--- /dev/null
+{
+ "git": {
+ "sha1": "d61d12e808c8691eb0a672d3f9b65560be970a44"
+ }
+}
--- /dev/null
+name: CI
+
+on:
+ pull_request:
+ push:
+ branches:
+ - staging
+ - trying
+
+jobs:
+ msrv:
+ name: Rust MSRV
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/checkout@v2
+ - uses: dtolnay/rust-toolchain@1.36.0
+ - run: cargo check --no-default-features
+ - run: cargo check --no-default-features --features "use_alloc"
+ - run: cargo check
+
+ stable:
+ name: Rust Stable
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/checkout@v2
+ - uses: dtolnay/rust-toolchain@stable
+ - run: cargo check --no-default-features
+ - run: cargo check --no-default-features --features "use_alloc"
+ - run: cargo test
+
+ # https://github.com/rust-lang/crater/blob/9ab6f9697c901c4a44025cf0a39b73ad5b37d198/.github/workflows/bors.yml#L125-L149
+ end-success:
+ name: bors build finished
+ if: success()
+ runs-on: ubuntu-latest
+ needs: [msrv,stable]
+
+ steps:
+ - name: Mark the job as successful
+ run: exit 0
--- /dev/null
+/target
+Cargo.lock
--- /dev/null
+# Temporarily disable rustfmt completely to avoid conflicts of newly formatted
+# code with old PRs.
+ignore = ["/"]
--- /dev/null
+# Changelog
+
+## 0.10.4
+ - Add `EitherOrBoth::or` and `EitherOrBoth::or_else` (#593)
+ - Add `min_set`, `max_set` et al. (#613, #323)
+ - Use `either/use_std` (#628)
+ - Documentation fixes (#612, #625, #632, #633, #634, #638)
+ - Code maintenance (#623, #624, #627, #630)
+
+## 0.10.2
+ - Add `Itertools::multiunzip` (#362, #565)
+ - Add `intersperse` and `intersperse_with` free functions (#555)
+ - Add `Itertools::sorted_by_cached_key` (#424, #575)
+ - Specialize `ProcessResults::fold` (#563)
+ - Fix subtraction overflow in `DuplicatesBy::size_hint` (#552)
+ - Fix specialization tests (#574)
+ - More `Debug` impls (#573)
+ - Deprecate `fold1` (use `reduce` instead) (#580)
+ - Documentation fixes (`HomogenousTuple`, `into_group_map`, `into_group_map_by`, `MultiPeek::peek`) (#543 et al.)
+
+## 0.10.1
+ - Add `Itertools::contains` (#514)
+ - Add `Itertools::counts_by` (#515)
+ - Add `Itertools::partition_result` (#511)
+ - Add `Itertools::all_unique` (#241)
+ - Add `Itertools::duplicates` and `Itertools::duplicates_by` (#502)
+ - Add `chain!` (#525)
+ - Add `Itertools::at_most_one` (#523)
+ - Add `Itertools::flatten_ok` (#527)
+ - Add `EitherOrBoth::or_default` (#583)
+ - Add `Itertools::find_or_last` and `Itertools::find_or_first` (#535)
+ - Implement `FusedIterator` for `FilterOk`, `FilterMapOk`, `InterleaveShortest`, `KMergeBy`, `MergeBy`, `PadUsing`, `Positions`, `Product` , `RcIter`, `TupleWindows`, `Unique`, `UniqueBy`, `Update`, `WhileSome`, `Combinations`, `CombinationsWithReplacement`, `Powerset`, `RepeatN`, and `WithPosition` (#550)
+ - Implement `FusedIterator` for `Interleave`, `IntersperseWith`, and `ZipLongest` (#548)
+
+## 0.10.0
+ - **Increase minimum supported Rust version to 1.32.0**
+ - Improve macro hygiene (#507)
+ - Add `Itertools::powerset` (#335)
+ - Add `Itertools::sorted_unstable`, `Itertools::sorted_unstable_by`, and `Itertools::sorted_unstable_by_key` (#494)
+ - Implement `Error` for `ExactlyOneError` (#484)
+ - Undeprecate `Itertools::fold_while` (#476)
+ - Tuple-related adapters work for tuples of arity up to 12 (#475)
+ - `use_alloc` feature for users who have `alloc`, but not `std` (#474)
+ - Add `Itertools::k_smallest` (#473)
+ - Add `Itertools::into_grouping_map` and `GroupingMap` (#465)
+ - Add `Itertools::into_grouping_map_by` and `GroupingMapBy` (#465)
+ - Add `Itertools::counts` (#468)
+ - Add implementation of `DoubleEndedIterator` for `Unique` (#442)
+ - Add implementation of `DoubleEndedIterator` for `UniqueBy` (#442)
+ - Add implementation of `DoubleEndedIterator` for `Zip` (#346)
+ - Add `Itertools::multipeek` (#435)
+ - Add `Itertools::dedup_with_count` and `DedupWithCount` (#423)
+ - Add `Itertools::dedup_by_with_count` and `DedupByWithCount` (#423)
+ - Add `Itertools::intersperse_with` and `IntersperseWith` (#381)
+ - Add `Itertools::filter_ok` and `FilterOk` (#377)
+ - Add `Itertools::filter_map_ok` and `FilterMapOk` (#377)
+ - Deprecate `Itertools::fold_results`, use `Itertools::fold_ok` instead (#377)
+ - Deprecate `Itertools::map_results`, use `Itertools::map_ok` instead (#377)
+ - Deprecate `FoldResults`, use `FoldOk` instead (#377)
+ - Deprecate `MapResults`, use `MapOk` instead (#377)
+ - Add `Itertools::circular_tuple_windows` and `CircularTupleWindows` (#350)
+ - Add `peek_nth` and `PeekNth` (#303)
+
+## 0.9.0
+ - Fix potential overflow in `MergeJoinBy::size_hint` (#385)
+ - Add `derive(Clone)` where possible (#382)
+ - Add `try_collect` method (#394)
+ - Add `HomogeneousTuple` trait (#389)
+ - Fix `combinations(0)` and `combinations_with_replacement(0)` (#383)
+ - Don't require `ParitalEq` to the `Item` of `DedupBy` (#397)
+ - Implement missing specializations on the `PutBack` adaptor and on the `MergeJoinBy` iterator (#372)
+ - Add `position_*` methods (#412)
+ - Derive `Hash` for `EitherOrBoth` (#417)
+ - Increase minimum supported Rust version to 1.32.0
+
+## 0.8.2
+ - Use `slice::iter` instead of `into_iter` to avoid future breakage (#378, by @LukasKalbertodt)
+## 0.8.1
+ - Added a [`.exactly_one()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.exactly_one) iterator method that, on success, extracts the single value of an iterator ; by @Xaeroxe
+ - Added combinatory iterator adaptors:
+ - [`.permutations(k)`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.permutations):
+
+ `[0, 1, 2].iter().permutations(2)` yields
+
+ ```rust
+ [
+ vec![0, 1],
+ vec![0, 2],
+ vec![1, 0],
+ vec![1, 2],
+ vec![2, 0],
+ vec![2, 1],
+ ]
+ ```
+
+ ; by @tobz1000
+
+ - [`.combinations_with_replacement(k)`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.combinations_with_replacement):
+
+ `[0, 1, 2].iter().combinations_with_replacement(2)` yields
+
+ ```rust
+ [
+ vec![0, 0],
+ vec![0, 1],
+ vec![0, 2],
+ vec![1, 1],
+ vec![1, 2],
+ vec![2, 2],
+ ]
+ ```
+
+ ; by @tommilligan
+
+ - For reference, these methods join the already existing [`.combinations(k)`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.combinations):
+
+ `[0, 1, 2].iter().combinations(2)` yields
+
+ ```rust
+ [
+ vec![0, 1],
+ vec![0, 2],
+ vec![1, 2],
+ ]
+ ```
+
+ - Improved the performance of [`.fold()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.fold)-based internal iteration for the [`.intersperse()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.intersperse) iterator ; by @jswrenn
+ - Added [`.dedup_by()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.dedup_by), [`.merge_by()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.merge_by) and [`.kmerge_by()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.kmerge_by) adaptors that work like [`.dedup()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.dedup), [`.merge()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.merge) and [`.kmerge()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.kmerge), but taking an additional custom comparison closure parameter. ; by @phimuemue
+ - Improved the performance of [`.all_equal()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.all_equal) ; by @fyrchik
+ - Loosened the bounds on [`.partition_map()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.partition_map) to take just a `FnMut` closure rather than a `Fn` closure, and made its implementation use internal iteration for better performance ; by @danielhenrymantilla
+ - Added convenience methods to [`EitherOrBoth`](https://docs.rs/itertools/0.8.1/itertools/enum.EitherOrBoth.html) elements yielded from the [`.zip_longest()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.zip_longest) iterator adaptor ; by @Avi-D-coder
+ - Added [`.sum1()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.sum1) and [`.product1()`](https://docs.rs/itertools/0.8.1/itertools/trait.Itertools.html#method.product1) iterator methods that respectively try to return the sum and the product of the elements of an iterator **when it is not empty**, otherwise they return `None` ; by @Emerentius
+## 0.8.0
+ - Added new adaptor `.map_into()` for conversions using `Into` by @vorner
+ - Improved `Itertools` docs by @JohnHeitmann
+ - The return type of `.sorted_by_by_key()` is now an iterator, not a Vec.
+ - The return type of the `izip!(x, y)` macro with exactly two arguments is now the usual `Iterator::zip`.
+ - Remove `.flatten()` in favour of std's `.flatten()`
+ - Deprecate `.foreach()` in favour of std's `.for_each()`
+ - Deprecate `.step()` in favour of std's `.step_by()`
+ - Deprecate `repeat_call` in favour of std's `repeat_with`
+ - Deprecate `.fold_while()` in favour of std's `.try_fold()`
+ - Require Rust 1.24 as minimal version.
+## 0.7.11
+ - Add convenience methods to `EitherOrBoth`, making it more similar to `Option` and `Either` by @jethrogb
+## 0.7.10
+ - No changes.
+## 0.7.9
+ - New inclusion policy: See the readme about suggesting features for std before accepting them in itertools.
+ - The `FoldWhile` type now implements `Eq` and `PartialEq` by @jturner314
+## 0.7.8
+ - Add new iterator method `.tree_fold1()` which is like `.fold1()` except items are combined in a tree structure (see its docs). By @scottmcm
+ - Add more `Debug` impls by @phimuemue: KMerge, KMergeBy, MergeJoinBy, ConsTuples, Intersperse, ProcessResults, RcIter, Tee, TupleWindows, Tee, ZipLongest, ZipEq, Zip.
+## 0.7.7
+ - Add new iterator method `.into_group_map() -> HashMap<K, Vec<V>>` which turns an iterator of `(K, V)` elements into such a hash table, where values are grouped by key. By @tobz1000
+ - Add new free function `flatten` for the `.flatten()` adaptor. **NOTE:** recent Rust nightlies have `Iterator::flatten` and thus a clash with our flatten adaptor. One workaround is to use the itertools `flatten` free function.
+## 0.7.6
+ - Add new adaptor `.multi_cartesian_product()` which is an n-ary product iterator by @tobz1000
+ - Add new method `.sorted_by_key()` by @Xion
+ - Provide simpler and faster `.count()` for `.unique()` and `.unique_by()`
+## 0.7.5
+ - `.multipeek()` now implements `PeekingNext`, by @nicopap.
+## 0.7.4
+ - Add new adaptor `.update()` by @lucasem; this adaptor is used to modify an element before passing it on in an iterator chain.
+## 0.7.3
+ - Add new method `.collect_tuple()` by @matklad; it makes a tuple out of the iterator's elements if the number of them matches **exactly**.
+ - Implement `fold` and `collect` for `.map_results()` which means it reuses the code of the standard `.map()` for these methods.
+## 0.7.2
+ - Add new adaptor `.merge_join_by` by @srijs; a heterogeneous merge join for two ordered sequences.
+## 0.7.1
+ - Iterator adaptors and iterators in itertools now use the same `must_use` reminder that the standard library adaptors do, by @matematikaedit and @bluss *“iterator adaptors are lazy and do nothing unless consumed”*.
+## 0.7.0
+ - Faster `izip!()` by @krdln
+ - `izip!()` is now a wrapper for repeated regular `.zip()` and a single `.map()`. This means it optimizes as well as the standard library `.zip()` it uses. **Note:** `multizip` and `izip!()` are now different! The former has a named type but the latter optimizes better.
+ - Faster `.unique()`
+ - `no_std` support, which is opt-in!
+ - Many lovable features are still there without std, like `izip!()` or `.format()` or `.merge()`, but not those that use collections.
+ - Trait bounds were required up front instead of just on the type: `group_by`'s `PartialEq` by @Phlosioneer and `repeat_call`'s `FnMut`.
+ - Removed deprecated constructor `Zip::new` — use `izip!()` or `multizip()`
+## 0.6.5
+ - Fix bug in `.cartesian_product()`'s fold (which only was visible for unfused iterators).
+## 0.6.4
+ - Add specific `fold` implementations for `.cartesian_product()` and `cons_tuples()`, which improves their performance in fold, foreach, and iterator consumers derived from them.
+## 0.6.3
+ - Add iterator adaptor `.positions(predicate)` by @tmccombs
+## 0.6.2
+ - Add function `process_results` which can “lift” a function of the regular values of an iterator so that it can process the `Ok` values from an iterator of `Results` instead, by @shepmaster
+ - Add iterator method `.concat()` which combines all iterator elements into a single collection using the `Extend` trait, by @srijs
+## 0.6.1
+ - Better size hint testing and subsequent size hint bugfixes by @rkarp. Fixes bugs in product, `interleave_shortest` size hints.
+ - New iterator method `.all_equal()` by @phimuemue
+## 0.6.0
+ - Deprecated names were removed in favour of their replacements
+ - `.flatten()` does not implement double ended iteration anymore
+ - `.fold_while()` uses `&mut self` and returns `FoldWhile<T>`, for composability #168
+ - `.foreach()` and `.fold1()` use `self`, like `.fold()` does.
+ - `.combinations(0)` now produces a single empty vector. #174
+## 0.5.10
+ - Add itertools method `.kmerge_by()` (and corresponding free function)
+ - Relaxed trait requirement of `.kmerge()` and `.minmax()` to PartialOrd.
+## 0.5.9
+ - Add multipeek method `.reset_peek()`
+ - Add categories
+## 0.5.8
+ - Add iterator adaptor `.peeking_take_while()` and its trait `PeekingNext`.
+## 0.5.7
+ - Add iterator adaptor `.with_position()`
+ - Fix multipeek's performance for long peeks by using `VecDeque`.
+## 0.5.6
+ - Add `.map_results()`
+## 0.5.5
+ - Many more adaptors now implement `Debug`
+ - Add free function constructor `repeat_n`. `RepeatN::new` is now deprecated.
+## 0.5.4
+ - Add infinite generator function `iterate`, that takes a seed and a closure.
+## 0.5.3
+ - Special-cased `.fold()` for flatten and put back. `.foreach()` now uses fold on the iterator, to pick up any iterator specific loop implementation.
+ - `.combinations(n)` asserts up front that `n != 0`, instead of running into an error on the second iterator element.
+## 0.5.2
+ - Add `.tuples::<T>()` that iterates by two, three or four elements at a time (where `T` is a tuple type).
+ - Add `.tuple_windows::<T>()` that iterates using a window of the two, three or four most recent elements.
+ - Add `.next_tuple::<T>()` method, that picks the next two, three or four elements in one go.
+ - `.interleave()` now has an accurate size hint.
+## 0.5.1
+ - Workaround module/function name clash that made racer crash on completing itertools. Only internal changes needed.
+## 0.5.0
+ - [Release announcement](https://bluss.github.io/rust/2016/09/26/itertools-0.5.0/)
+ - Renamed:
+ - `combinations` is now `tuple_combinations`
+ - `combinations_n` to `combinations`
+ - `group_by_lazy`, `chunks_lazy` to `group_by`, `chunks`
+ - `Unfold::new` to `unfold()`
+ - `RepeatCall::new` to `repeat_call()`
+ - `Zip::new` to `multizip`
+ - `PutBack::new`, `PutBackN::new` to `put_back`, `put_back_n`
+ - `PutBack::with_value` is now a builder setter, not a constructor
+ - `MultiPeek::new`, `.multipeek()` to `multipeek()`
+ - `format` to `format_with` and `format_default` to `format`
+ - `.into_rc()` to `rciter`
+ - `Partition` enum is now `Either`
+ - Module reorganization:
+ - All iterator structs are under `itertools::structs` but also reexported to the top level, for backwards compatibility
+ - All free functions are reexported at the root, `itertools::free` will be removed in the next version
+ - Removed:
+ - `ZipSlices`, use `.zip()` instead
+ - `.enumerate_from()`, `ZipTrusted`, due to being unstable
+ - `.mend_slices()`, moved to crate `odds`
+ - Stride, StrideMut, moved to crate `odds`
+ - `linspace()`, moved to crate `itertools-num`
+ - `.sort_by()`, use `.sorted_by()`
+ - `.is_empty_hint()`, use `.size_hint()`
+ - `.dropn()`, use `.dropping()`
+ - `.map_fn()`, use `.map()`
+ - `.slice()`, use `.take()` / `.skip()`
+ - helper traits in `misc`
+ - `new` constructors on iterator structs, use `Itertools` trait or free functions instead
+ - `itertools::size_hint` is now private
+ - Behaviour changes:
+ - `format` and `format_with` helpers now panic if you try to format them more than once.
+ - `repeat_call` is not double ended anymore
+ - New features:
+ - tuple flattening iterator is constructible with `cons_tuples`
+ - itertools reexports `Either` from the `either` crate. `Either<L, R>` is an iterator when `L, R` are.
+ - `MinMaxResult` now implements `Copy` and `Clone`
+ - `tuple_combinations` supports 1-4 tuples of combinations (previously just 2)
+## 0.4.19
+ - Add `.minmax_by()`
+ - Add `itertools::free::cloned`
+ - Add `itertools::free::rciter`
+ - Improve `.step(n)` slightly to take advantage of specialized Fuse better.
+## 0.4.18
+ - Only changes related to the "unstable" crate feature. This feature is more or less deprecated.
+ - Use deprecated warnings when unstable is enabled. `.enumerate_from()` will be removed imminently since it's using a deprecated libstd trait.
+## 0.4.17
+ - Fix bug in `.kmerge()` that caused it to often produce the wrong order #134
+## 0.4.16
+ - Improve precision of the `interleave_shortest` adaptor's size hint (it is now computed exactly when possible).
+## 0.4.15
+ - Fixup on top of the workaround in 0.4.14. A function in `itertools::free` was removed by mistake and now it is added back again.
+## 0.4.14
+ - Workaround an upstream regression in a Rust nightly build that broke compilation of of `itertools::free::{interleave, merge}`
+## 0.4.13
+ - Add `.minmax()` and `.minmax_by_key()`, iterator methods for finding both minimum and maximum in one scan.
+ - Add `.format_default()`, a simpler version of `.format()` (lazy formatting for iterators).
+## 0.4.12
+ - Add `.zip_eq()`, an adaptor like `.zip()` except it ensures iterators of inequal length don't pass silently (instead it panics).
+ - Add `.fold_while()`, an iterator method that is a fold that can short-circuit.
+ - Add `.partition_map()`, an iterator method that can separate elements into two collections.
+## 0.4.11
+ - Add `.get()` for `Stride{,Mut}` and `.get_mut()` for `StrideMut`
+## 0.4.10
+ - Improve performance of `.kmerge()`
+## 0.4.9
+ - Add k-ary merge adaptor `.kmerge()`
+ - Fix a bug in `.islice()` with ranges `a..b` where a `> b`.
+## 0.4.8
+ - Implement `Clone`, `Debug` for `Linspace`
+## 0.4.7
+ - Add function `diff_with()` that compares two iterators
+ - Add `.combinations_n()`, an n-ary combinations iterator
+ - Add methods `PutBack::with_value` and `PutBack::into_parts`.
+## 0.4.6
+ - Add method `.sorted()`
+ - Add module `itertools::free` with free function variants of common iterator adaptors and methods. For example `enumerate(iterable)`, `rev(iterable)`, and so on.
+## 0.4.5
+ - Add `.flatten()`
+## 0.4.4
+ - Allow composing `ZipSlices` with itself
+## 0.4.3
+ - Write `iproduct!()` as a single expression; this allows temporary values in its arguments.
+## 0.4.2
+ - Add `.fold_options()`
+ - Require Rust 1.1 or later
+## 0.4.1
+ - Update `.dropping()` to take advantage of `.nth()`
+## 0.4.0
+ - `.merge()`, `.unique()` and `.dedup()` now perform better due to not using function pointers
+ - Add free functions `enumerate()` and `rev()`
+ - Breaking changes:
+ - Return types of `.merge()` and `.merge_by()` renamed and changed
+ - Method `Merge::new` removed
+ - `.merge_by()` now takes a closure that returns bool.
+ - Return type of `.dedup()` changed
+ - Return type of `.mend_slices()` changed
+ - Return type of `.unique()` changed
+ - Removed function `times()`, struct `Times`: use a range instead
+ - Removed deprecated macro `icompr!()`
+ - Removed deprecated `FnMap` and method `.fn_map()`: use `.map_fn()`
+ - `.interleave_shortest()` is no longer guaranteed to act like fused
+## 0.3.25
+ - Rename `.sort_by()` to `.sorted_by()`. Old name is deprecated.
+ - Fix well-formedness warnings from RFC 1214, no user visible impact
+## 0.3.24
+ - Improve performance of `.merge()`'s ordering function slightly
+## 0.3.23
+ - Added `.chunks()`, similar to (and based on) `.group_by_lazy()`.
+ - Tweak linspace to match numpy.linspace and make it double ended.
+## 0.3.22
+ - Added `ZipSlices`, a fast zip for slices
+## 0.3.21
+ - Remove `Debug` impl for `Format`, it will have different use later
+## 0.3.20
+ - Optimize `.group_by_lazy()`
+## 0.3.19
+ - Added `.group_by_lazy()`, a possibly nonallocating group by
+ - Added `.format()`, a nonallocating formatting helper for iterators
+ - Remove uses of `RandomAccessIterator` since it has been deprecated in Rust.
+## 0.3.17
+ - Added (adopted) `Unfold` from Rust
+## 0.3.16
+ - Added adaptors `.unique()`, `.unique_by()`
+## 0.3.15
+ - Added method `.sort_by()`
+## 0.3.14
+ - Added adaptor `.while_some()`
+## 0.3.13
+ - Added adaptor `.interleave_shortest()`
+ - Added adaptor `.pad_using()`
+## 0.3.11
+ - Added `assert_equal` function
+## 0.3.10
+ - Bugfix `.combinations()` `size_hint`.
+## 0.3.8
+ - Added source `RepeatCall`
+## 0.3.7
+ - Added adaptor `PutBackN`
+ - Added adaptor `.combinations()`
+## 0.3.6
+ - Added `itertools::partition`, partition a sequence in place based on a predicate.
+ - Deprecate `icompr!()` with no replacement.
+## 0.3.5
+ - `.map_fn()` replaces deprecated `.fn_map()`.
+## 0.3.4
+ - `.take_while_ref()` *by-ref adaptor*
+ - `.coalesce()` *adaptor*
+ - `.mend_slices()` *adaptor*
+## 0.3.3
+ - `.dropping_back()` *method*
+ - `.fold1()` *method*
+ - `.is_empty_hint()` *method*
--- /dev/null
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+edition = "2018"
+name = "itertools"
+version = "0.10.5"
+authors = ["bluss"]
+exclude = ["/bors.toml"]
+description = "Extra iterator adaptors, iterator methods, free functions, and macros."
+documentation = "https://docs.rs/itertools/"
+readme = "README.md"
+keywords = ["iterator", "data-structure", "zip", "product", "group-by"]
+categories = ["algorithms", "rust-patterns"]
+license = "MIT/Apache-2.0"
+repository = "https://github.com/rust-itertools/itertools"
+[package.metadata.release]
+no-dev-version = true
+[profile.bench]
+debug = true
+
+[lib]
+test = false
+bench = false
+
+[[bench]]
+name = "tuple_combinations"
+harness = false
+
+[[bench]]
+name = "tuples"
+harness = false
+
+[[bench]]
+name = "fold_specialization"
+harness = false
+
+[[bench]]
+name = "combinations_with_replacement"
+harness = false
+
+[[bench]]
+name = "tree_fold1"
+harness = false
+
+[[bench]]
+name = "bench1"
+harness = false
+
+[[bench]]
+name = "combinations"
+harness = false
+
+[[bench]]
+name = "powerset"
+harness = false
+[dependencies.either]
+version = "1.0"
+default-features = false
+[dev-dependencies.criterion]
+version = "=0"
+
+[dev-dependencies.paste]
+version = "1.0.0"
+
+[dev-dependencies.permutohedron]
+version = "0.2"
+
+[dev-dependencies.quickcheck]
+version = "0.9"
+default-features = false
+
+[dev-dependencies.rand]
+version = "0.7"
+
+[features]
+default = ["use_std"]
+use_alloc = []
+use_std = ["use_alloc", "either/use_std"]
--- /dev/null
+[package]
+name = "itertools"
+version = "0.10.5"
+
+license = "MIT/Apache-2.0"
+repository = "https://github.com/rust-itertools/itertools"
+documentation = "https://docs.rs/itertools/"
+authors = ["bluss"]
+readme = "README.md"
+
+description = "Extra iterator adaptors, iterator methods, free functions, and macros."
+
+keywords = ["iterator", "data-structure", "zip", "product", "group-by"]
+categories = ["algorithms", "rust-patterns"]
+exclude = ["/bors.toml"]
+
+edition = "2018"
+
+[package.metadata.release]
+no-dev-version = true
+
+[lib]
+bench = false
+test = false
+
+[dependencies]
+either = { version = "1.0", default-features = false }
+
+[dev-dependencies]
+rand = "0.7"
+criterion = "=0" # TODO how could this work with our minimum supported Rust version?
+paste = "1.0.0" # Used in test_std to instantiate generic tests
+
+[dev-dependencies.quickcheck]
+version = "0.9"
+default-features = false
+
+[dev-dependencies.permutohedron]
+version = "0.2"
+
+[features]
+default = ["use_std"]
+use_std = ["use_alloc", "either/use_std"]
+use_alloc = []
+
+[profile]
+bench = { debug = true }
+
+[[bench]]
+name = "tuple_combinations"
+harness = false
+
+[[bench]]
+name = "tuples"
+harness = false
+
+[[bench]]
+name = "fold_specialization"
+harness = false
+
+[[bench]]
+name = "combinations_with_replacement"
+harness = false
+
+[[bench]]
+name = "tree_fold1"
+harness = false
+
+[[bench]]
+name = "bench1"
+harness = false
+
+[[bench]]
+name = "combinations"
+harness = false
+
+[[bench]]
+name = "powerset"
+harness = false
--- /dev/null
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
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+you may not use this file except in compliance with the License.
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+
+Unless required by applicable law or agreed to in writing, software
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+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
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--- /dev/null
+Copyright (c) 2015
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
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+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
--- /dev/null
+# Itertools
+
+Extra iterator adaptors, functions and macros.
+
+Please read the [API documentation here](https://docs.rs/itertools/).
+
+[](https://github.com/rust-itertools/itertools/actions)
+[](https://crates.io/crates/itertools)
+
+How to use with Cargo:
+
+```toml
+[dependencies]
+itertools = "0.10.5"
+```
+
+How to use in your crate:
+
+```rust
+use itertools::Itertools;
+```
+
+## How to contribute
+
+- Fix a bug or implement a new thing
+- Include tests for your new feature, preferably a QuickCheck test
+- Make a Pull Request
+
+For new features, please first consider filing a PR to [rust-lang/rust](https://github.com/rust-lang/rust),
+adding your new feature to the `Iterator` trait of the standard library, if you believe it is reasonable.
+If it isn't accepted there, proposing it for inclusion in ``itertools`` is a good idea.
+The reason for doing is this is so that we avoid future breakage as with ``.flatten()``.
+However, if your feature involves heap allocation, such as storing elements in a ``Vec<T>``,
+then it can't be accepted into ``libcore``, and you should propose it for ``itertools`` directly instead.
+
+## License
+
+Dual-licensed to be compatible with the Rust project.
+
+Licensed under the Apache License, Version 2.0
+https://www.apache.org/licenses/LICENSE-2.0 or the MIT license
+https://opensource.org/licenses/MIT, at your
+option. This file may not be copied, modified, or distributed
+except according to those terms.
--- /dev/null
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+use itertools::free::cloned;
+use itertools::iproduct;
+
+use std::iter::repeat;
+use std::cmp;
+use std::ops::{Add, Range};
+
+mod extra;
+
+use crate::extra::ZipSlices;
+
+fn slice_iter(c: &mut Criterion) {
+ let xs: Vec<_> = repeat(1i32).take(20).collect();
+
+ c.bench_function("slice iter", move |b| {
+ b.iter(|| for elt in xs.iter() {
+ black_box(elt);
+ })
+ });
+}
+
+fn slice_iter_rev(c: &mut Criterion) {
+ let xs: Vec<_> = repeat(1i32).take(20).collect();
+
+ c.bench_function("slice iter rev", move |b| {
+ b.iter(|| for elt in xs.iter().rev() {
+ black_box(elt);
+ })
+ });
+}
+
+fn zip_default_zip(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zip default zip", move |b| {
+ b.iter(|| {
+ for (&x, &y) in xs.iter().zip(&ys) {
+ black_box(x);
+ black_box(y);
+ }
+ })
+ });
+}
+
+fn zipdot_i32_default_zip(c: &mut Criterion) {
+ let xs = vec![2; 1024];
+ let ys = vec![2; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot i32 default zip", move |b| {
+ b.iter(|| {
+ let mut s = 0;
+ for (&x, &y) in xs.iter().zip(&ys) {
+ s += x * y;
+ }
+ s
+ })
+ });
+}
+
+fn zipdot_f32_default_zip(c: &mut Criterion) {
+ let xs = vec![2f32; 1024];
+ let ys = vec![2f32; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot f32 default zip", move |b| {
+ b.iter(|| {
+ let mut s = 0.;
+ for (&x, &y) in xs.iter().zip(&ys) {
+ s += x * y;
+ }
+ s
+ })
+ });
+}
+
+fn zip_default_zip3(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let zs = vec![0; 766];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+ let zs = black_box(zs);
+
+ c.bench_function("zip default zip3", move |b| {
+ b.iter(|| {
+ for ((&x, &y), &z) in xs.iter().zip(&ys).zip(&zs) {
+ black_box(x);
+ black_box(y);
+ black_box(z);
+ }
+ })
+ });
+}
+
+fn zip_slices_ziptuple(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+
+ c.bench_function("zip slices ziptuple", move |b| {
+ b.iter(|| {
+ let xs = black_box(&xs);
+ let ys = black_box(&ys);
+ for (&x, &y) in itertools::multizip((xs, ys)) {
+ black_box(x);
+ black_box(y);
+ }
+ })
+ });
+}
+
+fn zipslices(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipslices", move |b| {
+ b.iter(|| {
+ for (&x, &y) in ZipSlices::new(&xs, &ys) {
+ black_box(x);
+ black_box(y);
+ }
+ })
+ });
+}
+
+fn zipslices_mut(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let xs = black_box(xs);
+ let mut ys = black_box(ys);
+
+ c.bench_function("zipslices mut", move |b| {
+ b.iter(|| {
+ for (&x, &mut y) in ZipSlices::from_slices(&xs[..], &mut ys[..]) {
+ black_box(x);
+ black_box(y);
+ }
+ })
+ });
+}
+
+fn zipdot_i32_zipslices(c: &mut Criterion) {
+ let xs = vec![2; 1024];
+ let ys = vec![2; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot i32 zipslices", move |b| {
+ b.iter(|| {
+ let mut s = 0i32;
+ for (&x, &y) in ZipSlices::new(&xs, &ys) {
+ s += x * y;
+ }
+ s
+ })
+ });
+}
+
+fn zipdot_f32_zipslices(c: &mut Criterion) {
+ let xs = vec![2f32; 1024];
+ let ys = vec![2f32; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot f32 zipslices", move |b| {
+ b.iter(|| {
+ let mut s = 0.;
+ for (&x, &y) in ZipSlices::new(&xs, &ys) {
+ s += x * y;
+ }
+ s
+ })
+ });
+}
+
+fn zip_checked_counted_loop(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zip checked counted loop", move |b| {
+ b.iter(|| {
+ // Must slice to equal lengths, and then bounds checks are eliminated!
+ let len = cmp::min(xs.len(), ys.len());
+ let xs = &xs[..len];
+ let ys = &ys[..len];
+
+ for i in 0..len {
+ let x = xs[i];
+ let y = ys[i];
+ black_box(x);
+ black_box(y);
+ }
+ })
+ });
+}
+
+fn zipdot_i32_checked_counted_loop(c: &mut Criterion) {
+ let xs = vec![2; 1024];
+ let ys = vec![2; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot i32 checked counted loop", move |b| {
+ b.iter(|| {
+ // Must slice to equal lengths, and then bounds checks are eliminated!
+ let len = cmp::min(xs.len(), ys.len());
+ let xs = &xs[..len];
+ let ys = &ys[..len];
+
+ let mut s = 0i32;
+
+ for i in 0..len {
+ s += xs[i] * ys[i];
+ }
+ s
+ })
+ });
+}
+
+fn zipdot_f32_checked_counted_loop(c: &mut Criterion) {
+ let xs = vec![2f32; 1024];
+ let ys = vec![2f32; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot f32 checked counted loop", move |b| {
+ b.iter(|| {
+ // Must slice to equal lengths, and then bounds checks are eliminated!
+ let len = cmp::min(xs.len(), ys.len());
+ let xs = &xs[..len];
+ let ys = &ys[..len];
+
+ let mut s = 0.;
+
+ for i in 0..len {
+ s += xs[i] * ys[i];
+ }
+ s
+ })
+ });
+}
+
+fn zipdot_f32_checked_counted_unrolled_loop(c: &mut Criterion) {
+ let xs = vec![2f32; 1024];
+ let ys = vec![2f32; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot f32 checked counted unrolled loop", move |b| {
+ b.iter(|| {
+ // Must slice to equal lengths, and then bounds checks are eliminated!
+ let len = cmp::min(xs.len(), ys.len());
+ let mut xs = &xs[..len];
+ let mut ys = &ys[..len];
+
+ let mut s = 0.;
+ let (mut p0, mut p1, mut p2, mut p3, mut p4, mut p5, mut p6, mut p7) =
+ (0., 0., 0., 0., 0., 0., 0., 0.);
+
+ // how to unroll and have bounds checks eliminated (by cristicbz)
+ // split sum into eight parts to enable vectorization (by bluss)
+ while xs.len() >= 8 {
+ p0 += xs[0] * ys[0];
+ p1 += xs[1] * ys[1];
+ p2 += xs[2] * ys[2];
+ p3 += xs[3] * ys[3];
+ p4 += xs[4] * ys[4];
+ p5 += xs[5] * ys[5];
+ p6 += xs[6] * ys[6];
+ p7 += xs[7] * ys[7];
+
+ xs = &xs[8..];
+ ys = &ys[8..];
+ }
+ s += p0 + p4;
+ s += p1 + p5;
+ s += p2 + p6;
+ s += p3 + p7;
+
+ for i in 0..xs.len() {
+ s += xs[i] * ys[i];
+ }
+ s
+ })
+ });
+}
+
+fn zip_unchecked_counted_loop(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zip unchecked counted loop", move |b| {
+ b.iter(|| {
+ let len = cmp::min(xs.len(), ys.len());
+ for i in 0..len {
+ unsafe {
+ let x = *xs.get_unchecked(i);
+ let y = *ys.get_unchecked(i);
+ black_box(x);
+ black_box(y);
+ }
+ }
+ })
+ });
+}
+
+fn zipdot_i32_unchecked_counted_loop(c: &mut Criterion) {
+ let xs = vec![2; 1024];
+ let ys = vec![2; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot i32 unchecked counted loop", move |b| {
+ b.iter(|| {
+ let len = cmp::min(xs.len(), ys.len());
+ let mut s = 0i32;
+ for i in 0..len {
+ unsafe {
+ let x = *xs.get_unchecked(i);
+ let y = *ys.get_unchecked(i);
+ s += x * y;
+ }
+ }
+ s
+ })
+ });
+}
+
+fn zipdot_f32_unchecked_counted_loop(c: &mut Criterion) {
+ let xs = vec![2.; 1024];
+ let ys = vec![2.; 768];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+
+ c.bench_function("zipdot f32 unchecked counted loop", move |b| {
+ b.iter(|| {
+ let len = cmp::min(xs.len(), ys.len());
+ let mut s = 0f32;
+ for i in 0..len {
+ unsafe {
+ let x = *xs.get_unchecked(i);
+ let y = *ys.get_unchecked(i);
+ s += x * y;
+ }
+ }
+ s
+ })
+ });
+}
+
+fn zip_unchecked_counted_loop3(c: &mut Criterion) {
+ let xs = vec![0; 1024];
+ let ys = vec![0; 768];
+ let zs = vec![0; 766];
+ let xs = black_box(xs);
+ let ys = black_box(ys);
+ let zs = black_box(zs);
+
+ c.bench_function("zip unchecked counted loop3", move |b| {
+ b.iter(|| {
+ let len = cmp::min(xs.len(), cmp::min(ys.len(), zs.len()));
+ for i in 0..len {
+ unsafe {
+ let x = *xs.get_unchecked(i);
+ let y = *ys.get_unchecked(i);
+ let z = *zs.get_unchecked(i);
+ black_box(x);
+ black_box(y);
+ black_box(z);
+ }
+ }
+ })
+ });
+}
+
+fn group_by_lazy_1(c: &mut Criterion) {
+ let mut data = vec![0; 1024];
+ for (index, elt) in data.iter_mut().enumerate() {
+ *elt = index / 10;
+ }
+
+ let data = black_box(data);
+
+ c.bench_function("group by lazy 1", move |b| {
+ b.iter(|| {
+ for (_key, group) in &data.iter().group_by(|elt| **elt) {
+ for elt in group {
+ black_box(elt);
+ }
+ }
+ })
+ });
+}
+
+fn group_by_lazy_2(c: &mut Criterion) {
+ let mut data = vec![0; 1024];
+ for (index, elt) in data.iter_mut().enumerate() {
+ *elt = index / 2;
+ }
+
+ let data = black_box(data);
+
+ c.bench_function("group by lazy 2", move |b| {
+ b.iter(|| {
+ for (_key, group) in &data.iter().group_by(|elt| **elt) {
+ for elt in group {
+ black_box(elt);
+ }
+ }
+ })
+ });
+}
+
+fn slice_chunks(c: &mut Criterion) {
+ let data = vec![0; 1024];
+
+ let data = black_box(data);
+ let sz = black_box(10);
+
+ c.bench_function("slice chunks", move |b| {
+ b.iter(|| {
+ for group in data.chunks(sz) {
+ for elt in group {
+ black_box(elt);
+ }
+ }
+ })
+ });
+}
+
+fn chunks_lazy_1(c: &mut Criterion) {
+ let data = vec![0; 1024];
+
+ let data = black_box(data);
+ let sz = black_box(10);
+
+ c.bench_function("chunks lazy 1", move |b| {
+ b.iter(|| {
+ for group in &data.iter().chunks(sz) {
+ for elt in group {
+ black_box(elt);
+ }
+ }
+ })
+ });
+}
+
+fn equal(c: &mut Criterion) {
+ let data = vec![7; 1024];
+ let l = data.len();
+ let alpha = black_box(&data[1..]);
+ let beta = black_box(&data[..l - 1]);
+
+ c.bench_function("equal", move |b| {
+ b.iter(|| {
+ itertools::equal(alpha, beta)
+ })
+ });
+}
+
+fn merge_default(c: &mut Criterion) {
+ let mut data1 = vec![0; 1024];
+ let mut data2 = vec![0; 800];
+ let mut x = 0;
+ for (_, elt) in data1.iter_mut().enumerate() {
+ *elt = x;
+ x += 1;
+ }
+
+ let mut y = 0;
+ for (i, elt) in data2.iter_mut().enumerate() {
+ *elt += y;
+ if i % 3 == 0 {
+ y += 3;
+ } else {
+ y += 0;
+ }
+ }
+ let data1 = black_box(data1);
+ let data2 = black_box(data2);
+
+ c.bench_function("merge default", move |b| {
+ b.iter(|| {
+ data1.iter().merge(&data2).count()
+ })
+ });
+}
+
+fn merge_by_cmp(c: &mut Criterion) {
+ let mut data1 = vec![0; 1024];
+ let mut data2 = vec![0; 800];
+ let mut x = 0;
+ for (_, elt) in data1.iter_mut().enumerate() {
+ *elt = x;
+ x += 1;
+ }
+
+ let mut y = 0;
+ for (i, elt) in data2.iter_mut().enumerate() {
+ *elt += y;
+ if i % 3 == 0 {
+ y += 3;
+ } else {
+ y += 0;
+ }
+ }
+ let data1 = black_box(data1);
+ let data2 = black_box(data2);
+
+ c.bench_function("merge by cmp", move |b| {
+ b.iter(|| {
+ data1.iter().merge_by(&data2, PartialOrd::le).count()
+ })
+ });
+}
+
+fn merge_by_lt(c: &mut Criterion) {
+ let mut data1 = vec![0; 1024];
+ let mut data2 = vec![0; 800];
+ let mut x = 0;
+ for (_, elt) in data1.iter_mut().enumerate() {
+ *elt = x;
+ x += 1;
+ }
+
+ let mut y = 0;
+ for (i, elt) in data2.iter_mut().enumerate() {
+ *elt += y;
+ if i % 3 == 0 {
+ y += 3;
+ } else {
+ y += 0;
+ }
+ }
+ let data1 = black_box(data1);
+ let data2 = black_box(data2);
+
+ c.bench_function("merge by lt", move |b| {
+ b.iter(|| {
+ data1.iter().merge_by(&data2, |a, b| a <= b).count()
+ })
+ });
+}
+
+fn kmerge_default(c: &mut Criterion) {
+ let mut data1 = vec![0; 1024];
+ let mut data2 = vec![0; 800];
+ let mut x = 0;
+ for (_, elt) in data1.iter_mut().enumerate() {
+ *elt = x;
+ x += 1;
+ }
+
+ let mut y = 0;
+ for (i, elt) in data2.iter_mut().enumerate() {
+ *elt += y;
+ if i % 3 == 0 {
+ y += 3;
+ } else {
+ y += 0;
+ }
+ }
+ let data1 = black_box(data1);
+ let data2 = black_box(data2);
+ let its = &[data1.iter(), data2.iter()];
+
+ c.bench_function("kmerge default", move |b| {
+ b.iter(|| {
+ its.iter().cloned().kmerge().count()
+ })
+ });
+}
+
+fn kmerge_tenway(c: &mut Criterion) {
+ let mut data = vec![0; 10240];
+
+ let mut state = 1729u16;
+ fn rng(state: &mut u16) -> u16 {
+ let new = state.wrapping_mul(31421) + 6927;
+ *state = new;
+ new
+ }
+
+ for elt in &mut data {
+ *elt = rng(&mut state);
+ }
+
+ let mut chunks = Vec::new();
+ let mut rest = &mut data[..];
+ while rest.len() > 0 {
+ let chunk_len = 1 + rng(&mut state) % 512;
+ let chunk_len = cmp::min(rest.len(), chunk_len as usize);
+ let (fst, tail) = {rest}.split_at_mut(chunk_len);
+ fst.sort();
+ chunks.push(fst.iter().cloned());
+ rest = tail;
+ }
+
+ // println!("Chunk lengths: {}", chunks.iter().format_with(", ", |elt, f| f(&elt.len())));
+
+ c.bench_function("kmerge tenway", move |b| {
+ b.iter(|| {
+ chunks.iter().cloned().kmerge().count()
+ })
+ });
+}
+
+fn fast_integer_sum<I>(iter: I) -> I::Item
+ where I: IntoIterator,
+ I::Item: Default + Add<Output=I::Item>
+{
+ iter.into_iter().fold(<_>::default(), |x, y| x + y)
+}
+
+fn step_vec_2(c: &mut Criterion) {
+ let v = vec![0; 1024];
+
+ c.bench_function("step vec 2", move |b| {
+ b.iter(|| {
+ fast_integer_sum(cloned(v.iter().step_by(2)))
+ })
+ });
+}
+
+fn step_vec_10(c: &mut Criterion) {
+ let v = vec![0; 1024];
+
+ c.bench_function("step vec 10", move |b| {
+ b.iter(|| {
+ fast_integer_sum(cloned(v.iter().step_by(10)))
+ })
+ });
+}
+
+fn step_range_2(c: &mut Criterion) {
+ let v = black_box(0..1024);
+
+ c.bench_function("step range 2", move |b| {
+ b.iter(|| {
+ fast_integer_sum(v.clone().step_by(2))
+ })
+ });
+}
+
+fn step_range_10(c: &mut Criterion) {
+ let v = black_box(0..1024);
+
+ c.bench_function("step range 10", move |b| {
+ b.iter(|| {
+ fast_integer_sum(v.clone().step_by(10))
+ })
+ });
+}
+
+fn cartesian_product_iterator(c: &mut Criterion) {
+ let xs = vec![0; 16];
+
+ c.bench_function("cartesian product iterator", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ for (&x, &y, &z) in iproduct!(&xs, &xs, &xs) {
+ sum += x;
+ sum += y;
+ sum += z;
+ }
+ sum
+ })
+ });
+}
+
+fn cartesian_product_fold(c: &mut Criterion) {
+ let xs = vec![0; 16];
+
+ c.bench_function("cartesian product fold", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ iproduct!(&xs, &xs, &xs).fold((), |(), (&x, &y, &z)| {
+ sum += x;
+ sum += y;
+ sum += z;
+ });
+ sum
+ })
+ });
+}
+
+fn multi_cartesian_product_iterator(c: &mut Criterion) {
+ let xs = [vec![0; 16], vec![0; 16], vec![0; 16]];
+
+ c.bench_function("multi cartesian product iterator", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ for x in xs.iter().multi_cartesian_product() {
+ sum += x[0];
+ sum += x[1];
+ sum += x[2];
+ }
+ sum
+ })
+ });
+}
+
+fn multi_cartesian_product_fold(c: &mut Criterion) {
+ let xs = [vec![0; 16], vec![0; 16], vec![0; 16]];
+
+ c.bench_function("multi cartesian product fold", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ xs.iter().multi_cartesian_product().fold((), |(), x| {
+ sum += x[0];
+ sum += x[1];
+ sum += x[2];
+ });
+ sum
+ })
+ });
+}
+
+fn cartesian_product_nested_for(c: &mut Criterion) {
+ let xs = vec![0; 16];
+
+ c.bench_function("cartesian product nested for", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ for &x in &xs {
+ for &y in &xs {
+ for &z in &xs {
+ sum += x;
+ sum += y;
+ sum += z;
+ }
+ }
+ }
+ sum
+ })
+ });
+}
+
+fn all_equal(c: &mut Criterion) {
+ let mut xs = vec![0; 5_000_000];
+ xs.extend(vec![1; 5_000_000]);
+
+ c.bench_function("all equal", move |b| {
+ b.iter(|| xs.iter().all_equal())
+ });
+}
+
+fn all_equal_for(c: &mut Criterion) {
+ let mut xs = vec![0; 5_000_000];
+ xs.extend(vec![1; 5_000_000]);
+
+ c.bench_function("all equal for", move |b| {
+ b.iter(|| {
+ for &x in &xs {
+ if x != xs[0] {
+ return false;
+ }
+ }
+ true
+ })
+ });
+}
+
+fn all_equal_default(c: &mut Criterion) {
+ let mut xs = vec![0; 5_000_000];
+ xs.extend(vec![1; 5_000_000]);
+
+ c.bench_function("all equal default", move |b| {
+ b.iter(|| xs.iter().dedup().nth(1).is_none())
+ });
+}
+
+const PERM_COUNT: usize = 6;
+
+fn permutations_iter(c: &mut Criterion) {
+ struct NewIterator(Range<usize>);
+
+ impl Iterator for NewIterator {
+ type Item = usize;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.0.next()
+ }
+ }
+
+ c.bench_function("permutations iter", move |b| {
+ b.iter(|| {
+ for _ in NewIterator(0..PERM_COUNT).permutations(PERM_COUNT) {
+
+ }
+ })
+ });
+}
+
+fn permutations_range(c: &mut Criterion) {
+ c.bench_function("permutations range", move |b| {
+ b.iter(|| {
+ for _ in (0..PERM_COUNT).permutations(PERM_COUNT) {
+
+ }
+ })
+ });
+}
+
+fn permutations_slice(c: &mut Criterion) {
+ let v = (0..PERM_COUNT).collect_vec();
+
+ c.bench_function("permutations slice", move |b| {
+ b.iter(|| {
+ for _ in v.as_slice().iter().permutations(PERM_COUNT) {
+
+ }
+ })
+ });
+}
+
+criterion_group!(
+ benches,
+ slice_iter,
+ slice_iter_rev,
+ zip_default_zip,
+ zipdot_i32_default_zip,
+ zipdot_f32_default_zip,
+ zip_default_zip3,
+ zip_slices_ziptuple,
+ zipslices,
+ zipslices_mut,
+ zipdot_i32_zipslices,
+ zipdot_f32_zipslices,
+ zip_checked_counted_loop,
+ zipdot_i32_checked_counted_loop,
+ zipdot_f32_checked_counted_loop,
+ zipdot_f32_checked_counted_unrolled_loop,
+ zip_unchecked_counted_loop,
+ zipdot_i32_unchecked_counted_loop,
+ zipdot_f32_unchecked_counted_loop,
+ zip_unchecked_counted_loop3,
+ group_by_lazy_1,
+ group_by_lazy_2,
+ slice_chunks,
+ chunks_lazy_1,
+ equal,
+ merge_default,
+ merge_by_cmp,
+ merge_by_lt,
+ kmerge_default,
+ kmerge_tenway,
+ step_vec_2,
+ step_vec_10,
+ step_range_2,
+ step_range_10,
+ cartesian_product_iterator,
+ cartesian_product_fold,
+ multi_cartesian_product_iterator,
+ multi_cartesian_product_fold,
+ cartesian_product_nested_for,
+ all_equal,
+ all_equal_for,
+ all_equal_default,
+ permutations_iter,
+ permutations_range,
+ permutations_slice,
+);
+criterion_main!(benches);
--- /dev/null
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+// approximate 100_000 iterations for each combination
+const N1: usize = 100_000;
+const N2: usize = 448;
+const N3: usize = 86;
+const N4: usize = 41;
+const N14: usize = 21;
+
+fn comb_for1(c: &mut Criterion) {
+ c.bench_function("comb for1", move |b| {
+ b.iter(|| {
+ for i in 0..N1 {
+ black_box(vec![i]);
+ }
+ })
+ });
+}
+
+fn comb_for2(c: &mut Criterion) {
+ c.bench_function("comb for2", move |b| {
+ b.iter(|| {
+ for i in 0..N2 {
+ for j in (i + 1)..N2 {
+ black_box(vec![i, j]);
+ }
+ }
+ })
+ });
+}
+
+fn comb_for3(c: &mut Criterion) {
+ c.bench_function("comb for3", move |b| {
+ b.iter(|| {
+ for i in 0..N3 {
+ for j in (i + 1)..N3 {
+ for k in (j + 1)..N3 {
+ black_box(vec![i, j, k]);
+ }
+ }
+ }
+ })
+ });
+}
+
+fn comb_for4(c: &mut Criterion) {
+ c.bench_function("comb for4", move |b| {
+ b.iter(|| {
+ for i in 0..N4 {
+ for j in (i + 1)..N4 {
+ for k in (j + 1)..N4 {
+ for l in (k + 1)..N4 {
+ black_box(vec![i, j, k, l]);
+ }
+ }
+ }
+ }
+ })
+ });
+}
+
+fn comb_c1(c: &mut Criterion) {
+ c.bench_function("comb c1", move |b| {
+ b.iter(|| {
+ for combo in (0..N1).combinations(1) {
+ black_box(combo);
+ }
+ })
+ });
+}
+
+fn comb_c2(c: &mut Criterion) {
+ c.bench_function("comb c2", move |b| {
+ b.iter(|| {
+ for combo in (0..N2).combinations(2) {
+ black_box(combo);
+ }
+ })
+ });
+}
+
+fn comb_c3(c: &mut Criterion) {
+ c.bench_function("comb c3", move |b| {
+ b.iter(|| {
+ for combo in (0..N3).combinations(3) {
+ black_box(combo);
+ }
+ })
+ });
+}
+
+fn comb_c4(c: &mut Criterion) {
+ c.bench_function("comb c4", move |b| {
+ b.iter(|| {
+ for combo in (0..N4).combinations(4) {
+ black_box(combo);
+ }
+ })
+ });
+}
+
+fn comb_c14(c: &mut Criterion) {
+ c.bench_function("comb c14", move |b| {
+ b.iter(|| {
+ for combo in (0..N14).combinations(14) {
+ black_box(combo);
+ }
+ })
+ });
+}
+
+criterion_group!(
+ benches,
+ comb_for1,
+ comb_for2,
+ comb_for3,
+ comb_for4,
+ comb_c1,
+ comb_c2,
+ comb_c3,
+ comb_c4,
+ comb_c14,
+);
+criterion_main!(benches);
--- /dev/null
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+fn comb_replacement_n10_k5(c: &mut Criterion) {
+ c.bench_function("comb replacement n10k5", move |b| {
+ b.iter(|| {
+ for i in (0..10).combinations_with_replacement(5) {
+ black_box(i);
+ }
+ })
+ });
+}
+
+fn comb_replacement_n5_k10(c: &mut Criterion) {
+ c.bench_function("comb replacement n5 k10", move |b| {
+ b.iter(|| {
+ for i in (0..5).combinations_with_replacement(10) {
+ black_box(i);
+ }
+ })
+ });
+}
+
+fn comb_replacement_n10_k10(c: &mut Criterion) {
+ c.bench_function("comb replacement n10 k10", move |b| {
+ b.iter(|| {
+ for i in (0..10).combinations_with_replacement(10) {
+ black_box(i);
+ }
+ })
+ });
+}
+
+criterion_group!(
+ benches,
+ comb_replacement_n10_k5,
+ comb_replacement_n5_k10,
+ comb_replacement_n10_k10,
+);
+criterion_main!(benches);
--- /dev/null
+pub use self::zipslices::ZipSlices;
+mod zipslices;
--- /dev/null
+use std::cmp;
+
+// Note: There are different ways to implement ZipSlices.
+// This version performed the best in benchmarks.
+//
+// I also implemented a version with three pointers (tptr, tend, uptr),
+// that mimiced slice::Iter and only checked bounds by using tptr == tend,
+// but that was inferior to this solution.
+
+/// An iterator which iterates two slices simultaneously.
+///
+/// `ZipSlices` acts like a double-ended `.zip()` iterator.
+///
+/// It was intended to be more efficient than `.zip()`, and it was, then
+/// rustc changed how it optimizes so it can not promise improved performance
+/// at this time.
+///
+/// Note that elements past the end of the shortest of the two slices are ignored.
+///
+/// Iterator element type for `ZipSlices<T, U>` is `(T::Item, U::Item)`. For example,
+/// for a `ZipSlices<&'a [A], &'b mut [B]>`, the element type is `(&'a A, &'b mut B)`.
+#[derive(Clone)]
+pub struct ZipSlices<T, U> {
+ t: T,
+ u: U,
+ len: usize,
+ index: usize,
+}
+
+impl<'a, 'b, A, B> ZipSlices<&'a [A], &'b [B]> {
+ /// Create a new `ZipSlices` from slices `a` and `b`.
+ ///
+ /// Act like a double-ended `.zip()` iterator, but more efficiently.
+ ///
+ /// Note that elements past the end of the shortest of the two slices are ignored.
+ #[inline(always)]
+ pub fn new(a: &'a [A], b: &'b [B]) -> Self {
+ let minl = cmp::min(a.len(), b.len());
+ ZipSlices {
+ t: a,
+ u: b,
+ len: minl,
+ index: 0,
+ }
+ }
+}
+
+impl<T, U> ZipSlices<T, U>
+ where T: Slice,
+ U: Slice
+{
+ /// Create a new `ZipSlices` from slices `a` and `b`.
+ ///
+ /// Act like a double-ended `.zip()` iterator, but more efficiently.
+ ///
+ /// Note that elements past the end of the shortest of the two slices are ignored.
+ #[inline(always)]
+ pub fn from_slices(a: T, b: U) -> Self {
+ let minl = cmp::min(a.len(), b.len());
+ ZipSlices {
+ t: a,
+ u: b,
+ len: minl,
+ index: 0,
+ }
+ }
+}
+
+impl<T, U> Iterator for ZipSlices<T, U>
+ where T: Slice,
+ U: Slice
+{
+ type Item = (T::Item, U::Item);
+
+ #[inline(always)]
+ fn next(&mut self) -> Option<Self::Item> {
+ unsafe {
+ if self.index >= self.len {
+ None
+ } else {
+ let i = self.index;
+ self.index += 1;
+ Some((
+ self.t.get_unchecked(i),
+ self.u.get_unchecked(i)))
+ }
+ }
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let len = self.len - self.index;
+ (len, Some(len))
+ }
+}
+
+impl<T, U> DoubleEndedIterator for ZipSlices<T, U>
+ where T: Slice,
+ U: Slice
+{
+ #[inline(always)]
+ fn next_back(&mut self) -> Option<Self::Item> {
+ unsafe {
+ if self.index >= self.len {
+ None
+ } else {
+ self.len -= 1;
+ let i = self.len;
+ Some((
+ self.t.get_unchecked(i),
+ self.u.get_unchecked(i)))
+ }
+ }
+ }
+}
+
+impl<T, U> ExactSizeIterator for ZipSlices<T, U>
+ where T: Slice,
+ U: Slice
+{}
+
+unsafe impl<T, U> Slice for ZipSlices<T, U>
+ where T: Slice,
+ U: Slice
+{
+ type Item = (T::Item, U::Item);
+
+ fn len(&self) -> usize {
+ self.len - self.index
+ }
+
+ unsafe fn get_unchecked(&mut self, i: usize) -> Self::Item {
+ (self.t.get_unchecked(i),
+ self.u.get_unchecked(i))
+ }
+}
+
+/// A helper trait to let `ZipSlices` accept both `&[T]` and `&mut [T]`.
+///
+/// Unsafe trait because:
+///
+/// - Implementors must guarantee that `get_unchecked` is valid for all indices `0..len()`.
+pub unsafe trait Slice {
+ /// The type of a reference to the slice's elements
+ type Item;
+ #[doc(hidden)]
+ fn len(&self) -> usize;
+ #[doc(hidden)]
+ unsafe fn get_unchecked(&mut self, i: usize) -> Self::Item;
+}
+
+unsafe impl<'a, T> Slice for &'a [T] {
+ type Item = &'a T;
+ #[inline(always)]
+ fn len(&self) -> usize { (**self).len() }
+ #[inline(always)]
+ unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
+ debug_assert!(i < self.len());
+ (**self).get_unchecked(i)
+ }
+}
+
+unsafe impl<'a, T> Slice for &'a mut [T] {
+ type Item = &'a mut T;
+ #[inline(always)]
+ fn len(&self) -> usize { (**self).len() }
+ #[inline(always)]
+ unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
+ debug_assert!(i < self.len());
+ // override the lifetime constraints of &mut &'a mut [T]
+ (*(*self as *mut [T])).get_unchecked_mut(i)
+ }
+}
+
+#[test]
+fn zipslices() {
+
+ let xs = [1, 2, 3, 4, 5, 6];
+ let ys = [1, 2, 3, 7];
+ ::itertools::assert_equal(ZipSlices::new(&xs, &ys), xs.iter().zip(&ys));
+
+ let xs = [1, 2, 3, 4, 5, 6];
+ let mut ys = [0; 6];
+ for (x, y) in ZipSlices::from_slices(&xs[..], &mut ys[..]) {
+ *y = *x;
+ }
+ ::itertools::assert_equal(&xs, &ys);
+}
--- /dev/null
+use criterion::{criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+struct Unspecialized<I>(I);
+
+impl<I> Iterator for Unspecialized<I>
+where I: Iterator
+{
+ type Item = I::Item;
+
+ #[inline(always)]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.0.next()
+ }
+
+ #[inline(always)]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.0.size_hint()
+ }
+}
+
+mod specialization {
+ use super::*;
+
+ pub mod intersperse {
+ use super::*;
+
+ pub fn external(c: &mut Criterion)
+ {
+ let arr = [1; 1024];
+
+ c.bench_function("external", move |b| {
+ b.iter(|| {
+ let mut sum = 0;
+ for &x in arr.iter().intersperse(&0) {
+ sum += x;
+ }
+ sum
+ })
+ });
+ }
+
+ pub fn internal_specialized(c: &mut Criterion)
+ {
+ let arr = [1; 1024];
+
+ c.bench_function("internal specialized", move |b| {
+ b.iter(|| {
+ arr.iter().intersperse(&0).fold(0, |acc, x| acc + x)
+ })
+ });
+ }
+
+ pub fn internal_unspecialized(c: &mut Criterion)
+ {
+ let arr = [1; 1024];
+
+ c.bench_function("internal unspecialized", move |b| {
+ b.iter(|| {
+ Unspecialized(arr.iter().intersperse(&0)).fold(0, |acc, x| acc + x)
+ })
+ });
+ }
+ }
+}
+
+criterion_group!(
+ benches,
+ specialization::intersperse::external,
+ specialization::intersperse::internal_specialized,
+ specialization::intersperse::internal_unspecialized,
+);
+criterion_main!(benches);
--- /dev/null
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+// Keep aggregate generated elements the same, regardless of powerset length.
+const TOTAL_ELEMENTS: usize = 1 << 12;
+const fn calc_iters(n: usize) -> usize {
+ TOTAL_ELEMENTS / (1 << n)
+}
+
+fn powerset_n(c: &mut Criterion, n: usize) {
+ let id = format!("powerset {}", n);
+ c.bench_function(id.as_str(), move |b| {
+ b.iter(|| {
+ for _ in 0..calc_iters(n) {
+ for elt in (0..n).powerset() {
+ black_box(elt);
+ }
+ }
+ })
+ });
+}
+
+fn powerset_0(c: &mut Criterion) { powerset_n(c, 0); }
+
+fn powerset_1(c: &mut Criterion) { powerset_n(c, 1); }
+
+fn powerset_2(c: &mut Criterion) { powerset_n(c, 2); }
+
+fn powerset_4(c: &mut Criterion) { powerset_n(c, 4); }
+
+fn powerset_8(c: &mut Criterion) { powerset_n(c, 8); }
+
+fn powerset_12(c: &mut Criterion) { powerset_n(c, 12); }
+
+criterion_group!(
+ benches,
+ powerset_0,
+ powerset_1,
+ powerset_2,
+ powerset_4,
+ powerset_8,
+ powerset_12,
+);
+criterion_main!(benches);
\ No newline at end of file
--- /dev/null
+use criterion::{criterion_group, criterion_main, Criterion};
+use itertools::{Itertools, cloned};
+
+trait IterEx : Iterator {
+ // Another efficient implementation against which to compare,
+ // but needs `std` so is less desirable.
+ fn tree_fold1_vec<F>(self, mut f: F) -> Option<Self::Item>
+ where F: FnMut(Self::Item, Self::Item) -> Self::Item,
+ Self: Sized,
+ {
+ let hint = self.size_hint().0;
+ let cap = std::mem::size_of::<usize>() * 8 - hint.leading_zeros() as usize;
+ let mut stack = Vec::with_capacity(cap);
+ self.enumerate().for_each(|(mut i, mut x)| {
+ while (i & 1) != 0 {
+ x = f(stack.pop().unwrap(), x);
+ i >>= 1;
+ }
+ stack.push(x);
+ });
+ stack.into_iter().fold1(f)
+ }
+}
+impl<T:Iterator> IterEx for T {}
+
+macro_rules! def_benchs {
+ ($N:expr,
+ $FUN:ident,
+ $BENCH_NAME:ident,
+ ) => (
+ mod $BENCH_NAME {
+ use super::*;
+
+ pub fn sum(c: &mut Criterion) {
+ let v: Vec<u32> = (0.. $N).collect();
+
+ c.bench_function(&(stringify!($BENCH_NAME).replace('_', " ") + " sum"), move |b| {
+ b.iter(|| {
+ cloned(&v).$FUN(|x, y| x + y)
+ })
+ });
+ }
+
+ pub fn complex_iter(c: &mut Criterion) {
+ let u = (3..).take($N / 2);
+ let v = (5..).take($N / 2);
+ let it = u.chain(v);
+
+ c.bench_function(&(stringify!($BENCH_NAME).replace('_', " ") + " complex iter"), move |b| {
+ b.iter(|| {
+ it.clone().map(|x| x as f32).$FUN(f32::atan2)
+ })
+ });
+ }
+
+ pub fn string_format(c: &mut Criterion) {
+ // This goes quadratic with linear `fold1`, so use a smaller
+ // size to not waste too much time in travis. The allocations
+ // in here are so expensive anyway that it'll still take
+ // way longer per iteration than the other two benchmarks.
+ let v: Vec<u32> = (0.. ($N/4)).collect();
+
+ c.bench_function(&(stringify!($BENCH_NAME).replace('_', " ") + " string format"), move |b| {
+ b.iter(|| {
+ cloned(&v).map(|x| x.to_string()).$FUN(|x, y| format!("{} + {}", x, y))
+ })
+ });
+ }
+ }
+
+ criterion_group!(
+ $BENCH_NAME,
+ $BENCH_NAME::sum,
+ $BENCH_NAME::complex_iter,
+ $BENCH_NAME::string_format,
+ );
+ )
+}
+
+def_benchs!{
+ 10_000,
+ fold1,
+ fold1_10k,
+}
+
+def_benchs!{
+ 10_000,
+ tree_fold1,
+ tree_fold1_stack_10k,
+}
+
+def_benchs!{
+ 10_000,
+ tree_fold1_vec,
+ tree_fold1_vec_10k,
+}
+
+def_benchs!{
+ 100,
+ fold1,
+ fold1_100,
+}
+
+def_benchs!{
+ 100,
+ tree_fold1,
+ tree_fold1_stack_100,
+}
+
+def_benchs!{
+ 100,
+ tree_fold1_vec,
+ tree_fold1_vec_100,
+}
+
+def_benchs!{
+ 8,
+ fold1,
+ fold1_08,
+}
+
+def_benchs!{
+ 8,
+ tree_fold1,
+ tree_fold1_stack_08,
+}
+
+def_benchs!{
+ 8,
+ tree_fold1_vec,
+ tree_fold1_vec_08,
+}
+
+criterion_main!(
+ fold1_10k,
+ tree_fold1_stack_10k,
+ tree_fold1_vec_10k,
+ fold1_100,
+ tree_fold1_stack_100,
+ tree_fold1_vec_100,
+ fold1_08,
+ tree_fold1_stack_08,
+ tree_fold1_vec_08,
+);
--- /dev/null
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+// approximate 100_000 iterations for each combination
+const N1: usize = 100_000;
+const N2: usize = 448;
+const N3: usize = 86;
+const N4: usize = 41;
+
+fn tuple_comb_for1(c: &mut Criterion) {
+ c.bench_function("tuple comb for1", move |b| {
+ b.iter(|| {
+ for i in 0..N1 {
+ black_box(i);
+ }
+ })
+ });
+}
+
+fn tuple_comb_for2(c: &mut Criterion) {
+ c.bench_function("tuple comb for2", move |b| {
+ b.iter(|| {
+ for i in 0..N2 {
+ for j in (i + 1)..N2 {
+ black_box(i + j);
+ }
+ }
+ })
+ });
+}
+
+fn tuple_comb_for3(c: &mut Criterion) {
+ c.bench_function("tuple comb for3", move |b| {
+ b.iter(|| {
+ for i in 0..N3 {
+ for j in (i + 1)..N3 {
+ for k in (j + 1)..N3 {
+ black_box(i + j + k);
+ }
+ }
+ }
+ })
+ });
+}
+
+fn tuple_comb_for4(c: &mut Criterion) {
+ c.bench_function("tuple comb for4", move |b| {
+ b.iter(|| {
+ for i in 0..N4 {
+ for j in (i + 1)..N4 {
+ for k in (j + 1)..N4 {
+ for l in (k + 1)..N4 {
+ black_box(i + j + k + l);
+ }
+ }
+ }
+ }
+ })
+ });
+}
+
+fn tuple_comb_c1(c: &mut Criterion) {
+ c.bench_function("tuple comb c1", move |b| {
+ b.iter(|| {
+ for (i,) in (0..N1).tuple_combinations() {
+ black_box(i);
+ }
+ })
+ });
+}
+
+fn tuple_comb_c2(c: &mut Criterion) {
+ c.bench_function("tuple comb c2", move |b| {
+ b.iter(|| {
+ for (i, j) in (0..N2).tuple_combinations() {
+ black_box(i + j);
+ }
+ })
+ });
+}
+
+fn tuple_comb_c3(c: &mut Criterion) {
+ c.bench_function("tuple comb c3", move |b| {
+ b.iter(|| {
+ for (i, j, k) in (0..N3).tuple_combinations() {
+ black_box(i + j + k);
+ }
+ })
+ });
+}
+
+fn tuple_comb_c4(c: &mut Criterion) {
+ c.bench_function("tuple comb c4", move |b| {
+ b.iter(|| {
+ for (i, j, k, l) in (0..N4).tuple_combinations() {
+ black_box(i + j + k + l);
+ }
+ })
+ });
+}
+
+criterion_group!(
+ benches,
+ tuple_comb_for1,
+ tuple_comb_for2,
+ tuple_comb_for3,
+ tuple_comb_for4,
+ tuple_comb_c1,
+ tuple_comb_c2,
+ tuple_comb_c3,
+ tuple_comb_c4,
+);
+criterion_main!(benches);
--- /dev/null
+use criterion::{criterion_group, criterion_main, Criterion};
+use itertools::Itertools;
+
+fn s1(a: u32) -> u32 {
+ a
+}
+
+fn s2(a: u32, b: u32) -> u32 {
+ a + b
+}
+
+fn s3(a: u32, b: u32, c: u32) -> u32 {
+ a + b + c
+}
+
+fn s4(a: u32, b: u32, c: u32, d: u32) -> u32 {
+ a + b + c + d
+}
+
+fn sum_s1(s: &[u32]) -> u32 {
+ s1(s[0])
+}
+
+fn sum_s2(s: &[u32]) -> u32 {
+ s2(s[0], s[1])
+}
+
+fn sum_s3(s: &[u32]) -> u32 {
+ s3(s[0], s[1], s[2])
+}
+
+fn sum_s4(s: &[u32]) -> u32 {
+ s4(s[0], s[1], s[2], s[3])
+}
+
+fn sum_t1(s: &(&u32, )) -> u32 {
+ s1(*s.0)
+}
+
+fn sum_t2(s: &(&u32, &u32)) -> u32 {
+ s2(*s.0, *s.1)
+}
+
+fn sum_t3(s: &(&u32, &u32, &u32)) -> u32 {
+ s3(*s.0, *s.1, *s.2)
+}
+
+fn sum_t4(s: &(&u32, &u32, &u32, &u32)) -> u32 {
+ s4(*s.0, *s.1, *s.2, *s.3)
+}
+
+macro_rules! def_benchs {
+ ($N:expr;
+ $BENCH_GROUP:ident,
+ $TUPLE_FUN:ident,
+ $TUPLES:ident,
+ $TUPLE_WINDOWS:ident;
+ $SLICE_FUN:ident,
+ $CHUNKS:ident,
+ $WINDOWS:ident;
+ $FOR_CHUNKS:ident,
+ $FOR_WINDOWS:ident
+ ) => (
+ fn $FOR_CHUNKS(c: &mut Criterion) {
+ let v: Vec<u32> = (0.. $N * 1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($FOR_CHUNKS).replace('_', " "), move |b| {
+ b.iter(|| {
+ let mut j = 0;
+ for _ in 0..1_000 {
+ s += $SLICE_FUN(&v[j..(j + $N)]);
+ j += $N;
+ }
+ s
+ })
+ });
+ }
+
+ fn $FOR_WINDOWS(c: &mut Criterion) {
+ let v: Vec<u32> = (0..1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($FOR_WINDOWS).replace('_', " "), move |b| {
+ b.iter(|| {
+ for i in 0..(1_000 - $N) {
+ s += $SLICE_FUN(&v[i..(i + $N)]);
+ }
+ s
+ })
+ });
+ }
+
+ fn $TUPLES(c: &mut Criterion) {
+ let v: Vec<u32> = (0.. $N * 1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($TUPLES).replace('_', " "), move |b| {
+ b.iter(|| {
+ for x in v.iter().tuples() {
+ s += $TUPLE_FUN(&x);
+ }
+ s
+ })
+ });
+ }
+
+ fn $CHUNKS(c: &mut Criterion) {
+ let v: Vec<u32> = (0.. $N * 1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($CHUNKS).replace('_', " "), move |b| {
+ b.iter(|| {
+ for x in v.chunks($N) {
+ s += $SLICE_FUN(x);
+ }
+ s
+ })
+ });
+ }
+
+ fn $TUPLE_WINDOWS(c: &mut Criterion) {
+ let v: Vec<u32> = (0..1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($TUPLE_WINDOWS).replace('_', " "), move |b| {
+ b.iter(|| {
+ for x in v.iter().tuple_windows() {
+ s += $TUPLE_FUN(&x);
+ }
+ s
+ })
+ });
+ }
+
+ fn $WINDOWS(c: &mut Criterion) {
+ let v: Vec<u32> = (0..1_000).collect();
+ let mut s = 0;
+ c.bench_function(&stringify!($WINDOWS).replace('_', " "), move |b| {
+ b.iter(|| {
+ for x in v.windows($N) {
+ s += $SLICE_FUN(x);
+ }
+ s
+ })
+ });
+ }
+
+ criterion_group!(
+ $BENCH_GROUP,
+ $FOR_CHUNKS,
+ $FOR_WINDOWS,
+ $TUPLES,
+ $CHUNKS,
+ $TUPLE_WINDOWS,
+ $WINDOWS,
+ );
+ )
+}
+
+def_benchs!{
+ 1;
+ benches_1,
+ sum_t1,
+ tuple_chunks_1,
+ tuple_windows_1;
+ sum_s1,
+ slice_chunks_1,
+ slice_windows_1;
+ for_chunks_1,
+ for_windows_1
+}
+
+def_benchs!{
+ 2;
+ benches_2,
+ sum_t2,
+ tuple_chunks_2,
+ tuple_windows_2;
+ sum_s2,
+ slice_chunks_2,
+ slice_windows_2;
+ for_chunks_2,
+ for_windows_2
+}
+
+def_benchs!{
+ 3;
+ benches_3,
+ sum_t3,
+ tuple_chunks_3,
+ tuple_windows_3;
+ sum_s3,
+ slice_chunks_3,
+ slice_windows_3;
+ for_chunks_3,
+ for_windows_3
+}
+
+def_benchs!{
+ 4;
+ benches_4,
+ sum_t4,
+ tuple_chunks_4,
+ tuple_windows_4;
+ sum_s4,
+ slice_chunks_4,
+ slice_windows_4;
+ for_chunks_4,
+ for_windows_4
+}
+
+criterion_main!(
+ benches_1,
+ benches_2,
+ benches_3,
+ benches_4,
+);
--- /dev/null
+msrv = "1.36.0"
--- /dev/null
+5.1,3.5,1.4,0.2,Iris-setosa
+4.9,3.0,1.4,0.2,Iris-setosa
+4.7,3.2,1.3,0.2,Iris-setosa
+4.6,3.1,1.5,0.2,Iris-setosa
+5.0,3.6,1.4,0.2,Iris-setosa
+5.4,3.9,1.7,0.4,Iris-setosa
+4.6,3.4,1.4,0.3,Iris-setosa
+5.0,3.4,1.5,0.2,Iris-setosa
+4.4,2.9,1.4,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+5.4,3.7,1.5,0.2,Iris-setosa
+4.8,3.4,1.6,0.2,Iris-setosa
+4.8,3.0,1.4,0.1,Iris-setosa
+4.3,3.0,1.1,0.1,Iris-setosa
+5.8,4.0,1.2,0.2,Iris-setosa
+5.7,4.4,1.5,0.4,Iris-setosa
+5.4,3.9,1.3,0.4,Iris-setosa
+5.1,3.5,1.4,0.3,Iris-setosa
+5.7,3.8,1.7,0.3,Iris-setosa
+5.1,3.8,1.5,0.3,Iris-setosa
+5.4,3.4,1.7,0.2,Iris-setosa
+5.1,3.7,1.5,0.4,Iris-setosa
+4.6,3.6,1.0,0.2,Iris-setosa
+5.1,3.3,1.7,0.5,Iris-setosa
+4.8,3.4,1.9,0.2,Iris-setosa
+5.0,3.0,1.6,0.2,Iris-setosa
+5.0,3.4,1.6,0.4,Iris-setosa
+5.2,3.5,1.5,0.2,Iris-setosa
+5.2,3.4,1.4,0.2,Iris-setosa
+4.7,3.2,1.6,0.2,Iris-setosa
+4.8,3.1,1.6,0.2,Iris-setosa
+5.4,3.4,1.5,0.4,Iris-setosa
+5.2,4.1,1.5,0.1,Iris-setosa
+5.5,4.2,1.4,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+5.0,3.2,1.2,0.2,Iris-setosa
+5.5,3.5,1.3,0.2,Iris-setosa
+4.9,3.1,1.5,0.1,Iris-setosa
+4.4,3.0,1.3,0.2,Iris-setosa
+5.1,3.4,1.5,0.2,Iris-setosa
+5.0,3.5,1.3,0.3,Iris-setosa
+4.5,2.3,1.3,0.3,Iris-setosa
+4.4,3.2,1.3,0.2,Iris-setosa
+5.0,3.5,1.6,0.6,Iris-setosa
+5.1,3.8,1.9,0.4,Iris-setosa
+4.8,3.0,1.4,0.3,Iris-setosa
+5.1,3.8,1.6,0.2,Iris-setosa
+4.6,3.2,1.4,0.2,Iris-setosa
+5.3,3.7,1.5,0.2,Iris-setosa
+5.0,3.3,1.4,0.2,Iris-setosa
+7.0,3.2,4.7,1.4,Iris-versicolor
+6.4,3.2,4.5,1.5,Iris-versicolor
+6.9,3.1,4.9,1.5,Iris-versicolor
+5.5,2.3,4.0,1.3,Iris-versicolor
+6.5,2.8,4.6,1.5,Iris-versicolor
+5.7,2.8,4.5,1.3,Iris-versicolor
+6.3,3.3,4.7,1.6,Iris-versicolor
+4.9,2.4,3.3,1.0,Iris-versicolor
+6.6,2.9,4.6,1.3,Iris-versicolor
+5.2,2.7,3.9,1.4,Iris-versicolor
+5.0,2.0,3.5,1.0,Iris-versicolor
+5.9,3.0,4.2,1.5,Iris-versicolor
+6.0,2.2,4.0,1.0,Iris-versicolor
+6.1,2.9,4.7,1.4,Iris-versicolor
+5.6,2.9,3.6,1.3,Iris-versicolor
+6.7,3.1,4.4,1.4,Iris-versicolor
+5.6,3.0,4.5,1.5,Iris-versicolor
+5.8,2.7,4.1,1.0,Iris-versicolor
+6.2,2.2,4.5,1.5,Iris-versicolor
+5.6,2.5,3.9,1.1,Iris-versicolor
+5.9,3.2,4.8,1.8,Iris-versicolor
+6.1,2.8,4.0,1.3,Iris-versicolor
+6.3,2.5,4.9,1.5,Iris-versicolor
+6.1,2.8,4.7,1.2,Iris-versicolor
+6.4,2.9,4.3,1.3,Iris-versicolor
+6.6,3.0,4.4,1.4,Iris-versicolor
+6.8,2.8,4.8,1.4,Iris-versicolor
+6.7,3.0,5.0,1.7,Iris-versicolor
+6.0,2.9,4.5,1.5,Iris-versicolor
+5.7,2.6,3.5,1.0,Iris-versicolor
+5.5,2.4,3.8,1.1,Iris-versicolor
+5.5,2.4,3.7,1.0,Iris-versicolor
+5.8,2.7,3.9,1.2,Iris-versicolor
+6.0,2.7,5.1,1.6,Iris-versicolor
+5.4,3.0,4.5,1.5,Iris-versicolor
+6.0,3.4,4.5,1.6,Iris-versicolor
+6.7,3.1,4.7,1.5,Iris-versicolor
+6.3,2.3,4.4,1.3,Iris-versicolor
+5.6,3.0,4.1,1.3,Iris-versicolor
+5.5,2.5,4.0,1.3,Iris-versicolor
+5.5,2.6,4.4,1.2,Iris-versicolor
+6.1,3.0,4.6,1.4,Iris-versicolor
+5.8,2.6,4.0,1.2,Iris-versicolor
+5.0,2.3,3.3,1.0,Iris-versicolor
+5.6,2.7,4.2,1.3,Iris-versicolor
+5.7,3.0,4.2,1.2,Iris-versicolor
+5.7,2.9,4.2,1.3,Iris-versicolor
+6.2,2.9,4.3,1.3,Iris-versicolor
+5.1,2.5,3.0,1.1,Iris-versicolor
+5.7,2.8,4.1,1.3,Iris-versicolor
+6.3,3.3,6.0,2.5,Iris-virginica
+5.8,2.7,5.1,1.9,Iris-virginica
+7.1,3.0,5.9,2.1,Iris-virginica
+6.3,2.9,5.6,1.8,Iris-virginica
+6.5,3.0,5.8,2.2,Iris-virginica
+7.6,3.0,6.6,2.1,Iris-virginica
+4.9,2.5,4.5,1.7,Iris-virginica
+7.3,2.9,6.3,1.8,Iris-virginica
+6.7,2.5,5.8,1.8,Iris-virginica
+7.2,3.6,6.1,2.5,Iris-virginica
+6.5,3.2,5.1,2.0,Iris-virginica
+6.4,2.7,5.3,1.9,Iris-virginica
+6.8,3.0,5.5,2.1,Iris-virginica
+5.7,2.5,5.0,2.0,Iris-virginica
+5.8,2.8,5.1,2.4,Iris-virginica
+6.4,3.2,5.3,2.3,Iris-virginica
+6.5,3.0,5.5,1.8,Iris-virginica
+7.7,3.8,6.7,2.2,Iris-virginica
+7.7,2.6,6.9,2.3,Iris-virginica
+6.0,2.2,5.0,1.5,Iris-virginica
+6.9,3.2,5.7,2.3,Iris-virginica
+5.6,2.8,4.9,2.0,Iris-virginica
+7.7,2.8,6.7,2.0,Iris-virginica
+6.3,2.7,4.9,1.8,Iris-virginica
+6.7,3.3,5.7,2.1,Iris-virginica
+7.2,3.2,6.0,1.8,Iris-virginica
+6.2,2.8,4.8,1.8,Iris-virginica
+6.1,3.0,4.9,1.8,Iris-virginica
+6.4,2.8,5.6,2.1,Iris-virginica
+7.2,3.0,5.8,1.6,Iris-virginica
+7.4,2.8,6.1,1.9,Iris-virginica
+7.9,3.8,6.4,2.0,Iris-virginica
+6.4,2.8,5.6,2.2,Iris-virginica
+6.3,2.8,5.1,1.5,Iris-virginica
+6.1,2.6,5.6,1.4,Iris-virginica
+7.7,3.0,6.1,2.3,Iris-virginica
+6.3,3.4,5.6,2.4,Iris-virginica
+6.4,3.1,5.5,1.8,Iris-virginica
+6.0,3.0,4.8,1.8,Iris-virginica
+6.9,3.1,5.4,2.1,Iris-virginica
+6.7,3.1,5.6,2.4,Iris-virginica
+6.9,3.1,5.1,2.3,Iris-virginica
+5.8,2.7,5.1,1.9,Iris-virginica
+6.8,3.2,5.9,2.3,Iris-virginica
+6.7,3.3,5.7,2.5,Iris-virginica
+6.7,3.0,5.2,2.3,Iris-virginica
+6.3,2.5,5.0,1.9,Iris-virginica
+6.5,3.0,5.2,2.0,Iris-virginica
+6.2,3.4,5.4,2.3,Iris-virginica
+5.9,3.0,5.1,1.8,Iris-virginica
--- /dev/null
+///
+/// This example parses, sorts and groups the iris dataset
+/// and does some simple manipulations.
+///
+/// Iterators and itertools functionality are used throughout.
+
+use itertools::Itertools;
+use std::collections::HashMap;
+use std::iter::repeat;
+use std::num::ParseFloatError;
+use std::str::FromStr;
+
+static DATA: &'static str = include_str!("iris.data");
+
+#[derive(Clone, Debug)]
+struct Iris {
+ name: String,
+ data: [f32; 4],
+}
+
+#[derive(Clone, Debug)]
+enum ParseError {
+ Numeric(ParseFloatError),
+ Other(&'static str),
+}
+
+impl From<ParseFloatError> for ParseError {
+ fn from(err: ParseFloatError) -> Self {
+ ParseError::Numeric(err)
+ }
+}
+
+/// Parse an Iris from a comma-separated line
+impl FromStr for Iris {
+ type Err = ParseError;
+
+ fn from_str(s: &str) -> Result<Self, Self::Err> {
+ let mut iris = Iris { name: "".into(), data: [0.; 4] };
+ let mut parts = s.split(",").map(str::trim);
+
+ // using Iterator::by_ref()
+ for (index, part) in parts.by_ref().take(4).enumerate() {
+ iris.data[index] = part.parse::<f32>()?;
+ }
+ if let Some(name) = parts.next() {
+ iris.name = name.into();
+ } else {
+ return Err(ParseError::Other("Missing name"))
+ }
+ Ok(iris)
+ }
+}
+
+fn main() {
+ // using Itertools::fold_results to create the result of parsing
+ let irises = DATA.lines()
+ .map(str::parse)
+ .fold_ok(Vec::new(), |mut v, iris: Iris| {
+ v.push(iris);
+ v
+ });
+ let mut irises = match irises {
+ Err(e) => {
+ println!("Error parsing: {:?}", e);
+ std::process::exit(1);
+ }
+ Ok(data) => data,
+ };
+
+ // Sort them and group them
+ irises.sort_by(|a, b| Ord::cmp(&a.name, &b.name));
+
+ // using Iterator::cycle()
+ let mut plot_symbols = "+ox".chars().cycle();
+ let mut symbolmap = HashMap::new();
+
+ // using Itertools::group_by
+ for (species, species_group) in &irises.iter().group_by(|iris| &iris.name) {
+ // assign a plot symbol
+ symbolmap.entry(species).or_insert_with(|| {
+ plot_symbols.next().unwrap()
+ });
+ println!("{} (symbol={})", species, symbolmap[species]);
+
+ for iris in species_group {
+ // using Itertools::format for lazy formatting
+ println!("{:>3.1}", iris.data.iter().format(", "));
+ }
+
+ }
+
+ // Look at all combinations of the four columns
+ //
+ // See https://en.wikipedia.org/wiki/Iris_flower_data_set
+ //
+ let n = 30; // plot size
+ let mut plot = vec![' '; n * n];
+
+ // using Itertools::tuple_combinations
+ for (a, b) in (0..4).tuple_combinations() {
+ println!("Column {} vs {}:", a, b);
+
+ // Clear plot
+ //
+ // using std::iter::repeat;
+ // using Itertools::set_from
+ plot.iter_mut().set_from(repeat(' '));
+
+ // using Itertools::minmax
+ let min_max = |data: &[Iris], col| {
+ data.iter()
+ .map(|iris| iris.data[col])
+ .minmax()
+ .into_option()
+ .expect("Can't find min/max of empty iterator")
+ };
+ let (min_x, max_x) = min_max(&irises, a);
+ let (min_y, max_y) = min_max(&irises, b);
+
+ // Plot the data points
+ let round_to_grid = |x, min, max| ((x - min) / (max - min) * ((n - 1) as f32)) as usize;
+ let flip = |ix| n - 1 - ix; // reverse axis direction
+
+ for iris in &irises {
+ let ix = round_to_grid(iris.data[a], min_x, max_x);
+ let iy = flip(round_to_grid(iris.data[b], min_y, max_y));
+ plot[n * iy + ix] = symbolmap[&iris.name];
+ }
+
+ // render plot
+ //
+ // using Itertools::join
+ for line in plot.chunks(n) {
+ println!("{}", line.iter().join(" "))
+ }
+ }
+}
--- /dev/null
+use std::fmt;
+use std::iter::FusedIterator;
+
+use crate::size_hint;
+
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct CoalesceBy<I, F, T>
+where
+ I: Iterator,
+{
+ iter: I,
+ last: Option<T>,
+ f: F,
+}
+
+impl<I: Clone, F: Clone, T: Clone> Clone for CoalesceBy<I, F, T>
+where
+ I: Iterator,
+{
+ clone_fields!(last, iter, f);
+}
+
+impl<I, F, T> fmt::Debug for CoalesceBy<I, F, T>
+where
+ I: Iterator + fmt::Debug,
+ T: fmt::Debug,
+{
+ debug_fmt_fields!(CoalesceBy, iter);
+}
+
+pub trait CoalescePredicate<Item, T> {
+ fn coalesce_pair(&mut self, t: T, item: Item) -> Result<T, (T, T)>;
+}
+
+impl<I, F, T> Iterator for CoalesceBy<I, F, T>
+where
+ I: Iterator,
+ F: CoalescePredicate<I::Item, T>,
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ // this fuses the iterator
+ let last = self.last.take()?;
+
+ let self_last = &mut self.last;
+ let self_f = &mut self.f;
+ Some(
+ self.iter
+ .try_fold(last, |last, next| match self_f.coalesce_pair(last, next) {
+ Ok(joined) => Ok(joined),
+ Err((last_, next_)) => {
+ *self_last = Some(next_);
+ Err(last_)
+ }
+ })
+ .unwrap_or_else(|x| x),
+ )
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (low, hi) = size_hint::add_scalar(self.iter.size_hint(), self.last.is_some() as usize);
+ ((low > 0) as usize, hi)
+ }
+
+ fn fold<Acc, FnAcc>(self, acc: Acc, mut fn_acc: FnAcc) -> Acc
+ where
+ FnAcc: FnMut(Acc, Self::Item) -> Acc,
+ {
+ if let Some(last) = self.last {
+ let mut f = self.f;
+ let (last, acc) = self.iter.fold((last, acc), |(last, acc), elt| {
+ match f.coalesce_pair(last, elt) {
+ Ok(joined) => (joined, acc),
+ Err((last_, next_)) => (next_, fn_acc(acc, last_)),
+ }
+ });
+ fn_acc(acc, last)
+ } else {
+ acc
+ }
+ }
+}
+
+impl<I: Iterator, F: CoalescePredicate<I::Item, T>, T> FusedIterator for CoalesceBy<I, F, T> {}
+
+/// An iterator adaptor that may join together adjacent elements.
+///
+/// See [`.coalesce()`](crate::Itertools::coalesce) for more information.
+pub type Coalesce<I, F> = CoalesceBy<I, F, <I as Iterator>::Item>;
+
+impl<F, Item, T> CoalescePredicate<Item, T> for F
+where
+ F: FnMut(T, Item) -> Result<T, (T, T)>,
+{
+ fn coalesce_pair(&mut self, t: T, item: Item) -> Result<T, (T, T)> {
+ self(t, item)
+ }
+}
+
+/// Create a new `Coalesce`.
+pub fn coalesce<I, F>(mut iter: I, f: F) -> Coalesce<I, F>
+where
+ I: Iterator,
+{
+ Coalesce {
+ last: iter.next(),
+ iter,
+ f,
+ }
+}
+
+/// An iterator adaptor that removes repeated duplicates, determining equality using a comparison function.
+///
+/// See [`.dedup_by()`](crate::Itertools::dedup_by) or [`.dedup()`](crate::Itertools::dedup) for more information.
+pub type DedupBy<I, Pred> = CoalesceBy<I, DedupPred2CoalescePred<Pred>, <I as Iterator>::Item>;
+
+#[derive(Clone)]
+pub struct DedupPred2CoalescePred<DP>(DP);
+
+impl<DP> fmt::Debug for DedupPred2CoalescePred<DP> {
+ debug_fmt_fields!(DedupPred2CoalescePred,);
+}
+
+pub trait DedupPredicate<T> {
+ // TODO replace by Fn(&T, &T)->bool once Rust supports it
+ fn dedup_pair(&mut self, a: &T, b: &T) -> bool;
+}
+
+impl<DP, T> CoalescePredicate<T, T> for DedupPred2CoalescePred<DP>
+where
+ DP: DedupPredicate<T>,
+{
+ fn coalesce_pair(&mut self, t: T, item: T) -> Result<T, (T, T)> {
+ if self.0.dedup_pair(&t, &item) {
+ Ok(t)
+ } else {
+ Err((t, item))
+ }
+ }
+}
+
+#[derive(Clone, Debug)]
+pub struct DedupEq;
+
+impl<T: PartialEq> DedupPredicate<T> for DedupEq {
+ fn dedup_pair(&mut self, a: &T, b: &T) -> bool {
+ a == b
+ }
+}
+
+impl<T, F: FnMut(&T, &T) -> bool> DedupPredicate<T> for F {
+ fn dedup_pair(&mut self, a: &T, b: &T) -> bool {
+ self(a, b)
+ }
+}
+
+/// Create a new `DedupBy`.
+pub fn dedup_by<I, Pred>(mut iter: I, dedup_pred: Pred) -> DedupBy<I, Pred>
+where
+ I: Iterator,
+{
+ DedupBy {
+ last: iter.next(),
+ iter,
+ f: DedupPred2CoalescePred(dedup_pred),
+ }
+}
+
+/// An iterator adaptor that removes repeated duplicates.
+///
+/// See [`.dedup()`](crate::Itertools::dedup) for more information.
+pub type Dedup<I> = DedupBy<I, DedupEq>;
+
+/// Create a new `Dedup`.
+pub fn dedup<I>(iter: I) -> Dedup<I>
+where
+ I: Iterator,
+{
+ dedup_by(iter, DedupEq)
+}
+
+/// An iterator adaptor that removes repeated duplicates, while keeping a count of how many
+/// repeated elements were present. This will determine equality using a comparison function.
+///
+/// See [`.dedup_by_with_count()`](crate::Itertools::dedup_by_with_count) or
+/// [`.dedup_with_count()`](crate::Itertools::dedup_with_count) for more information.
+pub type DedupByWithCount<I, Pred> =
+ CoalesceBy<I, DedupPredWithCount2CoalescePred<Pred>, (usize, <I as Iterator>::Item)>;
+
+#[derive(Clone, Debug)]
+pub struct DedupPredWithCount2CoalescePred<DP>(DP);
+
+impl<DP, T> CoalescePredicate<T, (usize, T)> for DedupPredWithCount2CoalescePred<DP>
+where
+ DP: DedupPredicate<T>,
+{
+ fn coalesce_pair(
+ &mut self,
+ (c, t): (usize, T),
+ item: T,
+ ) -> Result<(usize, T), ((usize, T), (usize, T))> {
+ if self.0.dedup_pair(&t, &item) {
+ Ok((c + 1, t))
+ } else {
+ Err(((c, t), (1, item)))
+ }
+ }
+}
+
+/// An iterator adaptor that removes repeated duplicates, while keeping a count of how many
+/// repeated elements were present.
+///
+/// See [`.dedup_with_count()`](crate::Itertools::dedup_with_count) for more information.
+pub type DedupWithCount<I> = DedupByWithCount<I, DedupEq>;
+
+/// Create a new `DedupByWithCount`.
+pub fn dedup_by_with_count<I, Pred>(mut iter: I, dedup_pred: Pred) -> DedupByWithCount<I, Pred>
+where
+ I: Iterator,
+{
+ DedupByWithCount {
+ last: iter.next().map(|v| (1, v)),
+ iter,
+ f: DedupPredWithCount2CoalescePred(dedup_pred),
+ }
+}
+
+/// Create a new `DedupWithCount`.
+pub fn dedup_with_count<I>(iter: I) -> DedupWithCount<I>
+where
+ I: Iterator,
+{
+ dedup_by_with_count(iter, DedupEq)
+}
--- /dev/null
+use std::iter::FromIterator;
+use std::marker::PhantomData;
+
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct MapSpecialCase<I, F> {
+ iter: I,
+ f: F,
+}
+
+pub trait MapSpecialCaseFn<T> {
+ type Out;
+ fn call(&mut self, t: T) -> Self::Out;
+}
+
+impl<I, R> Iterator for MapSpecialCase<I, R>
+where
+ I: Iterator,
+ R: MapSpecialCaseFn<I::Item>,
+{
+ type Item = R::Out;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.next().map(|i| self.f.call(i))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+
+ fn fold<Acc, Fold>(self, init: Acc, mut fold_f: Fold) -> Acc
+ where
+ Fold: FnMut(Acc, Self::Item) -> Acc,
+ {
+ let mut f = self.f;
+ self.iter.fold(init, move |acc, v| fold_f(acc, f.call(v)))
+ }
+
+ fn collect<C>(self) -> C
+ where
+ C: FromIterator<Self::Item>,
+ {
+ let mut f = self.f;
+ self.iter.map(move |v| f.call(v)).collect()
+ }
+}
+
+impl<I, R> DoubleEndedIterator for MapSpecialCase<I, R>
+where
+ I: DoubleEndedIterator,
+ R: MapSpecialCaseFn<I::Item>,
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.iter.next_back().map(|i| self.f.call(i))
+ }
+}
+
+impl<I, R> ExactSizeIterator for MapSpecialCase<I, R>
+where
+ I: ExactSizeIterator,
+ R: MapSpecialCaseFn<I::Item>,
+{
+}
+
+/// An iterator adapter to apply a transformation within a nested `Result::Ok`.
+///
+/// See [`.map_ok()`](crate::Itertools::map_ok) for more information.
+pub type MapOk<I, F> = MapSpecialCase<I, MapSpecialCaseFnOk<F>>;
+
+/// See [`MapOk`].
+#[deprecated(note = "Use MapOk instead", since = "0.10.0")]
+pub type MapResults<I, F> = MapOk<I, F>;
+
+impl<F, T, U, E> MapSpecialCaseFn<Result<T, E>> for MapSpecialCaseFnOk<F>
+where
+ F: FnMut(T) -> U,
+{
+ type Out = Result<U, E>;
+ fn call(&mut self, t: Result<T, E>) -> Self::Out {
+ t.map(|v| self.0(v))
+ }
+}
+
+#[derive(Clone)]
+pub struct MapSpecialCaseFnOk<F>(F);
+
+impl<F> std::fmt::Debug for MapSpecialCaseFnOk<F> {
+ debug_fmt_fields!(MapSpecialCaseFnOk,);
+}
+
+/// Create a new `MapOk` iterator.
+pub fn map_ok<I, F, T, U, E>(iter: I, f: F) -> MapOk<I, F>
+where
+ I: Iterator<Item = Result<T, E>>,
+ F: FnMut(T) -> U,
+{
+ MapSpecialCase {
+ iter,
+ f: MapSpecialCaseFnOk(f),
+ }
+}
+
+/// An iterator adapter to apply `Into` conversion to each element.
+///
+/// See [`.map_into()`](crate::Itertools::map_into) for more information.
+pub type MapInto<I, R> = MapSpecialCase<I, MapSpecialCaseFnInto<R>>;
+
+impl<T: Into<U>, U> MapSpecialCaseFn<T> for MapSpecialCaseFnInto<U> {
+ type Out = U;
+ fn call(&mut self, t: T) -> Self::Out {
+ t.into()
+ }
+}
+
+#[derive(Clone, Debug)]
+pub struct MapSpecialCaseFnInto<U>(PhantomData<U>);
+
+/// Create a new [`MapInto`] iterator.
+pub fn map_into<I, R>(iter: I) -> MapInto<I, R> {
+ MapSpecialCase {
+ iter,
+ f: MapSpecialCaseFnInto(PhantomData),
+ }
+}
--- /dev/null
+//! Licensed under the Apache License, Version 2.0
+//! <https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+//! <https://opensource.org/licenses/MIT>, at your
+//! option. This file may not be copied, modified, or distributed
+//! except according to those terms.
+
+mod coalesce;
+mod map;
+mod multi_product;
+pub use self::coalesce::*;
+pub use self::map::{map_into, map_ok, MapInto, MapOk};
+#[allow(deprecated)]
+pub use self::map::MapResults;
+#[cfg(feature = "use_alloc")]
+pub use self::multi_product::*;
+
+use std::fmt;
+use std::iter::{Fuse, Peekable, FromIterator, FusedIterator};
+use std::marker::PhantomData;
+use crate::size_hint;
+
+/// An iterator adaptor that alternates elements from two iterators until both
+/// run out.
+///
+/// This iterator is *fused*.
+///
+/// See [`.interleave()`](crate::Itertools::interleave) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Interleave<I, J> {
+ a: Fuse<I>,
+ b: Fuse<J>,
+ flag: bool,
+}
+
+/// Create an iterator that interleaves elements in `i` and `j`.
+///
+/// [`IntoIterator`] enabled version of `[Itertools::interleave]`.
+pub fn interleave<I, J>(i: I, j: J) -> Interleave<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
+ where I: IntoIterator,
+ J: IntoIterator<Item = I::Item>
+{
+ Interleave {
+ a: i.into_iter().fuse(),
+ b: j.into_iter().fuse(),
+ flag: false,
+ }
+}
+
+impl<I, J> Iterator for Interleave<I, J>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.flag = !self.flag;
+ if self.flag {
+ match self.a.next() {
+ None => self.b.next(),
+ r => r,
+ }
+ } else {
+ match self.b.next() {
+ None => self.a.next(),
+ r => r,
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add(self.a.size_hint(), self.b.size_hint())
+ }
+}
+
+impl<I, J> FusedIterator for Interleave<I, J>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{}
+
+/// An iterator adaptor that alternates elements from the two iterators until
+/// one of them runs out.
+///
+/// This iterator is *fused*.
+///
+/// See [`.interleave_shortest()`](crate::Itertools::interleave_shortest)
+/// for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct InterleaveShortest<I, J>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{
+ it0: I,
+ it1: J,
+ phase: bool, // false ==> it0, true ==> it1
+}
+
+/// Create a new `InterleaveShortest` iterator.
+pub fn interleave_shortest<I, J>(a: I, b: J) -> InterleaveShortest<I, J>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{
+ InterleaveShortest {
+ it0: a,
+ it1: b,
+ phase: false,
+ }
+}
+
+impl<I, J> Iterator for InterleaveShortest<I, J>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{
+ type Item = I::Item;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ let e = if self.phase { self.it1.next() } else { self.it0.next() };
+ if e.is_some() {
+ self.phase = !self.phase;
+ }
+ e
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (curr_hint, next_hint) = {
+ let it0_hint = self.it0.size_hint();
+ let it1_hint = self.it1.size_hint();
+ if self.phase {
+ (it1_hint, it0_hint)
+ } else {
+ (it0_hint, it1_hint)
+ }
+ };
+ let (curr_lower, curr_upper) = curr_hint;
+ let (next_lower, next_upper) = next_hint;
+ let (combined_lower, combined_upper) =
+ size_hint::mul_scalar(size_hint::min(curr_hint, next_hint), 2);
+ let lower =
+ if curr_lower > next_lower {
+ combined_lower + 1
+ } else {
+ combined_lower
+ };
+ let upper = {
+ let extra_elem = match (curr_upper, next_upper) {
+ (_, None) => false,
+ (None, Some(_)) => true,
+ (Some(curr_max), Some(next_max)) => curr_max > next_max,
+ };
+ if extra_elem {
+ combined_upper.and_then(|x| x.checked_add(1))
+ } else {
+ combined_upper
+ }
+ };
+ (lower, upper)
+ }
+}
+
+impl<I, J> FusedIterator for InterleaveShortest<I, J>
+ where I: FusedIterator,
+ J: FusedIterator<Item = I::Item>
+{}
+
+#[derive(Clone, Debug)]
+/// An iterator adaptor that allows putting back a single
+/// item to the front of the iterator.
+///
+/// Iterator element type is `I::Item`.
+pub struct PutBack<I>
+ where I: Iterator
+{
+ top: Option<I::Item>,
+ iter: I,
+}
+
+/// Create an iterator where you can put back a single item
+pub fn put_back<I>(iterable: I) -> PutBack<I::IntoIter>
+ where I: IntoIterator
+{
+ PutBack {
+ top: None,
+ iter: iterable.into_iter(),
+ }
+}
+
+impl<I> PutBack<I>
+ where I: Iterator
+{
+ /// put back value `value` (builder method)
+ pub fn with_value(mut self, value: I::Item) -> Self {
+ self.put_back(value);
+ self
+ }
+
+ /// Split the `PutBack` into its parts.
+ #[inline]
+ pub fn into_parts(self) -> (Option<I::Item>, I) {
+ let PutBack{top, iter} = self;
+ (top, iter)
+ }
+
+ /// Put back a single value to the front of the iterator.
+ ///
+ /// If a value is already in the put back slot, it is overwritten.
+ #[inline]
+ pub fn put_back(&mut self, x: I::Item) {
+ self.top = Some(x);
+ }
+}
+
+impl<I> Iterator for PutBack<I>
+ where I: Iterator
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.top {
+ None => self.iter.next(),
+ ref mut some => some.take(),
+ }
+ }
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // Not ExactSizeIterator because size may be larger than usize
+ size_hint::add_scalar(self.iter.size_hint(), self.top.is_some() as usize)
+ }
+
+ fn count(self) -> usize {
+ self.iter.count() + (self.top.is_some() as usize)
+ }
+
+ fn last(self) -> Option<Self::Item> {
+ self.iter.last().or(self.top)
+ }
+
+ fn nth(&mut self, n: usize) -> Option<Self::Item> {
+ match self.top {
+ None => self.iter.nth(n),
+ ref mut some => {
+ if n == 0 {
+ some.take()
+ } else {
+ *some = None;
+ self.iter.nth(n - 1)
+ }
+ }
+ }
+ }
+
+ fn all<G>(&mut self, mut f: G) -> bool
+ where G: FnMut(Self::Item) -> bool
+ {
+ if let Some(elt) = self.top.take() {
+ if !f(elt) {
+ return false;
+ }
+ }
+ self.iter.all(f)
+ }
+
+ fn fold<Acc, G>(mut self, init: Acc, mut f: G) -> Acc
+ where G: FnMut(Acc, Self::Item) -> Acc,
+ {
+ let mut accum = init;
+ if let Some(elt) = self.top.take() {
+ accum = f(accum, elt);
+ }
+ self.iter.fold(accum, f)
+ }
+}
+
+#[derive(Debug, Clone)]
+/// An iterator adaptor that iterates over the cartesian product of
+/// the element sets of two iterators `I` and `J`.
+///
+/// Iterator element type is `(I::Item, J::Item)`.
+///
+/// See [`.cartesian_product()`](crate::Itertools::cartesian_product) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Product<I, J>
+ where I: Iterator
+{
+ a: I,
+ a_cur: Option<I::Item>,
+ b: J,
+ b_orig: J,
+}
+
+/// Create a new cartesian product iterator
+///
+/// Iterator element type is `(I::Item, J::Item)`.
+pub fn cartesian_product<I, J>(mut i: I, j: J) -> Product<I, J>
+ where I: Iterator,
+ J: Clone + Iterator,
+ I::Item: Clone
+{
+ Product {
+ a_cur: i.next(),
+ a: i,
+ b: j.clone(),
+ b_orig: j,
+ }
+}
+
+impl<I, J> Iterator for Product<I, J>
+ where I: Iterator,
+ J: Clone + Iterator,
+ I::Item: Clone
+{
+ type Item = (I::Item, J::Item);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let elt_b = match self.b.next() {
+ None => {
+ self.b = self.b_orig.clone();
+ match self.b.next() {
+ None => return None,
+ Some(x) => {
+ self.a_cur = self.a.next();
+ x
+ }
+ }
+ }
+ Some(x) => x
+ };
+ self.a_cur.as_ref().map(|a| (a.clone(), elt_b))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let has_cur = self.a_cur.is_some() as usize;
+ // Not ExactSizeIterator because size may be larger than usize
+ let (b_min, b_max) = self.b.size_hint();
+
+ // Compute a * b_orig + b for both lower and upper bound
+ size_hint::add(
+ size_hint::mul(self.a.size_hint(), self.b_orig.size_hint()),
+ (b_min * has_cur, b_max.map(move |x| x * has_cur)))
+ }
+
+ fn fold<Acc, G>(mut self, mut accum: Acc, mut f: G) -> Acc
+ where G: FnMut(Acc, Self::Item) -> Acc,
+ {
+ // use a split loop to handle the loose a_cur as well as avoiding to
+ // clone b_orig at the end.
+ if let Some(mut a) = self.a_cur.take() {
+ let mut b = self.b;
+ loop {
+ accum = b.fold(accum, |acc, elt| f(acc, (a.clone(), elt)));
+
+ // we can only continue iterating a if we had a first element;
+ if let Some(next_a) = self.a.next() {
+ b = self.b_orig.clone();
+ a = next_a;
+ } else {
+ break;
+ }
+ }
+ }
+ accum
+ }
+}
+
+impl<I, J> FusedIterator for Product<I, J>
+ where I: FusedIterator,
+ J: Clone + FusedIterator,
+ I::Item: Clone
+{}
+
+/// A “meta iterator adaptor”. Its closure receives a reference to the iterator
+/// and may pick off as many elements as it likes, to produce the next iterator element.
+///
+/// Iterator element type is *X*, if the return type of `F` is *Option\<X\>*.
+///
+/// See [`.batching()`](crate::Itertools::batching) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Batching<I, F> {
+ f: F,
+ iter: I,
+}
+
+impl<I, F> fmt::Debug for Batching<I, F> where I: fmt::Debug {
+ debug_fmt_fields!(Batching, iter);
+}
+
+/// Create a new Batching iterator.
+pub fn batching<I, F>(iter: I, f: F) -> Batching<I, F> {
+ Batching { f, iter }
+}
+
+impl<B, F, I> Iterator for Batching<I, F>
+ where I: Iterator,
+ F: FnMut(&mut I) -> Option<B>
+{
+ type Item = B;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ (self.f)(&mut self.iter)
+ }
+}
+
+/// An iterator adaptor that steps a number elements in the base iterator
+/// for each iteration.
+///
+/// The iterator steps by yielding the next element from the base iterator,
+/// then skipping forward *n-1* elements.
+///
+/// See [`.step()`](crate::Itertools::step) for more information.
+#[deprecated(note="Use std .step_by() instead", since="0.8.0")]
+#[allow(deprecated)]
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Step<I> {
+ iter: Fuse<I>,
+ skip: usize,
+}
+
+/// Create a `Step` iterator.
+///
+/// **Panics** if the step is 0.
+#[allow(deprecated)]
+pub fn step<I>(iter: I, step: usize) -> Step<I>
+ where I: Iterator
+{
+ assert!(step != 0);
+ Step {
+ iter: iter.fuse(),
+ skip: step - 1,
+ }
+}
+
+#[allow(deprecated)]
+impl<I> Iterator for Step<I>
+ where I: Iterator
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ let elt = self.iter.next();
+ if self.skip > 0 {
+ self.iter.nth(self.skip - 1);
+ }
+ elt
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (low, high) = self.iter.size_hint();
+ let div = |x: usize| {
+ if x == 0 {
+ 0
+ } else {
+ 1 + (x - 1) / (self.skip + 1)
+ }
+ };
+ (div(low), high.map(div))
+ }
+}
+
+// known size
+#[allow(deprecated)]
+impl<I> ExactSizeIterator for Step<I>
+ where I: ExactSizeIterator
+{}
+
+pub trait MergePredicate<T> {
+ fn merge_pred(&mut self, a: &T, b: &T) -> bool;
+}
+
+#[derive(Clone, Debug)]
+pub struct MergeLte;
+
+impl<T: PartialOrd> MergePredicate<T> for MergeLte {
+ fn merge_pred(&mut self, a: &T, b: &T) -> bool {
+ a <= b
+ }
+}
+
+/// An iterator adaptor that merges the two base iterators in ascending order.
+/// If both base iterators are sorted (ascending), the result is sorted.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.merge()`](crate::Itertools::merge_by) for more information.
+pub type Merge<I, J> = MergeBy<I, J, MergeLte>;
+
+/// Create an iterator that merges elements in `i` and `j`.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::merge`](crate::Itertools::merge).
+///
+/// ```
+/// use itertools::merge;
+///
+/// for elt in merge(&[1, 2, 3], &[2, 3, 4]) {
+/// /* loop body */
+/// }
+/// ```
+pub fn merge<I, J>(i: I, j: J) -> Merge<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
+ where I: IntoIterator,
+ J: IntoIterator<Item = I::Item>,
+ I::Item: PartialOrd
+{
+ merge_by_new(i, j, MergeLte)
+}
+
+/// An iterator adaptor that merges the two base iterators in ascending order.
+/// If both base iterators are sorted (ascending), the result is sorted.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.merge_by()`](crate::Itertools::merge_by) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct MergeBy<I, J, F>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>
+{
+ a: Peekable<I>,
+ b: Peekable<J>,
+ fused: Option<bool>,
+ cmp: F,
+}
+
+impl<I, J, F> fmt::Debug for MergeBy<I, J, F>
+ where I: Iterator + fmt::Debug, J: Iterator<Item = I::Item> + fmt::Debug,
+ I::Item: fmt::Debug,
+{
+ debug_fmt_fields!(MergeBy, a, b);
+}
+
+impl<T, F: FnMut(&T, &T)->bool> MergePredicate<T> for F {
+ fn merge_pred(&mut self, a: &T, b: &T) -> bool {
+ self(a, b)
+ }
+}
+
+/// Create a `MergeBy` iterator.
+pub fn merge_by_new<I, J, F>(a: I, b: J, cmp: F) -> MergeBy<I::IntoIter, J::IntoIter, F>
+ where I: IntoIterator,
+ J: IntoIterator<Item = I::Item>,
+ F: MergePredicate<I::Item>,
+{
+ MergeBy {
+ a: a.into_iter().peekable(),
+ b: b.into_iter().peekable(),
+ fused: None,
+ cmp,
+ }
+}
+
+impl<I, J, F> Clone for MergeBy<I, J, F>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>,
+ Peekable<I>: Clone,
+ Peekable<J>: Clone,
+ F: Clone
+{
+ clone_fields!(a, b, fused, cmp);
+}
+
+impl<I, J, F> Iterator for MergeBy<I, J, F>
+ where I: Iterator,
+ J: Iterator<Item = I::Item>,
+ F: MergePredicate<I::Item>
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let less_than = match self.fused {
+ Some(lt) => lt,
+ None => match (self.a.peek(), self.b.peek()) {
+ (Some(a), Some(b)) => self.cmp.merge_pred(a, b),
+ (Some(_), None) => {
+ self.fused = Some(true);
+ true
+ }
+ (None, Some(_)) => {
+ self.fused = Some(false);
+ false
+ }
+ (None, None) => return None,
+ }
+ };
+ if less_than {
+ self.a.next()
+ } else {
+ self.b.next()
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // Not ExactSizeIterator because size may be larger than usize
+ size_hint::add(self.a.size_hint(), self.b.size_hint())
+ }
+}
+
+impl<I, J, F> FusedIterator for MergeBy<I, J, F>
+ where I: FusedIterator,
+ J: FusedIterator<Item = I::Item>,
+ F: MergePredicate<I::Item>
+{}
+
+/// An iterator adaptor that borrows from a `Clone`-able iterator
+/// to only pick off elements while the predicate returns `true`.
+///
+/// See [`.take_while_ref()`](crate::Itertools::take_while_ref) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct TakeWhileRef<'a, I: 'a, F> {
+ iter: &'a mut I,
+ f: F,
+}
+
+impl<'a, I, F> fmt::Debug for TakeWhileRef<'a, I, F>
+ where I: Iterator + fmt::Debug,
+{
+ debug_fmt_fields!(TakeWhileRef, iter);
+}
+
+/// Create a new `TakeWhileRef` from a reference to clonable iterator.
+pub fn take_while_ref<I, F>(iter: &mut I, f: F) -> TakeWhileRef<I, F>
+ where I: Iterator + Clone
+{
+ TakeWhileRef { iter, f }
+}
+
+impl<'a, I, F> Iterator for TakeWhileRef<'a, I, F>
+ where I: Iterator + Clone,
+ F: FnMut(&I::Item) -> bool
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let old = self.iter.clone();
+ match self.iter.next() {
+ None => None,
+ Some(elt) => {
+ if (self.f)(&elt) {
+ Some(elt)
+ } else {
+ *self.iter = old;
+ None
+ }
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+}
+
+/// An iterator adaptor that filters `Option<A>` iterator elements
+/// and produces `A`. Stops on the first `None` encountered.
+///
+/// See [`.while_some()`](crate::Itertools::while_some) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct WhileSome<I> {
+ iter: I,
+}
+
+/// Create a new `WhileSome<I>`.
+pub fn while_some<I>(iter: I) -> WhileSome<I> {
+ WhileSome { iter }
+}
+
+impl<I, A> Iterator for WhileSome<I>
+ where I: Iterator<Item = Option<A>>
+{
+ type Item = A;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.iter.next() {
+ None | Some(None) => None,
+ Some(elt) => elt,
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+}
+
+/// An iterator to iterate through all combinations in a `Clone`-able iterator that produces tuples
+/// of a specific size.
+///
+/// See [`.tuple_combinations()`](crate::Itertools::tuple_combinations) for more
+/// information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct TupleCombinations<I, T>
+ where I: Iterator,
+ T: HasCombination<I>
+{
+ iter: T::Combination,
+ _mi: PhantomData<I>,
+}
+
+pub trait HasCombination<I>: Sized {
+ type Combination: From<I> + Iterator<Item = Self>;
+}
+
+/// Create a new `TupleCombinations` from a clonable iterator.
+pub fn tuple_combinations<T, I>(iter: I) -> TupleCombinations<I, T>
+ where I: Iterator + Clone,
+ I::Item: Clone,
+ T: HasCombination<I>,
+{
+ TupleCombinations {
+ iter: T::Combination::from(iter),
+ _mi: PhantomData,
+ }
+}
+
+impl<I, T> Iterator for TupleCombinations<I, T>
+ where I: Iterator,
+ T: HasCombination<I>,
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.next()
+ }
+}
+
+impl<I, T> FusedIterator for TupleCombinations<I, T>
+ where I: FusedIterator,
+ T: HasCombination<I>,
+{}
+
+#[derive(Clone, Debug)]
+pub struct Tuple1Combination<I> {
+ iter: I,
+}
+
+impl<I> From<I> for Tuple1Combination<I> {
+ fn from(iter: I) -> Self {
+ Tuple1Combination { iter }
+ }
+}
+
+impl<I: Iterator> Iterator for Tuple1Combination<I> {
+ type Item = (I::Item,);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.next().map(|x| (x,))
+ }
+}
+
+impl<I: Iterator> HasCombination<I> for (I::Item,) {
+ type Combination = Tuple1Combination<I>;
+}
+
+macro_rules! impl_tuple_combination {
+ ($C:ident $P:ident ; $($X:ident)*) => (
+ #[derive(Clone, Debug)]
+ pub struct $C<I: Iterator> {
+ item: Option<I::Item>,
+ iter: I,
+ c: $P<I>,
+ }
+
+ impl<I: Iterator + Clone> From<I> for $C<I> {
+ fn from(mut iter: I) -> Self {
+ Self {
+ item: iter.next(),
+ iter: iter.clone(),
+ c: iter.into(),
+ }
+ }
+ }
+
+ impl<I: Iterator + Clone> From<I> for $C<Fuse<I>> {
+ fn from(iter: I) -> Self {
+ Self::from(iter.fuse())
+ }
+ }
+
+ impl<I, A> Iterator for $C<I>
+ where I: Iterator<Item = A> + Clone,
+ I::Item: Clone
+ {
+ type Item = (A, $(ignore_ident!($X, A)),*);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if let Some(($($X),*,)) = self.c.next() {
+ let z = self.item.clone().unwrap();
+ Some((z, $($X),*))
+ } else {
+ self.item = self.iter.next();
+ self.item.clone().and_then(|z| {
+ self.c = self.iter.clone().into();
+ self.c.next().map(|($($X),*,)| (z, $($X),*))
+ })
+ }
+ }
+ }
+
+ impl<I, A> HasCombination<I> for (A, $(ignore_ident!($X, A)),*)
+ where I: Iterator<Item = A> + Clone,
+ I::Item: Clone
+ {
+ type Combination = $C<Fuse<I>>;
+ }
+ )
+}
+
+// This snippet generates the twelve `impl_tuple_combination!` invocations:
+// use core::iter;
+// use itertools::Itertools;
+//
+// for i in 2..=12 {
+// println!("impl_tuple_combination!(Tuple{arity}Combination Tuple{prev}Combination; {idents});",
+// arity = i,
+// prev = i - 1,
+// idents = ('a'..'z').take(i - 1).join(" "),
+// );
+// }
+// It could probably be replaced by a bit more macro cleverness.
+impl_tuple_combination!(Tuple2Combination Tuple1Combination; a);
+impl_tuple_combination!(Tuple3Combination Tuple2Combination; a b);
+impl_tuple_combination!(Tuple4Combination Tuple3Combination; a b c);
+impl_tuple_combination!(Tuple5Combination Tuple4Combination; a b c d);
+impl_tuple_combination!(Tuple6Combination Tuple5Combination; a b c d e);
+impl_tuple_combination!(Tuple7Combination Tuple6Combination; a b c d e f);
+impl_tuple_combination!(Tuple8Combination Tuple7Combination; a b c d e f g);
+impl_tuple_combination!(Tuple9Combination Tuple8Combination; a b c d e f g h);
+impl_tuple_combination!(Tuple10Combination Tuple9Combination; a b c d e f g h i);
+impl_tuple_combination!(Tuple11Combination Tuple10Combination; a b c d e f g h i j);
+impl_tuple_combination!(Tuple12Combination Tuple11Combination; a b c d e f g h i j k);
+
+/// An iterator adapter to filter values within a nested `Result::Ok`.
+///
+/// See [`.filter_ok()`](crate::Itertools::filter_ok) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct FilterOk<I, F> {
+ iter: I,
+ f: F
+}
+
+impl<I, F> fmt::Debug for FilterOk<I, F>
+where
+ I: fmt::Debug,
+{
+ debug_fmt_fields!(FilterOk, iter);
+}
+
+/// Create a new `FilterOk` iterator.
+pub fn filter_ok<I, F, T, E>(iter: I, f: F) -> FilterOk<I, F>
+ where I: Iterator<Item = Result<T, E>>,
+ F: FnMut(&T) -> bool,
+{
+ FilterOk {
+ iter,
+ f,
+ }
+}
+
+impl<I, F, T, E> Iterator for FilterOk<I, F>
+ where I: Iterator<Item = Result<T, E>>,
+ F: FnMut(&T) -> bool,
+{
+ type Item = Result<T, E>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ loop {
+ match self.iter.next() {
+ Some(Ok(v)) => {
+ if (self.f)(&v) {
+ return Some(Ok(v));
+ }
+ },
+ Some(Err(e)) => return Some(Err(e)),
+ None => return None,
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+
+ fn fold<Acc, Fold>(self, init: Acc, fold_f: Fold) -> Acc
+ where Fold: FnMut(Acc, Self::Item) -> Acc,
+ {
+ let mut f = self.f;
+ self.iter.filter(|v| {
+ v.as_ref().map(&mut f).unwrap_or(true)
+ }).fold(init, fold_f)
+ }
+
+ fn collect<C>(self) -> C
+ where C: FromIterator<Self::Item>
+ {
+ let mut f = self.f;
+ self.iter.filter(|v| {
+ v.as_ref().map(&mut f).unwrap_or(true)
+ }).collect()
+ }
+}
+
+impl<I, F, T, E> FusedIterator for FilterOk<I, F>
+ where I: FusedIterator<Item = Result<T, E>>,
+ F: FnMut(&T) -> bool,
+{}
+
+/// An iterator adapter to filter and apply a transformation on values within a nested `Result::Ok`.
+///
+/// See [`.filter_map_ok()`](crate::Itertools::filter_map_ok) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct FilterMapOk<I, F> {
+ iter: I,
+ f: F
+}
+
+impl<I, F> fmt::Debug for FilterMapOk<I, F>
+where
+ I: fmt::Debug,
+{
+ debug_fmt_fields!(FilterMapOk, iter);
+}
+
+fn transpose_result<T, E>(result: Result<Option<T>, E>) -> Option<Result<T, E>> {
+ match result {
+ Ok(Some(v)) => Some(Ok(v)),
+ Ok(None) => None,
+ Err(e) => Some(Err(e)),
+ }
+}
+
+/// Create a new `FilterOk` iterator.
+pub fn filter_map_ok<I, F, T, U, E>(iter: I, f: F) -> FilterMapOk<I, F>
+ where I: Iterator<Item = Result<T, E>>,
+ F: FnMut(T) -> Option<U>,
+{
+ FilterMapOk {
+ iter,
+ f,
+ }
+}
+
+impl<I, F, T, U, E> Iterator for FilterMapOk<I, F>
+ where I: Iterator<Item = Result<T, E>>,
+ F: FnMut(T) -> Option<U>,
+{
+ type Item = Result<U, E>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ loop {
+ match self.iter.next() {
+ Some(Ok(v)) => {
+ if let Some(v) = (self.f)(v) {
+ return Some(Ok(v));
+ }
+ },
+ Some(Err(e)) => return Some(Err(e)),
+ None => return None,
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+
+ fn fold<Acc, Fold>(self, init: Acc, fold_f: Fold) -> Acc
+ where Fold: FnMut(Acc, Self::Item) -> Acc,
+ {
+ let mut f = self.f;
+ self.iter.filter_map(|v| {
+ transpose_result(v.map(&mut f))
+ }).fold(init, fold_f)
+ }
+
+ fn collect<C>(self) -> C
+ where C: FromIterator<Self::Item>
+ {
+ let mut f = self.f;
+ self.iter.filter_map(|v| {
+ transpose_result(v.map(&mut f))
+ }).collect()
+ }
+}
+
+impl<I, F, T, U, E> FusedIterator for FilterMapOk<I, F>
+ where I: FusedIterator<Item = Result<T, E>>,
+ F: FnMut(T) -> Option<U>,
+{}
+
+/// An iterator adapter to get the positions of each element that matches a predicate.
+///
+/// See [`.positions()`](crate::Itertools::positions) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Positions<I, F> {
+ iter: I,
+ f: F,
+ count: usize,
+}
+
+impl<I, F> fmt::Debug for Positions<I, F>
+where
+ I: fmt::Debug,
+{
+ debug_fmt_fields!(Positions, iter, count);
+}
+
+/// Create a new `Positions` iterator.
+pub fn positions<I, F>(iter: I, f: F) -> Positions<I, F>
+ where I: Iterator,
+ F: FnMut(I::Item) -> bool,
+{
+ Positions {
+ iter,
+ f,
+ count: 0
+ }
+}
+
+impl<I, F> Iterator for Positions<I, F>
+ where I: Iterator,
+ F: FnMut(I::Item) -> bool,
+{
+ type Item = usize;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.next() {
+ let i = self.count;
+ self.count = i + 1;
+ if (self.f)(v) {
+ return Some(i);
+ }
+ }
+ None
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+}
+
+impl<I, F> DoubleEndedIterator for Positions<I, F>
+ where I: DoubleEndedIterator + ExactSizeIterator,
+ F: FnMut(I::Item) -> bool,
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.next_back() {
+ if (self.f)(v) {
+ return Some(self.count + self.iter.len())
+ }
+ }
+ None
+ }
+}
+
+impl<I, F> FusedIterator for Positions<I, F>
+ where I: FusedIterator,
+ F: FnMut(I::Item) -> bool,
+{}
+
+/// An iterator adapter to apply a mutating function to each element before yielding it.
+///
+/// See [`.update()`](crate::Itertools::update) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Update<I, F> {
+ iter: I,
+ f: F,
+}
+
+impl<I, F> fmt::Debug for Update<I, F>
+where
+ I: fmt::Debug,
+{
+ debug_fmt_fields!(Update, iter);
+}
+
+/// Create a new `Update` iterator.
+pub fn update<I, F>(iter: I, f: F) -> Update<I, F>
+where
+ I: Iterator,
+ F: FnMut(&mut I::Item),
+{
+ Update { iter, f }
+}
+
+impl<I, F> Iterator for Update<I, F>
+where
+ I: Iterator,
+ F: FnMut(&mut I::Item),
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if let Some(mut v) = self.iter.next() {
+ (self.f)(&mut v);
+ Some(v)
+ } else {
+ None
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+
+ fn fold<Acc, G>(self, init: Acc, mut g: G) -> Acc
+ where G: FnMut(Acc, Self::Item) -> Acc,
+ {
+ let mut f = self.f;
+ self.iter.fold(init, move |acc, mut v| { f(&mut v); g(acc, v) })
+ }
+
+ // if possible, re-use inner iterator specializations in collect
+ fn collect<C>(self) -> C
+ where C: FromIterator<Self::Item>
+ {
+ let mut f = self.f;
+ self.iter.map(move |mut v| { f(&mut v); v }).collect()
+ }
+}
+
+impl<I, F> ExactSizeIterator for Update<I, F>
+where
+ I: ExactSizeIterator,
+ F: FnMut(&mut I::Item),
+{}
+
+impl<I, F> DoubleEndedIterator for Update<I, F>
+where
+ I: DoubleEndedIterator,
+ F: FnMut(&mut I::Item),
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ if let Some(mut v) = self.iter.next_back() {
+ (self.f)(&mut v);
+ Some(v)
+ } else {
+ None
+ }
+ }
+}
+
+impl<I, F> FusedIterator for Update<I, F>
+where
+ I: FusedIterator,
+ F: FnMut(&mut I::Item),
+{}
--- /dev/null
+#![cfg(feature = "use_alloc")]
+
+use crate::size_hint;
+use crate::Itertools;
+
+use alloc::vec::Vec;
+
+#[derive(Clone)]
+/// An iterator adaptor that iterates over the cartesian product of
+/// multiple iterators of type `I`.
+///
+/// An iterator element type is `Vec<I>`.
+///
+/// See [`.multi_cartesian_product()`](crate::Itertools::multi_cartesian_product)
+/// for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct MultiProduct<I>(Vec<MultiProductIter<I>>)
+ where I: Iterator + Clone,
+ I::Item: Clone;
+
+impl<I> std::fmt::Debug for MultiProduct<I>
+where
+ I: Iterator + Clone + std::fmt::Debug,
+ I::Item: Clone + std::fmt::Debug,
+{
+ debug_fmt_fields!(CoalesceBy, 0);
+}
+
+/// Create a new cartesian product iterator over an arbitrary number
+/// of iterators of the same type.
+///
+/// Iterator element is of type `Vec<H::Item::Item>`.
+pub fn multi_cartesian_product<H>(iters: H) -> MultiProduct<<H::Item as IntoIterator>::IntoIter>
+ where H: Iterator,
+ H::Item: IntoIterator,
+ <H::Item as IntoIterator>::IntoIter: Clone,
+ <H::Item as IntoIterator>::Item: Clone
+{
+ MultiProduct(iters.map(|i| MultiProductIter::new(i.into_iter())).collect())
+}
+
+#[derive(Clone, Debug)]
+/// Holds the state of a single iterator within a `MultiProduct`.
+struct MultiProductIter<I>
+ where I: Iterator + Clone,
+ I::Item: Clone
+{
+ cur: Option<I::Item>,
+ iter: I,
+ iter_orig: I,
+}
+
+/// Holds the current state during an iteration of a `MultiProduct`.
+#[derive(Debug)]
+enum MultiProductIterState {
+ StartOfIter,
+ MidIter { on_first_iter: bool },
+}
+
+impl<I> MultiProduct<I>
+ where I: Iterator + Clone,
+ I::Item: Clone
+{
+ /// Iterates the rightmost iterator, then recursively iterates iterators
+ /// to the left if necessary.
+ ///
+ /// Returns true if the iteration succeeded, else false.
+ fn iterate_last(
+ multi_iters: &mut [MultiProductIter<I>],
+ mut state: MultiProductIterState
+ ) -> bool {
+ use self::MultiProductIterState::*;
+
+ if let Some((last, rest)) = multi_iters.split_last_mut() {
+ let on_first_iter = match state {
+ StartOfIter => {
+ let on_first_iter = !last.in_progress();
+ state = MidIter { on_first_iter };
+ on_first_iter
+ },
+ MidIter { on_first_iter } => on_first_iter
+ };
+
+ if !on_first_iter {
+ last.iterate();
+ }
+
+ if last.in_progress() {
+ true
+ } else if MultiProduct::iterate_last(rest, state) {
+ last.reset();
+ last.iterate();
+ // If iterator is None twice consecutively, then iterator is
+ // empty; whole product is empty.
+ last.in_progress()
+ } else {
+ false
+ }
+ } else {
+ // Reached end of iterator list. On initialisation, return true.
+ // At end of iteration (final iterator finishes), finish.
+ match state {
+ StartOfIter => false,
+ MidIter { on_first_iter } => on_first_iter
+ }
+ }
+ }
+
+ /// Returns the unwrapped value of the next iteration.
+ fn curr_iterator(&self) -> Vec<I::Item> {
+ self.0.iter().map(|multi_iter| {
+ multi_iter.cur.clone().unwrap()
+ }).collect()
+ }
+
+ /// Returns true if iteration has started and has not yet finished; false
+ /// otherwise.
+ fn in_progress(&self) -> bool {
+ if let Some(last) = self.0.last() {
+ last.in_progress()
+ } else {
+ false
+ }
+ }
+}
+
+impl<I> MultiProductIter<I>
+ where I: Iterator + Clone,
+ I::Item: Clone
+{
+ fn new(iter: I) -> Self {
+ MultiProductIter {
+ cur: None,
+ iter: iter.clone(),
+ iter_orig: iter
+ }
+ }
+
+ /// Iterate the managed iterator.
+ fn iterate(&mut self) {
+ self.cur = self.iter.next();
+ }
+
+ /// Reset the managed iterator.
+ fn reset(&mut self) {
+ self.iter = self.iter_orig.clone();
+ }
+
+ /// Returns true if the current iterator has been started and has not yet
+ /// finished; false otherwise.
+ fn in_progress(&self) -> bool {
+ self.cur.is_some()
+ }
+}
+
+impl<I> Iterator for MultiProduct<I>
+ where I: Iterator + Clone,
+ I::Item: Clone
+{
+ type Item = Vec<I::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if MultiProduct::iterate_last(
+ &mut self.0,
+ MultiProductIterState::StartOfIter
+ ) {
+ Some(self.curr_iterator())
+ } else {
+ None
+ }
+ }
+
+ fn count(self) -> usize {
+ if self.0.is_empty() {
+ return 0;
+ }
+
+ if !self.in_progress() {
+ return self.0.into_iter().fold(1, |acc, multi_iter| {
+ acc * multi_iter.iter.count()
+ });
+ }
+
+ self.0.into_iter().fold(
+ 0,
+ |acc, MultiProductIter { iter, iter_orig, cur: _ }| {
+ let total_count = iter_orig.count();
+ let cur_count = iter.count();
+ acc * total_count + cur_count
+ }
+ )
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // Not ExactSizeIterator because size may be larger than usize
+ if self.0.is_empty() {
+ return (0, Some(0));
+ }
+
+ if !self.in_progress() {
+ return self.0.iter().fold((1, Some(1)), |acc, multi_iter| {
+ size_hint::mul(acc, multi_iter.iter.size_hint())
+ });
+ }
+
+ self.0.iter().fold(
+ (0, Some(0)),
+ |acc, &MultiProductIter { ref iter, ref iter_orig, cur: _ }| {
+ let cur_size = iter.size_hint();
+ let total_size = iter_orig.size_hint();
+ size_hint::add(size_hint::mul(acc, total_size), cur_size)
+ }
+ )
+ }
+
+ fn last(self) -> Option<Self::Item> {
+ let iter_count = self.0.len();
+
+ let lasts: Self::Item = self.0.into_iter()
+ .map(|multi_iter| multi_iter.iter.last())
+ .while_some()
+ .collect();
+
+ if lasts.len() == iter_count {
+ Some(lasts)
+ } else {
+ None
+ }
+ }
+}
--- /dev/null
+use std::fmt;
+use std::iter::FusedIterator;
+
+use super::lazy_buffer::LazyBuffer;
+use alloc::vec::Vec;
+
+/// An iterator to iterate through all the `k`-length combinations in an iterator.
+///
+/// See [`.combinations()`](crate::Itertools::combinations) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Combinations<I: Iterator> {
+ indices: Vec<usize>,
+ pool: LazyBuffer<I>,
+ first: bool,
+}
+
+impl<I> Clone for Combinations<I>
+ where I: Clone + Iterator,
+ I::Item: Clone,
+{
+ clone_fields!(indices, pool, first);
+}
+
+impl<I> fmt::Debug for Combinations<I>
+ where I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug,
+{
+ debug_fmt_fields!(Combinations, indices, pool, first);
+}
+
+/// Create a new `Combinations` from a clonable iterator.
+pub fn combinations<I>(iter: I, k: usize) -> Combinations<I>
+ where I: Iterator
+{
+ let mut pool = LazyBuffer::new(iter);
+ pool.prefill(k);
+
+ Combinations {
+ indices: (0..k).collect(),
+ pool,
+ first: true,
+ }
+}
+
+impl<I: Iterator> Combinations<I> {
+ /// Returns the length of a combination produced by this iterator.
+ #[inline]
+ pub fn k(&self) -> usize { self.indices.len() }
+
+ /// Returns the (current) length of the pool from which combination elements are
+ /// selected. This value can change between invocations of [`next`](Combinations::next).
+ #[inline]
+ pub fn n(&self) -> usize { self.pool.len() }
+
+ /// Returns a reference to the source iterator.
+ #[inline]
+ pub(crate) fn src(&self) -> &I { &self.pool.it }
+
+ /// Resets this `Combinations` back to an initial state for combinations of length
+ /// `k` over the same pool data source. If `k` is larger than the current length
+ /// of the data pool an attempt is made to prefill the pool so that it holds `k`
+ /// elements.
+ pub(crate) fn reset(&mut self, k: usize) {
+ self.first = true;
+
+ if k < self.indices.len() {
+ self.indices.truncate(k);
+ for i in 0..k {
+ self.indices[i] = i;
+ }
+
+ } else {
+ for i in 0..self.indices.len() {
+ self.indices[i] = i;
+ }
+ self.indices.extend(self.indices.len()..k);
+ self.pool.prefill(k);
+ }
+ }
+}
+
+impl<I> Iterator for Combinations<I>
+ where I: Iterator,
+ I::Item: Clone
+{
+ type Item = Vec<I::Item>;
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.first {
+ if self.k() > self.n() {
+ return None;
+ }
+ self.first = false;
+ } else if self.indices.is_empty() {
+ return None;
+ } else {
+ // Scan from the end, looking for an index to increment
+ let mut i: usize = self.indices.len() - 1;
+
+ // Check if we need to consume more from the iterator
+ if self.indices[i] == self.pool.len() - 1 {
+ self.pool.get_next(); // may change pool size
+ }
+
+ while self.indices[i] == i + self.pool.len() - self.indices.len() {
+ if i > 0 {
+ i -= 1;
+ } else {
+ // Reached the last combination
+ return None;
+ }
+ }
+
+ // Increment index, and reset the ones to its right
+ self.indices[i] += 1;
+ for j in i+1..self.indices.len() {
+ self.indices[j] = self.indices[j - 1] + 1;
+ }
+ }
+
+ // Create result vector based on the indices
+ Some(self.indices.iter().map(|i| self.pool[*i].clone()).collect())
+ }
+}
+
+impl<I> FusedIterator for Combinations<I>
+ where I: Iterator,
+ I::Item: Clone
+{}
--- /dev/null
+use alloc::vec::Vec;
+use std::fmt;
+use std::iter::FusedIterator;
+
+use super::lazy_buffer::LazyBuffer;
+
+/// An iterator to iterate through all the `n`-length combinations in an iterator, with replacement.
+///
+/// See [`.combinations_with_replacement()`](crate::Itertools::combinations_with_replacement)
+/// for more information.
+#[derive(Clone)]
+pub struct CombinationsWithReplacement<I>
+where
+ I: Iterator,
+ I::Item: Clone,
+{
+ indices: Vec<usize>,
+ pool: LazyBuffer<I>,
+ first: bool,
+}
+
+impl<I> fmt::Debug for CombinationsWithReplacement<I>
+where
+ I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug + Clone,
+{
+ debug_fmt_fields!(Combinations, indices, pool, first);
+}
+
+impl<I> CombinationsWithReplacement<I>
+where
+ I: Iterator,
+ I::Item: Clone,
+{
+ /// Map the current mask over the pool to get an output combination
+ fn current(&self) -> Vec<I::Item> {
+ self.indices.iter().map(|i| self.pool[*i].clone()).collect()
+ }
+}
+
+/// Create a new `CombinationsWithReplacement` from a clonable iterator.
+pub fn combinations_with_replacement<I>(iter: I, k: usize) -> CombinationsWithReplacement<I>
+where
+ I: Iterator,
+ I::Item: Clone,
+{
+ let indices: Vec<usize> = alloc::vec![0; k];
+ let pool: LazyBuffer<I> = LazyBuffer::new(iter);
+
+ CombinationsWithReplacement {
+ indices,
+ pool,
+ first: true,
+ }
+}
+
+impl<I> Iterator for CombinationsWithReplacement<I>
+where
+ I: Iterator,
+ I::Item: Clone,
+{
+ type Item = Vec<I::Item>;
+ fn next(&mut self) -> Option<Self::Item> {
+ // If this is the first iteration, return early
+ if self.first {
+ // In empty edge cases, stop iterating immediately
+ return if !(self.indices.is_empty() || self.pool.get_next()) {
+ None
+ // Otherwise, yield the initial state
+ } else {
+ self.first = false;
+ Some(self.current())
+ };
+ }
+
+ // Check if we need to consume more from the iterator
+ // This will run while we increment our first index digit
+ self.pool.get_next();
+
+ // Work out where we need to update our indices
+ let mut increment: Option<(usize, usize)> = None;
+ for (i, indices_int) in self.indices.iter().enumerate().rev() {
+ if *indices_int < self.pool.len()-1 {
+ increment = Some((i, indices_int + 1));
+ break;
+ }
+ }
+
+ match increment {
+ // If we can update the indices further
+ Some((increment_from, increment_value)) => {
+ // We need to update the rightmost non-max value
+ // and all those to the right
+ for indices_index in increment_from..self.indices.len() {
+ self.indices[indices_index] = increment_value;
+ }
+ Some(self.current())
+ }
+ // Otherwise, we're done
+ None => None,
+ }
+ }
+}
+
+impl<I> FusedIterator for CombinationsWithReplacement<I>
+where
+ I: Iterator,
+ I::Item: Clone,
+{}
--- /dev/null
+use crate::Itertools;
+
+/// Combine all an iterator's elements into one element by using [`Extend`].
+///
+/// [`IntoIterator`]-enabled version of [`Itertools::concat`].
+///
+/// This combinator will extend the first item with each of the rest of the
+/// items of the iterator. If the iterator is empty, the default value of
+/// `I::Item` is returned.
+///
+/// ```rust
+/// use itertools::concat;
+///
+/// let input = vec![vec![1], vec![2, 3], vec![4, 5, 6]];
+/// assert_eq!(concat(input), vec![1, 2, 3, 4, 5, 6]);
+/// ```
+pub fn concat<I>(iterable: I) -> I::Item
+ where I: IntoIterator,
+ I::Item: Extend<<<I as IntoIterator>::Item as IntoIterator>::Item> + IntoIterator + Default
+{
+ #[allow(deprecated)] //TODO: once msrv hits 1.51. replace `fold1` with `reduce`
+ iterable.into_iter().fold1(|mut a, b| { a.extend(b); a }).unwrap_or_default()
+}
--- /dev/null
+
+macro_rules! impl_cons_iter(
+ ($_A:ident, $_B:ident, ) => (); // stop
+
+ ($A:ident, $($B:ident,)*) => (
+ impl_cons_iter!($($B,)*);
+ #[allow(non_snake_case)]
+ impl<X, Iter, $($B),*> Iterator for ConsTuples<Iter, (($($B,)*), X)>
+ where Iter: Iterator<Item = (($($B,)*), X)>,
+ {
+ type Item = ($($B,)* X, );
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, ))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.iter.size_hint()
+ }
+ fn fold<Acc, Fold>(self, accum: Acc, mut f: Fold) -> Acc
+ where Fold: FnMut(Acc, Self::Item) -> Acc,
+ {
+ self.iter.fold(accum, move |acc, (($($B,)*), x)| f(acc, ($($B,)* x, )))
+ }
+ }
+
+ #[allow(non_snake_case)]
+ impl<X, Iter, $($B),*> DoubleEndedIterator for ConsTuples<Iter, (($($B,)*), X)>
+ where Iter: DoubleEndedIterator<Item = (($($B,)*), X)>,
+ {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, ))
+ }
+ }
+
+ );
+);
+
+impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,);
+
+/// An iterator that maps an iterator of tuples like
+/// `((A, B), C)` to an iterator of `(A, B, C)`.
+///
+/// Used by the `iproduct!()` macro.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug)]
+pub struct ConsTuples<I, J>
+ where I: Iterator<Item=J>,
+{
+ iter: I,
+}
+
+impl<I, J> Clone for ConsTuples<I, J>
+ where I: Clone + Iterator<Item=J>,
+{
+ clone_fields!(iter);
+}
+
+/// Create an iterator that maps for example iterators of
+/// `((A, B), C)` to `(A, B, C)`.
+pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I::IntoIter, J>
+ where I: IntoIterator<Item=J>
+{
+ ConsTuples { iter: iterable.into_iter() }
+}
--- /dev/null
+//! "Diff"ing iterators for caching elements to sequential collections without requiring the new
+//! elements' iterator to be `Clone`.
+//!
+//! - [`Diff`] (produced by the [`diff_with`] function)
+//! describes the difference between two non-`Clone` iterators `I` and `J` after breaking ASAP from
+//! a lock-step comparison.
+
+use crate::free::put_back;
+use crate::structs::PutBack;
+
+/// A type returned by the [`diff_with`] function.
+///
+/// `Diff` represents the way in which the elements yielded by the iterator `I` differ to some
+/// iterator `J`.
+pub enum Diff<I, J>
+ where I: Iterator,
+ J: Iterator
+{
+ /// The index of the first non-matching element along with both iterator's remaining elements
+ /// starting with the first mis-match.
+ FirstMismatch(usize, PutBack<I>, PutBack<J>),
+ /// The total number of elements that were in `J` along with the remaining elements of `I`.
+ Shorter(usize, PutBack<I>),
+ /// The total number of elements that were in `I` along with the remaining elements of `J`.
+ Longer(usize, PutBack<J>),
+}
+
+/// Compares every element yielded by both `i` and `j` with the given function in lock-step and
+/// returns a [`Diff`] which describes how `j` differs from `i`.
+///
+/// If the number of elements yielded by `j` is less than the number of elements yielded by `i`,
+/// the number of `j` elements yielded will be returned along with `i`'s remaining elements as
+/// `Diff::Shorter`.
+///
+/// If the two elements of a step differ, the index of those elements along with the remaining
+/// elements of both `i` and `j` are returned as `Diff::FirstMismatch`.
+///
+/// If `i` becomes exhausted before `j` becomes exhausted, the number of elements in `i` along with
+/// the remaining `j` elements will be returned as `Diff::Longer`.
+pub fn diff_with<I, J, F>(i: I, j: J, is_equal: F)
+ -> Option<Diff<I::IntoIter, J::IntoIter>>
+ where I: IntoIterator,
+ J: IntoIterator,
+ F: Fn(&I::Item, &J::Item) -> bool
+{
+ let mut i = i.into_iter();
+ let mut j = j.into_iter();
+ let mut idx = 0;
+ while let Some(i_elem) = i.next() {
+ match j.next() {
+ None => return Some(Diff::Shorter(idx, put_back(i).with_value(i_elem))),
+ Some(j_elem) => if !is_equal(&i_elem, &j_elem) {
+ let remaining_i = put_back(i).with_value(i_elem);
+ let remaining_j = put_back(j).with_value(j_elem);
+ return Some(Diff::FirstMismatch(idx, remaining_i, remaining_j));
+ },
+ }
+ idx += 1;
+ }
+ j.next().map(|j_elem| Diff::Longer(idx, put_back(j).with_value(j_elem)))
+}
--- /dev/null
+use std::hash::Hash;
+
+mod private {
+ use std::collections::HashMap;
+ use std::hash::Hash;
+ use std::fmt;
+
+ #[derive(Clone)]
+ #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+ pub struct DuplicatesBy<I: Iterator, Key, F> {
+ pub(crate) iter: I,
+ pub(crate) meta: Meta<Key, F>,
+ }
+
+ impl<I, V, F> fmt::Debug for DuplicatesBy<I, V, F>
+ where
+ I: Iterator + fmt::Debug,
+ V: fmt::Debug + Hash + Eq,
+ {
+ debug_fmt_fields!(DuplicatesBy, iter, meta.used);
+ }
+
+ impl<I: Iterator, Key: Eq + Hash, F> DuplicatesBy<I, Key, F> {
+ pub(crate) fn new(iter: I, key_method: F) -> Self {
+ DuplicatesBy {
+ iter,
+ meta: Meta {
+ used: HashMap::new(),
+ pending: 0,
+ key_method,
+ },
+ }
+ }
+ }
+
+ #[derive(Clone)]
+ pub struct Meta<Key, F> {
+ used: HashMap<Key, bool>,
+ pending: usize,
+ key_method: F,
+ }
+
+ impl<Key, F> Meta<Key, F>
+ where
+ Key: Eq + Hash,
+ {
+ /// Takes an item and returns it back to the caller if it's the second time we see it.
+ /// Otherwise the item is consumed and None is returned
+ #[inline(always)]
+ fn filter<I>(&mut self, item: I) -> Option<I>
+ where
+ F: KeyMethod<Key, I>,
+ {
+ let kv = self.key_method.make(item);
+ match self.used.get_mut(kv.key_ref()) {
+ None => {
+ self.used.insert(kv.key(), false);
+ self.pending += 1;
+ None
+ }
+ Some(true) => None,
+ Some(produced) => {
+ *produced = true;
+ self.pending -= 1;
+ Some(kv.value())
+ }
+ }
+ }
+ }
+
+ impl<I, Key, F> Iterator for DuplicatesBy<I, Key, F>
+ where
+ I: Iterator,
+ Key: Eq + Hash,
+ F: KeyMethod<Key, I::Item>,
+ {
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let DuplicatesBy { iter, meta } = self;
+ iter.find_map(|v| meta.filter(v))
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (_, hi) = self.iter.size_hint();
+ let hi = hi.map(|hi| {
+ if hi <= self.meta.pending {
+ // fewer or equally many iter-remaining elements than pending elements
+ // => at most, each iter-remaining element is matched
+ hi
+ } else {
+ // fewer pending elements than iter-remaining elements
+ // => at most:
+ // * each pending element is matched
+ // * the other iter-remaining elements come in pairs
+ self.meta.pending + (hi - self.meta.pending) / 2
+ }
+ });
+ // The lower bound is always 0 since we might only get unique items from now on
+ (0, hi)
+ }
+ }
+
+ impl<I, Key, F> DoubleEndedIterator for DuplicatesBy<I, Key, F>
+ where
+ I: DoubleEndedIterator,
+ Key: Eq + Hash,
+ F: KeyMethod<Key, I::Item>,
+ {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ let DuplicatesBy { iter, meta } = self;
+ iter.rev().find_map(|v| meta.filter(v))
+ }
+ }
+
+ /// A keying method for use with `DuplicatesBy`
+ pub trait KeyMethod<K, V> {
+ type Container: KeyXorValue<K, V>;
+
+ fn make(&mut self, value: V) -> Self::Container;
+ }
+
+ /// Apply the identity function to elements before checking them for equality.
+ #[derive(Debug)]
+ pub struct ById;
+ impl<V> KeyMethod<V, V> for ById {
+ type Container = JustValue<V>;
+
+ fn make(&mut self, v: V) -> Self::Container {
+ JustValue(v)
+ }
+ }
+
+ /// Apply a user-supplied function to elements before checking them for equality.
+ pub struct ByFn<F>(pub(crate) F);
+ impl<F> fmt::Debug for ByFn<F> {
+ debug_fmt_fields!(ByFn,);
+ }
+ impl<K, V, F> KeyMethod<K, V> for ByFn<F>
+ where
+ F: FnMut(&V) -> K,
+ {
+ type Container = KeyValue<K, V>;
+
+ fn make(&mut self, v: V) -> Self::Container {
+ KeyValue((self.0)(&v), v)
+ }
+ }
+
+ // Implementors of this trait can hold onto a key and a value but only give access to one of them
+ // at a time. This allows the key and the value to be the same value internally
+ pub trait KeyXorValue<K, V> {
+ fn key_ref(&self) -> &K;
+ fn key(self) -> K;
+ fn value(self) -> V;
+ }
+
+ #[derive(Debug)]
+ pub struct KeyValue<K, V>(K, V);
+ impl<K, V> KeyXorValue<K, V> for KeyValue<K, V> {
+ fn key_ref(&self) -> &K {
+ &self.0
+ }
+ fn key(self) -> K {
+ self.0
+ }
+ fn value(self) -> V {
+ self.1
+ }
+ }
+
+ #[derive(Debug)]
+ pub struct JustValue<V>(V);
+ impl<V> KeyXorValue<V, V> for JustValue<V> {
+ fn key_ref(&self) -> &V {
+ &self.0
+ }
+ fn key(self) -> V {
+ self.0
+ }
+ fn value(self) -> V {
+ self.0
+ }
+ }
+}
+
+/// An iterator adapter to filter for duplicate elements.
+///
+/// See [`.duplicates_by()`](crate::Itertools::duplicates_by) for more information.
+pub type DuplicatesBy<I, V, F> = private::DuplicatesBy<I, V, private::ByFn<F>>;
+
+/// Create a new `DuplicatesBy` iterator.
+pub fn duplicates_by<I, Key, F>(iter: I, f: F) -> DuplicatesBy<I, Key, F>
+where
+ Key: Eq + Hash,
+ F: FnMut(&I::Item) -> Key,
+ I: Iterator,
+{
+ DuplicatesBy::new(iter, private::ByFn(f))
+}
+
+/// An iterator adapter to filter out duplicate elements.
+///
+/// See [`.duplicates()`](crate::Itertools::duplicates) for more information.
+pub type Duplicates<I> = private::DuplicatesBy<I, <I as Iterator>::Item, private::ById>;
+
+/// Create a new `Duplicates` iterator.
+pub fn duplicates<I>(iter: I) -> Duplicates<I>
+where
+ I: Iterator,
+ I::Item: Eq + Hash,
+{
+ Duplicates::new(iter, private::ById)
+}
+
--- /dev/null
+use crate::EitherOrBoth::*;
+
+use either::Either;
+
+/// Value that either holds a single A or B, or both.
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
+pub enum EitherOrBoth<A, B> {
+ /// Both values are present.
+ Both(A, B),
+ /// Only the left value of type `A` is present.
+ Left(A),
+ /// Only the right value of type `B` is present.
+ Right(B),
+}
+
+impl<A, B> EitherOrBoth<A, B> {
+ /// If `Left`, or `Both`, return true, otherwise, return false.
+ pub fn has_left(&self) -> bool {
+ self.as_ref().left().is_some()
+ }
+
+ /// If `Right`, or `Both`, return true, otherwise, return false.
+ pub fn has_right(&self) -> bool {
+ self.as_ref().right().is_some()
+ }
+
+ /// If Left, return true otherwise, return false.
+ /// Exclusive version of [`has_left`](EitherOrBoth::has_left).
+ pub fn is_left(&self) -> bool {
+ match *self {
+ Left(_) => true,
+ _ => false,
+ }
+ }
+
+ /// If Right, return true otherwise, return false.
+ /// Exclusive version of [`has_right`](EitherOrBoth::has_right).
+ pub fn is_right(&self) -> bool {
+ match *self {
+ Right(_) => true,
+ _ => false,
+ }
+ }
+
+ /// If Right, return true otherwise, return false.
+ /// Equivalent to `self.as_ref().both().is_some()`.
+ pub fn is_both(&self) -> bool {
+ self.as_ref().both().is_some()
+ }
+
+ /// If `Left`, or `Both`, return `Some` with the left value, otherwise, return `None`.
+ pub fn left(self) -> Option<A> {
+ match self {
+ Left(left) | Both(left, _) => Some(left),
+ _ => None,
+ }
+ }
+
+ /// If `Right`, or `Both`, return `Some` with the right value, otherwise, return `None`.
+ pub fn right(self) -> Option<B> {
+ match self {
+ Right(right) | Both(_, right) => Some(right),
+ _ => None,
+ }
+ }
+
+ /// If Both, return `Some` tuple containing left and right.
+ pub fn both(self) -> Option<(A, B)> {
+ match self {
+ Both(a, b) => Some((a, b)),
+ _ => None,
+ }
+ }
+
+ /// Converts from `&EitherOrBoth<A, B>` to `EitherOrBoth<&A, &B>`.
+ pub fn as_ref(&self) -> EitherOrBoth<&A, &B> {
+ match *self {
+ Left(ref left) => Left(left),
+ Right(ref right) => Right(right),
+ Both(ref left, ref right) => Both(left, right),
+ }
+ }
+
+ /// Converts from `&mut EitherOrBoth<A, B>` to `EitherOrBoth<&mut A, &mut B>`.
+ pub fn as_mut(&mut self) -> EitherOrBoth<&mut A, &mut B> {
+ match *self {
+ Left(ref mut left) => Left(left),
+ Right(ref mut right) => Right(right),
+ Both(ref mut left, ref mut right) => Both(left, right),
+ }
+ }
+
+ /// Convert `EitherOrBoth<A, B>` to `EitherOrBoth<B, A>`.
+ pub fn flip(self) -> EitherOrBoth<B, A> {
+ match self {
+ Left(a) => Right(a),
+ Right(b) => Left(b),
+ Both(a, b) => Both(b, a),
+ }
+ }
+
+ /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, b)` variants. If it is
+ /// present rewrapping the result in `self`'s original variant.
+ pub fn map_left<F, M>(self, f: F) -> EitherOrBoth<M, B>
+ where
+ F: FnOnce(A) -> M,
+ {
+ match self {
+ Both(a, b) => Both(f(a), b),
+ Left(a) => Left(f(a)),
+ Right(b) => Right(b),
+ }
+ }
+
+ /// Apply the function `f` on the value `b` in `Right(b)` or `Both(a, b)` variants.
+ /// If it is present rewrapping the result in `self`'s original variant.
+ pub fn map_right<F, M>(self, f: F) -> EitherOrBoth<A, M>
+ where
+ F: FnOnce(B) -> M,
+ {
+ match self {
+ Left(a) => Left(a),
+ Right(b) => Right(f(b)),
+ Both(a, b) => Both(a, f(b)),
+ }
+ }
+
+ /// Apply the functions `f` and `g` on the value `a` and `b` respectively;
+ /// found in `Left(a)`, `Right(b)`, or `Both(a, b)` variants.
+ /// The Result is rewrapped `self`'s original variant.
+ pub fn map_any<F, L, G, R>(self, f: F, g: G) -> EitherOrBoth<L, R>
+ where
+ F: FnOnce(A) -> L,
+ G: FnOnce(B) -> R,
+ {
+ match self {
+ Left(a) => Left(f(a)),
+ Right(b) => Right(g(b)),
+ Both(a, b) => Both(f(a), g(b)),
+ }
+ }
+
+ /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, _)` variants if it is
+ /// present.
+ pub fn left_and_then<F, L>(self, f: F) -> EitherOrBoth<L, B>
+ where
+ F: FnOnce(A) -> EitherOrBoth<L, B>,
+ {
+ match self {
+ Left(a) | Both(a, _) => f(a),
+ Right(b) => Right(b),
+ }
+ }
+
+ /// Apply the function `f` on the value `b`
+ /// in `Right(b)` or `Both(_, b)` variants if it is present.
+ pub fn right_and_then<F, R>(self, f: F) -> EitherOrBoth<A, R>
+ where
+ F: FnOnce(B) -> EitherOrBoth<A, R>,
+ {
+ match self {
+ Left(a) => Left(a),
+ Right(b) | Both(_, b) => f(b),
+ }
+ }
+
+ /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present.
+ /// Otherwise, returns the wrapped value for the present element, and the supplied
+ /// value for the other. The first (`l`) argument is used for a missing `Left`
+ /// value. The second (`r`) argument is used for a missing `Right` value.
+ ///
+ /// Arguments passed to `or` are eagerly evaluated; if you are passing
+ /// the result of a function call, it is recommended to use [`or_else`],
+ /// which is lazily evaluated.
+ ///
+ /// [`or_else`]: EitherOrBoth::or_else
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # use itertools::EitherOrBoth;
+ /// assert_eq!(EitherOrBoth::Both("tree", 1).or("stone", 5), ("tree", 1));
+ /// assert_eq!(EitherOrBoth::Left("tree").or("stone", 5), ("tree", 5));
+ /// assert_eq!(EitherOrBoth::Right(1).or("stone", 5), ("stone", 1));
+ /// ```
+ pub fn or(self, l: A, r: B) -> (A, B) {
+ match self {
+ Left(inner_l) => (inner_l, r),
+ Right(inner_r) => (l, inner_r),
+ Both(inner_l, inner_r) => (inner_l, inner_r),
+ }
+ }
+
+ /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present.
+ /// Otherwise, returns the wrapped value for the present element, and the [`default`](Default::default)
+ /// for the other.
+ pub fn or_default(self) -> (A, B)
+ where
+ A: Default,
+ B: Default,
+ {
+ match self {
+ EitherOrBoth::Left(l) => (l, B::default()),
+ EitherOrBoth::Right(r) => (A::default(), r),
+ EitherOrBoth::Both(l, r) => (l, r),
+ }
+ }
+
+ /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present.
+ /// Otherwise, returns the wrapped value for the present element, and computes the
+ /// missing value with the supplied closure. The first argument (`l`) is used for a
+ /// missing `Left` value. The second argument (`r`) is used for a missing `Right` value.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # use itertools::EitherOrBoth;
+ /// let k = 10;
+ /// assert_eq!(EitherOrBoth::Both("tree", 1).or_else(|| "stone", || 2 * k), ("tree", 1));
+ /// assert_eq!(EitherOrBoth::Left("tree").or_else(|| "stone", || 2 * k), ("tree", 20));
+ /// assert_eq!(EitherOrBoth::Right(1).or_else(|| "stone", || 2 * k), ("stone", 1));
+ /// ```
+ pub fn or_else<L: FnOnce() -> A, R: FnOnce() -> B>(self, l: L, r: R) -> (A, B) {
+ match self {
+ Left(inner_l) => (inner_l, r()),
+ Right(inner_r) => (l(), inner_r),
+ Both(inner_l, inner_r) => (inner_l, inner_r),
+ }
+ }
+}
+
+impl<T> EitherOrBoth<T, T> {
+ /// Return either value of left, right, or the product of `f` applied where `Both` are present.
+ pub fn reduce<F>(self, f: F) -> T
+ where
+ F: FnOnce(T, T) -> T,
+ {
+ match self {
+ Left(a) => a,
+ Right(b) => b,
+ Both(a, b) => f(a, b),
+ }
+ }
+}
+
+impl<A, B> Into<Option<Either<A, B>>> for EitherOrBoth<A, B> {
+ fn into(self) -> Option<Either<A, B>> {
+ match self {
+ EitherOrBoth::Left(l) => Some(Either::Left(l)),
+ EitherOrBoth::Right(r) => Some(Either::Right(r)),
+ _ => None,
+ }
+ }
+}
--- /dev/null
+#[cfg(feature = "use_std")]
+use std::error::Error;
+use std::fmt::{Debug, Display, Formatter, Result as FmtResult};
+
+use std::iter::ExactSizeIterator;
+
+use either::Either;
+
+use crate::size_hint;
+
+/// Iterator returned for the error case of `IterTools::exactly_one()`
+/// This iterator yields exactly the same elements as the input iterator.
+///
+/// During the execution of `exactly_one` the iterator must be mutated. This wrapper
+/// effectively "restores" the state of the input iterator when it's handed back.
+///
+/// This is very similar to `PutBackN` except this iterator only supports 0-2 elements and does not
+/// use a `Vec`.
+#[derive(Clone)]
+pub struct ExactlyOneError<I>
+where
+ I: Iterator,
+{
+ first_two: Option<Either<[I::Item; 2], I::Item>>,
+ inner: I,
+}
+
+impl<I> ExactlyOneError<I>
+where
+ I: Iterator,
+{
+ /// Creates a new `ExactlyOneErr` iterator.
+ pub(crate) fn new(first_two: Option<Either<[I::Item; 2], I::Item>>, inner: I) -> Self {
+ Self { first_two, inner }
+ }
+
+ fn additional_len(&self) -> usize {
+ match self.first_two {
+ Some(Either::Left(_)) => 2,
+ Some(Either::Right(_)) => 1,
+ None => 0,
+ }
+ }
+}
+
+impl<I> Iterator for ExactlyOneError<I>
+where
+ I: Iterator,
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.first_two.take() {
+ Some(Either::Left([first, second])) => {
+ self.first_two = Some(Either::Right(second));
+ Some(first)
+ },
+ Some(Either::Right(second)) => {
+ Some(second)
+ }
+ None => {
+ self.inner.next()
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add_scalar(self.inner.size_hint(), self.additional_len())
+ }
+}
+
+
+impl<I> ExactSizeIterator for ExactlyOneError<I> where I: ExactSizeIterator {}
+
+impl<I> Display for ExactlyOneError<I>
+ where I: Iterator,
+{
+ fn fmt(&self, f: &mut Formatter) -> FmtResult {
+ let additional = self.additional_len();
+ if additional > 0 {
+ write!(f, "got at least 2 elements when exactly one was expected")
+ } else {
+ write!(f, "got zero elements when exactly one was expected")
+ }
+ }
+}
+
+impl<I> Debug for ExactlyOneError<I>
+ where I: Iterator + Debug,
+ I::Item: Debug,
+{
+ fn fmt(&self, f: &mut Formatter) -> FmtResult {
+ match &self.first_two {
+ Some(Either::Left([first, second])) => {
+ write!(f, "ExactlyOneError[First: {:?}, Second: {:?}, RemainingIter: {:?}]", first, second, self.inner)
+ },
+ Some(Either::Right(second)) => {
+ write!(f, "ExactlyOneError[Second: {:?}, RemainingIter: {:?}]", second, self.inner)
+ }
+ None => {
+ write!(f, "ExactlyOneError[RemainingIter: {:?}]", self.inner)
+ }
+ }
+ }
+}
+
+#[cfg(feature = "use_std")]
+impl<I> Error for ExactlyOneError<I> where I: Iterator + Debug, I::Item: Debug, {}
+
+
--- /dev/null
+use std::cmp::Ordering;
+
+/// Implementation guts for `min_set`, `min_set_by`, and `min_set_by_key`.
+pub fn min_set_impl<I, K, F, Compare>(
+ mut it: I,
+ mut key_for: F,
+ mut compare: Compare,
+) -> Vec<I::Item>
+where
+ I: Iterator,
+ F: FnMut(&I::Item) -> K,
+ Compare: FnMut(&I::Item, &I::Item, &K, &K) -> Ordering,
+{
+ match it.next() {
+ None => Vec::new(),
+ Some(element) => {
+ let mut current_key = key_for(&element);
+ let mut result = vec![element];
+ it.for_each(|element| {
+ let key = key_for(&element);
+ match compare(&element, &result[0], &key, ¤t_key) {
+ Ordering::Less => {
+ result.clear();
+ result.push(element);
+ current_key = key;
+ }
+ Ordering::Equal => {
+ result.push(element);
+ }
+ Ordering::Greater => {}
+ }
+ });
+ result
+ }
+ }
+}
+
+/// Implementation guts for `ax_set`, `max_set_by`, and `max_set_by_key`.
+pub fn max_set_impl<I, K, F, Compare>(it: I, key_for: F, mut compare: Compare) -> Vec<I::Item>
+where
+ I: Iterator,
+ F: FnMut(&I::Item) -> K,
+ Compare: FnMut(&I::Item, &I::Item, &K, &K) -> Ordering,
+{
+ min_set_impl(it, key_for, |it1, it2, key1, key2| {
+ compare(it2, it1, key2, key1)
+ })
+}
--- /dev/null
+use crate::size_hint;
+use std::{
+ fmt,
+ iter::{DoubleEndedIterator, FusedIterator},
+};
+
+pub fn flatten_ok<I, T, E>(iter: I) -> FlattenOk<I, T, E>
+where
+ I: Iterator<Item = Result<T, E>>,
+ T: IntoIterator,
+{
+ FlattenOk {
+ iter,
+ inner_front: None,
+ inner_back: None,
+ }
+}
+
+/// An iterator adaptor that flattens `Result::Ok` values and
+/// allows `Result::Err` values through unchanged.
+///
+/// See [`.flatten_ok()`](crate::Itertools::flatten_ok) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct FlattenOk<I, T, E>
+where
+ I: Iterator<Item = Result<T, E>>,
+ T: IntoIterator,
+{
+ iter: I,
+ inner_front: Option<T::IntoIter>,
+ inner_back: Option<T::IntoIter>,
+}
+
+impl<I, T, E> Iterator for FlattenOk<I, T, E>
+where
+ I: Iterator<Item = Result<T, E>>,
+ T: IntoIterator,
+{
+ type Item = Result<T::Item, E>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ loop {
+ // Handle the front inner iterator.
+ if let Some(inner) = &mut self.inner_front {
+ if let Some(item) = inner.next() {
+ return Some(Ok(item));
+ }
+
+ // This is necessary for the iterator to implement `FusedIterator`
+ // with only the original iterator being fused.
+ self.inner_front = None;
+ }
+
+ match self.iter.next() {
+ Some(Ok(ok)) => self.inner_front = Some(ok.into_iter()),
+ Some(Err(e)) => return Some(Err(e)),
+ None => {
+ // Handle the back inner iterator.
+ if let Some(inner) = &mut self.inner_back {
+ if let Some(item) = inner.next() {
+ return Some(Ok(item));
+ }
+
+ // This is necessary for the iterator to implement `FusedIterator`
+ // with only the original iterator being fused.
+ self.inner_back = None;
+ } else {
+ return None;
+ }
+ }
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let inner_hint = |inner: &Option<T::IntoIter>| {
+ inner
+ .as_ref()
+ .map(Iterator::size_hint)
+ .unwrap_or((0, Some(0)))
+ };
+ let inner_front = inner_hint(&self.inner_front);
+ let inner_back = inner_hint(&self.inner_back);
+ // The outer iterator `Ok` case could be (0, None) as we don't know its size_hint yet.
+ let outer = match self.iter.size_hint() {
+ (0, Some(0)) => (0, Some(0)),
+ _ => (0, None),
+ };
+
+ size_hint::add(size_hint::add(inner_front, inner_back), outer)
+ }
+}
+
+impl<I, T, E> DoubleEndedIterator for FlattenOk<I, T, E>
+where
+ I: DoubleEndedIterator<Item = Result<T, E>>,
+ T: IntoIterator,
+ T::IntoIter: DoubleEndedIterator,
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ loop {
+ // Handle the back inner iterator.
+ if let Some(inner) = &mut self.inner_back {
+ if let Some(item) = inner.next_back() {
+ return Some(Ok(item));
+ }
+
+ // This is necessary for the iterator to implement `FusedIterator`
+ // with only the original iterator being fused.
+ self.inner_back = None;
+ }
+
+ match self.iter.next_back() {
+ Some(Ok(ok)) => self.inner_back = Some(ok.into_iter()),
+ Some(Err(e)) => return Some(Err(e)),
+ None => {
+ // Handle the front inner iterator.
+ if let Some(inner) = &mut self.inner_front {
+ if let Some(item) = inner.next_back() {
+ return Some(Ok(item));
+ }
+
+ // This is necessary for the iterator to implement `FusedIterator`
+ // with only the original iterator being fused.
+ self.inner_front = None;
+ } else {
+ return None;
+ }
+ }
+ }
+ }
+ }
+}
+
+impl<I, T, E> Clone for FlattenOk<I, T, E>
+where
+ I: Iterator<Item = Result<T, E>> + Clone,
+ T: IntoIterator,
+ T::IntoIter: Clone,
+{
+ clone_fields!(iter, inner_front, inner_back);
+}
+
+impl<I, T, E> fmt::Debug for FlattenOk<I, T, E>
+where
+ I: Iterator<Item = Result<T, E>> + fmt::Debug,
+ T: IntoIterator,
+ T::IntoIter: fmt::Debug,
+{
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_struct("FlattenOk")
+ .field("iter", &self.iter)
+ .field("inner_front", &self.inner_front)
+ .field("inner_back", &self.inner_back)
+ .finish()
+ }
+}
+
+/// Only the iterator being flattened needs to implement [`FusedIterator`].
+impl<I, T, E> FusedIterator for FlattenOk<I, T, E>
+where
+ I: FusedIterator<Item = Result<T, E>>,
+ T: IntoIterator,
+{
+}
--- /dev/null
+use std::fmt;
+use std::cell::RefCell;
+
+/// Format all iterator elements lazily, separated by `sep`.
+///
+/// The format value can only be formatted once, after that the iterator is
+/// exhausted.
+///
+/// See [`.format_with()`](crate::Itertools::format_with) for more information.
+#[derive(Clone)]
+pub struct FormatWith<'a, I, F> {
+ sep: &'a str,
+ /// FormatWith uses interior mutability because Display::fmt takes &self.
+ inner: RefCell<Option<(I, F)>>,
+}
+
+/// Format all iterator elements lazily, separated by `sep`.
+///
+/// The format value can only be formatted once, after that the iterator is
+/// exhausted.
+///
+/// See [`.format()`](crate::Itertools::format)
+/// for more information.
+#[derive(Clone)]
+pub struct Format<'a, I> {
+ sep: &'a str,
+ /// Format uses interior mutability because Display::fmt takes &self.
+ inner: RefCell<Option<I>>,
+}
+
+pub fn new_format<I, F>(iter: I, separator: &str, f: F) -> FormatWith<'_, I, F>
+ where I: Iterator,
+ F: FnMut(I::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result
+{
+ FormatWith {
+ sep: separator,
+ inner: RefCell::new(Some((iter, f))),
+ }
+}
+
+pub fn new_format_default<I>(iter: I, separator: &str) -> Format<'_, I>
+ where I: Iterator,
+{
+ Format {
+ sep: separator,
+ inner: RefCell::new(Some(iter)),
+ }
+}
+
+impl<'a, I, F> fmt::Display for FormatWith<'a, I, F>
+ where I: Iterator,
+ F: FnMut(I::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result
+{
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ let (mut iter, mut format) = match self.inner.borrow_mut().take() {
+ Some(t) => t,
+ None => panic!("FormatWith: was already formatted once"),
+ };
+
+ if let Some(fst) = iter.next() {
+ format(fst, &mut |disp: &dyn fmt::Display| disp.fmt(f))?;
+ iter.try_for_each(|elt| {
+ if !self.sep.is_empty() {
+ f.write_str(self.sep)?;
+ }
+ format(elt, &mut |disp: &dyn fmt::Display| disp.fmt(f))
+ })?;
+ }
+ Ok(())
+ }
+}
+
+impl<'a, I> Format<'a, I>
+ where I: Iterator,
+{
+ fn format<F>(&self, f: &mut fmt::Formatter, mut cb: F) -> fmt::Result
+ where F: FnMut(&I::Item, &mut fmt::Formatter) -> fmt::Result,
+ {
+ let mut iter = match self.inner.borrow_mut().take() {
+ Some(t) => t,
+ None => panic!("Format: was already formatted once"),
+ };
+
+ if let Some(fst) = iter.next() {
+ cb(&fst, f)?;
+ iter.try_for_each(|elt| {
+ if !self.sep.is_empty() {
+ f.write_str(self.sep)?;
+ }
+ cb(&elt, f)
+ })?;
+ }
+ Ok(())
+ }
+}
+
+macro_rules! impl_format {
+ ($($fmt_trait:ident)*) => {
+ $(
+ impl<'a, I> fmt::$fmt_trait for Format<'a, I>
+ where I: Iterator,
+ I::Item: fmt::$fmt_trait,
+ {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ self.format(f, fmt::$fmt_trait::fmt)
+ }
+ }
+ )*
+ }
+}
+
+impl_format!{Display Debug
+ UpperExp LowerExp UpperHex LowerHex Octal Binary Pointer}
--- /dev/null
+//! Free functions that create iterator adaptors or call iterator methods.
+//!
+//! The benefit of free functions is that they accept any [`IntoIterator`] as
+//! argument, so the resulting code may be easier to read.
+
+#[cfg(feature = "use_alloc")]
+use std::fmt::Display;
+use std::iter::{self, Zip};
+#[cfg(feature = "use_alloc")]
+type VecIntoIter<T> = alloc::vec::IntoIter<T>;
+
+#[cfg(feature = "use_alloc")]
+use alloc::{
+ string::String,
+};
+
+use crate::Itertools;
+use crate::intersperse::{Intersperse, IntersperseWith};
+
+pub use crate::adaptors::{
+ interleave,
+ merge,
+ put_back,
+};
+#[cfg(feature = "use_alloc")]
+pub use crate::put_back_n_impl::put_back_n;
+#[cfg(feature = "use_alloc")]
+pub use crate::multipeek_impl::multipeek;
+#[cfg(feature = "use_alloc")]
+pub use crate::peek_nth::peek_nth;
+#[cfg(feature = "use_alloc")]
+pub use crate::kmerge_impl::kmerge;
+pub use crate::zip_eq_impl::zip_eq;
+pub use crate::merge_join::merge_join_by;
+#[cfg(feature = "use_alloc")]
+pub use crate::rciter_impl::rciter;
+
+/// Iterate `iterable` with a particular value inserted between each element.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::intersperse`].
+///
+/// ```
+/// use itertools::intersperse;
+///
+/// itertools::assert_equal(intersperse((0..3), 8), vec![0, 8, 1, 8, 2]);
+/// ```
+pub fn intersperse<I>(iterable: I, element: I::Item) -> Intersperse<I::IntoIter>
+ where I: IntoIterator,
+ <I as IntoIterator>::Item: Clone
+{
+ Itertools::intersperse(iterable.into_iter(), element)
+}
+
+/// Iterate `iterable` with a particular value created by a function inserted
+/// between each element.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::intersperse_with`].
+///
+/// ```
+/// use itertools::intersperse_with;
+///
+/// let mut i = 10;
+/// itertools::assert_equal(intersperse_with((0..3), || { i -= 1; i }), vec![0, 9, 1, 8, 2]);
+/// assert_eq!(i, 8);
+/// ```
+pub fn intersperse_with<I, F>(iterable: I, element: F) -> IntersperseWith<I::IntoIter, F>
+ where I: IntoIterator,
+ F: FnMut() -> I::Item
+{
+ Itertools::intersperse_with(iterable.into_iter(), element)
+}
+
+/// Iterate `iterable` with a running index.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::enumerate`].
+///
+/// ```
+/// use itertools::enumerate;
+///
+/// for (i, elt) in enumerate(&[1, 2, 3]) {
+/// /* loop body */
+/// }
+/// ```
+pub fn enumerate<I>(iterable: I) -> iter::Enumerate<I::IntoIter>
+ where I: IntoIterator
+{
+ iterable.into_iter().enumerate()
+}
+
+/// Iterate `iterable` in reverse.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::rev`].
+///
+/// ```
+/// use itertools::rev;
+///
+/// for elt in rev(&[1, 2, 3]) {
+/// /* loop body */
+/// }
+/// ```
+pub fn rev<I>(iterable: I) -> iter::Rev<I::IntoIter>
+ where I: IntoIterator,
+ I::IntoIter: DoubleEndedIterator
+{
+ iterable.into_iter().rev()
+}
+
+/// Converts the arguments to iterators and zips them.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::zip`].
+///
+/// ## Example
+///
+/// ```
+/// use itertools::zip;
+///
+/// let mut result: Vec<(i32, char)> = Vec::new();
+///
+/// for (a, b) in zip(&[1, 2, 3, 4, 5], &['a', 'b', 'c']) {
+/// result.push((*a, *b));
+/// }
+/// assert_eq!(result, vec![(1, 'a'),(2, 'b'),(3, 'c')]);
+/// ```
+#[deprecated(note="Use [std::iter::zip](https://doc.rust-lang.org/std/iter/fn.zip.html) instead", since="0.10.4")]
+pub fn zip<I, J>(i: I, j: J) -> Zip<I::IntoIter, J::IntoIter>
+ where I: IntoIterator,
+ J: IntoIterator
+{
+ i.into_iter().zip(j)
+}
+
+
+/// Takes two iterables and creates a new iterator over both in sequence.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::chain`].
+///
+/// ## Example
+/// ```
+/// use itertools::chain;
+///
+/// let mut result:Vec<i32> = Vec::new();
+///
+/// for element in chain(&[1, 2, 3], &[4]) {
+/// result.push(*element);
+/// }
+/// assert_eq!(result, vec![1, 2, 3, 4]);
+/// ```
+pub fn chain<I, J>(i: I, j: J) -> iter::Chain<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
+ where I: IntoIterator,
+ J: IntoIterator<Item = I::Item>
+{
+ i.into_iter().chain(j)
+}
+
+/// Create an iterator that clones each element from &T to T
+///
+/// [`IntoIterator`] enabled version of [`Iterator::cloned`].
+///
+/// ```
+/// use itertools::cloned;
+///
+/// assert_eq!(cloned(b"abc").next(), Some(b'a'));
+/// ```
+pub fn cloned<'a, I, T: 'a>(iterable: I) -> iter::Cloned<I::IntoIter>
+ where I: IntoIterator<Item=&'a T>,
+ T: Clone,
+{
+ iterable.into_iter().cloned()
+}
+
+/// Perform a fold operation over the iterable.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::fold`].
+///
+/// ```
+/// use itertools::fold;
+///
+/// assert_eq!(fold(&[1., 2., 3.], 0., |a, &b| f32::max(a, b)), 3.);
+/// ```
+pub fn fold<I, B, F>(iterable: I, init: B, f: F) -> B
+ where I: IntoIterator,
+ F: FnMut(B, I::Item) -> B
+{
+ iterable.into_iter().fold(init, f)
+}
+
+/// Test whether the predicate holds for all elements in the iterable.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::all`].
+///
+/// ```
+/// use itertools::all;
+///
+/// assert!(all(&[1, 2, 3], |elt| *elt > 0));
+/// ```
+pub fn all<I, F>(iterable: I, f: F) -> bool
+ where I: IntoIterator,
+ F: FnMut(I::Item) -> bool
+{
+ iterable.into_iter().all(f)
+}
+
+/// Test whether the predicate holds for any elements in the iterable.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::any`].
+///
+/// ```
+/// use itertools::any;
+///
+/// assert!(any(&[0, -1, 2], |elt| *elt > 0));
+/// ```
+pub fn any<I, F>(iterable: I, f: F) -> bool
+ where I: IntoIterator,
+ F: FnMut(I::Item) -> bool
+{
+ iterable.into_iter().any(f)
+}
+
+/// Return the maximum value of the iterable.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::max`].
+///
+/// ```
+/// use itertools::max;
+///
+/// assert_eq!(max(0..10), Some(9));
+/// ```
+pub fn max<I>(iterable: I) -> Option<I::Item>
+ where I: IntoIterator,
+ I::Item: Ord
+{
+ iterable.into_iter().max()
+}
+
+/// Return the minimum value of the iterable.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::min`].
+///
+/// ```
+/// use itertools::min;
+///
+/// assert_eq!(min(0..10), Some(0));
+/// ```
+pub fn min<I>(iterable: I) -> Option<I::Item>
+ where I: IntoIterator,
+ I::Item: Ord
+{
+ iterable.into_iter().min()
+}
+
+
+/// Combine all iterator elements into one String, separated by `sep`.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::join`].
+///
+/// ```
+/// use itertools::join;
+///
+/// assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3");
+/// ```
+#[cfg(feature = "use_alloc")]
+pub fn join<I>(iterable: I, sep: &str) -> String
+ where I: IntoIterator,
+ I::Item: Display
+{
+ iterable.into_iter().join(sep)
+}
+
+/// Sort all iterator elements into a new iterator in ascending order.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::sorted`].
+///
+/// ```
+/// use itertools::sorted;
+/// use itertools::assert_equal;
+///
+/// assert_equal(sorted("rust".chars()), "rstu".chars());
+/// ```
+#[cfg(feature = "use_alloc")]
+pub fn sorted<I>(iterable: I) -> VecIntoIter<I::Item>
+ where I: IntoIterator,
+ I::Item: Ord
+{
+ iterable.into_iter().sorted()
+}
+
--- /dev/null
+#![cfg(feature = "use_std")]
+
+use std::collections::HashMap;
+use std::hash::Hash;
+use std::iter::Iterator;
+
+/// Return a `HashMap` of keys mapped to a list of their corresponding values.
+///
+/// See [`.into_group_map()`](crate::Itertools::into_group_map)
+/// for more information.
+pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
+ where I: Iterator<Item=(K, V)>,
+ K: Hash + Eq,
+{
+ let mut lookup = HashMap::new();
+
+ iter.for_each(|(key, val)| {
+ lookup.entry(key).or_insert_with(Vec::new).push(val);
+ });
+
+ lookup
+}
+
+pub fn into_group_map_by<I, K, V>(iter: I, f: impl Fn(&V) -> K) -> HashMap<K, Vec<V>>
+ where
+ I: Iterator<Item=V>,
+ K: Hash + Eq,
+{
+ into_group_map(
+ iter.map(|v| (f(&v), v))
+ )
+}
--- /dev/null
+use std::cell::{Cell, RefCell};
+use alloc::vec::{self, Vec};
+
+/// A trait to unify `FnMut` for `GroupBy` with the chunk key in `IntoChunks`
+trait KeyFunction<A> {
+ type Key;
+ fn call_mut(&mut self, arg: A) -> Self::Key;
+}
+
+impl<A, K, F: ?Sized> KeyFunction<A> for F
+ where F: FnMut(A) -> K
+{
+ type Key = K;
+ #[inline]
+ fn call_mut(&mut self, arg: A) -> Self::Key {
+ (*self)(arg)
+ }
+}
+
+
+/// `ChunkIndex` acts like the grouping key function for `IntoChunks`
+#[derive(Debug)]
+struct ChunkIndex {
+ size: usize,
+ index: usize,
+ key: usize,
+}
+
+impl ChunkIndex {
+ #[inline(always)]
+ fn new(size: usize) -> Self {
+ ChunkIndex {
+ size,
+ index: 0,
+ key: 0,
+ }
+ }
+}
+
+impl<A> KeyFunction<A> for ChunkIndex {
+ type Key = usize;
+ #[inline(always)]
+ fn call_mut(&mut self, _arg: A) -> Self::Key {
+ if self.index == self.size {
+ self.key += 1;
+ self.index = 0;
+ }
+ self.index += 1;
+ self.key
+ }
+}
+
+
+struct GroupInner<K, I, F>
+ where I: Iterator
+{
+ key: F,
+ iter: I,
+ current_key: Option<K>,
+ current_elt: Option<I::Item>,
+ /// flag set if iterator is exhausted
+ done: bool,
+ /// Index of group we are currently buffering or visiting
+ top_group: usize,
+ /// Least index for which we still have elements buffered
+ oldest_buffered_group: usize,
+ /// Group index for `buffer[0]` -- the slots
+ /// bottom_group..oldest_buffered_group are unused and will be erased when
+ /// that range is large enough.
+ bottom_group: usize,
+ /// Buffered groups, from `bottom_group` (index 0) to `top_group`.
+ buffer: Vec<vec::IntoIter<I::Item>>,
+ /// index of last group iter that was dropped, usize::MAX == none
+ dropped_group: usize,
+}
+
+impl<K, I, F> GroupInner<K, I, F>
+ where I: Iterator,
+ F: for<'a> KeyFunction<&'a I::Item, Key=K>,
+ K: PartialEq,
+{
+ /// `client`: Index of group that requests next element
+ #[inline(always)]
+ fn step(&mut self, client: usize) -> Option<I::Item> {
+ /*
+ println!("client={}, bottom_group={}, oldest_buffered_group={}, top_group={}, buffers=[{}]",
+ client, self.bottom_group, self.oldest_buffered_group,
+ self.top_group,
+ self.buffer.iter().map(|elt| elt.len()).format(", "));
+ */
+ if client < self.oldest_buffered_group {
+ None
+ } else if client < self.top_group ||
+ (client == self.top_group &&
+ self.buffer.len() > self.top_group - self.bottom_group)
+ {
+ self.lookup_buffer(client)
+ } else if self.done {
+ None
+ } else if self.top_group == client {
+ self.step_current()
+ } else {
+ self.step_buffering(client)
+ }
+ }
+
+ #[inline(never)]
+ fn lookup_buffer(&mut self, client: usize) -> Option<I::Item> {
+ // if `bufidx` doesn't exist in self.buffer, it might be empty
+ let bufidx = client - self.bottom_group;
+ if client < self.oldest_buffered_group {
+ return None;
+ }
+ let elt = self.buffer.get_mut(bufidx).and_then(|queue| queue.next());
+ if elt.is_none() && client == self.oldest_buffered_group {
+ // FIXME: VecDeque is unfortunately not zero allocation when empty,
+ // so we do this job manually.
+ // `bottom_group..oldest_buffered_group` is unused, and if it's large enough, erase it.
+ self.oldest_buffered_group += 1;
+ // skip forward further empty queues too
+ while self.buffer.get(self.oldest_buffered_group - self.bottom_group)
+ .map_or(false, |buf| buf.len() == 0)
+ {
+ self.oldest_buffered_group += 1;
+ }
+
+ let nclear = self.oldest_buffered_group - self.bottom_group;
+ if nclear > 0 && nclear >= self.buffer.len() / 2 {
+ let mut i = 0;
+ self.buffer.retain(|buf| {
+ i += 1;
+ debug_assert!(buf.len() == 0 || i > nclear);
+ i > nclear
+ });
+ self.bottom_group = self.oldest_buffered_group;
+ }
+ }
+ elt
+ }
+
+ /// Take the next element from the iterator, and set the done
+ /// flag if exhausted. Must not be called after done.
+ #[inline(always)]
+ fn next_element(&mut self) -> Option<I::Item> {
+ debug_assert!(!self.done);
+ match self.iter.next() {
+ None => { self.done = true; None }
+ otherwise => otherwise,
+ }
+ }
+
+
+ #[inline(never)]
+ fn step_buffering(&mut self, client: usize) -> Option<I::Item> {
+ // requested a later group -- walk through the current group up to
+ // the requested group index, and buffer the elements (unless
+ // the group is marked as dropped).
+ // Because the `Groups` iterator is always the first to request
+ // each group index, client is the next index efter top_group.
+ debug_assert!(self.top_group + 1 == client);
+ let mut group = Vec::new();
+
+ if let Some(elt) = self.current_elt.take() {
+ if self.top_group != self.dropped_group {
+ group.push(elt);
+ }
+ }
+ let mut first_elt = None; // first element of the next group
+
+ while let Some(elt) = self.next_element() {
+ let key = self.key.call_mut(&elt);
+ match self.current_key.take() {
+ None => {}
+ Some(old_key) => if old_key != key {
+ self.current_key = Some(key);
+ first_elt = Some(elt);
+ break;
+ },
+ }
+ self.current_key = Some(key);
+ if self.top_group != self.dropped_group {
+ group.push(elt);
+ }
+ }
+
+ if self.top_group != self.dropped_group {
+ self.push_next_group(group);
+ }
+ if first_elt.is_some() {
+ self.top_group += 1;
+ debug_assert!(self.top_group == client);
+ }
+ first_elt
+ }
+
+ fn push_next_group(&mut self, group: Vec<I::Item>) {
+ // When we add a new buffered group, fill up slots between oldest_buffered_group and top_group
+ while self.top_group - self.bottom_group > self.buffer.len() {
+ if self.buffer.is_empty() {
+ self.bottom_group += 1;
+ self.oldest_buffered_group += 1;
+ } else {
+ self.buffer.push(Vec::new().into_iter());
+ }
+ }
+ self.buffer.push(group.into_iter());
+ debug_assert!(self.top_group + 1 - self.bottom_group == self.buffer.len());
+ }
+
+ /// This is the immediate case, where we use no buffering
+ #[inline]
+ fn step_current(&mut self) -> Option<I::Item> {
+ debug_assert!(!self.done);
+ if let elt @ Some(..) = self.current_elt.take() {
+ return elt;
+ }
+ match self.next_element() {
+ None => None,
+ Some(elt) => {
+ let key = self.key.call_mut(&elt);
+ match self.current_key.take() {
+ None => {}
+ Some(old_key) => if old_key != key {
+ self.current_key = Some(key);
+ self.current_elt = Some(elt);
+ self.top_group += 1;
+ return None;
+ },
+ }
+ self.current_key = Some(key);
+ Some(elt)
+ }
+ }
+ }
+
+ /// Request the just started groups' key.
+ ///
+ /// `client`: Index of group
+ ///
+ /// **Panics** if no group key is available.
+ fn group_key(&mut self, client: usize) -> K {
+ // This can only be called after we have just returned the first
+ // element of a group.
+ // Perform this by simply buffering one more element, grabbing the
+ // next key.
+ debug_assert!(!self.done);
+ debug_assert!(client == self.top_group);
+ debug_assert!(self.current_key.is_some());
+ debug_assert!(self.current_elt.is_none());
+ let old_key = self.current_key.take().unwrap();
+ if let Some(elt) = self.next_element() {
+ let key = self.key.call_mut(&elt);
+ if old_key != key {
+ self.top_group += 1;
+ }
+ self.current_key = Some(key);
+ self.current_elt = Some(elt);
+ }
+ old_key
+ }
+}
+
+impl<K, I, F> GroupInner<K, I, F>
+ where I: Iterator,
+{
+ /// Called when a group is dropped
+ fn drop_group(&mut self, client: usize) {
+ // It's only useful to track the maximal index
+ if self.dropped_group == !0 || client > self.dropped_group {
+ self.dropped_group = client;
+ }
+ }
+}
+
+/// `GroupBy` is the storage for the lazy grouping operation.
+///
+/// If the groups are consumed in their original order, or if each
+/// group is dropped without keeping it around, then `GroupBy` uses
+/// no allocations. It needs allocations only if several group iterators
+/// are alive at the same time.
+///
+/// This type implements [`IntoIterator`] (it is **not** an iterator
+/// itself), because the group iterators need to borrow from this
+/// value. It should be stored in a local variable or temporary and
+/// iterated.
+///
+/// See [`.group_by()`](crate::Itertools::group_by) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct GroupBy<K, I, F>
+ where I: Iterator,
+{
+ inner: RefCell<GroupInner<K, I, F>>,
+ // the group iterator's current index. Keep this in the main value
+ // so that simultaneous iterators all use the same state.
+ index: Cell<usize>,
+}
+
+/// Create a new
+pub fn new<K, J, F>(iter: J, f: F) -> GroupBy<K, J::IntoIter, F>
+ where J: IntoIterator,
+ F: FnMut(&J::Item) -> K,
+{
+ GroupBy {
+ inner: RefCell::new(GroupInner {
+ key: f,
+ iter: iter.into_iter(),
+ current_key: None,
+ current_elt: None,
+ done: false,
+ top_group: 0,
+ oldest_buffered_group: 0,
+ bottom_group: 0,
+ buffer: Vec::new(),
+ dropped_group: !0,
+ }),
+ index: Cell::new(0),
+ }
+}
+
+impl<K, I, F> GroupBy<K, I, F>
+ where I: Iterator,
+{
+ /// `client`: Index of group that requests next element
+ fn step(&self, client: usize) -> Option<I::Item>
+ where F: FnMut(&I::Item) -> K,
+ K: PartialEq,
+ {
+ self.inner.borrow_mut().step(client)
+ }
+
+ /// `client`: Index of group
+ fn drop_group(&self, client: usize) {
+ self.inner.borrow_mut().drop_group(client);
+ }
+}
+
+impl<'a, K, I, F> IntoIterator for &'a GroupBy<K, I, F>
+ where I: Iterator,
+ I::Item: 'a,
+ F: FnMut(&I::Item) -> K,
+ K: PartialEq
+{
+ type Item = (K, Group<'a, K, I, F>);
+ type IntoIter = Groups<'a, K, I, F>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ Groups { parent: self }
+ }
+}
+
+
+/// An iterator that yields the Group iterators.
+///
+/// Iterator element type is `(K, Group)`:
+/// the group's key `K` and the group's iterator.
+///
+/// See [`.group_by()`](crate::Itertools::group_by) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Groups<'a, K: 'a, I: 'a, F: 'a>
+ where I: Iterator,
+ I::Item: 'a
+{
+ parent: &'a GroupBy<K, I, F>,
+}
+
+impl<'a, K, I, F> Iterator for Groups<'a, K, I, F>
+ where I: Iterator,
+ I::Item: 'a,
+ F: FnMut(&I::Item) -> K,
+ K: PartialEq
+{
+ type Item = (K, Group<'a, K, I, F>);
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ let index = self.parent.index.get();
+ self.parent.index.set(index + 1);
+ let inner = &mut *self.parent.inner.borrow_mut();
+ inner.step(index).map(|elt| {
+ let key = inner.group_key(index);
+ (key, Group {
+ parent: self.parent,
+ index,
+ first: Some(elt),
+ })
+ })
+ }
+}
+
+/// An iterator for the elements in a single group.
+///
+/// Iterator element type is `I::Item`.
+pub struct Group<'a, K: 'a, I: 'a, F: 'a>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ parent: &'a GroupBy<K, I, F>,
+ index: usize,
+ first: Option<I::Item>,
+}
+
+impl<'a, K, I, F> Drop for Group<'a, K, I, F>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ fn drop(&mut self) {
+ self.parent.drop_group(self.index);
+ }
+}
+
+impl<'a, K, I, F> Iterator for Group<'a, K, I, F>
+ where I: Iterator,
+ I::Item: 'a,
+ F: FnMut(&I::Item) -> K,
+ K: PartialEq,
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ if let elt @ Some(..) = self.first.take() {
+ return elt;
+ }
+ self.parent.step(self.index)
+ }
+}
+
+///// IntoChunks /////
+
+/// Create a new
+pub fn new_chunks<J>(iter: J, size: usize) -> IntoChunks<J::IntoIter>
+ where J: IntoIterator,
+{
+ IntoChunks {
+ inner: RefCell::new(GroupInner {
+ key: ChunkIndex::new(size),
+ iter: iter.into_iter(),
+ current_key: None,
+ current_elt: None,
+ done: false,
+ top_group: 0,
+ oldest_buffered_group: 0,
+ bottom_group: 0,
+ buffer: Vec::new(),
+ dropped_group: !0,
+ }),
+ index: Cell::new(0),
+ }
+}
+
+
+/// `ChunkLazy` is the storage for a lazy chunking operation.
+///
+/// `IntoChunks` behaves just like `GroupBy`: it is iterable, and
+/// it only buffers if several chunk iterators are alive at the same time.
+///
+/// This type implements [`IntoIterator`] (it is **not** an iterator
+/// itself), because the chunk iterators need to borrow from this
+/// value. It should be stored in a local variable or temporary and
+/// iterated.
+///
+/// Iterator element type is `Chunk`, each chunk's iterator.
+///
+/// See [`.chunks()`](crate::Itertools::chunks) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct IntoChunks<I>
+ where I: Iterator,
+{
+ inner: RefCell<GroupInner<usize, I, ChunkIndex>>,
+ // the chunk iterator's current index. Keep this in the main value
+ // so that simultaneous iterators all use the same state.
+ index: Cell<usize>,
+}
+
+
+impl<I> IntoChunks<I>
+ where I: Iterator,
+{
+ /// `client`: Index of chunk that requests next element
+ fn step(&self, client: usize) -> Option<I::Item> {
+ self.inner.borrow_mut().step(client)
+ }
+
+ /// `client`: Index of chunk
+ fn drop_group(&self, client: usize) {
+ self.inner.borrow_mut().drop_group(client);
+ }
+}
+
+impl<'a, I> IntoIterator for &'a IntoChunks<I>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ type Item = Chunk<'a, I>;
+ type IntoIter = Chunks<'a, I>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ Chunks {
+ parent: self,
+ }
+ }
+}
+
+
+/// An iterator that yields the Chunk iterators.
+///
+/// Iterator element type is `Chunk`.
+///
+/// See [`.chunks()`](crate::Itertools::chunks) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Chunks<'a, I: 'a>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ parent: &'a IntoChunks<I>,
+}
+
+impl<'a, I> Iterator for Chunks<'a, I>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ type Item = Chunk<'a, I>;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ let index = self.parent.index.get();
+ self.parent.index.set(index + 1);
+ let inner = &mut *self.parent.inner.borrow_mut();
+ inner.step(index).map(|elt| {
+ Chunk {
+ parent: self.parent,
+ index,
+ first: Some(elt),
+ }
+ })
+ }
+}
+
+/// An iterator for the elements in a single chunk.
+///
+/// Iterator element type is `I::Item`.
+pub struct Chunk<'a, I: 'a>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ parent: &'a IntoChunks<I>,
+ index: usize,
+ first: Option<I::Item>,
+}
+
+impl<'a, I> Drop for Chunk<'a, I>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ fn drop(&mut self) {
+ self.parent.drop_group(self.index);
+ }
+}
+
+impl<'a, I> Iterator for Chunk<'a, I>
+ where I: Iterator,
+ I::Item: 'a,
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ if let elt @ Some(..) = self.first.take() {
+ return elt;
+ }
+ self.parent.step(self.index)
+ }
+}
--- /dev/null
+#![cfg(feature = "use_std")]
+
+use crate::MinMaxResult;
+use std::collections::HashMap;
+use std::cmp::Ordering;
+use std::hash::Hash;
+use std::iter::Iterator;
+use std::ops::{Add, Mul};
+
+/// A wrapper to allow for an easy [`into_grouping_map_by`](crate::Itertools::into_grouping_map_by)
+#[derive(Clone, Debug)]
+pub struct MapForGrouping<I, F>(I, F);
+
+impl<I, F> MapForGrouping<I, F> {
+ pub(crate) fn new(iter: I, key_mapper: F) -> Self {
+ Self(iter, key_mapper)
+ }
+}
+
+impl<K, V, I, F> Iterator for MapForGrouping<I, F>
+ where I: Iterator<Item = V>,
+ K: Hash + Eq,
+ F: FnMut(&V) -> K,
+{
+ type Item = (K, V);
+ fn next(&mut self) -> Option<Self::Item> {
+ self.0.next().map(|val| ((self.1)(&val), val))
+ }
+}
+
+/// Creates a new `GroupingMap` from `iter`
+pub fn new<I, K, V>(iter: I) -> GroupingMap<I>
+ where I: Iterator<Item = (K, V)>,
+ K: Hash + Eq,
+{
+ GroupingMap { iter }
+}
+
+/// `GroupingMapBy` is an intermediate struct for efficient group-and-fold operations.
+///
+/// See [`GroupingMap`] for more informations.
+pub type GroupingMapBy<I, F> = GroupingMap<MapForGrouping<I, F>>;
+
+/// `GroupingMap` is an intermediate struct for efficient group-and-fold operations.
+/// It groups elements by their key and at the same time fold each group
+/// using some aggregating operation.
+///
+/// No method on this struct performs temporary allocations.
+#[derive(Clone, Debug)]
+#[must_use = "GroupingMap is lazy and do nothing unless consumed"]
+pub struct GroupingMap<I> {
+ iter: I,
+}
+
+impl<I, K, V> GroupingMap<I>
+ where I: Iterator<Item = (K, V)>,
+ K: Hash + Eq,
+{
+ /// This is the generic way to perform any operation on a `GroupingMap`.
+ /// It's suggested to use this method only to implement custom operations
+ /// when the already provided ones are not enough.
+ ///
+ /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements
+ /// of each group sequentially, passing the previously accumulated value, a reference to the key
+ /// and the current element as arguments, and stores the results in an `HashMap`.
+ ///
+ /// The `operation` function is invoked on each element with the following parameters:
+ /// - the current value of the accumulator of the group if there is currently one;
+ /// - a reference to the key of the group this element belongs to;
+ /// - the element from the source being aggregated;
+ ///
+ /// If `operation` returns `Some(element)` then the accumulator is updated with `element`,
+ /// otherwise the previous accumulation is discarded.
+ ///
+ /// Return a `HashMap` associating the key of each group with the result of aggregation of
+ /// that group's elements. If the aggregation of the last element of a group discards the
+ /// accumulator then there won't be an entry associated to that group's key.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![2, 8, 5, 7, 9, 0, 4, 10];
+ /// let lookup = data.into_iter()
+ /// .into_grouping_map_by(|&n| n % 4)
+ /// .aggregate(|acc, _key, val| {
+ /// if val == 0 || val == 10 {
+ /// None
+ /// } else {
+ /// Some(acc.unwrap_or(0) + val)
+ /// }
+ /// });
+ ///
+ /// assert_eq!(lookup[&0], 4); // 0 resets the accumulator so only 4 is summed
+ /// assert_eq!(lookup[&1], 5 + 9);
+ /// assert_eq!(lookup.get(&2), None); // 10 resets the accumulator and nothing is summed afterward
+ /// assert_eq!(lookup[&3], 7);
+ /// assert_eq!(lookup.len(), 3); // The final keys are only 0, 1 and 2
+ /// ```
+ pub fn aggregate<FO, R>(self, mut operation: FO) -> HashMap<K, R>
+ where FO: FnMut(Option<R>, &K, V) -> Option<R>,
+ {
+ let mut destination_map = HashMap::new();
+
+ self.iter.for_each(|(key, val)| {
+ let acc = destination_map.remove(&key);
+ if let Some(op_res) = operation(acc, &key, val) {
+ destination_map.insert(key, op_res);
+ }
+ });
+
+ destination_map
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements
+ /// of each group sequentially, passing the previously accumulated value, a reference to the key
+ /// and the current element as arguments, and stores the results in a new map.
+ ///
+ /// `init` is the value from which will be cloned the initial value of each accumulator.
+ ///
+ /// `operation` is a function that is invoked on each element with the following parameters:
+ /// - the current value of the accumulator of the group;
+ /// - a reference to the key of the group this element belongs to;
+ /// - the element from the source being accumulated.
+ ///
+ /// Return a `HashMap` associating the key of each group with the result of folding that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = (1..=7)
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .fold(0, |acc, _key, val| acc + val);
+ ///
+ /// assert_eq!(lookup[&0], 3 + 6);
+ /// assert_eq!(lookup[&1], 1 + 4 + 7);
+ /// assert_eq!(lookup[&2], 2 + 5);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn fold<FO, R>(self, init: R, mut operation: FO) -> HashMap<K, R>
+ where R: Clone,
+ FO: FnMut(R, &K, V) -> R,
+ {
+ self.aggregate(|acc, key, val| {
+ let acc = acc.unwrap_or_else(|| init.clone());
+ Some(operation(acc, key, val))
+ })
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements
+ /// of each group sequentially, passing the previously accumulated value, a reference to the key
+ /// and the current element as arguments, and stores the results in a new map.
+ ///
+ /// This is similar to [`fold`] but the initial value of the accumulator is the first element of the group.
+ ///
+ /// `operation` is a function that is invoked on each element with the following parameters:
+ /// - the current value of the accumulator of the group;
+ /// - a reference to the key of the group this element belongs to;
+ /// - the element from the source being accumulated.
+ ///
+ /// Return a `HashMap` associating the key of each group with the result of folding that group's elements.
+ ///
+ /// [`fold`]: GroupingMap::fold
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = (1..=7)
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .fold_first(|acc, _key, val| acc + val);
+ ///
+ /// assert_eq!(lookup[&0], 3 + 6);
+ /// assert_eq!(lookup[&1], 1 + 4 + 7);
+ /// assert_eq!(lookup[&2], 2 + 5);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn fold_first<FO>(self, mut operation: FO) -> HashMap<K, V>
+ where FO: FnMut(V, &K, V) -> V,
+ {
+ self.aggregate(|acc, key, val| {
+ Some(match acc {
+ Some(acc) => operation(acc, key, val),
+ None => val,
+ })
+ })
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and collects the elements of each group in
+ /// an instance of `C`. The iteration order is preserved when inserting elements.
+ ///
+ /// Return a `HashMap` associating the key of each group with the collection containing that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use std::collections::HashSet;
+ ///
+ /// let lookup = vec![0, 1, 2, 3, 4, 5, 6, 2, 3, 6].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .collect::<HashSet<_>>();
+ ///
+ /// assert_eq!(lookup[&0], vec![0, 3, 6].into_iter().collect::<HashSet<_>>());
+ /// assert_eq!(lookup[&1], vec![1, 4].into_iter().collect::<HashSet<_>>());
+ /// assert_eq!(lookup[&2], vec![2, 5].into_iter().collect::<HashSet<_>>());
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn collect<C>(self) -> HashMap<K, C>
+ where C: Default + Extend<V>,
+ {
+ let mut destination_map = HashMap::new();
+
+ self.iter.for_each(|(key, val)| {
+ destination_map.entry(key).or_insert_with(C::default).extend(Some(val));
+ });
+
+ destination_map
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the maximum of each group.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .max();
+ ///
+ /// assert_eq!(lookup[&0], 12);
+ /// assert_eq!(lookup[&1], 7);
+ /// assert_eq!(lookup[&2], 8);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn max(self) -> HashMap<K, V>
+ where V: Ord,
+ {
+ self.max_by(|_, v1, v2| V::cmp(v1, v2))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the maximum of each group
+ /// with respect to the specified comparison function.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .max_by(|_key, x, y| y.cmp(x));
+ ///
+ /// assert_eq!(lookup[&0], 3);
+ /// assert_eq!(lookup[&1], 1);
+ /// assert_eq!(lookup[&2], 5);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn max_by<F>(self, mut compare: F) -> HashMap<K, V>
+ where F: FnMut(&K, &V, &V) -> Ordering,
+ {
+ self.fold_first(|acc, key, val| match compare(key, &acc, &val) {
+ Ordering::Less | Ordering::Equal => val,
+ Ordering::Greater => acc
+ })
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the element of each group
+ /// that gives the maximum from the specified function.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .max_by_key(|_key, &val| val % 4);
+ ///
+ /// assert_eq!(lookup[&0], 3);
+ /// assert_eq!(lookup[&1], 7);
+ /// assert_eq!(lookup[&2], 5);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn max_by_key<F, CK>(self, mut f: F) -> HashMap<K, V>
+ where F: FnMut(&K, &V) -> CK,
+ CK: Ord,
+ {
+ self.max_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2)))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the minimum of each group.
+ ///
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .min();
+ ///
+ /// assert_eq!(lookup[&0], 3);
+ /// assert_eq!(lookup[&1], 1);
+ /// assert_eq!(lookup[&2], 5);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn min(self) -> HashMap<K, V>
+ where V: Ord,
+ {
+ self.min_by(|_, v1, v2| V::cmp(v1, v2))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the minimum of each group
+ /// with respect to the specified comparison function.
+ ///
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .min_by(|_key, x, y| y.cmp(x));
+ ///
+ /// assert_eq!(lookup[&0], 12);
+ /// assert_eq!(lookup[&1], 7);
+ /// assert_eq!(lookup[&2], 8);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn min_by<F>(self, mut compare: F) -> HashMap<K, V>
+ where F: FnMut(&K, &V, &V) -> Ordering,
+ {
+ self.fold_first(|acc, key, val| match compare(key, &acc, &val) {
+ Ordering::Less | Ordering::Equal => acc,
+ Ordering::Greater => val
+ })
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and finds the element of each group
+ /// that gives the minimum from the specified function.
+ ///
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .min_by_key(|_key, &val| val % 4);
+ ///
+ /// assert_eq!(lookup[&0], 12);
+ /// assert_eq!(lookup[&1], 4);
+ /// assert_eq!(lookup[&2], 8);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn min_by_key<F, CK>(self, mut f: F) -> HashMap<K, V>
+ where F: FnMut(&K, &V) -> CK,
+ CK: Ord,
+ {
+ self.min_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2)))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and find the maximum and minimum of
+ /// each group.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// See [.minmax()](crate::Itertools::minmax) for the non-grouping version.
+ ///
+ /// Differences from the non grouping version:
+ /// - It never produces a `MinMaxResult::NoElements`
+ /// - It doesn't have any speedup
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{OneElement, MinMax};
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .minmax();
+ ///
+ /// assert_eq!(lookup[&0], MinMax(3, 12));
+ /// assert_eq!(lookup[&1], MinMax(1, 7));
+ /// assert_eq!(lookup[&2], OneElement(5));
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn minmax(self) -> HashMap<K, MinMaxResult<V>>
+ where V: Ord,
+ {
+ self.minmax_by(|_, v1, v2| V::cmp(v1, v2))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and find the maximum and minimum of
+ /// each group with respect to the specified comparison function.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// It has the same differences from the non-grouping version as `minmax`.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{OneElement, MinMax};
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .minmax_by(|_key, x, y| y.cmp(x));
+ ///
+ /// assert_eq!(lookup[&0], MinMax(12, 3));
+ /// assert_eq!(lookup[&1], MinMax(7, 1));
+ /// assert_eq!(lookup[&2], OneElement(5));
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn minmax_by<F>(self, mut compare: F) -> HashMap<K, MinMaxResult<V>>
+ where F: FnMut(&K, &V, &V) -> Ordering,
+ {
+ self.aggregate(|acc, key, val| {
+ Some(match acc {
+ Some(MinMaxResult::OneElement(e)) => {
+ if compare(key, &val, &e) == Ordering::Less {
+ MinMaxResult::MinMax(val, e)
+ } else {
+ MinMaxResult::MinMax(e, val)
+ }
+ }
+ Some(MinMaxResult::MinMax(min, max)) => {
+ if compare(key, &val, &min) == Ordering::Less {
+ MinMaxResult::MinMax(val, max)
+ } else if compare(key, &val, &max) != Ordering::Less {
+ MinMaxResult::MinMax(min, val)
+ } else {
+ MinMaxResult::MinMax(min, max)
+ }
+ }
+ None => MinMaxResult::OneElement(val),
+ Some(MinMaxResult::NoElements) => unreachable!(),
+ })
+ })
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and find the elements of each group
+ /// that gives the minimum and maximum from the specified function.
+ ///
+ /// If several elements are equally maximum, the last element is picked.
+ /// If several elements are equally minimum, the first element is picked.
+ ///
+ /// It has the same differences from the non-grouping version as `minmax`.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{OneElement, MinMax};
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .minmax_by_key(|_key, &val| val % 4);
+ ///
+ /// assert_eq!(lookup[&0], MinMax(12, 3));
+ /// assert_eq!(lookup[&1], MinMax(4, 7));
+ /// assert_eq!(lookup[&2], OneElement(5));
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn minmax_by_key<F, CK>(self, mut f: F) -> HashMap<K, MinMaxResult<V>>
+ where F: FnMut(&K, &V) -> CK,
+ CK: Ord,
+ {
+ self.minmax_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2)))
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and sums them.
+ ///
+ /// This is just a shorthand for `self.fold_first(|acc, _, val| acc + val)`.
+ /// It is more limited than `Iterator::sum` since it doesn't use the `Sum` trait.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the sum of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .sum();
+ ///
+ /// assert_eq!(lookup[&0], 3 + 9 + 12);
+ /// assert_eq!(lookup[&1], 1 + 4 + 7);
+ /// assert_eq!(lookup[&2], 5 + 8);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn sum(self) -> HashMap<K, V>
+ where V: Add<V, Output = V>
+ {
+ self.fold_first(|acc, _, val| acc + val)
+ }
+
+ /// Groups elements from the `GroupingMap` source by key and multiply them.
+ ///
+ /// This is just a shorthand for `self.fold_first(|acc, _, val| acc * val)`.
+ /// It is more limited than `Iterator::product` since it doesn't use the `Product` trait.
+ ///
+ /// Returns a `HashMap` associating the key of each group with the product of that group's elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter()
+ /// .into_grouping_map_by(|&n| n % 3)
+ /// .product();
+ ///
+ /// assert_eq!(lookup[&0], 3 * 9 * 12);
+ /// assert_eq!(lookup[&1], 1 * 4 * 7);
+ /// assert_eq!(lookup[&2], 5 * 8);
+ /// assert_eq!(lookup.len(), 3);
+ /// ```
+ pub fn product(self) -> HashMap<K, V>
+ where V: Mul<V, Output = V>,
+ {
+ self.fold_first(|acc, _, val| acc * val)
+ }
+}
--- /dev/null
+//!
+//! Implementation's internal macros
+
+macro_rules! debug_fmt_fields {
+ ($tyname:ident, $($($field:tt/*TODO ideally we would accept ident or tuple element here*/).+),*) => {
+ fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+ f.debug_struct(stringify!($tyname))
+ $(
+ .field(stringify!($($field).+), &self.$($field).+)
+ )*
+ .finish()
+ }
+ }
+}
+
+macro_rules! clone_fields {
+ ($($field:ident),*) => {
+ #[inline] // TODO is this sensible?
+ fn clone(&self) -> Self {
+ Self {
+ $($field: self.$field.clone(),)*
+ }
+ }
+ }
+}
+
+macro_rules! ignore_ident{
+ ($id:ident, $($t:tt)*) => {$($t)*};
+}
--- /dev/null
+use std::iter::{Fuse, FusedIterator};
+use super::size_hint;
+
+pub trait IntersperseElement<Item> {
+ fn generate(&mut self) -> Item;
+}
+
+#[derive(Debug, Clone)]
+pub struct IntersperseElementSimple<Item>(Item);
+
+impl<Item: Clone> IntersperseElement<Item> for IntersperseElementSimple<Item> {
+ fn generate(&mut self) -> Item {
+ self.0.clone()
+ }
+}
+
+/// An iterator adaptor to insert a particular value
+/// between each element of the adapted iterator.
+///
+/// Iterator element type is `I::Item`
+///
+/// This iterator is *fused*.
+///
+/// See [`.intersperse()`](crate::Itertools::intersperse) for more information.
+pub type Intersperse<I> = IntersperseWith<I, IntersperseElementSimple<<I as Iterator>::Item>>;
+
+/// Create a new Intersperse iterator
+pub fn intersperse<I>(iter: I, elt: I::Item) -> Intersperse<I>
+ where I: Iterator,
+{
+ intersperse_with(iter, IntersperseElementSimple(elt))
+}
+
+impl<Item, F: FnMut()->Item> IntersperseElement<Item> for F {
+ fn generate(&mut self) -> Item {
+ self()
+ }
+}
+
+/// An iterator adaptor to insert a particular value created by a function
+/// between each element of the adapted iterator.
+///
+/// Iterator element type is `I::Item`
+///
+/// This iterator is *fused*.
+///
+/// See [`.intersperse_with()`](crate::Itertools::intersperse_with) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Clone, Debug)]
+pub struct IntersperseWith<I, ElemF>
+ where I: Iterator,
+{
+ element: ElemF,
+ iter: Fuse<I>,
+ peek: Option<I::Item>,
+}
+
+/// Create a new `IntersperseWith` iterator
+pub fn intersperse_with<I, ElemF>(iter: I, elt: ElemF) -> IntersperseWith<I, ElemF>
+ where I: Iterator,
+{
+ let mut iter = iter.fuse();
+ IntersperseWith {
+ peek: iter.next(),
+ iter,
+ element: elt,
+ }
+}
+
+impl<I, ElemF> Iterator for IntersperseWith<I, ElemF>
+ where I: Iterator,
+ ElemF: IntersperseElement<I::Item>
+{
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.peek.is_some() {
+ self.peek.take()
+ } else {
+ self.peek = self.iter.next();
+ if self.peek.is_some() {
+ Some(self.element.generate())
+ } else {
+ None
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // 2 * SH + { 1 or 0 }
+ let has_peek = self.peek.is_some() as usize;
+ let sh = self.iter.size_hint();
+ size_hint::add_scalar(size_hint::add(sh, sh), has_peek)
+ }
+
+ fn fold<B, F>(mut self, init: B, mut f: F) -> B where
+ Self: Sized, F: FnMut(B, Self::Item) -> B,
+ {
+ let mut accum = init;
+
+ if let Some(x) = self.peek.take() {
+ accum = f(accum, x);
+ }
+
+ let element = &mut self.element;
+
+ self.iter.fold(accum,
+ |accum, x| {
+ let accum = f(accum, element.generate());
+ f(accum, x)
+ })
+ }
+}
+
+impl<I, ElemF> FusedIterator for IntersperseWith<I, ElemF>
+ where I: Iterator,
+ ElemF: IntersperseElement<I::Item>
+{}
--- /dev/null
+use alloc::collections::BinaryHeap;
+use core::cmp::Ord;
+
+pub(crate) fn k_smallest<T: Ord, I: Iterator<Item = T>>(mut iter: I, k: usize) -> BinaryHeap<T> {
+ if k == 0 { return BinaryHeap::new(); }
+
+ let mut heap = iter.by_ref().take(k).collect::<BinaryHeap<_>>();
+
+ iter.for_each(|i| {
+ debug_assert_eq!(heap.len(), k);
+ // Equivalent to heap.push(min(i, heap.pop())) but more efficient.
+ // This should be done with a single `.peek_mut().unwrap()` but
+ // `PeekMut` sifts-down unconditionally on Rust 1.46.0 and prior.
+ if *heap.peek().unwrap() > i {
+ *heap.peek_mut().unwrap() = i;
+ }
+ });
+
+ heap
+}
--- /dev/null
+use crate::size_hint;
+use crate::Itertools;
+
+use alloc::vec::Vec;
+use std::iter::FusedIterator;
+use std::mem::replace;
+use std::fmt;
+
+/// Head element and Tail iterator pair
+///
+/// `PartialEq`, `Eq`, `PartialOrd` and `Ord` are implemented by comparing sequences based on
+/// first items (which are guaranteed to exist).
+///
+/// The meanings of `PartialOrd` and `Ord` are reversed so as to turn the heap used in
+/// `KMerge` into a min-heap.
+#[derive(Debug)]
+struct HeadTail<I>
+ where I: Iterator
+{
+ head: I::Item,
+ tail: I,
+}
+
+impl<I> HeadTail<I>
+ where I: Iterator
+{
+ /// Constructs a `HeadTail` from an `Iterator`. Returns `None` if the `Iterator` is empty.
+ fn new(mut it: I) -> Option<HeadTail<I>> {
+ let head = it.next();
+ head.map(|h| {
+ HeadTail {
+ head: h,
+ tail: it,
+ }
+ })
+ }
+
+ /// Get the next element and update `head`, returning the old head in `Some`.
+ ///
+ /// Returns `None` when the tail is exhausted (only `head` then remains).
+ fn next(&mut self) -> Option<I::Item> {
+ if let Some(next) = self.tail.next() {
+ Some(replace(&mut self.head, next))
+ } else {
+ None
+ }
+ }
+
+ /// Hints at the size of the sequence, same as the `Iterator` method.
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add_scalar(self.tail.size_hint(), 1)
+ }
+}
+
+impl<I> Clone for HeadTail<I>
+ where I: Iterator + Clone,
+ I::Item: Clone
+{
+ clone_fields!(head, tail);
+}
+
+/// Make `data` a heap (min-heap w.r.t the sorting).
+fn heapify<T, S>(data: &mut [T], mut less_than: S)
+ where S: FnMut(&T, &T) -> bool
+{
+ for i in (0..data.len() / 2).rev() {
+ sift_down(data, i, &mut less_than);
+ }
+}
+
+/// Sift down element at `index` (`heap` is a min-heap wrt the ordering)
+fn sift_down<T, S>(heap: &mut [T], index: usize, mut less_than: S)
+ where S: FnMut(&T, &T) -> bool
+{
+ debug_assert!(index <= heap.len());
+ let mut pos = index;
+ let mut child = 2 * pos + 1;
+ // Require the right child to be present
+ // This allows to find the index of the smallest child without a branch
+ // that wouldn't be predicted if present
+ while child + 1 < heap.len() {
+ // pick the smaller of the two children
+ // use arithmetic to avoid an unpredictable branch
+ child += less_than(&heap[child+1], &heap[child]) as usize;
+
+ // sift down is done if we are already in order
+ if !less_than(&heap[child], &heap[pos]) {
+ return;
+ }
+ heap.swap(pos, child);
+ pos = child;
+ child = 2 * pos + 1;
+ }
+ // Check if the last (left) child was an only child
+ // if it is then it has to be compared with the parent
+ if child + 1 == heap.len() && less_than(&heap[child], &heap[pos]) {
+ heap.swap(pos, child);
+ }
+}
+
+/// An iterator adaptor that merges an abitrary number of base iterators in ascending order.
+/// If all base iterators are sorted (ascending), the result is sorted.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.kmerge()`](crate::Itertools::kmerge) for more information.
+pub type KMerge<I> = KMergeBy<I, KMergeByLt>;
+
+pub trait KMergePredicate<T> {
+ fn kmerge_pred(&mut self, a: &T, b: &T) -> bool;
+}
+
+#[derive(Clone, Debug)]
+pub struct KMergeByLt;
+
+impl<T: PartialOrd> KMergePredicate<T> for KMergeByLt {
+ fn kmerge_pred(&mut self, a: &T, b: &T) -> bool {
+ a < b
+ }
+}
+
+impl<T, F: FnMut(&T, &T)->bool> KMergePredicate<T> for F {
+ fn kmerge_pred(&mut self, a: &T, b: &T) -> bool {
+ self(a, b)
+ }
+}
+
+/// Create an iterator that merges elements of the contained iterators using
+/// the ordering function.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::kmerge`].
+///
+/// ```
+/// use itertools::kmerge;
+///
+/// for elt in kmerge(vec![vec![0, 2, 4], vec![1, 3, 5], vec![6, 7]]) {
+/// /* loop body */
+/// }
+/// ```
+pub fn kmerge<I>(iterable: I) -> KMerge<<I::Item as IntoIterator>::IntoIter>
+ where I: IntoIterator,
+ I::Item: IntoIterator,
+ <<I as IntoIterator>::Item as IntoIterator>::Item: PartialOrd
+{
+ kmerge_by(iterable, KMergeByLt)
+}
+
+/// An iterator adaptor that merges an abitrary number of base iterators
+/// according to an ordering function.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.kmerge_by()`](crate::Itertools::kmerge_by) for more
+/// information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct KMergeBy<I, F>
+ where I: Iterator,
+{
+ heap: Vec<HeadTail<I>>,
+ less_than: F,
+}
+
+impl<I, F> fmt::Debug for KMergeBy<I, F>
+ where I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug,
+{
+ debug_fmt_fields!(KMergeBy, heap);
+}
+
+/// Create an iterator that merges elements of the contained iterators.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::kmerge_by`].
+pub fn kmerge_by<I, F>(iterable: I, mut less_than: F)
+ -> KMergeBy<<I::Item as IntoIterator>::IntoIter, F>
+ where I: IntoIterator,
+ I::Item: IntoIterator,
+ F: KMergePredicate<<<I as IntoIterator>::Item as IntoIterator>::Item>,
+{
+ let iter = iterable.into_iter();
+ let (lower, _) = iter.size_hint();
+ let mut heap: Vec<_> = Vec::with_capacity(lower);
+ heap.extend(iter.filter_map(|it| HeadTail::new(it.into_iter())));
+ heapify(&mut heap, |a, b| less_than.kmerge_pred(&a.head, &b.head));
+ KMergeBy { heap, less_than }
+}
+
+impl<I, F> Clone for KMergeBy<I, F>
+ where I: Iterator + Clone,
+ I::Item: Clone,
+ F: Clone,
+{
+ clone_fields!(heap, less_than);
+}
+
+impl<I, F> Iterator for KMergeBy<I, F>
+ where I: Iterator,
+ F: KMergePredicate<I::Item>
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.heap.is_empty() {
+ return None;
+ }
+ let result = if let Some(next) = self.heap[0].next() {
+ next
+ } else {
+ self.heap.swap_remove(0).head
+ };
+ let less_than = &mut self.less_than;
+ sift_down(&mut self.heap, 0, |a, b| less_than.kmerge_pred(&a.head, &b.head));
+ Some(result)
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ #[allow(deprecated)] //TODO: once msrv hits 1.51. replace `fold1` with `reduce`
+ self.heap.iter()
+ .map(|i| i.size_hint())
+ .fold1(size_hint::add)
+ .unwrap_or((0, Some(0)))
+ }
+}
+
+impl<I, F> FusedIterator for KMergeBy<I, F>
+ where I: Iterator,
+ F: KMergePredicate<I::Item>
+{}
--- /dev/null
+use std::ops::Index;
+use alloc::vec::Vec;
+
+#[derive(Debug, Clone)]
+pub struct LazyBuffer<I: Iterator> {
+ pub it: I,
+ done: bool,
+ buffer: Vec<I::Item>,
+}
+
+impl<I> LazyBuffer<I>
+where
+ I: Iterator,
+{
+ pub fn new(it: I) -> LazyBuffer<I> {
+ LazyBuffer {
+ it,
+ done: false,
+ buffer: Vec::new(),
+ }
+ }
+
+ pub fn len(&self) -> usize {
+ self.buffer.len()
+ }
+
+ pub fn get_next(&mut self) -> bool {
+ if self.done {
+ return false;
+ }
+ if let Some(x) = self.it.next() {
+ self.buffer.push(x);
+ true
+ } else {
+ self.done = true;
+ false
+ }
+ }
+
+ pub fn prefill(&mut self, len: usize) {
+ let buffer_len = self.buffer.len();
+
+ if !self.done && len > buffer_len {
+ let delta = len - buffer_len;
+
+ self.buffer.extend(self.it.by_ref().take(delta));
+ self.done = self.buffer.len() < len;
+ }
+ }
+}
+
+impl<I, J> Index<J> for LazyBuffer<I>
+where
+ I: Iterator,
+ I::Item: Sized,
+ Vec<I::Item>: Index<J>
+{
+ type Output = <Vec<I::Item> as Index<J>>::Output;
+
+ fn index(&self, index: J) -> &Self::Output {
+ self.buffer.index(index)
+ }
+}
--- /dev/null
+#![warn(missing_docs)]
+#![crate_name="itertools"]
+#![cfg_attr(not(feature = "use_std"), no_std)]
+
+//! Extra iterator adaptors, functions and macros.
+//!
+//! To extend [`Iterator`] with methods in this crate, import
+//! the [`Itertools`] trait:
+//!
+//! ```
+//! use itertools::Itertools;
+//! ```
+//!
+//! Now, new methods like [`interleave`](Itertools::interleave)
+//! are available on all iterators:
+//!
+//! ```
+//! use itertools::Itertools;
+//!
+//! let it = (1..3).interleave(vec![-1, -2]);
+//! itertools::assert_equal(it, vec![1, -1, 2, -2]);
+//! ```
+//!
+//! Most iterator methods are also provided as functions (with the benefit
+//! that they convert parameters using [`IntoIterator`]):
+//!
+//! ```
+//! use itertools::interleave;
+//!
+//! for elt in interleave(&[1, 2, 3], &[2, 3, 4]) {
+//! /* loop body */
+//! }
+//! ```
+//!
+//! ## Crate Features
+//!
+//! - `use_std`
+//! - Enabled by default.
+//! - Disable to compile itertools using `#![no_std]`. This disables
+//! any items that depend on collections (like `group_by`, `unique`,
+//! `kmerge`, `join` and many more).
+//!
+//! ## Rust Version
+//!
+//! This version of itertools requires Rust 1.32 or later.
+#![doc(html_root_url="https://docs.rs/itertools/0.8/")]
+
+#[cfg(not(feature = "use_std"))]
+extern crate core as std;
+
+#[cfg(feature = "use_alloc")]
+extern crate alloc;
+
+#[cfg(feature = "use_alloc")]
+use alloc::{
+ string::String,
+ vec::Vec,
+};
+
+pub use either::Either;
+
+use core::borrow::Borrow;
+#[cfg(feature = "use_std")]
+use std::collections::HashMap;
+use std::iter::{IntoIterator, once};
+use std::cmp::Ordering;
+use std::fmt;
+#[cfg(feature = "use_std")]
+use std::collections::HashSet;
+#[cfg(feature = "use_std")]
+use std::hash::Hash;
+#[cfg(feature = "use_alloc")]
+use std::fmt::Write;
+#[cfg(feature = "use_alloc")]
+type VecIntoIter<T> = alloc::vec::IntoIter<T>;
+#[cfg(feature = "use_alloc")]
+use std::iter::FromIterator;
+
+#[macro_use]
+mod impl_macros;
+
+// for compatibility with no std and macros
+#[doc(hidden)]
+pub use std::iter as __std_iter;
+
+/// The concrete iterator types.
+pub mod structs {
+ pub use crate::adaptors::{
+ Dedup,
+ DedupBy,
+ DedupWithCount,
+ DedupByWithCount,
+ Interleave,
+ InterleaveShortest,
+ FilterMapOk,
+ FilterOk,
+ Product,
+ PutBack,
+ Batching,
+ MapInto,
+ MapOk,
+ Merge,
+ MergeBy,
+ TakeWhileRef,
+ WhileSome,
+ Coalesce,
+ TupleCombinations,
+ Positions,
+ Update,
+ };
+ #[allow(deprecated)]
+ pub use crate::adaptors::{MapResults, Step};
+ #[cfg(feature = "use_alloc")]
+ pub use crate::adaptors::MultiProduct;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::combinations::Combinations;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::combinations_with_replacement::CombinationsWithReplacement;
+ pub use crate::cons_tuples_impl::ConsTuples;
+ pub use crate::exactly_one_err::ExactlyOneError;
+ pub use crate::format::{Format, FormatWith};
+ pub use crate::flatten_ok::FlattenOk;
+ #[cfg(feature = "use_std")]
+ pub use crate::grouping_map::{GroupingMap, GroupingMapBy};
+ #[cfg(feature = "use_alloc")]
+ pub use crate::groupbylazy::{IntoChunks, Chunk, Chunks, GroupBy, Group, Groups};
+ pub use crate::intersperse::{Intersperse, IntersperseWith};
+ #[cfg(feature = "use_alloc")]
+ pub use crate::kmerge_impl::{KMerge, KMergeBy};
+ pub use crate::merge_join::MergeJoinBy;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::multipeek_impl::MultiPeek;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::peek_nth::PeekNth;
+ pub use crate::pad_tail::PadUsing;
+ pub use crate::peeking_take_while::PeekingTakeWhile;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::permutations::Permutations;
+ pub use crate::process_results_impl::ProcessResults;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::powerset::Powerset;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::put_back_n_impl::PutBackN;
+ #[cfg(feature = "use_alloc")]
+ pub use crate::rciter_impl::RcIter;
+ pub use crate::repeatn::RepeatN;
+ #[allow(deprecated)]
+ pub use crate::sources::{RepeatCall, Unfold, Iterate};
+ #[cfg(feature = "use_alloc")]
+ pub use crate::tee::Tee;
+ pub use crate::tuple_impl::{TupleBuffer, TupleWindows, CircularTupleWindows, Tuples};
+ #[cfg(feature = "use_std")]
+ pub use crate::duplicates_impl::{Duplicates, DuplicatesBy};
+ #[cfg(feature = "use_std")]
+ pub use crate::unique_impl::{Unique, UniqueBy};
+ pub use crate::with_position::WithPosition;
+ pub use crate::zip_eq_impl::ZipEq;
+ pub use crate::zip_longest::ZipLongest;
+ pub use crate::ziptuple::Zip;
+}
+
+/// Traits helpful for using certain `Itertools` methods in generic contexts.
+pub mod traits {
+ pub use crate::tuple_impl::HomogeneousTuple;
+}
+
+#[allow(deprecated)]
+pub use crate::structs::*;
+pub use crate::concat_impl::concat;
+pub use crate::cons_tuples_impl::cons_tuples;
+pub use crate::diff::diff_with;
+pub use crate::diff::Diff;
+#[cfg(feature = "use_alloc")]
+pub use crate::kmerge_impl::{kmerge_by};
+pub use crate::minmax::MinMaxResult;
+pub use crate::peeking_take_while::PeekingNext;
+pub use crate::process_results_impl::process_results;
+pub use crate::repeatn::repeat_n;
+#[allow(deprecated)]
+pub use crate::sources::{repeat_call, unfold, iterate};
+pub use crate::with_position::Position;
+pub use crate::unziptuple::{multiunzip, MultiUnzip};
+pub use crate::ziptuple::multizip;
+mod adaptors;
+mod either_or_both;
+pub use crate::either_or_both::EitherOrBoth;
+#[doc(hidden)]
+pub mod free;
+#[doc(inline)]
+pub use crate::free::*;
+mod concat_impl;
+mod cons_tuples_impl;
+#[cfg(feature = "use_alloc")]
+mod combinations;
+#[cfg(feature = "use_alloc")]
+mod combinations_with_replacement;
+mod exactly_one_err;
+mod diff;
+mod flatten_ok;
+#[cfg(feature = "use_std")]
+mod extrema_set;
+mod format;
+#[cfg(feature = "use_std")]
+mod grouping_map;
+#[cfg(feature = "use_alloc")]
+mod group_map;
+#[cfg(feature = "use_alloc")]
+mod groupbylazy;
+mod intersperse;
+#[cfg(feature = "use_alloc")]
+mod k_smallest;
+#[cfg(feature = "use_alloc")]
+mod kmerge_impl;
+#[cfg(feature = "use_alloc")]
+mod lazy_buffer;
+mod merge_join;
+mod minmax;
+#[cfg(feature = "use_alloc")]
+mod multipeek_impl;
+mod pad_tail;
+#[cfg(feature = "use_alloc")]
+mod peek_nth;
+mod peeking_take_while;
+#[cfg(feature = "use_alloc")]
+mod permutations;
+#[cfg(feature = "use_alloc")]
+mod powerset;
+mod process_results_impl;
+#[cfg(feature = "use_alloc")]
+mod put_back_n_impl;
+#[cfg(feature = "use_alloc")]
+mod rciter_impl;
+mod repeatn;
+mod size_hint;
+mod sources;
+#[cfg(feature = "use_alloc")]
+mod tee;
+mod tuple_impl;
+#[cfg(feature = "use_std")]
+mod duplicates_impl;
+#[cfg(feature = "use_std")]
+mod unique_impl;
+mod unziptuple;
+mod with_position;
+mod zip_eq_impl;
+mod zip_longest;
+mod ziptuple;
+
+#[macro_export]
+/// Create an iterator over the “cartesian product” of iterators.
+///
+/// Iterator element type is like `(A, B, ..., E)` if formed
+/// from iterators `(I, J, ..., M)` with element types `I::Item = A`, `J::Item = B`, etc.
+///
+/// ```
+/// # use itertools::iproduct;
+/// #
+/// # fn main() {
+/// // Iterate over the coordinates of a 4 x 4 x 4 grid
+/// // from (0, 0, 0), (0, 0, 1), .., (0, 1, 0), (0, 1, 1), .. etc until (3, 3, 3)
+/// for (i, j, k) in iproduct!(0..4, 0..4, 0..4) {
+/// // ..
+/// }
+/// # }
+/// ```
+macro_rules! iproduct {
+ (@flatten $I:expr,) => (
+ $I
+ );
+ (@flatten $I:expr, $J:expr, $($K:expr,)*) => (
+ $crate::iproduct!(@flatten $crate::cons_tuples($crate::iproduct!($I, $J)), $($K,)*)
+ );
+ ($I:expr) => (
+ $crate::__std_iter::IntoIterator::into_iter($I)
+ );
+ ($I:expr, $J:expr) => (
+ $crate::Itertools::cartesian_product($crate::iproduct!($I), $crate::iproduct!($J))
+ );
+ ($I:expr, $J:expr, $($K:expr),+) => (
+ $crate::iproduct!(@flatten $crate::iproduct!($I, $J), $($K,)+)
+ );
+}
+
+#[macro_export]
+/// Create an iterator running multiple iterators in lockstep.
+///
+/// The `izip!` iterator yields elements until any subiterator
+/// returns `None`.
+///
+/// This is a version of the standard ``.zip()`` that's supporting more than
+/// two iterators. The iterator element type is a tuple with one element
+/// from each of the input iterators. Just like ``.zip()``, the iteration stops
+/// when the shortest of the inputs reaches its end.
+///
+/// **Note:** The result of this macro is in the general case an iterator
+/// composed of repeated `.zip()` and a `.map()`; it has an anonymous type.
+/// The special cases of one and two arguments produce the equivalent of
+/// `$a.into_iter()` and `$a.into_iter().zip($b)` respectively.
+///
+/// Prefer this macro `izip!()` over [`multizip`] for the performance benefits
+/// of using the standard library `.zip()`.
+///
+/// ```
+/// # use itertools::izip;
+/// #
+/// # fn main() {
+///
+/// // iterate over three sequences side-by-side
+/// let mut results = [0, 0, 0, 0];
+/// let inputs = [3, 7, 9, 6];
+///
+/// for (r, index, input) in izip!(&mut results, 0..10, &inputs) {
+/// *r = index * 10 + input;
+/// }
+///
+/// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]);
+/// # }
+/// ```
+macro_rules! izip {
+ // @closure creates a tuple-flattening closure for .map() call. usage:
+ // @closure partial_pattern => partial_tuple , rest , of , iterators
+ // eg. izip!( @closure ((a, b), c) => (a, b, c) , dd , ee )
+ ( @closure $p:pat => $tup:expr ) => {
+ |$p| $tup
+ };
+
+ // The "b" identifier is a different identifier on each recursion level thanks to hygiene.
+ ( @closure $p:pat => ( $($tup:tt)* ) , $_iter:expr $( , $tail:expr )* ) => {
+ $crate::izip!(@closure ($p, b) => ( $($tup)*, b ) $( , $tail )*)
+ };
+
+ // unary
+ ($first:expr $(,)*) => {
+ $crate::__std_iter::IntoIterator::into_iter($first)
+ };
+
+ // binary
+ ($first:expr, $second:expr $(,)*) => {
+ $crate::izip!($first)
+ .zip($second)
+ };
+
+ // n-ary where n > 2
+ ( $first:expr $( , $rest:expr )* $(,)* ) => {
+ $crate::izip!($first)
+ $(
+ .zip($rest)
+ )*
+ .map(
+ $crate::izip!(@closure a => (a) $( , $rest )*)
+ )
+ };
+}
+
+#[macro_export]
+/// [Chain][`chain`] zero or more iterators together into one sequence.
+///
+/// The comma-separated arguments must implement [`IntoIterator`].
+/// The final argument may be followed by a trailing comma.
+///
+/// [`chain`]: Iterator::chain
+///
+/// # Examples
+///
+/// Empty invocations of `chain!` expand to an invocation of [`std::iter::empty`]:
+/// ```
+/// use std::iter;
+/// use itertools::chain;
+///
+/// let _: iter::Empty<()> = chain!();
+/// let _: iter::Empty<i8> = chain!();
+/// ```
+///
+/// Invocations of `chain!` with one argument expand to [`arg.into_iter()`](IntoIterator):
+/// ```
+/// use std::{ops::Range, slice};
+/// use itertools::chain;
+/// let _: <Range<_> as IntoIterator>::IntoIter = chain!((2..6),); // trailing comma optional!
+/// let _: <&[_] as IntoIterator>::IntoIter = chain!(&[2, 3, 4]);
+/// ```
+///
+/// Invocations of `chain!` with multiple arguments [`.into_iter()`](IntoIterator) each
+/// argument, and then [`chain`] them together:
+/// ```
+/// use std::{iter::*, ops::Range, slice};
+/// use itertools::{assert_equal, chain};
+///
+/// // e.g., this:
+/// let with_macro: Chain<Chain<Once<_>, Take<Repeat<_>>>, slice::Iter<_>> =
+/// chain![once(&0), repeat(&1).take(2), &[2, 3, 5],];
+///
+/// // ...is equivalent to this:
+/// let with_method: Chain<Chain<Once<_>, Take<Repeat<_>>>, slice::Iter<_>> =
+/// once(&0)
+/// .chain(repeat(&1).take(2))
+/// .chain(&[2, 3, 5]);
+///
+/// assert_equal(with_macro, with_method);
+/// ```
+macro_rules! chain {
+ () => {
+ core::iter::empty()
+ };
+ ($first:expr $(, $rest:expr )* $(,)?) => {
+ {
+ let iter = core::iter::IntoIterator::into_iter($first);
+ $(
+ let iter =
+ core::iter::Iterator::chain(
+ iter,
+ core::iter::IntoIterator::into_iter($rest));
+ )*
+ iter
+ }
+ };
+}
+
+/// An [`Iterator`] blanket implementation that provides extra adaptors and
+/// methods.
+///
+/// This trait defines a number of methods. They are divided into two groups:
+///
+/// * *Adaptors* take an iterator and parameter as input, and return
+/// a new iterator value. These are listed first in the trait. An example
+/// of an adaptor is [`.interleave()`](Itertools::interleave)
+///
+/// * *Regular methods* are those that don't return iterators and instead
+/// return a regular value of some other kind.
+/// [`.next_tuple()`](Itertools::next_tuple) is an example and the first regular
+/// method in the list.
+pub trait Itertools : Iterator {
+ // adaptors
+
+ /// Alternate elements from two iterators until both have run out.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (1..7).interleave(vec![-1, -2]);
+ /// itertools::assert_equal(it, vec![1, -1, 2, -2, 3, 4, 5, 6]);
+ /// ```
+ fn interleave<J>(self, other: J) -> Interleave<Self, J::IntoIter>
+ where J: IntoIterator<Item = Self::Item>,
+ Self: Sized
+ {
+ interleave(self, other)
+ }
+
+ /// Alternate elements from two iterators until at least one of them has run
+ /// out.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (1..7).interleave_shortest(vec![-1, -2]);
+ /// itertools::assert_equal(it, vec![1, -1, 2, -2, 3]);
+ /// ```
+ fn interleave_shortest<J>(self, other: J) -> InterleaveShortest<Self, J::IntoIter>
+ where J: IntoIterator<Item = Self::Item>,
+ Self: Sized
+ {
+ adaptors::interleave_shortest(self, other.into_iter())
+ }
+
+ /// An iterator adaptor to insert a particular value
+ /// between each element of the adapted iterator.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// itertools::assert_equal((0..3).intersperse(8), vec![0, 8, 1, 8, 2]);
+ /// ```
+ fn intersperse(self, element: Self::Item) -> Intersperse<Self>
+ where Self: Sized,
+ Self::Item: Clone
+ {
+ intersperse::intersperse(self, element)
+ }
+
+ /// An iterator adaptor to insert a particular value created by a function
+ /// between each element of the adapted iterator.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut i = 10;
+ /// itertools::assert_equal((0..3).intersperse_with(|| { i -= 1; i }), vec![0, 9, 1, 8, 2]);
+ /// assert_eq!(i, 8);
+ /// ```
+ fn intersperse_with<F>(self, element: F) -> IntersperseWith<Self, F>
+ where Self: Sized,
+ F: FnMut() -> Self::Item
+ {
+ intersperse::intersperse_with(self, element)
+ }
+
+ /// Create an iterator which iterates over both this and the specified
+ /// iterator simultaneously, yielding pairs of two optional elements.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// As long as neither input iterator is exhausted yet, it yields two values
+ /// via `EitherOrBoth::Both`.
+ ///
+ /// When the parameter iterator is exhausted, it only yields a value from the
+ /// `self` iterator via `EitherOrBoth::Left`.
+ ///
+ /// When the `self` iterator is exhausted, it only yields a value from the
+ /// parameter iterator via `EitherOrBoth::Right`.
+ ///
+ /// When both iterators return `None`, all further invocations of `.next()`
+ /// will return `None`.
+ ///
+ /// Iterator element type is
+ /// [`EitherOrBoth<Self::Item, J::Item>`](EitherOrBoth).
+ ///
+ /// ```rust
+ /// use itertools::EitherOrBoth::{Both, Right};
+ /// use itertools::Itertools;
+ /// let it = (0..1).zip_longest(1..3);
+ /// itertools::assert_equal(it, vec![Both(0, 1), Right(2)]);
+ /// ```
+ #[inline]
+ fn zip_longest<J>(self, other: J) -> ZipLongest<Self, J::IntoIter>
+ where J: IntoIterator,
+ Self: Sized
+ {
+ zip_longest::zip_longest(self, other.into_iter())
+ }
+
+ /// Create an iterator which iterates over both this and the specified
+ /// iterator simultaneously, yielding pairs of elements.
+ ///
+ /// **Panics** if the iterators reach an end and they are not of equal
+ /// lengths.
+ #[inline]
+ fn zip_eq<J>(self, other: J) -> ZipEq<Self, J::IntoIter>
+ where J: IntoIterator,
+ Self: Sized
+ {
+ zip_eq(self, other)
+ }
+
+ /// A “meta iterator adaptor”. Its closure receives a reference to the
+ /// iterator and may pick off as many elements as it likes, to produce the
+ /// next iterator element.
+ ///
+ /// Iterator element type is `B`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // An adaptor that gathers elements in pairs
+ /// let pit = (0..4).batching(|it| {
+ /// match it.next() {
+ /// None => None,
+ /// Some(x) => match it.next() {
+ /// None => None,
+ /// Some(y) => Some((x, y)),
+ /// }
+ /// }
+ /// });
+ ///
+ /// itertools::assert_equal(pit, vec![(0, 1), (2, 3)]);
+ /// ```
+ ///
+ fn batching<B, F>(self, f: F) -> Batching<Self, F>
+ where F: FnMut(&mut Self) -> Option<B>,
+ Self: Sized
+ {
+ adaptors::batching(self, f)
+ }
+
+ /// Return an *iterable* that can group iterator elements.
+ /// Consecutive elements that map to the same key (“runs”), are assigned
+ /// to the same group.
+ ///
+ /// `GroupBy` is the storage for the lazy grouping operation.
+ ///
+ /// If the groups are consumed in order, or if each group's iterator is
+ /// dropped without keeping it around, then `GroupBy` uses no
+ /// allocations. It needs allocations only if several group iterators
+ /// are alive at the same time.
+ ///
+ /// This type implements [`IntoIterator`] (it is **not** an iterator
+ /// itself), because the group iterators need to borrow from this
+ /// value. It should be stored in a local variable or temporary and
+ /// iterated.
+ ///
+ /// Iterator element type is `(K, Group)`: the group's key and the
+ /// group iterator.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // group data into runs of larger than zero or not.
+ /// let data = vec![1, 3, -2, -2, 1, 0, 1, 2];
+ /// // groups: |---->|------>|--------->|
+ ///
+ /// // Note: The `&` is significant here, `GroupBy` is iterable
+ /// // only by reference. You can also call `.into_iter()` explicitly.
+ /// let mut data_grouped = Vec::new();
+ /// for (key, group) in &data.into_iter().group_by(|elt| *elt >= 0) {
+ /// data_grouped.push((key, group.collect()));
+ /// }
+ /// assert_eq!(data_grouped, vec![(true, vec![1, 3]), (false, vec![-2, -2]), (true, vec![1, 0, 1, 2])]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn group_by<K, F>(self, key: F) -> GroupBy<K, Self, F>
+ where Self: Sized,
+ F: FnMut(&Self::Item) -> K,
+ K: PartialEq,
+ {
+ groupbylazy::new(self, key)
+ }
+
+ /// Return an *iterable* that can chunk the iterator.
+ ///
+ /// Yield subiterators (chunks) that each yield a fixed number elements,
+ /// determined by `size`. The last chunk will be shorter if there aren't
+ /// enough elements.
+ ///
+ /// `IntoChunks` is based on `GroupBy`: it is iterable (implements
+ /// `IntoIterator`, **not** `Iterator`), and it only buffers if several
+ /// chunk iterators are alive at the same time.
+ ///
+ /// Iterator element type is `Chunk`, each chunk's iterator.
+ ///
+ /// **Panics** if `size` is 0.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![1, 1, 2, -2, 6, 0, 3, 1];
+ /// //chunk size=3 |------->|-------->|--->|
+ ///
+ /// // Note: The `&` is significant here, `IntoChunks` is iterable
+ /// // only by reference. You can also call `.into_iter()` explicitly.
+ /// for chunk in &data.into_iter().chunks(3) {
+ /// // Check that the sum of each chunk is 4.
+ /// assert_eq!(4, chunk.sum());
+ /// }
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn chunks(self, size: usize) -> IntoChunks<Self>
+ where Self: Sized,
+ {
+ assert!(size != 0);
+ groupbylazy::new_chunks(self, size)
+ }
+
+ /// Return an iterator over all contiguous windows producing tuples of
+ /// a specific size (up to 12).
+ ///
+ /// `tuple_windows` clones the iterator elements so that they can be
+ /// part of successive windows, this makes it most suited for iterators
+ /// of references and other values that are cheap to copy.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// let mut v = Vec::new();
+ ///
+ /// // pairwise iteration
+ /// for (a, b) in (1..5).tuple_windows() {
+ /// v.push((a, b));
+ /// }
+ /// assert_eq!(v, vec![(1, 2), (2, 3), (3, 4)]);
+ ///
+ /// let mut it = (1..5).tuple_windows();
+ /// assert_eq!(Some((1, 2, 3)), it.next());
+ /// assert_eq!(Some((2, 3, 4)), it.next());
+ /// assert_eq!(None, it.next());
+ ///
+ /// // this requires a type hint
+ /// let it = (1..5).tuple_windows::<(_, _, _)>();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4)]);
+ ///
+ /// // you can also specify the complete type
+ /// use itertools::TupleWindows;
+ /// use std::ops::Range;
+ ///
+ /// let it: TupleWindows<Range<u32>, (u32, u32, u32)> = (1..5).tuple_windows();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4)]);
+ /// ```
+ fn tuple_windows<T>(self) -> TupleWindows<Self, T>
+ where Self: Sized + Iterator<Item = T::Item>,
+ T: traits::HomogeneousTuple,
+ T::Item: Clone
+ {
+ tuple_impl::tuple_windows(self)
+ }
+
+ /// Return an iterator over all windows, wrapping back to the first
+ /// elements when the window would otherwise exceed the length of the
+ /// iterator, producing tuples of a specific size (up to 12).
+ ///
+ /// `circular_tuple_windows` clones the iterator elements so that they can be
+ /// part of successive windows, this makes it most suited for iterators
+ /// of references and other values that are cheap to copy.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// let mut v = Vec::new();
+ /// for (a, b) in (1..5).circular_tuple_windows() {
+ /// v.push((a, b));
+ /// }
+ /// assert_eq!(v, vec![(1, 2), (2, 3), (3, 4), (4, 1)]);
+ ///
+ /// let mut it = (1..5).circular_tuple_windows();
+ /// assert_eq!(Some((1, 2, 3)), it.next());
+ /// assert_eq!(Some((2, 3, 4)), it.next());
+ /// assert_eq!(Some((3, 4, 1)), it.next());
+ /// assert_eq!(Some((4, 1, 2)), it.next());
+ /// assert_eq!(None, it.next());
+ ///
+ /// // this requires a type hint
+ /// let it = (1..5).circular_tuple_windows::<(_, _, _)>();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4), (3, 4, 1), (4, 1, 2)]);
+ /// ```
+ fn circular_tuple_windows<T>(self) -> CircularTupleWindows<Self, T>
+ where Self: Sized + Clone + Iterator<Item = T::Item> + ExactSizeIterator,
+ T: tuple_impl::TupleCollect + Clone,
+ T::Item: Clone
+ {
+ tuple_impl::circular_tuple_windows(self)
+ }
+ /// Return an iterator that groups the items in tuples of a specific size
+ /// (up to 12).
+ ///
+ /// See also the method [`.next_tuple()`](Itertools::next_tuple).
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// let mut v = Vec::new();
+ /// for (a, b) in (1..5).tuples() {
+ /// v.push((a, b));
+ /// }
+ /// assert_eq!(v, vec![(1, 2), (3, 4)]);
+ ///
+ /// let mut it = (1..7).tuples();
+ /// assert_eq!(Some((1, 2, 3)), it.next());
+ /// assert_eq!(Some((4, 5, 6)), it.next());
+ /// assert_eq!(None, it.next());
+ ///
+ /// // this requires a type hint
+ /// let it = (1..7).tuples::<(_, _, _)>();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (4, 5, 6)]);
+ ///
+ /// // you can also specify the complete type
+ /// use itertools::Tuples;
+ /// use std::ops::Range;
+ ///
+ /// let it: Tuples<Range<u32>, (u32, u32, u32)> = (1..7).tuples();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (4, 5, 6)]);
+ /// ```
+ ///
+ /// See also [`Tuples::into_buffer`].
+ fn tuples<T>(self) -> Tuples<Self, T>
+ where Self: Sized + Iterator<Item = T::Item>,
+ T: traits::HomogeneousTuple
+ {
+ tuple_impl::tuples(self)
+ }
+
+ /// Split into an iterator pair that both yield all elements from
+ /// the original iterator.
+ ///
+ /// **Note:** If the iterator is clonable, prefer using that instead
+ /// of using this method. Cloning is likely to be more efficient.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// let xs = vec![0, 1, 2, 3];
+ ///
+ /// let (mut t1, t2) = xs.into_iter().tee();
+ /// itertools::assert_equal(t1.next(), Some(0));
+ /// itertools::assert_equal(t2, 0..4);
+ /// itertools::assert_equal(t1, 1..4);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn tee(self) -> (Tee<Self>, Tee<Self>)
+ where Self: Sized,
+ Self::Item: Clone
+ {
+ tee::new(self)
+ }
+
+ /// Return an iterator adaptor that steps `n` elements in the base iterator
+ /// for each iteration.
+ ///
+ /// The iterator steps by yielding the next element from the base iterator,
+ /// then skipping forward `n - 1` elements.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// **Panics** if the step is 0.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (0..8).step(3);
+ /// itertools::assert_equal(it, vec![0, 3, 6]);
+ /// ```
+ #[deprecated(note="Use std .step_by() instead", since="0.8.0")]
+ #[allow(deprecated)]
+ fn step(self, n: usize) -> Step<Self>
+ where Self: Sized
+ {
+ adaptors::step(self, n)
+ }
+
+ /// Convert each item of the iterator using the [`Into`] trait.
+ ///
+ /// ```rust
+ /// use itertools::Itertools;
+ ///
+ /// (1i32..42i32).map_into::<f64>().collect_vec();
+ /// ```
+ fn map_into<R>(self) -> MapInto<Self, R>
+ where Self: Sized,
+ Self::Item: Into<R>,
+ {
+ adaptors::map_into(self)
+ }
+
+ /// See [`.map_ok()`](Itertools::map_ok).
+ #[deprecated(note="Use .map_ok() instead", since="0.10.0")]
+ fn map_results<F, T, U, E>(self, f: F) -> MapOk<Self, F>
+ where Self: Iterator<Item = Result<T, E>> + Sized,
+ F: FnMut(T) -> U,
+ {
+ self.map_ok(f)
+ }
+
+ /// Return an iterator adaptor that applies the provided closure
+ /// to every `Result::Ok` value. `Result::Err` values are
+ /// unchanged.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![Ok(41), Err(false), Ok(11)];
+ /// let it = input.into_iter().map_ok(|i| i + 1);
+ /// itertools::assert_equal(it, vec![Ok(42), Err(false), Ok(12)]);
+ /// ```
+ fn map_ok<F, T, U, E>(self, f: F) -> MapOk<Self, F>
+ where Self: Iterator<Item = Result<T, E>> + Sized,
+ F: FnMut(T) -> U,
+ {
+ adaptors::map_ok(self, f)
+ }
+
+ /// Return an iterator adaptor that filters every `Result::Ok`
+ /// value with the provided closure. `Result::Err` values are
+ /// unchanged.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![Ok(22), Err(false), Ok(11)];
+ /// let it = input.into_iter().filter_ok(|&i| i > 20);
+ /// itertools::assert_equal(it, vec![Ok(22), Err(false)]);
+ /// ```
+ fn filter_ok<F, T, E>(self, f: F) -> FilterOk<Self, F>
+ where Self: Iterator<Item = Result<T, E>> + Sized,
+ F: FnMut(&T) -> bool,
+ {
+ adaptors::filter_ok(self, f)
+ }
+
+ /// Return an iterator adaptor that filters and transforms every
+ /// `Result::Ok` value with the provided closure. `Result::Err`
+ /// values are unchanged.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![Ok(22), Err(false), Ok(11)];
+ /// let it = input.into_iter().filter_map_ok(|i| if i > 20 { Some(i * 2) } else { None });
+ /// itertools::assert_equal(it, vec![Ok(44), Err(false)]);
+ /// ```
+ fn filter_map_ok<F, T, U, E>(self, f: F) -> FilterMapOk<Self, F>
+ where Self: Iterator<Item = Result<T, E>> + Sized,
+ F: FnMut(T) -> Option<U>,
+ {
+ adaptors::filter_map_ok(self, f)
+ }
+
+ /// Return an iterator adaptor that flattens every `Result::Ok` value into
+ /// a series of `Result::Ok` values. `Result::Err` values are unchanged.
+ ///
+ /// This is useful when you have some common error type for your crate and
+ /// need to propagate it upwards, but the `Result::Ok` case needs to be flattened.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![Ok(0..2), Err(false), Ok(2..4)];
+ /// let it = input.iter().cloned().flatten_ok();
+ /// itertools::assert_equal(it.clone(), vec![Ok(0), Ok(1), Err(false), Ok(2), Ok(3)]);
+ ///
+ /// // This can also be used to propagate errors when collecting.
+ /// let output_result: Result<Vec<i32>, bool> = it.collect();
+ /// assert_eq!(output_result, Err(false));
+ /// ```
+ fn flatten_ok<T, E>(self) -> FlattenOk<Self, T, E>
+ where Self: Iterator<Item = Result<T, E>> + Sized,
+ T: IntoIterator
+ {
+ flatten_ok::flatten_ok(self)
+ }
+
+ /// Return an iterator adaptor that merges the two base iterators in
+ /// ascending order. If both base iterators are sorted (ascending), the
+ /// result is sorted.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a = (0..11).step(3);
+ /// let b = (0..11).step(5);
+ /// let it = a.merge(b);
+ /// itertools::assert_equal(it, vec![0, 0, 3, 5, 6, 9, 10]);
+ /// ```
+ fn merge<J>(self, other: J) -> Merge<Self, J::IntoIter>
+ where Self: Sized,
+ Self::Item: PartialOrd,
+ J: IntoIterator<Item = Self::Item>
+ {
+ merge(self, other)
+ }
+
+ /// Return an iterator adaptor that merges the two base iterators in order.
+ /// This is much like [`.merge()`](Itertools::merge) but allows for a custom ordering.
+ ///
+ /// This can be especially useful for sequences of tuples.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a = (0..).zip("bc".chars());
+ /// let b = (0..).zip("ad".chars());
+ /// let it = a.merge_by(b, |x, y| x.1 <= y.1);
+ /// itertools::assert_equal(it, vec![(0, 'a'), (0, 'b'), (1, 'c'), (1, 'd')]);
+ /// ```
+
+ fn merge_by<J, F>(self, other: J, is_first: F) -> MergeBy<Self, J::IntoIter, F>
+ where Self: Sized,
+ J: IntoIterator<Item = Self::Item>,
+ F: FnMut(&Self::Item, &Self::Item) -> bool
+ {
+ adaptors::merge_by_new(self, other.into_iter(), is_first)
+ }
+
+ /// Create an iterator that merges items from both this and the specified
+ /// iterator in ascending order.
+ ///
+ /// It chooses whether to pair elements based on the `Ordering` returned by the
+ /// specified compare function. At any point, inspecting the tip of the
+ /// iterators `I` and `J` as items `i` of type `I::Item` and `j` of type
+ /// `J::Item` respectively, the resulting iterator will:
+ ///
+ /// - Emit `EitherOrBoth::Left(i)` when `i < j`,
+ /// and remove `i` from its source iterator
+ /// - Emit `EitherOrBoth::Right(j)` when `i > j`,
+ /// and remove `j` from its source iterator
+ /// - Emit `EitherOrBoth::Both(i, j)` when `i == j`,
+ /// and remove both `i` and `j` from their respective source iterators
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::EitherOrBoth::{Left, Right, Both};
+ ///
+ /// let multiples_of_2 = (0..10).step(2);
+ /// let multiples_of_3 = (0..10).step(3);
+ ///
+ /// itertools::assert_equal(
+ /// multiples_of_2.merge_join_by(multiples_of_3, |i, j| i.cmp(j)),
+ /// vec![Both(0, 0), Left(2), Right(3), Left(4), Both(6, 6), Left(8), Right(9)]
+ /// );
+ /// ```
+ #[inline]
+ fn merge_join_by<J, F>(self, other: J, cmp_fn: F) -> MergeJoinBy<Self, J::IntoIter, F>
+ where J: IntoIterator,
+ F: FnMut(&Self::Item, &J::Item) -> std::cmp::Ordering,
+ Self: Sized
+ {
+ merge_join_by(self, other, cmp_fn)
+ }
+
+ /// Return an iterator adaptor that flattens an iterator of iterators by
+ /// merging them in ascending order.
+ ///
+ /// If all base iterators are sorted (ascending), the result is sorted.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a = (0..6).step(3);
+ /// let b = (1..6).step(3);
+ /// let c = (2..6).step(3);
+ /// let it = vec![a, b, c].into_iter().kmerge();
+ /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 5]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn kmerge(self) -> KMerge<<Self::Item as IntoIterator>::IntoIter>
+ where Self: Sized,
+ Self::Item: IntoIterator,
+ <Self::Item as IntoIterator>::Item: PartialOrd,
+ {
+ kmerge(self)
+ }
+
+ /// Return an iterator adaptor that flattens an iterator of iterators by
+ /// merging them according to the given closure.
+ ///
+ /// The closure `first` is called with two elements *a*, *b* and should
+ /// return `true` if *a* is ordered before *b*.
+ ///
+ /// If all base iterators are sorted according to `first`, the result is
+ /// sorted.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a = vec![-1f64, 2., 3., -5., 6., -7.];
+ /// let b = vec![0., 2., -4.];
+ /// let mut it = vec![a, b].into_iter().kmerge_by(|a, b| a.abs() < b.abs());
+ /// assert_eq!(it.next(), Some(0.));
+ /// assert_eq!(it.last(), Some(-7.));
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn kmerge_by<F>(self, first: F)
+ -> KMergeBy<<Self::Item as IntoIterator>::IntoIter, F>
+ where Self: Sized,
+ Self::Item: IntoIterator,
+ F: FnMut(&<Self::Item as IntoIterator>::Item,
+ &<Self::Item as IntoIterator>::Item) -> bool
+ {
+ kmerge_by(self, first)
+ }
+
+ /// Return an iterator adaptor that iterates over the cartesian product of
+ /// the element sets of two iterators `self` and `J`.
+ ///
+ /// Iterator element type is `(Self::Item, J::Item)`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (0..2).cartesian_product("αβ".chars());
+ /// itertools::assert_equal(it, vec![(0, 'α'), (0, 'β'), (1, 'α'), (1, 'β')]);
+ /// ```
+ fn cartesian_product<J>(self, other: J) -> Product<Self, J::IntoIter>
+ where Self: Sized,
+ Self::Item: Clone,
+ J: IntoIterator,
+ J::IntoIter: Clone
+ {
+ adaptors::cartesian_product(self, other.into_iter())
+ }
+
+ /// Return an iterator adaptor that iterates over the cartesian product of
+ /// all subiterators returned by meta-iterator `self`.
+ ///
+ /// All provided iterators must yield the same `Item` type. To generate
+ /// the product of iterators yielding multiple types, use the
+ /// [`iproduct`] macro instead.
+ ///
+ ///
+ /// The iterator element type is `Vec<T>`, where `T` is the iterator element
+ /// of the subiterators.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// let mut multi_prod = (0..3).map(|i| (i * 2)..(i * 2 + 2))
+ /// .multi_cartesian_product();
+ /// assert_eq!(multi_prod.next(), Some(vec![0, 2, 4]));
+ /// assert_eq!(multi_prod.next(), Some(vec![0, 2, 5]));
+ /// assert_eq!(multi_prod.next(), Some(vec![0, 3, 4]));
+ /// assert_eq!(multi_prod.next(), Some(vec![0, 3, 5]));
+ /// assert_eq!(multi_prod.next(), Some(vec![1, 2, 4]));
+ /// assert_eq!(multi_prod.next(), Some(vec![1, 2, 5]));
+ /// assert_eq!(multi_prod.next(), Some(vec![1, 3, 4]));
+ /// assert_eq!(multi_prod.next(), Some(vec![1, 3, 5]));
+ /// assert_eq!(multi_prod.next(), None);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn multi_cartesian_product(self) -> MultiProduct<<Self::Item as IntoIterator>::IntoIter>
+ where Self: Sized,
+ Self::Item: IntoIterator,
+ <Self::Item as IntoIterator>::IntoIter: Clone,
+ <Self::Item as IntoIterator>::Item: Clone
+ {
+ adaptors::multi_cartesian_product(self)
+ }
+
+ /// Return an iterator adaptor that uses the passed-in closure to
+ /// optionally merge together consecutive elements.
+ ///
+ /// The closure `f` is passed two elements, `previous` and `current` and may
+ /// return either (1) `Ok(combined)` to merge the two values or
+ /// (2) `Err((previous', current'))` to indicate they can't be merged.
+ /// In (2), the value `previous'` is emitted by the iterator.
+ /// Either (1) `combined` or (2) `current'` becomes the previous value
+ /// when coalesce continues with the next pair of elements to merge. The
+ /// value that remains at the end is also emitted by the iterator.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sum same-sign runs together
+ /// let data = vec![-1., -2., -3., 3., 1., 0., -1.];
+ /// itertools::assert_equal(data.into_iter().coalesce(|x, y|
+ /// if (x >= 0.) == (y >= 0.) {
+ /// Ok(x + y)
+ /// } else {
+ /// Err((x, y))
+ /// }),
+ /// vec![-6., 4., -1.]);
+ /// ```
+ fn coalesce<F>(self, f: F) -> Coalesce<Self, F>
+ where Self: Sized,
+ F: FnMut(Self::Item, Self::Item)
+ -> Result<Self::Item, (Self::Item, Self::Item)>
+ {
+ adaptors::coalesce(self, f)
+ }
+
+ /// Remove duplicates from sections of consecutive identical elements.
+ /// If the iterator is sorted, all elements will be unique.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![1., 1., 2., 3., 3., 2., 2.];
+ /// itertools::assert_equal(data.into_iter().dedup(),
+ /// vec![1., 2., 3., 2.]);
+ /// ```
+ fn dedup(self) -> Dedup<Self>
+ where Self: Sized,
+ Self::Item: PartialEq,
+ {
+ adaptors::dedup(self)
+ }
+
+ /// Remove duplicates from sections of consecutive identical elements,
+ /// determining equality using a comparison function.
+ /// If the iterator is sorted, all elements will be unique.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![(0, 1.), (1, 1.), (0, 2.), (0, 3.), (1, 3.), (1, 2.), (2, 2.)];
+ /// itertools::assert_equal(data.into_iter().dedup_by(|x, y| x.1 == y.1),
+ /// vec![(0, 1.), (0, 2.), (0, 3.), (1, 2.)]);
+ /// ```
+ fn dedup_by<Cmp>(self, cmp: Cmp) -> DedupBy<Self, Cmp>
+ where Self: Sized,
+ Cmp: FnMut(&Self::Item, &Self::Item)->bool,
+ {
+ adaptors::dedup_by(self, cmp)
+ }
+
+ /// Remove duplicates from sections of consecutive identical elements, while keeping a count of
+ /// how many repeated elements were present.
+ /// If the iterator is sorted, all elements will be unique.
+ ///
+ /// Iterator element type is `(usize, Self::Item)`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec!['a', 'a', 'b', 'c', 'c', 'b', 'b'];
+ /// itertools::assert_equal(data.into_iter().dedup_with_count(),
+ /// vec![(2, 'a'), (1, 'b'), (2, 'c'), (2, 'b')]);
+ /// ```
+ fn dedup_with_count(self) -> DedupWithCount<Self>
+ where
+ Self: Sized,
+ {
+ adaptors::dedup_with_count(self)
+ }
+
+ /// Remove duplicates from sections of consecutive identical elements, while keeping a count of
+ /// how many repeated elements were present.
+ /// This will determine equality using a comparison function.
+ /// If the iterator is sorted, all elements will be unique.
+ ///
+ /// Iterator element type is `(usize, Self::Item)`.
+ ///
+ /// This iterator is *fused*.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![(0, 'a'), (1, 'a'), (0, 'b'), (0, 'c'), (1, 'c'), (1, 'b'), (2, 'b')];
+ /// itertools::assert_equal(data.into_iter().dedup_by_with_count(|x, y| x.1 == y.1),
+ /// vec![(2, (0, 'a')), (1, (0, 'b')), (2, (0, 'c')), (2, (1, 'b'))]);
+ /// ```
+ fn dedup_by_with_count<Cmp>(self, cmp: Cmp) -> DedupByWithCount<Self, Cmp>
+ where
+ Self: Sized,
+ Cmp: FnMut(&Self::Item, &Self::Item) -> bool,
+ {
+ adaptors::dedup_by_with_count(self, cmp)
+ }
+
+ /// Return an iterator adaptor that produces elements that appear more than once during the
+ /// iteration. Duplicates are detected using hash and equality.
+ ///
+ /// The iterator is stable, returning the duplicate items in the order in which they occur in
+ /// the adapted iterator. Each duplicate item is returned exactly once. If an item appears more
+ /// than twice, the second item is the item retained and the rest are discarded.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![10, 20, 30, 20, 40, 10, 50];
+ /// itertools::assert_equal(data.into_iter().duplicates(),
+ /// vec![20, 10]);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn duplicates(self) -> Duplicates<Self>
+ where Self: Sized,
+ Self::Item: Eq + Hash
+ {
+ duplicates_impl::duplicates(self)
+ }
+
+ /// Return an iterator adaptor that produces elements that appear more than once during the
+ /// iteration. Duplicates are detected using hash and equality.
+ ///
+ /// Duplicates are detected by comparing the key they map to with the keying function `f` by
+ /// hash and equality. The keys are stored in a hash map in the iterator.
+ ///
+ /// The iterator is stable, returning the duplicate items in the order in which they occur in
+ /// the adapted iterator. Each duplicate item is returned exactly once. If an item appears more
+ /// than twice, the second item is the item retained and the rest are discarded.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec!["a", "bb", "aa", "c", "ccc"];
+ /// itertools::assert_equal(data.into_iter().duplicates_by(|s| s.len()),
+ /// vec!["aa", "c"]);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn duplicates_by<V, F>(self, f: F) -> DuplicatesBy<Self, V, F>
+ where Self: Sized,
+ V: Eq + Hash,
+ F: FnMut(&Self::Item) -> V
+ {
+ duplicates_impl::duplicates_by(self, f)
+ }
+
+ /// Return an iterator adaptor that filters out elements that have
+ /// already been produced once during the iteration. Duplicates
+ /// are detected using hash and equality.
+ ///
+ /// Clones of visited elements are stored in a hash set in the
+ /// iterator.
+ ///
+ /// The iterator is stable, returning the non-duplicate items in the order
+ /// in which they occur in the adapted iterator. In a set of duplicate
+ /// items, the first item encountered is the item retained.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![10, 20, 30, 20, 40, 10, 50];
+ /// itertools::assert_equal(data.into_iter().unique(),
+ /// vec![10, 20, 30, 40, 50]);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn unique(self) -> Unique<Self>
+ where Self: Sized,
+ Self::Item: Clone + Eq + Hash
+ {
+ unique_impl::unique(self)
+ }
+
+ /// Return an iterator adaptor that filters out elements that have
+ /// already been produced once during the iteration.
+ ///
+ /// Duplicates are detected by comparing the key they map to
+ /// with the keying function `f` by hash and equality.
+ /// The keys are stored in a hash set in the iterator.
+ ///
+ /// The iterator is stable, returning the non-duplicate items in the order
+ /// in which they occur in the adapted iterator. In a set of duplicate
+ /// items, the first item encountered is the item retained.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec!["a", "bb", "aa", "c", "ccc"];
+ /// itertools::assert_equal(data.into_iter().unique_by(|s| s.len()),
+ /// vec!["a", "bb", "ccc"]);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn unique_by<V, F>(self, f: F) -> UniqueBy<Self, V, F>
+ where Self: Sized,
+ V: Eq + Hash,
+ F: FnMut(&Self::Item) -> V
+ {
+ unique_impl::unique_by(self, f)
+ }
+
+ /// Return an iterator adaptor that borrows from this iterator and
+ /// takes items while the closure `accept` returns `true`.
+ ///
+ /// This adaptor can only be used on iterators that implement `PeekingNext`
+ /// like `.peekable()`, `put_back` and a few other collection iterators.
+ ///
+ /// The last and rejected element (first `false`) is still available when
+ /// `peeking_take_while` is done.
+ ///
+ ///
+ /// See also [`.take_while_ref()`](Itertools::take_while_ref)
+ /// which is a similar adaptor.
+ fn peeking_take_while<F>(&mut self, accept: F) -> PeekingTakeWhile<Self, F>
+ where Self: Sized + PeekingNext,
+ F: FnMut(&Self::Item) -> bool,
+ {
+ peeking_take_while::peeking_take_while(self, accept)
+ }
+
+ /// Return an iterator adaptor that borrows from a `Clone`-able iterator
+ /// to only pick off elements while the predicate `accept` returns `true`.
+ ///
+ /// It uses the `Clone` trait to restore the original iterator so that the
+ /// last and rejected element (first `false`) is still available when
+ /// `take_while_ref` is done.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut hexadecimals = "0123456789abcdef".chars();
+ ///
+ /// let decimals = hexadecimals.take_while_ref(|c| c.is_numeric())
+ /// .collect::<String>();
+ /// assert_eq!(decimals, "0123456789");
+ /// assert_eq!(hexadecimals.next(), Some('a'));
+ ///
+ /// ```
+ fn take_while_ref<F>(&mut self, accept: F) -> TakeWhileRef<Self, F>
+ where Self: Clone,
+ F: FnMut(&Self::Item) -> bool
+ {
+ adaptors::take_while_ref(self, accept)
+ }
+
+ /// Return an iterator adaptor that filters `Option<A>` iterator elements
+ /// and produces `A`. Stops on the first `None` encountered.
+ ///
+ /// Iterator element type is `A`, the unwrapped element.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // List all hexadecimal digits
+ /// itertools::assert_equal(
+ /// (0..).map(|i| std::char::from_digit(i, 16)).while_some(),
+ /// "0123456789abcdef".chars());
+ ///
+ /// ```
+ fn while_some<A>(self) -> WhileSome<Self>
+ where Self: Sized + Iterator<Item = Option<A>>
+ {
+ adaptors::while_some(self)
+ }
+
+ /// Return an iterator adaptor that iterates over the combinations of the
+ /// elements from an iterator.
+ ///
+ /// Iterator element can be any homogeneous tuple of type `Self::Item` with
+ /// size up to 12.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut v = Vec::new();
+ /// for (a, b) in (1..5).tuple_combinations() {
+ /// v.push((a, b));
+ /// }
+ /// assert_eq!(v, vec![(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]);
+ ///
+ /// let mut it = (1..5).tuple_combinations();
+ /// assert_eq!(Some((1, 2, 3)), it.next());
+ /// assert_eq!(Some((1, 2, 4)), it.next());
+ /// assert_eq!(Some((1, 3, 4)), it.next());
+ /// assert_eq!(Some((2, 3, 4)), it.next());
+ /// assert_eq!(None, it.next());
+ ///
+ /// // this requires a type hint
+ /// let it = (1..5).tuple_combinations::<(_, _, _)>();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]);
+ ///
+ /// // you can also specify the complete type
+ /// use itertools::TupleCombinations;
+ /// use std::ops::Range;
+ ///
+ /// let it: TupleCombinations<Range<u32>, (u32, u32, u32)> = (1..5).tuple_combinations();
+ /// itertools::assert_equal(it, vec![(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]);
+ /// ```
+ fn tuple_combinations<T>(self) -> TupleCombinations<Self, T>
+ where Self: Sized + Clone,
+ Self::Item: Clone,
+ T: adaptors::HasCombination<Self>,
+ {
+ adaptors::tuple_combinations(self)
+ }
+
+ /// Return an iterator adaptor that iterates over the `k`-length combinations of
+ /// the elements from an iterator.
+ ///
+ /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new Vec per iteration,
+ /// and clones the iterator elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (1..5).combinations(3);
+ /// itertools::assert_equal(it, vec![
+ /// vec![1, 2, 3],
+ /// vec![1, 2, 4],
+ /// vec![1, 3, 4],
+ /// vec![2, 3, 4],
+ /// ]);
+ /// ```
+ ///
+ /// Note: Combinations does not take into account the equality of the iterated values.
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = vec![1, 2, 2].into_iter().combinations(2);
+ /// itertools::assert_equal(it, vec![
+ /// vec![1, 2], // Note: these are the same
+ /// vec![1, 2], // Note: these are the same
+ /// vec![2, 2],
+ /// ]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn combinations(self, k: usize) -> Combinations<Self>
+ where Self: Sized,
+ Self::Item: Clone
+ {
+ combinations::combinations(self, k)
+ }
+
+ /// Return an iterator that iterates over the `k`-length combinations of
+ /// the elements from an iterator, with replacement.
+ ///
+ /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new Vec per iteration,
+ /// and clones the iterator elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (1..4).combinations_with_replacement(2);
+ /// itertools::assert_equal(it, vec![
+ /// vec![1, 1],
+ /// vec![1, 2],
+ /// vec![1, 3],
+ /// vec![2, 2],
+ /// vec![2, 3],
+ /// vec![3, 3],
+ /// ]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn combinations_with_replacement(self, k: usize) -> CombinationsWithReplacement<Self>
+ where
+ Self: Sized,
+ Self::Item: Clone,
+ {
+ combinations_with_replacement::combinations_with_replacement(self, k)
+ }
+
+ /// Return an iterator adaptor that iterates over all k-permutations of the
+ /// elements from an iterator.
+ ///
+ /// Iterator element type is `Vec<Self::Item>` with length `k`. The iterator
+ /// produces a new Vec per iteration, and clones the iterator elements.
+ ///
+ /// If `k` is greater than the length of the input iterator, the resultant
+ /// iterator adaptor will be empty.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let perms = (5..8).permutations(2);
+ /// itertools::assert_equal(perms, vec![
+ /// vec![5, 6],
+ /// vec![5, 7],
+ /// vec![6, 5],
+ /// vec![6, 7],
+ /// vec![7, 5],
+ /// vec![7, 6],
+ /// ]);
+ /// ```
+ ///
+ /// Note: Permutations does not take into account the equality of the iterated values.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = vec![2, 2].into_iter().permutations(2);
+ /// itertools::assert_equal(it, vec![
+ /// vec![2, 2], // Note: these are the same
+ /// vec![2, 2], // Note: these are the same
+ /// ]);
+ /// ```
+ ///
+ /// Note: The source iterator is collected lazily, and will not be
+ /// re-iterated if the permutations adaptor is completed and re-iterated.
+ #[cfg(feature = "use_alloc")]
+ fn permutations(self, k: usize) -> Permutations<Self>
+ where Self: Sized,
+ Self::Item: Clone
+ {
+ permutations::permutations(self, k)
+ }
+
+ /// Return an iterator that iterates through the powerset of the elements from an
+ /// iterator.
+ ///
+ /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new `Vec`
+ /// per iteration, and clones the iterator elements.
+ ///
+ /// The powerset of a set contains all subsets including the empty set and the full
+ /// input set. A powerset has length _2^n_ where _n_ is the length of the input
+ /// set.
+ ///
+ /// Each `Vec` produced by this iterator represents a subset of the elements
+ /// produced by the source iterator.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let sets = (1..4).powerset().collect::<Vec<_>>();
+ /// itertools::assert_equal(sets, vec![
+ /// vec![],
+ /// vec![1],
+ /// vec![2],
+ /// vec![3],
+ /// vec![1, 2],
+ /// vec![1, 3],
+ /// vec![2, 3],
+ /// vec![1, 2, 3],
+ /// ]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn powerset(self) -> Powerset<Self>
+ where Self: Sized,
+ Self::Item: Clone,
+ {
+ powerset::powerset(self)
+ }
+
+ /// Return an iterator adaptor that pads the sequence to a minimum length of
+ /// `min` by filling missing elements using a closure `f`.
+ ///
+ /// Iterator element type is `Self::Item`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let it = (0..5).pad_using(10, |i| 2*i);
+ /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 10, 12, 14, 16, 18]);
+ ///
+ /// let it = (0..10).pad_using(5, |i| 2*i);
+ /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+ ///
+ /// let it = (0..5).pad_using(10, |i| 2*i).rev();
+ /// itertools::assert_equal(it, vec![18, 16, 14, 12, 10, 4, 3, 2, 1, 0]);
+ /// ```
+ fn pad_using<F>(self, min: usize, f: F) -> PadUsing<Self, F>
+ where Self: Sized,
+ F: FnMut(usize) -> Self::Item
+ {
+ pad_tail::pad_using(self, min, f)
+ }
+
+ /// Return an iterator adaptor that wraps each element in a `Position` to
+ /// ease special-case handling of the first or last elements.
+ ///
+ /// Iterator element type is
+ /// [`Position<Self::Item>`](Position)
+ ///
+ /// ```
+ /// use itertools::{Itertools, Position};
+ ///
+ /// let it = (0..4).with_position();
+ /// itertools::assert_equal(it,
+ /// vec![Position::First(0),
+ /// Position::Middle(1),
+ /// Position::Middle(2),
+ /// Position::Last(3)]);
+ ///
+ /// let it = (0..1).with_position();
+ /// itertools::assert_equal(it, vec![Position::Only(0)]);
+ /// ```
+ fn with_position(self) -> WithPosition<Self>
+ where Self: Sized,
+ {
+ with_position::with_position(self)
+ }
+
+ /// Return an iterator adaptor that yields the indices of all elements
+ /// satisfying a predicate, counted from the start of the iterator.
+ ///
+ /// Equivalent to `iter.enumerate().filter(|(_, v)| predicate(v)).map(|(i, _)| i)`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![1, 2, 3, 3, 4, 6, 7, 9];
+ /// itertools::assert_equal(data.iter().positions(|v| v % 2 == 0), vec![1, 4, 5]);
+ ///
+ /// itertools::assert_equal(data.iter().positions(|v| v % 2 == 1).rev(), vec![7, 6, 3, 2, 0]);
+ /// ```
+ fn positions<P>(self, predicate: P) -> Positions<Self, P>
+ where Self: Sized,
+ P: FnMut(Self::Item) -> bool,
+ {
+ adaptors::positions(self, predicate)
+ }
+
+ /// Return an iterator adaptor that applies a mutating function
+ /// to each element before yielding it.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![vec![1], vec![3, 2, 1]];
+ /// let it = input.into_iter().update(|mut v| v.push(0));
+ /// itertools::assert_equal(it, vec![vec![1, 0], vec![3, 2, 1, 0]]);
+ /// ```
+ fn update<F>(self, updater: F) -> Update<Self, F>
+ where Self: Sized,
+ F: FnMut(&mut Self::Item),
+ {
+ adaptors::update(self, updater)
+ }
+
+ // non-adaptor methods
+ /// Advances the iterator and returns the next items grouped in a tuple of
+ /// a specific size (up to 12).
+ ///
+ /// If there are enough elements to be grouped in a tuple, then the tuple is
+ /// returned inside `Some`, otherwise `None` is returned.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut iter = 1..5;
+ ///
+ /// assert_eq!(Some((1, 2)), iter.next_tuple());
+ /// ```
+ fn next_tuple<T>(&mut self) -> Option<T>
+ where Self: Sized + Iterator<Item = T::Item>,
+ T: traits::HomogeneousTuple
+ {
+ T::collect_from_iter_no_buf(self)
+ }
+
+ /// Collects all items from the iterator into a tuple of a specific size
+ /// (up to 12).
+ ///
+ /// If the number of elements inside the iterator is **exactly** equal to
+ /// the tuple size, then the tuple is returned inside `Some`, otherwise
+ /// `None` is returned.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let iter = 1..3;
+ ///
+ /// if let Some((x, y)) = iter.collect_tuple() {
+ /// assert_eq!((x, y), (1, 2))
+ /// } else {
+ /// panic!("Expected two elements")
+ /// }
+ /// ```
+ fn collect_tuple<T>(mut self) -> Option<T>
+ where Self: Sized + Iterator<Item = T::Item>,
+ T: traits::HomogeneousTuple
+ {
+ match self.next_tuple() {
+ elt @ Some(_) => match self.next() {
+ Some(_) => None,
+ None => elt,
+ },
+ _ => None
+ }
+ }
+
+
+ /// Find the position and value of the first element satisfying a predicate.
+ ///
+ /// The iterator is not advanced past the first element found.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let text = "Hα";
+ /// assert_eq!(text.chars().find_position(|ch| ch.is_lowercase()), Some((1, 'α')));
+ /// ```
+ fn find_position<P>(&mut self, mut pred: P) -> Option<(usize, Self::Item)>
+ where P: FnMut(&Self::Item) -> bool
+ {
+ for (index, elt) in self.enumerate() {
+ if pred(&elt) {
+ return Some((index, elt));
+ }
+ }
+ None
+ }
+ /// Find the value of the first element satisfying a predicate or return the last element, if any.
+ ///
+ /// The iterator is not advanced past the first element found.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let numbers = [1, 2, 3, 4];
+ /// assert_eq!(numbers.iter().find_or_last(|&&x| x > 5), Some(&4));
+ /// assert_eq!(numbers.iter().find_or_last(|&&x| x > 2), Some(&3));
+ /// assert_eq!(std::iter::empty::<i32>().find_or_last(|&x| x > 5), None);
+ /// ```
+ fn find_or_last<P>(mut self, mut predicate: P) -> Option<Self::Item>
+ where Self: Sized,
+ P: FnMut(&Self::Item) -> bool,
+ {
+ let mut prev = None;
+ self.find_map(|x| if predicate(&x) { Some(x) } else { prev = Some(x); None })
+ .or(prev)
+ }
+ /// Find the value of the first element satisfying a predicate or return the first element, if any.
+ ///
+ /// The iterator is not advanced past the first element found.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let numbers = [1, 2, 3, 4];
+ /// assert_eq!(numbers.iter().find_or_first(|&&x| x > 5), Some(&1));
+ /// assert_eq!(numbers.iter().find_or_first(|&&x| x > 2), Some(&3));
+ /// assert_eq!(std::iter::empty::<i32>().find_or_first(|&x| x > 5), None);
+ /// ```
+ fn find_or_first<P>(mut self, mut predicate: P) -> Option<Self::Item>
+ where Self: Sized,
+ P: FnMut(&Self::Item) -> bool,
+ {
+ let first = self.next()?;
+ Some(if predicate(&first) {
+ first
+ } else {
+ self.find(|x| predicate(x)).unwrap_or(first)
+ })
+ }
+ /// Returns `true` if the given item is present in this iterator.
+ ///
+ /// This method is short-circuiting. If the given item is present in this
+ /// iterator, this method will consume the iterator up-to-and-including
+ /// the item. If the given item is not present in this iterator, the
+ /// iterator will be exhausted.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// #[derive(PartialEq, Debug)]
+ /// enum Enum { A, B, C, D, E, }
+ ///
+ /// let mut iter = vec![Enum::A, Enum::B, Enum::C, Enum::D].into_iter();
+ ///
+ /// // search `iter` for `B`
+ /// assert_eq!(iter.contains(&Enum::B), true);
+ /// // `B` was found, so the iterator now rests at the item after `B` (i.e, `C`).
+ /// assert_eq!(iter.next(), Some(Enum::C));
+ ///
+ /// // search `iter` for `E`
+ /// assert_eq!(iter.contains(&Enum::E), false);
+ /// // `E` wasn't found, so `iter` is now exhausted
+ /// assert_eq!(iter.next(), None);
+ /// ```
+ fn contains<Q>(&mut self, query: &Q) -> bool
+ where
+ Self: Sized,
+ Self::Item: Borrow<Q>,
+ Q: PartialEq,
+ {
+ self.any(|x| x.borrow() == query)
+ }
+
+ /// Check whether all elements compare equal.
+ ///
+ /// Empty iterators are considered to have equal elements:
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![1, 1, 1, 2, 2, 3, 3, 3, 4, 5, 5];
+ /// assert!(!data.iter().all_equal());
+ /// assert!(data[0..3].iter().all_equal());
+ /// assert!(data[3..5].iter().all_equal());
+ /// assert!(data[5..8].iter().all_equal());
+ ///
+ /// let data : Option<usize> = None;
+ /// assert!(data.into_iter().all_equal());
+ /// ```
+ fn all_equal(&mut self) -> bool
+ where Self: Sized,
+ Self::Item: PartialEq,
+ {
+ match self.next() {
+ None => true,
+ Some(a) => self.all(|x| a == x),
+ }
+ }
+
+ /// Check whether all elements are unique (non equal).
+ ///
+ /// Empty iterators are considered to have unique elements:
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![1, 2, 3, 4, 1, 5];
+ /// assert!(!data.iter().all_unique());
+ /// assert!(data[0..4].iter().all_unique());
+ /// assert!(data[1..6].iter().all_unique());
+ ///
+ /// let data : Option<usize> = None;
+ /// assert!(data.into_iter().all_unique());
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn all_unique(&mut self) -> bool
+ where Self: Sized,
+ Self::Item: Eq + Hash
+ {
+ let mut used = HashSet::new();
+ self.all(move |elt| used.insert(elt))
+ }
+
+ /// Consume the first `n` elements from the iterator eagerly,
+ /// and return the same iterator again.
+ ///
+ /// It works similarly to *.skip(* `n` *)* except it is eager and
+ /// preserves the iterator type.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut iter = "αβγ".chars().dropping(2);
+ /// itertools::assert_equal(iter, "γ".chars());
+ /// ```
+ ///
+ /// *Fusing notes: if the iterator is exhausted by dropping,
+ /// the result of calling `.next()` again depends on the iterator implementation.*
+ fn dropping(mut self, n: usize) -> Self
+ where Self: Sized
+ {
+ if n > 0 {
+ self.nth(n - 1);
+ }
+ self
+ }
+
+ /// Consume the last `n` elements from the iterator eagerly,
+ /// and return the same iterator again.
+ ///
+ /// This is only possible on double ended iterators. `n` may be
+ /// larger than the number of elements.
+ ///
+ /// Note: This method is eager, dropping the back elements immediately and
+ /// preserves the iterator type.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let init = vec![0, 3, 6, 9].into_iter().dropping_back(1);
+ /// itertools::assert_equal(init, vec![0, 3, 6]);
+ /// ```
+ fn dropping_back(mut self, n: usize) -> Self
+ where Self: Sized,
+ Self: DoubleEndedIterator
+ {
+ if n > 0 {
+ (&mut self).rev().nth(n - 1);
+ }
+ self
+ }
+
+ /// Run the closure `f` eagerly on each element of the iterator.
+ ///
+ /// Consumes the iterator until its end.
+ ///
+ /// ```
+ /// use std::sync::mpsc::channel;
+ /// use itertools::Itertools;
+ ///
+ /// let (tx, rx) = channel();
+ ///
+ /// // use .foreach() to apply a function to each value -- sending it
+ /// (0..5).map(|x| x * 2 + 1).foreach(|x| { tx.send(x).unwrap(); } );
+ ///
+ /// drop(tx);
+ ///
+ /// itertools::assert_equal(rx.iter(), vec![1, 3, 5, 7, 9]);
+ /// ```
+ #[deprecated(note="Use .for_each() instead", since="0.8.0")]
+ fn foreach<F>(self, f: F)
+ where F: FnMut(Self::Item),
+ Self: Sized,
+ {
+ self.for_each(f);
+ }
+
+ /// Combine all an iterator's elements into one element by using [`Extend`].
+ ///
+ /// This combinator will extend the first item with each of the rest of the
+ /// items of the iterator. If the iterator is empty, the default value of
+ /// `I::Item` is returned.
+ ///
+ /// ```rust
+ /// use itertools::Itertools;
+ ///
+ /// let input = vec![vec![1], vec![2, 3], vec![4, 5, 6]];
+ /// assert_eq!(input.into_iter().concat(),
+ /// vec![1, 2, 3, 4, 5, 6]);
+ /// ```
+ fn concat(self) -> Self::Item
+ where Self: Sized,
+ Self::Item: Extend<<<Self as Iterator>::Item as IntoIterator>::Item> + IntoIterator + Default
+ {
+ concat(self)
+ }
+
+ /// `.collect_vec()` is simply a type specialization of [`Iterator::collect`],
+ /// for convenience.
+ #[cfg(feature = "use_alloc")]
+ fn collect_vec(self) -> Vec<Self::Item>
+ where Self: Sized
+ {
+ self.collect()
+ }
+
+ /// `.try_collect()` is more convenient way of writing
+ /// `.collect::<Result<_, _>>()`
+ ///
+ /// # Example
+ ///
+ /// ```
+ /// use std::{fs, io};
+ /// use itertools::Itertools;
+ ///
+ /// fn process_dir_entries(entries: &[fs::DirEntry]) {
+ /// // ...
+ /// }
+ ///
+ /// fn do_stuff() -> std::io::Result<()> {
+ /// let entries: Vec<_> = fs::read_dir(".")?.try_collect()?;
+ /// process_dir_entries(&entries);
+ ///
+ /// Ok(())
+ /// }
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn try_collect<T, U, E>(self) -> Result<U, E>
+ where
+ Self: Sized + Iterator<Item = Result<T, E>>,
+ Result<U, E>: FromIterator<Result<T, E>>,
+ {
+ self.collect()
+ }
+
+ /// Assign to each reference in `self` from the `from` iterator,
+ /// stopping at the shortest of the two iterators.
+ ///
+ /// The `from` iterator is queried for its next element before the `self`
+ /// iterator, and if either is exhausted the method is done.
+ ///
+ /// Return the number of elements written.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut xs = [0; 4];
+ /// xs.iter_mut().set_from(1..);
+ /// assert_eq!(xs, [1, 2, 3, 4]);
+ /// ```
+ #[inline]
+ fn set_from<'a, A: 'a, J>(&mut self, from: J) -> usize
+ where Self: Iterator<Item = &'a mut A>,
+ J: IntoIterator<Item = A>
+ {
+ let mut count = 0;
+ for elt in from {
+ match self.next() {
+ None => break,
+ Some(ptr) => *ptr = elt,
+ }
+ count += 1;
+ }
+ count
+ }
+
+ /// Combine all iterator elements into one String, separated by `sep`.
+ ///
+ /// Use the `Display` implementation of each element.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// assert_eq!(["a", "b", "c"].iter().join(", "), "a, b, c");
+ /// assert_eq!([1, 2, 3].iter().join(", "), "1, 2, 3");
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn join(&mut self, sep: &str) -> String
+ where Self::Item: std::fmt::Display
+ {
+ match self.next() {
+ None => String::new(),
+ Some(first_elt) => {
+ // estimate lower bound of capacity needed
+ let (lower, _) = self.size_hint();
+ let mut result = String::with_capacity(sep.len() * lower);
+ write!(&mut result, "{}", first_elt).unwrap();
+ self.for_each(|elt| {
+ result.push_str(sep);
+ write!(&mut result, "{}", elt).unwrap();
+ });
+ result
+ }
+ }
+ }
+
+ /// Format all iterator elements, separated by `sep`.
+ ///
+ /// All elements are formatted (any formatting trait)
+ /// with `sep` inserted between each element.
+ ///
+ /// **Panics** if the formatter helper is formatted more than once.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = [1.1, 2.71828, -3.];
+ /// assert_eq!(
+ /// format!("{:.2}", data.iter().format(", ")),
+ /// "1.10, 2.72, -3.00");
+ /// ```
+ fn format(self, sep: &str) -> Format<Self>
+ where Self: Sized,
+ {
+ format::new_format_default(self, sep)
+ }
+
+ /// Format all iterator elements, separated by `sep`.
+ ///
+ /// This is a customizable version of [`.format()`](Itertools::format).
+ ///
+ /// The supplied closure `format` is called once per iterator element,
+ /// with two arguments: the element and a callback that takes a
+ /// `&Display` value, i.e. any reference to type that implements `Display`.
+ ///
+ /// Using `&format_args!(...)` is the most versatile way to apply custom
+ /// element formatting. The callback can be called multiple times if needed.
+ ///
+ /// **Panics** if the formatter helper is formatted more than once.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = [1.1, 2.71828, -3.];
+ /// let data_formatter = data.iter().format_with(", ", |elt, f| f(&format_args!("{:.2}", elt)));
+ /// assert_eq!(format!("{}", data_formatter),
+ /// "1.10, 2.72, -3.00");
+ ///
+ /// // .format_with() is recursively composable
+ /// let matrix = [[1., 2., 3.],
+ /// [4., 5., 6.]];
+ /// let matrix_formatter = matrix.iter().format_with("\n", |row, f| {
+ /// f(&row.iter().format_with(", ", |elt, g| g(&elt)))
+ /// });
+ /// assert_eq!(format!("{}", matrix_formatter),
+ /// "1, 2, 3\n4, 5, 6");
+ ///
+ ///
+ /// ```
+ fn format_with<F>(self, sep: &str, format: F) -> FormatWith<Self, F>
+ where Self: Sized,
+ F: FnMut(Self::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result,
+ {
+ format::new_format(self, sep, format)
+ }
+
+ /// See [`.fold_ok()`](Itertools::fold_ok).
+ #[deprecated(note="Use .fold_ok() instead", since="0.10.0")]
+ fn fold_results<A, E, B, F>(&mut self, start: B, f: F) -> Result<B, E>
+ where Self: Iterator<Item = Result<A, E>>,
+ F: FnMut(B, A) -> B
+ {
+ self.fold_ok(start, f)
+ }
+
+ /// Fold `Result` values from an iterator.
+ ///
+ /// Only `Ok` values are folded. If no error is encountered, the folded
+ /// value is returned inside `Ok`. Otherwise, the operation terminates
+ /// and returns the first `Err` value it encounters. No iterator elements are
+ /// consumed after the first error.
+ ///
+ /// The first accumulator value is the `start` parameter.
+ /// Each iteration passes the accumulator value and the next value inside `Ok`
+ /// to the fold function `f` and its return value becomes the new accumulator value.
+ ///
+ /// For example the sequence *Ok(1), Ok(2), Ok(3)* will result in a
+ /// computation like this:
+ ///
+ /// ```ignore
+ /// let mut accum = start;
+ /// accum = f(accum, 1);
+ /// accum = f(accum, 2);
+ /// accum = f(accum, 3);
+ /// ```
+ ///
+ /// With a `start` value of 0 and an addition as folding function,
+ /// this effectively results in *((0 + 1) + 2) + 3*
+ ///
+ /// ```
+ /// use std::ops::Add;
+ /// use itertools::Itertools;
+ ///
+ /// let values = [1, 2, -2, -1, 2, 1];
+ /// assert_eq!(
+ /// values.iter()
+ /// .map(Ok::<_, ()>)
+ /// .fold_ok(0, Add::add),
+ /// Ok(3)
+ /// );
+ /// assert!(
+ /// values.iter()
+ /// .map(|&x| if x >= 0 { Ok(x) } else { Err("Negative number") })
+ /// .fold_ok(0, Add::add)
+ /// .is_err()
+ /// );
+ /// ```
+ fn fold_ok<A, E, B, F>(&mut self, mut start: B, mut f: F) -> Result<B, E>
+ where Self: Iterator<Item = Result<A, E>>,
+ F: FnMut(B, A) -> B
+ {
+ for elt in self {
+ match elt {
+ Ok(v) => start = f(start, v),
+ Err(u) => return Err(u),
+ }
+ }
+ Ok(start)
+ }
+
+ /// Fold `Option` values from an iterator.
+ ///
+ /// Only `Some` values are folded. If no `None` is encountered, the folded
+ /// value is returned inside `Some`. Otherwise, the operation terminates
+ /// and returns `None`. No iterator elements are consumed after the `None`.
+ ///
+ /// This is the `Option` equivalent to [`fold_ok`](Itertools::fold_ok).
+ ///
+ /// ```
+ /// use std::ops::Add;
+ /// use itertools::Itertools;
+ ///
+ /// let mut values = vec![Some(1), Some(2), Some(-2)].into_iter();
+ /// assert_eq!(values.fold_options(5, Add::add), Some(5 + 1 + 2 - 2));
+ ///
+ /// let mut more_values = vec![Some(2), None, Some(0)].into_iter();
+ /// assert!(more_values.fold_options(0, Add::add).is_none());
+ /// assert_eq!(more_values.next().unwrap(), Some(0));
+ /// ```
+ fn fold_options<A, B, F>(&mut self, mut start: B, mut f: F) -> Option<B>
+ where Self: Iterator<Item = Option<A>>,
+ F: FnMut(B, A) -> B
+ {
+ for elt in self {
+ match elt {
+ Some(v) => start = f(start, v),
+ None => return None,
+ }
+ }
+ Some(start)
+ }
+
+ /// Accumulator of the elements in the iterator.
+ ///
+ /// Like `.fold()`, without a base case. If the iterator is
+ /// empty, return `None`. With just one element, return it.
+ /// Otherwise elements are accumulated in sequence using the closure `f`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// assert_eq!((0..10).fold1(|x, y| x + y).unwrap_or(0), 45);
+ /// assert_eq!((0..0).fold1(|x, y| x * y), None);
+ /// ```
+ #[deprecated(since = "0.10.2", note = "Use `Iterator::reduce` instead")]
+ fn fold1<F>(mut self, f: F) -> Option<Self::Item>
+ where F: FnMut(Self::Item, Self::Item) -> Self::Item,
+ Self: Sized,
+ {
+ self.next().map(move |x| self.fold(x, f))
+ }
+
+ /// Accumulate the elements in the iterator in a tree-like manner.
+ ///
+ /// You can think of it as, while there's more than one item, repeatedly
+ /// combining adjacent items. It does so in bottom-up-merge-sort order,
+ /// however, so that it needs only logarithmic stack space.
+ ///
+ /// This produces a call tree like the following (where the calls under
+ /// an item are done after reading that item):
+ ///
+ /// ```text
+ /// 1 2 3 4 5 6 7
+ /// │ │ │ │ │ │ │
+ /// └─f └─f └─f │
+ /// │ │ │ │
+ /// └───f └─f
+ /// │ │
+ /// └─────f
+ /// ```
+ ///
+ /// Which, for non-associative functions, will typically produce a different
+ /// result than the linear call tree used by [`Iterator::reduce`]:
+ ///
+ /// ```text
+ /// 1 2 3 4 5 6 7
+ /// │ │ │ │ │ │ │
+ /// └─f─f─f─f─f─f
+ /// ```
+ ///
+ /// If `f` is associative, prefer the normal [`Iterator::reduce`] instead.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // The same tree as above
+ /// let num_strings = (1..8).map(|x| x.to_string());
+ /// assert_eq!(num_strings.tree_fold1(|x, y| format!("f({}, {})", x, y)),
+ /// Some(String::from("f(f(f(1, 2), f(3, 4)), f(f(5, 6), 7))")));
+ ///
+ /// // Like fold1, an empty iterator produces None
+ /// assert_eq!((0..0).tree_fold1(|x, y| x * y), None);
+ ///
+ /// // tree_fold1 matches fold1 for associative operations...
+ /// assert_eq!((0..10).tree_fold1(|x, y| x + y),
+ /// (0..10).fold1(|x, y| x + y));
+ /// // ...but not for non-associative ones
+ /// assert_ne!((0..10).tree_fold1(|x, y| x - y),
+ /// (0..10).fold1(|x, y| x - y));
+ /// ```
+ fn tree_fold1<F>(mut self, mut f: F) -> Option<Self::Item>
+ where F: FnMut(Self::Item, Self::Item) -> Self::Item,
+ Self: Sized,
+ {
+ type State<T> = Result<T, Option<T>>;
+
+ fn inner0<T, II, FF>(it: &mut II, f: &mut FF) -> State<T>
+ where
+ II: Iterator<Item = T>,
+ FF: FnMut(T, T) -> T
+ {
+ // This function could be replaced with `it.next().ok_or(None)`,
+ // but half the useful tree_fold1 work is combining adjacent items,
+ // so put that in a form that LLVM is more likely to optimize well.
+
+ let a =
+ if let Some(v) = it.next() { v }
+ else { return Err(None) };
+ let b =
+ if let Some(v) = it.next() { v }
+ else { return Err(Some(a)) };
+ Ok(f(a, b))
+ }
+
+ fn inner<T, II, FF>(stop: usize, it: &mut II, f: &mut FF) -> State<T>
+ where
+ II: Iterator<Item = T>,
+ FF: FnMut(T, T) -> T
+ {
+ let mut x = inner0(it, f)?;
+ for height in 0..stop {
+ // Try to get another tree the same size with which to combine it,
+ // creating a new tree that's twice as big for next time around.
+ let next =
+ if height == 0 {
+ inner0(it, f)
+ } else {
+ inner(height, it, f)
+ };
+ match next {
+ Ok(y) => x = f(x, y),
+
+ // If we ran out of items, combine whatever we did manage
+ // to get. It's better combined with the current value
+ // than something in a parent frame, because the tree in
+ // the parent is always as least as big as this one.
+ Err(None) => return Err(Some(x)),
+ Err(Some(y)) => return Err(Some(f(x, y))),
+ }
+ }
+ Ok(x)
+ }
+
+ match inner(usize::max_value(), &mut self, &mut f) {
+ Err(x) => x,
+ _ => unreachable!(),
+ }
+ }
+
+ /// An iterator method that applies a function, producing a single, final value.
+ ///
+ /// `fold_while()` is basically equivalent to [`Iterator::fold`] but with additional support for
+ /// early exit via short-circuiting.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::FoldWhile::{Continue, Done};
+ ///
+ /// let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ ///
+ /// let mut result = 0;
+ ///
+ /// // for loop:
+ /// for i in &numbers {
+ /// if *i > 5 {
+ /// break;
+ /// }
+ /// result = result + i;
+ /// }
+ ///
+ /// // fold:
+ /// let result2 = numbers.iter().fold(0, |acc, x| {
+ /// if *x > 5 { acc } else { acc + x }
+ /// });
+ ///
+ /// // fold_while:
+ /// let result3 = numbers.iter().fold_while(0, |acc, x| {
+ /// if *x > 5 { Done(acc) } else { Continue(acc + x) }
+ /// }).into_inner();
+ ///
+ /// // they're the same
+ /// assert_eq!(result, result2);
+ /// assert_eq!(result2, result3);
+ /// ```
+ ///
+ /// The big difference between the computations of `result2` and `result3` is that while
+ /// `fold()` called the provided closure for every item of the callee iterator,
+ /// `fold_while()` actually stopped iterating as soon as it encountered `Fold::Done(_)`.
+ fn fold_while<B, F>(&mut self, init: B, mut f: F) -> FoldWhile<B>
+ where Self: Sized,
+ F: FnMut(B, Self::Item) -> FoldWhile<B>
+ {
+ use Result::{
+ Ok as Continue,
+ Err as Break,
+ };
+
+ let result = self.try_fold(init, #[inline(always)] |acc, v|
+ match f(acc, v) {
+ FoldWhile::Continue(acc) => Continue(acc),
+ FoldWhile::Done(acc) => Break(acc),
+ }
+ );
+
+ match result {
+ Continue(acc) => FoldWhile::Continue(acc),
+ Break(acc) => FoldWhile::Done(acc),
+ }
+ }
+
+ /// Iterate over the entire iterator and add all the elements.
+ ///
+ /// An empty iterator returns `None`, otherwise `Some(sum)`.
+ ///
+ /// # Panics
+ ///
+ /// When calling `sum1()` and a primitive integer type is being returned, this
+ /// method will panic if the computation overflows and debug assertions are
+ /// enabled.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let empty_sum = (1..1).sum1::<i32>();
+ /// assert_eq!(empty_sum, None);
+ ///
+ /// let nonempty_sum = (1..11).sum1::<i32>();
+ /// assert_eq!(nonempty_sum, Some(55));
+ /// ```
+ fn sum1<S>(mut self) -> Option<S>
+ where Self: Sized,
+ S: std::iter::Sum<Self::Item>,
+ {
+ self.next()
+ .map(|first| once(first).chain(self).sum())
+ }
+
+ /// Iterate over the entire iterator and multiply all the elements.
+ ///
+ /// An empty iterator returns `None`, otherwise `Some(product)`.
+ ///
+ /// # Panics
+ ///
+ /// When calling `product1()` and a primitive integer type is being returned,
+ /// method will panic if the computation overflows and debug assertions are
+ /// enabled.
+ ///
+ /// # Examples
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let empty_product = (1..1).product1::<i32>();
+ /// assert_eq!(empty_product, None);
+ ///
+ /// let nonempty_product = (1..11).product1::<i32>();
+ /// assert_eq!(nonempty_product, Some(3628800));
+ /// ```
+ fn product1<P>(mut self) -> Option<P>
+ where Self: Sized,
+ P: std::iter::Product<Self::Item>,
+ {
+ self.next()
+ .map(|first| once(first).chain(self).product())
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_unstable`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort the letters of the text in ascending order
+ /// let text = "bdacfe";
+ /// itertools::assert_equal(text.chars().sorted_unstable(),
+ /// "abcdef".chars());
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_unstable(self) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ Self::Item: Ord
+ {
+ // Use .sort_unstable() directly since it is not quite identical with
+ // .sort_by(Ord::cmp)
+ let mut v = Vec::from_iter(self);
+ v.sort_unstable();
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_unstable_by`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort people in descending order by age
+ /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)];
+ ///
+ /// let oldest_people_first = people
+ /// .into_iter()
+ /// .sorted_unstable_by(|a, b| Ord::cmp(&b.1, &a.1))
+ /// .map(|(person, _age)| person);
+ ///
+ /// itertools::assert_equal(oldest_people_first,
+ /// vec!["Jill", "Jack", "Jane", "John"]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_unstable_by<F>(self, cmp: F) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ F: FnMut(&Self::Item, &Self::Item) -> Ordering,
+ {
+ let mut v = Vec::from_iter(self);
+ v.sort_unstable_by(cmp);
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_unstable_by_key`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort people in descending order by age
+ /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)];
+ ///
+ /// let oldest_people_first = people
+ /// .into_iter()
+ /// .sorted_unstable_by_key(|x| -x.1)
+ /// .map(|(person, _age)| person);
+ ///
+ /// itertools::assert_equal(oldest_people_first,
+ /// vec!["Jill", "Jack", "Jane", "John"]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_unstable_by_key<K, F>(self, f: F) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ K: Ord,
+ F: FnMut(&Self::Item) -> K,
+ {
+ let mut v = Vec::from_iter(self);
+ v.sort_unstable_by_key(f);
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort the letters of the text in ascending order
+ /// let text = "bdacfe";
+ /// itertools::assert_equal(text.chars().sorted(),
+ /// "abcdef".chars());
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted(self) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ Self::Item: Ord
+ {
+ // Use .sort() directly since it is not quite identical with
+ // .sort_by(Ord::cmp)
+ let mut v = Vec::from_iter(self);
+ v.sort();
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_by`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort people in descending order by age
+ /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)];
+ ///
+ /// let oldest_people_first = people
+ /// .into_iter()
+ /// .sorted_by(|a, b| Ord::cmp(&b.1, &a.1))
+ /// .map(|(person, _age)| person);
+ ///
+ /// itertools::assert_equal(oldest_people_first,
+ /// vec!["Jill", "Jack", "Jane", "John"]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_by<F>(self, cmp: F) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ F: FnMut(&Self::Item, &Self::Item) -> Ordering,
+ {
+ let mut v = Vec::from_iter(self);
+ v.sort_by(cmp);
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_by_key`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort people in descending order by age
+ /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)];
+ ///
+ /// let oldest_people_first = people
+ /// .into_iter()
+ /// .sorted_by_key(|x| -x.1)
+ /// .map(|(person, _age)| person);
+ ///
+ /// itertools::assert_equal(oldest_people_first,
+ /// vec!["Jill", "Jack", "Jane", "John"]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_by_key<K, F>(self, f: F) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ K: Ord,
+ F: FnMut(&Self::Item) -> K,
+ {
+ let mut v = Vec::from_iter(self);
+ v.sort_by_key(f);
+ v.into_iter()
+ }
+
+ /// Sort all iterator elements into a new iterator in ascending order. The key function is
+ /// called exactly once per key.
+ ///
+ /// **Note:** This consumes the entire iterator, uses the
+ /// [`slice::sort_by_cached_key`] method and returns the result as a new
+ /// iterator that owns its elements.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // sort people in descending order by age
+ /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)];
+ ///
+ /// let oldest_people_first = people
+ /// .into_iter()
+ /// .sorted_by_cached_key(|x| -x.1)
+ /// .map(|(person, _age)| person);
+ ///
+ /// itertools::assert_equal(oldest_people_first,
+ /// vec!["Jill", "Jack", "Jane", "John"]);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn sorted_by_cached_key<K, F>(self, f: F) -> VecIntoIter<Self::Item>
+ where
+ Self: Sized,
+ K: Ord,
+ F: FnMut(&Self::Item) -> K,
+ {
+ let mut v = Vec::from_iter(self);
+ v.sort_by_cached_key(f);
+ v.into_iter()
+ }
+
+ /// Sort the k smallest elements into a new iterator, in ascending order.
+ ///
+ /// **Note:** This consumes the entire iterator, and returns the result
+ /// as a new iterator that owns its elements. If the input contains
+ /// less than k elements, the result is equivalent to `self.sorted()`.
+ ///
+ /// This is guaranteed to use `k * sizeof(Self::Item) + O(1)` memory
+ /// and `O(n log k)` time, with `n` the number of elements in the input.
+ ///
+ /// The sorted iterator, if directly collected to a `Vec`, is converted
+ /// without any extra copying or allocation cost.
+ ///
+ /// **Note:** This is functionally-equivalent to `self.sorted().take(k)`
+ /// but much more efficient.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// // A random permutation of 0..15
+ /// let numbers = vec![6, 9, 1, 14, 0, 4, 8, 7, 11, 2, 10, 3, 13, 12, 5];
+ ///
+ /// let five_smallest = numbers
+ /// .into_iter()
+ /// .k_smallest(5);
+ ///
+ /// itertools::assert_equal(five_smallest, 0..5);
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn k_smallest(self, k: usize) -> VecIntoIter<Self::Item>
+ where Self: Sized,
+ Self::Item: Ord
+ {
+ crate::k_smallest::k_smallest(self, k)
+ .into_sorted_vec()
+ .into_iter()
+ }
+
+ /// Collect all iterator elements into one of two
+ /// partitions. Unlike [`Iterator::partition`], each partition may
+ /// have a distinct type.
+ ///
+ /// ```
+ /// use itertools::{Itertools, Either};
+ ///
+ /// let successes_and_failures = vec![Ok(1), Err(false), Err(true), Ok(2)];
+ ///
+ /// let (successes, failures): (Vec<_>, Vec<_>) = successes_and_failures
+ /// .into_iter()
+ /// .partition_map(|r| {
+ /// match r {
+ /// Ok(v) => Either::Left(v),
+ /// Err(v) => Either::Right(v),
+ /// }
+ /// });
+ ///
+ /// assert_eq!(successes, [1, 2]);
+ /// assert_eq!(failures, [false, true]);
+ /// ```
+ fn partition_map<A, B, F, L, R>(self, mut predicate: F) -> (A, B)
+ where Self: Sized,
+ F: FnMut(Self::Item) -> Either<L, R>,
+ A: Default + Extend<L>,
+ B: Default + Extend<R>,
+ {
+ let mut left = A::default();
+ let mut right = B::default();
+
+ self.for_each(|val| match predicate(val) {
+ Either::Left(v) => left.extend(Some(v)),
+ Either::Right(v) => right.extend(Some(v)),
+ });
+
+ (left, right)
+ }
+
+ /// Partition a sequence of `Result`s into one list of all the `Ok` elements
+ /// and another list of all the `Err` elements.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let successes_and_failures = vec![Ok(1), Err(false), Err(true), Ok(2)];
+ ///
+ /// let (successes, failures): (Vec<_>, Vec<_>) = successes_and_failures
+ /// .into_iter()
+ /// .partition_result();
+ ///
+ /// assert_eq!(successes, [1, 2]);
+ /// assert_eq!(failures, [false, true]);
+ /// ```
+ fn partition_result<A, B, T, E>(self) -> (A, B)
+ where
+ Self: Iterator<Item = Result<T, E>> + Sized,
+ A: Default + Extend<T>,
+ B: Default + Extend<E>,
+ {
+ self.partition_map(|r| match r {
+ Ok(v) => Either::Left(v),
+ Err(v) => Either::Right(v),
+ })
+ }
+
+ /// Return a `HashMap` of keys mapped to `Vec`s of values. Keys and values
+ /// are taken from `(Key, Value)` tuple pairs yielded by the input iterator.
+ ///
+ /// Essentially a shorthand for `.into_grouping_map().collect::<Vec<_>>()`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let data = vec![(0, 10), (2, 12), (3, 13), (0, 20), (3, 33), (2, 42)];
+ /// let lookup = data.into_iter().into_group_map();
+ ///
+ /// assert_eq!(lookup[&0], vec![10, 20]);
+ /// assert_eq!(lookup.get(&1), None);
+ /// assert_eq!(lookup[&2], vec![12, 42]);
+ /// assert_eq!(lookup[&3], vec![13, 33]);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn into_group_map<K, V>(self) -> HashMap<K, Vec<V>>
+ where Self: Iterator<Item=(K, V)> + Sized,
+ K: Hash + Eq,
+ {
+ group_map::into_group_map(self)
+ }
+
+ /// Return an `Iterator` on a `HashMap`. Keys mapped to `Vec`s of values. The key is specified
+ /// in the closure.
+ ///
+ /// Essentially a shorthand for `.into_grouping_map_by(f).collect::<Vec<_>>()`.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use std::collections::HashMap;
+ ///
+ /// let data = vec![(0, 10), (2, 12), (3, 13), (0, 20), (3, 33), (2, 42)];
+ /// let lookup: HashMap<u32,Vec<(u32, u32)>> =
+ /// data.clone().into_iter().into_group_map_by(|a| a.0);
+ ///
+ /// assert_eq!(lookup[&0], vec![(0,10),(0,20)]);
+ /// assert_eq!(lookup.get(&1), None);
+ /// assert_eq!(lookup[&2], vec![(2,12), (2,42)]);
+ /// assert_eq!(lookup[&3], vec![(3,13), (3,33)]);
+ ///
+ /// assert_eq!(
+ /// data.into_iter()
+ /// .into_group_map_by(|x| x.0)
+ /// .into_iter()
+ /// .map(|(key, values)| (key, values.into_iter().fold(0,|acc, (_,v)| acc + v )))
+ /// .collect::<HashMap<u32,u32>>()[&0],
+ /// 30,
+ /// );
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn into_group_map_by<K, V, F>(self, f: F) -> HashMap<K, Vec<V>>
+ where
+ Self: Iterator<Item=V> + Sized,
+ K: Hash + Eq,
+ F: Fn(&V) -> K,
+ {
+ group_map::into_group_map_by(self, f)
+ }
+
+ /// Constructs a `GroupingMap` to be used later with one of the efficient
+ /// group-and-fold operations it allows to perform.
+ ///
+ /// The input iterator must yield item in the form of `(K, V)` where the
+ /// value of type `K` will be used as key to identify the groups and the
+ /// value of type `V` as value for the folding operation.
+ ///
+ /// See [`GroupingMap`] for more informations
+ /// on what operations are available.
+ #[cfg(feature = "use_std")]
+ fn into_grouping_map<K, V>(self) -> GroupingMap<Self>
+ where Self: Iterator<Item=(K, V)> + Sized,
+ K: Hash + Eq,
+ {
+ grouping_map::new(self)
+ }
+
+ /// Constructs a `GroupingMap` to be used later with one of the efficient
+ /// group-and-fold operations it allows to perform.
+ ///
+ /// The values from this iterator will be used as values for the folding operation
+ /// while the keys will be obtained from the values by calling `key_mapper`.
+ ///
+ /// See [`GroupingMap`] for more informations
+ /// on what operations are available.
+ #[cfg(feature = "use_std")]
+ fn into_grouping_map_by<K, V, F>(self, key_mapper: F) -> GroupingMapBy<Self, F>
+ where Self: Iterator<Item=V> + Sized,
+ K: Hash + Eq,
+ F: FnMut(&V) -> K
+ {
+ grouping_map::new(grouping_map::MapForGrouping::new(self, key_mapper))
+ }
+
+ /// Return all minimum elements of an iterator.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().min_set(), Vec::<&i32>::new());
+ ///
+ /// let a = [1];
+ /// assert_eq!(a.iter().min_set(), vec![&1]);
+ ///
+ /// let a = [1, 2, 3, 4, 5];
+ /// assert_eq!(a.iter().min_set(), vec![&1]);
+ ///
+ /// let a = [1, 1, 1, 1];
+ /// assert_eq!(a.iter().min_set(), vec![&1, &1, &1, &1]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn min_set(self) -> Vec<Self::Item>
+ where Self: Sized, Self::Item: Ord
+ {
+ extrema_set::min_set_impl(self, |_| (), |x, y, _, _| x.cmp(y))
+ }
+
+ /// Return all minimum elements of an iterator, as determined by
+ /// the specified function.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # use std::cmp::Ordering;
+ /// use itertools::Itertools;
+ ///
+ /// let a: [(i32, i32); 0] = [];
+ /// assert_eq!(a.iter().min_set_by(|_, _| Ordering::Equal), Vec::<&(i32, i32)>::new());
+ ///
+ /// let a = [(1, 2)];
+ /// assert_eq!(a.iter().min_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2)]);
+ ///
+ /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)];
+ /// assert_eq!(a.iter().min_set_by(|&&(_,k1), &&(_,k2)| k1.cmp(&k2)), vec![&(1, 2), &(2, 2)]);
+ ///
+ /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)];
+ /// assert_eq!(a.iter().min_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn min_set_by<F>(self, mut compare: F) -> Vec<Self::Item>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ extrema_set::min_set_impl(
+ self,
+ |_| (),
+ |x, y, _, _| compare(x, y)
+ )
+ }
+
+ /// Return all minimum elements of an iterator, as determined by
+ /// the specified function.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [(i32, i32); 0] = [];
+ /// assert_eq!(a.iter().min_set_by_key(|_| ()), Vec::<&(i32, i32)>::new());
+ ///
+ /// let a = [(1, 2)];
+ /// assert_eq!(a.iter().min_set_by_key(|&&(k,_)| k), vec![&(1, 2)]);
+ ///
+ /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)];
+ /// assert_eq!(a.iter().min_set_by_key(|&&(_, k)| k), vec![&(1, 2), &(2, 2)]);
+ ///
+ /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)];
+ /// assert_eq!(a.iter().min_set_by_key(|&&(k, _)| k), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn min_set_by_key<K, F>(self, key: F) -> Vec<Self::Item>
+ where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K
+ {
+ extrema_set::min_set_impl(self, key, |_, _, kx, ky| kx.cmp(ky))
+ }
+
+ /// Return all maximum elements of an iterator.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().max_set(), Vec::<&i32>::new());
+ ///
+ /// let a = [1];
+ /// assert_eq!(a.iter().max_set(), vec![&1]);
+ ///
+ /// let a = [1, 2, 3, 4, 5];
+ /// assert_eq!(a.iter().max_set(), vec![&5]);
+ ///
+ /// let a = [1, 1, 1, 1];
+ /// assert_eq!(a.iter().max_set(), vec![&1, &1, &1, &1]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn max_set(self) -> Vec<Self::Item>
+ where Self: Sized, Self::Item: Ord
+ {
+ extrema_set::max_set_impl(self, |_| (), |x, y, _, _| x.cmp(y))
+ }
+
+ /// Return all maximum elements of an iterator, as determined by
+ /// the specified function.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// # use std::cmp::Ordering;
+ /// use itertools::Itertools;
+ ///
+ /// let a: [(i32, i32); 0] = [];
+ /// assert_eq!(a.iter().max_set_by(|_, _| Ordering::Equal), Vec::<&(i32, i32)>::new());
+ ///
+ /// let a = [(1, 2)];
+ /// assert_eq!(a.iter().max_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2)]);
+ ///
+ /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)];
+ /// assert_eq!(a.iter().max_set_by(|&&(_,k1), &&(_,k2)| k1.cmp(&k2)), vec![&(3, 9), &(5, 9)]);
+ ///
+ /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)];
+ /// assert_eq!(a.iter().max_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn max_set_by<F>(self, mut compare: F) -> Vec<Self::Item>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ extrema_set::max_set_impl(
+ self,
+ |_| (),
+ |x, y, _, _| compare(x, y)
+ )
+ }
+
+ /// Return all minimum elements of an iterator, as determined by
+ /// the specified function.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [(i32, i32); 0] = [];
+ /// assert_eq!(a.iter().max_set_by_key(|_| ()), Vec::<&(i32, i32)>::new());
+ ///
+ /// let a = [(1, 2)];
+ /// assert_eq!(a.iter().max_set_by_key(|&&(k,_)| k), vec![&(1, 2)]);
+ ///
+ /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)];
+ /// assert_eq!(a.iter().max_set_by_key(|&&(_, k)| k), vec![&(3, 9), &(5, 9)]);
+ ///
+ /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)];
+ /// assert_eq!(a.iter().max_set_by_key(|&&(k, _)| k), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]);
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ #[cfg(feature = "use_std")]
+ fn max_set_by_key<K, F>(self, key: F) -> Vec<Self::Item>
+ where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K
+ {
+ extrema_set::max_set_impl(self, key, |_, _, kx, ky| kx.cmp(ky))
+ }
+
+ /// Return the minimum and maximum elements in the iterator.
+ ///
+ /// The return type `MinMaxResult` is an enum of three variants:
+ ///
+ /// - `NoElements` if the iterator is empty.
+ /// - `OneElement(x)` if the iterator has exactly one element.
+ /// - `MinMax(x, y)` is returned otherwise, where `x <= y`. Two
+ /// values are equal if and only if there is more than one
+ /// element in the iterator and all elements are equal.
+ ///
+ /// On an iterator of length `n`, `minmax` does `1.5 * n` comparisons,
+ /// and so is faster than calling `min` and `max` separately which does
+ /// `2 * n` comparisons.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax};
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().minmax(), NoElements);
+ ///
+ /// let a = [1];
+ /// assert_eq!(a.iter().minmax(), OneElement(&1));
+ ///
+ /// let a = [1, 2, 3, 4, 5];
+ /// assert_eq!(a.iter().minmax(), MinMax(&1, &5));
+ ///
+ /// let a = [1, 1, 1, 1];
+ /// assert_eq!(a.iter().minmax(), MinMax(&1, &1));
+ /// ```
+ ///
+ /// The elements can be floats but no particular result is guaranteed
+ /// if an element is NaN.
+ fn minmax(self) -> MinMaxResult<Self::Item>
+ where Self: Sized, Self::Item: PartialOrd
+ {
+ minmax::minmax_impl(self, |_| (), |x, y, _, _| x < y)
+ }
+
+ /// Return the minimum and maximum element of an iterator, as determined by
+ /// the specified function.
+ ///
+ /// The return value is a variant of [`MinMaxResult`] like for [`.minmax()`](Itertools::minmax).
+ ///
+ /// For the minimum, the first minimal element is returned. For the maximum,
+ /// the last maximal element wins. This matches the behavior of the standard
+ /// [`Iterator::min`] and [`Iterator::max`] methods.
+ ///
+ /// The keys can be floats but no particular result is guaranteed
+ /// if a key is NaN.
+ fn minmax_by_key<K, F>(self, key: F) -> MinMaxResult<Self::Item>
+ where Self: Sized, K: PartialOrd, F: FnMut(&Self::Item) -> K
+ {
+ minmax::minmax_impl(self, key, |_, _, xk, yk| xk < yk)
+ }
+
+ /// Return the minimum and maximum element of an iterator, as determined by
+ /// the specified comparison function.
+ ///
+ /// The return value is a variant of [`MinMaxResult`] like for [`.minmax()`](Itertools::minmax).
+ ///
+ /// For the minimum, the first minimal element is returned. For the maximum,
+ /// the last maximal element wins. This matches the behavior of the standard
+ /// [`Iterator::min`] and [`Iterator::max`] methods.
+ fn minmax_by<F>(self, mut compare: F) -> MinMaxResult<Self::Item>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ minmax::minmax_impl(
+ self,
+ |_| (),
+ |x, y, _, _| Ordering::Less == compare(x, y)
+ )
+ }
+
+ /// Return the position of the maximum element in the iterator.
+ ///
+ /// If several elements are equally maximum, the position of the
+ /// last of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_max(), None);
+ ///
+ /// let a = [-3, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_max(), Some(3));
+ ///
+ /// let a = [1, 1, -1, -1];
+ /// assert_eq!(a.iter().position_max(), Some(1));
+ /// ```
+ fn position_max(self) -> Option<usize>
+ where Self: Sized, Self::Item: Ord
+ {
+ self.enumerate()
+ .max_by(|x, y| Ord::cmp(&x.1, &y.1))
+ .map(|x| x.0)
+ }
+
+ /// Return the position of the maximum element in the iterator, as
+ /// determined by the specified function.
+ ///
+ /// If several elements are equally maximum, the position of the
+ /// last of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), None);
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), Some(4));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), Some(3));
+ /// ```
+ fn position_max_by_key<K, F>(self, mut key: F) -> Option<usize>
+ where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K
+ {
+ self.enumerate()
+ .max_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1)))
+ .map(|x| x.0)
+ }
+
+ /// Return the position of the maximum element in the iterator, as
+ /// determined by the specified comparison function.
+ ///
+ /// If several elements are equally maximum, the position of the
+ /// last of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), None);
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), Some(3));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), Some(1));
+ /// ```
+ fn position_max_by<F>(self, mut compare: F) -> Option<usize>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ self.enumerate()
+ .max_by(|x, y| compare(&x.1, &y.1))
+ .map(|x| x.0)
+ }
+
+ /// Return the position of the minimum element in the iterator.
+ ///
+ /// If several elements are equally minimum, the position of the
+ /// first of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_min(), None);
+ ///
+ /// let a = [-3, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_min(), Some(4));
+ ///
+ /// let a = [1, 1, -1, -1];
+ /// assert_eq!(a.iter().position_min(), Some(2));
+ /// ```
+ fn position_min(self) -> Option<usize>
+ where Self: Sized, Self::Item: Ord
+ {
+ self.enumerate()
+ .min_by(|x, y| Ord::cmp(&x.1, &y.1))
+ .map(|x| x.0)
+ }
+
+ /// Return the position of the minimum element in the iterator, as
+ /// determined by the specified function.
+ ///
+ /// If several elements are equally minimum, the position of the
+ /// first of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), None);
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), Some(1));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), Some(0));
+ /// ```
+ fn position_min_by_key<K, F>(self, mut key: F) -> Option<usize>
+ where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K
+ {
+ self.enumerate()
+ .min_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1)))
+ .map(|x| x.0)
+ }
+
+ /// Return the position of the minimum element in the iterator, as
+ /// determined by the specified comparison function.
+ ///
+ /// If several elements are equally minimum, the position of the
+ /// first of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), None);
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), Some(4));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), Some(2));
+ /// ```
+ fn position_min_by<F>(self, mut compare: F) -> Option<usize>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ self.enumerate()
+ .min_by(|x, y| compare(&x.1, &y.1))
+ .map(|x| x.0)
+ }
+
+ /// Return the positions of the minimum and maximum elements in
+ /// the iterator.
+ ///
+ /// The return type [`MinMaxResult`] is an enum of three variants:
+ ///
+ /// - `NoElements` if the iterator is empty.
+ /// - `OneElement(xpos)` if the iterator has exactly one element.
+ /// - `MinMax(xpos, ypos)` is returned otherwise, where the
+ /// element at `xpos` ≤ the element at `ypos`. While the
+ /// referenced elements themselves may be equal, `xpos` cannot
+ /// be equal to `ypos`.
+ ///
+ /// On an iterator of length `n`, `position_minmax` does `1.5 * n`
+ /// comparisons, and so is faster than calling `position_min` and
+ /// `position_max` separately which does `2 * n` comparisons.
+ ///
+ /// For the minimum, if several elements are equally minimum, the
+ /// position of the first of them is returned. For the maximum, if
+ /// several elements are equally maximum, the position of the last
+ /// of them is returned.
+ ///
+ /// The elements can be floats but no particular result is
+ /// guaranteed if an element is NaN.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax};
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_minmax(), NoElements);
+ ///
+ /// let a = [10];
+ /// assert_eq!(a.iter().position_minmax(), OneElement(0));
+ ///
+ /// let a = [-3, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_minmax(), MinMax(4, 3));
+ ///
+ /// let a = [1, 1, -1, -1];
+ /// assert_eq!(a.iter().position_minmax(), MinMax(2, 1));
+ /// ```
+ fn position_minmax(self) -> MinMaxResult<usize>
+ where Self: Sized, Self::Item: PartialOrd
+ {
+ use crate::MinMaxResult::{NoElements, OneElement, MinMax};
+ match minmax::minmax_impl(self.enumerate(), |_| (), |x, y, _, _| x.1 < y.1) {
+ NoElements => NoElements,
+ OneElement(x) => OneElement(x.0),
+ MinMax(x, y) => MinMax(x.0, y.0),
+ }
+ }
+
+ /// Return the postions of the minimum and maximum elements of an
+ /// iterator, as determined by the specified function.
+ ///
+ /// The return value is a variant of [`MinMaxResult`] like for
+ /// [`position_minmax`].
+ ///
+ /// For the minimum, if several elements are equally minimum, the
+ /// position of the first of them is returned. For the maximum, if
+ /// several elements are equally maximum, the position of the last
+ /// of them is returned.
+ ///
+ /// The keys can be floats but no particular result is guaranteed
+ /// if a key is NaN.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax};
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), NoElements);
+ ///
+ /// let a = [10_i32];
+ /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), OneElement(0));
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), MinMax(1, 4));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), MinMax(0, 3));
+ /// ```
+ ///
+ /// [`position_minmax`]: Self::position_minmax
+ fn position_minmax_by_key<K, F>(self, mut key: F) -> MinMaxResult<usize>
+ where Self: Sized, K: PartialOrd, F: FnMut(&Self::Item) -> K
+ {
+ use crate::MinMaxResult::{NoElements, OneElement, MinMax};
+ match self.enumerate().minmax_by_key(|e| key(&e.1)) {
+ NoElements => NoElements,
+ OneElement(x) => OneElement(x.0),
+ MinMax(x, y) => MinMax(x.0, y.0),
+ }
+ }
+
+ /// Return the postions of the minimum and maximum elements of an
+ /// iterator, as determined by the specified comparison function.
+ ///
+ /// The return value is a variant of [`MinMaxResult`] like for
+ /// [`position_minmax`].
+ ///
+ /// For the minimum, if several elements are equally minimum, the
+ /// position of the first of them is returned. For the maximum, if
+ /// several elements are equally maximum, the position of the last
+ /// of them is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax};
+ ///
+ /// let a: [i32; 0] = [];
+ /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), NoElements);
+ ///
+ /// let a = [10_i32];
+ /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), OneElement(0));
+ ///
+ /// let a = [-3_i32, 0, 1, 5, -10];
+ /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), MinMax(4, 3));
+ ///
+ /// let a = [1_i32, 1, -1, -1];
+ /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), MinMax(2, 1));
+ /// ```
+ ///
+ /// [`position_minmax`]: Self::position_minmax
+ fn position_minmax_by<F>(self, mut compare: F) -> MinMaxResult<usize>
+ where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering
+ {
+ use crate::MinMaxResult::{NoElements, OneElement, MinMax};
+ match self.enumerate().minmax_by(|x, y| compare(&x.1, &y.1)) {
+ NoElements => NoElements,
+ OneElement(x) => OneElement(x.0),
+ MinMax(x, y) => MinMax(x.0, y.0),
+ }
+ }
+
+ /// If the iterator yields exactly one element, that element will be returned, otherwise
+ /// an error will be returned containing an iterator that has the same output as the input
+ /// iterator.
+ ///
+ /// This provides an additional layer of validation over just calling `Iterator::next()`.
+ /// If your assumption that there should only be one element yielded is false this provides
+ /// the opportunity to detect and handle that, preventing errors at a distance.
+ ///
+ /// # Examples
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// assert_eq!((0..10).filter(|&x| x == 2).exactly_one().unwrap(), 2);
+ /// assert!((0..10).filter(|&x| x > 1 && x < 4).exactly_one().unwrap_err().eq(2..4));
+ /// assert!((0..10).filter(|&x| x > 1 && x < 5).exactly_one().unwrap_err().eq(2..5));
+ /// assert!((0..10).filter(|&_| false).exactly_one().unwrap_err().eq(0..0));
+ /// ```
+ fn exactly_one(mut self) -> Result<Self::Item, ExactlyOneError<Self>>
+ where
+ Self: Sized,
+ {
+ match self.next() {
+ Some(first) => {
+ match self.next() {
+ Some(second) => {
+ Err(ExactlyOneError::new(Some(Either::Left([first, second])), self))
+ }
+ None => {
+ Ok(first)
+ }
+ }
+ }
+ None => Err(ExactlyOneError::new(None, self)),
+ }
+ }
+
+ /// If the iterator yields no elements, Ok(None) will be returned. If the iterator yields
+ /// exactly one element, that element will be returned, otherwise an error will be returned
+ /// containing an iterator that has the same output as the input iterator.
+ ///
+ /// This provides an additional layer of validation over just calling `Iterator::next()`.
+ /// If your assumption that there should be at most one element yielded is false this provides
+ /// the opportunity to detect and handle that, preventing errors at a distance.
+ ///
+ /// # Examples
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// assert_eq!((0..10).filter(|&x| x == 2).at_most_one().unwrap(), Some(2));
+ /// assert!((0..10).filter(|&x| x > 1 && x < 4).at_most_one().unwrap_err().eq(2..4));
+ /// assert!((0..10).filter(|&x| x > 1 && x < 5).at_most_one().unwrap_err().eq(2..5));
+ /// assert_eq!((0..10).filter(|&_| false).at_most_one().unwrap(), None);
+ /// ```
+ fn at_most_one(mut self) -> Result<Option<Self::Item>, ExactlyOneError<Self>>
+ where
+ Self: Sized,
+ {
+ match self.next() {
+ Some(first) => {
+ match self.next() {
+ Some(second) => {
+ Err(ExactlyOneError::new(Some(Either::Left([first, second])), self))
+ }
+ None => {
+ Ok(Some(first))
+ }
+ }
+ }
+ None => Ok(None),
+ }
+ }
+
+ /// An iterator adaptor that allows the user to peek at multiple `.next()`
+ /// values without advancing the base iterator.
+ ///
+ /// # Examples
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut iter = (0..10).multipeek();
+ /// assert_eq!(iter.peek(), Some(&0));
+ /// assert_eq!(iter.peek(), Some(&1));
+ /// assert_eq!(iter.peek(), Some(&2));
+ /// assert_eq!(iter.next(), Some(0));
+ /// assert_eq!(iter.peek(), Some(&1));
+ /// ```
+ #[cfg(feature = "use_alloc")]
+ fn multipeek(self) -> MultiPeek<Self>
+ where
+ Self: Sized,
+ {
+ multipeek_impl::multipeek(self)
+ }
+
+ /// Collect the items in this iterator and return a `HashMap` which
+ /// contains each item that appears in the iterator and the number
+ /// of times it appears.
+ ///
+ /// # Examples
+ /// ```
+ /// # use itertools::Itertools;
+ /// let counts = [1, 1, 1, 3, 3, 5].into_iter().counts();
+ /// assert_eq!(counts[&1], 3);
+ /// assert_eq!(counts[&3], 2);
+ /// assert_eq!(counts[&5], 1);
+ /// assert_eq!(counts.get(&0), None);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn counts(self) -> HashMap<Self::Item, usize>
+ where
+ Self: Sized,
+ Self::Item: Eq + Hash,
+ {
+ let mut counts = HashMap::new();
+ self.for_each(|item| *counts.entry(item).or_default() += 1);
+ counts
+ }
+
+ /// Collect the items in this iterator and return a `HashMap` which
+ /// contains each item that appears in the iterator and the number
+ /// of times it appears,
+ /// determining identity using a keying function.
+ ///
+ /// ```
+ /// # use itertools::Itertools;
+ /// struct Character {
+ /// first_name: &'static str,
+ /// last_name: &'static str,
+ /// }
+ ///
+ /// let characters =
+ /// vec![
+ /// Character { first_name: "Amy", last_name: "Pond" },
+ /// Character { first_name: "Amy", last_name: "Wong" },
+ /// Character { first_name: "Amy", last_name: "Santiago" },
+ /// Character { first_name: "James", last_name: "Bond" },
+ /// Character { first_name: "James", last_name: "Sullivan" },
+ /// Character { first_name: "James", last_name: "Norington" },
+ /// Character { first_name: "James", last_name: "Kirk" },
+ /// ];
+ ///
+ /// let first_name_frequency =
+ /// characters
+ /// .into_iter()
+ /// .counts_by(|c| c.first_name);
+ ///
+ /// assert_eq!(first_name_frequency["Amy"], 3);
+ /// assert_eq!(first_name_frequency["James"], 4);
+ /// assert_eq!(first_name_frequency.contains_key("Asha"), false);
+ /// ```
+ #[cfg(feature = "use_std")]
+ fn counts_by<K, F>(self, f: F) -> HashMap<K, usize>
+ where
+ Self: Sized,
+ K: Eq + Hash,
+ F: FnMut(Self::Item) -> K,
+ {
+ self.map(f).counts()
+ }
+
+ /// Converts an iterator of tuples into a tuple of containers.
+ ///
+ /// `unzip()` consumes an entire iterator of n-ary tuples, producing `n` collections, one for each
+ /// column.
+ ///
+ /// This function is, in some sense, the opposite of [`multizip`].
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let inputs = vec![(1, 2, 3), (4, 5, 6), (7, 8, 9)];
+ ///
+ /// let (a, b, c): (Vec<_>, Vec<_>, Vec<_>) = inputs
+ /// .into_iter()
+ /// .multiunzip();
+ ///
+ /// assert_eq!(a, vec![1, 4, 7]);
+ /// assert_eq!(b, vec![2, 5, 8]);
+ /// assert_eq!(c, vec![3, 6, 9]);
+ /// ```
+ fn multiunzip<FromI>(self) -> FromI
+ where
+ Self: Sized + MultiUnzip<FromI>,
+ {
+ MultiUnzip::multiunzip(self)
+ }
+}
+
+impl<T: ?Sized> Itertools for T where T: Iterator { }
+
+/// Return `true` if both iterables produce equal sequences
+/// (elements pairwise equal and sequences of the same length),
+/// `false` otherwise.
+///
+/// [`IntoIterator`] enabled version of [`Iterator::eq`].
+///
+/// ```
+/// assert!(itertools::equal(vec![1, 2, 3], 1..4));
+/// assert!(!itertools::equal(&[0, 0], &[0, 0, 0]));
+/// ```
+pub fn equal<I, J>(a: I, b: J) -> bool
+ where I: IntoIterator,
+ J: IntoIterator,
+ I::Item: PartialEq<J::Item>
+{
+ a.into_iter().eq(b)
+}
+
+/// Assert that two iterables produce equal sequences, with the same
+/// semantics as [`equal(a, b)`](equal).
+///
+/// **Panics** on assertion failure with a message that shows the
+/// two iteration elements.
+///
+/// ```ignore
+/// assert_equal("exceed".split('c'), "excess".split('c'));
+/// // ^PANIC: panicked at 'Failed assertion Some("eed") == Some("ess") for iteration 1',
+/// ```
+pub fn assert_equal<I, J>(a: I, b: J)
+ where I: IntoIterator,
+ J: IntoIterator,
+ I::Item: fmt::Debug + PartialEq<J::Item>,
+ J::Item: fmt::Debug,
+{
+ let mut ia = a.into_iter();
+ let mut ib = b.into_iter();
+ let mut i = 0;
+ loop {
+ match (ia.next(), ib.next()) {
+ (None, None) => return,
+ (a, b) => {
+ let equal = match (&a, &b) {
+ (&Some(ref a), &Some(ref b)) => a == b,
+ _ => false,
+ };
+ assert!(equal, "Failed assertion {a:?} == {b:?} for iteration {i}",
+ i=i, a=a, b=b);
+ i += 1;
+ }
+ }
+ }
+}
+
+/// Partition a sequence using predicate `pred` so that elements
+/// that map to `true` are placed before elements which map to `false`.
+///
+/// The order within the partitions is arbitrary.
+///
+/// Return the index of the split point.
+///
+/// ```
+/// use itertools::partition;
+///
+/// # // use repeated numbers to not promise any ordering
+/// let mut data = [7, 1, 1, 7, 1, 1, 7];
+/// let split_index = partition(&mut data, |elt| *elt >= 3);
+///
+/// assert_eq!(data, [7, 7, 7, 1, 1, 1, 1]);
+/// assert_eq!(split_index, 3);
+/// ```
+pub fn partition<'a, A: 'a, I, F>(iter: I, mut pred: F) -> usize
+ where I: IntoIterator<Item = &'a mut A>,
+ I::IntoIter: DoubleEndedIterator,
+ F: FnMut(&A) -> bool
+{
+ let mut split_index = 0;
+ let mut iter = iter.into_iter();
+ 'main: while let Some(front) = iter.next() {
+ if !pred(front) {
+ loop {
+ match iter.next_back() {
+ Some(back) => if pred(back) {
+ std::mem::swap(front, back);
+ break;
+ },
+ None => break 'main,
+ }
+ }
+ }
+ split_index += 1;
+ }
+ split_index
+}
+
+/// An enum used for controlling the execution of `fold_while`.
+///
+/// See [`.fold_while()`](Itertools::fold_while) for more information.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum FoldWhile<T> {
+ /// Continue folding with this value
+ Continue(T),
+ /// Fold is complete and will return this value
+ Done(T),
+}
+
+impl<T> FoldWhile<T> {
+ /// Return the value in the continue or done.
+ pub fn into_inner(self) -> T {
+ match self {
+ FoldWhile::Continue(x) | FoldWhile::Done(x) => x,
+ }
+ }
+
+ /// Return true if `self` is `Done`, false if it is `Continue`.
+ pub fn is_done(&self) -> bool {
+ match *self {
+ FoldWhile::Continue(_) => false,
+ FoldWhile::Done(_) => true,
+ }
+ }
+}
--- /dev/null
+use std::cmp::Ordering;
+use std::iter::Fuse;
+use std::fmt;
+
+use super::adaptors::{PutBack, put_back};
+use crate::either_or_both::EitherOrBoth;
+#[cfg(doc)]
+use crate::Itertools;
+
+/// Return an iterator adaptor that merge-joins items from the two base iterators in ascending order.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::merge_join_by`].
+pub fn merge_join_by<I, J, F>(left: I, right: J, cmp_fn: F)
+ -> MergeJoinBy<I::IntoIter, J::IntoIter, F>
+ where I: IntoIterator,
+ J: IntoIterator,
+ F: FnMut(&I::Item, &J::Item) -> Ordering
+{
+ MergeJoinBy {
+ left: put_back(left.into_iter().fuse()),
+ right: put_back(right.into_iter().fuse()),
+ cmp_fn,
+ }
+}
+
+/// An iterator adaptor that merge-joins items from the two base iterators in ascending order.
+///
+/// See [`.merge_join_by()`](crate::Itertools::merge_join_by) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct MergeJoinBy<I: Iterator, J: Iterator, F> {
+ left: PutBack<Fuse<I>>,
+ right: PutBack<Fuse<J>>,
+ cmp_fn: F
+}
+
+impl<I, J, F> Clone for MergeJoinBy<I, J, F>
+ where I: Iterator,
+ J: Iterator,
+ PutBack<Fuse<I>>: Clone,
+ PutBack<Fuse<J>>: Clone,
+ F: Clone,
+{
+ clone_fields!(left, right, cmp_fn);
+}
+
+impl<I, J, F> fmt::Debug for MergeJoinBy<I, J, F>
+ where I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug,
+ J: Iterator + fmt::Debug,
+ J::Item: fmt::Debug,
+{
+ debug_fmt_fields!(MergeJoinBy, left, right);
+}
+
+impl<I, J, F> Iterator for MergeJoinBy<I, J, F>
+ where I: Iterator,
+ J: Iterator,
+ F: FnMut(&I::Item, &J::Item) -> Ordering
+{
+ type Item = EitherOrBoth<I::Item, J::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match (self.left.next(), self.right.next()) {
+ (None, None) => None,
+ (Some(left), None) =>
+ Some(EitherOrBoth::Left(left)),
+ (None, Some(right)) =>
+ Some(EitherOrBoth::Right(right)),
+ (Some(left), Some(right)) => {
+ match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal =>
+ Some(EitherOrBoth::Both(left, right)),
+ Ordering::Less => {
+ self.right.put_back(right);
+ Some(EitherOrBoth::Left(left))
+ },
+ Ordering::Greater => {
+ self.left.put_back(left);
+ Some(EitherOrBoth::Right(right))
+ }
+ }
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (a_lower, a_upper) = self.left.size_hint();
+ let (b_lower, b_upper) = self.right.size_hint();
+
+ let lower = ::std::cmp::max(a_lower, b_lower);
+
+ let upper = match (a_upper, b_upper) {
+ (Some(x), Some(y)) => x.checked_add(y),
+ _ => None,
+ };
+
+ (lower, upper)
+ }
+
+ fn count(mut self) -> usize {
+ let mut count = 0;
+ loop {
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break count,
+ (Some(_left), None) => break count + 1 + self.left.into_parts().1.count(),
+ (None, Some(_right)) => break count + 1 + self.right.into_parts().1.count(),
+ (Some(left), Some(right)) => {
+ count += 1;
+ match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => {}
+ Ordering::Less => self.right.put_back(right),
+ Ordering::Greater => self.left.put_back(left),
+ }
+ }
+ }
+ }
+ }
+
+ fn last(mut self) -> Option<Self::Item> {
+ let mut previous_element = None;
+ loop {
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break previous_element,
+ (Some(left), None) => {
+ break Some(EitherOrBoth::Left(
+ self.left.into_parts().1.last().unwrap_or(left),
+ ))
+ }
+ (None, Some(right)) => {
+ break Some(EitherOrBoth::Right(
+ self.right.into_parts().1.last().unwrap_or(right),
+ ))
+ }
+ (Some(left), Some(right)) => {
+ previous_element = match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => Some(EitherOrBoth::Both(left, right)),
+ Ordering::Less => {
+ self.right.put_back(right);
+ Some(EitherOrBoth::Left(left))
+ }
+ Ordering::Greater => {
+ self.left.put_back(left);
+ Some(EitherOrBoth::Right(right))
+ }
+ }
+ }
+ }
+ }
+ }
+
+ fn nth(&mut self, mut n: usize) -> Option<Self::Item> {
+ loop {
+ if n == 0 {
+ break self.next();
+ }
+ n -= 1;
+ match (self.left.next(), self.right.next()) {
+ (None, None) => break None,
+ (Some(_left), None) => break self.left.nth(n).map(EitherOrBoth::Left),
+ (None, Some(_right)) => break self.right.nth(n).map(EitherOrBoth::Right),
+ (Some(left), Some(right)) => match (self.cmp_fn)(&left, &right) {
+ Ordering::Equal => {}
+ Ordering::Less => self.right.put_back(right),
+ Ordering::Greater => self.left.put_back(left),
+ },
+ }
+ }
+ }
+}
--- /dev/null
+
+/// `MinMaxResult` is an enum returned by `minmax`.
+///
+/// See [`.minmax()`](crate::Itertools::minmax) for more detail.
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub enum MinMaxResult<T> {
+ /// Empty iterator
+ NoElements,
+
+ /// Iterator with one element, so the minimum and maximum are the same
+ OneElement(T),
+
+ /// More than one element in the iterator, the first element is not larger
+ /// than the second
+ MinMax(T, T)
+}
+
+impl<T: Clone> MinMaxResult<T> {
+ /// `into_option` creates an `Option` of type `(T, T)`. The returned `Option`
+ /// has variant `None` if and only if the `MinMaxResult` has variant
+ /// `NoElements`. Otherwise `Some((x, y))` is returned where `x <= y`.
+ /// If the `MinMaxResult` has variant `OneElement(x)`, performing this
+ /// operation will make one clone of `x`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use itertools::MinMaxResult::{self, NoElements, OneElement, MinMax};
+ ///
+ /// let r: MinMaxResult<i32> = NoElements;
+ /// assert_eq!(r.into_option(), None);
+ ///
+ /// let r = OneElement(1);
+ /// assert_eq!(r.into_option(), Some((1, 1)));
+ ///
+ /// let r = MinMax(1, 2);
+ /// assert_eq!(r.into_option(), Some((1, 2)));
+ /// ```
+ pub fn into_option(self) -> Option<(T,T)> {
+ match self {
+ MinMaxResult::NoElements => None,
+ MinMaxResult::OneElement(x) => Some((x.clone(), x)),
+ MinMaxResult::MinMax(x, y) => Some((x, y))
+ }
+ }
+}
+
+/// Implementation guts for `minmax` and `minmax_by_key`.
+pub fn minmax_impl<I, K, F, L>(mut it: I, mut key_for: F,
+ mut lt: L) -> MinMaxResult<I::Item>
+ where I: Iterator,
+ F: FnMut(&I::Item) -> K,
+ L: FnMut(&I::Item, &I::Item, &K, &K) -> bool,
+{
+ let (mut min, mut max, mut min_key, mut max_key) = match it.next() {
+ None => return MinMaxResult::NoElements,
+ Some(x) => {
+ match it.next() {
+ None => return MinMaxResult::OneElement(x),
+ Some(y) => {
+ let xk = key_for(&x);
+ let yk = key_for(&y);
+ if !lt(&y, &x, &yk, &xk) {(x, y, xk, yk)} else {(y, x, yk, xk)}
+ }
+ }
+ }
+ };
+
+ loop {
+ // `first` and `second` are the two next elements we want to look
+ // at. We first compare `first` and `second` (#1). The smaller one
+ // is then compared to current minimum (#2). The larger one is
+ // compared to current maximum (#3). This way we do 3 comparisons
+ // for 2 elements.
+ let first = match it.next() {
+ None => break,
+ Some(x) => x
+ };
+ let second = match it.next() {
+ None => {
+ let first_key = key_for(&first);
+ if lt(&first, &min, &first_key, &min_key) {
+ min = first;
+ } else if !lt(&first, &max, &first_key, &max_key) {
+ max = first;
+ }
+ break;
+ }
+ Some(x) => x
+ };
+ let first_key = key_for(&first);
+ let second_key = key_for(&second);
+ if !lt(&second, &first, &second_key, &first_key) {
+ if lt(&first, &min, &first_key, &min_key) {
+ min = first;
+ min_key = first_key;
+ }
+ if !lt(&second, &max, &second_key, &max_key) {
+ max = second;
+ max_key = second_key;
+ }
+ } else {
+ if lt(&second, &min, &second_key, &min_key) {
+ min = second;
+ min_key = second_key;
+ }
+ if !lt(&first, &max, &first_key, &max_key) {
+ max = first;
+ max_key = first_key;
+ }
+ }
+ }
+
+ MinMaxResult::MinMax(min, max)
+}
--- /dev/null
+use std::iter::Fuse;
+use alloc::collections::VecDeque;
+use crate::size_hint;
+use crate::PeekingNext;
+#[cfg(doc)]
+use crate::Itertools;
+
+/// See [`multipeek()`] for more information.
+#[derive(Clone, Debug)]
+pub struct MultiPeek<I>
+ where I: Iterator
+{
+ iter: Fuse<I>,
+ buf: VecDeque<I::Item>,
+ index: usize,
+}
+
+/// An iterator adaptor that allows the user to peek at multiple `.next()`
+/// values without advancing the base iterator.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::multipeek`].
+pub fn multipeek<I>(iterable: I) -> MultiPeek<I::IntoIter>
+ where I: IntoIterator
+{
+ MultiPeek {
+ iter: iterable.into_iter().fuse(),
+ buf: VecDeque::new(),
+ index: 0,
+ }
+}
+
+impl<I> MultiPeek<I>
+ where I: Iterator
+{
+ /// Reset the peeking “cursor”
+ pub fn reset_peek(&mut self) {
+ self.index = 0;
+ }
+}
+
+impl<I: Iterator> MultiPeek<I> {
+ /// Works exactly like `.next()` with the only difference that it doesn't
+ /// advance itself. `.peek()` can be called multiple times, to peek
+ /// further ahead.
+ /// When `.next()` is called, reset the peeking “cursor”.
+ pub fn peek(&mut self) -> Option<&I::Item> {
+ let ret = if self.index < self.buf.len() {
+ Some(&self.buf[self.index])
+ } else {
+ match self.iter.next() {
+ Some(x) => {
+ self.buf.push_back(x);
+ Some(&self.buf[self.index])
+ }
+ None => return None,
+ }
+ };
+
+ self.index += 1;
+ ret
+ }
+}
+
+impl<I> PeekingNext for MultiPeek<I>
+ where I: Iterator,
+{
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool
+ {
+ if self.buf.is_empty() {
+ if let Some(r) = self.peek() {
+ if !accept(r) { return None }
+ }
+ } else if let Some(r) = self.buf.get(0) {
+ if !accept(r) { return None }
+ }
+ self.next()
+ }
+}
+
+impl<I> Iterator for MultiPeek<I>
+ where I: Iterator
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.index = 0;
+ self.buf.pop_front().or_else(|| self.iter.next())
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add_scalar(self.iter.size_hint(), self.buf.len())
+ }
+}
+
+// Same size
+impl<I> ExactSizeIterator for MultiPeek<I>
+ where I: ExactSizeIterator
+{}
+
+
--- /dev/null
+use std::iter::{Fuse, FusedIterator};
+use crate::size_hint;
+
+/// An iterator adaptor that pads a sequence to a minimum length by filling
+/// missing elements using a closure.
+///
+/// Iterator element type is `I::Item`.
+///
+/// See [`.pad_using()`](crate::Itertools::pad_using) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct PadUsing<I, F> {
+ iter: Fuse<I>,
+ min: usize,
+ pos: usize,
+ filler: F,
+}
+
+impl<I, F> std::fmt::Debug for PadUsing<I, F>
+where
+ I: std::fmt::Debug,
+{
+ debug_fmt_fields!(PadUsing, iter, min, pos);
+}
+
+/// Create a new `PadUsing` iterator.
+pub fn pad_using<I, F>(iter: I, min: usize, filler: F) -> PadUsing<I, F>
+ where I: Iterator,
+ F: FnMut(usize) -> I::Item
+{
+ PadUsing {
+ iter: iter.fuse(),
+ min,
+ pos: 0,
+ filler,
+ }
+}
+
+impl<I, F> Iterator for PadUsing<I, F>
+ where I: Iterator,
+ F: FnMut(usize) -> I::Item
+{
+ type Item = I::Item;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.iter.next() {
+ None => {
+ if self.pos < self.min {
+ let e = Some((self.filler)(self.pos));
+ self.pos += 1;
+ e
+ } else {
+ None
+ }
+ },
+ e => {
+ self.pos += 1;
+ e
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let tail = self.min.saturating_sub(self.pos);
+ size_hint::max(self.iter.size_hint(), (tail, Some(tail)))
+ }
+}
+
+impl<I, F> DoubleEndedIterator for PadUsing<I, F>
+ where I: DoubleEndedIterator + ExactSizeIterator,
+ F: FnMut(usize) -> I::Item
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ if self.min == 0 {
+ self.iter.next_back()
+ } else if self.iter.len() >= self.min {
+ self.min -= 1;
+ self.iter.next_back()
+ } else {
+ self.min -= 1;
+ Some((self.filler)(self.min))
+ }
+ }
+}
+
+impl<I, F> ExactSizeIterator for PadUsing<I, F>
+ where I: ExactSizeIterator,
+ F: FnMut(usize) -> I::Item
+{}
+
+
+impl<I, F> FusedIterator for PadUsing<I, F>
+ where I: FusedIterator,
+ F: FnMut(usize) -> I::Item
+{}
--- /dev/null
+use crate::size_hint;
+use crate::PeekingNext;
+use alloc::collections::VecDeque;
+use std::iter::Fuse;
+
+/// See [`peek_nth()`] for more information.
+#[derive(Clone, Debug)]
+pub struct PeekNth<I>
+where
+ I: Iterator,
+{
+ iter: Fuse<I>,
+ buf: VecDeque<I::Item>,
+}
+
+/// A drop-in replacement for [`std::iter::Peekable`] which adds a `peek_nth`
+/// method allowing the user to `peek` at a value several iterations forward
+/// without advancing the base iterator.
+///
+/// This differs from `multipeek` in that subsequent calls to `peek` or
+/// `peek_nth` will always return the same value until `next` is called
+/// (making `reset_peek` unnecessary).
+pub fn peek_nth<I>(iterable: I) -> PeekNth<I::IntoIter>
+where
+ I: IntoIterator,
+{
+ PeekNth {
+ iter: iterable.into_iter().fuse(),
+ buf: VecDeque::new(),
+ }
+}
+
+impl<I> PeekNth<I>
+where
+ I: Iterator,
+{
+ /// Works exactly like the `peek` method in `std::iter::Peekable`
+ pub fn peek(&mut self) -> Option<&I::Item> {
+ self.peek_nth(0)
+ }
+
+ /// Returns a reference to the `nth` value without advancing the iterator.
+ ///
+ /// # Examples
+ ///
+ /// Basic usage:
+ ///
+ /// ```rust
+ /// use itertools::peek_nth;
+ ///
+ /// let xs = vec![1,2,3];
+ /// let mut iter = peek_nth(xs.iter());
+ ///
+ /// assert_eq!(iter.peek_nth(0), Some(&&1));
+ /// assert_eq!(iter.next(), Some(&1));
+ ///
+ /// // The iterator does not advance even if we call `peek_nth` multiple times
+ /// assert_eq!(iter.peek_nth(0), Some(&&2));
+ /// assert_eq!(iter.peek_nth(1), Some(&&3));
+ /// assert_eq!(iter.next(), Some(&2));
+ ///
+ /// // Calling `peek_nth` past the end of the iterator will return `None`
+ /// assert_eq!(iter.peek_nth(1), None);
+ /// ```
+ pub fn peek_nth(&mut self, n: usize) -> Option<&I::Item> {
+ let unbuffered_items = (n + 1).saturating_sub(self.buf.len());
+
+ self.buf.extend(self.iter.by_ref().take(unbuffered_items));
+
+ self.buf.get(n)
+ }
+}
+
+impl<I> Iterator for PeekNth<I>
+where
+ I: Iterator,
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.buf.pop_front().or_else(|| self.iter.next())
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add_scalar(self.iter.size_hint(), self.buf.len())
+ }
+}
+
+impl<I> ExactSizeIterator for PeekNth<I> where I: ExactSizeIterator {}
+
+impl<I> PeekingNext for PeekNth<I>
+where
+ I: Iterator,
+{
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where
+ F: FnOnce(&Self::Item) -> bool,
+ {
+ self.peek().filter(|item| accept(item))?;
+ self.next()
+ }
+}
--- /dev/null
+use std::iter::Peekable;
+use crate::PutBack;
+#[cfg(feature = "use_alloc")]
+use crate::PutBackN;
+
+/// An iterator that allows peeking at an element before deciding to accept it.
+///
+/// See [`.peeking_take_while()`](crate::Itertools::peeking_take_while)
+/// for more information.
+///
+/// This is implemented by peeking adaptors like peekable and put back,
+/// but also by a few iterators that can be peeked natively, like the slice’s
+/// by reference iterator (`std::slice::Iter`).
+pub trait PeekingNext : Iterator {
+ /// Pass a reference to the next iterator element to the closure `accept`;
+ /// if `accept` returns true, return it as the next element,
+ /// else None.
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool;
+}
+
+impl<I> PeekingNext for Peekable<I>
+ where I: Iterator,
+{
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool
+ {
+ if let Some(r) = self.peek() {
+ if !accept(r) {
+ return None;
+ }
+ }
+ self.next()
+ }
+}
+
+impl<I> PeekingNext for PutBack<I>
+ where I: Iterator,
+{
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool
+ {
+ if let Some(r) = self.next() {
+ if !accept(&r) {
+ self.put_back(r);
+ return None;
+ }
+ Some(r)
+ } else {
+ None
+ }
+ }
+}
+
+#[cfg(feature = "use_alloc")]
+impl<I> PeekingNext for PutBackN<I>
+ where I: Iterator,
+{
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool
+ {
+ if let Some(r) = self.next() {
+ if !accept(&r) {
+ self.put_back(r);
+ return None;
+ }
+ Some(r)
+ } else {
+ None
+ }
+ }
+}
+
+/// An iterator adaptor that takes items while a closure returns `true`.
+///
+/// See [`.peeking_take_while()`](crate::Itertools::peeking_take_while)
+/// for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct PeekingTakeWhile<'a, I: 'a, F>
+ where I: Iterator,
+{
+ iter: &'a mut I,
+ f: F,
+}
+
+impl<'a, I: 'a, F> std::fmt::Debug for PeekingTakeWhile<'a, I, F>
+where
+ I: Iterator + std::fmt::Debug,
+{
+ debug_fmt_fields!(PeekingTakeWhile, iter);
+}
+
+/// Create a `PeekingTakeWhile`
+pub fn peeking_take_while<I, F>(iter: &mut I, f: F) -> PeekingTakeWhile<I, F>
+ where I: Iterator,
+{
+ PeekingTakeWhile {
+ iter,
+ f,
+ }
+}
+
+impl<'a, I, F> Iterator for PeekingTakeWhile<'a, I, F>
+ where I: PeekingNext,
+ F: FnMut(&I::Item) -> bool,
+
+{
+ type Item = I::Item;
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.peeking_next(&mut self.f)
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+}
+
+// Some iterators are so lightweight we can simply clone them to save their
+// state and use that for peeking.
+macro_rules! peeking_next_by_clone {
+ ([$($typarm:tt)*] $type_:ty) => {
+ impl<$($typarm)*> PeekingNext for $type_ {
+ fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item>
+ where F: FnOnce(&Self::Item) -> bool
+ {
+ let saved_state = self.clone();
+ if let Some(r) = self.next() {
+ if !accept(&r) {
+ *self = saved_state;
+ } else {
+ return Some(r)
+ }
+ }
+ None
+ }
+ }
+ }
+}
+
+peeking_next_by_clone! { ['a, T] ::std::slice::Iter<'a, T> }
+peeking_next_by_clone! { ['a] ::std::str::Chars<'a> }
+peeking_next_by_clone! { ['a] ::std::str::CharIndices<'a> }
+peeking_next_by_clone! { ['a] ::std::str::Bytes<'a> }
+peeking_next_by_clone! { ['a, T] ::std::option::Iter<'a, T> }
+peeking_next_by_clone! { ['a, T] ::std::result::Iter<'a, T> }
+peeking_next_by_clone! { [T] ::std::iter::Empty<T> }
+#[cfg(feature = "use_alloc")]
+peeking_next_by_clone! { ['a, T] alloc::collections::linked_list::Iter<'a, T> }
+#[cfg(feature = "use_alloc")]
+peeking_next_by_clone! { ['a, T] alloc::collections::vec_deque::Iter<'a, T> }
+
+// cloning a Rev has no extra overhead; peekable and put backs are never DEI.
+peeking_next_by_clone! { [I: Clone + PeekingNext + DoubleEndedIterator]
+ ::std::iter::Rev<I> }
--- /dev/null
+use alloc::vec::Vec;
+use std::fmt;
+use std::iter::once;
+
+use super::lazy_buffer::LazyBuffer;
+
+/// An iterator adaptor that iterates through all the `k`-permutations of the
+/// elements from an iterator.
+///
+/// See [`.permutations()`](crate::Itertools::permutations) for
+/// more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Permutations<I: Iterator> {
+ vals: LazyBuffer<I>,
+ state: PermutationState,
+}
+
+impl<I> Clone for Permutations<I>
+ where I: Clone + Iterator,
+ I::Item: Clone,
+{
+ clone_fields!(vals, state);
+}
+
+#[derive(Clone, Debug)]
+enum PermutationState {
+ StartUnknownLen {
+ k: usize,
+ },
+ OngoingUnknownLen {
+ k: usize,
+ min_n: usize,
+ },
+ Complete(CompleteState),
+ Empty,
+}
+
+#[derive(Clone, Debug)]
+enum CompleteState {
+ Start {
+ n: usize,
+ k: usize,
+ },
+ Ongoing {
+ indices: Vec<usize>,
+ cycles: Vec<usize>,
+ }
+}
+
+enum CompleteStateRemaining {
+ Known(usize),
+ Overflow,
+}
+
+impl<I> fmt::Debug for Permutations<I>
+ where I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug,
+{
+ debug_fmt_fields!(Permutations, vals, state);
+}
+
+pub fn permutations<I: Iterator>(iter: I, k: usize) -> Permutations<I> {
+ let mut vals = LazyBuffer::new(iter);
+
+ if k == 0 {
+ // Special case, yields single empty vec; `n` is irrelevant
+ let state = PermutationState::Complete(CompleteState::Start { n: 0, k: 0 });
+
+ return Permutations {
+ vals,
+ state
+ };
+ }
+
+ let mut enough_vals = true;
+
+ while vals.len() < k {
+ if !vals.get_next() {
+ enough_vals = false;
+ break;
+ }
+ }
+
+ let state = if enough_vals {
+ PermutationState::StartUnknownLen { k }
+ } else {
+ PermutationState::Empty
+ };
+
+ Permutations {
+ vals,
+ state
+ }
+}
+
+impl<I> Iterator for Permutations<I>
+where
+ I: Iterator,
+ I::Item: Clone
+{
+ type Item = Vec<I::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.advance();
+
+ let &mut Permutations { ref vals, ref state } = self;
+
+ match *state {
+ PermutationState::StartUnknownLen { .. } => panic!("unexpected iterator state"),
+ PermutationState::OngoingUnknownLen { k, min_n } => {
+ let latest_idx = min_n - 1;
+ let indices = (0..(k - 1)).chain(once(latest_idx));
+
+ Some(indices.map(|i| vals[i].clone()).collect())
+ }
+ PermutationState::Complete(CompleteState::Ongoing { ref indices, ref cycles }) => {
+ let k = cycles.len();
+ Some(indices[0..k].iter().map(|&i| vals[i].clone()).collect())
+ },
+ PermutationState::Complete(CompleteState::Start { .. }) | PermutationState::Empty => None
+ }
+ }
+
+ fn count(self) -> usize {
+ fn from_complete(complete_state: CompleteState) -> usize {
+ match complete_state.remaining() {
+ CompleteStateRemaining::Known(count) => count,
+ CompleteStateRemaining::Overflow => {
+ panic!("Iterator count greater than usize::MAX");
+ }
+ }
+ }
+
+ let Permutations { vals, state } = self;
+ match state {
+ PermutationState::StartUnknownLen { k } => {
+ let n = vals.len() + vals.it.count();
+ let complete_state = CompleteState::Start { n, k };
+
+ from_complete(complete_state)
+ }
+ PermutationState::OngoingUnknownLen { k, min_n } => {
+ let prev_iteration_count = min_n - k + 1;
+ let n = vals.len() + vals.it.count();
+ let complete_state = CompleteState::Start { n, k };
+
+ from_complete(complete_state) - prev_iteration_count
+ },
+ PermutationState::Complete(state) => from_complete(state),
+ PermutationState::Empty => 0
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ match self.state {
+ PermutationState::StartUnknownLen { .. } |
+ PermutationState::OngoingUnknownLen { .. } => (0, None), // TODO can we improve this lower bound?
+ PermutationState::Complete(ref state) => match state.remaining() {
+ CompleteStateRemaining::Known(count) => (count, Some(count)),
+ CompleteStateRemaining::Overflow => (::std::usize::MAX, None)
+ }
+ PermutationState::Empty => (0, Some(0))
+ }
+ }
+}
+
+impl<I> Permutations<I>
+where
+ I: Iterator,
+ I::Item: Clone
+{
+ fn advance(&mut self) {
+ let &mut Permutations { ref mut vals, ref mut state } = self;
+
+ *state = match *state {
+ PermutationState::StartUnknownLen { k } => {
+ PermutationState::OngoingUnknownLen { k, min_n: k }
+ }
+ PermutationState::OngoingUnknownLen { k, min_n } => {
+ if vals.get_next() {
+ PermutationState::OngoingUnknownLen { k, min_n: min_n + 1 }
+ } else {
+ let n = min_n;
+ let prev_iteration_count = n - k + 1;
+ let mut complete_state = CompleteState::Start { n, k };
+
+ // Advance the complete-state iterator to the correct point
+ for _ in 0..(prev_iteration_count + 1) {
+ complete_state.advance();
+ }
+
+ PermutationState::Complete(complete_state)
+ }
+ }
+ PermutationState::Complete(ref mut state) => {
+ state.advance();
+
+ return;
+ }
+ PermutationState::Empty => { return; }
+ };
+ }
+}
+
+impl CompleteState {
+ fn advance(&mut self) {
+ *self = match *self {
+ CompleteState::Start { n, k } => {
+ let indices = (0..n).collect();
+ let cycles = ((n - k)..n).rev().collect();
+
+ CompleteState::Ongoing {
+ cycles,
+ indices
+ }
+ },
+ CompleteState::Ongoing { ref mut indices, ref mut cycles } => {
+ let n = indices.len();
+ let k = cycles.len();
+
+ for i in (0..k).rev() {
+ if cycles[i] == 0 {
+ cycles[i] = n - i - 1;
+
+ let to_push = indices.remove(i);
+ indices.push(to_push);
+ } else {
+ let swap_index = n - cycles[i];
+ indices.swap(i, swap_index);
+
+ cycles[i] -= 1;
+ return;
+ }
+ }
+
+ CompleteState::Start { n, k }
+ }
+ }
+ }
+
+ fn remaining(&self) -> CompleteStateRemaining {
+ use self::CompleteStateRemaining::{Known, Overflow};
+
+ match *self {
+ CompleteState::Start { n, k } => {
+ if n < k {
+ return Known(0);
+ }
+
+ let count: Option<usize> = (n - k + 1..n + 1).fold(Some(1), |acc, i| {
+ acc.and_then(|acc| acc.checked_mul(i))
+ });
+
+ match count {
+ Some(count) => Known(count),
+ None => Overflow
+ }
+ }
+ CompleteState::Ongoing { ref indices, ref cycles } => {
+ let mut count: usize = 0;
+
+ for (i, &c) in cycles.iter().enumerate() {
+ let radix = indices.len() - i;
+ let next_count = count.checked_mul(radix)
+ .and_then(|count| count.checked_add(c));
+
+ count = match next_count {
+ Some(count) => count,
+ None => { return Overflow; }
+ };
+ }
+
+ Known(count)
+ }
+ }
+ }
+}
--- /dev/null
+use std::fmt;
+use std::iter::FusedIterator;
+use std::usize;
+use alloc::vec::Vec;
+
+use super::combinations::{Combinations, combinations};
+use super::size_hint;
+
+/// An iterator to iterate through the powerset of the elements from an iterator.
+///
+/// See [`.powerset()`](crate::Itertools::powerset) for more
+/// information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Powerset<I: Iterator> {
+ combs: Combinations<I>,
+ // Iterator `position` (equal to count of yielded elements).
+ pos: usize,
+}
+
+impl<I> Clone for Powerset<I>
+ where I: Clone + Iterator,
+ I::Item: Clone,
+{
+ clone_fields!(combs, pos);
+}
+
+impl<I> fmt::Debug for Powerset<I>
+ where I: Iterator + fmt::Debug,
+ I::Item: fmt::Debug,
+{
+ debug_fmt_fields!(Powerset, combs, pos);
+}
+
+/// Create a new `Powerset` from a clonable iterator.
+pub fn powerset<I>(src: I) -> Powerset<I>
+ where I: Iterator,
+ I::Item: Clone,
+{
+ Powerset {
+ combs: combinations(src, 0),
+ pos: 0,
+ }
+}
+
+impl<I> Iterator for Powerset<I>
+ where
+ I: Iterator,
+ I::Item: Clone,
+{
+ type Item = Vec<I::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if let Some(elt) = self.combs.next() {
+ self.pos = self.pos.saturating_add(1);
+ Some(elt)
+ } else if self.combs.k() < self.combs.n()
+ || self.combs.k() == 0
+ {
+ self.combs.reset(self.combs.k() + 1);
+ self.combs.next().map(|elt| {
+ self.pos = self.pos.saturating_add(1);
+ elt
+ })
+ } else {
+ None
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // Total bounds for source iterator.
+ let src_total = size_hint::add_scalar(self.combs.src().size_hint(), self.combs.n());
+
+ // Total bounds for self ( length(powerset(set) == 2 ^ length(set) )
+ let self_total = size_hint::pow_scalar_base(2, src_total);
+
+ if self.pos < usize::MAX {
+ // Subtract count of elements already yielded from total.
+ size_hint::sub_scalar(self_total, self.pos)
+ } else {
+ // Fallback: self.pos is saturated and no longer reliable.
+ (0, self_total.1)
+ }
+ }
+}
+
+impl<I> FusedIterator for Powerset<I>
+ where
+ I: Iterator,
+ I::Item: Clone,
+{}
--- /dev/null
+
+/// An iterator that produces only the `T` values as long as the
+/// inner iterator produces `Ok(T)`.
+///
+/// Used by [`process_results`](crate::process_results), see its docs
+/// for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug)]
+pub struct ProcessResults<'a, I, E: 'a> {
+ error: &'a mut Result<(), E>,
+ iter: I,
+}
+
+impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E>
+ where I: Iterator<Item = Result<T, E>>
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.iter.next() {
+ Some(Ok(x)) => Some(x),
+ Some(Err(e)) => {
+ *self.error = Err(e);
+ None
+ }
+ None => None,
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (0, self.iter.size_hint().1)
+ }
+
+ fn fold<B, F>(mut self, init: B, mut f: F) -> B
+ where
+ Self: Sized,
+ F: FnMut(B, Self::Item) -> B,
+ {
+ let error = self.error;
+ self.iter
+ .try_fold(init, |acc, opt| match opt {
+ Ok(x) => Ok(f(acc, x)),
+ Err(e) => {
+ *error = Err(e);
+ Err(acc)
+ }
+ })
+ .unwrap_or_else(|e| e)
+ }
+}
+
+/// “Lift” a function of the values of an iterator so that it can process
+/// an iterator of `Result` values instead.
+///
+/// `iterable` is an iterator or iterable with `Result<T, E>` elements, where
+/// `T` is the value type and `E` the error type.
+///
+/// `processor` is a closure that receives an adapted version of the iterable
+/// as the only argument — the adapted iterator produces elements of type `T`,
+/// as long as the original iterator produces `Ok` values.
+///
+/// If the original iterable produces an error at any point, the adapted
+/// iterator ends and the `process_results` function will return the
+/// error iself.
+///
+/// Otherwise, the return value from the closure is returned wrapped
+/// inside `Ok`.
+///
+/// # Example
+///
+/// ```
+/// use itertools::process_results;
+///
+/// type R = Result<i32, &'static str>;
+///
+/// let first_values: Vec<R> = vec![Ok(1), Ok(0), Ok(3)];
+/// let second_values: Vec<R> = vec![Ok(2), Ok(1), Err("overflow")];
+///
+/// // “Lift” the iterator .max() method to work on the values in Results using process_results
+///
+/// let first_max = process_results(first_values, |iter| iter.max().unwrap_or(0));
+/// let second_max = process_results(second_values, |iter| iter.max().unwrap_or(0));
+///
+/// assert_eq!(first_max, Ok(3));
+/// assert!(second_max.is_err());
+/// ```
+pub fn process_results<I, F, T, E, R>(iterable: I, processor: F) -> Result<R, E>
+ where I: IntoIterator<Item = Result<T, E>>,
+ F: FnOnce(ProcessResults<I::IntoIter, E>) -> R
+{
+ let iter = iterable.into_iter();
+ let mut error = Ok(());
+
+ let result = processor(ProcessResults { error: &mut error, iter });
+
+ error.map(|_| result)
+}
--- /dev/null
+use alloc::vec::Vec;
+
+use crate::size_hint;
+
+/// An iterator adaptor that allows putting multiple
+/// items in front of the iterator.
+///
+/// Iterator element type is `I::Item`.
+#[derive(Debug, Clone)]
+pub struct PutBackN<I: Iterator> {
+ top: Vec<I::Item>,
+ iter: I,
+}
+
+/// Create an iterator where you can put back multiple values to the front
+/// of the iteration.
+///
+/// Iterator element type is `I::Item`.
+pub fn put_back_n<I>(iterable: I) -> PutBackN<I::IntoIter>
+ where I: IntoIterator
+{
+ PutBackN {
+ top: Vec::new(),
+ iter: iterable.into_iter(),
+ }
+}
+
+impl<I: Iterator> PutBackN<I> {
+ /// Puts x in front of the iterator.
+ /// The values are yielded in order of the most recently put back
+ /// values first.
+ ///
+ /// ```rust
+ /// use itertools::put_back_n;
+ ///
+ /// let mut it = put_back_n(1..5);
+ /// it.next();
+ /// it.put_back(1);
+ /// it.put_back(0);
+ ///
+ /// assert!(itertools::equal(it, 0..5));
+ /// ```
+ #[inline]
+ pub fn put_back(&mut self, x: I::Item) {
+ self.top.push(x);
+ }
+}
+
+impl<I: Iterator> Iterator for PutBackN<I> {
+ type Item = I::Item;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.top.pop().or_else(|| self.iter.next())
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::add_scalar(self.iter.size_hint(), self.top.len())
+ }
+}
+
--- /dev/null
+
+use std::iter::{FusedIterator, IntoIterator};
+use alloc::rc::Rc;
+use std::cell::RefCell;
+
+/// A wrapper for `Rc<RefCell<I>>`, that implements the `Iterator` trait.
+#[derive(Debug)]
+pub struct RcIter<I> {
+ /// The boxed iterator.
+ pub rciter: Rc<RefCell<I>>,
+}
+
+/// Return an iterator inside a `Rc<RefCell<_>>` wrapper.
+///
+/// The returned `RcIter` can be cloned, and each clone will refer back to the
+/// same original iterator.
+///
+/// `RcIter` allows doing interesting things like using `.zip()` on an iterator with
+/// itself, at the cost of runtime borrow checking which may have a performance
+/// penalty.
+///
+/// Iterator element type is `Self::Item`.
+///
+/// ```
+/// use itertools::rciter;
+/// use itertools::zip;
+///
+/// // In this example a range iterator is created and we iterate it using
+/// // three separate handles (two of them given to zip).
+/// // We also use the IntoIterator implementation for `&RcIter`.
+///
+/// let mut iter = rciter(0..9);
+/// let mut z = zip(&iter, &iter);
+///
+/// assert_eq!(z.next(), Some((0, 1)));
+/// assert_eq!(z.next(), Some((2, 3)));
+/// assert_eq!(z.next(), Some((4, 5)));
+/// assert_eq!(iter.next(), Some(6));
+/// assert_eq!(z.next(), Some((7, 8)));
+/// assert_eq!(z.next(), None);
+/// ```
+///
+/// **Panics** in iterator methods if a borrow error is encountered in the
+/// iterator methods. It can only happen if the `RcIter` is reentered in
+/// `.next()`, i.e. if it somehow participates in an “iterator knot”
+/// where it is an adaptor of itself.
+pub fn rciter<I>(iterable: I) -> RcIter<I::IntoIter>
+ where I: IntoIterator
+{
+ RcIter { rciter: Rc::new(RefCell::new(iterable.into_iter())) }
+}
+
+impl<I> Clone for RcIter<I> {
+ clone_fields!(rciter);
+}
+
+impl<A, I> Iterator for RcIter<I>
+ where I: Iterator<Item = A>
+{
+ type Item = A;
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.rciter.borrow_mut().next()
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ // To work sanely with other API that assume they own an iterator,
+ // so it can't change in other places, we can't guarantee as much
+ // in our size_hint. Other clones may drain values under our feet.
+ (0, self.rciter.borrow().size_hint().1)
+ }
+}
+
+impl<I> DoubleEndedIterator for RcIter<I>
+ where I: DoubleEndedIterator
+{
+ #[inline]
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.rciter.borrow_mut().next_back()
+ }
+}
+
+/// Return an iterator from `&RcIter<I>` (by simply cloning it).
+impl<'a, I> IntoIterator for &'a RcIter<I>
+ where I: Iterator
+{
+ type Item = I::Item;
+ type IntoIter = RcIter<I>;
+
+ fn into_iter(self) -> RcIter<I> {
+ self.clone()
+ }
+}
+
+
+impl<A, I> FusedIterator for RcIter<I>
+ where I: FusedIterator<Item = A>
+{}
--- /dev/null
+use std::iter::FusedIterator;
+
+/// An iterator that produces *n* repetitions of an element.
+///
+/// See [`repeat_n()`](crate::repeat_n) for more information.
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+#[derive(Clone, Debug)]
+pub struct RepeatN<A> {
+ elt: Option<A>,
+ n: usize,
+}
+
+/// Create an iterator that produces `n` repetitions of `element`.
+pub fn repeat_n<A>(element: A, n: usize) -> RepeatN<A>
+ where A: Clone,
+{
+ if n == 0 {
+ RepeatN { elt: None, n, }
+ } else {
+ RepeatN { elt: Some(element), n, }
+ }
+}
+
+impl<A> Iterator for RepeatN<A>
+ where A: Clone
+{
+ type Item = A;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.n > 1 {
+ self.n -= 1;
+ self.elt.as_ref().cloned()
+ } else {
+ self.n = 0;
+ self.elt.take()
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.n, Some(self.n))
+ }
+}
+
+impl<A> DoubleEndedIterator for RepeatN<A>
+ where A: Clone
+{
+ #[inline]
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.next()
+ }
+}
+
+impl<A> ExactSizeIterator for RepeatN<A>
+ where A: Clone
+{}
+
+impl<A> FusedIterator for RepeatN<A>
+ where A: Clone
+{}
--- /dev/null
+//! Arithmetic on `Iterator.size_hint()` values.
+//!
+
+use std::usize;
+use std::cmp;
+use std::u32;
+
+/// `SizeHint` is the return type of `Iterator::size_hint()`.
+pub type SizeHint = (usize, Option<usize>);
+
+/// Add `SizeHint` correctly.
+#[inline]
+pub fn add(a: SizeHint, b: SizeHint) -> SizeHint {
+ let min = a.0.saturating_add(b.0);
+ let max = match (a.1, b.1) {
+ (Some(x), Some(y)) => x.checked_add(y),
+ _ => None,
+ };
+
+ (min, max)
+}
+
+/// Add `x` correctly to a `SizeHint`.
+#[inline]
+pub fn add_scalar(sh: SizeHint, x: usize) -> SizeHint {
+ let (mut low, mut hi) = sh;
+ low = low.saturating_add(x);
+ hi = hi.and_then(|elt| elt.checked_add(x));
+ (low, hi)
+}
+
+/// Subtract `x` correctly from a `SizeHint`.
+#[inline]
+#[allow(dead_code)]
+pub fn sub_scalar(sh: SizeHint, x: usize) -> SizeHint {
+ let (mut low, mut hi) = sh;
+ low = low.saturating_sub(x);
+ hi = hi.map(|elt| elt.saturating_sub(x));
+ (low, hi)
+}
+
+
+/// Multiply `SizeHint` correctly
+///
+/// ```ignore
+/// use std::usize;
+/// use itertools::size_hint;
+///
+/// assert_eq!(size_hint::mul((3, Some(4)), (3, Some(4))),
+/// (9, Some(16)));
+///
+/// assert_eq!(size_hint::mul((3, Some(4)), (usize::MAX, None)),
+/// (usize::MAX, None));
+///
+/// assert_eq!(size_hint::mul((3, None), (0, Some(0))),
+/// (0, Some(0)));
+/// ```
+#[inline]
+pub fn mul(a: SizeHint, b: SizeHint) -> SizeHint {
+ let low = a.0.saturating_mul(b.0);
+ let hi = match (a.1, b.1) {
+ (Some(x), Some(y)) => x.checked_mul(y),
+ (Some(0), None) | (None, Some(0)) => Some(0),
+ _ => None,
+ };
+ (low, hi)
+}
+
+/// Multiply `x` correctly with a `SizeHint`.
+#[inline]
+pub fn mul_scalar(sh: SizeHint, x: usize) -> SizeHint {
+ let (mut low, mut hi) = sh;
+ low = low.saturating_mul(x);
+ hi = hi.and_then(|elt| elt.checked_mul(x));
+ (low, hi)
+}
+
+/// Raise `base` correctly by a `SizeHint` exponent.
+#[inline]
+pub fn pow_scalar_base(base: usize, exp: SizeHint) -> SizeHint {
+ let exp_low = cmp::min(exp.0, u32::MAX as usize) as u32;
+ let low = base.saturating_pow(exp_low);
+
+ let hi = exp.1.and_then(|exp| {
+ let exp_hi = cmp::min(exp, u32::MAX as usize) as u32;
+ base.checked_pow(exp_hi)
+ });
+
+ (low, hi)
+}
+
+/// Return the maximum
+#[inline]
+pub fn max(a: SizeHint, b: SizeHint) -> SizeHint {
+ let (a_lower, a_upper) = a;
+ let (b_lower, b_upper) = b;
+
+ let lower = cmp::max(a_lower, b_lower);
+
+ let upper = match (a_upper, b_upper) {
+ (Some(x), Some(y)) => Some(cmp::max(x, y)),
+ _ => None,
+ };
+
+ (lower, upper)
+}
+
+/// Return the minimum
+#[inline]
+pub fn min(a: SizeHint, b: SizeHint) -> SizeHint {
+ let (a_lower, a_upper) = a;
+ let (b_lower, b_upper) = b;
+ let lower = cmp::min(a_lower, b_lower);
+ let upper = match (a_upper, b_upper) {
+ (Some(u1), Some(u2)) => Some(cmp::min(u1, u2)),
+ _ => a_upper.or(b_upper),
+ };
+ (lower, upper)
+}
--- /dev/null
+//! Iterators that are sources (produce elements from parameters,
+//! not from another iterator).
+#![allow(deprecated)]
+
+use std::fmt;
+use std::mem;
+
+/// See [`repeat_call`](crate::repeat_call) for more information.
+#[derive(Clone)]
+#[deprecated(note="Use std repeat_with() instead", since="0.8.0")]
+pub struct RepeatCall<F> {
+ f: F,
+}
+
+impl<F> fmt::Debug for RepeatCall<F>
+{
+ debug_fmt_fields!(RepeatCall, );
+}
+
+/// An iterator source that produces elements indefinitely by calling
+/// a given closure.
+///
+/// Iterator element type is the return type of the closure.
+///
+/// ```
+/// use itertools::repeat_call;
+/// use itertools::Itertools;
+/// use std::collections::BinaryHeap;
+///
+/// let mut heap = BinaryHeap::from(vec![2, 5, 3, 7, 8]);
+///
+/// // extract each element in sorted order
+/// for element in repeat_call(|| heap.pop()).while_some() {
+/// print!("{}", element);
+/// }
+///
+/// itertools::assert_equal(
+/// repeat_call(|| 1).take(5),
+/// vec![1, 1, 1, 1, 1]
+/// );
+/// ```
+#[deprecated(note="Use std repeat_with() instead", since="0.8.0")]
+pub fn repeat_call<F, A>(function: F) -> RepeatCall<F>
+ where F: FnMut() -> A
+{
+ RepeatCall { f: function }
+}
+
+impl<A, F> Iterator for RepeatCall<F>
+ where F: FnMut() -> A
+{
+ type Item = A;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ Some((self.f)())
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (usize::max_value(), None)
+ }
+}
+
+/// Creates a new unfold source with the specified closure as the "iterator
+/// function" and an initial state to eventually pass to the closure
+///
+/// `unfold` is a general iterator builder: it has a mutable state value,
+/// and a closure with access to the state that produces the next value.
+///
+/// This more or less equivalent to a regular struct with an [`Iterator`]
+/// implementation, and is useful for one-off iterators.
+///
+/// ```
+/// // an iterator that yields sequential Fibonacci numbers,
+/// // and stops at the maximum representable value.
+///
+/// use itertools::unfold;
+///
+/// let mut fibonacci = unfold((1u32, 1u32), |(x1, x2)| {
+/// // Attempt to get the next Fibonacci number
+/// let next = x1.saturating_add(*x2);
+///
+/// // Shift left: ret <- x1 <- x2 <- next
+/// let ret = *x1;
+/// *x1 = *x2;
+/// *x2 = next;
+///
+/// // If addition has saturated at the maximum, we are finished
+/// if ret == *x1 && ret > 1 {
+/// None
+/// } else {
+/// Some(ret)
+/// }
+/// });
+///
+/// itertools::assert_equal(fibonacci.by_ref().take(8),
+/// vec![1, 1, 2, 3, 5, 8, 13, 21]);
+/// assert_eq!(fibonacci.last(), Some(2_971_215_073))
+/// ```
+pub fn unfold<A, St, F>(initial_state: St, f: F) -> Unfold<St, F>
+ where F: FnMut(&mut St) -> Option<A>
+{
+ Unfold {
+ f,
+ state: initial_state,
+ }
+}
+
+impl<St, F> fmt::Debug for Unfold<St, F>
+ where St: fmt::Debug,
+{
+ debug_fmt_fields!(Unfold, state);
+}
+
+/// See [`unfold`](crate::unfold) for more information.
+#[derive(Clone)]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+pub struct Unfold<St, F> {
+ f: F,
+ /// Internal state that will be passed to the closure on the next iteration
+ pub state: St,
+}
+
+impl<A, St, F> Iterator for Unfold<St, F>
+ where F: FnMut(&mut St) -> Option<A>
+{
+ type Item = A;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ (self.f)(&mut self.state)
+ }
+}
+
+/// An iterator that infinitely applies function to value and yields results.
+///
+/// This `struct` is created by the [`iterate()`](crate::iterate) function.
+/// See its documentation for more.
+#[derive(Clone)]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
+pub struct Iterate<St, F> {
+ state: St,
+ f: F,
+}
+
+impl<St, F> fmt::Debug for Iterate<St, F>
+ where St: fmt::Debug,
+{
+ debug_fmt_fields!(Iterate, state);
+}
+
+impl<St, F> Iterator for Iterate<St, F>
+ where F: FnMut(&St) -> St
+{
+ type Item = St;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ let next_state = (self.f)(&self.state);
+ Some(mem::replace(&mut self.state, next_state))
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (usize::max_value(), None)
+ }
+}
+
+/// Creates a new iterator that infinitely applies function to value and yields results.
+///
+/// ```
+/// use itertools::iterate;
+///
+/// itertools::assert_equal(iterate(1, |&i| i * 3).take(5), vec![1, 3, 9, 27, 81]);
+/// ```
+pub fn iterate<St, F>(initial_value: St, f: F) -> Iterate<St, F>
+ where F: FnMut(&St) -> St
+{
+ Iterate {
+ state: initial_value,
+ f,
+ }
+}
--- /dev/null
+use super::size_hint;
+
+use std::cell::RefCell;
+use alloc::collections::VecDeque;
+use alloc::rc::Rc;
+
+/// Common buffer object for the two tee halves
+#[derive(Debug)]
+struct TeeBuffer<A, I> {
+ backlog: VecDeque<A>,
+ iter: I,
+ /// The owner field indicates which id should read from the backlog
+ owner: bool,
+}
+
+/// One half of an iterator pair where both return the same elements.
+///
+/// See [`.tee()`](crate::Itertools::tee) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug)]
+pub struct Tee<I>
+ where I: Iterator
+{
+ rcbuffer: Rc<RefCell<TeeBuffer<I::Item, I>>>,
+ id: bool,
+}
+
+pub fn new<I>(iter: I) -> (Tee<I>, Tee<I>)
+ where I: Iterator
+{
+ let buffer = TeeBuffer{backlog: VecDeque::new(), iter, owner: false};
+ let t1 = Tee{rcbuffer: Rc::new(RefCell::new(buffer)), id: true};
+ let t2 = Tee{rcbuffer: t1.rcbuffer.clone(), id: false};
+ (t1, t2)
+}
+
+impl<I> Iterator for Tee<I>
+ where I: Iterator,
+ I::Item: Clone
+{
+ type Item = I::Item;
+ fn next(&mut self) -> Option<Self::Item> {
+ // .borrow_mut may fail here -- but only if the user has tied some kind of weird
+ // knot where the iterator refers back to itself.
+ let mut buffer = self.rcbuffer.borrow_mut();
+ if buffer.owner == self.id {
+ match buffer.backlog.pop_front() {
+ None => {}
+ some_elt => return some_elt,
+ }
+ }
+ match buffer.iter.next() {
+ None => None,
+ Some(elt) => {
+ buffer.backlog.push_back(elt.clone());
+ buffer.owner = !self.id;
+ Some(elt)
+ }
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let buffer = self.rcbuffer.borrow();
+ let sh = buffer.iter.size_hint();
+
+ if buffer.owner == self.id {
+ let log_len = buffer.backlog.len();
+ size_hint::add_scalar(sh, log_len)
+ } else {
+ sh
+ }
+ }
+}
+
+impl<I> ExactSizeIterator for Tee<I>
+ where I: ExactSizeIterator,
+ I::Item: Clone
+{}
--- /dev/null
+//! Some iterator that produces tuples
+
+use std::iter::Fuse;
+use std::iter::FusedIterator;
+use std::iter::Take;
+use std::iter::Cycle;
+use std::marker::PhantomData;
+
+// `HomogeneousTuple` is a public facade for `TupleCollect`, allowing
+// tuple-related methods to be used by clients in generic contexts, while
+// hiding the implementation details of `TupleCollect`.
+// See https://github.com/rust-itertools/itertools/issues/387
+
+/// Implemented for homogeneous tuples of size up to 12.
+pub trait HomogeneousTuple
+ : TupleCollect
+{}
+
+impl<T: TupleCollect> HomogeneousTuple for T {}
+
+/// An iterator over a incomplete tuple.
+///
+/// See [`.tuples()`](crate::Itertools::tuples) and
+/// [`Tuples::into_buffer()`].
+#[derive(Clone, Debug)]
+pub struct TupleBuffer<T>
+ where T: HomogeneousTuple
+{
+ cur: usize,
+ buf: T::Buffer,
+}
+
+impl<T> TupleBuffer<T>
+ where T: HomogeneousTuple
+{
+ fn new(buf: T::Buffer) -> Self {
+ TupleBuffer {
+ cur: 0,
+ buf,
+ }
+ }
+}
+
+impl<T> Iterator for TupleBuffer<T>
+ where T: HomogeneousTuple
+{
+ type Item = T::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let s = self.buf.as_mut();
+ if let Some(ref mut item) = s.get_mut(self.cur) {
+ self.cur += 1;
+ item.take()
+ } else {
+ None
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let buffer = &self.buf.as_ref()[self.cur..];
+ let len = if buffer.is_empty() {
+ 0
+ } else {
+ buffer.iter()
+ .position(|x| x.is_none())
+ .unwrap_or_else(|| buffer.len())
+ };
+ (len, Some(len))
+ }
+}
+
+impl<T> ExactSizeIterator for TupleBuffer<T>
+ where T: HomogeneousTuple
+{
+}
+
+/// An iterator that groups the items in tuples of a specific size.
+///
+/// See [`.tuples()`](crate::Itertools::tuples) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Tuples<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple
+{
+ iter: Fuse<I>,
+ buf: T::Buffer,
+}
+
+/// Create a new tuples iterator.
+pub fn tuples<I, T>(iter: I) -> Tuples<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple
+{
+ Tuples {
+ iter: iter.fuse(),
+ buf: Default::default(),
+ }
+}
+
+impl<I, T> Iterator for Tuples<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ T::collect_from_iter(&mut self.iter, &mut self.buf)
+ }
+}
+
+impl<I, T> Tuples<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple
+{
+ /// Return a buffer with the produced items that was not enough to be grouped in a tuple.
+ ///
+ /// ```
+ /// use itertools::Itertools;
+ ///
+ /// let mut iter = (0..5).tuples();
+ /// assert_eq!(Some((0, 1, 2)), iter.next());
+ /// assert_eq!(None, iter.next());
+ /// itertools::assert_equal(vec![3, 4], iter.into_buffer());
+ /// ```
+ pub fn into_buffer(self) -> TupleBuffer<T> {
+ TupleBuffer::new(self.buf)
+ }
+}
+
+
+/// An iterator over all contiguous windows that produces tuples of a specific size.
+///
+/// See [`.tuple_windows()`](crate::Itertools::tuple_windows) for more
+/// information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Clone, Debug)]
+pub struct TupleWindows<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple
+{
+ iter: I,
+ last: Option<T>,
+}
+
+/// Create a new tuple windows iterator.
+pub fn tuple_windows<I, T>(mut iter: I) -> TupleWindows<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple,
+ T::Item: Clone
+{
+ use std::iter::once;
+
+ let mut last = None;
+ if T::num_items() != 1 {
+ // put in a duplicate item in front of the tuple; this simplifies
+ // .next() function.
+ if let Some(item) = iter.next() {
+ let iter = once(item.clone()).chain(once(item)).chain(&mut iter);
+ last = T::collect_from_iter_no_buf(iter);
+ }
+ }
+
+ TupleWindows {
+ iter,
+ last,
+ }
+}
+
+impl<I, T> Iterator for TupleWindows<I, T>
+ where I: Iterator<Item = T::Item>,
+ T: HomogeneousTuple + Clone,
+ T::Item: Clone
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if T::num_items() == 1 {
+ return T::collect_from_iter_no_buf(&mut self.iter)
+ }
+ if let Some(ref mut last) = self.last {
+ if let Some(new) = self.iter.next() {
+ last.left_shift_push(new);
+ return Some(last.clone());
+ }
+ }
+ None
+ }
+}
+
+impl<I, T> FusedIterator for TupleWindows<I, T>
+ where I: FusedIterator<Item = T::Item>,
+ T: HomogeneousTuple + Clone,
+ T::Item: Clone
+{}
+
+/// An iterator over all windows,wrapping back to the first elements when the
+/// window would otherwise exceed the length of the iterator, producing tuples
+/// of a specific size.
+///
+/// See [`.circular_tuple_windows()`](crate::Itertools::circular_tuple_windows) for more
+/// information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug)]
+pub struct CircularTupleWindows<I, T: Clone>
+ where I: Iterator<Item = T::Item> + Clone,
+ T: TupleCollect + Clone
+{
+ iter: Take<TupleWindows<Cycle<I>, T>>,
+ phantom_data: PhantomData<T>
+}
+
+pub fn circular_tuple_windows<I, T>(iter: I) -> CircularTupleWindows<I, T>
+ where I: Iterator<Item = T::Item> + Clone + ExactSizeIterator,
+ T: TupleCollect + Clone,
+ T::Item: Clone
+{
+ let len = iter.len();
+ let iter = tuple_windows(iter.cycle()).take(len);
+
+ CircularTupleWindows {
+ iter,
+ phantom_data: PhantomData{}
+ }
+}
+
+impl<I, T> Iterator for CircularTupleWindows<I, T>
+ where I: Iterator<Item = T::Item> + Clone,
+ T: TupleCollect + Clone,
+ T::Item: Clone
+{
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.iter.next()
+ }
+}
+
+pub trait TupleCollect: Sized {
+ type Item;
+ type Buffer: Default + AsRef<[Option<Self::Item>]> + AsMut<[Option<Self::Item>]>;
+
+ fn collect_from_iter<I>(iter: I, buf: &mut Self::Buffer) -> Option<Self>
+ where I: IntoIterator<Item = Self::Item>;
+
+ fn collect_from_iter_no_buf<I>(iter: I) -> Option<Self>
+ where I: IntoIterator<Item = Self::Item>;
+
+ fn num_items() -> usize;
+
+ fn left_shift_push(&mut self, item: Self::Item);
+}
+
+macro_rules! count_ident{
+ () => {0};
+ ($i0:ident, $($i:ident,)*) => {1 + count_ident!($($i,)*)};
+}
+macro_rules! rev_for_each_ident{
+ ($m:ident, ) => {};
+ ($m:ident, $i0:ident, $($i:ident,)*) => {
+ rev_for_each_ident!($m, $($i,)*);
+ $m!($i0);
+ };
+}
+
+macro_rules! impl_tuple_collect {
+ ($dummy:ident,) => {}; // stop
+ ($dummy:ident, $($Y:ident,)*) => (
+ impl_tuple_collect!($($Y,)*);
+ impl<A> TupleCollect for ($(ignore_ident!($Y, A),)*) {
+ type Item = A;
+ type Buffer = [Option<A>; count_ident!($($Y,)*) - 1];
+
+ #[allow(unused_assignments, unused_mut)]
+ fn collect_from_iter<I>(iter: I, buf: &mut Self::Buffer) -> Option<Self>
+ where I: IntoIterator<Item = A>
+ {
+ let mut iter = iter.into_iter();
+ $(
+ let mut $Y = None;
+ )*
+
+ loop {
+ $(
+ $Y = iter.next();
+ if $Y.is_none() {
+ break
+ }
+ )*
+ return Some(($($Y.unwrap()),*,))
+ }
+
+ let mut i = 0;
+ let mut s = buf.as_mut();
+ $(
+ if i < s.len() {
+ s[i] = $Y;
+ i += 1;
+ }
+ )*
+ return None;
+ }
+
+ fn collect_from_iter_no_buf<I>(iter: I) -> Option<Self>
+ where I: IntoIterator<Item = A>
+ {
+ let mut iter = iter.into_iter();
+
+ Some(($(
+ { let $Y = iter.next()?; $Y },
+ )*))
+ }
+
+ fn num_items() -> usize {
+ count_ident!($($Y,)*)
+ }
+
+ fn left_shift_push(&mut self, mut item: A) {
+ use std::mem::replace;
+
+ let &mut ($(ref mut $Y),*,) = self;
+ macro_rules! replace_item{($i:ident) => {
+ item = replace($i, item);
+ }}
+ rev_for_each_ident!(replace_item, $($Y,)*);
+ drop(item);
+ }
+ }
+ )
+}
+impl_tuple_collect!(dummy, a, b, c, d, e, f, g, h, i, j, k, l,);
--- /dev/null
+use std::collections::HashMap;
+use std::collections::hash_map::Entry;
+use std::hash::Hash;
+use std::fmt;
+use std::iter::FusedIterator;
+
+/// An iterator adapter to filter out duplicate elements.
+///
+/// See [`.unique_by()`](crate::Itertools::unique) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct UniqueBy<I: Iterator, V, F> {
+ iter: I,
+ // Use a Hashmap for the Entry API in order to prevent hashing twice.
+ // This can maybe be replaced with a HashSet once `get_or_insert_with`
+ // or a proper Entry API for Hashset is stable and meets this msrv
+ used: HashMap<V, ()>,
+ f: F,
+}
+
+impl<I, V, F> fmt::Debug for UniqueBy<I, V, F>
+ where I: Iterator + fmt::Debug,
+ V: fmt::Debug + Hash + Eq,
+{
+ debug_fmt_fields!(UniqueBy, iter, used);
+}
+
+/// Create a new `UniqueBy` iterator.
+pub fn unique_by<I, V, F>(iter: I, f: F) -> UniqueBy<I, V, F>
+ where V: Eq + Hash,
+ F: FnMut(&I::Item) -> V,
+ I: Iterator,
+{
+ UniqueBy {
+ iter,
+ used: HashMap::new(),
+ f,
+ }
+}
+
+// count the number of new unique keys in iterable (`used` is the set already seen)
+fn count_new_keys<I, K>(mut used: HashMap<K, ()>, iterable: I) -> usize
+ where I: IntoIterator<Item=K>,
+ K: Hash + Eq,
+{
+ let iter = iterable.into_iter();
+ let current_used = used.len();
+ used.extend(iter.map(|key| (key, ())));
+ used.len() - current_used
+}
+
+impl<I, V, F> Iterator for UniqueBy<I, V, F>
+ where I: Iterator,
+ V: Eq + Hash,
+ F: FnMut(&I::Item) -> V
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.next() {
+ let key = (self.f)(&v);
+ if self.used.insert(key, ()).is_none() {
+ return Some(v);
+ }
+ }
+ None
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (low, hi) = self.iter.size_hint();
+ ((low > 0 && self.used.is_empty()) as usize, hi)
+ }
+
+ fn count(self) -> usize {
+ let mut key_f = self.f;
+ count_new_keys(self.used, self.iter.map(move |elt| key_f(&elt)))
+ }
+}
+
+impl<I, V, F> DoubleEndedIterator for UniqueBy<I, V, F>
+ where I: DoubleEndedIterator,
+ V: Eq + Hash,
+ F: FnMut(&I::Item) -> V
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.next_back() {
+ let key = (self.f)(&v);
+ if self.used.insert(key, ()).is_none() {
+ return Some(v);
+ }
+ }
+ None
+ }
+}
+
+impl<I, V, F> FusedIterator for UniqueBy<I, V, F>
+ where I: FusedIterator,
+ V: Eq + Hash,
+ F: FnMut(&I::Item) -> V
+{}
+
+impl<I> Iterator for Unique<I>
+ where I: Iterator,
+ I::Item: Eq + Hash + Clone
+{
+ type Item = I::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.iter.next() {
+ if let Entry::Vacant(entry) = self.iter.used.entry(v) {
+ let elt = entry.key().clone();
+ entry.insert(());
+ return Some(elt);
+ }
+ }
+ None
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ let (low, hi) = self.iter.iter.size_hint();
+ ((low > 0 && self.iter.used.is_empty()) as usize, hi)
+ }
+
+ fn count(self) -> usize {
+ count_new_keys(self.iter.used, self.iter.iter)
+ }
+}
+
+impl<I> DoubleEndedIterator for Unique<I>
+ where I: DoubleEndedIterator,
+ I::Item: Eq + Hash + Clone
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ while let Some(v) = self.iter.iter.next_back() {
+ if let Entry::Vacant(entry) = self.iter.used.entry(v) {
+ let elt = entry.key().clone();
+ entry.insert(());
+ return Some(elt);
+ }
+ }
+ None
+ }
+}
+
+impl<I> FusedIterator for Unique<I>
+ where I: FusedIterator,
+ I::Item: Eq + Hash + Clone
+{}
+
+/// An iterator adapter to filter out duplicate elements.
+///
+/// See [`.unique()`](crate::Itertools::unique) for more information.
+#[derive(Clone)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Unique<I: Iterator> {
+ iter: UniqueBy<I, I::Item, ()>,
+}
+
+impl<I> fmt::Debug for Unique<I>
+ where I: Iterator + fmt::Debug,
+ I::Item: Hash + Eq + fmt::Debug,
+{
+ debug_fmt_fields!(Unique, iter);
+}
+
+pub fn unique<I>(iter: I) -> Unique<I>
+ where I: Iterator,
+ I::Item: Eq + Hash,
+{
+ Unique {
+ iter: UniqueBy {
+ iter,
+ used: HashMap::new(),
+ f: (),
+ }
+ }
+}
--- /dev/null
+/// Converts an iterator of tuples into a tuple of containers.
+///
+/// `unzip()` consumes an entire iterator of n-ary tuples, producing `n` collections, one for each
+/// column.
+///
+/// This function is, in some sense, the opposite of [`multizip`].
+///
+/// ```
+/// use itertools::multiunzip;
+///
+/// let inputs = vec![(1, 2, 3), (4, 5, 6), (7, 8, 9)];
+///
+/// let (a, b, c): (Vec<_>, Vec<_>, Vec<_>) = multiunzip(inputs);
+///
+/// assert_eq!(a, vec![1, 4, 7]);
+/// assert_eq!(b, vec![2, 5, 8]);
+/// assert_eq!(c, vec![3, 6, 9]);
+/// ```
+///
+/// [`multizip`]: crate::multizip
+pub fn multiunzip<FromI, I>(i: I) -> FromI
+where
+ I: IntoIterator,
+ I::IntoIter: MultiUnzip<FromI>,
+{
+ i.into_iter().multiunzip()
+}
+
+/// An iterator that can be unzipped into multiple collections.
+///
+/// See [`.multiunzip()`](crate::Itertools::multiunzip) for more information.
+pub trait MultiUnzip<FromI>: Iterator {
+ /// Unzip this iterator into multiple collections.
+ fn multiunzip(self) -> FromI;
+}
+
+macro_rules! impl_unzip_iter {
+ ($($T:ident => $FromT:ident),*) => (
+ #[allow(non_snake_case)]
+ impl<IT: Iterator<Item = ($($T,)*)>, $($T, $FromT: Default + Extend<$T>),* > MultiUnzip<($($FromT,)*)> for IT {
+ fn multiunzip(self) -> ($($FromT,)*) {
+ // This implementation mirrors the logic of Iterator::unzip resp. Extend for (A, B) as close as possible.
+ // Unfortunately a lot of the used api there is still unstable (https://github.com/rust-lang/rust/issues/72631).
+ //
+ // Iterator::unzip: https://doc.rust-lang.org/src/core/iter/traits/iterator.rs.html#2825-2865
+ // Extend for (A, B): https://doc.rust-lang.org/src/core/iter/traits/collect.rs.html#370-411
+
+ let mut res = ($($FromT::default(),)*);
+ let ($($FromT,)*) = &mut res;
+
+ // Still unstable #72631
+ // let (lower_bound, _) = self.size_hint();
+ // if lower_bound > 0 {
+ // $($FromT.extend_reserve(lower_bound);)*
+ // }
+
+ self.fold((), |(), ($($T,)*)| {
+ // Still unstable #72631
+ // $( $FromT.extend_one($T); )*
+ $( $FromT.extend(std::iter::once($T)); )*
+ });
+ res
+ }
+ }
+ );
+}
+
+impl_unzip_iter!();
+impl_unzip_iter!(A => FromA);
+impl_unzip_iter!(A => FromA, B => FromB);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ, K => FromK);
+impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ, K => FromK, L => FromL);
--- /dev/null
+use std::iter::{Fuse,Peekable, FusedIterator};
+
+/// An iterator adaptor that wraps each element in an [`Position`].
+///
+/// Iterator element type is `Position<I::Item>`.
+///
+/// See [`.with_position()`](crate::Itertools::with_position) for more information.
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct WithPosition<I>
+ where I: Iterator,
+{
+ handled_first: bool,
+ peekable: Peekable<Fuse<I>>,
+}
+
+impl<I> Clone for WithPosition<I>
+ where I: Clone + Iterator,
+ I::Item: Clone,
+{
+ clone_fields!(handled_first, peekable);
+}
+
+/// Create a new `WithPosition` iterator.
+pub fn with_position<I>(iter: I) -> WithPosition<I>
+ where I: Iterator,
+{
+ WithPosition {
+ handled_first: false,
+ peekable: iter.fuse().peekable(),
+ }
+}
+
+/// A value yielded by `WithPosition`.
+/// Indicates the position of this element in the iterator results.
+///
+/// See [`.with_position()`](crate::Itertools::with_position) for more information.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum Position<T> {
+ /// This is the first element.
+ First(T),
+ /// This is neither the first nor the last element.
+ Middle(T),
+ /// This is the last element.
+ Last(T),
+ /// This is the only element.
+ Only(T),
+}
+
+impl<T> Position<T> {
+ /// Return the inner value.
+ pub fn into_inner(self) -> T {
+ match self {
+ Position::First(x) |
+ Position::Middle(x) |
+ Position::Last(x) |
+ Position::Only(x) => x,
+ }
+ }
+}
+
+impl<I: Iterator> Iterator for WithPosition<I> {
+ type Item = Position<I::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match self.peekable.next() {
+ Some(item) => {
+ if !self.handled_first {
+ // Haven't seen the first item yet, and there is one to give.
+ self.handled_first = true;
+ // Peek to see if this is also the last item,
+ // in which case tag it as `Only`.
+ match self.peekable.peek() {
+ Some(_) => Some(Position::First(item)),
+ None => Some(Position::Only(item)),
+ }
+ } else {
+ // Have seen the first item, and there's something left.
+ // Peek to see if this is the last item.
+ match self.peekable.peek() {
+ Some(_) => Some(Position::Middle(item)),
+ None => Some(Position::Last(item)),
+ }
+ }
+ }
+ // Iterator is finished.
+ None => None,
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.peekable.size_hint()
+ }
+}
+
+impl<I> ExactSizeIterator for WithPosition<I>
+ where I: ExactSizeIterator,
+{ }
+
+impl<I: Iterator> FusedIterator for WithPosition<I>
+{}
--- /dev/null
+use super::size_hint;
+
+/// An iterator which iterates two other iterators simultaneously
+///
+/// See [`.zip_eq()`](crate::Itertools::zip_eq) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct ZipEq<I, J> {
+ a: I,
+ b: J,
+}
+
+/// Iterate `i` and `j` in lock step.
+///
+/// **Panics** if the iterators are not of the same length.
+///
+/// [`IntoIterator`] enabled version of [`Itertools::zip_eq`](crate::Itertools::zip_eq).
+///
+/// ```
+/// use itertools::zip_eq;
+///
+/// let data = [1, 2, 3, 4, 5];
+/// for (a, b) in zip_eq(&data[..data.len() - 1], &data[1..]) {
+/// /* loop body */
+/// }
+/// ```
+pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter>
+ where I: IntoIterator,
+ J: IntoIterator
+{
+ ZipEq {
+ a: i.into_iter(),
+ b: j.into_iter(),
+ }
+}
+
+impl<I, J> Iterator for ZipEq<I, J>
+ where I: Iterator,
+ J: Iterator
+{
+ type Item = (I::Item, J::Item);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ match (self.a.next(), self.b.next()) {
+ (None, None) => None,
+ (Some(a), Some(b)) => Some((a, b)),
+ (None, Some(_)) | (Some(_), None) =>
+ panic!("itertools: .zip_eq() reached end of one iterator before the other")
+ }
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::min(self.a.size_hint(), self.b.size_hint())
+ }
+}
+
+impl<I, J> ExactSizeIterator for ZipEq<I, J>
+ where I: ExactSizeIterator,
+ J: ExactSizeIterator
+{}
--- /dev/null
+use std::cmp::Ordering::{Equal, Greater, Less};
+use super::size_hint;
+use std::iter::{Fuse, FusedIterator};
+
+use crate::either_or_both::EitherOrBoth;
+
+// ZipLongest originally written by SimonSapin,
+// and dedicated to itertools https://github.com/rust-lang/rust/pull/19283
+
+/// An iterator which iterates two other iterators simultaneously
+///
+/// This iterator is *fused*.
+///
+/// See [`.zip_longest()`](crate::Itertools::zip_longest) for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct ZipLongest<T, U> {
+ a: Fuse<T>,
+ b: Fuse<U>,
+}
+
+/// Create a new `ZipLongest` iterator.
+pub fn zip_longest<T, U>(a: T, b: U) -> ZipLongest<T, U>
+ where T: Iterator,
+ U: Iterator
+{
+ ZipLongest {
+ a: a.fuse(),
+ b: b.fuse(),
+ }
+}
+
+impl<T, U> Iterator for ZipLongest<T, U>
+ where T: Iterator,
+ U: Iterator
+{
+ type Item = EitherOrBoth<T::Item, U::Item>;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ match (self.a.next(), self.b.next()) {
+ (None, None) => None,
+ (Some(a), None) => Some(EitherOrBoth::Left(a)),
+ (None, Some(b)) => Some(EitherOrBoth::Right(b)),
+ (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)),
+ }
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ size_hint::max(self.a.size_hint(), self.b.size_hint())
+ }
+}
+
+impl<T, U> DoubleEndedIterator for ZipLongest<T, U>
+ where T: DoubleEndedIterator + ExactSizeIterator,
+ U: DoubleEndedIterator + ExactSizeIterator
+{
+ #[inline]
+ fn next_back(&mut self) -> Option<Self::Item> {
+ match self.a.len().cmp(&self.b.len()) {
+ Equal => match (self.a.next_back(), self.b.next_back()) {
+ (None, None) => None,
+ (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)),
+ // These can only happen if .len() is inconsistent with .next_back()
+ (Some(a), None) => Some(EitherOrBoth::Left(a)),
+ (None, Some(b)) => Some(EitherOrBoth::Right(b)),
+ },
+ Greater => self.a.next_back().map(EitherOrBoth::Left),
+ Less => self.b.next_back().map(EitherOrBoth::Right),
+ }
+ }
+}
+
+impl<T, U> ExactSizeIterator for ZipLongest<T, U>
+ where T: ExactSizeIterator,
+ U: ExactSizeIterator
+{}
+
+impl<T, U> FusedIterator for ZipLongest<T, U>
+ where T: Iterator,
+ U: Iterator
+{}
--- /dev/null
+use super::size_hint;
+
+/// See [`multizip`] for more information.
+#[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+pub struct Zip<T> {
+ t: T,
+}
+
+/// An iterator that generalizes *.zip()* and allows running multiple iterators in lockstep.
+///
+/// The iterator `Zip<(I, J, ..., M)>` is formed from a tuple of iterators (or values that
+/// implement [`IntoIterator`]) and yields elements
+/// until any of the subiterators yields `None`.
+///
+/// The iterator element type is a tuple like like `(A, B, ..., E)` where `A` to `E` are the
+/// element types of the subiterator.
+///
+/// **Note:** The result of this macro is a value of a named type (`Zip<(I, J,
+/// ..)>` of each component iterator `I, J, ...`) if each component iterator is
+/// nameable.
+///
+/// Prefer [`izip!()`] over `multizip` for the performance benefits of using the
+/// standard library `.zip()`. Prefer `multizip` if a nameable type is needed.
+///
+/// ```
+/// use itertools::multizip;
+///
+/// // iterate over three sequences side-by-side
+/// let mut results = [0, 0, 0, 0];
+/// let inputs = [3, 7, 9, 6];
+///
+/// for (r, index, input) in multizip((&mut results, 0..10, &inputs)) {
+/// *r = index * 10 + input;
+/// }
+///
+/// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]);
+/// ```
+/// [`izip!()`]: crate::izip
+pub fn multizip<T, U>(t: U) -> Zip<T>
+ where Zip<T>: From<U>,
+ Zip<T>: Iterator,
+{
+ Zip::from(t)
+}
+
+macro_rules! impl_zip_iter {
+ ($($B:ident),*) => (
+ #[allow(non_snake_case)]
+ impl<$($B: IntoIterator),*> From<($($B,)*)> for Zip<($($B::IntoIter,)*)> {
+ fn from(t: ($($B,)*)) -> Self {
+ let ($($B,)*) = t;
+ Zip { t: ($($B.into_iter(),)*) }
+ }
+ }
+
+ #[allow(non_snake_case)]
+ #[allow(unused_assignments)]
+ impl<$($B),*> Iterator for Zip<($($B,)*)>
+ where
+ $(
+ $B: Iterator,
+ )*
+ {
+ type Item = ($($B::Item,)*);
+
+ fn next(&mut self) -> Option<Self::Item>
+ {
+ let ($(ref mut $B,)*) = self.t;
+
+ // NOTE: Just like iter::Zip, we check the iterators
+ // for None in order. We may finish unevenly (some
+ // iterators gave n + 1 elements, some only n).
+ $(
+ let $B = match $B.next() {
+ None => return None,
+ Some(elt) => elt
+ };
+ )*
+ Some(($($B,)*))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>)
+ {
+ let sh = (::std::usize::MAX, None);
+ let ($(ref $B,)*) = self.t;
+ $(
+ let sh = size_hint::min($B.size_hint(), sh);
+ )*
+ sh
+ }
+ }
+
+ #[allow(non_snake_case)]
+ impl<$($B),*> ExactSizeIterator for Zip<($($B,)*)> where
+ $(
+ $B: ExactSizeIterator,
+ )*
+ { }
+
+ #[allow(non_snake_case)]
+ impl<$($B),*> DoubleEndedIterator for Zip<($($B,)*)> where
+ $(
+ $B: DoubleEndedIterator + ExactSizeIterator,
+ )*
+ {
+ #[inline]
+ fn next_back(&mut self) -> Option<Self::Item> {
+ let ($(ref mut $B,)*) = self.t;
+ let size = *[$( $B.len(), )*].iter().min().unwrap();
+
+ $(
+ if $B.len() != size {
+ for _ in 0..$B.len() - size { $B.next_back(); }
+ }
+ )*
+
+ match ($($B.next_back(),)*) {
+ ($(Some($B),)*) => Some(($($B,)*)),
+ _ => None,
+ }
+ }
+ }
+ );
+}
+
+impl_zip_iter!(A);
+impl_zip_iter!(A, B);
+impl_zip_iter!(A, B, C);
+impl_zip_iter!(A, B, C, D);
+impl_zip_iter!(A, B, C, D, E);
+impl_zip_iter!(A, B, C, D, E, F);
+impl_zip_iter!(A, B, C, D, E, F, G);
+impl_zip_iter!(A, B, C, D, E, F, G, H);
+impl_zip_iter!(A, B, C, D, E, F, G, H, I);
+impl_zip_iter!(A, B, C, D, E, F, G, H, I, J);
+impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K);
+impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K, L);
--- /dev/null
+use itertools::Itertools;
+
+struct PanickingCounter {
+ curr: usize,
+ max: usize,
+}
+
+impl Iterator for PanickingCounter {
+ type Item = ();
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.curr += 1;
+
+ assert_ne!(
+ self.curr, self.max,
+ "Input iterator reached maximum of {} suggesting collection by adaptor",
+ self.max
+ );
+
+ Some(())
+ }
+}
+
+fn no_collect_test<A, T>(to_adaptor: T)
+ where A: Iterator, T: Fn(PanickingCounter) -> A
+{
+ let counter = PanickingCounter { curr: 0, max: 10_000 };
+ let adaptor = to_adaptor(counter);
+
+ for _ in adaptor.take(5) {}
+}
+
+#[test]
+fn permutations_no_collect() {
+ no_collect_test(|iter| iter.permutations(5))
+}
+
+#[test]
+fn combinations_no_collect() {
+ no_collect_test(|iter| iter.combinations(5))
+}
+
+#[test]
+fn combinations_with_replacement_no_collect() {
+ no_collect_test(|iter| iter.combinations_with_replacement(5))
+}
\ No newline at end of file
--- /dev/null
+use itertools::{assert_equal, Itertools};
+use std::{ops::Range, vec::IntoIter};
+
+fn mix_data() -> IntoIter<Result<Range<i32>, bool>> {
+ vec![Ok(0..2), Err(false), Ok(2..4), Err(true), Ok(4..6)].into_iter()
+}
+
+fn ok_data() -> IntoIter<Result<Range<i32>, bool>> {
+ vec![Ok(0..2), Ok(2..4), Ok(4..6)].into_iter()
+}
+
+#[test]
+fn flatten_ok_mixed_expected_forward() {
+ assert_equal(
+ mix_data().flatten_ok(),
+ vec![
+ Ok(0),
+ Ok(1),
+ Err(false),
+ Ok(2),
+ Ok(3),
+ Err(true),
+ Ok(4),
+ Ok(5),
+ ],
+ );
+}
+
+#[test]
+fn flatten_ok_mixed_expected_reverse() {
+ assert_equal(
+ mix_data().flatten_ok().rev(),
+ vec![
+ Ok(5),
+ Ok(4),
+ Err(true),
+ Ok(3),
+ Ok(2),
+ Err(false),
+ Ok(1),
+ Ok(0),
+ ],
+ );
+}
+
+#[test]
+fn flatten_ok_collect_mixed_forward() {
+ assert_eq!(
+ mix_data().flatten_ok().collect::<Result<Vec<_>, _>>(),
+ Err(false)
+ );
+}
+
+#[test]
+fn flatten_ok_collect_mixed_reverse() {
+ assert_eq!(
+ mix_data().flatten_ok().rev().collect::<Result<Vec<_>, _>>(),
+ Err(true)
+ );
+}
+
+#[test]
+fn flatten_ok_collect_ok_forward() {
+ assert_eq!(
+ ok_data().flatten_ok().collect::<Result<Vec<_>, _>>(),
+ Ok((0..6).collect())
+ );
+}
+
+#[test]
+fn flatten_ok_collect_ok_reverse() {
+ assert_eq!(
+ ok_data().flatten_ok().rev().collect::<Result<Vec<_>, _>>(),
+ Ok((0..6).rev().collect())
+ );
+}
--- /dev/null
+#[test]
+fn iproduct_hygiene() {
+ let _ = itertools::iproduct!(0..6);
+ let _ = itertools::iproduct!(0..6, 0..9);
+ let _ = itertools::iproduct!(0..6, 0..9, 0..12);
+}
+
+#[test]
+fn izip_hygiene() {
+ let _ = itertools::izip!(0..6);
+ let _ = itertools::izip!(0..6, 0..9);
+ let _ = itertools::izip!(0..6, 0..9, 0..12);
+}
--- /dev/null
+use itertools::EitherOrBoth;
+use itertools::free::merge_join_by;
+
+#[test]
+fn empty() {
+ let left: Vec<u32> = vec![];
+ let right: Vec<u32> = vec![];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn left_only() {
+ let left: Vec<u32> = vec![1,2,3];
+ let right: Vec<u32> = vec![];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Left(1),
+ EitherOrBoth::Left(2),
+ EitherOrBoth::Left(3)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn right_only() {
+ let left: Vec<u32> = vec![];
+ let right: Vec<u32> = vec![1,2,3];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Right(1),
+ EitherOrBoth::Right(2),
+ EitherOrBoth::Right(3)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn first_left_then_right() {
+ let left: Vec<u32> = vec![1,2,3];
+ let right: Vec<u32> = vec![4,5,6];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Left(1),
+ EitherOrBoth::Left(2),
+ EitherOrBoth::Left(3),
+ EitherOrBoth::Right(4),
+ EitherOrBoth::Right(5),
+ EitherOrBoth::Right(6)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn first_right_then_left() {
+ let left: Vec<u32> = vec![4,5,6];
+ let right: Vec<u32> = vec![1,2,3];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Right(1),
+ EitherOrBoth::Right(2),
+ EitherOrBoth::Right(3),
+ EitherOrBoth::Left(4),
+ EitherOrBoth::Left(5),
+ EitherOrBoth::Left(6)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn interspersed_left_and_right() {
+ let left: Vec<u32> = vec![1,3,5];
+ let right: Vec<u32> = vec![2,4,6];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Left(1),
+ EitherOrBoth::Right(2),
+ EitherOrBoth::Left(3),
+ EitherOrBoth::Right(4),
+ EitherOrBoth::Left(5),
+ EitherOrBoth::Right(6)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
+
+#[test]
+fn overlapping_left_and_right() {
+ let left: Vec<u32> = vec![1,3,4,6];
+ let right: Vec<u32> = vec![2,3,4,5];
+ let expected_result: Vec<EitherOrBoth<u32, u32>> = vec![
+ EitherOrBoth::Left(1),
+ EitherOrBoth::Right(2),
+ EitherOrBoth::Both(3, 3),
+ EitherOrBoth::Both(4, 4),
+ EitherOrBoth::Right(5),
+ EitherOrBoth::Left(6)
+ ];
+ let actual_result = merge_join_by(left, right, |l, r| l.cmp(r))
+ .collect::<Vec<_>>();
+ assert_eq!(expected_result, actual_result);
+}
--- /dev/null
+use itertools::Itertools;
+use itertools::{put_back, put_back_n};
+
+#[test]
+fn peeking_take_while_peekable() {
+ let mut r = (0..10).peekable();
+ r.peeking_take_while(|x| *x <= 3).count();
+ assert_eq!(r.next(), Some(4));
+}
+
+#[test]
+fn peeking_take_while_put_back() {
+ let mut r = put_back(0..10);
+ r.peeking_take_while(|x| *x <= 3).count();
+ assert_eq!(r.next(), Some(4));
+ r.peeking_take_while(|_| true).count();
+ assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_put_back_n() {
+ let mut r = put_back_n(6..10);
+ for elt in (0..6).rev() {
+ r.put_back(elt);
+ }
+ r.peeking_take_while(|x| *x <= 3).count();
+ assert_eq!(r.next(), Some(4));
+ r.peeking_take_while(|_| true).count();
+ assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_slice_iter() {
+ let v = [1, 2, 3, 4, 5, 6];
+ let mut r = v.iter();
+ r.peeking_take_while(|x| **x <= 3).count();
+ assert_eq!(r.next(), Some(&4));
+ r.peeking_take_while(|_| true).count();
+ assert_eq!(r.next(), None);
+}
+
+#[test]
+fn peeking_take_while_slice_iter_rev() {
+ let v = [1, 2, 3, 4, 5, 6];
+ let mut r = v.iter().rev();
+ r.peeking_take_while(|x| **x >= 3).count();
+ assert_eq!(r.next(), Some(&2));
+ r.peeking_take_while(|_| true).count();
+ assert_eq!(r.next(), None);
+}
--- /dev/null
+//! The purpose of these tests is to cover corner cases of iterators
+//! and adaptors.
+//!
+//! In particular we test the tedious size_hint and exact size correctness.
+
+use quickcheck as qc;
+use std::default::Default;
+use std::num::Wrapping;
+use std::ops::Range;
+use std::cmp::{max, min, Ordering};
+use std::collections::{HashMap, HashSet};
+use itertools::Itertools;
+use itertools::{
+ multizip,
+ EitherOrBoth,
+ iproduct,
+ izip,
+};
+use itertools::free::{
+ cloned,
+ enumerate,
+ multipeek,
+ peek_nth,
+ put_back,
+ put_back_n,
+ rciter,
+ zip,
+ zip_eq,
+};
+
+use rand::Rng;
+use rand::seq::SliceRandom;
+use quickcheck::TestResult;
+
+/// Trait for size hint modifier types
+trait HintKind: Copy + Send + qc::Arbitrary {
+ fn loosen_bounds(&self, org_hint: (usize, Option<usize>)) -> (usize, Option<usize>);
+}
+
+/// Exact size hint variant that leaves hints unchanged
+#[derive(Clone, Copy, Debug)]
+struct Exact {}
+
+impl HintKind for Exact {
+ fn loosen_bounds(&self, org_hint: (usize, Option<usize>)) -> (usize, Option<usize>) {
+ org_hint
+ }
+}
+
+impl qc::Arbitrary for Exact {
+ fn arbitrary<G: qc::Gen>(_: &mut G) -> Self {
+ Exact {}
+ }
+}
+
+/// Inexact size hint variant to simulate imprecise (but valid) size hints
+///
+/// Will always decrease the lower bound and increase the upper bound
+/// of the size hint by set amounts.
+#[derive(Clone, Copy, Debug)]
+struct Inexact {
+ underestimate: usize,
+ overestimate: usize,
+}
+
+impl HintKind for Inexact {
+ fn loosen_bounds(&self, org_hint: (usize, Option<usize>)) -> (usize, Option<usize>) {
+ let (org_lower, org_upper) = org_hint;
+ (org_lower.saturating_sub(self.underestimate),
+ org_upper.and_then(move |x| x.checked_add(self.overestimate)))
+ }
+}
+
+impl qc::Arbitrary for Inexact {
+ fn arbitrary<G: qc::Gen>(g: &mut G) -> Self {
+ let ue_value = usize::arbitrary(g);
+ let oe_value = usize::arbitrary(g);
+ // Compensate for quickcheck using extreme values too rarely
+ let ue_choices = &[0, ue_value, usize::max_value()];
+ let oe_choices = &[0, oe_value, usize::max_value()];
+ Inexact {
+ underestimate: *ue_choices.choose(g).unwrap(),
+ overestimate: *oe_choices.choose(g).unwrap(),
+ }
+ }
+
+ fn shrink(&self) -> Box<dyn Iterator<Item=Self>> {
+ let underestimate_value = self.underestimate;
+ let overestimate_value = self.overestimate;
+ Box::new(
+ underestimate_value.shrink().flat_map(move |ue_value|
+ overestimate_value.shrink().map(move |oe_value|
+ Inexact {
+ underestimate: ue_value,
+ overestimate: oe_value,
+ }
+ )
+ )
+ )
+ }
+}
+
+/// Our base iterator that we can impl Arbitrary for
+///
+/// By default we'll return inexact bounds estimates for size_hint
+/// to make tests harder to pass.
+///
+/// NOTE: Iter is tricky and is not fused, to help catch bugs.
+/// At the end it will return None once, then return Some(0),
+/// then return None again.
+#[derive(Clone, Debug)]
+struct Iter<T, SK: HintKind = Inexact> {
+ iterator: Range<T>,
+ // fuse/done flag
+ fuse_flag: i32,
+ hint_kind: SK,
+}
+
+impl<T, HK> Iter<T, HK> where HK: HintKind
+{
+ fn new(it: Range<T>, hint_kind: HK) -> Self {
+ Iter {
+ iterator: it,
+ fuse_flag: 0,
+ hint_kind,
+ }
+ }
+}
+
+impl<T, HK> Iterator for Iter<T, HK>
+ where Range<T>: Iterator,
+ <Range<T> as Iterator>::Item: Default,
+ HK: HintKind,
+{
+ type Item = <Range<T> as Iterator>::Item;
+
+ fn next(&mut self) -> Option<Self::Item>
+ {
+ let elt = self.iterator.next();
+ if elt.is_none() {
+ self.fuse_flag += 1;
+ // check fuse flag
+ if self.fuse_flag == 2 {
+ return Some(Default::default())
+ }
+ }
+ elt
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>)
+ {
+ let org_hint = self.iterator.size_hint();
+ self.hint_kind.loosen_bounds(org_hint)
+ }
+}
+
+impl<T, HK> DoubleEndedIterator for Iter<T, HK>
+ where Range<T>: DoubleEndedIterator,
+ <Range<T> as Iterator>::Item: Default,
+ HK: HintKind
+{
+ fn next_back(&mut self) -> Option<Self::Item> { self.iterator.next_back() }
+}
+
+impl<T> ExactSizeIterator for Iter<T, Exact> where Range<T>: ExactSizeIterator,
+ <Range<T> as Iterator>::Item: Default,
+{ }
+
+impl<T, HK> qc::Arbitrary for Iter<T, HK>
+ where T: qc::Arbitrary,
+ HK: HintKind,
+{
+ fn arbitrary<G: qc::Gen>(g: &mut G) -> Self
+ {
+ Iter::new(T::arbitrary(g)..T::arbitrary(g), HK::arbitrary(g))
+ }
+
+ fn shrink(&self) -> Box<dyn Iterator<Item=Iter<T, HK>>>
+ {
+ let r = self.iterator.clone();
+ let hint_kind = self.hint_kind;
+ Box::new(
+ r.start.shrink().flat_map(move |a|
+ r.end.shrink().map(move |b|
+ Iter::new(a.clone()..b, hint_kind)
+ )
+ )
+ )
+ }
+}
+
+/// A meta-iterator which yields `Iter<i32>`s whose start/endpoints are
+/// increased or decreased linearly on each iteration.
+#[derive(Clone, Debug)]
+struct ShiftRange<HK = Inexact> {
+ range_start: i32,
+ range_end: i32,
+ start_step: i32,
+ end_step: i32,
+ iter_count: u32,
+ hint_kind: HK,
+}
+
+impl<HK> Iterator for ShiftRange<HK> where HK: HintKind {
+ type Item = Iter<i32, HK>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.iter_count == 0 {
+ return None;
+ }
+
+ let iter = Iter::new(self.range_start..self.range_end, self.hint_kind);
+
+ self.range_start += self.start_step;
+ self.range_end += self.end_step;
+ self.iter_count -= 1;
+
+ Some(iter)
+ }
+}
+
+impl ExactSizeIterator for ShiftRange<Exact> { }
+
+impl<HK> qc::Arbitrary for ShiftRange<HK>
+ where HK: HintKind
+{
+ fn arbitrary<G: qc::Gen>(g: &mut G) -> Self {
+ const MAX_STARTING_RANGE_DIFF: i32 = 32;
+ const MAX_STEP_MODULO: i32 = 8;
+ const MAX_ITER_COUNT: u32 = 3;
+
+ let range_start = qc::Arbitrary::arbitrary(g);
+ let range_end = range_start + g.gen_range(0, MAX_STARTING_RANGE_DIFF + 1);
+ let start_step = g.gen_range(-MAX_STEP_MODULO, MAX_STEP_MODULO + 1);
+ let end_step = g.gen_range(-MAX_STEP_MODULO, MAX_STEP_MODULO + 1);
+ let iter_count = g.gen_range(0, MAX_ITER_COUNT + 1);
+ let hint_kind = qc::Arbitrary::arbitrary(g);
+
+ ShiftRange {
+ range_start,
+ range_end,
+ start_step,
+ end_step,
+ iter_count,
+ hint_kind,
+ }
+ }
+}
+
+fn correct_count<I, F>(get_it: F) -> bool
+where
+ I: Iterator,
+ F: Fn() -> I
+{
+ let mut counts = vec![get_it().count()];
+
+ 'outer: loop {
+ let mut it = get_it();
+
+ for _ in 0..(counts.len() - 1) {
+ #[allow(clippy::manual_assert)]
+ if it.next().is_none() {
+ panic!("Iterator shouldn't be finished, may not be deterministic");
+ }
+ }
+
+ if it.next().is_none() {
+ break 'outer;
+ }
+
+ counts.push(it.count());
+ }
+
+ let total_actual_count = counts.len() - 1;
+
+ for (i, returned_count) in counts.into_iter().enumerate() {
+ let actual_count = total_actual_count - i;
+ if actual_count != returned_count {
+ println!("Total iterations: {} True count: {} returned count: {}", i, actual_count, returned_count);
+
+ return false;
+ }
+ }
+
+ true
+}
+
+fn correct_size_hint<I: Iterator>(mut it: I) -> bool {
+ // record size hint at each iteration
+ let initial_hint = it.size_hint();
+ let mut hints = Vec::with_capacity(initial_hint.0 + 1);
+ hints.push(initial_hint);
+ while let Some(_) = it.next() {
+ hints.push(it.size_hint())
+ }
+
+ let mut true_count = hints.len(); // start off +1 too much
+
+ // check all the size hints
+ for &(low, hi) in &hints {
+ true_count -= 1;
+ if low > true_count ||
+ (hi.is_some() && hi.unwrap() < true_count)
+ {
+ println!("True size: {:?}, size hint: {:?}", true_count, (low, hi));
+ //println!("All hints: {:?}", hints);
+ return false
+ }
+ }
+ true
+}
+
+fn exact_size<I: ExactSizeIterator>(mut it: I) -> bool {
+ // check every iteration
+ let (mut low, mut hi) = it.size_hint();
+ if Some(low) != hi { return false; }
+ while let Some(_) = it.next() {
+ let (xlow, xhi) = it.size_hint();
+ if low != xlow + 1 { return false; }
+ low = xlow;
+ hi = xhi;
+ if Some(low) != hi { return false; }
+ }
+ let (low, hi) = it.size_hint();
+ low == 0 && hi == Some(0)
+}
+
+// Exact size for this case, without ExactSizeIterator
+fn exact_size_for_this<I: Iterator>(mut it: I) -> bool {
+ // check every iteration
+ let (mut low, mut hi) = it.size_hint();
+ if Some(low) != hi { return false; }
+ while let Some(_) = it.next() {
+ let (xlow, xhi) = it.size_hint();
+ if low != xlow + 1 { return false; }
+ low = xlow;
+ hi = xhi;
+ if Some(low) != hi { return false; }
+ }
+ let (low, hi) = it.size_hint();
+ low == 0 && hi == Some(0)
+}
+
+/*
+ * NOTE: Range<i8> is broken!
+ * (all signed ranges are)
+#[quickcheck]
+fn size_range_i8(a: Iter<i8>) -> bool {
+ exact_size(a)
+}
+
+#[quickcheck]
+fn size_range_i16(a: Iter<i16>) -> bool {
+ exact_size(a)
+}
+
+#[quickcheck]
+fn size_range_u8(a: Iter<u8>) -> bool {
+ exact_size(a)
+}
+ */
+
+macro_rules! quickcheck {
+ // accept several property function definitions
+ // The property functions can use pattern matching and `mut` as usual
+ // in the function arguments, but the functions can not be generic.
+ {$($(#$attr:tt)* fn $fn_name:ident($($arg:tt)*) -> $ret:ty { $($code:tt)* })*} => (
+ $(
+ #[test]
+ $(#$attr)*
+ fn $fn_name() {
+ fn prop($($arg)*) -> $ret {
+ $($code)*
+ }
+ ::quickcheck::quickcheck(quickcheck!(@fn prop [] $($arg)*));
+ }
+ )*
+ );
+ // parse argument list (with patterns allowed) into prop as fn(_, _) -> _
+ (@fn $f:ident [$($t:tt)*]) => {
+ $f as fn($($t),*) -> _
+ };
+ (@fn $f:ident [$($p:tt)*] : $($tail:tt)*) => {
+ quickcheck!(@fn $f [$($p)* _] $($tail)*)
+ };
+ (@fn $f:ident [$($p:tt)*] $t:tt $($tail:tt)*) => {
+ quickcheck!(@fn $f [$($p)*] $($tail)*)
+ };
+}
+
+quickcheck! {
+
+ fn size_product(a: Iter<u16>, b: Iter<u16>) -> bool {
+ correct_size_hint(a.cartesian_product(b))
+ }
+ fn size_product3(a: Iter<u16>, b: Iter<u16>, c: Iter<u16>) -> bool {
+ correct_size_hint(iproduct!(a, b, c))
+ }
+
+ fn correct_cartesian_product3(a: Iter<u16>, b: Iter<u16>, c: Iter<u16>,
+ take_manual: usize) -> ()
+ {
+ // test correctness of iproduct through regular iteration (take)
+ // and through fold.
+ let ac = a.clone();
+ let br = &b.clone();
+ let cr = &c.clone();
+ let answer: Vec<_> = ac.flat_map(move |ea| br.clone().flat_map(move |eb| cr.clone().map(move |ec| (ea, eb, ec)))).collect();
+ let mut product_iter = iproduct!(a, b, c);
+ let mut actual = Vec::new();
+
+ actual.extend((&mut product_iter).take(take_manual));
+ if actual.len() == take_manual {
+ product_iter.fold((), |(), elt| actual.push(elt));
+ }
+ assert_eq!(answer, actual);
+ }
+
+ fn size_multi_product(a: ShiftRange) -> bool {
+ correct_size_hint(a.multi_cartesian_product())
+ }
+ fn correct_multi_product3(a: ShiftRange, take_manual: usize) -> () {
+ // Fix no. of iterators at 3
+ let a = ShiftRange { iter_count: 3, ..a };
+
+ // test correctness of MultiProduct through regular iteration (take)
+ // and through fold.
+ let mut iters = a.clone();
+ let i0 = iters.next().unwrap();
+ let i1r = &iters.next().unwrap();
+ let i2r = &iters.next().unwrap();
+ let answer: Vec<_> = i0.flat_map(move |ei0| i1r.clone().flat_map(move |ei1| i2r.clone().map(move |ei2| vec![ei0, ei1, ei2]))).collect();
+ let mut multi_product = a.clone().multi_cartesian_product();
+ let mut actual = Vec::new();
+
+ actual.extend((&mut multi_product).take(take_manual));
+ if actual.len() == take_manual {
+ multi_product.fold((), |(), elt| actual.push(elt));
+ }
+ assert_eq!(answer, actual);
+
+ assert_eq!(answer.into_iter().last(), a.multi_cartesian_product().last());
+ }
+
+ #[allow(deprecated)]
+ fn size_step(a: Iter<i16, Exact>, s: usize) -> bool {
+ let mut s = s;
+ if s == 0 {
+ s += 1; // never zero
+ }
+ let filt = a.clone().dedup();
+ correct_size_hint(filt.step(s)) &&
+ exact_size(a.step(s))
+ }
+
+ #[allow(deprecated)]
+ fn equal_step(a: Iter<i16>, s: usize) -> bool {
+ let mut s = s;
+ if s == 0 {
+ s += 1; // never zero
+ }
+ let mut i = 0;
+ itertools::equal(a.clone().step(s), a.filter(|_| {
+ let keep = i % s == 0;
+ i += 1;
+ keep
+ }))
+ }
+
+ #[allow(deprecated)]
+ fn equal_step_vec(a: Vec<i16>, s: usize) -> bool {
+ let mut s = s;
+ if s == 0 {
+ s += 1; // never zero
+ }
+ let mut i = 0;
+ itertools::equal(a.iter().step(s), a.iter().filter(|_| {
+ let keep = i % s == 0;
+ i += 1;
+ keep
+ }))
+ }
+
+ fn size_multipeek(a: Iter<u16, Exact>, s: u8) -> bool {
+ let mut it = multipeek(a);
+ // peek a few times
+ for _ in 0..s {
+ it.peek();
+ }
+ exact_size(it)
+ }
+
+ fn size_peek_nth(a: Iter<u16, Exact>, s: u8) -> bool {
+ let mut it = peek_nth(a);
+ // peek a few times
+ for n in 0..s {
+ it.peek_nth(n as usize);
+ }
+ exact_size(it)
+ }
+
+ fn equal_merge(mut a: Vec<i16>, mut b: Vec<i16>) -> bool {
+ a.sort();
+ b.sort();
+ let mut merged = a.clone();
+ merged.extend(b.iter().cloned());
+ merged.sort();
+ itertools::equal(&merged, a.iter().merge(&b))
+ }
+ fn size_merge(a: Iter<u16>, b: Iter<u16>) -> bool {
+ correct_size_hint(a.merge(b))
+ }
+ fn size_zip(a: Iter<i16, Exact>, b: Iter<i16, Exact>, c: Iter<i16, Exact>) -> bool {
+ let filt = a.clone().dedup();
+ correct_size_hint(multizip((filt, b.clone(), c.clone()))) &&
+ exact_size(multizip((a, b, c)))
+ }
+ fn size_zip_rc(a: Iter<i16>, b: Iter<i16>) -> bool {
+ let rc = rciter(a);
+ correct_size_hint(multizip((&rc, &rc, b)))
+ }
+
+ fn size_zip_macro(a: Iter<i16, Exact>, b: Iter<i16, Exact>, c: Iter<i16, Exact>) -> bool {
+ let filt = a.clone().dedup();
+ correct_size_hint(izip!(filt, b.clone(), c.clone())) &&
+ exact_size(izip!(a, b, c))
+ }
+ fn equal_kmerge(mut a: Vec<i16>, mut b: Vec<i16>, mut c: Vec<i16>) -> bool {
+ use itertools::free::kmerge;
+ a.sort();
+ b.sort();
+ c.sort();
+ let mut merged = a.clone();
+ merged.extend(b.iter().cloned());
+ merged.extend(c.iter().cloned());
+ merged.sort();
+ itertools::equal(merged.into_iter(), kmerge(vec![a, b, c]))
+ }
+
+ // Any number of input iterators
+ fn equal_kmerge_2(mut inputs: Vec<Vec<i16>>) -> bool {
+ use itertools::free::kmerge;
+ // sort the inputs
+ for input in &mut inputs {
+ input.sort();
+ }
+ let mut merged = inputs.concat();
+ merged.sort();
+ itertools::equal(merged.into_iter(), kmerge(inputs))
+ }
+
+ // Any number of input iterators
+ fn equal_kmerge_by_ge(mut inputs: Vec<Vec<i16>>) -> bool {
+ // sort the inputs
+ for input in &mut inputs {
+ input.sort();
+ input.reverse();
+ }
+ let mut merged = inputs.concat();
+ merged.sort();
+ merged.reverse();
+ itertools::equal(merged.into_iter(),
+ inputs.into_iter().kmerge_by(|x, y| x >= y))
+ }
+
+ // Any number of input iterators
+ fn equal_kmerge_by_lt(mut inputs: Vec<Vec<i16>>) -> bool {
+ // sort the inputs
+ for input in &mut inputs {
+ input.sort();
+ }
+ let mut merged = inputs.concat();
+ merged.sort();
+ itertools::equal(merged.into_iter(),
+ inputs.into_iter().kmerge_by(|x, y| x < y))
+ }
+
+ // Any number of input iterators
+ fn equal_kmerge_by_le(mut inputs: Vec<Vec<i16>>) -> bool {
+ // sort the inputs
+ for input in &mut inputs {
+ input.sort();
+ }
+ let mut merged = inputs.concat();
+ merged.sort();
+ itertools::equal(merged.into_iter(),
+ inputs.into_iter().kmerge_by(|x, y| x <= y))
+ }
+ fn size_kmerge(a: Iter<i16>, b: Iter<i16>, c: Iter<i16>) -> bool {
+ use itertools::free::kmerge;
+ correct_size_hint(kmerge(vec![a, b, c]))
+ }
+ fn equal_zip_eq(a: Vec<i32>, b: Vec<i32>) -> bool {
+ let len = std::cmp::min(a.len(), b.len());
+ let a = &a[..len];
+ let b = &b[..len];
+ itertools::equal(zip_eq(a, b), zip(a, b))
+ }
+ fn size_zip_longest(a: Iter<i16, Exact>, b: Iter<i16, Exact>) -> bool {
+ let filt = a.clone().dedup();
+ let filt2 = b.clone().dedup();
+ correct_size_hint(filt.zip_longest(b.clone())) &&
+ correct_size_hint(a.clone().zip_longest(filt2)) &&
+ exact_size(a.zip_longest(b))
+ }
+ fn size_2_zip_longest(a: Iter<i16>, b: Iter<i16>) -> bool {
+ let it = a.clone().zip_longest(b.clone());
+ let jt = a.clone().zip_longest(b.clone());
+ itertools::equal(a,
+ it.filter_map(|elt| match elt {
+ EitherOrBoth::Both(x, _) => Some(x),
+ EitherOrBoth::Left(x) => Some(x),
+ _ => None,
+ }
+ ))
+ &&
+ itertools::equal(b,
+ jt.filter_map(|elt| match elt {
+ EitherOrBoth::Both(_, y) => Some(y),
+ EitherOrBoth::Right(y) => Some(y),
+ _ => None,
+ }
+ ))
+ }
+ fn size_interleave(a: Iter<i16>, b: Iter<i16>) -> bool {
+ correct_size_hint(a.interleave(b))
+ }
+ fn exact_interleave(a: Iter<i16, Exact>, b: Iter<i16, Exact>) -> bool {
+ exact_size_for_this(a.interleave(b))
+ }
+ fn size_interleave_shortest(a: Iter<i16>, b: Iter<i16>) -> bool {
+ correct_size_hint(a.interleave_shortest(b))
+ }
+ fn exact_interleave_shortest(a: Vec<()>, b: Vec<()>) -> bool {
+ exact_size_for_this(a.iter().interleave_shortest(&b))
+ }
+ fn size_intersperse(a: Iter<i16>, x: i16) -> bool {
+ correct_size_hint(a.intersperse(x))
+ }
+ fn equal_intersperse(a: Vec<i32>, x: i32) -> bool {
+ let mut inter = false;
+ let mut i = 0;
+ for elt in a.iter().cloned().intersperse(x) {
+ if inter {
+ if elt != x { return false }
+ } else {
+ if elt != a[i] { return false }
+ i += 1;
+ }
+ inter = !inter;
+ }
+ true
+ }
+
+ fn equal_combinations_2(a: Vec<u8>) -> bool {
+ let mut v = Vec::new();
+ for (i, x) in enumerate(&a) {
+ for y in &a[i + 1..] {
+ v.push((x, y));
+ }
+ }
+ itertools::equal(a.iter().tuple_combinations::<(_, _)>(), v)
+ }
+
+ fn collect_tuple_matches_size(a: Iter<i16>) -> bool {
+ let size = a.clone().count();
+ a.collect_tuple::<(_, _, _)>().is_some() == (size == 3)
+ }
+
+ fn correct_permutations(vals: HashSet<i32>, k: usize) -> () {
+ // Test permutations only on iterators of distinct integers, to prevent
+ // false positives.
+
+ const MAX_N: usize = 5;
+
+ let n = min(vals.len(), MAX_N);
+ let vals: HashSet<i32> = vals.into_iter().take(n).collect();
+
+ let perms = vals.iter().permutations(k);
+
+ let mut actual = HashSet::new();
+
+ for perm in perms {
+ assert_eq!(perm.len(), k);
+
+ let all_items_valid = perm.iter().all(|p| vals.contains(p));
+ assert!(all_items_valid, "perm contains value not from input: {:?}", perm);
+
+ // Check that all perm items are distinct
+ let distinct_len = {
+ let perm_set: HashSet<_> = perm.iter().collect();
+ perm_set.len()
+ };
+ assert_eq!(perm.len(), distinct_len);
+
+ // Check that the perm is new
+ assert!(actual.insert(perm.clone()), "perm already encountered: {:?}", perm);
+ }
+ }
+
+ fn permutations_lexic_order(a: usize, b: usize) -> () {
+ let a = a % 6;
+ let b = b % 6;
+
+ let n = max(a, b);
+ let k = min (a, b);
+
+ let expected_first: Vec<usize> = (0..k).collect();
+ let expected_last: Vec<usize> = ((n - k)..n).rev().collect();
+
+ let mut perms = (0..n).permutations(k);
+
+ let mut curr_perm = match perms.next() {
+ Some(p) => p,
+ None => { return; }
+ };
+
+ assert_eq!(expected_first, curr_perm);
+
+ for next_perm in perms {
+ assert!(
+ next_perm > curr_perm,
+ "next perm isn't greater-than current; next_perm={:?} curr_perm={:?} n={}",
+ next_perm, curr_perm, n
+ );
+
+ curr_perm = next_perm;
+ }
+
+ assert_eq!(expected_last, curr_perm);
+
+ }
+
+ fn permutations_count(n: usize, k: usize) -> bool {
+ let n = n % 6;
+
+ correct_count(|| (0..n).permutations(k))
+ }
+
+ fn permutations_size(a: Iter<i32>, k: usize) -> bool {
+ correct_size_hint(a.take(5).permutations(k))
+ }
+
+ fn permutations_k0_yields_once(n: usize) -> () {
+ let k = 0;
+ let expected: Vec<Vec<usize>> = vec![vec![]];
+ let actual = (0..n).permutations(k).collect_vec();
+
+ assert_eq!(expected, actual);
+ }
+}
+
+quickcheck! {
+ fn dedup_via_coalesce(a: Vec<i32>) -> bool {
+ let mut b = a.clone();
+ b.dedup();
+ itertools::equal(
+ &b,
+ a
+ .iter()
+ .coalesce(|x, y| {
+ if x==y {
+ Ok(x)
+ } else {
+ Err((x, y))
+ }
+ })
+ .fold(vec![], |mut v, n| {
+ v.push(n);
+ v
+ })
+ )
+ }
+}
+
+quickcheck! {
+ fn equal_dedup(a: Vec<i32>) -> bool {
+ let mut b = a.clone();
+ b.dedup();
+ itertools::equal(&b, a.iter().dedup())
+ }
+}
+
+quickcheck! {
+ fn equal_dedup_by(a: Vec<(i32, i32)>) -> bool {
+ let mut b = a.clone();
+ b.dedup_by(|x, y| x.0==y.0);
+ itertools::equal(&b, a.iter().dedup_by(|x, y| x.0==y.0))
+ }
+}
+
+quickcheck! {
+ fn size_dedup(a: Vec<i32>) -> bool {
+ correct_size_hint(a.iter().dedup())
+ }
+}
+
+quickcheck! {
+ fn size_dedup_by(a: Vec<(i32, i32)>) -> bool {
+ correct_size_hint(a.iter().dedup_by(|x, y| x.0==y.0))
+ }
+}
+
+quickcheck! {
+ fn exact_repeatn((n, x): (usize, i32)) -> bool {
+ let it = itertools::repeat_n(x, n);
+ exact_size(it)
+ }
+}
+
+quickcheck! {
+ fn size_put_back(a: Vec<u8>, x: Option<u8>) -> bool {
+ let mut it = put_back(a.into_iter());
+ match x {
+ Some(t) => it.put_back(t),
+ None => {}
+ }
+ correct_size_hint(it)
+ }
+}
+
+quickcheck! {
+ fn size_put_backn(a: Vec<u8>, b: Vec<u8>) -> bool {
+ let mut it = put_back_n(a.into_iter());
+ for elt in b {
+ it.put_back(elt)
+ }
+ correct_size_hint(it)
+ }
+}
+
+quickcheck! {
+ fn size_tee(a: Vec<u8>) -> bool {
+ let (mut t1, mut t2) = a.iter().tee();
+ t1.next();
+ t1.next();
+ t2.next();
+ exact_size(t1) && exact_size(t2)
+ }
+}
+
+quickcheck! {
+ fn size_tee_2(a: Vec<u8>) -> bool {
+ let (mut t1, mut t2) = a.iter().dedup().tee();
+ t1.next();
+ t1.next();
+ t2.next();
+ correct_size_hint(t1) && correct_size_hint(t2)
+ }
+}
+
+quickcheck! {
+ fn size_take_while_ref(a: Vec<u8>, stop: u8) -> bool {
+ correct_size_hint(a.iter().take_while_ref(|x| **x != stop))
+ }
+}
+
+quickcheck! {
+ fn equal_partition(a: Vec<i32>) -> bool {
+ let mut a = a;
+ let mut ap = a.clone();
+ let split_index = itertools::partition(&mut ap, |x| *x >= 0);
+ let parted = (0..split_index).all(|i| ap[i] >= 0) &&
+ (split_index..a.len()).all(|i| ap[i] < 0);
+
+ a.sort();
+ ap.sort();
+ parted && (a == ap)
+ }
+}
+
+quickcheck! {
+ fn size_combinations(it: Iter<i16>) -> bool {
+ correct_size_hint(it.tuple_combinations::<(_, _)>())
+ }
+}
+
+quickcheck! {
+ fn equal_combinations(it: Iter<i16>) -> bool {
+ let values = it.clone().collect_vec();
+ let mut cmb = it.tuple_combinations();
+ for i in 0..values.len() {
+ for j in i+1..values.len() {
+ let pair = (values[i], values[j]);
+ if pair != cmb.next().unwrap() {
+ return false;
+ }
+ }
+ }
+ cmb.next() == None
+ }
+}
+
+quickcheck! {
+ fn size_pad_tail(it: Iter<i8>, pad: u8) -> bool {
+ correct_size_hint(it.clone().pad_using(pad as usize, |_| 0)) &&
+ correct_size_hint(it.dropping(1).rev().pad_using(pad as usize, |_| 0))
+ }
+}
+
+quickcheck! {
+ fn size_pad_tail2(it: Iter<i8, Exact>, pad: u8) -> bool {
+ exact_size(it.pad_using(pad as usize, |_| 0))
+ }
+}
+
+quickcheck! {
+ fn size_powerset(it: Iter<u8, Exact>) -> bool {
+ // Powerset cardinality gets large very quickly, limit input to keep test fast.
+ correct_size_hint(it.take(12).powerset())
+ }
+}
+
+quickcheck! {
+ fn size_duplicates(it: Iter<i8>) -> bool {
+ correct_size_hint(it.duplicates())
+ }
+}
+
+quickcheck! {
+ fn size_unique(it: Iter<i8>) -> bool {
+ correct_size_hint(it.unique())
+ }
+
+ fn count_unique(it: Vec<i8>, take_first: u8) -> () {
+ let answer = {
+ let mut v = it.clone();
+ v.sort(); v.dedup();
+ v.len()
+ };
+ let mut iter = cloned(&it).unique();
+ let first_count = (&mut iter).take(take_first as usize).count();
+ let rest_count = iter.count();
+ assert_eq!(answer, first_count + rest_count);
+ }
+}
+
+quickcheck! {
+ fn fuzz_group_by_lazy_1(it: Iter<u8>) -> bool {
+ let jt = it.clone();
+ let groups = it.group_by(|k| *k);
+ itertools::equal(jt, groups.into_iter().flat_map(|(_, x)| x))
+ }
+}
+
+quickcheck! {
+ fn fuzz_group_by_lazy_2(data: Vec<u8>) -> bool {
+ let groups = data.iter().group_by(|k| *k / 10);
+ let res = itertools::equal(data.iter(), groups.into_iter().flat_map(|(_, x)| x));
+ res
+ }
+}
+
+quickcheck! {
+ fn fuzz_group_by_lazy_3(data: Vec<u8>) -> bool {
+ let grouper = data.iter().group_by(|k| *k / 10);
+ let groups = grouper.into_iter().collect_vec();
+ let res = itertools::equal(data.iter(), groups.into_iter().flat_map(|(_, x)| x));
+ res
+ }
+}
+
+quickcheck! {
+ fn fuzz_group_by_lazy_duo(data: Vec<u8>, order: Vec<(bool, bool)>) -> bool {
+ let grouper = data.iter().group_by(|k| *k / 3);
+ let mut groups1 = grouper.into_iter();
+ let mut groups2 = grouper.into_iter();
+ let mut elts = Vec::<&u8>::new();
+ let mut old_groups = Vec::new();
+
+ let tup1 = |(_, b)| b;
+ for &(ord, consume_now) in &order {
+ let iter = &mut [&mut groups1, &mut groups2][ord as usize];
+ match iter.next() {
+ Some((_, gr)) => if consume_now {
+ for og in old_groups.drain(..) {
+ elts.extend(og);
+ }
+ elts.extend(gr);
+ } else {
+ old_groups.push(gr);
+ },
+ None => break,
+ }
+ }
+ for og in old_groups.drain(..) {
+ elts.extend(og);
+ }
+ for gr in groups1.map(&tup1) { elts.extend(gr); }
+ for gr in groups2.map(&tup1) { elts.extend(gr); }
+ itertools::assert_equal(&data, elts);
+ true
+ }
+}
+
+quickcheck! {
+ fn equal_chunks_lazy(a: Vec<u8>, size: u8) -> bool {
+ let mut size = size;
+ if size == 0 {
+ size += 1;
+ }
+ let chunks = a.iter().chunks(size as usize);
+ let it = a.chunks(size as usize);
+ for (a, b) in chunks.into_iter().zip(it) {
+ if !itertools::equal(a, b) {
+ return false;
+ }
+ }
+ true
+ }
+}
+
+quickcheck! {
+ fn equal_tuple_windows_1(a: Vec<u8>) -> bool {
+ let x = a.windows(1).map(|s| (&s[0], ));
+ let y = a.iter().tuple_windows::<(_,)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuple_windows_2(a: Vec<u8>) -> bool {
+ let x = a.windows(2).map(|s| (&s[0], &s[1]));
+ let y = a.iter().tuple_windows::<(_, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuple_windows_3(a: Vec<u8>) -> bool {
+ let x = a.windows(3).map(|s| (&s[0], &s[1], &s[2]));
+ let y = a.iter().tuple_windows::<(_, _, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuple_windows_4(a: Vec<u8>) -> bool {
+ let x = a.windows(4).map(|s| (&s[0], &s[1], &s[2], &s[3]));
+ let y = a.iter().tuple_windows::<(_, _, _, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuples_1(a: Vec<u8>) -> bool {
+ let x = a.chunks(1).map(|s| (&s[0], ));
+ let y = a.iter().tuples::<(_,)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuples_2(a: Vec<u8>) -> bool {
+ let x = a.chunks(2).filter(|s| s.len() == 2).map(|s| (&s[0], &s[1]));
+ let y = a.iter().tuples::<(_, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuples_3(a: Vec<u8>) -> bool {
+ let x = a.chunks(3).filter(|s| s.len() == 3).map(|s| (&s[0], &s[1], &s[2]));
+ let y = a.iter().tuples::<(_, _, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn equal_tuples_4(a: Vec<u8>) -> bool {
+ let x = a.chunks(4).filter(|s| s.len() == 4).map(|s| (&s[0], &s[1], &s[2], &s[3]));
+ let y = a.iter().tuples::<(_, _, _, _)>();
+ itertools::equal(x, y)
+ }
+
+ fn exact_tuple_buffer(a: Vec<u8>) -> bool {
+ let mut iter = a.iter().tuples::<(_, _, _, _)>();
+ (&mut iter).last();
+ let buffer = iter.into_buffer();
+ assert_eq!(buffer.len(), a.len() % 4);
+ exact_size(buffer)
+ }
+}
+
+// with_position
+quickcheck! {
+ fn with_position_exact_size_1(a: Vec<u8>) -> bool {
+ exact_size_for_this(a.iter().with_position())
+ }
+ fn with_position_exact_size_2(a: Iter<u8, Exact>) -> bool {
+ exact_size_for_this(a.with_position())
+ }
+}
+
+quickcheck! {
+ fn correct_group_map_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let count = a.len();
+ let lookup = a.into_iter().map(|i| (i % modulo, i)).into_group_map();
+
+ assert_eq!(lookup.values().flat_map(|vals| vals.iter()).count(), count);
+
+ for (&key, vals) in lookup.iter() {
+ assert!(vals.iter().all(|&val| val % modulo == key));
+ }
+ }
+}
+
+/// A peculiar type: Equality compares both tuple items, but ordering only the
+/// first item. This is so we can check the stability property easily.
+#[derive(Clone, Debug, PartialEq, Eq)]
+struct Val(u32, u32);
+
+impl PartialOrd<Val> for Val {
+ fn partial_cmp(&self, other: &Val) -> Option<Ordering> {
+ self.0.partial_cmp(&other.0)
+ }
+}
+
+impl Ord for Val {
+ fn cmp(&self, other: &Val) -> Ordering {
+ self.0.cmp(&other.0)
+ }
+}
+
+impl qc::Arbitrary for Val {
+ fn arbitrary<G: qc::Gen>(g: &mut G) -> Self {
+ let (x, y) = <(u32, u32)>::arbitrary(g);
+ Val(x, y)
+ }
+ fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
+ Box::new((self.0, self.1).shrink().map(|(x, y)| Val(x, y)))
+ }
+}
+
+quickcheck! {
+ fn minmax(a: Vec<Val>) -> bool {
+ use itertools::MinMaxResult;
+
+
+ let minmax = a.iter().minmax();
+ let expected = match a.len() {
+ 0 => MinMaxResult::NoElements,
+ 1 => MinMaxResult::OneElement(&a[0]),
+ _ => MinMaxResult::MinMax(a.iter().min().unwrap(),
+ a.iter().max().unwrap()),
+ };
+ minmax == expected
+ }
+}
+
+quickcheck! {
+ fn minmax_f64(a: Vec<f64>) -> TestResult {
+ use itertools::MinMaxResult;
+
+ if a.iter().any(|x| x.is_nan()) {
+ return TestResult::discard();
+ }
+
+ let min = cloned(&a).fold1(f64::min);
+ let max = cloned(&a).fold1(f64::max);
+
+ let minmax = cloned(&a).minmax();
+ let expected = match a.len() {
+ 0 => MinMaxResult::NoElements,
+ 1 => MinMaxResult::OneElement(min.unwrap()),
+ _ => MinMaxResult::MinMax(min.unwrap(), max.unwrap()),
+ };
+ TestResult::from_bool(minmax == expected)
+ }
+}
+
+quickcheck! {
+ #[allow(deprecated)]
+ fn tree_fold1_f64(mut a: Vec<f64>) -> TestResult {
+ fn collapse_adjacent<F>(x: Vec<f64>, mut f: F) -> Vec<f64>
+ where F: FnMut(f64, f64) -> f64
+ {
+ let mut out = Vec::new();
+ for i in (0..x.len()).step(2) {
+ if i == x.len()-1 {
+ out.push(x[i])
+ } else {
+ out.push(f(x[i], x[i+1]));
+ }
+ }
+ out
+ }
+
+ if a.iter().any(|x| x.is_nan()) {
+ return TestResult::discard();
+ }
+
+ let actual = a.iter().cloned().tree_fold1(f64::atan2);
+
+ while a.len() > 1 {
+ a = collapse_adjacent(a, f64::atan2);
+ }
+ let expected = a.pop();
+
+ TestResult::from_bool(actual == expected)
+ }
+}
+
+quickcheck! {
+ fn exactly_one_i32(a: Vec<i32>) -> TestResult {
+ let ret = a.iter().cloned().exactly_one();
+ match a.len() {
+ 1 => TestResult::from_bool(ret.unwrap() == a[0]),
+ _ => TestResult::from_bool(ret.unwrap_err().eq(a.iter().cloned())),
+ }
+ }
+}
+
+quickcheck! {
+ fn at_most_one_i32(a: Vec<i32>) -> TestResult {
+ let ret = a.iter().cloned().at_most_one();
+ match a.len() {
+ 0 => TestResult::from_bool(ret.unwrap() == None),
+ 1 => TestResult::from_bool(ret.unwrap() == Some(a[0])),
+ _ => TestResult::from_bool(ret.unwrap_err().eq(a.iter().cloned())),
+ }
+ }
+}
+
+quickcheck! {
+ fn consistent_grouping_map_with_by(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+
+ let lookup_grouping_map = a.iter().copied().map(|i| (i % modulo, i)).into_grouping_map().collect::<Vec<_>>();
+ let lookup_grouping_map_by = a.iter().copied().into_grouping_map_by(|i| i % modulo).collect::<Vec<_>>();
+
+ assert_eq!(lookup_grouping_map, lookup_grouping_map_by);
+ }
+
+ fn correct_grouping_map_by_aggregate_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo < 2 { 2 } else { modulo } as u64; // Avoid `% 0`
+ let lookup = a.iter()
+ .map(|&b| b as u64) // Avoid overflows
+ .into_grouping_map_by(|i| i % modulo)
+ .aggregate(|acc, &key, val| {
+ assert!(val % modulo == key);
+ if val % (modulo - 1) == 0 {
+ None
+ } else {
+ Some(acc.unwrap_or(0) + val)
+ }
+ });
+
+ let group_map_lookup = a.iter()
+ .map(|&b| b as u64)
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .filter_map(|(key, vals)| {
+ vals.into_iter().fold(None, |acc, val| {
+ if val % (modulo - 1) == 0 {
+ None
+ } else {
+ Some(acc.unwrap_or(0) + val)
+ }
+ }).map(|new_val| (key, new_val))
+ })
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for m in 0..modulo {
+ assert_eq!(
+ lookup.get(&m).copied(),
+ a.iter()
+ .map(|&b| b as u64)
+ .filter(|&val| val % modulo == m)
+ .fold(None, |acc, val| {
+ if val % (modulo - 1) == 0 {
+ None
+ } else {
+ Some(acc.unwrap_or(0) + val)
+ }
+ })
+ );
+ }
+ }
+
+ fn correct_grouping_map_by_fold_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo } as u64; // Avoid `% 0`
+ let lookup = a.iter().map(|&b| b as u64) // Avoid overflows
+ .into_grouping_map_by(|i| i % modulo)
+ .fold(0u64, |acc, &key, val| {
+ assert!(val % modulo == key);
+ acc + val
+ });
+
+ let group_map_lookup = a.iter()
+ .map(|&b| b as u64)
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().sum()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &sum) in lookup.iter() {
+ assert_eq!(sum, a.iter().map(|&b| b as u64).filter(|&val| val % modulo == key).sum::<u64>());
+ }
+ }
+
+ fn correct_grouping_map_by_fold_first_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo } as u64; // Avoid `% 0`
+ let lookup = a.iter().map(|&b| b as u64) // Avoid overflows
+ .into_grouping_map_by(|i| i % modulo)
+ .fold_first(|acc, &key, val| {
+ assert!(val % modulo == key);
+ acc + val
+ });
+
+ // TODO: Swap `fold1` with stdlib's `fold_first` when it's stabilized
+ let group_map_lookup = a.iter()
+ .map(|&b| b as u64)
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().fold1(|acc, val| acc + val).unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &sum) in lookup.iter() {
+ assert_eq!(sum, a.iter().map(|&b| b as u64).filter(|&val| val % modulo == key).sum::<u64>());
+ }
+ }
+
+ fn correct_grouping_map_by_collect_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup_grouping_map = a.iter().copied().into_grouping_map_by(|i| i % modulo).collect::<Vec<_>>();
+ let lookup_group_map = a.iter().copied().map(|i| (i % modulo, i)).into_group_map();
+
+ assert_eq!(lookup_grouping_map, lookup_group_map);
+ }
+
+ fn correct_grouping_map_by_max_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).max();
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().max().unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &max) in lookup.iter() {
+ assert_eq!(Some(max), a.iter().copied().filter(|&val| val % modulo == key).max());
+ }
+ }
+
+ fn correct_grouping_map_by_max_by_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).max_by(|_, v1, v2| v1.cmp(v2));
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().max_by(|v1, v2| v1.cmp(v2)).unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &max) in lookup.iter() {
+ assert_eq!(Some(max), a.iter().copied().filter(|&val| val % modulo == key).max_by(|v1, v2| v1.cmp(v2)));
+ }
+ }
+
+ fn correct_grouping_map_by_max_by_key_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).max_by_key(|_, &val| val);
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().max_by_key(|&val| val).unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &max) in lookup.iter() {
+ assert_eq!(Some(max), a.iter().copied().filter(|&val| val % modulo == key).max_by_key(|&val| val));
+ }
+ }
+
+ fn correct_grouping_map_by_min_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).min();
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().min().unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &min) in lookup.iter() {
+ assert_eq!(Some(min), a.iter().copied().filter(|&val| val % modulo == key).min());
+ }
+ }
+
+ fn correct_grouping_map_by_min_by_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).min_by(|_, v1, v2| v1.cmp(v2));
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().min_by(|v1, v2| v1.cmp(v2)).unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &min) in lookup.iter() {
+ assert_eq!(Some(min), a.iter().copied().filter(|&val| val % modulo == key).min_by(|v1, v2| v1.cmp(v2)));
+ }
+ }
+
+ fn correct_grouping_map_by_min_by_key_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).min_by_key(|_, &val| val);
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().min_by_key(|&val| val).unwrap()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &min) in lookup.iter() {
+ assert_eq!(Some(min), a.iter().copied().filter(|&val| val % modulo == key).min_by_key(|&val| val));
+ }
+ }
+
+ fn correct_grouping_map_by_minmax_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).minmax();
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().minmax()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &minmax) in lookup.iter() {
+ assert_eq!(minmax, a.iter().copied().filter(|&val| val % modulo == key).minmax());
+ }
+ }
+
+ fn correct_grouping_map_by_minmax_by_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).minmax_by(|_, v1, v2| v1.cmp(v2));
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().minmax_by(|v1, v2| v1.cmp(v2))))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &minmax) in lookup.iter() {
+ assert_eq!(minmax, a.iter().copied().filter(|&val| val % modulo == key).minmax_by(|v1, v2| v1.cmp(v2)));
+ }
+ }
+
+ fn correct_grouping_map_by_minmax_by_key_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo }; // Avoid `% 0`
+ let lookup = a.iter().copied().into_grouping_map_by(|i| i % modulo).minmax_by_key(|_, &val| val);
+
+ let group_map_lookup = a.iter().copied()
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().minmax_by_key(|&val| val)))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &minmax) in lookup.iter() {
+ assert_eq!(minmax, a.iter().copied().filter(|&val| val % modulo == key).minmax_by_key(|&val| val));
+ }
+ }
+
+ fn correct_grouping_map_by_sum_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = if modulo == 0 { 1 } else { modulo } as u64; // Avoid `% 0`
+ let lookup = a.iter().map(|&b| b as u64) // Avoid overflows
+ .into_grouping_map_by(|i| i % modulo)
+ .sum();
+
+ let group_map_lookup = a.iter().map(|&b| b as u64)
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().sum()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &sum) in lookup.iter() {
+ assert_eq!(sum, a.iter().map(|&b| b as u64).filter(|&val| val % modulo == key).sum::<u64>());
+ }
+ }
+
+ fn correct_grouping_map_by_product_modulo_key(a: Vec<u8>, modulo: u8) -> () {
+ let modulo = Wrapping(if modulo == 0 { 1 } else { modulo } as u64); // Avoid `% 0`
+ let lookup = a.iter().map(|&b| Wrapping(b as u64)) // Avoid overflows
+ .into_grouping_map_by(|i| i % modulo)
+ .product();
+
+ let group_map_lookup = a.iter().map(|&b| Wrapping(b as u64))
+ .map(|i| (i % modulo, i))
+ .into_group_map()
+ .into_iter()
+ .map(|(key, vals)| (key, vals.into_iter().product::<Wrapping<u64>>()))
+ .collect::<HashMap<_,_>>();
+ assert_eq!(lookup, group_map_lookup);
+
+ for (&key, &prod) in lookup.iter() {
+ assert_eq!(
+ prod,
+ a.iter()
+ .map(|&b| Wrapping(b as u64))
+ .filter(|&val| val % modulo == key)
+ .product::<Wrapping<u64>>()
+ );
+ }
+ }
+
+ // This should check that if multiple elements are equally minimum or maximum
+ // then `max`, `min` and `minmax` pick the first minimum and the last maximum.
+ // This is to be consistent with `std::iter::max` and `std::iter::min`.
+ fn correct_grouping_map_by_min_max_minmax_order_modulo_key() -> () {
+ use itertools::MinMaxResult;
+
+ let lookup = (0..=10)
+ .into_grouping_map_by(|_| 0)
+ .max_by(|_, _, _| Ordering::Equal);
+
+ assert_eq!(lookup[&0], 10);
+
+ let lookup = (0..=10)
+ .into_grouping_map_by(|_| 0)
+ .min_by(|_, _, _| Ordering::Equal);
+
+ assert_eq!(lookup[&0], 0);
+
+ let lookup = (0..=10)
+ .into_grouping_map_by(|_| 0)
+ .minmax_by(|_, _, _| Ordering::Equal);
+
+ assert_eq!(lookup[&0], MinMaxResult::MinMax(0, 10));
+ }
+}
+
+quickcheck! {
+ fn counts(nums: Vec<isize>) -> TestResult {
+ let counts = nums.iter().counts();
+ for (&item, &count) in counts.iter() {
+ #[allow(clippy::absurd_extreme_comparisons)]
+ if count <= 0 {
+ return TestResult::failed();
+ }
+ if count != nums.iter().filter(|&x| x == item).count() {
+ return TestResult::failed();
+ }
+ }
+ for item in nums.iter() {
+ if !counts.contains_key(item) {
+ return TestResult::failed();
+ }
+ }
+ TestResult::passed()
+ }
+}
+
+quickcheck! {
+ fn test_double_ended_zip_2(a: Vec<u8>, b: Vec<u8>) -> TestResult {
+ let mut x =
+ multizip((a.clone().into_iter(), b.clone().into_iter()))
+ .collect_vec();
+ x.reverse();
+
+ let y =
+ multizip((a.into_iter(), b.into_iter()))
+ .rfold(Vec::new(), |mut vec, e| { vec.push(e); vec });
+
+ TestResult::from_bool(itertools::equal(x, y))
+ }
+
+ fn test_double_ended_zip_3(a: Vec<u8>, b: Vec<u8>, c: Vec<u8>) -> TestResult {
+ let mut x =
+ multizip((a.clone().into_iter(), b.clone().into_iter(), c.clone().into_iter()))
+ .collect_vec();
+ x.reverse();
+
+ let y =
+ multizip((a.into_iter(), b.into_iter(), c.into_iter()))
+ .rfold(Vec::new(), |mut vec, e| { vec.push(e); vec });
+
+ TestResult::from_bool(itertools::equal(x, y))
+ }
+}
+
+
+fn is_fused<I: Iterator>(mut it: I) -> bool
+{
+ for _ in it.by_ref() {}
+ for _ in 0..10{
+ if it.next().is_some(){
+ return false;
+ }
+ }
+ true
+}
+
+quickcheck! {
+ fn fused_combination(a: Iter<i16>) -> bool
+ {
+ is_fused(a.clone().combinations(1)) &&
+ is_fused(a.combinations(3))
+ }
+
+ fn fused_combination_with_replacement(a: Iter<i16>) -> bool
+ {
+ is_fused(a.clone().combinations_with_replacement(1)) &&
+ is_fused(a.combinations_with_replacement(3))
+ }
+
+ fn fused_tuple_combination(a: Iter<i16>) -> bool
+ {
+ is_fused(a.clone().fuse().tuple_combinations::<(_,)>()) &&
+ is_fused(a.fuse().tuple_combinations::<(_,_,_)>())
+ }
+
+ fn fused_unique(a: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().unique())
+ }
+
+ fn fused_unique_by(a: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().unique_by(|x| x % 100))
+ }
+
+ fn fused_interleave_shortest(a: Iter<i16>, b: Iter<i16>) -> bool
+ {
+ !is_fused(a.clone().interleave_shortest(b.clone())) &&
+ is_fused(a.fuse().interleave_shortest(b.fuse()))
+ }
+
+ fn fused_product(a: Iter<i16>, b: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().cartesian_product(b.fuse()))
+ }
+
+ fn fused_merge(a: Iter<i16>, b: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().merge(b.fuse()))
+ }
+
+ fn fused_filter_ok(a: Iter<i16>) -> bool
+ {
+ is_fused(a.map(|x| if x % 2 == 0 {Ok(x)} else {Err(x)} )
+ .filter_ok(|x| x % 3 == 0)
+ .fuse())
+ }
+
+ fn fused_filter_map_ok(a: Iter<i16>) -> bool
+ {
+ is_fused(a.map(|x| if x % 2 == 0 {Ok(x)} else {Err(x)} )
+ .filter_map_ok(|x| if x % 3 == 0 {Some(x / 3)} else {None})
+ .fuse())
+ }
+
+ fn fused_positions(a: Iter<i16>) -> bool
+ {
+ !is_fused(a.clone().positions(|x|x%2==0)) &&
+ is_fused(a.fuse().positions(|x|x%2==0))
+ }
+
+ fn fused_update(a: Iter<i16>) -> bool
+ {
+ !is_fused(a.clone().update(|x|*x+=1)) &&
+ is_fused(a.fuse().update(|x|*x+=1))
+ }
+
+ fn fused_tuple_windows(a: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().tuple_windows::<(_,_)>())
+ }
+
+ fn fused_pad_using(a: Iter<i16>) -> bool
+ {
+ is_fused(a.fuse().pad_using(100,|_|0))
+ }
+}
+
+quickcheck! {
+ fn min_set_contains_min(a: Vec<(usize, char)>) -> bool {
+ let result_set = a.iter().min_set();
+ if let Some(result_element) = a.iter().min() {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+
+ fn min_set_by_contains_min(a: Vec<(usize, char)>) -> bool {
+ let compare = |x: &&(usize, char), y: &&(usize, char)| x.1.cmp(&y.1);
+ let result_set = a.iter().min_set_by(compare);
+ if let Some(result_element) = a.iter().min_by(compare) {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+
+ fn min_set_by_key_contains_min(a: Vec<(usize, char)>) -> bool {
+ let key = |x: &&(usize, char)| x.1;
+ let result_set = a.iter().min_set_by_key(&key);
+ if let Some(result_element) = a.iter().min_by_key(&key) {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+
+ fn max_set_contains_max(a: Vec<(usize, char)>) -> bool {
+ let result_set = a.iter().max_set();
+ if let Some(result_element) = a.iter().max() {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+
+ fn max_set_by_contains_max(a: Vec<(usize, char)>) -> bool {
+ let compare = |x: &&(usize, char), y: &&(usize, char)| x.1.cmp(&y.1);
+ let result_set = a.iter().max_set_by(compare);
+ if let Some(result_element) = a.iter().max_by(compare) {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+
+ fn max_set_by_key_contains_max(a: Vec<(usize, char)>) -> bool {
+ let key = |x: &&(usize, char)| x.1;
+ let result_set = a.iter().max_set_by_key(&key);
+ if let Some(result_element) = a.iter().max_by_key(&key) {
+ result_set.contains(&result_element)
+ } else {
+ result_set.is_empty()
+ }
+ }
+}
--- /dev/null
+use itertools::Itertools;
+use std::fmt::Debug;
+use quickcheck::quickcheck;
+
+struct Unspecialized<I>(I);
+impl<I> Iterator for Unspecialized<I>
+where
+ I: Iterator,
+{
+ type Item = I::Item;
+
+ #[inline(always)]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.0.next()
+ }
+}
+
+macro_rules! check_specialized {
+ ($src:expr, |$it:pat| $closure:expr) => {
+ let $it = $src.clone();
+ let v1 = $closure;
+
+ let $it = Unspecialized($src.clone());
+ let v2 = $closure;
+
+ assert_eq!(v1, v2);
+ }
+}
+
+fn test_specializations<IterItem, Iter>(
+ it: &Iter,
+) where
+ IterItem: Eq + Debug + Clone,
+ Iter: Iterator<Item = IterItem> + Clone,
+{
+ check_specialized!(it, |i| i.count());
+ check_specialized!(it, |i| i.last());
+ check_specialized!(it, |i| i.collect::<Vec<_>>());
+ check_specialized!(it, |i| {
+ let mut parameters_from_fold = vec![];
+ let fold_result = i.fold(vec![], |mut acc, v: IterItem| {
+ parameters_from_fold.push((acc.clone(), v.clone()));
+ acc.push(v);
+ acc
+ });
+ (parameters_from_fold, fold_result)
+ });
+ check_specialized!(it, |mut i| {
+ let mut parameters_from_all = vec![];
+ let first = i.next();
+ let all_result = i.all(|x| {
+ parameters_from_all.push(x.clone());
+ Some(x)==first
+ });
+ (parameters_from_all, all_result)
+ });
+ let size = it.clone().count();
+ for n in 0..size + 2 {
+ check_specialized!(it, |mut i| i.nth(n));
+ }
+ // size_hint is a bit harder to check
+ let mut it_sh = it.clone();
+ for n in 0..size + 2 {
+ let len = it_sh.clone().count();
+ let (min, max) = it_sh.size_hint();
+ assert_eq!(size - n.min(size), len);
+ assert!(min <= len);
+ if let Some(max) = max {
+ assert!(len <= max);
+ }
+ it_sh.next();
+ }
+}
+
+quickcheck! {
+ fn intersperse(v: Vec<u8>) -> () {
+ test_specializations(&v.into_iter().intersperse(0));
+ }
+}
+
+quickcheck! {
+ fn put_back_qc(test_vec: Vec<i32>) -> () {
+ test_specializations(&itertools::put_back(test_vec.iter()));
+ let mut pb = itertools::put_back(test_vec.into_iter());
+ pb.put_back(1);
+ test_specializations(&pb);
+ }
+}
+
+quickcheck! {
+ fn merge_join_by_qc(i1: Vec<usize>, i2: Vec<usize>) -> () {
+ test_specializations(&i1.into_iter().merge_join_by(i2.into_iter(), std::cmp::Ord::cmp));
+ }
+}
+
+quickcheck! {
+ fn map_into(v: Vec<u8>) -> () {
+ test_specializations(&v.into_iter().map_into::<u32>());
+ }
+}
+
+quickcheck! {
+ fn map_ok(v: Vec<Result<u8, char>>) -> () {
+ test_specializations(&v.into_iter().map_ok(|u| u.checked_add(1)));
+ }
+}
+
+quickcheck! {
+ fn process_results(v: Vec<Result<u8, u8>>) -> () {
+ helper(v.iter().copied());
+ helper(v.iter().copied().filter(Result::is_ok));
+
+ fn helper(it: impl Iterator<Item = Result<u8, u8>> + Clone) {
+ macro_rules! check_results_specialized {
+ ($src:expr, |$it:pat| $closure:expr) => {
+ assert_eq!(
+ itertools::process_results($src.clone(), |$it| $closure),
+ itertools::process_results($src.clone(), |i| {
+ let $it = Unspecialized(i);
+ $closure
+ }),
+ )
+ }
+ }
+
+ check_results_specialized!(it, |i| i.count());
+ check_results_specialized!(it, |i| i.last());
+ check_results_specialized!(it, |i| i.collect::<Vec<_>>());
+ check_results_specialized!(it, |i| {
+ let mut parameters_from_fold = vec![];
+ let fold_result = i.fold(vec![], |mut acc, v| {
+ parameters_from_fold.push((acc.clone(), v));
+ acc.push(v);
+ acc
+ });
+ (parameters_from_fold, fold_result)
+ });
+ check_results_specialized!(it, |mut i| {
+ let mut parameters_from_all = vec![];
+ let first = i.next();
+ let all_result = i.all(|x| {
+ parameters_from_all.push(x);
+ Some(x)==first
+ });
+ (parameters_from_all, all_result)
+ });
+ let size = it.clone().count();
+ for n in 0..size + 2 {
+ check_results_specialized!(it, |mut i| i.nth(n));
+ }
+ }
+ }
+}
--- /dev/null
+//! Licensed under the Apache License, Version 2.0
+//! https://www.apache.org/licenses/LICENSE-2.0 or the MIT license
+//! https://opensource.org/licenses/MIT, at your
+//! option. This file may not be copied, modified, or distributed
+//! except according to those terms.
+#![no_std]
+
+use core::iter;
+use itertools as it;
+use crate::it::Itertools;
+use crate::it::interleave;
+use crate::it::intersperse;
+use crate::it::intersperse_with;
+use crate::it::multizip;
+use crate::it::free::put_back;
+use crate::it::iproduct;
+use crate::it::izip;
+use crate::it::chain;
+
+#[test]
+fn product2() {
+ let s = "αβ";
+
+ let mut prod = iproduct!(s.chars(), 0..2);
+ assert!(prod.next() == Some(('α', 0)));
+ assert!(prod.next() == Some(('α', 1)));
+ assert!(prod.next() == Some(('β', 0)));
+ assert!(prod.next() == Some(('β', 1)));
+ assert!(prod.next() == None);
+}
+
+#[test]
+fn product_temporary() {
+ for (_x, _y, _z) in iproduct!(
+ [0, 1, 2].iter().cloned(),
+ [0, 1, 2].iter().cloned(),
+ [0, 1, 2].iter().cloned())
+ {
+ // ok
+ }
+}
+
+
+#[test]
+fn izip_macro() {
+ let mut zip = izip!(2..3);
+ assert!(zip.next() == Some(2));
+ assert!(zip.next().is_none());
+
+ let mut zip = izip!(0..3, 0..2, 0..2i8);
+ for i in 0..2 {
+ assert!((i as usize, i, i as i8) == zip.next().unwrap());
+ }
+ assert!(zip.next().is_none());
+
+ let xs: [isize; 0] = [];
+ let mut zip = izip!(0..3, 0..2, 0..2i8, &xs);
+ assert!(zip.next().is_none());
+}
+
+#[test]
+fn izip2() {
+ let _zip1: iter::Zip<_, _> = izip!(1.., 2..);
+ let _zip2: iter::Zip<_, _> = izip!(1.., 2.., );
+}
+
+#[test]
+fn izip3() {
+ let mut zip: iter::Map<iter::Zip<_, _>, _> = izip!(0..3, 0..2, 0..2i8);
+ for i in 0..2 {
+ assert!((i as usize, i, i as i8) == zip.next().unwrap());
+ }
+ assert!(zip.next().is_none());
+}
+
+#[test]
+fn multizip3() {
+ let mut zip = multizip((0..3, 0..2, 0..2i8));
+ for i in 0..2 {
+ assert!((i as usize, i, i as i8) == zip.next().unwrap());
+ }
+ assert!(zip.next().is_none());
+
+ let xs: [isize; 0] = [];
+ let mut zip = multizip((0..3, 0..2, 0..2i8, xs.iter()));
+ assert!(zip.next().is_none());
+
+ for (_, _, _, _, _) in multizip((0..3, 0..2, xs.iter(), &xs, xs.to_vec())) {
+ /* test compiles */
+ }
+}
+
+#[test]
+fn chain_macro() {
+ let mut chain = chain!(2..3);
+ assert!(chain.next() == Some(2));
+ assert!(chain.next().is_none());
+
+ let mut chain = chain!(0..2, 2..3, 3..5i8);
+ for i in 0..5i8 {
+ assert_eq!(Some(i), chain.next());
+ }
+ assert!(chain.next().is_none());
+
+ let mut chain = chain!();
+ assert_eq!(chain.next(), Option::<()>::None);
+}
+
+#[test]
+fn chain2() {
+ let _ = chain!(1.., 2..);
+ let _ = chain!(1.., 2.., );
+}
+
+#[test]
+fn write_to() {
+ let xs = [7, 9, 8];
+ let mut ys = [0; 5];
+ let cnt = ys.iter_mut().set_from(xs.iter().copied());
+ assert!(cnt == xs.len());
+ assert!(ys == [7, 9, 8, 0, 0]);
+
+ let cnt = ys.iter_mut().set_from(0..10);
+ assert!(cnt == ys.len());
+ assert!(ys == [0, 1, 2, 3, 4]);
+}
+
+#[test]
+fn test_interleave() {
+ let xs: [u8; 0] = [];
+ let ys = [7u8, 9, 8, 10];
+ let zs = [2u8, 77];
+ let it = interleave(xs.iter(), ys.iter());
+ it::assert_equal(it, ys.iter());
+
+ let rs = [7u8, 2, 9, 77, 8, 10];
+ let it = interleave(ys.iter(), zs.iter());
+ it::assert_equal(it, rs.iter());
+}
+
+#[test]
+fn test_intersperse() {
+ let xs = [1u8, 2, 3];
+ let ys = [1u8, 0, 2, 0, 3];
+ let it = intersperse(&xs, &0);
+ it::assert_equal(it, ys.iter());
+}
+
+#[test]
+fn test_intersperse_with() {
+ let xs = [1u8, 2, 3];
+ let ys = [1u8, 10, 2, 10, 3];
+ let i = 10;
+ let it = intersperse_with(&xs, || &i);
+ it::assert_equal(it, ys.iter());
+}
+
+#[allow(deprecated)]
+#[test]
+fn foreach() {
+ let xs = [1i32, 2, 3];
+ let mut sum = 0;
+ xs.iter().foreach(|elt| sum += *elt);
+ assert!(sum == 6);
+}
+
+#[test]
+fn dropping() {
+ let xs = [1, 2, 3];
+ let mut it = xs.iter().dropping(2);
+ assert_eq!(it.next(), Some(&3));
+ assert!(it.next().is_none());
+ let mut it = xs.iter().dropping(5);
+ assert!(it.next().is_none());
+}
+
+#[test]
+fn batching() {
+ let xs = [0, 1, 2, 1, 3];
+ let ys = [(0, 1), (2, 1)];
+
+ // An iterator that gathers elements up in pairs
+ let pit = xs
+ .iter()
+ .cloned()
+ .batching(|it| it.next().and_then(|x| it.next().map(|y| (x, y))));
+ it::assert_equal(pit, ys.iter().cloned());
+}
+
+#[test]
+fn test_put_back() {
+ let xs = [0, 1, 1, 1, 2, 1, 3, 3];
+ let mut pb = put_back(xs.iter().cloned());
+ pb.next();
+ pb.put_back(1);
+ pb.put_back(0);
+ it::assert_equal(pb, xs.iter().cloned());
+}
+
+#[allow(deprecated)]
+#[test]
+fn step() {
+ it::assert_equal((0..10).step(1), 0..10);
+ it::assert_equal((0..10).step(2), (0..10).filter(|x: &i32| *x % 2 == 0));
+ it::assert_equal((0..10).step(10), 0..1);
+}
+
+#[allow(deprecated)]
+#[test]
+fn merge() {
+ it::assert_equal((0..10).step(2).merge((1..10).step(2)), 0..10);
+}
+
+
+#[test]
+fn repeatn() {
+ let s = "α";
+ let mut it = it::repeat_n(s, 3);
+ assert_eq!(it.len(), 3);
+ assert_eq!(it.next(), Some(s));
+ assert_eq!(it.next(), Some(s));
+ assert_eq!(it.next(), Some(s));
+ assert_eq!(it.next(), None);
+ assert_eq!(it.next(), None);
+}
+
+#[test]
+fn count_clones() {
+ // Check that RepeatN only clones N - 1 times.
+
+ use core::cell::Cell;
+ #[derive(PartialEq, Debug)]
+ struct Foo {
+ n: Cell<usize>
+ }
+
+ impl Clone for Foo
+ {
+ fn clone(&self) -> Self
+ {
+ let n = self.n.get();
+ self.n.set(n + 1);
+ Foo { n: Cell::new(n + 1) }
+ }
+ }
+
+
+ for n in 0..10 {
+ let f = Foo{n: Cell::new(0)};
+ let it = it::repeat_n(f, n);
+ // drain it
+ let last = it.last();
+ if n == 0 {
+ assert_eq!(last, None);
+ } else {
+ assert_eq!(last, Some(Foo{n: Cell::new(n - 1)}));
+ }
+ }
+}
+
+#[test]
+fn part() {
+ let mut data = [7, 1, 1, 9, 1, 1, 3];
+ let i = it::partition(&mut data, |elt| *elt >= 3);
+ assert_eq!(i, 3);
+ assert_eq!(data, [7, 3, 9, 1, 1, 1, 1]);
+
+ let i = it::partition(&mut data, |elt| *elt == 1);
+ assert_eq!(i, 4);
+ assert_eq!(data, [1, 1, 1, 1, 9, 3, 7]);
+
+ let mut data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+ let i = it::partition(&mut data, |elt| *elt % 3 == 0);
+ assert_eq!(i, 3);
+ assert_eq!(data, [9, 6, 3, 4, 5, 2, 7, 8, 1]);
+}
+
+#[test]
+fn tree_fold1() {
+ for i in 0..100 {
+ assert_eq!((0..i).tree_fold1(|x, y| x + y), (0..i).fold1(|x, y| x + y));
+ }
+}
+
+#[test]
+fn exactly_one() {
+ assert_eq!((0..10).filter(|&x| x == 2).exactly_one().unwrap(), 2);
+ assert!((0..10).filter(|&x| x > 1 && x < 4).exactly_one().unwrap_err().eq(2..4));
+ assert!((0..10).filter(|&x| x > 1 && x < 5).exactly_one().unwrap_err().eq(2..5));
+ assert!((0..10).filter(|&_| false).exactly_one().unwrap_err().eq(0..0));
+}
+
+#[test]
+fn at_most_one() {
+ assert_eq!((0..10).filter(|&x| x == 2).at_most_one().unwrap(), Some(2));
+ assert!((0..10).filter(|&x| x > 1 && x < 4).at_most_one().unwrap_err().eq(2..4));
+ assert!((0..10).filter(|&x| x > 1 && x < 5).at_most_one().unwrap_err().eq(2..5));
+ assert_eq!((0..10).filter(|&_| false).at_most_one().unwrap(), None);
+}
+
+#[test]
+fn sum1() {
+ let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ assert_eq!(v[..0].iter().cloned().sum1::<i32>(), None);
+ assert_eq!(v[1..2].iter().cloned().sum1::<i32>(), Some(1));
+ assert_eq!(v[1..3].iter().cloned().sum1::<i32>(), Some(3));
+ assert_eq!(v.iter().cloned().sum1::<i32>(), Some(55));
+}
+
+#[test]
+fn product1() {
+ let v: &[i32] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ assert_eq!(v[..0].iter().cloned().product1::<i32>(), None);
+ assert_eq!(v[..1].iter().cloned().product1::<i32>(), Some(0));
+ assert_eq!(v[1..3].iter().cloned().product1::<i32>(), Some(2));
+ assert_eq!(v[1..5].iter().cloned().product1::<i32>(), Some(24));
+}
--- /dev/null
+use quickcheck as qc;
+use rand::{distributions::{Distribution, Standard}, Rng, SeedableRng, rngs::StdRng};
+use rand::{seq::SliceRandom, thread_rng};
+use std::{cmp::min, fmt::Debug, marker::PhantomData};
+use itertools as it;
+use crate::it::Itertools;
+use crate::it::ExactlyOneError;
+use crate::it::multizip;
+use crate::it::multipeek;
+use crate::it::peek_nth;
+use crate::it::free::rciter;
+use crate::it::free::put_back_n;
+use crate::it::FoldWhile;
+use crate::it::cloned;
+use crate::it::iproduct;
+use crate::it::izip;
+
+#[test]
+fn product3() {
+ let prod = iproduct!(0..3, 0..2, 0..2);
+ assert_eq!(prod.size_hint(), (12, Some(12)));
+ let v = prod.collect_vec();
+ for i in 0..3 {
+ for j in 0..2 {
+ for k in 0..2 {
+ assert!((i, j, k) == v[(i * 2 * 2 + j * 2 + k) as usize]);
+ }
+ }
+ }
+ for (_, _, _, _) in iproduct!(0..3, 0..2, 0..2, 0..3) {
+ /* test compiles */
+ }
+}
+
+#[test]
+fn interleave_shortest() {
+ let v0: Vec<i32> = vec![0, 2, 4];
+ let v1: Vec<i32> = vec![1, 3, 5, 7];
+ let it = v0.into_iter().interleave_shortest(v1.into_iter());
+ assert_eq!(it.size_hint(), (6, Some(6)));
+ assert_eq!(it.collect_vec(), vec![0, 1, 2, 3, 4, 5]);
+
+ let v0: Vec<i32> = vec![0, 2, 4, 6, 8];
+ let v1: Vec<i32> = vec![1, 3, 5];
+ let it = v0.into_iter().interleave_shortest(v1.into_iter());
+ assert_eq!(it.size_hint(), (7, Some(7)));
+ assert_eq!(it.collect_vec(), vec![0, 1, 2, 3, 4, 5, 6]);
+
+ let i0 = ::std::iter::repeat(0);
+ let v1: Vec<_> = vec![1, 3, 5];
+ let it = i0.interleave_shortest(v1.into_iter());
+ assert_eq!(it.size_hint(), (7, Some(7)));
+
+ let v0: Vec<_> = vec![0, 2, 4];
+ let i1 = ::std::iter::repeat(1);
+ let it = v0.into_iter().interleave_shortest(i1);
+ assert_eq!(it.size_hint(), (6, Some(6)));
+}
+
+#[test]
+fn duplicates_by() {
+ let xs = ["aaa", "bbbbb", "aa", "ccc", "bbbb", "aaaaa", "cccc"];
+ let ys = ["aa", "bbbb", "cccc"];
+ it::assert_equal(ys.iter(), xs.iter().duplicates_by(|x| x[..2].to_string()));
+ it::assert_equal(ys.iter(), xs.iter().rev().duplicates_by(|x| x[..2].to_string()).rev());
+ let ys_rev = ["ccc", "aa", "bbbbb"];
+ it::assert_equal(ys_rev.iter(), xs.iter().duplicates_by(|x| x[..2].to_string()).rev());
+}
+
+#[test]
+fn duplicates() {
+ let xs = [0, 1, 2, 3, 2, 1, 3];
+ let ys = [2, 1, 3];
+ it::assert_equal(ys.iter(), xs.iter().duplicates());
+ it::assert_equal(ys.iter(), xs.iter().rev().duplicates().rev());
+ let ys_rev = [3, 2, 1];
+ it::assert_equal(ys_rev.iter(), xs.iter().duplicates().rev());
+
+ let xs = [0, 1, 0, 1];
+ let ys = [0, 1];
+ it::assert_equal(ys.iter(), xs.iter().duplicates());
+ it::assert_equal(ys.iter(), xs.iter().rev().duplicates().rev());
+ let ys_rev = [1, 0];
+ it::assert_equal(ys_rev.iter(), xs.iter().duplicates().rev());
+
+ let xs = vec![0, 1, 2, 1, 2];
+ let ys = vec![1, 2];
+ assert_eq!(ys, xs.iter().duplicates().cloned().collect_vec());
+ assert_eq!(ys, xs.iter().rev().duplicates().rev().cloned().collect_vec());
+ let ys_rev = vec![2, 1];
+ assert_eq!(ys_rev, xs.iter().duplicates().rev().cloned().collect_vec());
+}
+
+#[test]
+fn unique_by() {
+ let xs = ["aaa", "bbbbb", "aa", "ccc", "bbbb", "aaaaa", "cccc"];
+ let ys = ["aaa", "bbbbb", "ccc"];
+ it::assert_equal(ys.iter(), xs.iter().unique_by(|x| x[..2].to_string()));
+ it::assert_equal(ys.iter(), xs.iter().rev().unique_by(|x| x[..2].to_string()).rev());
+ let ys_rev = ["cccc", "aaaaa", "bbbb"];
+ it::assert_equal(ys_rev.iter(), xs.iter().unique_by(|x| x[..2].to_string()).rev());
+}
+
+#[test]
+fn unique() {
+ let xs = [0, 1, 2, 3, 2, 1, 3];
+ let ys = [0, 1, 2, 3];
+ it::assert_equal(ys.iter(), xs.iter().unique());
+ it::assert_equal(ys.iter(), xs.iter().rev().unique().rev());
+ let ys_rev = [3, 1, 2, 0];
+ it::assert_equal(ys_rev.iter(), xs.iter().unique().rev());
+
+ let xs = [0, 1];
+ let ys = [0, 1];
+ it::assert_equal(ys.iter(), xs.iter().unique());
+ it::assert_equal(ys.iter(), xs.iter().rev().unique().rev());
+ let ys_rev = [1, 0];
+ it::assert_equal(ys_rev.iter(), xs.iter().unique().rev());
+}
+
+#[test]
+fn intersperse() {
+ let xs = ["a", "", "b", "c"];
+ let v: Vec<&str> = xs.iter().cloned().intersperse(", ").collect();
+ let text: String = v.concat();
+ assert_eq!(text, "a, , b, c".to_string());
+
+ let ys = [0, 1, 2, 3];
+ let mut it = ys[..0].iter().copied().intersperse(1);
+ assert!(it.next() == None);
+}
+
+#[test]
+fn dedup() {
+ let xs = [0, 1, 1, 1, 2, 1, 3, 3];
+ let ys = [0, 1, 2, 1, 3];
+ it::assert_equal(ys.iter(), xs.iter().dedup());
+ let xs = [0, 0, 0, 0, 0];
+ let ys = [0];
+ it::assert_equal(ys.iter(), xs.iter().dedup());
+
+ let xs = [0, 1, 1, 1, 2, 1, 3, 3];
+ let ys = [0, 1, 2, 1, 3];
+ let mut xs_d = Vec::new();
+ xs.iter().dedup().fold((), |(), &elt| xs_d.push(elt));
+ assert_eq!(&xs_d, &ys);
+}
+
+#[test]
+fn coalesce() {
+ let data = vec![-1., -2., -3., 3., 1., 0., -1.];
+ let it = data.iter().cloned().coalesce(|x, y|
+ if (x >= 0.) == (y >= 0.) {
+ Ok(x + y)
+ } else {
+ Err((x, y))
+ }
+ );
+ itertools::assert_equal(it.clone(), vec![-6., 4., -1.]);
+ assert_eq!(
+ it.fold(vec![], |mut v, n| {
+ v.push(n);
+ v
+ }),
+ vec![-6., 4., -1.]
+ );
+}
+
+#[test]
+fn dedup_by() {
+ let xs = [(0, 0), (0, 1), (1, 1), (2, 1), (0, 2), (3, 1), (0, 3), (1, 3)];
+ let ys = [(0, 0), (0, 1), (0, 2), (3, 1), (0, 3)];
+ it::assert_equal(ys.iter(), xs.iter().dedup_by(|x, y| x.1==y.1));
+ let xs = [(0, 1), (0, 2), (0, 3), (0, 4), (0, 5)];
+ let ys = [(0, 1)];
+ it::assert_equal(ys.iter(), xs.iter().dedup_by(|x, y| x.0==y.0));
+
+ let xs = [(0, 0), (0, 1), (1, 1), (2, 1), (0, 2), (3, 1), (0, 3), (1, 3)];
+ let ys = [(0, 0), (0, 1), (0, 2), (3, 1), (0, 3)];
+ let mut xs_d = Vec::new();
+ xs.iter().dedup_by(|x, y| x.1==y.1).fold((), |(), &elt| xs_d.push(elt));
+ assert_eq!(&xs_d, &ys);
+}
+
+#[test]
+fn dedup_with_count() {
+ let xs: [i32; 8] = [0, 1, 1, 1, 2, 1, 3, 3];
+ let ys: [(usize, &i32); 5] = [(1, &0), (3, &1), (1, &2), (1, &1), (2, &3)];
+
+ it::assert_equal(ys.iter().cloned(), xs.iter().dedup_with_count());
+
+ let xs: [i32; 5] = [0, 0, 0, 0, 0];
+ let ys: [(usize, &i32); 1] = [(5, &0)];
+
+ it::assert_equal(ys.iter().cloned(), xs.iter().dedup_with_count());
+}
+
+
+#[test]
+fn dedup_by_with_count() {
+ let xs = [(0, 0), (0, 1), (1, 1), (2, 1), (0, 2), (3, 1), (0, 3), (1, 3)];
+ let ys = [(1, &(0, 0)), (3, &(0, 1)), (1, &(0, 2)), (1, &(3, 1)), (2, &(0, 3))];
+
+ it::assert_equal(ys.iter().cloned(), xs.iter().dedup_by_with_count(|x, y| x.1==y.1));
+
+ let xs = [(0, 1), (0, 2), (0, 3), (0, 4), (0, 5)];
+ let ys = [( 5, &(0, 1))];
+
+ it::assert_equal(ys.iter().cloned(), xs.iter().dedup_by_with_count(|x, y| x.0==y.0));
+}
+
+#[test]
+fn all_equal() {
+ assert!("".chars().all_equal());
+ assert!("A".chars().all_equal());
+ assert!(!"AABBCCC".chars().all_equal());
+ assert!("AAAAAAA".chars().all_equal());
+ for (_key, mut sub) in &"AABBCCC".chars().group_by(|&x| x) {
+ assert!(sub.all_equal());
+ }
+}
+
+#[test]
+fn all_unique() {
+ assert!("ABCDEFGH".chars().all_unique());
+ assert!(!"ABCDEFGA".chars().all_unique());
+ assert!(::std::iter::empty::<usize>().all_unique());
+}
+
+#[test]
+fn test_put_back_n() {
+ let xs = [0, 1, 1, 1, 2, 1, 3, 3];
+ let mut pb = put_back_n(xs.iter().cloned());
+ pb.next();
+ pb.next();
+ pb.put_back(1);
+ pb.put_back(0);
+ it::assert_equal(pb, xs.iter().cloned());
+}
+
+#[test]
+fn tee() {
+ let xs = [0, 1, 2, 3];
+ let (mut t1, mut t2) = xs.iter().cloned().tee();
+ assert_eq!(t1.next(), Some(0));
+ assert_eq!(t2.next(), Some(0));
+ assert_eq!(t1.next(), Some(1));
+ assert_eq!(t1.next(), Some(2));
+ assert_eq!(t1.next(), Some(3));
+ assert_eq!(t1.next(), None);
+ assert_eq!(t2.next(), Some(1));
+ assert_eq!(t2.next(), Some(2));
+ assert_eq!(t1.next(), None);
+ assert_eq!(t2.next(), Some(3));
+ assert_eq!(t2.next(), None);
+ assert_eq!(t1.next(), None);
+ assert_eq!(t2.next(), None);
+
+ let (t1, t2) = xs.iter().cloned().tee();
+ it::assert_equal(t1, xs.iter().cloned());
+ it::assert_equal(t2, xs.iter().cloned());
+
+ let (t1, t2) = xs.iter().cloned().tee();
+ it::assert_equal(t1.zip(t2), xs.iter().cloned().zip(xs.iter().cloned()));
+}
+
+
+#[test]
+fn test_rciter() {
+ let xs = [0, 1, 1, 1, 2, 1, 3, 5, 6];
+
+ let mut r1 = rciter(xs.iter().cloned());
+ let mut r2 = r1.clone();
+ assert_eq!(r1.next(), Some(0));
+ assert_eq!(r2.next(), Some(1));
+ let mut z = r1.zip(r2);
+ assert_eq!(z.next(), Some((1, 1)));
+ assert_eq!(z.next(), Some((2, 1)));
+ assert_eq!(z.next(), Some((3, 5)));
+ assert_eq!(z.next(), None);
+
+ // test intoiterator
+ let r1 = rciter(0..5);
+ let mut z = izip!(&r1, r1);
+ assert_eq!(z.next(), Some((0, 1)));
+}
+
+#[allow(deprecated)]
+#[test]
+fn trait_pointers() {
+ struct ByRef<'r, I: ?Sized>(&'r mut I) ;
+
+ impl<'r, X, I: ?Sized> Iterator for ByRef<'r, I> where
+ I: 'r + Iterator<Item=X>
+ {
+ type Item = X;
+ fn next(&mut self) -> Option<Self::Item>
+ {
+ self.0.next()
+ }
+ }
+
+ let mut it = Box::new(0..10) as Box<dyn Iterator<Item=i32>>;
+ assert_eq!(it.next(), Some(0));
+
+ {
+ /* make sure foreach works on non-Sized */
+ let jt: &mut dyn Iterator<Item = i32> = &mut *it;
+ assert_eq!(jt.next(), Some(1));
+
+ {
+ let mut r = ByRef(jt);
+ assert_eq!(r.next(), Some(2));
+ }
+
+ assert_eq!(jt.find_position(|x| *x == 4), Some((1, 4)));
+ jt.foreach(|_| ());
+ }
+}
+
+#[test]
+fn merge_by() {
+ let odd : Vec<(u32, &str)> = vec![(1, "hello"), (3, "world"), (5, "!")];
+ let even = vec![(2, "foo"), (4, "bar"), (6, "baz")];
+ let expected = vec![(1, "hello"), (2, "foo"), (3, "world"), (4, "bar"), (5, "!"), (6, "baz")];
+ let results = odd.iter().merge_by(even.iter(), |a, b| a.0 <= b.0);
+ it::assert_equal(results, expected.iter());
+}
+
+#[test]
+fn merge_by_btree() {
+ use std::collections::BTreeMap;
+ let mut bt1 = BTreeMap::new();
+ bt1.insert("hello", 1);
+ bt1.insert("world", 3);
+ let mut bt2 = BTreeMap::new();
+ bt2.insert("foo", 2);
+ bt2.insert("bar", 4);
+ let results = bt1.into_iter().merge_by(bt2.into_iter(), |a, b| a.0 <= b.0 );
+ let expected = vec![("bar", 4), ("foo", 2), ("hello", 1), ("world", 3)];
+ it::assert_equal(results, expected.into_iter());
+}
+
+#[allow(deprecated)]
+#[test]
+fn kmerge() {
+ let its = (0..4).map(|s| (s..10).step(4));
+
+ it::assert_equal(its.kmerge(), 0..10);
+}
+
+#[allow(deprecated)]
+#[test]
+fn kmerge_2() {
+ let its = vec![3, 2, 1, 0].into_iter().map(|s| (s..10).step(4));
+
+ it::assert_equal(its.kmerge(), 0..10);
+}
+
+#[test]
+fn kmerge_empty() {
+ let its = (0..4).map(|_| 0..0);
+ assert_eq!(its.kmerge().next(), None);
+}
+
+#[test]
+fn kmerge_size_hint() {
+ let its = (0..5).map(|_| (0..10));
+ assert_eq!(its.kmerge().size_hint(), (50, Some(50)));
+}
+
+#[test]
+fn kmerge_empty_size_hint() {
+ let its = (0..5).map(|_| (0..0));
+ assert_eq!(its.kmerge().size_hint(), (0, Some(0)));
+}
+
+#[test]
+fn join() {
+ let many = [1, 2, 3];
+ let one = [1];
+ let none: Vec<i32> = vec![];
+
+ assert_eq!(many.iter().join(", "), "1, 2, 3");
+ assert_eq!( one.iter().join(", "), "1");
+ assert_eq!(none.iter().join(", "), "");
+}
+
+#[test]
+fn sorted_unstable_by() {
+ let sc = [3, 4, 1, 2].iter().cloned().sorted_by(|&a, &b| {
+ a.cmp(&b)
+ });
+ it::assert_equal(sc, vec![1, 2, 3, 4]);
+
+ let v = (0..5).sorted_unstable_by(|&a, &b| a.cmp(&b).reverse());
+ it::assert_equal(v, vec![4, 3, 2, 1, 0]);
+}
+
+#[test]
+fn sorted_unstable_by_key() {
+ let sc = [3, 4, 1, 2].iter().cloned().sorted_unstable_by_key(|&x| x);
+ it::assert_equal(sc, vec![1, 2, 3, 4]);
+
+ let v = (0..5).sorted_unstable_by_key(|&x| -x);
+ it::assert_equal(v, vec![4, 3, 2, 1, 0]);
+}
+
+#[test]
+fn sorted_by() {
+ let sc = [3, 4, 1, 2].iter().cloned().sorted_by(|&a, &b| {
+ a.cmp(&b)
+ });
+ it::assert_equal(sc, vec![1, 2, 3, 4]);
+
+ let v = (0..5).sorted_by(|&a, &b| a.cmp(&b).reverse());
+ it::assert_equal(v, vec![4, 3, 2, 1, 0]);
+}
+
+qc::quickcheck! {
+ fn k_smallest_range(n: u64, m: u16, k: u16) -> () {
+ // u16 is used to constrain k and m to 0..2¹⁶,
+ // otherwise the test could use too much memory.
+ let (k, m) = (k as u64, m as u64);
+
+ // Generate a random permutation of n..n+m
+ let i = {
+ let mut v: Vec<u64> = (n..n.saturating_add(m)).collect();
+ v.shuffle(&mut thread_rng());
+ v.into_iter()
+ };
+
+ // Check that taking the k smallest elements yields n..n+min(k, m)
+ it::assert_equal(
+ i.k_smallest(k as usize),
+ n..n.saturating_add(min(k, m))
+ );
+ }
+}
+
+#[derive(Clone, Debug)]
+struct RandIter<T: 'static + Clone + Send, R: 'static + Clone + Rng + SeedableRng + Send = StdRng> {
+ idx: usize,
+ len: usize,
+ rng: R,
+ _t: PhantomData<T>
+}
+
+impl<T: Clone + Send, R: Clone + Rng + SeedableRng + Send> Iterator for RandIter<T, R>
+where Standard: Distribution<T> {
+ type Item = T;
+ fn next(&mut self) -> Option<T> {
+ if self.idx == self.len {
+ None
+ } else {
+ self.idx += 1;
+ Some(self.rng.gen())
+ }
+ }
+}
+
+impl<T: Clone + Send, R: Clone + Rng + SeedableRng + Send> qc::Arbitrary for RandIter<T, R> {
+ fn arbitrary<G: qc::Gen>(g: &mut G) -> Self {
+ RandIter {
+ idx: 0,
+ len: g.size(),
+ rng: R::seed_from_u64(g.next_u64()),
+ _t : PhantomData{},
+ }
+ }
+}
+
+// Check that taking the k smallest is the same as
+// sorting then taking the k first elements
+fn k_smallest_sort<I>(i: I, k: u16)
+where
+ I: Iterator + Clone,
+ I::Item: Ord + Debug,
+{
+ let j = i.clone();
+ let k = k as usize;
+ it::assert_equal(
+ i.k_smallest(k),
+ j.sorted().take(k)
+ )
+}
+
+macro_rules! generic_test {
+ ($f:ident, $($t:ty),+) => {
+ $(paste::item! {
+ qc::quickcheck! {
+ fn [< $f _ $t >](i: RandIter<$t>, k: u16) -> () {
+ $f(i, k)
+ }
+ }
+ })+
+ };
+}
+
+generic_test!(k_smallest_sort, u8, u16, u32, u64, i8, i16, i32, i64);
+
+#[test]
+fn sorted_by_key() {
+ let sc = [3, 4, 1, 2].iter().cloned().sorted_by_key(|&x| x);
+ it::assert_equal(sc, vec![1, 2, 3, 4]);
+
+ let v = (0..5).sorted_by_key(|&x| -x);
+ it::assert_equal(v, vec![4, 3, 2, 1, 0]);
+}
+
+#[test]
+fn sorted_by_cached_key() {
+ // Track calls to key function
+ let mut ncalls = 0;
+
+ let sorted = [3, 4, 1, 2].iter().cloned().sorted_by_cached_key(|&x| {
+ ncalls += 1;
+ x.to_string()
+ });
+ it::assert_equal(sorted, vec![1, 2, 3, 4]);
+ // Check key function called once per element
+ assert_eq!(ncalls, 4);
+
+ let mut ncalls = 0;
+
+ let sorted = (0..5).sorted_by_cached_key(|&x| {
+ ncalls += 1;
+ -x
+ });
+ it::assert_equal(sorted, vec![4, 3, 2, 1, 0]);
+ // Check key function called once per element
+ assert_eq!(ncalls, 5);
+}
+
+#[test]
+fn test_multipeek() {
+ let nums = vec![1u8,2,3,4,5];
+
+ let mp = multipeek(nums.iter().copied());
+ assert_eq!(nums, mp.collect::<Vec<_>>());
+
+ let mut mp = multipeek(nums.iter().copied());
+ assert_eq!(mp.peek(), Some(&1));
+ assert_eq!(mp.next(), Some(1));
+ assert_eq!(mp.peek(), Some(&2));
+ assert_eq!(mp.peek(), Some(&3));
+ assert_eq!(mp.next(), Some(2));
+ assert_eq!(mp.peek(), Some(&3));
+ assert_eq!(mp.peek(), Some(&4));
+ assert_eq!(mp.peek(), Some(&5));
+ assert_eq!(mp.peek(), None);
+ assert_eq!(mp.next(), Some(3));
+ assert_eq!(mp.next(), Some(4));
+ assert_eq!(mp.peek(), Some(&5));
+ assert_eq!(mp.peek(), None);
+ assert_eq!(mp.next(), Some(5));
+ assert_eq!(mp.next(), None);
+ assert_eq!(mp.peek(), None);
+}
+
+#[test]
+fn test_multipeek_reset() {
+ let data = [1, 2, 3, 4];
+
+ let mut mp = multipeek(cloned(&data));
+ assert_eq!(mp.peek(), Some(&1));
+ assert_eq!(mp.next(), Some(1));
+ assert_eq!(mp.peek(), Some(&2));
+ assert_eq!(mp.peek(), Some(&3));
+ mp.reset_peek();
+ assert_eq!(mp.peek(), Some(&2));
+ assert_eq!(mp.next(), Some(2));
+}
+
+#[test]
+fn test_multipeek_peeking_next() {
+ use crate::it::PeekingNext;
+ let nums = vec![1u8,2,3,4,5,6,7];
+
+ let mut mp = multipeek(nums.iter().copied());
+ assert_eq!(mp.peeking_next(|&x| x != 0), Some(1));
+ assert_eq!(mp.next(), Some(2));
+ assert_eq!(mp.peek(), Some(&3));
+ assert_eq!(mp.peek(), Some(&4));
+ assert_eq!(mp.peeking_next(|&x| x == 3), Some(3));
+ assert_eq!(mp.peek(), Some(&4));
+ assert_eq!(mp.peeking_next(|&x| x != 4), None);
+ assert_eq!(mp.peeking_next(|&x| x == 4), Some(4));
+ assert_eq!(mp.peek(), Some(&5));
+ assert_eq!(mp.peek(), Some(&6));
+ assert_eq!(mp.peeking_next(|&x| x != 5), None);
+ assert_eq!(mp.peek(), Some(&7));
+ assert_eq!(mp.peeking_next(|&x| x == 5), Some(5));
+ assert_eq!(mp.peeking_next(|&x| x == 6), Some(6));
+ assert_eq!(mp.peek(), Some(&7));
+ assert_eq!(mp.peek(), None);
+ assert_eq!(mp.next(), Some(7));
+ assert_eq!(mp.peek(), None);
+}
+
+#[test]
+fn test_peek_nth() {
+ let nums = vec![1u8,2,3,4,5];
+
+ let iter = peek_nth(nums.iter().copied());
+ assert_eq!(nums, iter.collect::<Vec<_>>());
+
+ let mut iter = peek_nth(nums.iter().copied());
+
+ assert_eq!(iter.peek_nth(0), Some(&1));
+ assert_eq!(iter.peek_nth(0), Some(&1));
+ assert_eq!(iter.next(), Some(1));
+
+ assert_eq!(iter.peek_nth(0), Some(&2));
+ assert_eq!(iter.peek_nth(1), Some(&3));
+ assert_eq!(iter.next(), Some(2));
+
+ assert_eq!(iter.peek_nth(0), Some(&3));
+ assert_eq!(iter.peek_nth(1), Some(&4));
+ assert_eq!(iter.peek_nth(2), Some(&5));
+ assert_eq!(iter.peek_nth(3), None);
+
+ assert_eq!(iter.next(), Some(3));
+ assert_eq!(iter.next(), Some(4));
+
+ assert_eq!(iter.peek_nth(0), Some(&5));
+ assert_eq!(iter.peek_nth(1), None);
+ assert_eq!(iter.next(), Some(5));
+ assert_eq!(iter.next(), None);
+
+ assert_eq!(iter.peek_nth(0), None);
+ assert_eq!(iter.peek_nth(1), None);
+}
+
+#[test]
+fn test_peek_nth_peeking_next() {
+ use it::PeekingNext;
+ let nums = vec![1u8,2,3,4,5,6,7];
+ let mut iter = peek_nth(nums.iter().copied());
+
+ assert_eq!(iter.peeking_next(|&x| x != 0), Some(1));
+ assert_eq!(iter.next(), Some(2));
+
+ assert_eq!(iter.peek_nth(0), Some(&3));
+ assert_eq!(iter.peek_nth(1), Some(&4));
+ assert_eq!(iter.peeking_next(|&x| x == 3), Some(3));
+ assert_eq!(iter.peek(), Some(&4));
+
+ assert_eq!(iter.peeking_next(|&x| x != 4), None);
+ assert_eq!(iter.peeking_next(|&x| x == 4), Some(4));
+ assert_eq!(iter.peek_nth(0), Some(&5));
+ assert_eq!(iter.peek_nth(1), Some(&6));
+
+ assert_eq!(iter.peeking_next(|&x| x != 5), None);
+ assert_eq!(iter.peek(), Some(&5));
+
+ assert_eq!(iter.peeking_next(|&x| x == 5), Some(5));
+ assert_eq!(iter.peeking_next(|&x| x == 6), Some(6));
+ assert_eq!(iter.peek_nth(0), Some(&7));
+ assert_eq!(iter.peek_nth(1), None);
+ assert_eq!(iter.next(), Some(7));
+ assert_eq!(iter.peek(), None);
+}
+
+#[test]
+fn pad_using() {
+ it::assert_equal((0..0).pad_using(1, |_| 1), 1..2);
+
+ let v: Vec<usize> = vec![0, 1, 2];
+ let r = v.into_iter().pad_using(5, |n| n);
+ it::assert_equal(r, vec![0, 1, 2, 3, 4]);
+
+ let v: Vec<usize> = vec![0, 1, 2];
+ let r = v.into_iter().pad_using(1, |_| panic!());
+ it::assert_equal(r, vec![0, 1, 2]);
+}
+
+#[test]
+fn group_by() {
+ for (ch1, sub) in &"AABBCCC".chars().group_by(|&x| x) {
+ for ch2 in sub {
+ assert_eq!(ch1, ch2);
+ }
+ }
+
+ for (ch1, sub) in &"AAABBBCCCCDDDD".chars().group_by(|&x| x) {
+ for ch2 in sub {
+ assert_eq!(ch1, ch2);
+ if ch1 == 'C' {
+ break;
+ }
+ }
+ }
+
+ let toupper = |ch: &char| ch.to_uppercase().next().unwrap();
+
+ // try all possible orderings
+ for indices in permutohedron::Heap::new(&mut [0, 1, 2, 3]) {
+ let groups = "AaaBbbccCcDDDD".chars().group_by(&toupper);
+ let mut subs = groups.into_iter().collect_vec();
+
+ for &idx in &indices[..] {
+ let (key, text) = match idx {
+ 0 => ('A', "Aaa".chars()),
+ 1 => ('B', "Bbb".chars()),
+ 2 => ('C', "ccCc".chars()),
+ 3 => ('D', "DDDD".chars()),
+ _ => unreachable!(),
+ };
+ assert_eq!(key, subs[idx].0);
+ it::assert_equal(&mut subs[idx].1, text);
+ }
+ }
+
+ let groups = "AAABBBCCCCDDDD".chars().group_by(|&x| x);
+ let mut subs = groups.into_iter().map(|(_, g)| g).collect_vec();
+
+ let sd = subs.pop().unwrap();
+ let sc = subs.pop().unwrap();
+ let sb = subs.pop().unwrap();
+ let sa = subs.pop().unwrap();
+ for (a, b, c, d) in multizip((sa, sb, sc, sd)) {
+ assert_eq!(a, 'A');
+ assert_eq!(b, 'B');
+ assert_eq!(c, 'C');
+ assert_eq!(d, 'D');
+ }
+
+ // check that the key closure is called exactly n times
+ {
+ let mut ntimes = 0;
+ let text = "AABCCC";
+ for (_, sub) in &text.chars().group_by(|&x| { ntimes += 1; x}) {
+ for _ in sub {
+ }
+ }
+ assert_eq!(ntimes, text.len());
+ }
+
+ {
+ let mut ntimes = 0;
+ let text = "AABCCC";
+ for _ in &text.chars().group_by(|&x| { ntimes += 1; x}) {
+ }
+ assert_eq!(ntimes, text.len());
+ }
+
+ {
+ let text = "ABCCCDEEFGHIJJKK";
+ let gr = text.chars().group_by(|&x| x);
+ it::assert_equal(gr.into_iter().flat_map(|(_, sub)| sub), text.chars());
+ }
+}
+
+#[test]
+fn group_by_lazy_2() {
+ let data = vec![0, 1];
+ let groups = data.iter().group_by(|k| *k);
+ let gs = groups.into_iter().collect_vec();
+ it::assert_equal(data.iter(), gs.into_iter().flat_map(|(_k, g)| g));
+
+ let data = vec![0, 1, 1, 0, 0];
+ let groups = data.iter().group_by(|k| *k);
+ let mut gs = groups.into_iter().collect_vec();
+ gs[1..].reverse();
+ it::assert_equal(&[0, 0, 0, 1, 1], gs.into_iter().flat_map(|(_, g)| g));
+
+ let grouper = data.iter().group_by(|k| *k);
+ let mut groups = Vec::new();
+ for (k, group) in &grouper {
+ if *k == 1 {
+ groups.push(group);
+ }
+ }
+ it::assert_equal(&mut groups[0], &[1, 1]);
+
+ let data = vec![0, 0, 0, 1, 1, 0, 0, 2, 2, 3, 3];
+ let grouper = data.iter().group_by(|k| *k);
+ let mut groups = Vec::new();
+ for (i, (_, group)) in grouper.into_iter().enumerate() {
+ if i < 2 {
+ groups.push(group);
+ } else if i < 4 {
+ for _ in group {
+ }
+ } else {
+ groups.push(group);
+ }
+ }
+ it::assert_equal(&mut groups[0], &[0, 0, 0]);
+ it::assert_equal(&mut groups[1], &[1, 1]);
+ it::assert_equal(&mut groups[2], &[3, 3]);
+
+ // use groups as chunks
+ let data = vec![0, 0, 0, 1, 1, 0, 0, 2, 2, 3, 3];
+ let mut i = 0;
+ let grouper = data.iter().group_by(move |_| { let k = i / 3; i += 1; k });
+ for (i, group) in &grouper {
+ match i {
+ 0 => it::assert_equal(group, &[0, 0, 0]),
+ 1 => it::assert_equal(group, &[1, 1, 0]),
+ 2 => it::assert_equal(group, &[0, 2, 2]),
+ 3 => it::assert_equal(group, &[3, 3]),
+ _ => unreachable!(),
+ }
+ }
+}
+
+#[test]
+fn group_by_lazy_3() {
+ // test consuming each group on the lap after it was produced
+ let data = vec![0, 0, 0, 1, 1, 0, 0, 1, 1, 2, 2];
+ let grouper = data.iter().group_by(|elt| *elt);
+ let mut last = None;
+ for (key, group) in &grouper {
+ if let Some(gr) = last.take() {
+ for elt in gr {
+ assert!(elt != key && i32::abs(elt - key) == 1);
+ }
+ }
+ last = Some(group);
+ }
+}
+
+#[test]
+fn chunks() {
+ let data = vec![0, 0, 0, 1, 1, 0, 0, 2, 2, 3, 3];
+ let grouper = data.iter().chunks(3);
+ for (i, chunk) in grouper.into_iter().enumerate() {
+ match i {
+ 0 => it::assert_equal(chunk, &[0, 0, 0]),
+ 1 => it::assert_equal(chunk, &[1, 1, 0]),
+ 2 => it::assert_equal(chunk, &[0, 2, 2]),
+ 3 => it::assert_equal(chunk, &[3, 3]),
+ _ => unreachable!(),
+ }
+ }
+}
+
+#[test]
+fn concat_empty() {
+ let data: Vec<Vec<()>> = Vec::new();
+ assert_eq!(data.into_iter().concat(), Vec::new())
+}
+
+#[test]
+fn concat_non_empty() {
+ let data = vec![vec![1,2,3], vec![4,5,6], vec![7,8,9]];
+ assert_eq!(data.into_iter().concat(), vec![1,2,3,4,5,6,7,8,9])
+}
+
+#[test]
+fn combinations() {
+ assert!((1..3).combinations(5).next().is_none());
+
+ let it = (1..3).combinations(2);
+ it::assert_equal(it, vec![
+ vec![1, 2],
+ ]);
+
+ let it = (1..5).combinations(2);
+ it::assert_equal(it, vec![
+ vec![1, 2],
+ vec![1, 3],
+ vec![1, 4],
+ vec![2, 3],
+ vec![2, 4],
+ vec![3, 4],
+ ]);
+
+ it::assert_equal((0..0).tuple_combinations::<(_, _)>(), <Vec<_>>::new());
+ it::assert_equal((0..1).tuple_combinations::<(_, _)>(), <Vec<_>>::new());
+ it::assert_equal((0..2).tuple_combinations::<(_, _)>(), vec![(0, 1)]);
+
+ it::assert_equal((0..0).combinations(2), <Vec<Vec<_>>>::new());
+ it::assert_equal((0..1).combinations(1), vec![vec![0]]);
+ it::assert_equal((0..2).combinations(1), vec![vec![0], vec![1]]);
+ it::assert_equal((0..2).combinations(2), vec![vec![0, 1]]);
+}
+
+#[test]
+fn combinations_of_too_short() {
+ for i in 1..10 {
+ assert!((0..0).combinations(i).next().is_none());
+ assert!((0..i - 1).combinations(i).next().is_none());
+ }
+}
+
+
+#[test]
+fn combinations_zero() {
+ it::assert_equal((1..3).combinations(0), vec![vec![]]);
+ it::assert_equal((0..0).combinations(0), vec![vec![]]);
+}
+
+#[test]
+fn permutations_zero() {
+ it::assert_equal((1..3).permutations(0), vec![vec![]]);
+ it::assert_equal((0..0).permutations(0), vec![vec![]]);
+}
+
+#[test]
+fn combinations_with_replacement() {
+ // Pool smaller than n
+ it::assert_equal((0..1).combinations_with_replacement(2), vec![vec![0, 0]]);
+ // Pool larger than n
+ it::assert_equal(
+ (0..3).combinations_with_replacement(2),
+ vec![
+ vec![0, 0],
+ vec![0, 1],
+ vec![0, 2],
+ vec![1, 1],
+ vec![1, 2],
+ vec![2, 2],
+ ],
+ );
+ // Zero size
+ it::assert_equal(
+ (0..3).combinations_with_replacement(0),
+ vec![vec![]],
+ );
+ // Zero size on empty pool
+ it::assert_equal(
+ (0..0).combinations_with_replacement(0),
+ vec![vec![]],
+ );
+ // Empty pool
+ it::assert_equal(
+ (0..0).combinations_with_replacement(2),
+ <Vec<Vec<_>>>::new(),
+ );
+}
+
+#[test]
+fn powerset() {
+ it::assert_equal((0..0).powerset(), vec![vec![]]);
+ it::assert_equal((0..1).powerset(), vec![vec![], vec![0]]);
+ it::assert_equal((0..2).powerset(), vec![vec![], vec![0], vec![1], vec![0, 1]]);
+ it::assert_equal((0..3).powerset(), vec![
+ vec![],
+ vec![0], vec![1], vec![2],
+ vec![0, 1], vec![0, 2], vec![1, 2],
+ vec![0, 1, 2]
+ ]);
+
+ assert_eq!((0..4).powerset().count(), 1 << 4);
+ assert_eq!((0..8).powerset().count(), 1 << 8);
+ assert_eq!((0..16).powerset().count(), 1 << 16);
+}
+
+#[test]
+fn diff_mismatch() {
+ let a = vec![1, 2, 3, 4];
+ let b = vec![1.0, 5.0, 3.0, 4.0];
+ let b_map = b.into_iter().map(|f| f as i32);
+ let diff = it::diff_with(a.iter(), b_map, |a, b| *a == b);
+
+ assert!(match diff {
+ Some(it::Diff::FirstMismatch(1, _, from_diff)) =>
+ from_diff.collect::<Vec<_>>() == vec![5, 3, 4],
+ _ => false,
+ });
+}
+
+#[test]
+fn diff_longer() {
+ let a = vec![1, 2, 3, 4];
+ let b = vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0];
+ let b_map = b.into_iter().map(|f| f as i32);
+ let diff = it::diff_with(a.iter(), b_map, |a, b| *a == b);
+
+ assert!(match diff {
+ Some(it::Diff::Longer(_, remaining)) =>
+ remaining.collect::<Vec<_>>() == vec![5, 6],
+ _ => false,
+ });
+}
+
+#[test]
+fn diff_shorter() {
+ let a = vec![1, 2, 3, 4];
+ let b = vec![1.0, 2.0];
+ let b_map = b.into_iter().map(|f| f as i32);
+ let diff = it::diff_with(a.iter(), b_map, |a, b| *a == b);
+
+ assert!(match diff {
+ Some(it::Diff::Shorter(len, _)) => len == 2,
+ _ => false,
+ });
+}
+
+#[test]
+fn extrema_set() {
+ use std::cmp::Ordering;
+
+ // A peculiar type: Equality compares both tuple items, but ordering only the
+ // first item. Used to distinguish equal elements.
+ #[derive(Clone, Debug, PartialEq, Eq)]
+ struct Val(u32, u32);
+
+ impl PartialOrd<Val> for Val {
+ fn partial_cmp(&self, other: &Val) -> Option<Ordering> {
+ self.0.partial_cmp(&other.0)
+ }
+ }
+
+ impl Ord for Val {
+ fn cmp(&self, other: &Val) -> Ordering {
+ self.0.cmp(&other.0)
+ }
+ }
+
+ assert_eq!(None::<u32>.iter().min_set(), Vec::<&u32>::new());
+ assert_eq!(None::<u32>.iter().max_set(), Vec::<&u32>::new());
+
+ assert_eq!(Some(1u32).iter().min_set(), vec![&1]);
+ assert_eq!(Some(1u32).iter().max_set(), vec![&1]);
+
+ let data = vec![Val(0, 1), Val(2, 0), Val(0, 2), Val(1, 0), Val(2, 1)];
+
+ let min_set = data.iter().min_set();
+ assert_eq!(min_set, vec![&Val(0, 1), &Val(0, 2)]);
+
+ let min_set_by_key = data.iter().min_set_by_key(|v| v.1);
+ assert_eq!(min_set_by_key, vec![&Val(2, 0), &Val(1, 0)]);
+
+ let min_set_by = data.iter().min_set_by(|x, y| x.1.cmp(&y.1));
+ assert_eq!(min_set_by, vec![&Val(2, 0), &Val(1, 0)]);
+
+ let max_set = data.iter().max_set();
+ assert_eq!(max_set, vec![&Val(2, 0), &Val(2, 1)]);
+
+ let max_set_by_key = data.iter().max_set_by_key(|v| v.1);
+ assert_eq!(max_set_by_key, vec![&Val(0, 2)]);
+
+ let max_set_by = data.iter().max_set_by(|x, y| x.1.cmp(&y.1));
+ assert_eq!(max_set_by, vec![&Val(0, 2)]);
+}
+
+#[test]
+fn minmax() {
+ use std::cmp::Ordering;
+ use crate::it::MinMaxResult;
+
+ // A peculiar type: Equality compares both tuple items, but ordering only the
+ // first item. This is so we can check the stability property easily.
+ #[derive(Clone, Debug, PartialEq, Eq)]
+ struct Val(u32, u32);
+
+ impl PartialOrd<Val> for Val {
+ fn partial_cmp(&self, other: &Val) -> Option<Ordering> {
+ self.0.partial_cmp(&other.0)
+ }
+ }
+
+ impl Ord for Val {
+ fn cmp(&self, other: &Val) -> Ordering {
+ self.0.cmp(&other.0)
+ }
+ }
+
+ assert_eq!(None::<Option<u32>>.iter().minmax(), MinMaxResult::NoElements);
+
+ assert_eq!(Some(1u32).iter().minmax(), MinMaxResult::OneElement(&1));
+
+ let data = vec![Val(0, 1), Val(2, 0), Val(0, 2), Val(1, 0), Val(2, 1)];
+
+ let minmax = data.iter().minmax();
+ assert_eq!(minmax, MinMaxResult::MinMax(&Val(0, 1), &Val(2, 1)));
+
+ let (min, max) = data.iter().minmax_by_key(|v| v.1).into_option().unwrap();
+ assert_eq!(min, &Val(2, 0));
+ assert_eq!(max, &Val(0, 2));
+
+ let (min, max) = data.iter().minmax_by(|x, y| x.1.cmp(&y.1)).into_option().unwrap();
+ assert_eq!(min, &Val(2, 0));
+ assert_eq!(max, &Val(0, 2));
+}
+
+#[test]
+fn format() {
+ let data = [0, 1, 2, 3];
+ let ans1 = "0, 1, 2, 3";
+ let ans2 = "0--1--2--3";
+
+ let t1 = format!("{}", data.iter().format(", "));
+ assert_eq!(t1, ans1);
+ let t2 = format!("{:?}", data.iter().format("--"));
+ assert_eq!(t2, ans2);
+
+ let dataf = [1.1, 5.71828, -22.];
+ let t3 = format!("{:.2e}", dataf.iter().format(", "));
+ assert_eq!(t3, "1.10e0, 5.72e0, -2.20e1");
+}
+
+#[test]
+fn while_some() {
+ let ns = (1..10).map(|x| if x % 5 != 0 { Some(x) } else { None })
+ .while_some();
+ it::assert_equal(ns, vec![1, 2, 3, 4]);
+}
+
+#[allow(deprecated)]
+#[test]
+fn fold_while() {
+ let mut iterations = 0;
+ let vec = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+ let sum = vec.into_iter().fold_while(0, |acc, item| {
+ iterations += 1;
+ let new_sum = acc + item;
+ if new_sum <= 20 {
+ FoldWhile::Continue(new_sum)
+ } else {
+ FoldWhile::Done(acc)
+ }
+ }).into_inner();
+ assert_eq!(iterations, 6);
+ assert_eq!(sum, 15);
+}
+
+#[test]
+fn tree_fold1() {
+ let x = [
+ "",
+ "0",
+ "0 1 x",
+ "0 1 x 2 x",
+ "0 1 x 2 3 x x",
+ "0 1 x 2 3 x x 4 x",
+ "0 1 x 2 3 x x 4 5 x x",
+ "0 1 x 2 3 x x 4 5 x 6 x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 11 x x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 11 x x 12 x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 11 x x 12 13 x x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 11 x x 12 13 x 14 x x x",
+ "0 1 x 2 3 x x 4 5 x 6 7 x x x 8 9 x 10 11 x x 12 13 x 14 15 x x x x",
+ ];
+ for (i, &s) in x.iter().enumerate() {
+ let expected = if s.is_empty() { None } else { Some(s.to_string()) };
+ let num_strings = (0..i).map(|x| x.to_string());
+ let actual = num_strings.tree_fold1(|a, b| format!("{} {} x", a, b));
+ assert_eq!(actual, expected);
+ }
+}
+
+#[test]
+fn exactly_one_question_mark_syntax_works() {
+ exactly_one_question_mark_return().unwrap_err();
+}
+
+fn exactly_one_question_mark_return() -> Result<(), ExactlyOneError<std::slice::Iter<'static, ()>>> {
+ [].iter().exactly_one()?;
+ Ok(())
+}
+
+#[test]
+fn multiunzip() {
+ let (a, b, c): (Vec<_>, Vec<_>, Vec<_>) = [(0, 1, 2), (3, 4, 5), (6, 7, 8)].iter().cloned().multiunzip();
+ assert_eq!((a, b, c), (vec![0, 3, 6], vec![1, 4, 7], vec![2, 5, 8]));
+ let (): () = [(), (), ()].iter().cloned().multiunzip();
+ let t: (Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>, Vec<_>) = [(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)].iter().cloned().multiunzip();
+ assert_eq!(t, (vec![0], vec![1], vec![2], vec![3], vec![4], vec![5], vec![6], vec![7], vec![8], vec![9], vec![10], vec![11]));
+}
--- /dev/null
+use itertools::Itertools;
+
+#[test]
+fn tuples() {
+ let v = [1, 2, 3, 4, 5];
+ let mut iter = v.iter().cloned().tuples();
+ assert_eq!(Some((1,)), iter.next());
+ assert_eq!(Some((2,)), iter.next());
+ assert_eq!(Some((3,)), iter.next());
+ assert_eq!(Some((4,)), iter.next());
+ assert_eq!(Some((5,)), iter.next());
+ assert_eq!(None, iter.next());
+ assert_eq!(None, iter.into_buffer().next());
+
+ let mut iter = v.iter().cloned().tuples();
+ assert_eq!(Some((1, 2)), iter.next());
+ assert_eq!(Some((3, 4)), iter.next());
+ assert_eq!(None, iter.next());
+ itertools::assert_equal(vec![5], iter.into_buffer());
+
+ let mut iter = v.iter().cloned().tuples();
+ assert_eq!(Some((1, 2, 3)), iter.next());
+ assert_eq!(None, iter.next());
+ itertools::assert_equal(vec![4, 5], iter.into_buffer());
+
+ let mut iter = v.iter().cloned().tuples();
+ assert_eq!(Some((1, 2, 3, 4)), iter.next());
+ assert_eq!(None, iter.next());
+ itertools::assert_equal(vec![5], iter.into_buffer());
+}
+
+#[test]
+fn tuple_windows() {
+ let v = [1, 2, 3, 4, 5];
+
+ let mut iter = v.iter().cloned().tuple_windows();
+ assert_eq!(Some((1,)), iter.next());
+ assert_eq!(Some((2,)), iter.next());
+ assert_eq!(Some((3,)), iter.next());
+
+ let mut iter = v.iter().cloned().tuple_windows();
+ assert_eq!(Some((1, 2)), iter.next());
+ assert_eq!(Some((2, 3)), iter.next());
+ assert_eq!(Some((3, 4)), iter.next());
+ assert_eq!(Some((4, 5)), iter.next());
+ assert_eq!(None, iter.next());
+
+ let mut iter = v.iter().cloned().tuple_windows();
+ assert_eq!(Some((1, 2, 3)), iter.next());
+ assert_eq!(Some((2, 3, 4)), iter.next());
+ assert_eq!(Some((3, 4, 5)), iter.next());
+ assert_eq!(None, iter.next());
+
+ let mut iter = v.iter().cloned().tuple_windows();
+ assert_eq!(Some((1, 2, 3, 4)), iter.next());
+ assert_eq!(Some((2, 3, 4, 5)), iter.next());
+ assert_eq!(None, iter.next());
+
+ let v = [1, 2, 3];
+ let mut iter = v.iter().cloned().tuple_windows::<(_, _, _, _)>();
+ assert_eq!(None, iter.next());
+}
+
+#[test]
+fn next_tuple() {
+ let v = [1, 2, 3, 4, 5];
+ let mut iter = v.iter();
+ assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((1, 2)));
+ assert_eq!(iter.next_tuple().map(|(&x, &y)| (x, y)), Some((3, 4)));
+ assert_eq!(iter.next_tuple::<(_, _)>(), None);
+}
+
+#[test]
+fn collect_tuple() {
+ let v = [1, 2];
+ let iter = v.iter().cloned();
+ assert_eq!(iter.collect_tuple(), Some((1, 2)));
+
+ let v = [1];
+ let iter = v.iter().cloned();
+ assert_eq!(iter.collect_tuple::<(_, _)>(), None);
+
+ let v = [1, 2, 3];
+ let iter = v.iter().cloned();
+ assert_eq!(iter.collect_tuple::<(_, _)>(), None);
+}
--- /dev/null
+use itertools::Itertools;
+use itertools::EitherOrBoth::{Both, Left, Right};
+use itertools::free::zip_eq;
+use itertools::multizip;
+
+#[test]
+fn zip_longest_fused() {
+ let a = [Some(1), None, Some(3), Some(4)];
+ let b = [1, 2, 3];
+
+ let unfused = a.iter().batching(|it| *it.next().unwrap())
+ .zip_longest(b.iter().cloned());
+ itertools::assert_equal(unfused,
+ vec![Both(1, 1), Right(2), Right(3)]);
+}
+
+#[test]
+fn test_zip_longest_size_hint() {
+ let c = (1..10).cycle();
+ let v: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+ let v2 = &[10, 11, 12];
+
+ assert_eq!(c.zip_longest(v.iter()).size_hint(), (std::usize::MAX, None));
+
+ assert_eq!(v.iter().zip_longest(v2.iter()).size_hint(), (10, Some(10)));
+}
+
+#[test]
+fn test_double_ended_zip_longest() {
+ let xs = [1, 2, 3, 4, 5, 6];
+ let ys = [1, 2, 3, 7];
+ let a = xs.iter().copied();
+ let b = ys.iter().copied();
+ let mut it = a.zip_longest(b);
+ assert_eq!(it.next(), Some(Both(1, 1)));
+ assert_eq!(it.next(), Some(Both(2, 2)));
+ assert_eq!(it.next_back(), Some(Left(6)));
+ assert_eq!(it.next_back(), Some(Left(5)));
+ assert_eq!(it.next_back(), Some(Both(4, 7)));
+ assert_eq!(it.next(), Some(Both(3, 3)));
+ assert_eq!(it.next(), None);
+}
+
+#[test]
+fn test_double_ended_zip() {
+ let xs = [1, 2, 3, 4, 5, 6];
+ let ys = [1, 2, 3, 7];
+ let a = xs.iter().copied();
+ let b = ys.iter().copied();
+ let mut it = multizip((a, b));
+ assert_eq!(it.next_back(), Some((4, 7)));
+ assert_eq!(it.next_back(), Some((3, 3)));
+ assert_eq!(it.next_back(), Some((2, 2)));
+ assert_eq!(it.next_back(), Some((1, 1)));
+ assert_eq!(it.next_back(), None);
+}
+
+
+#[should_panic]
+#[test]
+fn zip_eq_panic1()
+{
+ let a = [1, 2];
+ let b = [1, 2, 3];
+
+ zip_eq(&a, &b).count();
+}
+
+#[should_panic]
+#[test]
+fn zip_eq_panic2()
+{
+ let a: [i32; 0] = [];
+ let b = [1, 2, 3];
+
+ zip_eq(&a, &b).count();
+}
projects / platform / upstream / rust-itertools.git / commitdiff