From 4db904b3bbdfa53d802ca14464f8e412a49ba455 Mon Sep 17 00:00:00 2001
From: Michael Kruse <llvm@meinersbur.de>
Date: Tue, 4 Dec 2018 21:38:55 +0000
Subject: [PATCH] Revert "[ADT] Add zip_longest iterators"

This reverts commit r348301.

Compilation fails on buildbots with older versions of gcc and msvc.

llvm-svn: 348303
---
 llvm/include/llvm/ADT/STLExtras.h   | 126 +-----------------------------------
 llvm/unittests/ADT/IteratorTest.cpp |  30 ---------
 2 files changed, 1 insertion(+), 155 deletions(-)

diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index dba7279..ba31392 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -508,11 +508,9 @@ make_early_inc_range(RangeT &&Range) {
                     EarlyIncIteratorT(std::end(std::forward<RangeT>(Range))));
 }
 
-// forward declarations required by zip_shortest/zip_first/zip_longest
+// forward declarations required by zip_shortest/zip_first
 template <typename R, typename UnaryPredicate>
 bool all_of(R &&range, UnaryPredicate P);
-template <typename R, typename UnaryPredicate>
-bool any_of(R &&range, UnaryPredicate P);
 
 template <size_t... I> struct index_sequence;
 
@@ -663,128 +661,6 @@ detail::zippy<detail::zip_first, T, U, Args...> zip_first(T &&t, U &&u,
       std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
 }
 
-namespace detail {
-template <typename Iter>
-static Iter next_or_end(const Iter &I, const Iter &End) {
-  if (I == End)
-    return End;
-  return std::next(I);
-}
-
-template <typename Iter>
-static auto deref_or_none(const Iter &I, const Iter &End)
-    -> llvm::Optional<typename std::remove_const<
-        typename std::remove_reference<decltype(*I)>::type>::type> {
-  if (I == End)
-    return None;
-  return *I;
-}
-
-template <typename... Iters> struct ZipLongestValueType {
-  using type = std::tuple<
-      llvm::Optional<typename std::remove_const<typename std::remove_reference<
-          decltype(*std::declval<Iters>())>::type>::type>...>;
-};
-
-template <typename... Iters>
-class zip_longest_iterator
-    : public iterator_facade_base<
-          zip_longest_iterator<Iters...>,
-          typename std::common_type<
-              std::forward_iterator_tag,
-              typename std::iterator_traits<Iters>::iterator_category...>::type,
-          typename ZipLongestValueType<Iters...>::type,
-          typename std::iterator_traits<typename std::tuple_element<
-              0, std::tuple<Iters...>>::type>::difference_type,
-          typename ZipLongestValueType<Iters...>::type *,
-          typename ZipLongestValueType<Iters...>::type> {
-public:
-  using value_type = typename ZipLongestValueType<Iters...>::type;
-
-private:
-  std::tuple<Iters...> iterators;
-  std::tuple<Iters...> end_iterators;
-
-  template <size_t... Ns>
-  bool test(const zip_longest_iterator<Iters...> &other,
-            index_sequence<Ns...>) const {
-    return llvm::any_of(
-        std::initializer_list<bool>{std::get<Ns>(this->iterators) !=
-                                    std::get<Ns>(other.iterators)...},
-        identity<bool>{});
-  }
-
-  template <size_t... Ns> value_type deref(index_sequence<Ns...>) const {
-    return value_type(
-        deref_or_none(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
-  }
-
-  template <size_t... Ns>
-  decltype(iterators) tup_inc(index_sequence<Ns...>) const {
-    return std::tuple<Iters...>(
-        next_or_end(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
-  }
-
-public:
-  zip_longest_iterator(std::pair<Iters &&, Iters &&>... ts)
-      : iterators(std::forward<Iters>(ts.first)...),
-        end_iterators(std::forward<Iters>(ts.second)...) {}
-
-  value_type operator*() { return deref(index_sequence_for<Iters...>{}); }
-
-  value_type operator*() const { return deref(index_sequence_for<Iters...>{}); }
-
-  zip_longest_iterator<Iters...> &operator++() {
-    iterators = tup_inc(index_sequence_for<Iters...>{});
-    return *this;
-  }
-
-  bool operator==(const zip_longest_iterator<Iters...> &other) const {
-    return !test(other, index_sequence_for<Iters...>{});
-  }
-};
-
-template <typename... Args> class zip_longest_range {
-public:
-  using iterator =
-      zip_longest_iterator<decltype(adl_begin(std::declval<Args>()))...>;
-  using iterator_category = typename iterator::iterator_category;
-  using value_type = typename iterator::value_type;
-  using difference_type = typename iterator::difference_type;
-  using pointer = typename iterator::pointer;
-  using reference = typename iterator::reference;
-
-private:
-  std::tuple<Args...> ts;
-
-  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) const {
-    return iterator(std::make_pair(adl_begin(std::get<Ns>(ts)),
-                                   adl_end(std::get<Ns>(ts)))...);
-  }
-
-  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) const {
-    return iterator(std::make_pair(adl_end(std::get<Ns>(ts)),
-                                   adl_end(std::get<Ns>(ts)))...);
-  }
-
-public:
-  zip_longest_range(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
-
-  iterator begin() const { return begin_impl(index_sequence_for<Args...>{}); }
-  iterator end() const { return end_impl(index_sequence_for<Args...>{}); }
-};
-} // namespace detail
-
-/// Iterate over two or more iterators at the same time. Iteration continues
-/// until all iterators reach the end. The llvm::Optional only contains a value
-/// if the iterator has not reached the end.
-template <typename T, typename U, typename... Args>
-detail::zip_longest_range<T, U, Args...> zip_longest(T &&t, U &&u,
-                                                     Args &&... args) {
-  return detail::zip_longest_range<T, U, Args...>(
-      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
-}
-
 /// Iterator wrapper that concatenates sequences together.
 ///
 /// This can concatenate different iterators, even with different types, into
diff --git a/llvm/unittests/ADT/IteratorTest.cpp b/llvm/unittests/ADT/IteratorTest.cpp
index f15ba8e..de0a671 100644
--- a/llvm/unittests/ADT/IteratorTest.cpp
+++ b/llvm/unittests/ADT/IteratorTest.cpp
@@ -328,36 +328,6 @@ TEST(ZipIteratorTest, ZipFirstBasic) {
   EXPECT_EQ(iters, 4u);
 }
 
-TEST(ZipIteratorTest, ZipLongestBasic) {
-  using namespace std;
-  const vector<unsigned> pi{3, 1, 4, 1, 5, 9};
-  const vector<StringRef> e{"2", "7", "1", "8"};
-
-  {
-    // Check left range longer than right.
-    const vector<tuple<Optional<unsigned>, Optional<StringRef>>> expected{
-        {3, {"2"}}, {1, {"7"}}, {4, {"1"}}, {1, {"8"}}, {5, None}, {9, None}};
-    size_t iters = 0;
-    for (auto tup : zip_longest(pi, e)) {
-      EXPECT_EQ(tup, expected[iters]);
-      iters += 1;
-    }
-    EXPECT_EQ(iters, expected.size());
-  }
-
-  {
-    // Check right range longer than left.
-    const vector<tuple<Optional<StringRef>, Optional<unsigned>>> expected{
-        {{"2"}, 3}, {{"7"}, 1}, {{"1"}, 4}, {{"8"}, 1}, {None, 5}, {None, 9}};
-    size_t iters = 0;
-    for (auto tup : zip_longest(e, pi)) {
-      EXPECT_EQ(tup, expected[iters]);
-      iters += 1;
-    }
-    EXPECT_EQ(iters, expected.size());
-  }
-}
-
 TEST(ZipIteratorTest, Mutability) {
   using namespace std;
   const SmallVector<unsigned, 4> pi{3, 1, 4, 1, 5, 9};
-- 
2.7.4