/*
* Copyright © 2018 Google, Inc.
+ * Copyright © 2019 Facebook, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
+ * Facebook Author(s): Behdad Esfahbod
*/
#ifndef HB_ITER_HH
#define HB_ITER_HH
#include "hb.hh"
-#include "hb-null.hh"
+#include "hb-algs.hh"
+#include "hb-meta.hh"
/* Unified iterator object.
* copied by value. If the collection / object being iterated on
* is writable, then the iterator returns lvalues, otherwise it
* returns rvalues.
+ *
+ * TODO Document more.
+ *
+ * If iterator implementation implements operator!=, then can be
+ * used in range-based for loop. That comes free if the iterator
+ * is random-access. Otherwise, the range-based for loop incurs
+ * one traversal to find end(), which can be avoided if written
+ * as a while-style for loop, or if iterator implements a faster
+ * __end__() method.
+ * TODO When opting in for C++17, address this by changing return
+ * type of .end()?
+ */
+
+/*
+ * Base classes for iterators.
*/
/* Base class for all iterators. */
-template <typename Iter, typename Item = typename Iter::__item_type__>
+template <typename iter_t, typename Item = typename iter_t::__item_t__>
struct hb_iter_t
{
- typedef Iter iter_t;
- typedef iter_t const_iter_t;
typedef Item item_t;
- static constexpr unsigned item_size = hb_static_size (Item);
+ constexpr unsigned get_item_size () const { return hb_static_size (Item); }
+ static constexpr bool is_iterator = true;
+ static constexpr bool is_random_access_iterator = false;
+ static constexpr bool is_sorted_iterator = false;
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
- iter_t* thiz () { return static_cast< iter_t *> (this); }
+ iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
- /* Operators. */
- operator iter_t () { return iter(); }
- explicit_operator bool () const { return more (); }
- item_t& operator * () const { return item (); }
- item_t& operator [] (signed i) const { return item_at ((unsigned) i); }
- iter_t& operator += (unsigned count) { forward (count); return *thiz(); }
- iter_t& operator ++ () { next (); return *thiz(); }
- iter_t& operator -= (unsigned count) { rewind (count); return *thiz(); }
- iter_t& operator -- () { prev (); return *thiz(); }
- iter_t operator + (unsigned count) { iter_t c (*thiz()); c += count; return c; }
- iter_t operator ++ (int) { iter_t c (*thiz()); ++*thiz(); return c; }
- iter_t operator - (unsigned count) { iter_t c (*thiz()); c -= count; return c; }
- iter_t operator -- (int) { iter_t c (*thiz()); --*thiz(); return c; }
+ /* TODO:
+ * Port operators below to use hb_enable_if to sniff which method implements
+ * an operator and use it, and remove hb_iter_fallback_mixin_t completely. */
- /* Methods. */
+ /* Operators. */
iter_t iter () const { return *thiz(); }
- const_iter_t const_iter () const { return iter (); }
- item_t& item () const { return thiz()->__item__ (); }
- item_t& item_at (unsigned i) const { return thiz()->__item_at__ (i); }
- bool more () const { return thiz()->__more__ (); }
+ iter_t operator + () const { return *thiz(); }
+ iter_t begin () const { return *thiz(); }
+ iter_t end () const { return thiz()->__end__ (); }
+ explicit operator bool () const { return thiz()->__more__ (); }
unsigned len () const { return thiz()->__len__ (); }
- void next () { thiz()->__next__ (); }
- void forward (unsigned n) { thiz()->__forward__ (n); }
- void prev () { thiz()->__prev__ (); }
- void rewind (unsigned n) { thiz()->__rewind__ (n); }
- bool random_access () const { return thiz()->__random_access__ (); }
+ /* The following can only be enabled if item_t is reference type. Otherwise
+ * it will be returning pointer to temporary rvalue.
+ * TODO Use a wrapper return type to fix for non-reference type. */
+ template <typename T = item_t,
+ hb_enable_if (hb_is_reference (T))>
+ hb_remove_reference<item_t>* operator -> () const { return hb_addressof (**thiz()); }
+ item_t operator * () const { return thiz()->__item__ (); }
+ item_t operator * () { return thiz()->__item__ (); }
+ item_t operator [] (unsigned i) const { return thiz()->__item_at__ (i); }
+ item_t operator [] (unsigned i) { return thiz()->__item_at__ (i); }
+ iter_t& operator += (unsigned count) & { thiz()->__forward__ (count); return *thiz(); }
+ iter_t operator += (unsigned count) && { thiz()->__forward__ (count); return *thiz(); }
+ iter_t& operator ++ () & { thiz()->__next__ (); return *thiz(); }
+ iter_t operator ++ () && { thiz()->__next__ (); return *thiz(); }
+ iter_t& operator -= (unsigned count) & { thiz()->__rewind__ (count); return *thiz(); }
+ iter_t operator -= (unsigned count) && { thiz()->__rewind__ (count); return *thiz(); }
+ iter_t& operator -- () & { thiz()->__prev__ (); return *thiz(); }
+ iter_t operator -- () && { thiz()->__prev__ (); return *thiz(); }
+ iter_t operator + (unsigned count) const { auto c = thiz()->iter (); c += count; return c; }
+ friend iter_t operator + (unsigned count, const iter_t &it) { return it + count; }
+ iter_t operator ++ (int) { iter_t c (*thiz()); ++*thiz(); return c; }
+ iter_t operator - (unsigned count) const { auto c = thiz()->iter (); c -= count; return c; }
+ iter_t operator -- (int) { iter_t c (*thiz()); --*thiz(); return c; }
+ template <typename T>
+ iter_t& operator >> (T &v) & { v = **thiz(); ++*thiz(); return *thiz(); }
+ template <typename T>
+ iter_t operator >> (T &v) && { v = **thiz(); ++*thiz(); return *thiz(); }
+ template <typename T>
+ iter_t& operator << (const T v) & { **thiz() = v; ++*thiz(); return *thiz(); }
+ template <typename T>
+ iter_t operator << (const T v) && { **thiz() = v; ++*thiz(); return *thiz(); }
protected:
- hb_iter_t () {}
- hb_iter_t (const hb_iter_t &o HB_UNUSED) {}
- void operator = (const hb_iter_t &o HB_UNUSED) {}
+ hb_iter_t () = default;
+ hb_iter_t (const hb_iter_t &o HB_UNUSED) = default;
+ hb_iter_t (hb_iter_t &&o HB_UNUSED) = default;
+ hb_iter_t& operator = (const hb_iter_t &o HB_UNUSED) = default;
+ hb_iter_t& operator = (hb_iter_t &&o HB_UNUSED) = default;
};
-/* Base class for sorted iterators. Does not enforce anything.
- * Just for class taxonomy and requirements. */
-template <typename Iter, typename Item = typename Iter::__item_type__>
-struct hb_sorted_iter_t : hb_iter_t<Iter, Item>
+#define HB_ITER_USING(Name) \
+ using item_t = typename Name::item_t; \
+ using Name::begin; \
+ using Name::end; \
+ using Name::get_item_size; \
+ using Name::is_iterator; \
+ using Name::iter; \
+ using Name::operator bool; \
+ using Name::len; \
+ using Name::operator ->; \
+ using Name::operator *; \
+ using Name::operator []; \
+ using Name::operator +=; \
+ using Name::operator ++; \
+ using Name::operator -=; \
+ using Name::operator --; \
+ using Name::operator +; \
+ using Name::operator -; \
+ using Name::operator >>; \
+ using Name::operator <<; \
+ static_assert (true, "")
+
+/* Returns iterator / item type of a type. */
+template <typename Iterable>
+using hb_iter_type = decltype (hb_deref (hb_declval (Iterable)).iter ());
+template <typename Iterable>
+using hb_item_type = decltype (*hb_deref (hb_declval (Iterable)).iter ());
+
+
+template <typename> struct hb_array_t;
+template <typename> struct hb_sorted_array_t;
+
+struct
{
- protected:
- hb_sorted_iter_t () {}
- hb_sorted_iter_t (const hb_sorted_iter_t &o) : hb_iter_t<Iter, Item> (o) {}
- void operator = (const hb_sorted_iter_t &o HB_UNUSED) {}
-};
+ template <typename T> hb_iter_type<T>
+ operator () (T&& c) const
+ { return hb_deref (hb_forward<T> (c)).iter (); }
+
+ /* Specialization for C arrays. */
+
+ template <typename Type> inline hb_array_t<Type>
+ operator () (Type *array, unsigned int length) const
+ { return hb_array_t<Type> (array, length); }
+
+ template <typename Type, unsigned int length> hb_array_t<Type>
+ operator () (Type (&array)[length]) const
+ { return hb_array_t<Type> (array, length); }
+
+}
+HB_FUNCOBJ (hb_iter);
+struct
+{
+ template <typename T> unsigned
+ operator () (T&& c) const
+ { return c.len (); }
+
+}
+HB_FUNCOBJ (hb_len);
/* Mixin to fill in what the subclass doesn't provide. */
-template <typename iter_t, typename item_t = typename iter_t::__item_type__>
-struct hb_iter_mixin_t
+template <typename iter_t, typename item_t = typename iter_t::__item_t__>
+struct hb_iter_fallback_mixin_t
{
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
- iter_t* thiz () { return static_cast< iter_t *> (this); }
+ iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
/* Access: Implement __item__(), or __item_at__() if random-access. */
- item_t& __item__ () const { return thiz()->item_at (0); }
- item_t& __item_at__ (unsigned i) const { return *(thiz() + i); }
+ item_t __item__ () const { return (*thiz())[0]; }
+ item_t __item_at__ (unsigned i) const { return *(*thiz() + i); }
/* Termination: Implement __more__(), or __len__() if random-access. */
- bool __more__ () const { return thiz()->__len__ (); }
+ bool __more__ () const { return bool (thiz()->len ()); }
unsigned __len__ () const
- { iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; }; return l; }
+ { iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; } return l; }
/* Advancing: Implement __next__(), or __forward__() if random-access. */
- void __next__ () { thiz()->forward (1); }
- void __forward__ (unsigned n) { while (n--) thiz()->next (); }
+ void __next__ () { *thiz() += 1; }
+ void __forward__ (unsigned n) { while (*thiz() && n--) ++*thiz(); }
/* Rewinding: Implement __prev__() or __rewind__() if bidirectional. */
- void __prev__ () { thiz()->rewind (1); }
- void __rewind__ (unsigned n) { while (n--) thiz()->prev (); }
+ void __prev__ () { *thiz() -= 1; }
+ void __rewind__ (unsigned n) { while (*thiz() && n--) --*thiz(); }
+
+ /* Range-based for: Implement __end__() if can be done faster,
+ * and operator!=. */
+ iter_t __end__ () const
+ {
+ if (thiz()->is_random_access_iterator)
+ return *thiz() + thiz()->len ();
+ /* Above expression loops twice. Following loops once. */
+ auto it = *thiz();
+ while (it) ++it;
+ return it;
+ }
+
+ protected:
+ hb_iter_fallback_mixin_t () = default;
+ hb_iter_fallback_mixin_t (const hb_iter_fallback_mixin_t &o HB_UNUSED) = default;
+ hb_iter_fallback_mixin_t (hb_iter_fallback_mixin_t &&o HB_UNUSED) = default;
+ hb_iter_fallback_mixin_t& operator = (const hb_iter_fallback_mixin_t &o HB_UNUSED) = default;
+ hb_iter_fallback_mixin_t& operator = (hb_iter_fallback_mixin_t &&o HB_UNUSED) = default;
+};
+
+template <typename iter_t, typename item_t = typename iter_t::__item_t__>
+struct hb_iter_with_fallback_t :
+ hb_iter_t<iter_t, item_t>,
+ hb_iter_fallback_mixin_t<iter_t, item_t>
+{
+ protected:
+ hb_iter_with_fallback_t () = default;
+ hb_iter_with_fallback_t (const hb_iter_with_fallback_t &o HB_UNUSED) = default;
+ hb_iter_with_fallback_t (hb_iter_with_fallback_t &&o HB_UNUSED) = default;
+ hb_iter_with_fallback_t& operator = (const hb_iter_with_fallback_t &o HB_UNUSED) = default;
+ hb_iter_with_fallback_t& operator = (hb_iter_with_fallback_t &&o HB_UNUSED) = default;
+};
+
+/*
+ * Meta-programming predicates.
+ */
+
+/* hb_is_iterator() / hb_is_iterator_of() */
+
+template<typename Iter, typename Item>
+struct hb_is_iterator_of
+{
+ template <typename Item2 = Item>
+ static hb_true_type impl (hb_priority<2>, hb_iter_t<Iter, hb_type_identity<Item2>> *);
+ static hb_false_type impl (hb_priority<0>, const void *);
+
+ public:
+ static constexpr bool value = decltype (impl (hb_prioritize, hb_declval (Iter*)))::value;
+};
+#define hb_is_iterator_of(Iter, Item) hb_is_iterator_of<Iter, Item>::value
+#define hb_is_iterator(Iter) hb_is_iterator_of (Iter, typename Iter::item_t)
+
+/* hb_is_iterable() */
+
+template <typename T>
+struct hb_is_iterable
+{
+ private:
+
+ template <typename U>
+ static auto impl (hb_priority<1>) -> decltype (hb_declval (U).iter (), hb_true_type ());
+
+ template <typename>
+ static hb_false_type impl (hb_priority<0>);
+
+ public:
+ static constexpr bool value = decltype (impl<T> (hb_prioritize))::value;
+};
+#define hb_is_iterable(Iterable) hb_is_iterable<Iterable>::value
+
+/* hb_is_source_of() / hb_is_sink_of() */
+
+template<typename Iter, typename Item>
+struct hb_is_source_of
+{
+ private:
+ template <typename Iter2 = Iter,
+ hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<hb_add_const<Item>>))>
+ static hb_true_type impl (hb_priority<2>);
+ template <typename Iter2 = Iter>
+ static auto impl (hb_priority<1>) -> decltype (hb_declval (Iter2) >> hb_declval (Item &), hb_true_type ());
+ static hb_false_type impl (hb_priority<0>);
+
+ public:
+ static constexpr bool value = decltype (impl (hb_prioritize))::value;
+};
+#define hb_is_source_of(Iter, Item) hb_is_source_of<Iter, Item>::value
+
+template<typename Iter, typename Item>
+struct hb_is_sink_of
+{
+ private:
+ template <typename Iter2 = Iter,
+ hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<Item>))>
+ static hb_true_type impl (hb_priority<2>);
+ template <typename Iter2 = Iter>
+ static auto impl (hb_priority<1>) -> decltype (hb_declval (Iter2) << hb_declval (Item), hb_true_type ());
+ static hb_false_type impl (hb_priority<0>);
+
+ public:
+ static constexpr bool value = decltype (impl (hb_prioritize))::value;
+};
+#define hb_is_sink_of(Iter, Item) hb_is_sink_of<Iter, Item>::value
+
+/* This is commonly used, so define: */
+#define hb_is_sorted_source_of(Iter, Item) \
+ (hb_is_source_of(Iter, Item) && Iter::is_sorted_iterator)
+
+
+/* Range-based 'for' for iterables. */
+
+template <typename Iterable,
+ hb_requires (hb_is_iterable (Iterable))>
+static inline auto begin (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).begin ())
+
+template <typename Iterable,
+ hb_requires (hb_is_iterable (Iterable))>
+static inline auto end (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).end ())
+
+/* begin()/end() are NOT looked up non-ADL. So each namespace must declare them.
+ * Do it for namespace OT. */
+namespace OT {
+
+template <typename Iterable,
+ hb_requires (hb_is_iterable (Iterable))>
+static inline auto begin (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).begin ())
+
+template <typename Iterable,
+ hb_requires (hb_is_iterable (Iterable))>
+static inline auto end (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).end ())
+
+}
+
+
+/*
+ * Adaptors, combiners, etc.
+ */
+
+template <typename Lhs, typename Rhs,
+ hb_requires (hb_is_iterator (Lhs))>
+static inline auto
+operator | (Lhs&& lhs, Rhs&& rhs) HB_AUTO_RETURN (hb_forward<Rhs> (rhs) (hb_forward<Lhs> (lhs)))
+
+/* hb_map(), hb_filter(), hb_reduce() */
+
+enum class hb_function_sortedness_t {
+ NOT_SORTED,
+ RETAINS_SORTING,
+ SORTED,
+};
+
+template <typename Iter, typename Proj, hb_function_sortedness_t Sorted,
+ hb_requires (hb_is_iterator (Iter))>
+struct hb_map_iter_t :
+ hb_iter_t<hb_map_iter_t<Iter, Proj, Sorted>,
+ decltype (hb_get (hb_declval (Proj), *hb_declval (Iter)))>
+{
+ hb_map_iter_t (const Iter& it, Proj f_) : it (it), f (f_) {}
+
+ typedef decltype (hb_get (hb_declval (Proj), *hb_declval (Iter))) __item_t__;
+ static constexpr bool is_random_access_iterator = Iter::is_random_access_iterator;
+ static constexpr bool is_sorted_iterator =
+ Sorted == hb_function_sortedness_t::SORTED ? true :
+ Sorted == hb_function_sortedness_t::RETAINS_SORTING ? Iter::is_sorted_iterator :
+ false;
+ __item_t__ __item__ () const { return hb_get (f.get (), *it); }
+ __item_t__ __item_at__ (unsigned i) const { return hb_get (f.get (), it[i]); }
+ bool __more__ () const { return bool (it); }
+ unsigned __len__ () const { return it.len (); }
+ void __next__ () { ++it; }
+ void __forward__ (unsigned n) { it += n; }
+ void __prev__ () { --it; }
+ void __rewind__ (unsigned n) { it -= n; }
+ hb_map_iter_t __end__ () const { return hb_map_iter_t (it.end (), f); }
+ bool operator != (const hb_map_iter_t& o) const
+ { return it != o.it; }
+
+ private:
+ Iter it;
+ hb_reference_wrapper<Proj> f;
+};
+
+template <typename Proj, hb_function_sortedness_t Sorted>
+struct hb_map_iter_factory_t
+{
+ hb_map_iter_factory_t (Proj f) : f (f) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ hb_map_iter_t<Iter, Proj, Sorted>
+ operator () (Iter it)
+ { return hb_map_iter_t<Iter, Proj, Sorted> (it, f); }
+
+ private:
+ Proj f;
+};
+struct
+{
+ template <typename Proj>
+ hb_map_iter_factory_t<Proj, hb_function_sortedness_t::NOT_SORTED>
+ operator () (Proj&& f) const
+ { return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::NOT_SORTED> (f); }
+}
+HB_FUNCOBJ (hb_map);
+struct
+{
+ template <typename Proj>
+ hb_map_iter_factory_t<Proj, hb_function_sortedness_t::RETAINS_SORTING>
+ operator () (Proj&& f) const
+ { return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::RETAINS_SORTING> (f); }
+}
+HB_FUNCOBJ (hb_map_retains_sorting);
+struct
+{
+ template <typename Proj>
+ hb_map_iter_factory_t<Proj, hb_function_sortedness_t::SORTED>
+ operator () (Proj&& f) const
+ { return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::SORTED> (f); }
+}
+HB_FUNCOBJ (hb_map_sorted);
+
+template <typename Iter, typename Pred, typename Proj,
+ hb_requires (hb_is_iterator (Iter))>
+struct hb_filter_iter_t :
+ hb_iter_with_fallback_t<hb_filter_iter_t<Iter, Pred, Proj>,
+ typename Iter::item_t>
+{
+ hb_filter_iter_t (const Iter& it_, Pred p_, Proj f_) : it (it_), p (p_), f (f_)
+ { while (it && !hb_has (p.get (), hb_get (f.get (), *it))) ++it; }
+
+ typedef typename Iter::item_t __item_t__;
+ static constexpr bool is_sorted_iterator = Iter::is_sorted_iterator;
+ __item_t__ __item__ () const { return *it; }
+ bool __more__ () const { return bool (it); }
+ void __next__ () { do ++it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); }
+ void __prev__ () { do --it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); }
+ hb_filter_iter_t __end__ () const { return hb_filter_iter_t (it.end (), p, f); }
+ bool operator != (const hb_filter_iter_t& o) const
+ { return it != o.it; }
+
+ private:
+ Iter it;
+ hb_reference_wrapper<Pred> p;
+ hb_reference_wrapper<Proj> f;
+};
+template <typename Pred, typename Proj>
+struct hb_filter_iter_factory_t
+{
+ hb_filter_iter_factory_t (Pred p, Proj f) : p (p), f (f) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ hb_filter_iter_t<Iter, Pred, Proj>
+ operator () (Iter it)
+ { return hb_filter_iter_t<Iter, Pred, Proj> (it, p, f); }
+
+ private:
+ Pred p;
+ Proj f;
+};
+struct
+{
+ template <typename Pred = decltype ((hb_identity)),
+ typename Proj = decltype ((hb_identity))>
+ hb_filter_iter_factory_t<Pred, Proj>
+ operator () (Pred&& p = hb_identity, Proj&& f = hb_identity) const
+ { return hb_filter_iter_factory_t<Pred, Proj> (p, f); }
+}
+HB_FUNCOBJ (hb_filter);
+
+template <typename Redu, typename InitT>
+struct hb_reduce_t
+{
+ hb_reduce_t (Redu r, InitT init_value) : r (r), init_value (init_value) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter)),
+ typename AccuT = hb_decay<decltype (hb_declval (Redu) (hb_declval (InitT), hb_declval (typename Iter::item_t)))>>
+ AccuT
+ operator () (Iter it)
+ {
+ AccuT value = init_value;
+ for (; it; ++it)
+ value = r (value, *it);
+ return value;
+ }
+
+ private:
+ Redu r;
+ InitT init_value;
+};
+struct
+{
+ template <typename Redu, typename InitT>
+ hb_reduce_t<Redu, InitT>
+ operator () (Redu&& r, InitT init_value) const
+ { return hb_reduce_t<Redu, InitT> (r, init_value); }
+}
+HB_FUNCOBJ (hb_reduce);
+
+
+/* hb_zip() */
- /* Random access: Return true if item_at(), len(), forward() are fast. */
- bool __random_access__ () const { return false; }
+template <typename A, typename B>
+struct hb_zip_iter_t :
+ hb_iter_t<hb_zip_iter_t<A, B>,
+ hb_pair_t<typename A::item_t, typename B::item_t>>
+{
+ hb_zip_iter_t () {}
+ hb_zip_iter_t (const A& a, const B& b) : a (a), b (b) {}
+
+ typedef hb_pair_t<typename A::item_t, typename B::item_t> __item_t__;
+ static constexpr bool is_random_access_iterator =
+ A::is_random_access_iterator &&
+ B::is_random_access_iterator;
+ /* Note. The following categorization is only valid if A is strictly sorted,
+ * ie. does NOT have duplicates. Previously I tried to categorize sortedness
+ * more granularly, see commits:
+ *
+ * 513762849a683914fc266a17ddf38f133cccf072
+ * 4d3cf2adb669c345cc43832d11689271995e160a
+ *
+ * However, that was not enough, since hb_sorted_array_t, hb_sorted_vector_t,
+ * SortedArrayOf, etc all needed to be updated to add more variants. At that
+ * point I saw it not worth the effort, and instead we now deem all sorted
+ * collections as essentially strictly-sorted for the purposes of zip.
+ *
+ * The above assumption is not as bad as it sounds. Our "sorted" comes with
+ * no guarantees. It's just a contract, put in place to help you remember,
+ * and think about, whether an iterator you receive is expected to be
+ * sorted or not. As such, it's not perfect by definition, and should not
+ * be treated so. The inaccuracy here just errs in the direction of being
+ * more permissive, so your code compiles instead of erring on the side of
+ * marking your zipped iterator unsorted in which case your code won't
+ * compile.
+ *
+ * This semantical limitation does NOT affect logic in any other place I
+ * know of as of this writing.
+ */
+ static constexpr bool is_sorted_iterator = A::is_sorted_iterator;
+
+ __item_t__ __item__ () const { return __item_t__ (*a, *b); }
+ __item_t__ __item_at__ (unsigned i) const { return __item_t__ (a[i], b[i]); }
+ bool __more__ () const { return bool (a) && bool (b); }
+ unsigned __len__ () const { return hb_min (a.len (), b.len ()); }
+ void __next__ () { ++a; ++b; }
+ void __forward__ (unsigned n) { a += n; b += n; }
+ void __prev__ () { --a; --b; }
+ void __rewind__ (unsigned n) { a -= n; b -= n; }
+ hb_zip_iter_t __end__ () const { return hb_zip_iter_t (a.end (), b.end ()); }
+ /* Note, we should stop if ANY of the iters reaches end. As such two compare
+ * unequal if both items are unequal, NOT if either is unequal. */
+ bool operator != (const hb_zip_iter_t& o) const
+ { return a != o.a && b != o.b; }
+
+ private:
+ A a;
+ B b;
+};
+struct
+{ HB_PARTIALIZE(2);
+ template <typename A, typename B,
+ hb_requires (hb_is_iterable (A) && hb_is_iterable (B))>
+ hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>>
+ operator () (A&& a, B&& b) const
+ { return hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>> (hb_iter (a), hb_iter (b)); }
+}
+HB_FUNCOBJ (hb_zip);
+
+/* hb_apply() */
+
+template <typename Appl>
+struct hb_apply_t
+{
+ hb_apply_t (Appl a) : a (a) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ void operator () (Iter it)
+ {
+ for (; it; ++it)
+ (void) hb_invoke (a, *it);
+ }
+
+ private:
+ Appl a;
};
+struct
+{
+ template <typename Appl> hb_apply_t<Appl>
+ operator () (Appl&& a) const
+ { return hb_apply_t<Appl> (a); }
+ template <typename Appl> hb_apply_t<Appl&>
+ operator () (Appl *a) const
+ { return hb_apply_t<Appl&> (*a); }
+}
+HB_FUNCOBJ (hb_apply);
+
+/* hb_range()/hb_iota()/hb_repeat() */
+
+template <typename T, typename S>
+struct hb_range_iter_t :
+ hb_iter_t<hb_range_iter_t<T, S>, T>
+{
+ hb_range_iter_t (T start, T end_, S step) : v (start), end_ (end_for (start, end_, step)), step (step) {}
+
+ typedef T __item_t__;
+ static constexpr bool is_random_access_iterator = true;
+ static constexpr bool is_sorted_iterator = true;
+ __item_t__ __item__ () const { return hb_ridentity (v); }
+ __item_t__ __item_at__ (unsigned j) const { return v + j * step; }
+ bool __more__ () const { return v != end_; }
+ unsigned __len__ () const { return !step ? UINT_MAX : (end_ - v) / step; }
+ void __next__ () { v += step; }
+ void __forward__ (unsigned n) { v += n * step; }
+ void __prev__ () { v -= step; }
+ void __rewind__ (unsigned n) { v -= n * step; }
+ hb_range_iter_t __end__ () const { return hb_range_iter_t (end_, end_, step); }
+ bool operator != (const hb_range_iter_t& o) const
+ { return v != o.v; }
+
+ private:
+ static inline T end_for (T start, T end_, S step)
+ {
+ if (!step)
+ return end_;
+ auto res = (end_ - start) % step;
+ if (!res)
+ return end_;
+ end_ += step - res;
+ return end_;
+ }
+
+ private:
+ T v;
+ T end_;
+ S step;
+};
+struct
+{
+ template <typename T = unsigned> hb_range_iter_t<T, unsigned>
+ operator () (T end = (unsigned) -1) const
+ { return hb_range_iter_t<T, unsigned> (0, end, 1u); }
+
+ template <typename T, typename S = unsigned> hb_range_iter_t<T, S>
+ operator () (T start, T end, S step = 1u) const
+ { return hb_range_iter_t<T, S> (start, end, step); }
+}
+HB_FUNCOBJ (hb_range);
+
+template <typename T, typename S>
+struct hb_iota_iter_t :
+ hb_iter_with_fallback_t<hb_iota_iter_t<T, S>, T>
+{
+ hb_iota_iter_t (T start, S step) : v (start), step (step) {}
+
+ private:
+
+ template <typename S2 = S>
+ auto
+ inc (hb_type_identity<S2> s, hb_priority<1>)
+ -> hb_void_t<decltype (hb_invoke (hb_forward<S2> (s), hb_declval<T&> ()))>
+ { v = hb_invoke (hb_forward<S2> (s), v); }
+
+ void
+ inc (S s, hb_priority<0>)
+ { v += s; }
+
+ public:
+
+ typedef T __item_t__;
+ static constexpr bool is_random_access_iterator = true;
+ static constexpr bool is_sorted_iterator = true;
+ __item_t__ __item__ () const { return hb_ridentity (v); }
+ bool __more__ () const { return true; }
+ unsigned __len__ () const { return UINT_MAX; }
+ void __next__ () { inc (step, hb_prioritize); }
+ void __prev__ () { v -= step; }
+ hb_iota_iter_t __end__ () const { return *this; }
+ bool operator != (const hb_iota_iter_t& o) const { return true; }
+
+ private:
+ T v;
+ S step;
+};
+struct
+{
+ template <typename T = unsigned, typename S = unsigned> hb_iota_iter_t<T, S>
+ operator () (T start = 0u, S step = 1u) const
+ { return hb_iota_iter_t<T, S> (start, step); }
+}
+HB_FUNCOBJ (hb_iota);
-/* Functions operating on iterators or iteratables. */
+template <typename T>
+struct hb_repeat_iter_t :
+ hb_iter_t<hb_repeat_iter_t<T>, T>
+{
+ hb_repeat_iter_t (T value) : v (value) {}
+
+ typedef T __item_t__;
+ static constexpr bool is_random_access_iterator = true;
+ static constexpr bool is_sorted_iterator = true;
+ __item_t__ __item__ () const { return v; }
+ __item_t__ __item_at__ (unsigned j) const { return v; }
+ bool __more__ () const { return true; }
+ unsigned __len__ () const { return UINT_MAX; }
+ void __next__ () {}
+ void __forward__ (unsigned) {}
+ void __prev__ () {}
+ void __rewind__ (unsigned) {}
+ hb_repeat_iter_t __end__ () const { return *this; }
+ bool operator != (const hb_repeat_iter_t& o) const { return true; }
+
+ private:
+ T v;
+};
+struct
+{
+ template <typename T> hb_repeat_iter_t<T>
+ operator () (T value) const
+ { return hb_repeat_iter_t<T> (value); }
+}
+HB_FUNCOBJ (hb_repeat);
+
+/* hb_enumerate()/hb_take() */
+
+struct
+{
+ template <typename Iterable,
+ typename Index = unsigned,
+ hb_requires (hb_is_iterable (Iterable))>
+ auto operator () (Iterable&& it, Index start = 0u) const HB_AUTO_RETURN
+ ( hb_zip (hb_iota (start), it) )
+}
+HB_FUNCOBJ (hb_enumerate);
+
+struct
+{ HB_PARTIALIZE(2);
+ template <typename Iterable,
+ hb_requires (hb_is_iterable (Iterable))>
+ auto operator () (Iterable&& it, unsigned count) const HB_AUTO_RETURN
+ ( hb_zip (hb_range (count), it) | hb_map (hb_second) )
+
+ /* Specialization arrays. */
+
+ template <typename Type> inline hb_array_t<Type>
+ operator () (hb_array_t<Type> array, unsigned count) const
+ { return array.sub_array (0, count); }
+
+ template <typename Type> inline hb_sorted_array_t<Type>
+ operator () (hb_sorted_array_t<Type> array, unsigned count) const
+ { return array.sub_array (0, count); }
+}
+HB_FUNCOBJ (hb_take);
+
+struct
+{ HB_PARTIALIZE(2);
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ auto operator () (Iter it, unsigned count) const HB_AUTO_RETURN
+ (
+ + hb_iota (it, hb_add (count))
+ | hb_map (hb_take (count))
+ | hb_take ((hb_len (it) + count - 1) / count)
+ )
+}
+HB_FUNCOBJ (hb_chop);
+
+/* hb_sink() */
+
+template <typename Sink>
+struct hb_sink_t
+{
+ hb_sink_t (Sink s) : s (s) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ void operator () (Iter it)
+ {
+ for (; it; ++it)
+ s << *it;
+ }
+
+ private:
+ Sink s;
+};
+struct
+{
+ template <typename Sink> hb_sink_t<Sink>
+ operator () (Sink&& s) const
+ { return hb_sink_t<Sink> (s); }
+
+ template <typename Sink> hb_sink_t<Sink&>
+ operator () (Sink *s) const
+ { return hb_sink_t<Sink&> (*s); }
+}
+HB_FUNCOBJ (hb_sink);
+
+/* hb-drain: hb_sink to void / blackhole / /dev/null. */
+
+struct
+{
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ void operator () (Iter it) const
+ {
+ for (; it; ++it)
+ (void) *it;
+ }
+}
+HB_FUNCOBJ (hb_drain);
+
+/* hb_unzip(): unzip and sink to two sinks. */
+
+template <typename Sink1, typename Sink2>
+struct hb_unzip_t
+{
+ hb_unzip_t (Sink1 s1, Sink2 s2) : s1 (s1), s2 (s2) {}
+
+ template <typename Iter,
+ hb_requires (hb_is_iterator (Iter))>
+ void operator () (Iter it)
+ {
+ for (; it; ++it)
+ {
+ const auto &v = *it;
+ s1 << v.first;
+ s2 << v.second;
+ }
+ }
+
+ private:
+ Sink1 s1;
+ Sink2 s2;
+};
+struct
+{
+ template <typename Sink1, typename Sink2> hb_unzip_t<Sink1, Sink2>
+ operator () (Sink1&& s1, Sink2&& s2) const
+ { return hb_unzip_t<Sink1, Sink2> (s1, s2); }
+
+ template <typename Sink1, typename Sink2> hb_unzip_t<Sink1&, Sink2&>
+ operator () (Sink1 *s1, Sink2 *s2) const
+ { return hb_unzip_t<Sink1&, Sink2&> (*s1, *s2); }
+}
+HB_FUNCOBJ (hb_unzip);
+
+
+/* hb-all, hb-any, hb-none. */
+
+struct
+{
+ template <typename Iterable,
+ typename Pred = decltype ((hb_identity)),
+ typename Proj = decltype ((hb_identity)),
+ hb_requires (hb_is_iterable (Iterable))>
+ bool operator () (Iterable&& c,
+ Pred&& p = hb_identity,
+ Proj&& f = hb_identity) const
+ {
+ for (auto it = hb_iter (c); it; ++it)
+ if (!hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
+ return false;
+ return true;
+ }
+}
+HB_FUNCOBJ (hb_all);
+struct
+{
+ template <typename Iterable,
+ typename Pred = decltype ((hb_identity)),
+ typename Proj = decltype ((hb_identity)),
+ hb_requires (hb_is_iterable (Iterable))>
+ bool operator () (Iterable&& c,
+ Pred&& p = hb_identity,
+ Proj&& f = hb_identity) const
+ {
+ for (auto it = hb_iter (c); it; ++it)
+ if (hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
+ return true;
+ return false;
+ }
+}
+HB_FUNCOBJ (hb_any);
+struct
+{
+ template <typename Iterable,
+ typename Pred = decltype ((hb_identity)),
+ typename Proj = decltype ((hb_identity)),
+ hb_requires (hb_is_iterable (Iterable))>
+ bool operator () (Iterable&& c,
+ Pred&& p = hb_identity,
+ Proj&& f = hb_identity) const
+ {
+ for (auto it = hb_iter (c); it; ++it)
+ if (hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
+ return false;
+ return true;
+ }
+}
+HB_FUNCOBJ (hb_none);
+
+/*
+ * Algorithms operating on iterators.
+ */
-template <typename C, typename V> inline void
-hb_fill (const C& c, const V &v)
+template <typename C, typename V,
+ hb_requires (hb_is_iterable (C))>
+inline void
+hb_fill (C& c, const V &v)
{
- for (typename C::iter_t i (c); i; i++)
- hb_assign (*i, v);
+ for (auto i = hb_iter (c); i; i++)
+ *i = v;
}
-template <typename S, typename D> inline bool
-hb_copy (hb_iter_t<D> &id, hb_iter_t<S> &is)
+template <typename S, typename D>
+inline void
+hb_copy (S&& is, D&& id)
{
- for (; id && is; ++id, ++is)
- *id = *is;
- return !is;
+ hb_iter (is) | hb_sink (id);
}
projects / platform / upstream / harfbuzz.git / blobdiff