/* * Copyright © 2018 Google, Inc. * Copyright © 2019 Facebook, Inc. * * This is part of HarfBuzz, a text shaping library. * * Permission is hereby granted, without written agreement and without * license or royalty fees, to use, copy, modify, and distribute this * software and its documentation for any purpose, provided that the * above copyright notice and the following two paragraphs appear in * all copies of this software. * * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO * 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-algs.hh" #include "hb-meta.hh" /* Unified iterator object. * * The goal of this template is to make the same iterator interface * available to all types, and make it very easy and compact to use. * hb_iter_tator objects are small, light-weight, objects that can be * copied by value. If the collection / object being iterated on * is writable, then the iterator returns lvalues, otherwise it * returns rvalues. * * If iterator implementation implements operator!=, then it can be * used in range-based for loop. That already happens 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. */ /* * Base classes for iterators. */ /* Base class for all iterators. */ template <typename iter_t, typename Item = typename iter_t::__item_t__> struct hb_iter_t { typedef Item item_t; 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); } public: /* Operators. */ iter_t iter () const { return *thiz(); } 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__ (); } /* The following can only be enabled if item_t is reference type. Otherwise * it will be returning pointer to temporary rvalue. */ template <typename T = item_t, hb_enable_if (std::is_reference<T>::value)> hb_remove_reference<item_t>* operator -> () const { return std::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 () = 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; }; #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 { template <typename T> hb_iter_type<T> operator () (T&& c) const { return hb_deref (std::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_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); } public: /* Access: Implement __item__(), or __item_at__() if random-access. */ 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 bool (thiz()->len ()); } unsigned __len__ () const { iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; } return l; } /* Advancing: Implement __next__(), or __forward__() if random-access. */ void __next__ () { *thiz() += 1; } void __forward__ (unsigned n) { while (*thiz() && n--) ++*thiz(); } /* Rewinding: Implement __prev__() or __rewind__() if bidirectional. */ 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) #define hb_is_sorted_iterator_of(Iter, Item) (hb_is_iterator_of<Iter, Item>::value && Iter::is_sorted_iterator) #define hb_is_sorted_iterator(Iter) hb_is_sorted_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<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 (std::forward<Rhs> (rhs) (std::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() */ 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_concat() */ template <typename A, typename B> struct hb_concat_iter_t : hb_iter_t<hb_concat_iter_t<A, B>, typename A::item_t> { hb_concat_iter_t () {} hb_concat_iter_t (A& a, B& b) : a (a), b (b) {} hb_concat_iter_t (const A& a, const B& b) : a (a), b (b) {} typedef typename A::item_t __item_t__; static constexpr bool is_random_access_iterator = A::is_random_access_iterator && B::is_random_access_iterator; static constexpr bool is_sorted_iterator = false; __item_t__ __item__ () const { if (!a) return *b; return *a; } __item_t__ __item_at__ (unsigned i) const { unsigned a_len = a.len (); if (i < a_len) return a[i]; return b[i - a_len]; } bool __more__ () const { return bool (a) || bool (b); } unsigned __len__ () const { return a.len () + b.len (); } void __next__ () { if (a) ++a; else ++b; } void __forward__ (unsigned n) { if (!n) return; if (!is_random_access_iterator) { while (n-- && *this) { (*this)++; } return; } unsigned a_len = a.len (); if (n > a_len) { n -= a_len; a.__forward__ (a_len); b.__forward__ (n); } else { a.__forward__ (n); } } hb_concat_iter_t __end__ () const { return hb_concat_iter_t (a.end (), b.end ()); } bool operator != (const hb_concat_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_concat_iter_t<hb_iter_type<A>, hb_iter_type<B>> operator () (A&& a, B&& b) const { return hb_concat_iter_t<hb_iter_type<A>, hb_iter_type<B>> (hb_iter (a), hb_iter (b)); } } HB_FUNCOBJ (hb_concat); /* 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 (std::forward<S2> (s), hb_declval<T&> ()))> { v = hb_invoke (std::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); 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 (std::forward<Pred> (p), hb_get (std::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 (std::forward<Pred> (p), hb_get (std::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 (std::forward<Pred> (p), hb_get (std::forward<Proj> (f), *it))) return false; return true; } } HB_FUNCOBJ (hb_none); /* * Algorithms operating on iterators. */ template <typename C, typename V, hb_requires (hb_is_iterable (C))> inline void hb_fill (C&& c, const V &v) { for (auto i = hb_iter (c); i; i++) *i = v; } template <typename S, typename D> inline void hb_copy (S&& is, D&& id) { hb_iter (is) | hb_sink (id); } #endif /* HB_ITER_HH */