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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___RANGES_CHUNK_BY_VIEW_H11#define _LIBCPP___RANGES_CHUNK_BY_VIEW_H12 13#include <__algorithm/ranges_adjacent_find.h>14#include <__assert>15#include <__concepts/constructible.h>16#include <__config>17#include <__functional/bind_back.h>18#include <__functional/invoke.h>19#include <__iterator/concepts.h>20#include <__iterator/default_sentinel.h>21#include <__iterator/iterator_traits.h>22#include <__iterator/next.h>23#include <__iterator/prev.h>24#include <__memory/addressof.h>25#include <__ranges/access.h>26#include <__ranges/all.h>27#include <__ranges/concepts.h>28#include <__ranges/movable_box.h>29#include <__ranges/non_propagating_cache.h>30#include <__ranges/range_adaptor.h>31#include <__ranges/reverse_view.h>32#include <__ranges/subrange.h>33#include <__ranges/view_interface.h>34#include <__type_traits/conditional.h>35#include <__type_traits/decay.h>36#include <__type_traits/is_nothrow_constructible.h>37#include <__type_traits/is_object.h>38#include <__utility/forward.h>39#include <__utility/in_place.h>40#include <__utility/move.h>41 42#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)43# pragma GCC system_header44#endif45 46_LIBCPP_PUSH_MACROS47#include <__undef_macros>48 49_LIBCPP_BEGIN_NAMESPACE_STD50 51#if _LIBCPP_STD_VER >= 2352 53namespace ranges {54 55template <forward_range _View, indirect_binary_predicate<iterator_t<_View>, iterator_t<_View>> _Pred>56 requires view<_View> && is_object_v<_Pred>57class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS chunk_by_view : public view_interface<chunk_by_view<_View, _Pred>> {58 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();59 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Pred> __pred_;60 61 // We cache the result of begin() to allow providing an amortized O(1).62 using _Cache _LIBCPP_NODEBUG = __non_propagating_cache<iterator_t<_View>>;63 _Cache __cached_begin_;64 65 class __iterator;66 67 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> __find_next(iterator_t<_View> __current) {68 // Note: this duplicates a check in `optional` but provides a better error message.69 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(70 __pred_.__has_value(), "Trying to call __find_next() on a chunk_by_view that does not have a valid predicate.");71 auto __reversed_pred = [this]<class _Tp, class _Up>(_Tp&& __x, _Up&& __y) -> bool {72 return !std::invoke(*__pred_, std::forward<_Tp>(__x), std::forward<_Up>(__y));73 };74 return ranges::next(75 ranges::adjacent_find(__current, ranges::end(__base_), __reversed_pred), 1, ranges::end(__base_));76 }77 78 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> __find_prev(iterator_t<_View> __current)79 requires bidirectional_range<_View>80 {81 // Attempting to decrement a begin iterator is a no-op (`__find_prev` would return the same argument given to it).82 _LIBCPP_ASSERT_PEDANTIC(__current != ranges::begin(__base_), "Trying to call __find_prev() on a begin iterator.");83 // Note: this duplicates a check in `optional` but provides a better error message.84 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(85 __pred_.__has_value(), "Trying to call __find_prev() on a chunk_by_view that does not have a valid predicate.");86 87 auto __first = ranges::begin(__base_);88 reverse_view __reversed{subrange{__first, __current}};89 auto __reversed_pred = [this]<class _Tp, class _Up>(_Tp&& __x, _Up&& __y) -> bool {90 return !std::invoke(*__pred_, std::forward<_Up>(__y), std::forward<_Tp>(__x));91 };92 return ranges::prev(ranges::adjacent_find(__reversed, __reversed_pred).base(), 1, std::move(__first));93 }94 95public:96 _LIBCPP_HIDE_FROM_ABI chunk_by_view()97 requires default_initializable<_View> && default_initializable<_Pred>98 = default;99 100 _LIBCPP_HIDE_FROM_ABI constexpr explicit chunk_by_view(_View __base, _Pred __pred)101 : __base_(std::move(__base)), __pred_(in_place, std::move(__pred)) {}102 103 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&104 requires copy_constructible<_View>105 {106 return __base_;107 }108 109 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }110 111 _LIBCPP_HIDE_FROM_ABI constexpr const _Pred& pred() const { return *__pred_; }112 113 _LIBCPP_HIDE_FROM_ABI constexpr __iterator begin() {114 // Note: this duplicates a check in `optional` but provides a better error message.115 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(116 __pred_.__has_value(), "Trying to call begin() on a chunk_by_view that does not have a valid predicate.");117 118 auto __first = ranges::begin(__base_);119 if (!__cached_begin_.__has_value()) {120 __cached_begin_.__emplace(__find_next(__first));121 }122 return {*this, std::move(__first), *__cached_begin_};123 }124 125 _LIBCPP_HIDE_FROM_ABI constexpr auto end() {126 if constexpr (common_range<_View>) {127 return __iterator{*this, ranges::end(__base_), ranges::end(__base_)};128 } else {129 return default_sentinel;130 }131 }132};133 134template <class _Range, class _Pred>135chunk_by_view(_Range&&, _Pred) -> chunk_by_view<views::all_t<_Range>, _Pred>;136 137template <forward_range _View, indirect_binary_predicate<iterator_t<_View>, iterator_t<_View>> _Pred>138 requires view<_View> && is_object_v<_Pred>139class chunk_by_view<_View, _Pred>::__iterator {140 friend chunk_by_view;141 142 chunk_by_view* __parent_ = nullptr;143 _LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __current_ = iterator_t<_View>();144 _LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __next_ = iterator_t<_View>();145 146 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(147 chunk_by_view& __parent, iterator_t<_View> __current, iterator_t<_View> __next)148 : __parent_(std::addressof(__parent)), __current_(__current), __next_(__next) {}149 150public:151 using value_type = subrange<iterator_t<_View>>;152 using difference_type = range_difference_t<_View>;153 using iterator_category = input_iterator_tag;154 using iterator_concept = conditional_t<bidirectional_range<_View>, bidirectional_iterator_tag, forward_iterator_tag>;155 156 _LIBCPP_HIDE_FROM_ABI __iterator() = default;157 158 _LIBCPP_HIDE_FROM_ABI constexpr value_type operator*() const {159 // If the iterator is at end, this would return an empty range which can be checked by the calling code and doesn't160 // necessarily lead to a bad access.161 _LIBCPP_ASSERT_PEDANTIC(__current_ != __next_, "Trying to dereference past-the-end chunk_by_view iterator.");162 return {__current_, __next_};163 }164 165 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {166 // Attempting to increment an end iterator is a no-op (`__find_next` would return the same argument given to it).167 _LIBCPP_ASSERT_PEDANTIC(__current_ != __next_, "Trying to increment past end chunk_by_view iterator.");168 __current_ = __next_;169 __next_ = __parent_->__find_next(__current_);170 return *this;171 }172 173 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) {174 auto __tmp = *this;175 ++*this;176 return __tmp;177 }178 179 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()180 requires bidirectional_range<_View>181 {182 __next_ = __current_;183 __current_ = __parent_->__find_prev(__next_);184 return *this;185 }186 187 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)188 requires bidirectional_range<_View>189 {190 auto __tmp = *this;191 --*this;192 return __tmp;193 }194 195 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) {196 return __x.__current_ == __y.__current_;197 }198 199 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, default_sentinel_t) {200 return __x.__current_ == __x.__next_;201 }202};203 204namespace views {205namespace __chunk_by {206struct __fn {207 template <class _Range, class _Pred>208 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const209 noexcept(noexcept(/**/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))))210 -> decltype(/*--*/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) {211 return /*-------------*/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred));212 }213 214 template <class _Pred>215 requires constructible_from<decay_t<_Pred>, _Pred>216 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pred&& __pred) const217 noexcept(is_nothrow_constructible_v<decay_t<_Pred>, _Pred>) {218 return __pipeable(std::__bind_back(*this, std::forward<_Pred>(__pred)));219 }220};221} // namespace __chunk_by222 223inline namespace __cpo {224inline constexpr auto chunk_by = __chunk_by::__fn{};225} // namespace __cpo226} // namespace views227} // namespace ranges228 229#endif // _LIBCPP_STD_VER >= 23230 231_LIBCPP_END_NAMESPACE_STD232 233_LIBCPP_POP_MACROS234 235#endif // _LIBCPP___RANGES_CHUNK_BY_VIEW_H236