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-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___RANGES_ADJACENT_VIEW_H
11#define _LIBCPP___RANGES_ADJACENT_VIEW_H
12
13#include <__config>
14
15#include <__algorithm/min.h>
16#include <__compare/three_way_comparable.h>
17#include <__concepts/constructible.h>
18#include <__concepts/convertible_to.h>
19#include <__concepts/equality_comparable.h>
20#include <__cstddef/size_t.h>
21#include <__functional/invoke.h>
22#include <__functional/operations.h>
23#include <__iterator/concepts.h>
24#include <__iterator/incrementable_traits.h>
25#include <__iterator/iter_move.h>
26#include <__iterator/iter_swap.h>
27#include <__iterator/iterator_traits.h>
28#include <__iterator/next.h>
29#include <__iterator/prev.h>
30#include <__ranges/access.h>
31#include <__ranges/all.h>
32#include <__ranges/concepts.h>
33#include <__ranges/empty_view.h>
34#include <__ranges/enable_borrowed_range.h>
35#include <__ranges/range_adaptor.h>
36#include <__ranges/size.h>
37#include <__ranges/view_interface.h>
38#include <__tuple/tuple_transform.h>
39#include <__type_traits/common_type.h>
40#include <__type_traits/is_nothrow_constructible.h>
41#include <__type_traits/make_unsigned.h>
42#include <__type_traits/maybe_const.h>
43#include <__utility/declval.h>
44#include <__utility/forward.h>
45#include <__utility/integer_sequence.h>
46#include <__utility/move.h>
47#include <array>
48#include <tuple>
49
50#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
51# pragma GCC system_header
52#endif
53
54_LIBCPP_PUSH_MACROS
55#include <__undef_macros>
56
57_LIBCPP_BEGIN_NAMESPACE_STD
58
59#if _LIBCPP_STD_VER >= 23
60
61namespace ranges {
62
63template <forward_range _View, size_t _Np>
64 requires view<_View> && (_Np > 0)
65class adjacent_view : public view_interface<adjacent_view<_View, _Np>> {
66private:
67 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
68
69 template <bool>
70 class __iterator;
71
72 template <bool>
73 class __sentinel;
74
75 struct __as_sentinel {};
76
77public:
78 _LIBCPP_HIDE_FROM_ABI adjacent_view()
79 requires default_initializable<_View>
80 = default;
81
82 _LIBCPP_HIDE_FROM_ABI constexpr explicit adjacent_view(_View __base) : __base_(std::move(__base)) {}
83
84 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
85 requires copy_constructible<_View>
86 {
87 return __base_;
88 }
89 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
90
91 _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
92 requires(!__simple_view<_View>)
93 {
94 return __iterator<false>(ranges::begin(__base_), ranges::end(__base_));
95 }
96
97 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
98 requires range<const _View> // LWG4482 This is under-constrained.
99 {
100 return __iterator<true>(ranges::begin(__base_), ranges::end(__base_));
101 }
102
103 _LIBCPP_HIDE_FROM_ABI constexpr auto end()
104 requires(!__simple_view<_View>)
105 {
106 if constexpr (common_range<_View>) {
107 return __iterator<false>(__as_sentinel{}, ranges::begin(__base_), ranges::end(__base_));
108 } else {
109 return __sentinel<false>(ranges::end(__base_));
110 }
111 }
112
113 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
114 requires range<const _View> // LWG4482 This is under-constrained.
115 {
116 if constexpr (common_range<const _View>) {
117 return __iterator<true>(__as_sentinel{}, ranges::begin(__base_), ranges::end(__base_));
118 } else {
119 return __sentinel<true>(ranges::end(__base_));
120 }
121 }
122
123 _LIBCPP_HIDE_FROM_ABI constexpr auto size()
124 requires sized_range<_View>
125 {
126 using _ST = decltype(ranges::size(__base_));
127 using _CT = common_type_t<_ST, size_t>;
128 auto __sz = static_cast<_CT>(ranges::size(__base_));
129 __sz -= std::min<_CT>(__sz, _Np - 1);
130 return static_cast<_ST>(__sz);
131 }
132
133 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
134 requires sized_range<const _View>
135 {
136 using _ST = decltype(ranges::size(__base_));
137 using _CT = common_type_t<_ST, size_t>;
138 auto __sz = static_cast<_CT>(ranges::size(__base_));
139 __sz -= std::min<_CT>(__sz, _Np - 1);
140 return static_cast<_ST>(__sz);
141 }
142};
143
144struct __adjacent_view_iter_access {
145 template <class _Iter>
146 _LIBCPP_HIDE_FROM_ABI constexpr static auto& __get_current(_Iter& __it) noexcept {
147 return __it.__current_;
148 }
149};
150
151template <forward_range _View, size_t _Np>
152 requires view<_View> && (_Np > 0)
153template <bool _Const>
154class adjacent_view<_View, _Np>::__iterator {
155 friend __adjacent_view_iter_access;
156 friend adjacent_view;
157 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
158 array<iterator_t<_Base>, _Np> __current_ = array<iterator_t<_Base>, _Np>();
159
160 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(iterator_t<_Base> __first, sentinel_t<_Base> __last) {
161 __current_[0] = __first;
162 for (size_t __i = 1; __i < _Np; ++__i) {
163 __current_[__i] = ranges::next(__current_[__i - 1], 1, __last);
164 }
165 }
166
167 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__as_sentinel, iterator_t<_Base> __first, iterator_t<_Base> __last) {
168 if constexpr (!bidirectional_range<_Base>) {
169 __current_.fill(__last);
170 } else {
171 __current_[_Np - 1] = __last;
172 for (int __i = static_cast<int>(_Np) - 2; __i >= 0; --__i) {
173 __current_[__i] = ranges::prev(__current_[__i + 1], 1, __first);
174 }
175 }
176 }
177
178 template <class _Iter, size_t... _Is>
179 _LIBCPP_HIDE_FROM_ABI explicit constexpr __iterator(_Iter&& __i, index_sequence<_Is...>)
180 : __current_{std::move(__i.__current_[_Is])...} {}
181
182 static consteval auto __get_iterator_concept() {
183 if constexpr (random_access_range<_Base>)
184 return random_access_iterator_tag{};
185 else if constexpr (bidirectional_range<_Base>)
186 return bidirectional_iterator_tag{};
187 else
188 return forward_iterator_tag{};
189 }
190
191 template <class _Tp, size_t _Index>
192 using __always _LIBCPP_NODEBUG = _Tp;
193
194 template <class _Tp, size_t... _Is>
195 static auto __repeat_tuple_helper(index_sequence<_Is...>) -> tuple<__always<_Tp, _Is>...>;
196
197public:
198 using iterator_category = input_iterator_tag;
199 using iterator_concept = decltype(__get_iterator_concept());
200 using value_type = decltype(__repeat_tuple_helper<range_value_t<_Base>>(make_index_sequence<_Np>{}));
201 using difference_type = range_difference_t<_Base>;
202
203 _LIBCPP_HIDE_FROM_ABI __iterator() = default;
204 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
205 requires _Const && convertible_to<iterator_t<_View>, iterator_t<const _View>>
206 : __iterator(std::move(__i), make_index_sequence<_Np>{}) {}
207
208 _LIBCPP_HIDE_FROM_ABI constexpr auto operator*() const {
209 return std::__tuple_transform([](auto& __i) -> decltype(auto) { return *__i; }, __current_);
210 }
211
212 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
213 for (auto& __i : __current_) {
214 ++__i;
215 }
216 return *this;
217 }
218
219 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) {
220 auto __tmp = *this;
221 ++*this;
222 return __tmp;
223 }
224
225 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
226 requires bidirectional_range<_Base>
227 {
228 for (auto& __i : __current_) {
229 --__i;
230 }
231 return *this;
232 }
233
234 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
235 requires bidirectional_range<_Base>
236 {
237 auto __tmp = *this;
238 --*this;
239 return __tmp;
240 }
241
242 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __x)
243 requires random_access_range<_Base>
244 {
245 for (auto& __i : __current_) {
246 __i += __x;
247 }
248 return *this;
249 }
250
251 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __x)
252 requires random_access_range<_Base>
253 {
254 for (auto& __i : __current_) {
255 __i -= __x;
256 }
257 return *this;
258 }
259
260 _LIBCPP_HIDE_FROM_ABI constexpr auto operator[](difference_type __n) const
261 requires random_access_range<_Base>
262 {
263 return std::__tuple_transform([&](auto& __i) -> decltype(auto) { return __i[__n]; }, __current_);
264 }
265
266 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) {
267 return __x.__current_.back() == __y.__current_.back();
268 }
269
270 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
271 requires random_access_range<_Base>
272 {
273 return __x.__current_.back() < __y.__current_.back();
274 }
275
276 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
277 requires random_access_range<_Base>
278 {
279 return __y < __x;
280 }
281
282 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
283 requires random_access_range<_Base>
284 {
285 return !(__y < __x);
286 }
287
288 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
289 requires random_access_range<_Base>
290 {
291 return !(__x < __y);
292 }
293
294 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
295 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
296 {
297 return __x.__current_.back() <=> __y.__current_.back();
298 }
299
300 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(const __iterator& __i, difference_type __n)
301 requires random_access_range<_Base>
302 {
303 auto __r = __i;
304 __r += __n;
305 return __r;
306 }
307
308 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, const __iterator& __i)
309 requires random_access_range<_Base>
310 {
311 return __i + __n;
312 }
313
314 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(const __iterator& __i, difference_type __n)
315 requires random_access_range<_Base>
316 {
317 auto __r = __i;
318 __r -= __n;
319 return __r;
320 }
321
322 _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
323 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
324 {
325 return __x.__current_.back() - __y.__current_.back();
326 }
327
328 _LIBCPP_HIDE_FROM_ABI friend constexpr auto iter_move(const __iterator& __i) noexcept(
329 noexcept(ranges::iter_move(std::declval<const iterator_t<_Base>&>())) &&
330 is_nothrow_move_constructible_v<range_rvalue_reference_t<_Base>>) {
331 return std::__tuple_transform(ranges::iter_move, __i.__current_);
332 }
333
334 _LIBCPP_HIDE_FROM_ABI friend constexpr void iter_swap(const __iterator& __l, const __iterator& __r) noexcept(
335 noexcept(ranges::iter_swap(std::declval<iterator_t<_Base>>(), std::declval<iterator_t<_Base>>())))
336 requires indirectly_swappable<iterator_t<_Base>>
337 {
338 for (size_t __i = 0; __i < _Np; ++__i) {
339 ranges::iter_swap(__l.__current_[__i], __r.__current_[__i]);
340 }
341 }
342};
343
344template <forward_range _View, size_t _Np>
345 requires view<_View> && (_Np > 0)
346template <bool _Const>
347class adjacent_view<_View, _Np>::__sentinel {
348 friend adjacent_view;
349 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
350 sentinel_t<_Base> __end_ = sentinel_t<_Base>();
351
352 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) { __end_ = std::move(__end); }
353
354public:
355 _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
356
357 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i)
358 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
359 : __end_(std::move(__i.__end_)) {}
360
361 template <bool _OtherConst>
362 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
363 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
364 return __x.__current_.back() == __y.__end_;
365 }
366
367 template <bool _OtherConst>
368 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
369 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
370 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
371 return __x.__current_.back() - __y.__end_;
372 }
373
374 template <bool _OtherConst>
375 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
376 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
377 operator-(const __sentinel& __y, const __iterator<_OtherConst>& __x) {
378 return __y.__end_ - __x.__current_.back();
379 }
380};
381
382template <class _View, size_t _Np>
383constexpr bool enable_borrowed_range<adjacent_view<_View, _Np>> = enable_borrowed_range<_View>;
384
385namespace views {
386namespace __adjacent {
387
388template <size_t _Np>
389struct __fn : __range_adaptor_closure<__fn<_Np>> {
390 template <class _Range>
391 requires(_Np == 0 && forward_range<_Range &&>)
392 _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Range&&) noexcept {
393 return empty_view<tuple<>>{};
394 }
395
396 template <class _Ranges>
397 _LIBCPP_HIDE_FROM_ABI static constexpr auto operator()(_Ranges&& __range) noexcept(
398 noexcept(adjacent_view<views::all_t<_Ranges&&>, _Np>(std::forward<_Ranges>(__range))))
399 -> decltype(adjacent_view<views::all_t<_Ranges&&>, _Np>(std::forward<_Ranges>(__range))) {
400 return adjacent_view<views::all_t<_Ranges&&>, _Np>(std::forward<_Ranges>(__range));
401 }
402};
403
404} // namespace __adjacent
405inline namespace __cpo {
406template <size_t _Np>
407inline constexpr auto adjacent = __adjacent::__fn<_Np>{};
408inline constexpr auto pairwise = adjacent<2>;
409} // namespace __cpo
410} // namespace views
411} // namespace ranges
412
413#endif // _LIBCPP_STD_VER >= 23
414
415_LIBCPP_END_NAMESPACE_STD
416
417_LIBCPP_POP_MACROS
418
419#endif // _LIBCPP___RANGES_ADJACENT_VIEW_H
420