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_TRANSFORM_VIEW_H
11#define _LIBCPP___RANGES_TRANSFORM_VIEW_H
12
13#include <__compare/three_way_comparable.h>
14#include <__concepts/constructible.h>
15#include <__concepts/convertible_to.h>
16#include <__concepts/derived_from.h>
17#include <__concepts/equality_comparable.h>
18#include <__concepts/invocable.h>
19#include <__concepts/referenceable.h>
20#include <__config>
21#include <__functional/bind_back.h>
22#include <__functional/invoke.h>
23#include <__functional/perfect_forward.h>
24#include <__iterator/concepts.h>
25#include <__iterator/iterator_traits.h>
26#include <__memory/addressof.h>
27#include <__ranges/access.h>
28#include <__ranges/all.h>
29#include <__ranges/concepts.h>
30#include <__ranges/empty.h>
31#include <__ranges/movable_box.h>
32#include <__ranges/range_adaptor.h>
33#include <__ranges/size.h>
34#include <__ranges/view_interface.h>
35#include <__type_traits/conditional.h>
36#include <__type_traits/decay.h>
37#include <__type_traits/invoke.h>
38#include <__type_traits/is_nothrow_constructible.h>
39#include <__type_traits/is_object.h>
40#include <__type_traits/is_reference.h>
41#include <__type_traits/maybe_const.h>
42#include <__type_traits/remove_cvref.h>
43#include <__utility/forward.h>
44#include <__utility/in_place.h>
45#include <__utility/move.h>
46
47#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
48# pragma GCC system_header
49#endif
50
51_LIBCPP_PUSH_MACROS
52#include <__undef_macros>
53
54_LIBCPP_BEGIN_NAMESPACE_STD
55
56#if _LIBCPP_STD_VER >= 20
57
58namespace ranges {
59
60template <class _Fn, class _View>
61concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_reference_t<_View>>;
62
63template <class _View, class _Fn>
64concept __transform_view_constraints =
65 view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> &&
66 __referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>;
67
68# if _LIBCPP_STD_VER >= 23
69template <input_range _View, move_constructible _Fn>
70# else
71template <input_range _View, copy_constructible _Fn>
72# endif
73 requires __transform_view_constraints<_View, _Fn>
74class _LIBCPP_LLVM18_NO_UNIQUE_ADDRESS_ABI_TAG transform_view : public view_interface<transform_view<_View, _Fn>> {
75 template <bool>
76 class __iterator;
77 template <bool>
78 class __sentinel;
79
80 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Fn> __func_;
81 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
82
83public:
84 _LIBCPP_HIDE_FROM_ABI transform_view()
85 requires default_initializable<_View> && default_initializable<_Fn>
86 = default;
87
88 _LIBCPP_HIDE_FROM_ABI constexpr explicit transform_view(_View __base, _Fn __func)
89 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {}
90
91 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
92 requires copy_constructible<_View>
93 {
94 return __base_;
95 }
96
97 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
98
99 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> begin() {
100 return __iterator<false>{*this, ranges::begin(__base_)};
101 }
102
103 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> begin() const
104 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
105 {
106 return __iterator<true>(*this, ranges::begin(__base_));
107 }
108
109 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<false> end() {
110 return __sentinel<false>(ranges::end(__base_));
111 }
112
113 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> end()
114 requires common_range<_View>
115 {
116 return __iterator<false>(*this, ranges::end(__base_));
117 }
118
119 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<true> end() const
120 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
121 {
122 return __sentinel<true>(ranges::end(__base_));
123 }
124
125 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> end() const
126 requires common_range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
127 {
128 return __iterator<true>(*this, ranges::end(__base_));
129 }
130
131 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto size()
132 requires sized_range<_View>
133 {
134 return ranges::size(__base_);
135 }
136
137 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
138 requires sized_range<const _View>
139 {
140 return ranges::size(__base_);
141 }
142};
143
144template <class _Range, class _Fn>
145transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>;
146
147template <class _View>
148struct __transform_view_iterator_concept {
149 using type _LIBCPP_NODEBUG = input_iterator_tag;
150};
151
152template <random_access_range _View>
153struct __transform_view_iterator_concept<_View> {
154 using type _LIBCPP_NODEBUG = random_access_iterator_tag;
155};
156
157template <bidirectional_range _View>
158struct __transform_view_iterator_concept<_View> {
159 using type _LIBCPP_NODEBUG = bidirectional_iterator_tag;
160};
161
162template <forward_range _View>
163struct __transform_view_iterator_concept<_View> {
164 using type _LIBCPP_NODEBUG = forward_iterator_tag;
165};
166
167template <class, class>
168struct __transform_view_iterator_category_base {};
169
170template <forward_range _View, class _Fn>
171struct __transform_view_iterator_category_base<_View, _Fn> {
172 using _Cat _LIBCPP_NODEBUG = typename iterator_traits<iterator_t<_View>>::iterator_category;
173
174 using iterator_category =
175 conditional_t< is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>,
176 conditional_t< derived_from<_Cat, contiguous_iterator_tag>, random_access_iterator_tag, _Cat >,
177 input_iterator_tag >;
178};
179
180# if _LIBCPP_STD_VER >= 23
181template <input_range _View, move_constructible _Fn>
182# else
183template <input_range _View, copy_constructible _Fn>
184# endif
185 requires __transform_view_constraints<_View, _Fn>
186template <bool _Const>
187class transform_view<_View, _Fn>::__iterator
188 : public __transform_view_iterator_category_base<_View, __maybe_const<_Const, _Fn>> {
189
190 using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, transform_view>;
191 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
192
193 _Parent* __parent_ = nullptr;
194
195 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current)
196 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {}
197
198 friend class transform_view<_View, _Fn>;
199
200 template <bool>
201 friend class transform_view<_View, _Fn>::__iterator;
202
203 template <bool>
204 friend class transform_view<_View, _Fn>::__sentinel;
205
206public:
207 iterator_t<_Base> __current_ = iterator_t<_Base>();
208
209 using iterator_concept = typename __transform_view_iterator_concept<_View>::type;
210 using value_type = remove_cvref_t<invoke_result_t<__maybe_const<_Const, _Fn>&, range_reference_t<_Base>>>;
211 using difference_type = range_difference_t<_Base>;
212
213 _LIBCPP_HIDE_FROM_ABI __iterator()
214 requires default_initializable<iterator_t<_Base>>
215 = default;
216
217 // Note: `__i` should always be `__iterator<false>`, but directly using
218 // `__iterator<false>` is ill-formed when `_Const` is false
219 // (see http://wg21.link/class.copy.ctor#5).
220 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
221 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
222 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {}
223
224 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; }
225
226 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); }
227
228 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const
229 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) {
230 return std::invoke(*__parent_->__func_, *__current_);
231 }
232
233 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
234 ++__current_;
235 return *this;
236 }
237
238 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; }
239
240 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
241 requires forward_range<_Base>
242 {
243 auto __tmp = *this;
244 ++*this;
245 return __tmp;
246 }
247
248 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
249 requires bidirectional_range<_Base>
250 {
251 --__current_;
252 return *this;
253 }
254
255 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
256 requires bidirectional_range<_Base>
257 {
258 auto __tmp = *this;
259 --*this;
260 return __tmp;
261 }
262
263 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n)
264 requires random_access_range<_Base>
265 {
266 __current_ += __n;
267 return *this;
268 }
269
270 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n)
271 requires random_access_range<_Base>
272 {
273 __current_ -= __n;
274 return *this;
275 }
276
277 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const
278 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n])))
279 requires random_access_range<_Base>
280 {
281 return std::invoke(*__parent_->__func_, __current_[__n]);
282 }
283
284 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
285 requires equality_comparable<iterator_t<_Base>>
286 {
287 return __x.__current_ == __y.__current_;
288 }
289
290 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
291 requires random_access_range<_Base>
292 {
293 return __x.__current_ < __y.__current_;
294 }
295
296 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
297 requires random_access_range<_Base>
298 {
299 return __x.__current_ > __y.__current_;
300 }
301
302 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
303 requires random_access_range<_Base>
304 {
305 return __x.__current_ <= __y.__current_;
306 }
307
308 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
309 requires random_access_range<_Base>
310 {
311 return __x.__current_ >= __y.__current_;
312 }
313
314 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
315 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
316 {
317 return __x.__current_ <=> __y.__current_;
318 }
319
320 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n)
321 requires random_access_range<_Base>
322 {
323 return __iterator{*__i.__parent_, __i.__current_ + __n};
324 }
325
326 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i)
327 requires random_access_range<_Base>
328 {
329 return __iterator{*__i.__parent_, __i.__current_ + __n};
330 }
331
332 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(__iterator __i, difference_type __n)
333 requires random_access_range<_Base>
334 {
335 return __iterator{*__i.__parent_, __i.__current_ - __n};
336 }
337
338 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type
339 operator-(const __iterator& __x, const __iterator& __y)
340 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
341 {
342 return __x.__current_ - __y.__current_;
343 }
344};
345
346# if _LIBCPP_STD_VER >= 23
347template <input_range _View, move_constructible _Fn>
348# else
349template <input_range _View, copy_constructible _Fn>
350# endif
351 requires __transform_view_constraints<_View, _Fn>
352template <bool _Const>
353class transform_view<_View, _Fn>::__sentinel {
354 using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, transform_view>;
355 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
356
357 sentinel_t<_Base> __end_ = sentinel_t<_Base>();
358
359 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {}
360
361 friend class transform_view<_View, _Fn>;
362
363 template <bool>
364 friend class transform_view<_View, _Fn>::__iterator;
365
366 template <bool>
367 friend class transform_view<_View, _Fn>::__sentinel;
368
369public:
370 _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
371
372 // Note: `__i` should always be `__sentinel<false>`, but directly using
373 // `__sentinel<false>` is ill-formed when `_Const` is false
374 // (see http://wg21.link/class.copy.ctor#5).
375 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i)
376 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
377 : __end_(std::move(__i.__end_)) {}
378
379 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
380
381 template <bool _OtherConst>
382 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
383 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
384 return __x.__current_ == __y.__end_;
385 }
386
387 template <bool _OtherConst>
388 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
389 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
390 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
391 return __x.__current_ - __y.__end_;
392 }
393
394 template <bool _OtherConst>
395 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
396 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
397 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) {
398 return __x.__end_ - __y.__current_;
399 }
400};
401
402namespace views {
403namespace __transform {
404struct __fn {
405 template <class _Range, class _Fn>
406 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Fn&& __f) const
407 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))))
408 -> decltype(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) {
409 return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f));
410 }
411
412 template <class _Fn>
413 requires constructible_from<decay_t<_Fn>, _Fn>
414 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f) const
415 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) {
416 return __pipeable(std::__bind_back(*this, std::forward<_Fn>(__f)));
417 }
418};
419} // namespace __transform
420
421inline namespace __cpo {
422inline constexpr auto transform = __transform::__fn{};
423} // namespace __cpo
424} // namespace views
425
426} // namespace ranges
427
428#endif // _LIBCPP_STD_VER >= 20
429
430_LIBCPP_END_NAMESPACE_STD
431
432_LIBCPP_POP_MACROS
433
434#endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H
435