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/copyable.h>
17#include <__concepts/derived_from.h>
18#include <__concepts/equality_comparable.h>
19#include <__concepts/invocable.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/is_referenceable.h>
42#include <__type_traits/maybe_const.h>
43#include <__type_traits/remove_cvref.h>
44#include <__utility/forward.h>
45#include <__utility/in_place.h>
46#include <__utility/move.h>
47
48#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
49# pragma GCC system_header
50#endif
51
52_LIBCPP_PUSH_MACROS
53#include <__undef_macros>
54
55_LIBCPP_BEGIN_NAMESPACE_STD
56
57#if _LIBCPP_STD_VER >= 20
58
59namespace ranges {
60
61template <class _Fn, class _View>
62concept __regular_invocable_with_range_ref = regular_invocable<_Fn, range_reference_t<_View>>;
63
64template <class _View, class _Fn>
65concept __transform_view_constraints =
66 view<_View> && is_object_v<_Fn> && regular_invocable<_Fn&, range_reference_t<_View>> &&
67 __is_referenceable_v<invoke_result_t<_Fn&, range_reference_t<_View>>>;
68
69# if _LIBCPP_STD_VER >= 23
70template <input_range _View, move_constructible _Fn>
71# else
72template <input_range _View, copy_constructible _Fn>
73# endif
74 requires __transform_view_constraints<_View, _Fn>
75class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS transform_view : public view_interface<transform_view<_View, _Fn>> {
76 template <bool>
77 class __iterator;
78 template <bool>
79 class __sentinel;
80
81 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Fn> __func_;
82 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
83
84public:
85 _LIBCPP_HIDE_FROM_ABI transform_view()
86 requires default_initializable<_View> && default_initializable<_Fn>
87 = default;
88
89 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 transform_view(_View __base, _Fn __func)
90 : __func_(std::in_place, std::move(__func)), __base_(std::move(__base)) {}
91
92 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
93 requires copy_constructible<_View>
94 {
95 return __base_;
96 }
97 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
98
99 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> begin() { return __iterator<false>{*this, ranges::begin(__base_)}; }
100 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> begin() const
101 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
102 {
103 return __iterator<true>(*this, ranges::begin(__base_));
104 }
105
106 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<false> end() { return __sentinel<false>(ranges::end(__base_)); }
107 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<false> end()
108 requires common_range<_View>
109 {
110 return __iterator<false>(*this, ranges::end(__base_));
111 }
112 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel<true> end() const
113 requires range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
114 {
115 return __sentinel<true>(ranges::end(__base_));
116 }
117 _LIBCPP_HIDE_FROM_ABI constexpr __iterator<true> end() const
118 requires common_range<const _View> && __regular_invocable_with_range_ref<const _Fn&, const _View>
119 {
120 return __iterator<true>(*this, ranges::end(__base_));
121 }
122
123 _LIBCPP_HIDE_FROM_ABI constexpr auto size()
124 requires sized_range<_View>
125 {
126 return ranges::size(__base_);
127 }
128 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
129 requires sized_range<const _View>
130 {
131 return ranges::size(__base_);
132 }
133};
134
135template <class _Range, class _Fn>
136transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>;
137
138template <class _View>
139struct __transform_view_iterator_concept {
140 using type _LIBCPP_NODEBUG = input_iterator_tag;
141};
142
143template <random_access_range _View>
144struct __transform_view_iterator_concept<_View> {
145 using type _LIBCPP_NODEBUG = random_access_iterator_tag;
146};
147
148template <bidirectional_range _View>
149struct __transform_view_iterator_concept<_View> {
150 using type _LIBCPP_NODEBUG = bidirectional_iterator_tag;
151};
152
153template <forward_range _View>
154struct __transform_view_iterator_concept<_View> {
155 using type _LIBCPP_NODEBUG = forward_iterator_tag;
156};
157
158template <class, class>
159struct __transform_view_iterator_category_base {};
160
161template <forward_range _View, class _Fn>
162struct __transform_view_iterator_category_base<_View, _Fn> {
163 using _Cat _LIBCPP_NODEBUG = typename iterator_traits<iterator_t<_View>>::iterator_category;
164
165 using iterator_category =
166 conditional_t< is_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>,
167 conditional_t< derived_from<_Cat, contiguous_iterator_tag>, random_access_iterator_tag, _Cat >,
168 input_iterator_tag >;
169};
170
171# if _LIBCPP_STD_VER >= 23
172template <input_range _View, move_constructible _Fn>
173# else
174template <input_range _View, copy_constructible _Fn>
175# endif
176 requires __transform_view_constraints<_View, _Fn>
177template <bool _Const>
178class transform_view<_View, _Fn>::__iterator
179 : public __transform_view_iterator_category_base<_View, __maybe_const<_Const, _Fn>> {
180
181 using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, transform_view>;
182 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
183
184 _Parent* __parent_ = nullptr;
185
186 template <bool>
187 friend class transform_view<_View, _Fn>::__iterator;
188
189 template <bool>
190 friend class transform_view<_View, _Fn>::__sentinel;
191
192public:
193 iterator_t<_Base> __current_ = iterator_t<_Base>();
194
195 using iterator_concept = typename __transform_view_iterator_concept<_View>::type;
196 using value_type = remove_cvref_t<invoke_result_t<__maybe_const<_Const, _Fn>&, range_reference_t<_Base>>>;
197 using difference_type = range_difference_t<_Base>;
198
199 _LIBCPP_HIDE_FROM_ABI __iterator()
200 requires default_initializable<iterator_t<_Base>>
201 = default;
202
203 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current)
204 : __parent_(std::addressof(__parent)), __current_(std::move(__current)) {}
205
206 // Note: `__i` should always be `__iterator<false>`, but directly using
207 // `__iterator<false>` is ill-formed when `_Const` is false
208 // (see http://wg21.link/class.copy.ctor#5).
209 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
210 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
211 : __parent_(__i.__parent_), __current_(std::move(__i.__current_)) {}
212
213 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; }
214
215 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); }
216
217 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const
218 noexcept(noexcept(std::invoke(*__parent_->__func_, *__current_))) {
219 return std::invoke(*__parent_->__func_, *__current_);
220 }
221
222 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
223 ++__current_;
224 return *this;
225 }
226
227 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; }
228
229 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
230 requires forward_range<_Base>
231 {
232 auto __tmp = *this;
233 ++*this;
234 return __tmp;
235 }
236
237 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
238 requires bidirectional_range<_Base>
239 {
240 --__current_;
241 return *this;
242 }
243
244 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
245 requires bidirectional_range<_Base>
246 {
247 auto __tmp = *this;
248 --*this;
249 return __tmp;
250 }
251
252 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n)
253 requires random_access_range<_Base>
254 {
255 __current_ += __n;
256 return *this;
257 }
258
259 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n)
260 requires random_access_range<_Base>
261 {
262 __current_ -= __n;
263 return *this;
264 }
265
266 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const
267 noexcept(noexcept(std::invoke(*__parent_->__func_, __current_[__n])))
268 requires random_access_range<_Base>
269 {
270 return std::invoke(*__parent_->__func_, __current_[__n]);
271 }
272
273 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
274 requires equality_comparable<iterator_t<_Base>>
275 {
276 return __x.__current_ == __y.__current_;
277 }
278
279 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
280 requires random_access_range<_Base>
281 {
282 return __x.__current_ < __y.__current_;
283 }
284
285 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
286 requires random_access_range<_Base>
287 {
288 return __x.__current_ > __y.__current_;
289 }
290
291 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
292 requires random_access_range<_Base>
293 {
294 return __x.__current_ <= __y.__current_;
295 }
296
297 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
298 requires random_access_range<_Base>
299 {
300 return __x.__current_ >= __y.__current_;
301 }
302
303 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
304 requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
305 {
306 return __x.__current_ <=> __y.__current_;
307 }
308
309 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n)
310 requires random_access_range<_Base>
311 {
312 return __iterator{*__i.__parent_, __i.__current_ + __n};
313 }
314
315 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i)
316 requires random_access_range<_Base>
317 {
318 return __iterator{*__i.__parent_, __i.__current_ + __n};
319 }
320
321 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(__iterator __i, difference_type __n)
322 requires random_access_range<_Base>
323 {
324 return __iterator{*__i.__parent_, __i.__current_ - __n};
325 }
326
327 _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
328 requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
329 {
330 return __x.__current_ - __y.__current_;
331 }
332};
333
334# if _LIBCPP_STD_VER >= 23
335template <input_range _View, move_constructible _Fn>
336# else
337template <input_range _View, copy_constructible _Fn>
338# endif
339 requires __transform_view_constraints<_View, _Fn>
340template <bool _Const>
341class transform_view<_View, _Fn>::__sentinel {
342 using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, transform_view>;
343 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
344
345 sentinel_t<_Base> __end_ = sentinel_t<_Base>();
346
347 template <bool>
348 friend class transform_view<_View, _Fn>::__iterator;
349
350 template <bool>
351 friend class transform_view<_View, _Fn>::__sentinel;
352
353public:
354 _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
355
356 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {}
357
358 // Note: `__i` should always be `__sentinel<false>`, but directly using
359 // `__sentinel<false>` is ill-formed when `_Const` is false
360 // (see http://wg21.link/class.copy.ctor#5).
361 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __i)
362 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
363 : __end_(std::move(__i.__end_)) {}
364
365 _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
366
367 template <bool _OtherConst>
368 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
369 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
370 return __x.__current_ == __y.__end_;
371 }
372
373 template <bool _OtherConst>
374 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
375 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
376 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
377 return __x.__current_ - __y.__end_;
378 }
379
380 template <bool _OtherConst>
381 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
382 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
383 operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) {
384 return __x.__end_ - __y.__current_;
385 }
386};
387
388namespace views {
389namespace __transform {
390struct __fn {
391 template <class _Range, class _Fn>
392 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Fn&& __f) const
393 noexcept(noexcept(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))))
394 -> decltype(transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f))) {
395 return transform_view(std::forward<_Range>(__range), std::forward<_Fn>(__f));
396 }
397
398 template <class _Fn>
399 requires constructible_from<decay_t<_Fn>, _Fn>
400 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn&& __f) const
401 noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>) {
402 return __pipeable(std::__bind_back(*this, std::forward<_Fn>(__f)));
403 }
404};
405} // namespace __transform
406
407inline namespace __cpo {
408inline constexpr auto transform = __transform::__fn{};
409} // namespace __cpo
410} // namespace views
411
412} // namespace ranges
413
414#endif // _LIBCPP_STD_VER >= 20
415
416_LIBCPP_END_NAMESPACE_STD
417
418_LIBCPP_POP_MACROS
419
420#endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H
421