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