master
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_ELEMENTS_VIEW_H
11#define _LIBCPP___RANGES_ELEMENTS_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 <__config>
19#include <__fwd/get.h>
20#include <__iterator/concepts.h>
21#include <__iterator/iterator_traits.h>
22#include <__ranges/access.h>
23#include <__ranges/all.h>
24#include <__ranges/concepts.h>
25#include <__ranges/enable_borrowed_range.h>
26#include <__ranges/range_adaptor.h>
27#include <__ranges/size.h>
28#include <__ranges/view_interface.h>
29#include <__tuple/tuple_element.h>
30#include <__tuple/tuple_like.h>
31#include <__tuple/tuple_size.h>
32#include <__type_traits/is_reference.h>
33#include <__type_traits/maybe_const.h>
34#include <__type_traits/remove_cv.h>
35#include <__type_traits/remove_cvref.h>
36#include <__type_traits/remove_reference.h>
37#include <__utility/declval.h>
38#include <__utility/forward.h>
39#include <__utility/move.h>
40#include <tuple> // std::get
41
42#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
43# pragma GCC system_header
44#endif
45
46_LIBCPP_PUSH_MACROS
47#include <__undef_macros>
48
49_LIBCPP_BEGIN_NAMESPACE_STD
50
51#if _LIBCPP_STD_VER >= 20
52
53namespace ranges {
54
55template <class _Tp, size_t _Np>
56concept __has_tuple_element = __tuple_like<_Tp> && _Np < tuple_size<_Tp>::value;
57
58template <class _Tp, size_t _Np>
59concept __returnable_element = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Np, _Tp>>;
60
61template <input_range _View, size_t _Np>
62 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> &&
63 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> &&
64 __returnable_element<range_reference_t<_View>, _Np>
65class elements_view : public view_interface<elements_view<_View, _Np>> {
66private:
67 template <bool>
68 class __iterator;
69
70 template <bool>
71 class __sentinel;
72
73public:
74 _LIBCPP_HIDE_FROM_ABI elements_view()
75 requires default_initializable<_View>
76 = default;
77
78 _LIBCPP_HIDE_FROM_ABI constexpr explicit elements_view(_View __base) : __base_(std::move(__base)) {}
79
80 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
81 requires copy_constructible<_View>
82 {
83 return __base_;
84 }
85
86 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
87
88 _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
89 requires(!__simple_view<_View>)
90 {
91 return __iterator</*_Const=*/false>(ranges::begin(__base_));
92 }
93
94 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
95 requires range<const _View>
96 {
97 return __iterator</*_Const=*/true>(ranges::begin(__base_));
98 }
99
100 _LIBCPP_HIDE_FROM_ABI constexpr auto end()
101 requires(!__simple_view<_View> && !common_range<_View>)
102 {
103 return __sentinel</*_Const=*/false>{ranges::end(__base_)};
104 }
105
106 _LIBCPP_HIDE_FROM_ABI constexpr auto end()
107 requires(!__simple_view<_View> && common_range<_View>)
108 {
109 return __iterator</*_Const=*/false>{ranges::end(__base_)};
110 }
111
112 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
113 requires range<const _View>
114 {
115 return __sentinel</*_Const=*/true>{ranges::end(__base_)};
116 }
117
118 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
119 requires common_range<const _View>
120 {
121 return __iterator</*_Const=*/true>{ranges::end(__base_)};
122 }
123
124 _LIBCPP_HIDE_FROM_ABI constexpr auto size()
125 requires sized_range<_View>
126 {
127 return ranges::size(__base_);
128 }
129
130 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
131 requires sized_range<const _View>
132 {
133 return ranges::size(__base_);
134 }
135
136private:
137 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
138};
139
140template <class, size_t>
141struct __elements_view_iterator_category_base {};
142
143template <forward_range _Base, size_t _Np>
144struct __elements_view_iterator_category_base<_Base, _Np> {
145 static consteval auto __get_iterator_category() {
146 using _Result = decltype(std::get<_Np>(*std::declval<iterator_t<_Base>>()));
147 using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category;
148
149 if constexpr (!is_lvalue_reference_v<_Result>) {
150 return input_iterator_tag{};
151 } else if constexpr (derived_from<_Cat, random_access_iterator_tag>) {
152 return random_access_iterator_tag{};
153 } else {
154 return _Cat{};
155 }
156 }
157
158 using iterator_category = decltype(__get_iterator_category());
159};
160
161template <input_range _View, size_t _Np>
162 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> &&
163 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> &&
164 __returnable_element<range_reference_t<_View>, _Np>
165template <bool _Const>
166class elements_view<_View, _Np>::__iterator
167 : public __elements_view_iterator_category_base<__maybe_const<_Const, _View>, _Np> {
168 template <bool>
169 friend class __iterator;
170
171 template <bool>
172 friend class __sentinel;
173
174 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
175
176 iterator_t<_Base> __current_ = iterator_t<_Base>();
177
178 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __get_element(const iterator_t<_Base>& __i) {
179 if constexpr (is_reference_v<range_reference_t<_Base>>) {
180 return std::get<_Np>(*__i);
181 } else {
182 using _Element = remove_cv_t<tuple_element_t<_Np, range_reference_t<_Base>>>;
183 return static_cast<_Element>(std::get<_Np>(*__i));
184 }
185 }
186
187 static consteval auto __get_iterator_concept() {
188 if constexpr (random_access_range<_Base>) {
189 return random_access_iterator_tag{};
190 } else if constexpr (bidirectional_range<_Base>) {
191 return bidirectional_iterator_tag{};
192 } else if constexpr (forward_range<_Base>) {
193 return forward_iterator_tag{};
194 } else {
195 return input_iterator_tag{};
196 }
197 }
198
199public:
200 using iterator_concept = decltype(__iterator::__get_iterator_concept());
201 using value_type = remove_cvref_t<tuple_element_t<_Np, range_value_t<_Base>>>;
202 using difference_type = range_difference_t<_Base>;
203
204 _LIBCPP_HIDE_FROM_ABI __iterator()
205 requires default_initializable<iterator_t<_Base>>
206 = default;
207
208 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(iterator_t<_Base> __current) : __current_(std::move(__current)) {}
209
210 _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
211 requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
212 : __current_(std::move(__i.__current_)) {}
213
214 _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; }
215
216 _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); }
217
218 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const { return __get_element(__current_); }
219
220 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
221 ++__current_;
222 return *this;
223 }
224
225 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; }
226
227 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
228 requires forward_range<_Base>
229 {
230 auto __temp = *this;
231 ++__current_;
232 return __temp;
233 }
234
235 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
236 requires bidirectional_range<_Base>
237 {
238 --__current_;
239 return *this;
240 }
241
242 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
243 requires bidirectional_range<_Base>
244 {
245 auto __temp = *this;
246 --__current_;
247 return __temp;
248 }
249
250 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n)
251 requires random_access_range<_Base>
252 {
253 __current_ += __n;
254 return *this;
255 }
256
257 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n)
258 requires random_access_range<_Base>
259 {
260 __current_ -= __n;
261 return *this;
262 }
263
264 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const
265 requires random_access_range<_Base>
266 {
267 return __get_element(__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 __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 !(__y < __x);
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 < __y);
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+(const __iterator& __x, difference_type __y)
307 requires random_access_range<_Base>
308 {
309 return __iterator{__x} += __y;
310 }
311
312 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __x, const __iterator& __y)
313 requires random_access_range<_Base>
314 {
315 return __y + __x;
316 }
317
318 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(const __iterator& __x, difference_type __y)
319 requires random_access_range<_Base>
320 {
321 return __iterator{__x} -= __y;
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
331template <input_range _View, size_t _Np>
332 requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> &&
333 __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> &&
334 __returnable_element<range_reference_t<_View>, _Np>
335template <bool _Const>
336class elements_view<_View, _Np>::__sentinel {
337private:
338 using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
339 _LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_Base> __end_ = sentinel_t<_Base>();
340
341 template <bool>
342 friend class __sentinel;
343
344 template <bool _AnyConst>
345 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __get_current(const __iterator<_AnyConst>& __iter) {
346 return (__iter.__current_);
347 }
348
349public:
350 _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
351
352 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(std::move(__end)) {}
353
354 _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __other)
355 requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
356 : __end_(std::move(__other.__end_)) {}
357
358 _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
359
360 template <bool _OtherConst>
361 requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
362 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
363 return __get_current(__x) == __y.__end_;
364 }
365
366 template <bool _OtherConst>
367 requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
368 _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
369 operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
370 return __get_current(__x) - __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 __sentinel& __x, const __iterator<_OtherConst>& __y) {
377 return __x.__end_ - __get_current(__y);
378 }
379};
380
381template <class _Tp, size_t _Np>
382inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Np>> = enable_borrowed_range<_Tp>;
383
384template <class _Tp>
385using keys_view = elements_view<_Tp, 0>;
386template <class _Tp>
387using values_view = elements_view<_Tp, 1>;
388
389namespace views {
390namespace __elements {
391
392template <size_t _Np>
393struct __fn : __range_adaptor_closure<__fn<_Np>> {
394 template <class _Range>
395 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const
396 /**/ noexcept(noexcept(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range))))
397 /*------*/ -> decltype(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range))) {
398 /*-------------*/ return elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range));
399 }
400};
401} // namespace __elements
402
403inline namespace __cpo {
404template <size_t _Np>
405inline constexpr auto elements = __elements::__fn<_Np>{};
406inline constexpr auto keys = elements<0>;
407inline constexpr auto values = elements<1>;
408} // namespace __cpo
409} // namespace views
410} // namespace ranges
411
412#endif // _LIBCPP_STD_VER >= 20
413
414_LIBCPP_END_NAMESPACE_STD
415
416_LIBCPP_POP_MACROS
417
418#endif // _LIBCPP___RANGES_ELEMENTS_VIEW_H