source: Daodan/MSYS2/mingw32/include/c++/11.2.0/concepts@ 1166

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1// <concepts> -*- C++ -*-
2
3// Copyright (C) 2019-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/concepts
26 * This is a Standard C++ Library header.
27 * @ingroup concepts
28 */
29
30#ifndef _GLIBCXX_CONCEPTS
31#define _GLIBCXX_CONCEPTS 1
32
33#if __cplusplus > 201703L && __cpp_concepts >= 201907L
34
35#pragma GCC system_header
36
37/**
38 * @defgroup concepts Concepts
39 * @ingroup utilities
40 *
41 * Concepts for checking type requirements.
42 */
43
44#include <type_traits>
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50#define __cpp_lib_concepts 202002L
51
52 // [concepts.lang], language-related concepts
53
54 namespace __detail
55 {
56 template<typename _Tp, typename _Up>
57 concept __same_as = std::is_same_v<_Tp, _Up>;
58 } // namespace __detail
59
60 /// [concept.same], concept same_as
61 template<typename _Tp, typename _Up>
62 concept same_as
63 = __detail::__same_as<_Tp, _Up> && __detail::__same_as<_Up, _Tp>;
64
65 /// [concept.derived], concept derived_from
66 template<typename _Derived, typename _Base>
67 concept derived_from = __is_base_of(_Base, _Derived)
68 && is_convertible_v<const volatile _Derived*, const volatile _Base*>;
69
70 /// [concept.convertible], concept convertible_to
71 template<typename _From, typename _To>
72 concept convertible_to = is_convertible_v<_From, _To>
73 && requires(add_rvalue_reference_t<_From> (&__f)()) {
74 static_cast<_To>(__f());
75 };
76
77 /// [concept.commonref], concept common_reference_with
78 template<typename _Tp, typename _Up>
79 concept common_reference_with
80 = same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>>
81 && convertible_to<_Tp, common_reference_t<_Tp, _Up>>
82 && convertible_to<_Up, common_reference_t<_Tp, _Up>>;
83
84 /// [concept.common], concept common_with
85 template<typename _Tp, typename _Up>
86 concept common_with
87 = same_as<common_type_t<_Tp, _Up>, common_type_t<_Up, _Tp>>
88 && requires {
89 static_cast<common_type_t<_Tp, _Up>>(std::declval<_Tp>());
90 static_cast<common_type_t<_Tp, _Up>>(std::declval<_Up>());
91 }
92 && common_reference_with<add_lvalue_reference_t<const _Tp>,
93 add_lvalue_reference_t<const _Up>>
94 && common_reference_with<add_lvalue_reference_t<common_type_t<_Tp, _Up>>,
95 common_reference_t<
96 add_lvalue_reference_t<const _Tp>,
97 add_lvalue_reference_t<const _Up>>>;
98
99 // [concepts.arithmetic], arithmetic concepts
100
101 template<typename _Tp>
102 concept integral = is_integral_v<_Tp>;
103
104 template<typename _Tp>
105 concept signed_integral = integral<_Tp> && is_signed_v<_Tp>;
106
107 template<typename _Tp>
108 concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>;
109
110 template<typename _Tp>
111 concept floating_point = is_floating_point_v<_Tp>;
112
113 namespace __detail
114 {
115 template<typename _Tp>
116 using __cref = const remove_reference_t<_Tp>&;
117
118 template<typename _Tp>
119 concept __class_or_enum
120 = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;
121 } // namespace __detail
122
123 /// [concept.assignable], concept assignable_from
124 template<typename _Lhs, typename _Rhs>
125 concept assignable_from
126 = is_lvalue_reference_v<_Lhs>
127 && common_reference_with<__detail::__cref<_Lhs>, __detail::__cref<_Rhs>>
128 && requires(_Lhs __lhs, _Rhs&& __rhs) {
129 { __lhs = static_cast<_Rhs&&>(__rhs) } -> same_as<_Lhs>;
130 };
131
132 /// [concept.destructible], concept destructible
133 template<typename _Tp>
134 concept destructible = is_nothrow_destructible_v<_Tp>;
135
136 /// [concept.constructible], concept constructible_from
137 template<typename _Tp, typename... _Args>
138 concept constructible_from
139 = destructible<_Tp> && is_constructible_v<_Tp, _Args...>;
140
141 /// [concept.defaultinitializable], concept default_initializable
142 template<typename _Tp>
143 concept default_initializable = constructible_from<_Tp>
144 && requires
145 {
146 _Tp{};
147 (void) ::new _Tp;
148 };
149
150 /// [concept.moveconstructible], concept move_constructible
151 template<typename _Tp>
152 concept move_constructible
153 = constructible_from<_Tp, _Tp> && convertible_to<_Tp, _Tp>;
154
155 /// [concept.copyconstructible], concept copy_constructible
156 template<typename _Tp>
157 concept copy_constructible
158 = move_constructible<_Tp>
159 && constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp>
160 && constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp>
161 && constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
162
163 // [concept.swappable], concept swappable
164
165 namespace ranges
166 {
167 namespace __cust_swap
168 {
169 template<typename _Tp> void swap(_Tp&, _Tp&) = delete;
170
171 template<typename _Tp, typename _Up>
172 concept __adl_swap
173 = (__detail::__class_or_enum<remove_reference_t<_Tp>>
174 || __detail::__class_or_enum<remove_reference_t<_Up>>)
175 && requires(_Tp&& __t, _Up&& __u) {
176 swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
177 };
178
179 struct _Swap
180 {
181 private:
182 template<typename _Tp, typename _Up>
183 static constexpr bool
184 _S_noexcept()
185 {
186 if constexpr (__adl_swap<_Tp, _Up>)
187 return noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()));
188 else
189 return is_nothrow_move_constructible_v<remove_reference_t<_Tp>>
190 && is_nothrow_move_assignable_v<remove_reference_t<_Tp>>;
191 }
192
193 public:
194 template<typename _Tp, typename _Up>
195 requires __adl_swap<_Tp, _Up>
196 || (same_as<_Tp, _Up> && is_lvalue_reference_v<_Tp>
197 && move_constructible<remove_reference_t<_Tp>>
198 && assignable_from<_Tp, remove_reference_t<_Tp>>)
199 constexpr void
200 operator()(_Tp&& __t, _Up&& __u) const
201 noexcept(_S_noexcept<_Tp, _Up>())
202 {
203 if constexpr (__adl_swap<_Tp, _Up>)
204 swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
205 else
206 {
207 auto __tmp = static_cast<remove_reference_t<_Tp>&&>(__t);
208 __t = static_cast<remove_reference_t<_Tp>&&>(__u);
209 __u = static_cast<remove_reference_t<_Tp>&&>(__tmp);
210 }
211 }
212
213 template<typename _Tp, typename _Up, size_t _Num>
214 requires requires(const _Swap& __swap, _Tp& __e1, _Up& __e2) {
215 __swap(__e1, __e2);
216 }
217 constexpr void
218 operator()(_Tp (&__e1)[_Num], _Up (&__e2)[_Num]) const
219 noexcept(noexcept(std::declval<const _Swap&>()(*__e1, *__e2)))
220 {
221 for (size_t __n = 0; __n < _Num; ++__n)
222 (*this)(__e1[__n], __e2[__n]);
223 }
224 };
225 } // namespace __cust_swap
226
227 inline namespace __cust
228 {
229 inline constexpr __cust_swap::_Swap swap{};
230 } // inline namespace __cust
231 } // namespace ranges
232
233 template<typename _Tp>
234 concept swappable
235 = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); };
236
237 template<typename _Tp, typename _Up>
238 concept swappable_with = common_reference_with<_Tp, _Up>
239 && requires(_Tp&& __t, _Up&& __u) {
240 ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Tp&&>(__t));
241 ranges::swap(static_cast<_Up&&>(__u), static_cast<_Up&&>(__u));
242 ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
243 ranges::swap(static_cast<_Up&&>(__u), static_cast<_Tp&&>(__t));
244 };
245
246 // [concepts.object], Object concepts
247
248 template<typename _Tp>
249 concept movable = is_object_v<_Tp> && move_constructible<_Tp>
250 && assignable_from<_Tp&, _Tp> && swappable<_Tp>;
251
252 template<typename _Tp>
253 concept copyable = copy_constructible<_Tp> && movable<_Tp>
254 && assignable_from<_Tp&, _Tp&> && assignable_from<_Tp&, const _Tp&>
255 && assignable_from<_Tp&, const _Tp>;
256
257 template<typename _Tp>
258 concept semiregular = copyable<_Tp> && default_initializable<_Tp>;
259
260 // [concepts.compare], comparison concepts
261
262 // [concept.booleantestable], Boolean testability
263 namespace __detail
264 {
265 template<typename _Tp>
266 concept __boolean_testable_impl = convertible_to<_Tp, bool>;
267
268 template<typename _Tp>
269 concept __boolean_testable
270 = __boolean_testable_impl<_Tp>
271 && requires(_Tp&& __t)
272 { { !static_cast<_Tp&&>(__t) } -> __boolean_testable_impl; };
273 } // namespace __detail
274
275 // [concept.equalitycomparable], concept equality_comparable
276
277 namespace __detail
278 {
279 template<typename _Tp, typename _Up>
280 concept __weakly_eq_cmp_with
281 = requires(__detail::__cref<_Tp> __t, __detail::__cref<_Up> __u) {
282 { __t == __u } -> __boolean_testable;
283 { __t != __u } -> __boolean_testable;
284 { __u == __t } -> __boolean_testable;
285 { __u != __t } -> __boolean_testable;
286 };
287 } // namespace __detail
288
289 template<typename _Tp>
290 concept equality_comparable = __detail::__weakly_eq_cmp_with<_Tp, _Tp>;
291
292 template<typename _Tp, typename _Up>
293 concept equality_comparable_with
294 = equality_comparable<_Tp> && equality_comparable<_Up>
295 && common_reference_with<__detail::__cref<_Tp>, __detail::__cref<_Up>>
296 && equality_comparable<common_reference_t<__detail::__cref<_Tp>,
297 __detail::__cref<_Up>>>
298 && __detail::__weakly_eq_cmp_with<_Tp, _Up>;
299
300 namespace __detail
301 {
302 template<typename _Tp, typename _Up>
303 concept __partially_ordered_with
304 = requires(const remove_reference_t<_Tp>& __t,
305 const remove_reference_t<_Up>& __u) {
306 { __t < __u } -> __boolean_testable;
307 { __t > __u } -> __boolean_testable;
308 { __t <= __u } -> __boolean_testable;
309 { __t >= __u } -> __boolean_testable;
310 { __u < __t } -> __boolean_testable;
311 { __u > __t } -> __boolean_testable;
312 { __u <= __t } -> __boolean_testable;
313 { __u >= __t } -> __boolean_testable;
314 };
315 } // namespace __detail
316
317 // [concept.totallyordered], concept totally_ordered
318 template<typename _Tp>
319 concept totally_ordered
320 = equality_comparable<_Tp>
321 && __detail::__partially_ordered_with<_Tp, _Tp>;
322
323 template<typename _Tp, typename _Up>
324 concept totally_ordered_with
325 = totally_ordered<_Tp> && totally_ordered<_Up>
326 && equality_comparable_with<_Tp, _Up>
327 && totally_ordered<common_reference_t<__detail::__cref<_Tp>,
328 __detail::__cref<_Up>>>
329 && __detail::__partially_ordered_with<_Tp, _Up>;
330
331 template<typename _Tp>
332 concept regular = semiregular<_Tp> && equality_comparable<_Tp>;
333
334 // [concepts.callable], callable concepts
335
336 /// [concept.invocable], concept invocable
337 template<typename _Fn, typename... _Args>
338 concept invocable = is_invocable_v<_Fn, _Args...>;
339
340 /// [concept.regularinvocable], concept regular_invocable
341 template<typename _Fn, typename... _Args>
342 concept regular_invocable = invocable<_Fn, _Args...>;
343
344 /// [concept.predicate], concept predicate
345 template<typename _Fn, typename... _Args>
346 concept predicate = regular_invocable<_Fn, _Args...>
347 && __detail::__boolean_testable<invoke_result_t<_Fn, _Args...>>;
348
349 /// [concept.relation], concept relation
350 template<typename _Rel, typename _Tp, typename _Up>
351 concept relation
352 = predicate<_Rel, _Tp, _Tp> && predicate<_Rel, _Up, _Up>
353 && predicate<_Rel, _Tp, _Up> && predicate<_Rel, _Up, _Tp>;
354
355 /// [concept.equiv], concept equivalence_relation
356 template<typename _Rel, typename _Tp, typename _Up>
357 concept equivalence_relation = relation<_Rel, _Tp, _Up>;
358
359 /// [concept.strictweakorder], concept strict_weak_order
360 template<typename _Rel, typename _Tp, typename _Up>
361 concept strict_weak_order = relation<_Rel, _Tp, _Up>;
362
363_GLIBCXX_END_NAMESPACE_VERSION
364} // namespace
365#endif // C++2a
366
367#endif /* _GLIBCXX_CONCEPTS */
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