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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 :
46 : namespace 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 { static_cast<_To>(std::declval<_From>()); };
74 :
75 : /// [concept.commonref], concept common_reference_with
76 : template<typename _Tp, typename _Up>
77 : concept common_reference_with
78 : = same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>>
79 : && convertible_to<_Tp, common_reference_t<_Tp, _Up>>
80 : && convertible_to<_Up, common_reference_t<_Tp, _Up>>;
81 :
82 : /// [concept.common], concept common_with
83 : template<typename _Tp, typename _Up>
84 : concept common_with
85 : = same_as<common_type_t<_Tp, _Up>, common_type_t<_Up, _Tp>>
86 : && requires {
87 : static_cast<common_type_t<_Tp, _Up>>(std::declval<_Tp>());
88 : static_cast<common_type_t<_Tp, _Up>>(std::declval<_Up>());
89 : }
90 : && common_reference_with<add_lvalue_reference_t<const _Tp>,
91 : add_lvalue_reference_t<const _Up>>
92 : && common_reference_with<add_lvalue_reference_t<common_type_t<_Tp, _Up>>,
93 : common_reference_t<
94 : add_lvalue_reference_t<const _Tp>,
95 : add_lvalue_reference_t<const _Up>>>;
96 :
97 : // [concepts.arithmetic], arithmetic concepts
98 :
99 : template<typename _Tp>
100 : concept integral = is_integral_v<_Tp>;
101 :
102 : template<typename _Tp>
103 : concept signed_integral = integral<_Tp> && is_signed_v<_Tp>;
104 :
105 : template<typename _Tp>
106 : concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>;
107 :
108 : template<typename _Tp>
109 : concept floating_point = is_floating_point_v<_Tp>;
110 :
111 : namespace __detail
112 : {
113 : template<typename _Tp>
114 : using __cref = const remove_reference_t<_Tp>&;
115 :
116 : template<typename _Tp>
117 : concept __class_or_enum
118 : = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>;
119 : } // namespace __detail
120 :
121 : /// [concept.assignable], concept assignable_from
122 : template<typename _Lhs, typename _Rhs>
123 : concept assignable_from
124 : = is_lvalue_reference_v<_Lhs>
125 : && common_reference_with<__detail::__cref<_Lhs>, __detail::__cref<_Rhs>>
126 : && requires(_Lhs __lhs, _Rhs&& __rhs) {
127 : { __lhs = static_cast<_Rhs&&>(__rhs) } -> same_as<_Lhs>;
128 : };
129 :
130 : /// [concept.destructible], concept destructible
131 : template<typename _Tp>
132 : concept destructible = is_nothrow_destructible_v<_Tp>;
133 :
134 : /// [concept.constructible], concept constructible_from
135 : template<typename _Tp, typename... _Args>
136 : concept constructible_from
137 : = destructible<_Tp> && is_constructible_v<_Tp, _Args...>;
138 :
139 : /// [concept.defaultinitializable], concept default_initializable
140 : template<typename _Tp>
141 : concept default_initializable = constructible_from<_Tp>
142 : && requires
143 : {
144 : _Tp{};
145 : (void) ::new _Tp;
146 : };
147 :
148 : /// [concept.moveconstructible], concept move_constructible
149 : template<typename _Tp>
150 : concept move_constructible
151 : = constructible_from<_Tp, _Tp> && convertible_to<_Tp, _Tp>;
152 :
153 : /// [concept.copyconstructible], concept copy_constructible
154 : template<typename _Tp>
155 : concept copy_constructible
156 : = move_constructible<_Tp>
157 : && constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp>
158 : && constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp>
159 : && constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
160 :
161 : // [concept.swappable], concept swappable
162 :
163 : namespace ranges
164 : {
165 : namespace __cust_swap
166 : {
167 : template<typename _Tp> void swap(_Tp&, _Tp&) = delete;
168 :
169 : template<typename _Tp, typename _Up>
170 : concept __adl_swap
171 : = (__detail::__class_or_enum<remove_reference_t<_Tp>>
172 : || __detail::__class_or_enum<remove_reference_t<_Up>>)
173 : && requires(_Tp&& __t, _Up&& __u) {
174 : swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
175 : };
176 :
177 : struct _Swap
178 : {
179 : private:
180 : template<typename _Tp, typename _Up>
181 : static constexpr bool
182 : _S_noexcept()
183 : {
184 : if constexpr (__adl_swap<_Tp, _Up>)
185 : return noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()));
186 : else
187 : return is_nothrow_move_constructible_v<remove_reference_t<_Tp>>
188 : && is_nothrow_move_assignable_v<remove_reference_t<_Tp>>;
189 : }
190 :
191 : public:
192 : template<typename _Tp, typename _Up>
193 : requires __adl_swap<_Tp, _Up>
194 : || (same_as<_Tp, _Up> && is_lvalue_reference_v<_Tp>
195 : && move_constructible<remove_reference_t<_Tp>>
196 : && assignable_from<_Tp, remove_reference_t<_Tp>>)
197 : constexpr void
198 0 : operator()(_Tp&& __t, _Up&& __u) const
199 : noexcept(_S_noexcept<_Tp, _Up>())
200 : {
201 : if constexpr (__adl_swap<_Tp, _Up>)
202 : swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
203 : else
204 : {
205 0 : auto __tmp = static_cast<remove_reference_t<_Tp>&&>(__t);
206 0 : __t = static_cast<remove_reference_t<_Tp>&&>(__u);
207 0 : __u = static_cast<remove_reference_t<_Tp>&&>(__tmp);
208 0 : }
209 0 : }
210 :
211 : template<typename _Tp, typename _Up, size_t _Num>
212 : requires requires(const _Swap& __swap, _Tp& __e1, _Up& __e2) {
213 : __swap(__e1, __e2);
214 : }
215 : constexpr void
216 : operator()(_Tp (&__e1)[_Num], _Up (&__e2)[_Num]) const
217 : noexcept(noexcept(std::declval<const _Swap&>()(*__e1, *__e2)))
218 : {
219 : for (size_t __n = 0; __n < _Num; ++__n)
220 : (*this)(__e1[__n], __e2[__n]);
221 : }
222 : };
223 : } // namespace __cust_swap
224 :
225 : inline namespace __cust
226 : {
227 : inline constexpr __cust_swap::_Swap swap{};
228 : } // inline namespace __cust
229 : } // namespace ranges
230 :
231 : template<typename _Tp>
232 : concept swappable
233 : = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); };
234 :
235 : template<typename _Tp, typename _Up>
236 : concept swappable_with = common_reference_with<_Tp, _Up>
237 : && requires(_Tp&& __t, _Up&& __u) {
238 : ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Tp&&>(__t));
239 : ranges::swap(static_cast<_Up&&>(__u), static_cast<_Up&&>(__u));
240 : ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
241 : ranges::swap(static_cast<_Up&&>(__u), static_cast<_Tp&&>(__t));
242 : };
243 :
244 : // [concepts.object], Object concepts
245 :
246 : template<typename _Tp>
247 : concept movable = is_object_v<_Tp> && move_constructible<_Tp>
248 : && assignable_from<_Tp&, _Tp> && swappable<_Tp>;
249 :
250 : template<typename _Tp>
251 : concept copyable = copy_constructible<_Tp> && movable<_Tp>
252 : && assignable_from<_Tp&, _Tp&> && assignable_from<_Tp&, const _Tp&>
253 : && assignable_from<_Tp&, const _Tp>;
254 :
255 : template<typename _Tp>
256 : concept semiregular = copyable<_Tp> && default_initializable<_Tp>;
257 :
258 : // [concepts.compare], comparison concepts
259 :
260 : // [concept.booleantestable], Boolean testability
261 : namespace __detail
262 : {
263 : template<typename _Tp>
264 : concept __boolean_testable_impl = convertible_to<_Tp, bool>;
265 :
266 : template<typename _Tp>
267 : concept __boolean_testable
268 : = __boolean_testable_impl<_Tp>
269 : && requires(_Tp&& __t)
270 : { { !static_cast<_Tp&&>(__t) } -> __boolean_testable_impl; };
271 : } // namespace __detail
272 :
273 : // [concept.equalitycomparable], concept equality_comparable
274 :
275 : namespace __detail
276 : {
277 : template<typename _Tp, typename _Up>
278 : concept __weakly_eq_cmp_with
279 : = requires(__detail::__cref<_Tp> __t, __detail::__cref<_Up> __u) {
280 : { __t == __u } -> __boolean_testable;
281 : { __t != __u } -> __boolean_testable;
282 : { __u == __t } -> __boolean_testable;
283 : { __u != __t } -> __boolean_testable;
284 : };
285 : } // namespace __detail
286 :
287 : template<typename _Tp>
288 : concept equality_comparable = __detail::__weakly_eq_cmp_with<_Tp, _Tp>;
289 :
290 : template<typename _Tp, typename _Up>
291 : concept equality_comparable_with
292 : = equality_comparable<_Tp> && equality_comparable<_Up>
293 : && common_reference_with<__detail::__cref<_Tp>, __detail::__cref<_Up>>
294 : && equality_comparable<common_reference_t<__detail::__cref<_Tp>,
295 : __detail::__cref<_Up>>>
296 : && __detail::__weakly_eq_cmp_with<_Tp, _Up>;
297 :
298 : namespace __detail
299 : {
300 : template<typename _Tp, typename _Up>
301 : concept __partially_ordered_with
302 : = requires(const remove_reference_t<_Tp>& __t,
303 : const remove_reference_t<_Up>& __u) {
304 : { __t < __u } -> __boolean_testable;
305 : { __t > __u } -> __boolean_testable;
306 : { __t <= __u } -> __boolean_testable;
307 : { __t >= __u } -> __boolean_testable;
308 : { __u < __t } -> __boolean_testable;
309 : { __u > __t } -> __boolean_testable;
310 : { __u <= __t } -> __boolean_testable;
311 : { __u >= __t } -> __boolean_testable;
312 : };
313 : } // namespace __detail
314 :
315 : // [concept.totallyordered], concept totally_ordered
316 : template<typename _Tp>
317 : concept totally_ordered
318 : = equality_comparable<_Tp>
319 : && __detail::__partially_ordered_with<_Tp, _Tp>;
320 :
321 : template<typename _Tp, typename _Up>
322 : concept totally_ordered_with
323 : = totally_ordered<_Tp> && totally_ordered<_Up>
324 : && equality_comparable_with<_Tp, _Up>
325 : && totally_ordered<common_reference_t<__detail::__cref<_Tp>,
326 : __detail::__cref<_Up>>>
327 : && __detail::__partially_ordered_with<_Tp, _Up>;
328 :
329 : template<typename _Tp>
330 : concept regular = semiregular<_Tp> && equality_comparable<_Tp>;
331 :
332 : // [concepts.callable], callable concepts
333 :
334 : /// [concept.invocable], concept invocable
335 : template<typename _Fn, typename... _Args>
336 : concept invocable = is_invocable_v<_Fn, _Args...>;
337 :
338 : /// [concept.regularinvocable], concept regular_invocable
339 : template<typename _Fn, typename... _Args>
340 : concept regular_invocable = invocable<_Fn, _Args...>;
341 :
342 : /// [concept.predicate], concept predicate
343 : template<typename _Fn, typename... _Args>
344 : concept predicate = regular_invocable<_Fn, _Args...>
345 : && __detail::__boolean_testable<invoke_result_t<_Fn, _Args...>>;
346 :
347 : /// [concept.relation], concept relation
348 : template<typename _Rel, typename _Tp, typename _Up>
349 : concept relation
350 : = predicate<_Rel, _Tp, _Tp> && predicate<_Rel, _Up, _Up>
351 : && predicate<_Rel, _Tp, _Up> && predicate<_Rel, _Up, _Tp>;
352 :
353 : /// [concept.equiv], concept equivalence_relation
354 : template<typename _Rel, typename _Tp, typename _Up>
355 : concept equivalence_relation = relation<_Rel, _Tp, _Up>;
356 :
357 : /// [concept.strictweakorder], concept strict_weak_order
358 : template<typename _Rel, typename _Tp, typename _Up>
359 : concept strict_weak_order = relation<_Rel, _Tp, _Up>;
360 :
361 : _GLIBCXX_END_NAMESPACE_VERSION
362 : } // namespace
363 : #endif // C++2a
364 :
365 : #endif /* _GLIBCXX_CONCEPTS */
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