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The C and C++ Include Header Files
cat -n /usr/include/c++/15/concepts
1 // <concepts> -*- C++ -*- 2 3 // Copyright (C) 2019-2025 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 #ifdef _GLIBCXX_SYSHDR 34 #pragma GCC system_header 35 #endif 36 37 #define __glibcxx_want_concepts 38 #include <bits/version.h> 39 40 #ifdef __cpp_lib_concepts // C++ >= 20 && concepts 41 /** 42 * @defgroup concepts Concepts 43 * @ingroup utilities 44 * 45 * Concepts for checking type requirements. 46 */ 47 48 #include <type_traits> 49 50 namespace std _GLIBCXX_VISIBILITY(default) 51 { 52 _GLIBCXX_BEGIN_NAMESPACE_VERSION 53 54 // [concepts.lang], language-related concepts 55 56 namespace __detail 57 { 58 template<typename _Tp, typename _Up> 59 concept __same_as = std::is_same_v<_Tp, _Up>; 60 } // namespace __detail 61 62 /// [concept.same], concept same_as 63 template<typename _Tp, typename _Up> 64 concept same_as 65 = __detail::__same_as<_Tp, _Up> && __detail::__same_as<_Up, _Tp>; 66 67 namespace __detail 68 { 69 template<typename _Tp, typename _Up> 70 concept __different_from 71 = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>; 72 } // namespace __detail 73 74 /// [concept.derived], concept derived_from 75 template<typename _Derived, typename _Base> 76 concept derived_from = __is_base_of(_Base, _Derived) 77 && is_convertible_v<const volatile _Derived*, const volatile _Base*>; 78 79 /// [concept.convertible], concept convertible_to 80 template<typename _From, typename _To> 81 concept convertible_to = is_convertible_v<_From, _To> 82 && requires { static_cast<_To>(std::declval<_From>()); }; 83 84 /// [concept.commonref], concept common_reference_with 85 template<typename _Tp, typename _Up> 86 concept common_reference_with 87 = same_as<common_reference_t<_Tp, _Up>, common_reference_t<_Up, _Tp>> 88 && convertible_to<_Tp, common_reference_t<_Tp, _Up>> 89 && convertible_to<_Up, common_reference_t<_Tp, _Up>>; 90 91 /// [concept.common], concept common_with 92 template<typename _Tp, typename _Up> 93 concept common_with 94 = same_as<common_type_t<_Tp, _Up>, common_type_t<_Up, _Tp>> 95 && requires { 96 static_cast<common_type_t<_Tp, _Up>>(std::declval<_Tp>()); 97 static_cast<common_type_t<_Tp, _Up>>(std::declval<_Up>()); 98 } 99 && common_reference_with<add_lvalue_reference_t<const _Tp>, 100 add_lvalue_reference_t<const _Up>> 101 && common_reference_with<add_lvalue_reference_t<common_type_t<_Tp, _Up>>, 102 common_reference_t< 103 add_lvalue_reference_t<const _Tp>, 104 add_lvalue_reference_t<const _Up>>>; 105 106 // [concepts.arithmetic], arithmetic concepts 107 108 template<typename _Tp> 109 concept integral = is_integral_v<_Tp>; 110 111 template<typename _Tp> 112 concept signed_integral = integral<_Tp> && is_signed_v<_Tp>; 113 114 template<typename _Tp> 115 concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>; 116 117 template<typename _Tp> 118 concept floating_point = is_floating_point_v<_Tp>; 119 120 namespace __detail 121 { 122 template<typename _Tp> 123 using __cref = const remove_reference_t<_Tp>&; 124 125 template<typename _Tp> 126 concept __class_or_enum 127 = is_class_v<_Tp> || is_union_v<_Tp> || is_enum_v<_Tp>; 128 129 template<typename _Tp> 130 constexpr bool __destructible_impl = false; 131 template<typename _Tp> 132 requires requires(_Tp& __t) { { __t.~_Tp() } noexcept; } 133 constexpr bool __destructible_impl<_Tp> = true; 134 135 template<typename _Tp> 136 constexpr bool __destructible = __destructible_impl<_Tp>; 137 template<typename _Tp> 138 constexpr bool __destructible<_Tp&> = true; 139 template<typename _Tp> 140 constexpr bool __destructible<_Tp&&> = true; 141 template<typename _Tp, size_t _Nm> 142 constexpr bool __destructible<_Tp[_Nm]> = __destructible<_Tp>; 143 144 } // namespace __detail 145 146 /// [concept.assignable], concept assignable_from 147 template<typename _Lhs, typename _Rhs> 148 concept assignable_from 149 = is_lvalue_reference_v<_Lhs> 150 && common_reference_with<__detail::__cref<_Lhs>, __detail::__cref<_Rhs>> 151 && requires(_Lhs __lhs, _Rhs&& __rhs) { 152 { __lhs = static_cast<_Rhs&&>(__rhs) } -> same_as<_Lhs>; 153 }; 154 155 /// [concept.destructible], concept destructible 156 template<typename _Tp> 157 concept destructible = __detail::__destructible<_Tp>; 158 159 /// [concept.constructible], concept constructible_from 160 template<typename _Tp, typename... _Args> 161 concept constructible_from 162 = destructible<_Tp> && is_constructible_v<_Tp, _Args...>; 163 164 /// [concept.defaultinitializable], concept default_initializable 165 template<typename _Tp> 166 concept default_initializable = constructible_from<_Tp> 167 && requires 168 { 169 _Tp{}; 170 (void) ::new _Tp; 171 }; 172 173 /// [concept.moveconstructible], concept move_constructible 174 template<typename _Tp> 175 concept move_constructible 176 = constructible_from<_Tp, _Tp> && convertible_to<_Tp, _Tp>; 177 178 /// [concept.copyconstructible], concept copy_constructible 179 template<typename _Tp> 180 concept copy_constructible 181 = move_constructible<_Tp> 182 && constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp> 183 && constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp> 184 && constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>; 185 186 // [concept.swappable], concept swappable 187 188 namespace ranges 189 { 190 /// @cond undocumented 191 namespace __swap 192 { 193 template<typename _Tp> void swap(_Tp&, _Tp&) = delete; 194 195 template<typename _Tp, typename _Up> 196 concept __adl_swap 197 = (std::__detail::__class_or_enum<remove_reference_t<_Tp>> 198 || std::__detail::__class_or_enum<remove_reference_t<_Up>>) 199 && requires(_Tp&& __t, _Up&& __u) { 200 swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); 201 }; 202 203 struct _Swap 204 { 205 private: 206 template<typename _Tp, typename _Up> 207 static constexpr bool 208 _S_noexcept() 209 { 210 if constexpr (__adl_swap<_Tp, _Up>) 211 return noexcept(swap(std::declval<_Tp>(), std::declval<_Up>())); 212 else 213 return is_nothrow_move_constructible_v<remove_reference_t<_Tp>> 214 && is_nothrow_move_assignable_v<remove_reference_t<_Tp>>; 215 } 216 217 public: 218 template<typename _Tp, typename _Up> 219 requires __adl_swap<_Tp, _Up> 220 || (same_as<_Tp, _Up> && is_lvalue_reference_v<_Tp> 221 && move_constructible<remove_reference_t<_Tp>> 222 && assignable_from<_Tp, remove_reference_t<_Tp>>) 223 constexpr void 224 operator()(_Tp&& __t, _Up&& __u) const 225 noexcept(_S_noexcept<_Tp, _Up>()) 226 { 227 if constexpr (__adl_swap<_Tp, _Up>) 228 swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); 229 else 230 { 231 auto __tmp = static_cast<remove_reference_t<_Tp>&&>(__t); 232 __t = static_cast<remove_reference_t<_Tp>&&>(__u); 233 __u = static_cast<remove_reference_t<_Tp>&&>(__tmp); 234 } 235 } 236 237 template<typename _Tp, typename _Up, size_t _Num> 238 requires requires(const _Swap& __swap, _Tp& __e1, _Up& __e2) { 239 __swap(__e1, __e2); 240 } 241 constexpr void 242 operator()(_Tp (&__e1)[_Num], _Up (&__e2)[_Num]) const 243 noexcept(noexcept(std::declval<const _Swap&>()(*__e1, *__e2))) 244 { 245 for (size_t __n = 0; __n < _Num; ++__n) 246 (*this)(__e1[__n], __e2[__n]); 247 } 248 }; 249 } // namespace __swap 250 /// @endcond 251 252 inline namespace _Cpo { 253 inline constexpr __swap::_Swap swap{}; 254 } 255 } // namespace ranges 256 257 template<typename _Tp> 258 concept swappable 259 = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); }; 260 261 template<typename _Tp, typename _Up> 262 concept swappable_with = common_reference_with<_Tp, _Up> 263 && requires(_Tp&& __t, _Up&& __u) { 264 ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Tp&&>(__t)); 265 ranges::swap(static_cast<_Up&&>(__u), static_cast<_Up&&>(__u)); 266 ranges::swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); 267 ranges::swap(static_cast<_Up&&>(__u), static_cast<_Tp&&>(__t)); 268 }; 269 270 // [concepts.object], Object concepts 271 272 template<typename _Tp> 273 concept movable = is_object_v<_Tp> && move_constructible<_Tp> 274 && assignable_from<_Tp&, _Tp> && swappable<_Tp>; 275 276 template<typename _Tp> 277 concept copyable = copy_constructible<_Tp> && movable<_Tp> 278 && assignable_from<_Tp&, _Tp&> && assignable_from<_Tp&, const _Tp&> 279 && assignable_from<_Tp&, const _Tp>; 280 281 template<typename _Tp> 282 concept semiregular = copyable<_Tp> && default_initializable<_Tp>; 283 284 // [concepts.compare], comparison concepts 285 286 // [concept.booleantestable], Boolean testability 287 namespace __detail 288 { 289 template<typename _Tp> 290 concept __boolean_testable_impl = convertible_to<_Tp, bool>; 291 292 template<typename _Tp> 293 concept __boolean_testable 294 = __boolean_testable_impl<_Tp> 295 && requires(_Tp&& __t) 296 { { !static_cast<_Tp&&>(__t) } -> __boolean_testable_impl; }; 297 } // namespace __detail 298 299 // [concept.equalitycomparable], concept equality_comparable 300 301 namespace __detail 302 { 303 template<typename _Tp, typename _Up> 304 concept __weakly_eq_cmp_with 305 = requires(__detail::__cref<_Tp> __t, __detail::__cref<_Up> __u) { 306 { __t == __u } -> __boolean_testable; 307 { __t != __u } -> __boolean_testable; 308 { __u == __t } -> __boolean_testable; 309 { __u != __t } -> __boolean_testable; 310 }; 311 } // namespace __detail 312 313 template<typename _Tp> 314 concept equality_comparable = __detail::__weakly_eq_cmp_with<_Tp, _Tp>; 315 316 template<typename _Tp, typename _Up> 317 concept equality_comparable_with 318 = equality_comparable<_Tp> && equality_comparable<_Up> 319 && common_reference_with<__detail::__cref<_Tp>, __detail::__cref<_Up>> 320 && equality_comparable<common_reference_t<__detail::__cref<_Tp>, 321 __detail::__cref<_Up>>> 322 && __detail::__weakly_eq_cmp_with<_Tp, _Up>; 323 324 namespace __detail 325 { 326 template<typename _Tp, typename _Up> 327 concept __partially_ordered_with 328 = requires(const remove_reference_t<_Tp>& __t, 329 const remove_reference_t<_Up>& __u) { 330 { __t < __u } -> __boolean_testable; 331 { __t > __u } -> __boolean_testable; 332 { __t <= __u } -> __boolean_testable; 333 { __t >= __u } -> __boolean_testable; 334 { __u < __t } -> __boolean_testable; 335 { __u > __t } -> __boolean_testable; 336 { __u <= __t } -> __boolean_testable; 337 { __u >= __t } -> __boolean_testable; 338 }; 339 } // namespace __detail 340 341 // [concept.totallyordered], concept totally_ordered 342 template<typename _Tp> 343 concept totally_ordered 344 = equality_comparable<_Tp> 345 && __detail::__partially_ordered_with<_Tp, _Tp>; 346 347 template<typename _Tp, typename _Up> 348 concept totally_ordered_with 349 = totally_ordered<_Tp> && totally_ordered<_Up> 350 && equality_comparable_with<_Tp, _Up> 351 && totally_ordered<common_reference_t<__detail::__cref<_Tp>, 352 __detail::__cref<_Up>>> 353 && __detail::__partially_ordered_with<_Tp, _Up>; 354 355 template<typename _Tp> 356 concept regular = semiregular<_Tp> && equality_comparable<_Tp>; 357 358 // [concepts.callable], callable concepts 359 360 /// [concept.invocable], concept invocable 361 template<typename _Fn, typename... _Args> 362 concept invocable = is_invocable_v<_Fn, _Args...>; 363 364 /// [concept.regularinvocable], concept regular_invocable 365 template<typename _Fn, typename... _Args> 366 concept regular_invocable = invocable<_Fn, _Args...>; 367 368 /// [concept.predicate], concept predicate 369 template<typename _Fn, typename... _Args> 370 concept predicate = regular_invocable<_Fn, _Args...> 371 && __detail::__boolean_testable<invoke_result_t<_Fn, _Args...>>; 372 373 /// [concept.relation], concept relation 374 template<typename _Rel, typename _Tp, typename _Up> 375 concept relation 376 = predicate<_Rel, _Tp, _Tp> && predicate<_Rel, _Up, _Up> 377 && predicate<_Rel, _Tp, _Up> && predicate<_Rel, _Up, _Tp>; 378 379 /// [concept.equiv], concept equivalence_relation 380 template<typename _Rel, typename _Tp, typename _Up> 381 concept equivalence_relation = relation<_Rel, _Tp, _Up>; 382 383 /// [concept.strictweakorder], concept strict_weak_order 384 template<typename _Rel, typename _Tp, typename _Up> 385 concept strict_weak_order = relation<_Rel, _Tp, _Up>; 386 387 namespace __detail 388 { 389 // operator<=> are automatically reversed, so we need to consider 390 // both directions if types are different. 391 template<typename _Tp, typename _Up> 392 concept __not_overloaded_spaceship 393 = ! requires(_Tp&& __t, _Up&& __u) 394 { operator<=>(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); } 395 && ! requires(_Tp&& __t, _Up&& __u) 396 { static_cast<_Tp&&>(__t).operator<=>(static_cast<_Up&&>(__u)); } 397 && (is_same_v<_Tp, _Up> 398 || (! requires(_Tp&& __t, _Up&& __u) 399 { operator<=>(static_cast<_Up&&>(__u), static_cast<_Tp&&>(__t)); } 400 && ! requires(_Tp&& __t, _Up&& __u) 401 { static_cast<_Up&&>(__u).operator<=>(static_cast<_Tp&&>(__t)); })); 402 } 403 _GLIBCXX_END_NAMESPACE_VERSION 404 } // namespace 405 #endif // __cpp_lib_concepts 406 407 #endif /* _GLIBCXX_CONCEPTS */
