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The C and C++ Include Header Files
/usr/include/c++/13/bits/memory_resource.h
$ cat -n /usr/include/c++/13/bits/memory_resource.h 1 // <memory_resource> -*- C++ -*- 2 3 // Copyright (C) 2018-2023 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/bits/memory_resource.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{memory_resource} 28 */ 29 30 #ifndef _GLIBCXX_MEMORY_RESOURCE_H 31 #define _GLIBCXX_MEMORY_RESOURCE_H 1 32 33 #pragma GCC system_header 34 35 #if __cplusplus >= 201703L 36 37 #include <new> // operator new(size_t, void*) 38 #include <cstddef> // size_t, max_align_t, byte 39 #include <bits/functexcept.h> // __throw_bad_array_new_length 40 #include <bits/uses_allocator.h> // allocator_arg_t, __use_alloc 41 #include <bits/uses_allocator_args.h> // uninitialized_construct_using_alloc 42 #include <ext/numeric_traits.h> // __int_traits 43 #include <debug/assertions.h> 44 45 #if ! __cpp_lib_make_obj_using_allocator 46 # include <bits/utility.h> // index_sequence 47 # include <tuple> // tuple, forward_as_tuple 48 #endif 49 50 namespace std _GLIBCXX_VISIBILITY(default) 51 { 52 _GLIBCXX_BEGIN_NAMESPACE_VERSION 53 namespace pmr 54 { 55 /// Class memory_resource 56 /** 57 * @ingroup pmr 58 * @headerfile memory_resource 59 * @since C++17 60 */ 61 class memory_resource 62 { 63 static constexpr size_t _S_max_align = alignof(max_align_t); 64 65 public: 66 memory_resource() = default; 67 memory_resource(const memory_resource&) = default; 68 virtual ~memory_resource(); // key function 69 70 memory_resource& operator=(const memory_resource&) = default; 71 72 [[nodiscard]] 73 void* 74 allocate(size_t __bytes, size_t __alignment = _S_max_align) 75 __attribute__((__returns_nonnull__,__alloc_size__(2),__alloc_align__(3))) 76 { return ::operator new(__bytes, do_allocate(__bytes, __alignment)); } 77 78 void 79 deallocate(void* __p, size_t __bytes, size_t __alignment = _S_max_align) 80 __attribute__((__nonnull__)) 81 { return do_deallocate(__p, __bytes, __alignment); } 82 83 [[nodiscard]] 84 bool 85 is_equal(const memory_resource& __other) const noexcept 86 { return do_is_equal(__other); } 87 88 private: 89 virtual void* 90 do_allocate(size_t __bytes, size_t __alignment) = 0; 91 92 virtual void 93 do_deallocate(void* __p, size_t __bytes, size_t __alignment) = 0; 94 95 virtual bool 96 do_is_equal(const memory_resource& __other) const noexcept = 0; 97 }; 98 99 [[nodiscard]] 100 inline bool 101 operator==(const memory_resource& __a, const memory_resource& __b) noexcept 102 { return &__a == &__b || __a.is_equal(__b); } 103 104 #if __cpp_impl_three_way_comparison < 201907L 105 [[nodiscard]] 106 inline bool 107 operator!=(const memory_resource& __a, const memory_resource& __b) noexcept 108 { return !(__a == __b); } 109 #endif 110 111 // C++17 23.12.3 Class template polymorphic_allocator 112 113 /// Class template polymorphic_allocator 114 /** 115 * @ingroup pmr 116 * @headerfile memory_resource 117 * @since C++17 118 */ 119 template<typename _Tp> 120 class polymorphic_allocator 121 { 122 // _GLIBCXX_RESOLVE_LIB_DEFECTS 123 // 2975. Missing case for pair construction in polymorphic allocators 124 template<typename _Up> 125 struct __not_pair { using type = void; }; 126 127 template<typename _Up1, typename _Up2> 128 struct __not_pair<pair<_Up1, _Up2>> { }; 129 130 public: 131 using value_type = _Tp; 132 133 polymorphic_allocator() noexcept 134 { 135 extern memory_resource* get_default_resource() noexcept 136 __attribute__((__returns_nonnull__)); 137 _M_resource = get_default_resource(); 138 } 139 140 polymorphic_allocator(memory_resource* __r) noexcept 141 __attribute__((__nonnull__)) 142 : _M_resource(__r) 143 { _GLIBCXX_DEBUG_ASSERT(__r); } 144 145 polymorphic_allocator(const polymorphic_allocator& __other) = default; 146 147 template<typename _Up> 148 polymorphic_allocator(const polymorphic_allocator<_Up>& __x) noexcept 149 : _M_resource(__x.resource()) 150 { } 151 152 polymorphic_allocator& 153 operator=(const polymorphic_allocator&) = delete; 154 155 [[nodiscard]] 156 _Tp* 157 allocate(size_t __n) 158 __attribute__((__returns_nonnull__)) 159 { 160 if ((__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Tp)) < __n) 161 std::__throw_bad_array_new_length(); 162 return static_cast<_Tp*>(_M_resource->allocate(__n * sizeof(_Tp), 163 alignof(_Tp))); 164 } 165 166 void 167 deallocate(_Tp* __p, size_t __n) noexcept 168 __attribute__((__nonnull__)) 169 { _M_resource->deallocate(__p, __n * sizeof(_Tp), alignof(_Tp)); } 170 171 #if __cplusplus > 201703L 172 [[nodiscard]] void* 173 allocate_bytes(size_t __nbytes, 174 size_t __alignment = alignof(max_align_t)) 175 { return _M_resource->allocate(__nbytes, __alignment); } 176 177 void 178 deallocate_bytes(void* __p, size_t __nbytes, 179 size_t __alignment = alignof(max_align_t)) 180 { _M_resource->deallocate(__p, __nbytes, __alignment); } 181 182 template<typename _Up> 183 [[nodiscard]] _Up* 184 allocate_object(size_t __n = 1) 185 { 186 if ((__gnu_cxx::__int_traits<size_t>::__max / sizeof(_Up)) < __n) 187 std::__throw_bad_array_new_length(); 188 return static_cast<_Up*>(allocate_bytes(__n * sizeof(_Up), 189 alignof(_Up))); 190 } 191 192 template<typename _Up> 193 void 194 deallocate_object(_Up* __p, size_t __n = 1) 195 { deallocate_bytes(__p, __n * sizeof(_Up), alignof(_Up)); } 196 197 template<typename _Up, typename... _CtorArgs> 198 [[nodiscard]] _Up* 199 new_object(_CtorArgs&&... __ctor_args) 200 { 201 _Up* __p = allocate_object<_Up>(); 202 __try 203 { 204 construct(__p, std::forward<_CtorArgs>(__ctor_args)...); 205 } 206 __catch (...) 207 { 208 deallocate_object(__p); 209 __throw_exception_again; 210 } 211 return __p; 212 } 213 214 template<typename _Up> 215 void 216 delete_object(_Up* __p) 217 { 218 __p->~_Up(); 219 deallocate_object(__p); 220 } 221 #endif // C++2a 222 223 #if ! __cpp_lib_make_obj_using_allocator 224 template<typename _Tp1, typename... _Args> 225 __attribute__((__nonnull__)) 226 typename __not_pair<_Tp1>::type 227 construct(_Tp1* __p, _Args&&... __args) 228 { 229 // _GLIBCXX_RESOLVE_LIB_DEFECTS 230 // 2969. polymorphic_allocator::construct() shouldn't pass resource() 231 using __use_tag 232 = std::__uses_alloc_t<_Tp1, polymorphic_allocator, _Args...>; 233 if constexpr (is_base_of_v<__uses_alloc0, __use_tag>) 234 ::new(__p) _Tp1(std::forward<_Args>(__args)...); 235 else if constexpr (is_base_of_v<__uses_alloc1_, __use_tag>) 236 ::new(__p) _Tp1(allocator_arg, *this, 237 std::forward<_Args>(__args)...); 238 else 239 ::new(__p) _Tp1(std::forward<_Args>(__args)..., *this); 240 } 241 242 template<typename _Tp1, typename _Tp2, 243 typename... _Args1, typename... _Args2> 244 __attribute__((__nonnull__)) 245 void 246 construct(pair<_Tp1, _Tp2>* __p, piecewise_construct_t, 247 tuple<_Args1...> __x, tuple<_Args2...> __y) 248 { 249 auto __x_tag = 250 __use_alloc<_Tp1, polymorphic_allocator, _Args1...>(*this); 251 auto __y_tag = 252 __use_alloc<_Tp2, polymorphic_allocator, _Args2...>(*this); 253 index_sequence_for<_Args1...> __x_i; 254 index_sequence_for<_Args2...> __y_i; 255 256 ::new(__p) pair<_Tp1, _Tp2>(piecewise_construct, 257 _S_construct_p(__x_tag, __x_i, __x), 258 _S_construct_p(__y_tag, __y_i, __y)); 259 } 260 261 template<typename _Tp1, typename _Tp2> 262 __attribute__((__nonnull__)) 263 void 264 construct(pair<_Tp1, _Tp2>* __p) 265 { this->construct(__p, piecewise_construct, tuple<>(), tuple<>()); } 266 267 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 268 __attribute__((__nonnull__)) 269 void 270 construct(pair<_Tp1, _Tp2>* __p, _Up&& __x, _Vp&& __y) 271 { 272 this->construct(__p, piecewise_construct, 273 std::forward_as_tuple(std::forward<_Up>(__x)), 274 std::forward_as_tuple(std::forward<_Vp>(__y))); 275 } 276 277 template <typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 278 __attribute__((__nonnull__)) 279 void 280 construct(pair<_Tp1, _Tp2>* __p, const std::pair<_Up, _Vp>& __pr) 281 { 282 this->construct(__p, piecewise_construct, 283 std::forward_as_tuple(__pr.first), 284 std::forward_as_tuple(__pr.second)); 285 } 286 287 template<typename _Tp1, typename _Tp2, typename _Up, typename _Vp> 288 __attribute__((__nonnull__)) 289 void 290 construct(pair<_Tp1, _Tp2>* __p, pair<_Up, _Vp>&& __pr) 291 { 292 this->construct(__p, piecewise_construct, 293 std::forward_as_tuple(std::forward<_Up>(__pr.first)), 294 std::forward_as_tuple(std::forward<_Vp>(__pr.second))); 295 } 296 #else // make_obj_using_allocator 297 template<typename _Tp1, typename... _Args> 298 __attribute__((__nonnull__)) 299 void 300 construct(_Tp1* __p, _Args&&... __args) 301 { 302 std::uninitialized_construct_using_allocator(__p, *this, 303 std::forward<_Args>(__args)...); 304 } 305 #endif 306 307 template<typename _Up> 308 _GLIBCXX20_DEPRECATED_SUGGEST("allocator_traits::destroy") 309 __attribute__((__nonnull__)) 310 void 311 destroy(_Up* __p) 312 { __p->~_Up(); } 313 314 polymorphic_allocator 315 select_on_container_copy_construction() const noexcept 316 { return polymorphic_allocator(); } 317 318 memory_resource* 319 resource() const noexcept 320 __attribute__((__returns_nonnull__)) 321 { return _M_resource; } 322 323 // _GLIBCXX_RESOLVE_LIB_DEFECTS 324 // 3683. operator== for polymorphic_allocator cannot deduce template arg 325 [[nodiscard]] 326 friend bool 327 operator==(const polymorphic_allocator& __a, 328 const polymorphic_allocator& __b) noexcept 329 { return *__a.resource() == *__b.resource(); } 330 331 #if __cpp_impl_three_way_comparison < 201907L 332 [[nodiscard]] 333 friend bool 334 operator!=(const polymorphic_allocator& __a, 335 const polymorphic_allocator& __b) noexcept 336 { return !(__a == __b); } 337 #endif 338 339 private: 340 #if ! __cpp_lib_make_obj_using_allocator 341 using __uses_alloc1_ = __uses_alloc1<polymorphic_allocator>; 342 using __uses_alloc2_ = __uses_alloc2<polymorphic_allocator>; 343 344 template<typename _Ind, typename... _Args> 345 static tuple<_Args&&...> 346 _S_construct_p(__uses_alloc0, _Ind, tuple<_Args...>& __t) 347 { return std::move(__t); } 348 349 template<size_t... _Ind, typename... _Args> 350 static tuple<allocator_arg_t, polymorphic_allocator, _Args&&...> 351 _S_construct_p(__uses_alloc1_ __ua, index_sequence<_Ind...>, 352 tuple<_Args...>& __t) 353 { 354 return { 355 allocator_arg, *__ua._M_a, std::get<_Ind>(std::move(__t))... 356 }; 357 } 358 359 template<size_t... _Ind, typename... _Args> 360 static tuple<_Args&&..., polymorphic_allocator> 361 _S_construct_p(__uses_alloc2_ __ua, index_sequence<_Ind...>, 362 tuple<_Args...>& __t) 363 { return { std::get<_Ind>(std::move(__t))..., *__ua._M_a }; } 364 #endif 365 366 memory_resource* _M_resource; 367 }; 368 369 template<typename _Tp1, typename _Tp2> 370 [[nodiscard]] 371 inline bool 372 operator==(const polymorphic_allocator<_Tp1>& __a, 373 const polymorphic_allocator<_Tp2>& __b) noexcept 374 { return *__a.resource() == *__b.resource(); } 375 376 #if __cpp_impl_three_way_comparison < 201907L 377 template<typename _Tp1, typename _Tp2> 378 [[nodiscard]] 379 inline bool 380 operator!=(const polymorphic_allocator<_Tp1>& __a, 381 const polymorphic_allocator<_Tp2>& __b) noexcept 382 { return !(__a == __b); } 383 #endif 384 385 } // namespace pmr 386 387 template<typename _Alloc> struct allocator_traits; 388 389 /// Partial specialization for std::pmr::polymorphic_allocator 390 template<typename _Tp> 391 struct allocator_traits<pmr::polymorphic_allocator<_Tp>> 392 { 393 /// The allocator type 394 using allocator_type = pmr::polymorphic_allocator<_Tp>; 395 396 /// The allocated type 397 using value_type = _Tp; 398 399 /// The allocator's pointer type. 400 using pointer = _Tp*; 401 402 /// The allocator's const pointer type. 403 using const_pointer = const _Tp*; 404 405 /// The allocator's void pointer type. 406 using void_pointer = void*; 407 408 /// The allocator's const void pointer type. 409 using const_void_pointer = const void*; 410 411 /// The allocator's difference type 412 using difference_type = std::ptrdiff_t; 413 414 /// The allocator's size type 415 using size_type = std::size_t; 416 417 /** @{ 418 * A `polymorphic_allocator` does not propagate when a 419 * container is copied, moved, or swapped. 420 */ 421 using propagate_on_container_copy_assignment = false_type; 422 using propagate_on_container_move_assignment = false_type; 423 using propagate_on_container_swap = false_type; 424 425 static allocator_type 426 select_on_container_copy_construction(const allocator_type&) noexcept 427 { return allocator_type(); } 428 /// @} 429 430 /// Whether all instances of the allocator type compare equal. 431 using is_always_equal = false_type; 432 433 template<typename _Up> 434 using rebind_alloc = pmr::polymorphic_allocator<_Up>; 435 436 template<typename _Up> 437 using rebind_traits = allocator_traits<pmr::polymorphic_allocator<_Up>>; 438 439 /** 440 * @brief Allocate memory. 441 * @param __a An allocator. 442 * @param __n The number of objects to allocate space for. 443 * 444 * Calls `a.allocate(n)`. 445 */ 446 [[nodiscard]] static pointer 447 allocate(allocator_type& __a, size_type __n) 448 { return __a.allocate(__n); } 449 450 /** 451 * @brief Allocate memory. 452 * @param __a An allocator. 453 * @param __n The number of objects to allocate space for. 454 * @return Memory of suitable size and alignment for `n` objects 455 * of type `value_type`. 456 * 457 * The third parameter is ignored.. 458 * 459 * Returns `a.allocate(n)`. 460 */ 461 [[nodiscard]] static pointer 462 allocate(allocator_type& __a, size_type __n, const_void_pointer) 463 { return __a.allocate(__n); } 464 465 /** 466 * @brief Deallocate memory. 467 * @param __a An allocator. 468 * @param __p Pointer to the memory to deallocate. 469 * @param __n The number of objects space was allocated for. 470 * 471 * Calls `a.deallocate(p, n)`. 472 */ 473 static void 474 deallocate(allocator_type& __a, pointer __p, size_type __n) 475 { __a.deallocate(__p, __n); } 476 477 /** 478 * @brief Construct an object of type `_Up` 479 * @param __a An allocator. 480 * @param __p Pointer to memory of suitable size and alignment for 481 * an object of type `_Up`. 482 * @param __args Constructor arguments. 483 * 484 * Calls `__a.construct(__p, std::forward<_Args>(__args)...)` 485 * in C++11, C++14 and C++17. Changed in C++20 to call 486 * `std::construct_at(__p, std::forward<_Args>(__args)...)` instead. 487 */ 488 template<typename _Up, typename... _Args> 489 static void 490 construct(allocator_type& __a, _Up* __p, _Args&&... __args) 491 { __a.construct(__p, std::forward<_Args>(__args)...); } 492 493 /** 494 * @brief Destroy an object of type `_Up` 495 * @param __a An allocator. 496 * @param __p Pointer to the object to destroy 497 * 498 * Calls `p->_Up()`. 499 */ 500 template<typename _Up> 501 static _GLIBCXX20_CONSTEXPR void 502 destroy(allocator_type&, _Up* __p) 503 noexcept(is_nothrow_destructible<_Up>::value) 504 { __p->~_Up(); } 505 506 /** 507 * @brief The maximum supported allocation size 508 * @return `numeric_limits<size_t>::max() / sizeof(value_type)` 509 */ 510 static _GLIBCXX20_CONSTEXPR size_type 511 max_size(const allocator_type&) noexcept 512 { return size_t(-1) / sizeof(value_type); } 513 }; 514 515 _GLIBCXX_END_NAMESPACE_VERSION 516 } // namespace std 517 518 #endif // C++17 519 #endif // _GLIBCXX_MEMORY_RESOURCE_H
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