1 // Allocator traits -*- C++ -*- 2 3 // Copyright (C) 2011-2018 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 bits/alloc_traits.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{memory} 28 */ 29 30 #ifndef _ALLOC_TRAITS_H 31 #define _ALLOC_TRAITS_H 1 32 33 #if __cplusplus >= 201103L 34 35 #include <bits/memoryfwd.h> 36 #include <bits/ptr_traits.h> 37 #include <ext/numeric_traits.h> 38 39 #define __cpp_lib_allocator_traits_is_always_equal 201411 40 41 namespace std _GLIBCXX_VISIBILITY(default) 42 { 43 _GLIBCXX_BEGIN_NAMESPACE_VERSION 44 45 struct __allocator_traits_base 46 { 47 template<typename _Tp, typename _Up, typename = void> 48 struct __rebind : __replace_first_arg<_Tp, _Up> { }; 49 50 template<typename _Tp, typename _Up> 51 struct __rebind<_Tp, _Up, 52 __void_t<typename _Tp::template rebind<_Up>::other>> 53 { using type = typename _Tp::template rebind<_Up>::other; }; 54 55 protected: 56 template<typename _Tp> 57 using __pointer = typename _Tp::pointer; 58 template<typename _Tp> 59 using __c_pointer = typename _Tp::const_pointer; 60 template<typename _Tp> 61 using __v_pointer = typename _Tp::void_pointer; 62 template<typename _Tp> 63 using __cv_pointer = typename _Tp::const_void_pointer; 64 template<typename _Tp> 65 using __pocca = typename _Tp::propagate_on_container_copy_assignment; 66 template<typename _Tp> 67 using __pocma = typename _Tp::propagate_on_container_move_assignment; 68 template<typename _Tp> 69 using __pocs = typename _Tp::propagate_on_container_swap; 70 template<typename _Tp> 71 using __equal = typename _Tp::is_always_equal; 72 }; 73 74 template<typename _Alloc, typename _Up> 75 using __alloc_rebind 76 = typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type; 77 78 /** 79 * @brief Uniform interface to all allocator types. 80 * @ingroup allocators 81 */ 82 template<typename _Alloc> 83 struct allocator_traits : __allocator_traits_base 84 { 85 /// The allocator type 86 typedef _Alloc allocator_type; 87 /// The allocated type 88 typedef typename _Alloc::value_type value_type; 89 90 /** 91 * @brief The allocator's pointer type. 92 * 93 * @c Alloc::pointer if that type exists, otherwise @c value_type* 94 */ 95 using pointer = __detected_or_t<value_type*, __pointer, _Alloc>; 96 97 private: 98 // Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp> 99 template<template<typename> class _Func, typename _Tp, typename = void> 100 struct _Ptr 101 { 102 using type = typename pointer_traits<pointer>::template rebind<_Tp>; 103 }; 104 105 template<template<typename> class _Func, typename _Tp> 106 struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>> 107 { 108 using type = _Func<_Alloc>; 109 }; 110 111 // Select _A2::difference_type or pointer_traits<_Ptr>::difference_type 112 template<typename _A2, typename _PtrT, typename = void> 113 struct _Diff 114 { using type = typename pointer_traits<_PtrT>::difference_type; }; 115 116 template<typename _A2, typename _PtrT> 117 struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>> 118 { using type = typename _A2::difference_type; }; 119 120 // Select _A2::size_type or make_unsigned<_DiffT>::type 121 template<typename _A2, typename _DiffT, typename = void> 122 struct _Size : make_unsigned<_DiffT> { }; 123 124 template<typename _A2, typename _DiffT> 125 struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>> 126 { using type = typename _A2::size_type; }; 127 128 public: 129 /** 130 * @brief The allocator's const pointer type. 131 * 132 * @c Alloc::const_pointer if that type exists, otherwise 133 * <tt> pointer_traits<pointer>::rebind<const value_type> </tt> 134 */ 135 using const_pointer = typename _Ptr<__c_pointer, const value_type>::type; 136 137 /** 138 * @brief The allocator's void pointer type. 139 * 140 * @c Alloc::void_pointer if that type exists, otherwise 141 * <tt> pointer_traits<pointer>::rebind<void> </tt> 142 */ 143 using void_pointer = typename _Ptr<__v_pointer, void>::type; 144 145 /** 146 * @brief The allocator's const void pointer type. 147 * 148 * @c Alloc::const_void_pointer if that type exists, otherwise 149 * <tt> pointer_traits<pointer>::rebind<const void> </tt> 150 */ 151 using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type; 152 153 /** 154 * @brief The allocator's difference type 155 * 156 * @c Alloc::difference_type if that type exists, otherwise 157 * <tt> pointer_traits<pointer>::difference_type </tt> 158 */ 159 using difference_type = typename _Diff<_Alloc, pointer>::type; 160 161 /** 162 * @brief The allocator's size type 163 * 164 * @c Alloc::size_type if that type exists, otherwise 165 * <tt> make_unsigned<difference_type>::type </tt> 166 */ 167 using size_type = typename _Size<_Alloc, difference_type>::type; 168 169 /** 170 * @brief How the allocator is propagated on copy assignment 171 * 172 * @c Alloc::propagate_on_container_copy_assignment if that type exists, 173 * otherwise @c false_type 174 */ 175 using propagate_on_container_copy_assignment 176 = __detected_or_t<false_type, __pocca, _Alloc>; 177 178 /** 179 * @brief How the allocator is propagated on move assignment 180 * 181 * @c Alloc::propagate_on_container_move_assignment if that type exists, 182 * otherwise @c false_type 183 */ 184 using propagate_on_container_move_assignment 185 = __detected_or_t<false_type, __pocma, _Alloc>; 186 187 /** 188 * @brief How the allocator is propagated on swap 189 * 190 * @c Alloc::propagate_on_container_swap if that type exists, 191 * otherwise @c false_type 192 */ 193 using propagate_on_container_swap 194 = __detected_or_t<false_type, __pocs, _Alloc>; 195 196 /** 197 * @brief Whether all instances of the allocator type compare equal. 198 * 199 * @c Alloc::is_always_equal if that type exists, 200 * otherwise @c is_empty<Alloc>::type 201 */ 202 using is_always_equal 203 = __detected_or_t<typename is_empty<_Alloc>::type, __equal, _Alloc>; 204 205 template<typename _Tp> 206 using rebind_alloc = __alloc_rebind<_Alloc, _Tp>; 207 template<typename _Tp> 208 using rebind_traits = allocator_traits<rebind_alloc<_Tp>>; 209 210 private: 211 template<typename _Alloc2> 212 static auto 213 _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int) 214 -> decltype(__a.allocate(__n, __hint)) 215 { return __a.allocate(__n, __hint); } 216 217 template<typename _Alloc2> 218 static pointer 219 _S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...) 220 { return __a.allocate(__n); } 221 222 template<typename _Tp, typename... _Args> 223 struct __construct_helper 224 { 225 template<typename _Alloc2, 226 typename = decltype(std::declval<_Alloc2*>()->construct( 227 std::declval<_Tp*>(), std::declval<_Args>()...))> 228 static true_type __test(int); 229 230 template<typename> 231 static false_type __test(...); 232 233 using type = decltype(__test<_Alloc>(0)); 234 }; 235 236 template<typename _Tp, typename... _Args> 237 using __has_construct 238 = typename __construct_helper<_Tp, _Args...>::type; 239 240 template<typename _Tp, typename... _Args> 241 static _Require<__has_construct<_Tp, _Args...>> 242 _S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args) 243 { __a.construct(__p, std::forward<_Args>(__args)...); } 244 245 template<typename _Tp, typename... _Args> 246 static 247 _Require<__and_<__not_<__has_construct<_Tp, _Args...>>, 248 is_constructible<_Tp, _Args...>>> 249 _S_construct(_Alloc&, _Tp* __p, _Args&&... __args) 250 { ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); } 251 252 template<typename _Alloc2, typename _Tp> 253 static auto 254 _S_destroy(_Alloc2& __a, _Tp* __p, int) 255 -> decltype(__a.destroy(__p)) 256 { __a.destroy(__p); } 257 258 template<typename _Alloc2, typename _Tp> 259 static void 260 _S_destroy(_Alloc2&, _Tp* __p, ...) 261 { __p->~_Tp(); } 262 263 template<typename _Alloc2> 264 static auto 265 _S_max_size(_Alloc2& __a, int) 266 -> decltype(__a.max_size()) 267 { return __a.max_size(); } 268 269 template<typename _Alloc2> 270 static size_type 271 _S_max_size(_Alloc2&, ...) 272 { 273 // _GLIBCXX_RESOLVE_LIB_DEFECTS 274 // 2466. allocator_traits::max_size() default behavior is incorrect 275 return __gnu_cxx::__numeric_traits<size_type>::__max 276 / sizeof(value_type); 277 } 278 279 template<typename _Alloc2> 280 static auto 281 _S_select(_Alloc2& __a, int) 282 -> decltype(__a.select_on_container_copy_construction()) 283 { return __a.select_on_container_copy_construction(); } 284 285 template<typename _Alloc2> 286 static _Alloc2 287 _S_select(_Alloc2& __a, ...) 288 { return __a; } 289 290 public: 291 292 /** 293 * @brief Allocate memory. 294 * @param __a An allocator. 295 * @param __n The number of objects to allocate space for. 296 * 297 * Calls @c a.allocate(n) 298 */ 299 static pointer 300 allocate(_Alloc& __a, size_type __n) 301 { return __a.allocate(__n); } 302 303 /** 304 * @brief Allocate memory. 305 * @param __a An allocator. 306 * @param __n The number of objects to allocate space for. 307 * @param __hint Aid to locality. 308 * @return Memory of suitable size and alignment for @a n objects 309 * of type @c value_type 310 * 311 * Returns <tt> a.allocate(n, hint) </tt> if that expression is 312 * well-formed, otherwise returns @c a.allocate(n) 313 */ 314 static pointer 315 allocate(_Alloc& __a, size_type __n, const_void_pointer __hint) 316 { return _S_allocate(__a, __n, __hint, 0); } 317 318 /** 319 * @brief Deallocate memory. 320 * @param __a An allocator. 321 * @param __p Pointer to the memory to deallocate. 322 * @param __n The number of objects space was allocated for. 323 * 324 * Calls <tt> a.deallocate(p, n) </tt> 325 */ 326 static void 327 deallocate(_Alloc& __a, pointer __p, size_type __n) 328 { __a.deallocate(__p, __n); } 329 330 /** 331 * @brief Construct an object of type @a _Tp 332 * @param __a An allocator. 333 * @param __p Pointer to memory of suitable size and alignment for Tp 334 * @param __args Constructor arguments. 335 * 336 * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt> 337 * if that expression is well-formed, otherwise uses placement-new 338 * to construct an object of type @a _Tp at location @a __p from the 339 * arguments @a __args... 340 */ 341 template<typename _Tp, typename... _Args> 342 static auto construct(_Alloc& __a, _Tp* __p, _Args&&... __args) 343 -> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...)) 344 { _S_construct(__a, __p, std::forward<_Args>(__args)...); } 345 346 /** 347 * @brief Destroy an object of type @a _Tp 348 * @param __a An allocator. 349 * @param __p Pointer to the object to destroy 350 * 351 * Calls @c __a.destroy(__p) if that expression is well-formed, 352 * otherwise calls @c __p->~_Tp() 353 */ 354 template<typename _Tp> 355 static void destroy(_Alloc& __a, _Tp* __p) 356 { _S_destroy(__a, __p, 0); } 357 358 /** 359 * @brief The maximum supported allocation size 360 * @param __a An allocator. 361 * @return @c __a.max_size() or @c numeric_limits<size_type>::max() 362 * 363 * Returns @c __a.max_size() if that expression is well-formed, 364 * otherwise returns @c numeric_limits<size_type>::max() 365 */ 366 static size_type max_size(const _Alloc& __a) noexcept 367 { return _S_max_size(__a, 0); } 368 369 /** 370 * @brief Obtain an allocator to use when copying a container. 371 * @param __rhs An allocator. 372 * @return @c __rhs.select_on_container_copy_construction() or @a __rhs 373 * 374 * Returns @c __rhs.select_on_container_copy_construction() if that 375 * expression is well-formed, otherwise returns @a __rhs 376 */ 377 static _Alloc 378 select_on_container_copy_construction(const _Alloc& __rhs) 379 { return _S_select(__rhs, 0); } 380 }; 381 382 /// Partial specialization for std::allocator. 383 template<typename _Tp> 384 struct allocator_traits<allocator<_Tp>> 385 { 386 /// The allocator type 387 using allocator_type = allocator<_Tp>; 388 /// The allocated type 389 using value_type = _Tp; 390 391 /// The allocator's pointer type. 392 using pointer = _Tp*; 393 394 /// The allocator's const pointer type. 395 using const_pointer = const _Tp*; 396 397 /// The allocator's void pointer type. 398 using void_pointer = void*; 399 400 /// The allocator's const void pointer type. 401 using const_void_pointer = const void*; 402 403 /// The allocator's difference type 404 using difference_type = std::ptrdiff_t; 405 406 /// The allocator's size type 407 using size_type = std::size_t; 408 409 /// How the allocator is propagated on copy assignment 410 using propagate_on_container_copy_assignment = false_type; 411 412 /// How the allocator is propagated on move assignment 413 using propagate_on_container_move_assignment = true_type; 414 415 /// How the allocator is propagated on swap 416 using propagate_on_container_swap = false_type; 417 418 /// Whether all instances of the allocator type compare equal. 419 using is_always_equal = true_type; 420 421 template<typename _Up> 422 using rebind_alloc = allocator<_Up>; 423 424 template<typename _Up> 425 using rebind_traits = allocator_traits<allocator<_Up>>; 426 427 /** 428 * @brief Allocate memory. 429 * @param __a An allocator. 430 * @param __n The number of objects to allocate space for. 431 * 432 * Calls @c a.allocate(n) 433 */ 434 static pointer 435 allocate(allocator_type& __a, size_type __n) 436 { return __a.allocate(__n); } 437 438 /** 439 * @brief Allocate memory. 440 * @param __a An allocator. 441 * @param __n The number of objects to allocate space for. 442 * @param __hint Aid to locality. 443 * @return Memory of suitable size and alignment for @a n objects 444 * of type @c value_type 445 * 446 * Returns <tt> a.allocate(n, hint) </tt> 447 */ 448 static pointer 449 allocate(allocator_type& __a, size_type __n, const_void_pointer __hint) 450 { return __a.allocate(__n, __hint); } 451 452 /** 453 * @brief Deallocate memory. 454 * @param __a An allocator. 455 * @param __p Pointer to the memory to deallocate. 456 * @param __n The number of objects space was allocated for. 457 * 458 * Calls <tt> a.deallocate(p, n) </tt> 459 */ 460 static void 461 deallocate(allocator_type& __a, pointer __p, size_type __n) 462 { __a.deallocate(__p, __n); } 463 464 /** 465 * @brief Construct an object of type @a _Up 466 * @param __a An allocator. 467 * @param __p Pointer to memory of suitable size and alignment for Tp 468 * @param __args Constructor arguments. 469 * 470 * Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt> 471 */ 472 template<typename _Up, typename... _Args> 473 static void 474 construct(allocator_type& __a, _Up* __p, _Args&&... __args) 475 { __a.construct(__p, std::forward<_Args>(__args)...); } 476 477 /** 478 * @brief Destroy an object of type @a _Up 479 * @param __a An allocator. 480 * @param __p Pointer to the object to destroy 481 * 482 * Calls @c __a.destroy(__p). 483 */ 484 template<typename _Up> 485 static void 486 destroy(allocator_type& __a, _Up* __p) 487 { __a.destroy(__p); } 488 489 /** 490 * @brief The maximum supported allocation size 491 * @param __a An allocator. 492 * @return @c __a.max_size() 493 */ 494 static size_type 495 max_size(const allocator_type& __a) noexcept 496 { return __a.max_size(); } 497 498 /** 499 * @brief Obtain an allocator to use when copying a container. 500 * @param __rhs An allocator. 501 * @return @c __rhs 502 */ 503 static allocator_type 504 select_on_container_copy_construction(const allocator_type& __rhs) 505 { return __rhs; } 506 }; 507 508 509 template<typename _Alloc> 510 inline void 511 __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type) 512 { __one = __two; } 513 514 template<typename _Alloc> 515 inline void 516 __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type) 517 { } 518 519 template<typename _Alloc> 520 inline void __alloc_on_copy(_Alloc& __one, const _Alloc& __two) 521 { 522 typedef allocator_traits<_Alloc> __traits; 523 typedef typename __traits::propagate_on_container_copy_assignment __pocca; 524 __do_alloc_on_copy(__one, __two, __pocca()); 525 } 526 527 template<typename _Alloc> 528 inline _Alloc __alloc_on_copy(const _Alloc& __a) 529 { 530 typedef allocator_traits<_Alloc> __traits; 531 return __traits::select_on_container_copy_construction(__a); 532 } 533 534 template<typename _Alloc> 535 inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type) 536 { __one = std::move(__two); } 537 538 template<typename _Alloc> 539 inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type) 540 { } 541 542 template<typename _Alloc> 543 inline void __alloc_on_move(_Alloc& __one, _Alloc& __two) 544 { 545 typedef allocator_traits<_Alloc> __traits; 546 typedef typename __traits::propagate_on_container_move_assignment __pocma; 547 __do_alloc_on_move(__one, __two, __pocma()); 548 } 549 550 template<typename _Alloc> 551 inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type) 552 { 553 using std::swap; 554 swap(__one, __two); 555 } 556 557 template<typename _Alloc> 558 inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type) 559 { } 560 561 template<typename _Alloc> 562 inline void __alloc_on_swap(_Alloc& __one, _Alloc& __two) 563 { 564 typedef allocator_traits<_Alloc> __traits; 565 typedef typename __traits::propagate_on_container_swap __pocs; 566 __do_alloc_on_swap(__one, __two, __pocs()); 567 } 568 569 template<typename _Alloc> 570 class __is_copy_insertable_impl 571 { 572 typedef allocator_traits<_Alloc> _Traits; 573 574 template<typename _Up, typename 575 = decltype(_Traits::construct(std::declval<_Alloc&>(), 576 std::declval<_Up*>(), 577 std::declval<const _Up&>()))> 578 static true_type 579 _M_select(int); 580 581 template<typename _Up> 582 static false_type 583 _M_select(...); 584 585 public: 586 typedef decltype(_M_select<typename _Alloc::value_type>(0)) type; 587 }; 588 589 // true if _Alloc::value_type is CopyInsertable into containers using _Alloc 590 template<typename _Alloc> 591 struct __is_copy_insertable 592 : __is_copy_insertable_impl<_Alloc>::type 593 { }; 594 595 // std::allocator<_Tp> just requires CopyConstructible 596 template<typename _Tp> 597 struct __is_copy_insertable<allocator<_Tp>> 598 : is_copy_constructible<_Tp> 599 { }; 600 601 // Trait to detect Allocator-like types. 602 template<typename _Alloc, typename = void> 603 struct __is_allocator : false_type { }; 604 605 template<typename _Alloc> 606 struct __is_allocator<_Alloc, 607 __void_t<typename _Alloc::value_type, 608 decltype(std::declval<_Alloc&>().allocate(size_t{}))>> 609 : true_type { }; 610 611 template<typename _Alloc> 612 using _RequireAllocator 613 = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type; 614 615 _GLIBCXX_END_NAMESPACE_VERSION 616 } // namespace std 617 #endif // C++11 618 #endif // _ALLOC_TRAITS_H 619