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The C and C++ Include Header Files
/usr/include/c++/13/bits/shared_ptr.h
$ cat -n /usr/include/c++/13/bits/shared_ptr.h 1 // shared_ptr and weak_ptr implementation -*- C++ -*- 2 3 // Copyright (C) 2007-2023 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 // GCC Note: Based on files from version 1.32.0 of the Boost library. 26 27 // shared_count.hpp 28 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. 29 30 // shared_ptr.hpp 31 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes. 32 // Copyright (C) 2001, 2002, 2003 Peter Dimov 33 34 // weak_ptr.hpp 35 // Copyright (C) 2001, 2002, 2003 Peter Dimov 36 37 // enable_shared_from_this.hpp 38 // Copyright (C) 2002 Peter Dimov 39 40 // Distributed under the Boost Software License, Version 1.0. (See 41 // accompanying file LICENSE_1_0.txt or copy at 42 // http://www.boost.org/LICENSE_1_0.txt) 43 44 /** @file 45 * This is an internal header file, included by other library headers. 46 * Do not attempt to use it directly. @headername{memory} 47 */ 48 49 #ifndef _SHARED_PTR_H 50 #define _SHARED_PTR_H 1 51 52 #include <iosfwd> // std::basic_ostream 53 #include <bits/shared_ptr_base.h> 54 55 namespace std _GLIBCXX_VISIBILITY(default) 56 { 57 _GLIBCXX_BEGIN_NAMESPACE_VERSION 58 59 /** 60 * @addtogroup pointer_abstractions 61 * @{ 62 */ 63 64 // 20.7.2.2.11 shared_ptr I/O 65 66 /// Write the stored pointer to an ostream. 67 /// @relates shared_ptr 68 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp> 69 inline std::basic_ostream<_Ch, _Tr>& 70 operator<<(std::basic_ostream<_Ch, _Tr>& __os, 71 const __shared_ptr<_Tp, _Lp>& __p) 72 { 73 __os << __p.get(); 74 return __os; 75 } 76 77 template<typename _Del, typename _Tp, _Lock_policy _Lp> 78 inline _Del* 79 get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept 80 { 81 #if __cpp_rtti 82 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); 83 #else 84 return 0; 85 #endif 86 } 87 88 /// 20.7.2.2.10 shared_ptr get_deleter 89 90 /// If `__p` has a deleter of type `_Del`, return a pointer to it. 91 /// @relates shared_ptr 92 template<typename _Del, typename _Tp> 93 inline _Del* 94 get_deleter(const shared_ptr<_Tp>& __p) noexcept 95 { 96 #if __cpp_rtti 97 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); 98 #else 99 return 0; 100 #endif 101 } 102 103 /// @cond undocumented 104 105 // Constraint for overloads taking non-array types. 106 #if __cpp_concepts && __cpp_lib_type_trait_variable_templates 107 template<typename _Tp> 108 requires (!is_array_v<_Tp>) 109 using _NonArray = _Tp; 110 #else 111 template<typename _Tp> 112 using _NonArray = __enable_if_t<!is_array<_Tp>::value, _Tp>; 113 #endif 114 115 #if __cpp_lib_shared_ptr_arrays >= 201707L 116 // Constraint for overloads taking array types with unknown bound, U[]. 117 #if __cpp_concepts 118 template<typename _Tp> 119 requires is_array_v<_Tp> && (extent_v<_Tp> == 0) 120 using _UnboundedArray = _Tp; 121 #else 122 template<typename _Tp> 123 using _UnboundedArray 124 = __enable_if_t<__is_array_unknown_bounds<_Tp>::value, _Tp>; 125 #endif 126 127 // Constraint for overloads taking array types with known bound, U[N]. 128 #if __cpp_concepts 129 template<typename _Tp> 130 requires (extent_v<_Tp> != 0) 131 using _BoundedArray = _Tp; 132 #else 133 template<typename _Tp> 134 using _BoundedArray 135 = __enable_if_t<__is_array_known_bounds<_Tp>::value, _Tp>; 136 #endif 137 138 #if __cpp_lib_smart_ptr_for_overwrite 139 // Constraint for overloads taking either non-array or bounded array, U[N]. 140 #if __cpp_concepts 141 template<typename _Tp> 142 requires (!is_array_v<_Tp>) || (extent_v<_Tp> != 0) 143 using _NotUnboundedArray = _Tp; 144 #else 145 template<typename _Tp> 146 using _NotUnboundedArray 147 = __enable_if_t<!__is_array_unknown_bounds<_Tp>::value, _Tp>; 148 #endif 149 #endif // smart_ptr_for_overwrite 150 #endif // shared_ptr_arrays 151 152 /// @endcond 153 154 /** 155 * @brief A smart pointer with reference-counted copy semantics. 156 * @headerfile memory 157 * @since C++11 158 * 159 * A `shared_ptr` object is either empty or _owns_ a pointer passed 160 * to the constructor. Copies of a `shared_ptr` share ownership of 161 * the same pointer. When the last `shared_ptr` that owns the pointer 162 * is destroyed or reset, the owned pointer is freed (either by `delete` 163 * or by invoking a custom deleter that was passed to the constructor). 164 * 165 * A `shared_ptr` also stores another pointer, which is usually 166 * (but not always) the same pointer as it owns. The stored pointer 167 * can be retrieved by calling the `get()` member function. 168 * 169 * The equality and relational operators for `shared_ptr` only compare 170 * the stored pointer returned by `get()`, not the owned pointer. 171 * To test whether two `shared_ptr` objects share ownership of the same 172 * pointer see `std::shared_ptr::owner_before` and `std::owner_less`. 173 */ 174 template<typename _Tp> 175 class shared_ptr : public __shared_ptr<_Tp> 176 { 177 template<typename... _Args> 178 using _Constructible = typename enable_if< 179 is_constructible<__shared_ptr<_Tp>, _Args...>::value 180 >::type; 181 182 template<typename _Arg> 183 using _Assignable = typename enable_if< 184 is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& 185 >::type; 186 187 public: 188 189 /// The type pointed to by the stored pointer, remove_extent_t<_Tp> 190 using element_type = typename __shared_ptr<_Tp>::element_type; 191 192 #if __cplusplus >= 201703L 193 # define __cpp_lib_shared_ptr_weak_type 201606L 194 /// The corresponding weak_ptr type for this shared_ptr 195 /// @since C++17 196 using weak_type = weak_ptr<_Tp>; 197 #endif 198 /** 199 * @brief Construct an empty %shared_ptr. 200 * @post use_count()==0 && get()==0 201 */ 202 constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } 203 204 shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor 205 206 /** 207 * @brief Construct a %shared_ptr that owns the pointer @a __p. 208 * @param __p A pointer that is convertible to element_type*. 209 * @post use_count() == 1 && get() == __p 210 * @throw std::bad_alloc, in which case @c delete @a __p is called. 211 */ 212 template<typename _Yp, typename = _Constructible<_Yp*>> 213 explicit 214 shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } 215 216 /** 217 * @brief Construct a %shared_ptr that owns the pointer @a __p 218 * and the deleter @a __d. 219 * @param __p A pointer. 220 * @param __d A deleter. 221 * @post use_count() == 1 && get() == __p 222 * @throw std::bad_alloc, in which case @a __d(__p) is called. 223 * 224 * Requirements: _Deleter's copy constructor and destructor must 225 * not throw 226 * 227 * __shared_ptr will release __p by calling __d(__p) 228 */ 229 template<typename _Yp, typename _Deleter, 230 typename = _Constructible<_Yp*, _Deleter>> 231 shared_ptr(_Yp* __p, _Deleter __d) 232 : __shared_ptr<_Tp>(__p, std::move(__d)) { } 233 234 /** 235 * @brief Construct a %shared_ptr that owns a null pointer 236 * and the deleter @a __d. 237 * @param __p A null pointer constant. 238 * @param __d A deleter. 239 * @post use_count() == 1 && get() == __p 240 * @throw std::bad_alloc, in which case @a __d(__p) is called. 241 * 242 * Requirements: _Deleter's copy constructor and destructor must 243 * not throw 244 * 245 * The last owner will call __d(__p) 246 */ 247 template<typename _Deleter> 248 shared_ptr(nullptr_t __p, _Deleter __d) 249 : __shared_ptr<_Tp>(__p, std::move(__d)) { } 250 251 /** 252 * @brief Construct a %shared_ptr that owns the pointer @a __p 253 * and the deleter @a __d. 254 * @param __p A pointer. 255 * @param __d A deleter. 256 * @param __a An allocator. 257 * @post use_count() == 1 && get() == __p 258 * @throw std::bad_alloc, in which case @a __d(__p) is called. 259 * 260 * Requirements: _Deleter's copy constructor and destructor must 261 * not throw _Alloc's copy constructor and destructor must not 262 * throw. 263 * 264 * __shared_ptr will release __p by calling __d(__p) 265 */ 266 template<typename _Yp, typename _Deleter, typename _Alloc, 267 typename = _Constructible<_Yp*, _Deleter, _Alloc>> 268 shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) 269 : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } 270 271 /** 272 * @brief Construct a %shared_ptr that owns a null pointer 273 * and the deleter @a __d. 274 * @param __p A null pointer constant. 275 * @param __d A deleter. 276 * @param __a An allocator. 277 * @post use_count() == 1 && get() == __p 278 * @throw std::bad_alloc, in which case @a __d(__p) is called. 279 * 280 * Requirements: _Deleter's copy constructor and destructor must 281 * not throw _Alloc's copy constructor and destructor must not 282 * throw. 283 * 284 * The last owner will call __d(__p) 285 */ 286 template<typename _Deleter, typename _Alloc> 287 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 288 : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } 289 290 // Aliasing constructor 291 292 /** 293 * @brief Constructs a `shared_ptr` instance that stores `__p` 294 * and shares ownership with `__r`. 295 * @param __r A `shared_ptr`. 296 * @param __p A pointer that will remain valid while `*__r` is valid. 297 * @post `get() == __p && use_count() == __r.use_count()` 298 * 299 * This can be used to construct a `shared_ptr` to a sub-object 300 * of an object managed by an existing `shared_ptr`. The complete 301 * object will remain valid while any `shared_ptr` owns it, even 302 * if they don't store a pointer to the complete object. 303 * 304 * @code 305 * shared_ptr<pair<int,int>> pii(new pair<int,int>()); 306 * shared_ptr<int> pi(pii, &pii->first); 307 * assert(pii.use_count() == 2); 308 * @endcode 309 */ 310 template<typename _Yp> 311 shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept 312 : __shared_ptr<_Tp>(__r, __p) { } 313 314 #if __cplusplus > 201703L 315 // _GLIBCXX_RESOLVE_LIB_DEFECTS 316 // 2996. Missing rvalue overloads for shared_ptr operations 317 /** 318 * @brief Constructs a `shared_ptr` instance that stores `__p` 319 * and shares ownership with `__r`. 320 * @param __r A `shared_ptr`. 321 * @param __p A pointer that will remain valid while `*__r` is valid. 322 * @post `get() == __p && !__r.use_count() && !__r.get()` 323 * @since C++17 324 * 325 * This can be used to construct a `shared_ptr` to a sub-object 326 * of an object managed by an existing `shared_ptr`. The complete 327 * object will remain valid while any `shared_ptr` owns it, even 328 * if they don't store a pointer to the complete object. 329 * 330 * @code 331 * shared_ptr<pair<int,int>> pii(new pair<int,int>()); 332 * shared_ptr<int> pi1(pii, &pii->first); 333 * assert(pii.use_count() == 2); 334 * shared_ptr<int> pi2(std::move(pii), &pii->second); 335 * assert(pii.use_count() == 0); 336 * @endcode 337 */ 338 template<typename _Yp> 339 shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept 340 : __shared_ptr<_Tp>(std::move(__r), __p) { } 341 #endif 342 /** 343 * @brief If @a __r is empty, constructs an empty %shared_ptr; 344 * otherwise construct a %shared_ptr that shares ownership 345 * with @a __r. 346 * @param __r A %shared_ptr. 347 * @post get() == __r.get() && use_count() == __r.use_count() 348 */ 349 template<typename _Yp, 350 typename = _Constructible<const shared_ptr<_Yp>&>> 351 shared_ptr(const shared_ptr<_Yp>& __r) noexcept 352 : __shared_ptr<_Tp>(__r) { } 353 354 /** 355 * @brief Move-constructs a %shared_ptr instance from @a __r. 356 * @param __r A %shared_ptr rvalue. 357 * @post *this contains the old value of @a __r, @a __r is empty. 358 */ 359 shared_ptr(shared_ptr&& __r) noexcept 360 : __shared_ptr<_Tp>(std::move(__r)) { } 361 362 /** 363 * @brief Move-constructs a %shared_ptr instance from @a __r. 364 * @param __r A %shared_ptr rvalue. 365 * @post *this contains the old value of @a __r, @a __r is empty. 366 */ 367 template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> 368 shared_ptr(shared_ptr<_Yp>&& __r) noexcept 369 : __shared_ptr<_Tp>(std::move(__r)) { } 370 371 /** 372 * @brief Constructs a %shared_ptr that shares ownership with @a __r 373 * and stores a copy of the pointer stored in @a __r. 374 * @param __r A weak_ptr. 375 * @post use_count() == __r.use_count() 376 * @throw bad_weak_ptr when __r.expired(), 377 * in which case the constructor has no effect. 378 */ 379 template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> 380 explicit shared_ptr(const weak_ptr<_Yp>& __r) 381 : __shared_ptr<_Tp>(__r) { } 382 383 #if _GLIBCXX_USE_DEPRECATED 384 #pragma GCC diagnostic push 385 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 386 template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> 387 shared_ptr(auto_ptr<_Yp>&& __r); 388 #pragma GCC diagnostic pop 389 #endif 390 391 // _GLIBCXX_RESOLVE_LIB_DEFECTS 392 // 2399. shared_ptr's constructor from unique_ptr should be constrained 393 template<typename _Yp, typename _Del, 394 typename = _Constructible<unique_ptr<_Yp, _Del>>> 395 shared_ptr(unique_ptr<_Yp, _Del>&& __r) 396 : __shared_ptr<_Tp>(std::move(__r)) { } 397 398 #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED 399 // This non-standard constructor exists to support conversions that 400 // were possible in C++11 and C++14 but are ill-formed in C++17. 401 // If an exception is thrown this constructor has no effect. 402 template<typename _Yp, typename _Del, 403 _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> 404 shared_ptr(unique_ptr<_Yp, _Del>&& __r) 405 : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } 406 #endif 407 408 /** 409 * @brief Construct an empty %shared_ptr. 410 * @post use_count() == 0 && get() == nullptr 411 */ 412 constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } 413 414 shared_ptr& operator=(const shared_ptr&) noexcept = default; 415 416 template<typename _Yp> 417 _Assignable<const shared_ptr<_Yp>&> 418 operator=(const shared_ptr<_Yp>& __r) noexcept 419 { 420 this->__shared_ptr<_Tp>::operator=(__r); 421 return *this; 422 } 423 424 #if _GLIBCXX_USE_DEPRECATED 425 #pragma GCC diagnostic push 426 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 427 template<typename _Yp> 428 _Assignable<auto_ptr<_Yp>> 429 operator=(auto_ptr<_Yp>&& __r) 430 { 431 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 432 return *this; 433 } 434 #pragma GCC diagnostic pop 435 #endif 436 437 shared_ptr& 438 operator=(shared_ptr&& __r) noexcept 439 { 440 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 441 return *this; 442 } 443 444 template<class _Yp> 445 _Assignable<shared_ptr<_Yp>> 446 operator=(shared_ptr<_Yp>&& __r) noexcept 447 { 448 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 449 return *this; 450 } 451 452 template<typename _Yp, typename _Del> 453 _Assignable<unique_ptr<_Yp, _Del>> 454 operator=(unique_ptr<_Yp, _Del>&& __r) 455 { 456 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 457 return *this; 458 } 459 460 private: 461 // This constructor is non-standard, it is used by allocate_shared. 462 template<typename _Alloc, typename... _Args> 463 shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args) 464 : __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...) 465 { } 466 467 template<typename _Yp, typename _Alloc, typename... _Args> 468 friend shared_ptr<_NonArray<_Yp>> 469 allocate_shared(const _Alloc&, _Args&&...); 470 471 template<typename _Yp, typename... _Args> 472 friend shared_ptr<_NonArray<_Yp>> 473 make_shared(_Args&&...); 474 475 #if __cpp_lib_shared_ptr_arrays >= 201707L 476 // This constructor is non-standard, it is used by allocate_shared<T[]>. 477 template<typename _Alloc, typename _Init = const remove_extent_t<_Tp>*> 478 shared_ptr(const _Sp_counted_array_base<_Alloc>& __a, 479 _Init __init = nullptr) 480 : __shared_ptr<_Tp>(__a, __init) 481 { } 482 483 template<typename _Yp, typename _Alloc> 484 friend shared_ptr<_UnboundedArray<_Yp>> 485 allocate_shared(const _Alloc&, size_t); 486 487 template<typename _Yp> 488 friend shared_ptr<_UnboundedArray<_Yp>> 489 make_shared(size_t); 490 491 template<typename _Yp, typename _Alloc> 492 friend shared_ptr<_UnboundedArray<_Yp>> 493 allocate_shared(const _Alloc&, size_t, const remove_extent_t<_Yp>&); 494 495 template<typename _Yp> 496 friend shared_ptr<_UnboundedArray<_Yp>> 497 make_shared(size_t, const remove_extent_t<_Yp>&); 498 499 template<typename _Yp, typename _Alloc> 500 friend shared_ptr<_BoundedArray<_Yp>> 501 allocate_shared(const _Alloc&); 502 503 template<typename _Yp> 504 friend shared_ptr<_BoundedArray<_Yp>> 505 make_shared(); 506 507 template<typename _Yp, typename _Alloc> 508 friend shared_ptr<_BoundedArray<_Yp>> 509 allocate_shared(const _Alloc&, const remove_extent_t<_Yp>&); 510 511 template<typename _Yp> 512 friend shared_ptr<_BoundedArray<_Yp>> 513 make_shared(const remove_extent_t<_Yp>&); 514 515 #if __cpp_lib_smart_ptr_for_overwrite 516 template<typename _Yp, typename _Alloc> 517 friend shared_ptr<_NotUnboundedArray<_Yp>> 518 allocate_shared_for_overwrite(const _Alloc&); 519 520 template<typename _Yp> 521 friend shared_ptr<_NotUnboundedArray<_Yp>> 522 make_shared_for_overwrite(); 523 524 template<typename _Yp, typename _Alloc> 525 friend shared_ptr<_UnboundedArray<_Yp>> 526 allocate_shared_for_overwrite(const _Alloc&, size_t); 527 528 template<typename _Yp> 529 friend shared_ptr<_UnboundedArray<_Yp>> 530 make_shared_for_overwrite(size_t); 531 #endif 532 #endif 533 534 // This constructor is non-standard, it is used by weak_ptr::lock(). 535 shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept 536 : __shared_ptr<_Tp>(__r, std::nothrow) { } 537 538 friend class weak_ptr<_Tp>; 539 }; 540 541 #if __cpp_deduction_guides >= 201606 542 template<typename _Tp> 543 shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; 544 template<typename _Tp, typename _Del> 545 shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; 546 #endif 547 548 // 20.7.2.2.7 shared_ptr comparisons 549 550 /// @relates shared_ptr @{ 551 552 /// Equality operator for shared_ptr objects, compares the stored pointers 553 template<typename _Tp, typename _Up> 554 _GLIBCXX_NODISCARD inline bool 555 operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 556 { return __a.get() == __b.get(); } 557 558 /// shared_ptr comparison with nullptr 559 template<typename _Tp> 560 _GLIBCXX_NODISCARD inline bool 561 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 562 { return !__a; } 563 564 #ifdef __cpp_lib_three_way_comparison 565 template<typename _Tp, typename _Up> 566 inline strong_ordering 567 operator<=>(const shared_ptr<_Tp>& __a, 568 const shared_ptr<_Up>& __b) noexcept 569 { return compare_three_way()(__a.get(), __b.get()); } 570 571 template<typename _Tp> 572 inline strong_ordering 573 operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 574 { 575 using pointer = typename shared_ptr<_Tp>::element_type*; 576 return compare_three_way()(__a.get(), static_cast<pointer>(nullptr)); 577 } 578 #else 579 /// shared_ptr comparison with nullptr 580 template<typename _Tp> 581 _GLIBCXX_NODISCARD inline bool 582 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 583 { return !__a; } 584 585 /// Inequality operator for shared_ptr objects, compares the stored pointers 586 template<typename _Tp, typename _Up> 587 _GLIBCXX_NODISCARD inline bool 588 operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 589 { return __a.get() != __b.get(); } 590 591 /// shared_ptr comparison with nullptr 592 template<typename _Tp> 593 _GLIBCXX_NODISCARD inline bool 594 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 595 { return (bool)__a; } 596 597 /// shared_ptr comparison with nullptr 598 template<typename _Tp> 599 _GLIBCXX_NODISCARD inline bool 600 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 601 { return (bool)__a; } 602 603 /// Relational operator for shared_ptr objects, compares the stored pointers 604 template<typename _Tp, typename _Up> 605 _GLIBCXX_NODISCARD inline bool 606 operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 607 { 608 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 609 using _Up_elt = typename shared_ptr<_Up>::element_type; 610 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; 611 return less<_Vp>()(__a.get(), __b.get()); 612 } 613 614 /// shared_ptr comparison with nullptr 615 template<typename _Tp> 616 _GLIBCXX_NODISCARD inline bool 617 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 618 { 619 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 620 return less<_Tp_elt*>()(__a.get(), nullptr); 621 } 622 623 /// shared_ptr comparison with nullptr 624 template<typename _Tp> 625 _GLIBCXX_NODISCARD inline bool 626 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 627 { 628 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 629 return less<_Tp_elt*>()(nullptr, __a.get()); 630 } 631 632 /// Relational operator for shared_ptr objects, compares the stored pointers 633 template<typename _Tp, typename _Up> 634 _GLIBCXX_NODISCARD inline bool 635 operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 636 { return !(__b < __a); } 637 638 /// shared_ptr comparison with nullptr 639 template<typename _Tp> 640 _GLIBCXX_NODISCARD inline bool 641 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 642 { return !(nullptr < __a); } 643 644 /// shared_ptr comparison with nullptr 645 template<typename _Tp> 646 _GLIBCXX_NODISCARD inline bool 647 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 648 { return !(__a < nullptr); } 649 650 /// Relational operator for shared_ptr objects, compares the stored pointers 651 template<typename _Tp, typename _Up> 652 _GLIBCXX_NODISCARD inline bool 653 operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 654 { return (__b < __a); } 655 656 /// shared_ptr comparison with nullptr 657 template<typename _Tp> 658 _GLIBCXX_NODISCARD inline bool 659 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 660 { return nullptr < __a; } 661 662 /// shared_ptr comparison with nullptr 663 template<typename _Tp> 664 _GLIBCXX_NODISCARD inline bool 665 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 666 { return __a < nullptr; } 667 668 /// Relational operator for shared_ptr objects, compares the stored pointers 669 template<typename _Tp, typename _Up> 670 _GLIBCXX_NODISCARD inline bool 671 operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 672 { return !(__a < __b); } 673 674 /// shared_ptr comparison with nullptr 675 template<typename _Tp> 676 _GLIBCXX_NODISCARD inline bool 677 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 678 { return !(__a < nullptr); } 679 680 /// shared_ptr comparison with nullptr 681 template<typename _Tp> 682 _GLIBCXX_NODISCARD inline bool 683 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 684 { return !(nullptr < __a); } 685 #endif 686 687 // 20.7.2.2.8 shared_ptr specialized algorithms. 688 689 /// Swap overload for shared_ptr 690 template<typename _Tp> 691 inline void 692 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept 693 { __a.swap(__b); } 694 695 // 20.7.2.2.9 shared_ptr casts. 696 697 /// Convert type of `shared_ptr`, via `static_cast` 698 template<typename _Tp, typename _Up> 699 inline shared_ptr<_Tp> 700 static_pointer_cast(const shared_ptr<_Up>& __r) noexcept 701 { 702 using _Sp = shared_ptr<_Tp>; 703 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); 704 } 705 706 /// Convert type of `shared_ptr`, via `const_cast` 707 template<typename _Tp, typename _Up> 708 inline shared_ptr<_Tp> 709 const_pointer_cast(const shared_ptr<_Up>& __r) noexcept 710 { 711 using _Sp = shared_ptr<_Tp>; 712 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); 713 } 714 715 /// Convert type of `shared_ptr`, via `dynamic_cast` 716 template<typename _Tp, typename _Up> 717 inline shared_ptr<_Tp> 718 dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept 719 { 720 using _Sp = shared_ptr<_Tp>; 721 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) 722 return _Sp(__r, __p); 723 return _Sp(); 724 } 725 726 #if __cplusplus >= 201703L 727 /// Convert type of `shared_ptr`, via `reinterpret_cast` 728 /// @since C++17 729 template<typename _Tp, typename _Up> 730 inline shared_ptr<_Tp> 731 reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept 732 { 733 using _Sp = shared_ptr<_Tp>; 734 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); 735 } 736 737 #if __cplusplus > 201703L 738 // _GLIBCXX_RESOLVE_LIB_DEFECTS 739 // 2996. Missing rvalue overloads for shared_ptr operations 740 741 /// Convert type of `shared_ptr` rvalue, via `static_cast` 742 /// @since C++20 743 template<typename _Tp, typename _Up> 744 inline shared_ptr<_Tp> 745 static_pointer_cast(shared_ptr<_Up>&& __r) noexcept 746 { 747 using _Sp = shared_ptr<_Tp>; 748 return _Sp(std::move(__r), 749 static_cast<typename _Sp::element_type*>(__r.get())); 750 } 751 752 /// Convert type of `shared_ptr` rvalue, via `const_cast` 753 /// @since C++20 754 template<typename _Tp, typename _Up> 755 inline shared_ptr<_Tp> 756 const_pointer_cast(shared_ptr<_Up>&& __r) noexcept 757 { 758 using _Sp = shared_ptr<_Tp>; 759 return _Sp(std::move(__r), 760 const_cast<typename _Sp::element_type*>(__r.get())); 761 } 762 763 /// Convert type of `shared_ptr` rvalue, via `dynamic_cast` 764 /// @since C++20 765 template<typename _Tp, typename _Up> 766 inline shared_ptr<_Tp> 767 dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept 768 { 769 using _Sp = shared_ptr<_Tp>; 770 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) 771 return _Sp(std::move(__r), __p); 772 return _Sp(); 773 } 774 775 /// Convert type of `shared_ptr` rvalue, via `reinterpret_cast` 776 /// @since C++20 777 template<typename _Tp, typename _Up> 778 inline shared_ptr<_Tp> 779 reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept 780 { 781 using _Sp = shared_ptr<_Tp>; 782 return _Sp(std::move(__r), 783 reinterpret_cast<typename _Sp::element_type*>(__r.get())); 784 } 785 #endif // C++20 786 #endif // C++17 787 788 /// @} 789 790 /** 791 * @brief A non-owning observer for a pointer owned by a shared_ptr 792 * @headerfile memory 793 * @since C++11 794 * 795 * A weak_ptr provides a safe alternative to a raw pointer when you want 796 * a non-owning reference to an object that is managed by a shared_ptr. 797 * 798 * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr 799 * that shares ownership with every other shared_ptr that already owns 800 * the pointer. In other words you can upgrade from a non-owning "weak" 801 * reference to an owning shared_ptr, without having access to any of 802 * the existing shared_ptr objects. 803 * 804 * Also unlike a raw pointer, a weak_ptr does not become "dangling" after 805 * the object it points to has been destroyed. Instead, a weak_ptr 806 * becomes _expired_ and can no longer be converted to a shared_ptr that 807 * owns the freed pointer, so you cannot accidentally access the pointed-to 808 * object after it has been destroyed. 809 */ 810 template<typename _Tp> 811 class weak_ptr : public __weak_ptr<_Tp> 812 { 813 template<typename _Arg> 814 using _Constructible = typename enable_if< 815 is_constructible<__weak_ptr<_Tp>, _Arg>::value 816 >::type; 817 818 template<typename _Arg> 819 using _Assignable = typename enable_if< 820 is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& 821 >::type; 822 823 public: 824 constexpr weak_ptr() noexcept = default; 825 826 template<typename _Yp, 827 typename = _Constructible<const shared_ptr<_Yp>&>> 828 weak_ptr(const shared_ptr<_Yp>& __r) noexcept 829 : __weak_ptr<_Tp>(__r) { } 830 831 weak_ptr(const weak_ptr&) noexcept = default; 832 833 template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> 834 weak_ptr(const weak_ptr<_Yp>& __r) noexcept 835 : __weak_ptr<_Tp>(__r) { } 836 837 weak_ptr(weak_ptr&&) noexcept = default; 838 839 template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> 840 weak_ptr(weak_ptr<_Yp>&& __r) noexcept 841 : __weak_ptr<_Tp>(std::move(__r)) { } 842 843 weak_ptr& 844 operator=(const weak_ptr& __r) noexcept = default; 845 846 template<typename _Yp> 847 _Assignable<const weak_ptr<_Yp>&> 848 operator=(const weak_ptr<_Yp>& __r) noexcept 849 { 850 this->__weak_ptr<_Tp>::operator=(__r); 851 return *this; 852 } 853 854 template<typename _Yp> 855 _Assignable<const shared_ptr<_Yp>&> 856 operator=(const shared_ptr<_Yp>& __r) noexcept 857 { 858 this->__weak_ptr<_Tp>::operator=(__r); 859 return *this; 860 } 861 862 weak_ptr& 863 operator=(weak_ptr&& __r) noexcept = default; 864 865 template<typename _Yp> 866 _Assignable<weak_ptr<_Yp>> 867 operator=(weak_ptr<_Yp>&& __r) noexcept 868 { 869 this->__weak_ptr<_Tp>::operator=(std::move(__r)); 870 return *this; 871 } 872 873 shared_ptr<_Tp> 874 lock() const noexcept 875 { return shared_ptr<_Tp>(*this, std::nothrow); } 876 }; 877 878 #if __cpp_deduction_guides >= 201606 879 template<typename _Tp> 880 weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; 881 #endif 882 883 // 20.7.2.3.6 weak_ptr specialized algorithms. 884 /// Swap overload for weak_ptr 885 /// @relates weak_ptr 886 template<typename _Tp> 887 inline void 888 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept 889 { __a.swap(__b); } 890 891 892 /// Primary template owner_less 893 template<typename _Tp = void> 894 struct owner_less; 895 896 /// Void specialization of owner_less compares either shared_ptr or weak_ptr 897 template<> 898 struct owner_less<void> : _Sp_owner_less<void, void> 899 { }; 900 901 /// Partial specialization of owner_less for shared_ptr. 902 template<typename _Tp> 903 struct owner_less<shared_ptr<_Tp>> 904 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> 905 { }; 906 907 /// Partial specialization of owner_less for weak_ptr. 908 template<typename _Tp> 909 struct owner_less<weak_ptr<_Tp>> 910 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> 911 { }; 912 913 /** 914 * @brief Base class allowing use of the member function `shared_from_this`. 915 * @headerfile memory 916 * @since C++11 917 */ 918 template<typename _Tp> 919 class enable_shared_from_this 920 { 921 protected: 922 constexpr enable_shared_from_this() noexcept { } 923 924 enable_shared_from_this(const enable_shared_from_this&) noexcept { } 925 926 enable_shared_from_this& 927 operator=(const enable_shared_from_this&) noexcept 928 { return *this; } 929 930 ~enable_shared_from_this() { } 931 932 public: 933 shared_ptr<_Tp> 934 shared_from_this() 935 { return shared_ptr<_Tp>(this->_M_weak_this); } 936 937 shared_ptr<const _Tp> 938 shared_from_this() const 939 { return shared_ptr<const _Tp>(this->_M_weak_this); } 940 941 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 942 #define __cpp_lib_enable_shared_from_this 201603L 943 /** @{ 944 * Get a `weak_ptr` referring to the object that has `*this` as its base. 945 * @since C++17 946 */ 947 weak_ptr<_Tp> 948 weak_from_this() noexcept 949 { return this->_M_weak_this; } 950 951 weak_ptr<const _Tp> 952 weak_from_this() const noexcept 953 { return this->_M_weak_this; } 954 /// @} 955 #endif 956 957 private: 958 template<typename _Tp1> 959 void 960 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept 961 { _M_weak_this._M_assign(__p, __n); } 962 963 // Found by ADL when this is an associated class. 964 friend const enable_shared_from_this* 965 __enable_shared_from_this_base(const __shared_count<>&, 966 const enable_shared_from_this* __p) 967 { return __p; } 968 969 template<typename, _Lock_policy> 970 friend class __shared_ptr; 971 972 mutable weak_ptr<_Tp> _M_weak_this; 973 }; 974 975 /// @relates shared_ptr @{ 976 977 /** 978 * @brief Create an object that is owned by a shared_ptr. 979 * @param __a An allocator. 980 * @param __args Arguments for the @a _Tp object's constructor. 981 * @return A shared_ptr that owns the newly created object. 982 * @throw An exception thrown from @a _Alloc::allocate or from the 983 * constructor of @a _Tp. 984 * 985 * A copy of @a __a will be used to allocate memory for the shared_ptr 986 * and the new object. 987 */ 988 template<typename _Tp, typename _Alloc, typename... _Args> 989 inline shared_ptr<_NonArray<_Tp>> 990 allocate_shared(const _Alloc& __a, _Args&&... __args) 991 { 992 return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a}, 993 std::forward<_Args>(__args)...); 994 } 995 996 /** 997 * @brief Create an object that is owned by a shared_ptr. 998 * @param __args Arguments for the @a _Tp object's constructor. 999 * @return A shared_ptr that owns the newly created object. 1000 * @throw std::bad_alloc, or an exception thrown from the 1001 * constructor of @a _Tp. 1002 */ 1003 template<typename _Tp, typename... _Args> 1004 inline shared_ptr<_NonArray<_Tp>> 1005 make_shared(_Args&&... __args) 1006 { 1007 using _Alloc = allocator<void>; 1008 _Alloc __a; 1009 return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a}, 1010 std::forward<_Args>(__args)...); 1011 } 1012 1013 #if __cpp_lib_shared_ptr_arrays >= 201707L 1014 /// @cond undocumented 1015 template<typename _Tp, typename _Alloc = allocator<void>> 1016 auto 1017 __make_shared_arr_tag(size_t __n, const _Alloc& __a = _Alloc()) noexcept 1018 { 1019 using _Up = remove_all_extents_t<_Tp>; 1020 using _UpAlloc = __alloc_rebind<_Alloc, _Up>; 1021 size_t __s = sizeof(remove_extent_t<_Tp>) / sizeof(_Up); 1022 if (__builtin_mul_overflow(__s, __n, &__n)) 1023 std::__throw_bad_array_new_length(); 1024 return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n}; 1025 } 1026 /// @endcond 1027 1028 template<typename _Tp, typename _Alloc> 1029 inline shared_ptr<_UnboundedArray<_Tp>> 1030 allocate_shared(const _Alloc& __a, size_t __n) 1031 { 1032 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a)); 1033 } 1034 1035 template<typename _Tp> 1036 inline shared_ptr<_UnboundedArray<_Tp>> 1037 make_shared(size_t __n) 1038 { 1039 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n)); 1040 } 1041 1042 template<typename _Tp, typename _Alloc> 1043 inline shared_ptr<_UnboundedArray<_Tp>> 1044 allocate_shared(const _Alloc& __a, size_t __n, 1045 const remove_extent_t<_Tp>& __u) 1046 { 1047 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a), 1048 std::__addressof(__u)); 1049 } 1050 1051 template<typename _Tp> 1052 inline shared_ptr<_UnboundedArray<_Tp>> 1053 make_shared(size_t __n, const remove_extent_t<_Tp>& __u) 1054 { 1055 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n), 1056 std::__addressof(__u)); 1057 } 1058 1059 /// @cond undocumented 1060 template<typename _Tp, typename _Alloc = allocator<void>> 1061 auto 1062 __make_shared_arrN_tag(const _Alloc& __a = _Alloc()) noexcept 1063 { 1064 using _Up = remove_all_extents_t<_Tp>; 1065 using _UpAlloc = __alloc_rebind<_Alloc, _Up>; 1066 size_t __n = sizeof(_Tp) / sizeof(_Up); 1067 return _Sp_counted_array_base<_UpAlloc>{_UpAlloc(__a), __n}; 1068 } 1069 /// @endcond 1070 1071 template<typename _Tp, typename _Alloc> 1072 inline shared_ptr<_BoundedArray<_Tp>> 1073 allocate_shared(const _Alloc& __a) 1074 { 1075 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a)); 1076 } 1077 1078 template<typename _Tp> 1079 inline shared_ptr<_BoundedArray<_Tp>> 1080 make_shared() 1081 { 1082 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>()); 1083 } 1084 1085 template<typename _Tp, typename _Alloc> 1086 inline shared_ptr<_BoundedArray<_Tp>> 1087 allocate_shared(const _Alloc& __a, const remove_extent_t<_Tp>& __u) 1088 { 1089 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a), 1090 std::__addressof(__u)); 1091 } 1092 1093 template<typename _Tp> 1094 inline shared_ptr<_BoundedArray<_Tp>> 1095 make_shared(const remove_extent_t<_Tp>& __u) 1096 { 1097 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(), 1098 std::__addressof(__u)); 1099 } 1100 1101 #if __cpp_lib_smart_ptr_for_overwrite 1102 template<typename _Tp, typename _Alloc> 1103 inline shared_ptr<_NotUnboundedArray<_Tp>> 1104 allocate_shared_for_overwrite(const _Alloc& __a) 1105 { 1106 if constexpr (is_array_v<_Tp>) 1107 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(__a), 1108 _Sp_overwrite_tag{}); 1109 else 1110 { 1111 // Rebind the allocator to _Sp_overwrite_tag, so that the 1112 // relevant _Sp_counted_ptr_inplace specialization is used. 1113 using _Alloc2 = __alloc_rebind<_Alloc, _Sp_overwrite_tag>; 1114 _Alloc2 __a2 = __a; 1115 return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc2>{__a2}); 1116 } 1117 } 1118 1119 template<typename _Tp> 1120 inline shared_ptr<_NotUnboundedArray<_Tp>> 1121 make_shared_for_overwrite() 1122 { 1123 if constexpr (is_array_v<_Tp>) 1124 return shared_ptr<_Tp>(std::__make_shared_arrN_tag<_Tp>(), 1125 _Sp_overwrite_tag{}); 1126 else 1127 { 1128 using _Alloc = allocator<_Sp_overwrite_tag>; 1129 return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{{}}); 1130 } 1131 } 1132 1133 template<typename _Tp, typename _Alloc> 1134 inline shared_ptr<_UnboundedArray<_Tp>> 1135 allocate_shared_for_overwrite(const _Alloc& __a, size_t __n) 1136 { 1137 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n, __a), 1138 _Sp_overwrite_tag{}); 1139 } 1140 1141 template<typename _Tp> 1142 inline shared_ptr<_UnboundedArray<_Tp>> 1143 make_shared_for_overwrite(size_t __n) 1144 { 1145 return shared_ptr<_Tp>(std::__make_shared_arr_tag<_Tp>(__n), 1146 _Sp_overwrite_tag{}); 1147 } 1148 #endif // smart_ptr_for_overwrite 1149 #endif // shared_ptr_arrays 1150 1151 /// std::hash specialization for shared_ptr. 1152 template<typename _Tp> 1153 struct hash<shared_ptr<_Tp>> 1154 : public __hash_base<size_t, shared_ptr<_Tp>> 1155 { 1156 size_t 1157 operator()(const shared_ptr<_Tp>& __s) const noexcept 1158 { 1159 return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); 1160 } 1161 }; 1162 1163 /// @} relates shared_ptr 1164 /// @} group pointer_abstractions 1165 1166 #if __cplusplus >= 201703L 1167 namespace __detail::__variant 1168 { 1169 template<typename> struct _Never_valueless_alt; // see <variant> 1170 1171 // Provide the strong exception-safety guarantee when emplacing a 1172 // shared_ptr into a variant. 1173 template<typename _Tp> 1174 struct _Never_valueless_alt<std::shared_ptr<_Tp>> 1175 : std::true_type 1176 { }; 1177 1178 // Provide the strong exception-safety guarantee when emplacing a 1179 // weak_ptr into a variant. 1180 template<typename _Tp> 1181 struct _Never_valueless_alt<std::weak_ptr<_Tp>> 1182 : std::true_type 1183 { }; 1184 } // namespace __detail::__variant 1185 #endif // C++17 1186 1187 _GLIBCXX_END_NAMESPACE_VERSION 1188 } // namespace 1189 1190 #endif // _SHARED_PTR_H
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