1 // shared_ptr and weak_ptr implementation details -*- C++ -*- 2 3 // Copyright (C) 2007-2018 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 // 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 bits/shared_ptr_base.h 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_BASE_H 50 #define _SHARED_PTR_BASE_H 1 51 52 #if __cpp_rtti 53 # include <typeinfo> 54 #endif 55 #include <bits/allocated_ptr.h> 56 #include <bits/refwrap.h> 57 #include <bits/stl_function.h> 58 #include <ext/aligned_buffer.h> 59 60 namespace std _GLIBCXX_VISIBILITY(default) 61 { 62 #if !__cpp_rtti 63 class type_info; 64 #endif 65 66 _GLIBCXX_BEGIN_NAMESPACE_VERSION 67 68 #if _GLIBCXX_USE_DEPRECATED 69 #pragma GCC diagnostic push 70 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 71 template<typename> class auto_ptr; 72 #pragma GCC diagnostic pop 73 #endif 74 75 /** 76 * @brief Exception possibly thrown by @c shared_ptr. 77 * @ingroup exceptions 78 */ 79 class bad_weak_ptr : public std::exception 80 { 81 public: 82 virtual char const* what() const noexcept; 83 84 virtual ~bad_weak_ptr() noexcept; 85 }; 86 87 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 88 inline void 89 __throw_bad_weak_ptr() 90 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } 91 92 using __gnu_cxx::_Lock_policy; 93 using __gnu_cxx::__default_lock_policy; 94 using __gnu_cxx::_S_single; 95 using __gnu_cxx::_S_mutex; 96 using __gnu_cxx::_S_atomic; 97 98 // Empty helper class except when the template argument is _S_mutex. 99 template<_Lock_policy _Lp> 100 class _Mutex_base 101 { 102 protected: 103 // The atomic policy uses fully-fenced builtins, single doesn't care. 104 enum { _S_need_barriers = 0 }; 105 }; 106 107 template<> 108 class _Mutex_base<_S_mutex> 109 : public __gnu_cxx::__mutex 110 { 111 protected: 112 // This policy is used when atomic builtins are not available. 113 // The replacement atomic operations might not have the necessary 114 // memory barriers. 115 enum { _S_need_barriers = 1 }; 116 }; 117 118 template<_Lock_policy _Lp = __default_lock_policy> 119 class _Sp_counted_base 120 : public _Mutex_base<_Lp> 121 { 122 public: 123 _Sp_counted_base() noexcept 124 : _M_use_count(1), _M_weak_count(1) { } 125 126 virtual 127 ~_Sp_counted_base() noexcept 128 { } 129 130 // Called when _M_use_count drops to zero, to release the resources 131 // managed by *this. 132 virtual void 133 _M_dispose() noexcept = 0; 134 135 // Called when _M_weak_count drops to zero. 136 virtual void 137 _M_destroy() noexcept 138 { delete this; } 139 140 virtual void* 141 _M_get_deleter(const std::type_info&) noexcept = 0; 142 143 void 144 _M_add_ref_copy() 145 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 146 147 void 148 _M_add_ref_lock(); 149 150 bool 151 _M_add_ref_lock_nothrow(); 152 153 void 154 _M_release() noexcept 155 { 156 // Be race-detector-friendly. For more info see bits/c++config. 157 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 158 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 159 { 160 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 161 _M_dispose(); 162 // There must be a memory barrier between dispose() and destroy() 163 // to ensure that the effects of dispose() are observed in the 164 // thread that runs destroy(). 165 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 166 if (_Mutex_base<_Lp>::_S_need_barriers) 167 { 168 __atomic_thread_fence (__ATOMIC_ACQ_REL); 169 } 170 171 // Be race-detector-friendly. For more info see bits/c++config. 172 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 173 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 174 -1) == 1) 175 { 176 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 177 _M_destroy(); 178 } 179 } 180 } 181 182 void 183 _M_weak_add_ref() noexcept 184 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 185 186 void 187 _M_weak_release() noexcept 188 { 189 // Be race-detector-friendly. For more info see bits/c++config. 190 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 191 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 192 { 193 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 194 if (_Mutex_base<_Lp>::_S_need_barriers) 195 { 196 // See _M_release(), 197 // destroy() must observe results of dispose() 198 __atomic_thread_fence (__ATOMIC_ACQ_REL); 199 } 200 _M_destroy(); 201 } 202 } 203 204 long 205 _M_get_use_count() const noexcept 206 { 207 // No memory barrier is used here so there is no synchronization 208 // with other threads. 209 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); 210 } 211 212 private: 213 _Sp_counted_base(_Sp_counted_base const&) = delete; 214 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; 215 216 _Atomic_word _M_use_count; // #shared 217 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 218 }; 219 220 template<> 221 inline void 222 _Sp_counted_base<_S_single>:: 223 _M_add_ref_lock() 224 { 225 if (_M_use_count == 0) 226 __throw_bad_weak_ptr(); 227 ++_M_use_count; 228 } 229 230 template<> 231 inline void 232 _Sp_counted_base<_S_mutex>:: 233 _M_add_ref_lock() 234 { 235 __gnu_cxx::__scoped_lock sentry(*this); 236 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 237 { 238 _M_use_count = 0; 239 __throw_bad_weak_ptr(); 240 } 241 } 242 243 template<> 244 inline void 245 _Sp_counted_base<_S_atomic>:: 246 _M_add_ref_lock() 247 { 248 // Perform lock-free add-if-not-zero operation. 249 _Atomic_word __count = _M_get_use_count(); 250 do 251 { 252 if (__count == 0) 253 __throw_bad_weak_ptr(); 254 // Replace the current counter value with the old value + 1, as 255 // long as it's not changed meanwhile. 256 } 257 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 258 true, __ATOMIC_ACQ_REL, 259 __ATOMIC_RELAXED)); 260 } 261 262 template<> 263 inline bool 264 _Sp_counted_base<_S_single>:: 265 _M_add_ref_lock_nothrow() 266 { 267 if (_M_use_count == 0) 268 return false; 269 ++_M_use_count; 270 return true; 271 } 272 273 template<> 274 inline bool 275 _Sp_counted_base<_S_mutex>:: 276 _M_add_ref_lock_nothrow() 277 { 278 __gnu_cxx::__scoped_lock sentry(*this); 279 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 280 { 281 _M_use_count = 0; 282 return false; 283 } 284 return true; 285 } 286 287 template<> 288 inline bool 289 _Sp_counted_base<_S_atomic>:: 290 _M_add_ref_lock_nothrow() 291 { 292 // Perform lock-free add-if-not-zero operation. 293 _Atomic_word __count = _M_get_use_count(); 294 do 295 { 296 if (__count == 0) 297 return false; 298 // Replace the current counter value with the old value + 1, as 299 // long as it's not changed meanwhile. 300 } 301 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 302 true, __ATOMIC_ACQ_REL, 303 __ATOMIC_RELAXED)); 304 return true; 305 } 306 307 template<> 308 inline void 309 _Sp_counted_base<_S_single>::_M_add_ref_copy() 310 { ++_M_use_count; } 311 312 template<> 313 inline void 314 _Sp_counted_base<_S_single>::_M_release() noexcept 315 { 316 if (--_M_use_count == 0) 317 { 318 _M_dispose(); 319 if (--_M_weak_count == 0) 320 _M_destroy(); 321 } 322 } 323 324 template<> 325 inline void 326 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept 327 { ++_M_weak_count; } 328 329 template<> 330 inline void 331 _Sp_counted_base<_S_single>::_M_weak_release() noexcept 332 { 333 if (--_M_weak_count == 0) 334 _M_destroy(); 335 } 336 337 template<> 338 inline long 339 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept 340 { return _M_use_count; } 341 342 343 // Forward declarations. 344 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 345 class __shared_ptr; 346 347 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 348 class __weak_ptr; 349 350 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 351 class __enable_shared_from_this; 352 353 template<typename _Tp> 354 class shared_ptr; 355 356 template<typename _Tp> 357 class weak_ptr; 358 359 template<typename _Tp> 360 struct owner_less; 361 362 template<typename _Tp> 363 class enable_shared_from_this; 364 365 template<_Lock_policy _Lp = __default_lock_policy> 366 class __weak_count; 367 368 template<_Lock_policy _Lp = __default_lock_policy> 369 class __shared_count; 370 371 372 // Counted ptr with no deleter or allocator support 373 template<typename _Ptr, _Lock_policy _Lp> 374 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> 375 { 376 public: 377 explicit 378 _Sp_counted_ptr(_Ptr __p) noexcept 379 : _M_ptr(__p) { } 380 381 virtual void 382 _M_dispose() noexcept 383 { delete _M_ptr; } 384 385 virtual void 386 _M_destroy() noexcept 387 { delete this; } 388 389 virtual void* 390 _M_get_deleter(const std::type_info&) noexcept 391 { return nullptr; } 392 393 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 394 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 395 396 private: 397 _Ptr _M_ptr; 398 }; 399 400 template<> 401 inline void 402 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } 403 404 template<> 405 inline void 406 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } 407 408 template<> 409 inline void 410 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } 411 412 template<int _Nm, typename _Tp, 413 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)> 414 struct _Sp_ebo_helper; 415 416 /// Specialization using EBO. 417 template<int _Nm, typename _Tp> 418 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp 419 { 420 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { } 421 explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { } 422 423 static _Tp& 424 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); } 425 }; 426 427 /// Specialization not using EBO. 428 template<int _Nm, typename _Tp> 429 struct _Sp_ebo_helper<_Nm, _Tp, false> 430 { 431 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { } 432 explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { } 433 434 static _Tp& 435 _S_get(_Sp_ebo_helper& __eboh) 436 { return __eboh._M_tp; } 437 438 private: 439 _Tp _M_tp; 440 }; 441 442 // Support for custom deleter and/or allocator 443 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 444 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> 445 { 446 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc> 447 { 448 typedef _Sp_ebo_helper<0, _Deleter> _Del_base; 449 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base; 450 451 public: 452 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 453 : _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a) 454 { } 455 456 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); } 457 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); } 458 459 _Ptr _M_ptr; 460 }; 461 462 public: 463 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>; 464 465 // __d(__p) must not throw. 466 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept 467 : _M_impl(__p, std::move(__d), _Alloc()) { } 468 469 // __d(__p) must not throw. 470 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 471 : _M_impl(__p, std::move(__d), __a) { } 472 473 ~_Sp_counted_deleter() noexcept { } 474 475 virtual void 476 _M_dispose() noexcept 477 { _M_impl._M_del()(_M_impl._M_ptr); } 478 479 virtual void 480 _M_destroy() noexcept 481 { 482 __allocator_type __a(_M_impl._M_alloc()); 483 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 484 this->~_Sp_counted_deleter(); 485 } 486 487 virtual void* 488 _M_get_deleter(const std::type_info& __ti) noexcept 489 { 490 #if __cpp_rtti 491 // _GLIBCXX_RESOLVE_LIB_DEFECTS 492 // 2400. shared_ptr's get_deleter() should use addressof() 493 return __ti == typeid(_Deleter) 494 ? std::__addressof(_M_impl._M_del()) 495 : nullptr; 496 #else 497 return nullptr; 498 #endif 499 } 500 501 private: 502 _Impl _M_impl; 503 }; 504 505 // helpers for make_shared / allocate_shared 506 507 struct _Sp_make_shared_tag 508 { 509 #if !__cpp_rtti 510 private: 511 template<typename _Tp, _Lock_policy _Lp> 512 friend class __shared_ptr; 513 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 514 friend class _Sp_counted_ptr_inplace; 515 516 static const type_info& 517 _S_ti() noexcept 518 { 519 static constexpr _Sp_make_shared_tag __tag; 520 return reinterpret_cast<const type_info&>(__tag); 521 } 522 #endif 523 }; 524 525 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 526 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> 527 { 528 class _Impl : _Sp_ebo_helper<0, _Alloc> 529 { 530 typedef _Sp_ebo_helper<0, _Alloc> _A_base; 531 532 public: 533 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { } 534 535 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); } 536 537 __gnu_cxx::__aligned_buffer<_Tp> _M_storage; 538 }; 539 540 public: 541 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>; 542 543 template<typename... _Args> 544 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 545 : _M_impl(__a) 546 { 547 // _GLIBCXX_RESOLVE_LIB_DEFECTS 548 // 2070. allocate_shared should use allocator_traits<A>::construct 549 allocator_traits<_Alloc>::construct(__a, _M_ptr(), 550 std::forward<_Args>(__args)...); // might throw 551 } 552 553 ~_Sp_counted_ptr_inplace() noexcept { } 554 555 virtual void 556 _M_dispose() noexcept 557 { 558 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr()); 559 } 560 561 // Override because the allocator needs to know the dynamic type 562 virtual void 563 _M_destroy() noexcept 564 { 565 __allocator_type __a(_M_impl._M_alloc()); 566 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 567 this->~_Sp_counted_ptr_inplace(); 568 } 569 570 // Sneaky trick so __shared_ptr can get the managed pointer 571 virtual void* 572 _M_get_deleter(const std::type_info& __ti) noexcept 573 { 574 #if __cpp_rtti 575 if (__ti == typeid(_Sp_make_shared_tag)) 576 #else 577 if (&__ti == &_Sp_make_shared_tag::_S_ti()) 578 #endif 579 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr()); 580 return nullptr; 581 } 582 583 private: 584 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); } 585 586 _Impl _M_impl; 587 }; 588 589 // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>. 590 struct __sp_array_delete 591 { 592 template<typename _Yp> 593 void operator()(_Yp* __p) const { delete[] __p; } 594 }; 595 596 template<_Lock_policy _Lp> 597 class __shared_count 598 { 599 public: 600 constexpr __shared_count() noexcept : _M_pi(0) 601 { } 602 603 template<typename _Ptr> 604 explicit 605 __shared_count(_Ptr __p) : _M_pi(0) 606 { 607 __try 608 { 609 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 610 } 611 __catch(...) 612 { 613 delete __p; 614 __throw_exception_again; 615 } 616 } 617 618 template<typename _Ptr> 619 __shared_count(_Ptr __p, /* is_array = */ false_type) 620 : __shared_count(__p) 621 { } 622 623 template<typename _Ptr> 624 __shared_count(_Ptr __p, /* is_array = */ true_type) 625 : __shared_count(__p, __sp_array_delete{}, allocator<void>()) 626 { } 627 628 template<typename _Ptr, typename _Deleter> 629 __shared_count(_Ptr __p, _Deleter __d) 630 : __shared_count(__p, std::move(__d), allocator<void>()) 631 { } 632 633 template<typename _Ptr, typename _Deleter, typename _Alloc> 634 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 635 { 636 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 637 __try 638 { 639 typename _Sp_cd_type::__allocator_type __a2(__a); 640 auto __guard = std::__allocate_guarded(__a2); 641 _Sp_cd_type* __mem = __guard.get(); 642 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a)); 643 _M_pi = __mem; 644 __guard = nullptr; 645 } 646 __catch(...) 647 { 648 __d(__p); // Call _Deleter on __p. 649 __throw_exception_again; 650 } 651 } 652 653 template<typename _Tp, typename _Alloc, typename... _Args> 654 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 655 _Args&&... __args) 656 : _M_pi(0) 657 { 658 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 659 typename _Sp_cp_type::__allocator_type __a2(__a); 660 auto __guard = std::__allocate_guarded(__a2); 661 _Sp_cp_type* __mem = __guard.get(); 662 ::new (__mem) _Sp_cp_type(std::move(__a), 663 std::forward<_Args>(__args)...); 664 _M_pi = __mem; 665 __guard = nullptr; 666 } 667 668 #if _GLIBCXX_USE_DEPRECATED 669 #pragma GCC diagnostic push 670 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 671 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 672 template<typename _Tp> 673 explicit 674 __shared_count(std::auto_ptr<_Tp>&& __r); 675 #pragma GCC diagnostic pop 676 #endif 677 678 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 679 template<typename _Tp, typename _Del> 680 explicit 681 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0) 682 { 683 // _GLIBCXX_RESOLVE_LIB_DEFECTS 684 // 2415. Inconsistency between unique_ptr and shared_ptr 685 if (__r.get() == nullptr) 686 return; 687 688 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer; 689 using _Del2 = typename conditional<is_reference<_Del>::value, 690 reference_wrapper<typename remove_reference<_Del>::type>, 691 _Del>::type; 692 using _Sp_cd_type 693 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>; 694 using _Alloc = allocator<_Sp_cd_type>; 695 using _Alloc_traits = allocator_traits<_Alloc>; 696 _Alloc __a; 697 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1); 698 _Alloc_traits::construct(__a, __mem, __r.release(), 699 __r.get_deleter()); // non-throwing 700 _M_pi = __mem; 701 } 702 703 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 704 explicit __shared_count(const __weak_count<_Lp>& __r); 705 706 // Does not throw if __r._M_get_use_count() == 0, caller must check. 707 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t); 708 709 ~__shared_count() noexcept 710 { 711 if (_M_pi != nullptr) 712 _M_pi->_M_release(); 713 } 714 715 __shared_count(const __shared_count& __r) noexcept 716 : _M_pi(__r._M_pi) 717 { 718 if (_M_pi != 0) 719 _M_pi->_M_add_ref_copy(); 720 } 721 722 __shared_count& 723 operator=(const __shared_count& __r) noexcept 724 { 725 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 726 if (__tmp != _M_pi) 727 { 728 if (__tmp != 0) 729 __tmp->_M_add_ref_copy(); 730 if (_M_pi != 0) 731 _M_pi->_M_release(); 732 _M_pi = __tmp; 733 } 734 return *this; 735 } 736 737 void 738 _M_swap(__shared_count& __r) noexcept 739 { 740 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 741 __r._M_pi = _M_pi; 742 _M_pi = __tmp; 743 } 744 745 long 746 _M_get_use_count() const noexcept 747 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 748 749 bool 750 _M_unique() const noexcept 751 { return this->_M_get_use_count() == 1; } 752 753 void* 754 _M_get_deleter(const std::type_info& __ti) const noexcept 755 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; } 756 757 bool 758 _M_less(const __shared_count& __rhs) const noexcept 759 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 760 761 bool 762 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 763 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 764 765 // Friend function injected into enclosing namespace and found by ADL 766 friend inline bool 767 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 768 { return __a._M_pi == __b._M_pi; } 769 770 private: 771 friend class __weak_count<_Lp>; 772 773 _Sp_counted_base<_Lp>* _M_pi; 774 }; 775 776 777 template<_Lock_policy _Lp> 778 class __weak_count 779 { 780 public: 781 constexpr __weak_count() noexcept : _M_pi(nullptr) 782 { } 783 784 __weak_count(const __shared_count<_Lp>& __r) noexcept 785 : _M_pi(__r._M_pi) 786 { 787 if (_M_pi != nullptr) 788 _M_pi->_M_weak_add_ref(); 789 } 790 791 __weak_count(const __weak_count& __r) noexcept 792 : _M_pi(__r._M_pi) 793 { 794 if (_M_pi != nullptr) 795 _M_pi->_M_weak_add_ref(); 796 } 797 798 __weak_count(__weak_count&& __r) noexcept 799 : _M_pi(__r._M_pi) 800 { __r._M_pi = nullptr; } 801 802 ~__weak_count() noexcept 803 { 804 if (_M_pi != nullptr) 805 _M_pi->_M_weak_release(); 806 } 807 808 __weak_count& 809 operator=(const __shared_count<_Lp>& __r) noexcept 810 { 811 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 812 if (__tmp != nullptr) 813 __tmp->_M_weak_add_ref(); 814 if (_M_pi != nullptr) 815 _M_pi->_M_weak_release(); 816 _M_pi = __tmp; 817 return *this; 818 } 819 820 __weak_count& 821 operator=(const __weak_count& __r) noexcept 822 { 823 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 824 if (__tmp != nullptr) 825 __tmp->_M_weak_add_ref(); 826 if (_M_pi != nullptr) 827 _M_pi->_M_weak_release(); 828 _M_pi = __tmp; 829 return *this; 830 } 831 832 __weak_count& 833 operator=(__weak_count&& __r) noexcept 834 { 835 if (_M_pi != nullptr) 836 _M_pi->_M_weak_release(); 837 _M_pi = __r._M_pi; 838 __r._M_pi = nullptr; 839 return *this; 840 } 841 842 void 843 _M_swap(__weak_count& __r) noexcept 844 { 845 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 846 __r._M_pi = _M_pi; 847 _M_pi = __tmp; 848 } 849 850 long 851 _M_get_use_count() const noexcept 852 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; } 853 854 bool 855 _M_less(const __weak_count& __rhs) const noexcept 856 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 857 858 bool 859 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 860 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 861 862 // Friend function injected into enclosing namespace and found by ADL 863 friend inline bool 864 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 865 { return __a._M_pi == __b._M_pi; } 866 867 private: 868 friend class __shared_count<_Lp>; 869 870 _Sp_counted_base<_Lp>* _M_pi; 871 }; 872 873 // Now that __weak_count is defined we can define this constructor: 874 template<_Lock_policy _Lp> 875 inline 876 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r) 877 : _M_pi(__r._M_pi) 878 { 879 if (_M_pi != nullptr) 880 _M_pi->_M_add_ref_lock(); 881 else 882 __throw_bad_weak_ptr(); 883 } 884 885 // Now that __weak_count is defined we can define this constructor: 886 template<_Lock_policy _Lp> 887 inline 888 __shared_count<_Lp>:: 889 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t) 890 : _M_pi(__r._M_pi) 891 { 892 if (_M_pi != nullptr) 893 if (!_M_pi->_M_add_ref_lock_nothrow()) 894 _M_pi = nullptr; 895 } 896 897 #define __cpp_lib_shared_ptr_arrays 201603 898 899 // Helper traits for shared_ptr of array: 900 901 // A pointer type Y* is said to be compatible with a pointer type T* when 902 // either Y* is convertible to T* or Y is U[N] and T is U cv []. 903 template<typename _Yp_ptr, typename _Tp_ptr> 904 struct __sp_compatible_with 905 : false_type 906 { }; 907 908 template<typename _Yp, typename _Tp> 909 struct __sp_compatible_with<_Yp*, _Tp*> 910 : is_convertible<_Yp*, _Tp*>::type 911 { }; 912 913 template<typename _Up, size_t _Nm> 914 struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]> 915 : true_type 916 { }; 917 918 template<typename _Up, size_t _Nm> 919 struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]> 920 : true_type 921 { }; 922 923 template<typename _Up, size_t _Nm> 924 struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]> 925 : true_type 926 { }; 927 928 template<typename _Up, size_t _Nm> 929 struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]> 930 : true_type 931 { }; 932 933 // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N]. 934 template<typename _Up, size_t _Nm, typename _Yp, typename = void> 935 struct __sp_is_constructible_arrN 936 : false_type 937 { }; 938 939 template<typename _Up, size_t _Nm, typename _Yp> 940 struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>> 941 : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type 942 { }; 943 944 // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[]. 945 template<typename _Up, typename _Yp, typename = void> 946 struct __sp_is_constructible_arr 947 : false_type 948 { }; 949 950 template<typename _Up, typename _Yp> 951 struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>> 952 : is_convertible<_Yp(*)[], _Up(*)[]>::type 953 { }; 954 955 // Trait to check if shared_ptr<T> can be constructed from Y*. 956 template<typename _Tp, typename _Yp> 957 struct __sp_is_constructible; 958 959 // When T is U[N], Y(*)[N] shall be convertible to T*; 960 template<typename _Up, size_t _Nm, typename _Yp> 961 struct __sp_is_constructible<_Up[_Nm], _Yp> 962 : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type 963 { }; 964 965 // when T is U[], Y(*)[] shall be convertible to T*; 966 template<typename _Up, typename _Yp> 967 struct __sp_is_constructible<_Up[], _Yp> 968 : __sp_is_constructible_arr<_Up, _Yp>::type 969 { }; 970 971 // otherwise, Y* shall be convertible to T*. 972 template<typename _Tp, typename _Yp> 973 struct __sp_is_constructible 974 : is_convertible<_Yp*, _Tp*>::type 975 { }; 976 977 978 // Define operator* and operator-> for shared_ptr<T>. 979 template<typename _Tp, _Lock_policy _Lp, 980 bool = is_array<_Tp>::value, bool = is_void<_Tp>::value> 981 class __shared_ptr_access 982 { 983 public: 984 using element_type = _Tp; 985 986 element_type& 987 operator*() const noexcept 988 { 989 __glibcxx_assert(_M_get() != nullptr); 990 return *_M_get(); 991 } 992 993 element_type* 994 operator->() const noexcept 995 { 996 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); 997 return _M_get(); 998 } 999 1000 private: 1001 element_type* 1002 _M_get() const noexcept 1003 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } 1004 }; 1005 1006 // Define operator-> for shared_ptr<cv void>. 1007 template<typename _Tp, _Lock_policy _Lp> 1008 class __shared_ptr_access<_Tp, _Lp, false, true> 1009 { 1010 public: 1011 using element_type = _Tp; 1012 1013 element_type* 1014 operator->() const noexcept 1015 { 1016 auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); 1017 _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr); 1018 return __ptr; 1019 } 1020 }; 1021 1022 // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>. 1023 template<typename _Tp, _Lock_policy _Lp> 1024 class __shared_ptr_access<_Tp, _Lp, true, false> 1025 { 1026 public: 1027 using element_type = typename remove_extent<_Tp>::type; 1028 1029 #if __cplusplus <= 201402L 1030 [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]] 1031 element_type& 1032 operator*() const noexcept 1033 { 1034 __glibcxx_assert(_M_get() != nullptr); 1035 return *_M_get(); 1036 } 1037 1038 [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]] 1039 element_type* 1040 operator->() const noexcept 1041 { 1042 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); 1043 return _M_get(); 1044 } 1045 #endif 1046 1047 element_type& 1048 operator[](ptrdiff_t __i) const 1049 { 1050 __glibcxx_assert(_M_get() != nullptr); 1051 __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value); 1052 return _M_get()[__i]; 1053 } 1054 1055 private: 1056 element_type* 1057 _M_get() const noexcept 1058 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } 1059 }; 1060 1061 template<typename _Tp, _Lock_policy _Lp> 1062 class __shared_ptr 1063 : public __shared_ptr_access<_Tp, _Lp> 1064 { 1065 public: 1066 using element_type = typename remove_extent<_Tp>::type; 1067 1068 private: 1069 // Constraint for taking ownership of a pointer of type _Yp*: 1070 template<typename _Yp> 1071 using _SafeConv 1072 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type; 1073 1074 // Constraint for construction from shared_ptr and weak_ptr: 1075 template<typename _Yp, typename _Res = void> 1076 using _Compatible = typename 1077 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; 1078 1079 // Constraint for assignment from shared_ptr and weak_ptr: 1080 template<typename _Yp> 1081 using _Assignable = _Compatible<_Yp, __shared_ptr&>; 1082 1083 // Constraint for construction from unique_ptr: 1084 template<typename _Yp, typename _Del, typename _Res = void, 1085 typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer> 1086 using _UniqCompatible = typename enable_if<__and_< 1087 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*> 1088 >::value, _Res>::type; 1089 1090 // Constraint for assignment from unique_ptr: 1091 template<typename _Yp, typename _Del> 1092 using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>; 1093 1094 public: 1095 1096 #if __cplusplus > 201402L 1097 using weak_type = __weak_ptr<_Tp, _Lp>; 1098 #endif 1099 1100 constexpr __shared_ptr() noexcept 1101 : _M_ptr(0), _M_refcount() 1102 { } 1103 1104 template<typename _Yp, typename = _SafeConv<_Yp>> 1105 explicit 1106 __shared_ptr(_Yp* __p) 1107 : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type()) 1108 { 1109 static_assert( !is_void<_Yp>::value, "incomplete type" ); 1110 static_assert( sizeof(_Yp) > 0, "incomplete type" ); 1111 _M_enable_shared_from_this_with(__p); 1112 } 1113 1114 template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>> 1115 __shared_ptr(_Yp* __p, _Deleter __d) 1116 : _M_ptr(__p), _M_refcount(__p, std::move(__d)) 1117 { 1118 static_assert(__is_invocable<_Deleter&, _Yp*&>::value, 1119 "deleter expression d(p) is well-formed"); 1120 _M_enable_shared_from_this_with(__p); 1121 } 1122 1123 template<typename _Yp, typename _Deleter, typename _Alloc, 1124 typename = _SafeConv<_Yp>> 1125 __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) 1126 : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a)) 1127 { 1128 static_assert(__is_invocable<_Deleter&, _Yp*&>::value, 1129 "deleter expression d(p) is well-formed"); 1130 _M_enable_shared_from_this_with(__p); 1131 } 1132 1133 template<typename _Deleter> 1134 __shared_ptr(nullptr_t __p, _Deleter __d) 1135 : _M_ptr(0), _M_refcount(__p, std::move(__d)) 1136 { } 1137 1138 template<typename _Deleter, typename _Alloc> 1139 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 1140 : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a)) 1141 { } 1142 1143 template<typename _Yp> 1144 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r, 1145 element_type* __p) noexcept 1146 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 1147 { } 1148 1149 __shared_ptr(const __shared_ptr&) noexcept = default; 1150 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 1151 ~__shared_ptr() = default; 1152 1153 template<typename _Yp, typename = _Compatible<_Yp>> 1154 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1155 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1156 { } 1157 1158 __shared_ptr(__shared_ptr&& __r) noexcept 1159 : _M_ptr(__r._M_ptr), _M_refcount() 1160 { 1161 _M_refcount._M_swap(__r._M_refcount); 1162 __r._M_ptr = 0; 1163 } 1164 1165 template<typename _Yp, typename = _Compatible<_Yp>> 1166 __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept 1167 : _M_ptr(__r._M_ptr), _M_refcount() 1168 { 1169 _M_refcount._M_swap(__r._M_refcount); 1170 __r._M_ptr = 0; 1171 } 1172 1173 template<typename _Yp, typename = _Compatible<_Yp>> 1174 explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r) 1175 : _M_refcount(__r._M_refcount) // may throw 1176 { 1177 // It is now safe to copy __r._M_ptr, as 1178 // _M_refcount(__r._M_refcount) did not throw. 1179 _M_ptr = __r._M_ptr; 1180 } 1181 1182 // If an exception is thrown this constructor has no effect. 1183 template<typename _Yp, typename _Del, 1184 typename = _UniqCompatible<_Yp, _Del>> 1185 __shared_ptr(unique_ptr<_Yp, _Del>&& __r) 1186 : _M_ptr(__r.get()), _M_refcount() 1187 { 1188 auto __raw = __to_address(__r.get()); 1189 _M_refcount = __shared_count<_Lp>(std::move(__r)); 1190 _M_enable_shared_from_this_with(__raw); 1191 } 1192 1193 #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED 1194 protected: 1195 // If an exception is thrown this constructor has no effect. 1196 template<typename _Tp1, typename _Del, 1197 typename enable_if<__and_< 1198 __not_<is_array<_Tp>>, is_array<_Tp1>, 1199 is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*> 1200 >::value, bool>::type = true> 1201 __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete) 1202 : _M_ptr(__r.get()), _M_refcount() 1203 { 1204 auto __raw = __to_address(__r.get()); 1205 _M_refcount = __shared_count<_Lp>(std::move(__r)); 1206 _M_enable_shared_from_this_with(__raw); 1207 } 1208 public: 1209 #endif 1210 1211 #if _GLIBCXX_USE_DEPRECATED 1212 #pragma GCC diagnostic push 1213 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 1214 // Postcondition: use_count() == 1 and __r.get() == 0 1215 template<typename _Yp, typename = _Compatible<_Yp>> 1216 __shared_ptr(auto_ptr<_Yp>&& __r); 1217 #pragma GCC diagnostic pop 1218 #endif 1219 1220 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { } 1221 1222 template<typename _Yp> 1223 _Assignable<_Yp> 1224 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1225 { 1226 _M_ptr = __r._M_ptr; 1227 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 1228 return *this; 1229 } 1230 1231 #if _GLIBCXX_USE_DEPRECATED 1232 #pragma GCC diagnostic push 1233 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 1234 template<typename _Yp> 1235 _Assignable<_Yp> 1236 operator=(auto_ptr<_Yp>&& __r) 1237 { 1238 __shared_ptr(std::move(__r)).swap(*this); 1239 return *this; 1240 } 1241 #pragma GCC diagnostic pop 1242 #endif 1243 1244 __shared_ptr& 1245 operator=(__shared_ptr&& __r) noexcept 1246 { 1247 __shared_ptr(std::move(__r)).swap(*this); 1248 return *this; 1249 } 1250 1251 template<class _Yp> 1252 _Assignable<_Yp> 1253 operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept 1254 { 1255 __shared_ptr(std::move(__r)).swap(*this); 1256 return *this; 1257 } 1258 1259 template<typename _Yp, typename _Del> 1260 _UniqAssignable<_Yp, _Del> 1261 operator=(unique_ptr<_Yp, _Del>&& __r) 1262 { 1263 __shared_ptr(std::move(__r)).swap(*this); 1264 return *this; 1265 } 1266 1267 void 1268 reset() noexcept 1269 { __shared_ptr().swap(*this); } 1270 1271 template<typename _Yp> 1272 _SafeConv<_Yp> 1273 reset(_Yp* __p) // _Yp must be complete. 1274 { 1275 // Catch self-reset errors. 1276 __glibcxx_assert(__p == 0 || __p != _M_ptr); 1277 __shared_ptr(__p).swap(*this); 1278 } 1279 1280 template<typename _Yp, typename _Deleter> 1281 _SafeConv<_Yp> 1282 reset(_Yp* __p, _Deleter __d) 1283 { __shared_ptr(__p, std::move(__d)).swap(*this); } 1284 1285 template<typename _Yp, typename _Deleter, typename _Alloc> 1286 _SafeConv<_Yp> 1287 reset(_Yp* __p, _Deleter __d, _Alloc __a) 1288 { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); } 1289 1290 element_type* 1291 get() const noexcept 1292 { return _M_ptr; } 1293 1294 explicit operator bool() const // never throws 1295 { return _M_ptr == 0 ? false : true; } 1296 1297 bool 1298 unique() const noexcept 1299 { return _M_refcount._M_unique(); } 1300 1301 long 1302 use_count() const noexcept 1303 { return _M_refcount._M_get_use_count(); } 1304 1305 void 1306 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 1307 { 1308 std::swap(_M_ptr, __other._M_ptr); 1309 _M_refcount._M_swap(__other._M_refcount); 1310 } 1311 1312 template<typename _Tp1> 1313 bool 1314 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1315 { return _M_refcount._M_less(__rhs._M_refcount); } 1316 1317 template<typename _Tp1> 1318 bool 1319 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1320 { return _M_refcount._M_less(__rhs._M_refcount); } 1321 1322 protected: 1323 // This constructor is non-standard, it is used by allocate_shared. 1324 template<typename _Alloc, typename... _Args> 1325 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1326 _Args&&... __args) 1327 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 1328 std::forward<_Args>(__args)...) 1329 { 1330 // _M_ptr needs to point to the newly constructed object. 1331 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 1332 #if __cpp_rtti 1333 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 1334 #else 1335 void* __p = _M_refcount._M_get_deleter(_Sp_make_shared_tag::_S_ti()); 1336 #endif 1337 _M_ptr = static_cast<_Tp*>(__p); 1338 _M_enable_shared_from_this_with(_M_ptr); 1339 } 1340 1341 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1342 typename... _Args> 1343 friend __shared_ptr<_Tp1, _Lp1> 1344 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1345 1346 // This constructor is used by __weak_ptr::lock() and 1347 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t). 1348 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t) 1349 : _M_refcount(__r._M_refcount, std::nothrow) 1350 { 1351 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr; 1352 } 1353 1354 friend class __weak_ptr<_Tp, _Lp>; 1355 1356 private: 1357 1358 template<typename _Yp> 1359 using __esft_base_t = decltype(__enable_shared_from_this_base( 1360 std::declval<const __shared_count<_Lp>&>(), 1361 std::declval<_Yp*>())); 1362 1363 // Detect an accessible and unambiguous enable_shared_from_this base. 1364 template<typename _Yp, typename = void> 1365 struct __has_esft_base 1366 : false_type { }; 1367 1368 template<typename _Yp> 1369 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>> 1370 : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays 1371 1372 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> 1373 typename enable_if<__has_esft_base<_Yp2>::value>::type 1374 _M_enable_shared_from_this_with(_Yp* __p) noexcept 1375 { 1376 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p)) 1377 __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount); 1378 } 1379 1380 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> 1381 typename enable_if<!__has_esft_base<_Yp2>::value>::type 1382 _M_enable_shared_from_this_with(_Yp*) noexcept 1383 { } 1384 1385 void* 1386 _M_get_deleter(const std::type_info& __ti) const noexcept 1387 { return _M_refcount._M_get_deleter(__ti); } 1388 1389 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1390 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1391 1392 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1393 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 1394 1395 template<typename _Del, typename _Tp1> 1396 friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept; 1397 1398 element_type* _M_ptr; // Contained pointer. 1399 __shared_count<_Lp> _M_refcount; // Reference counter. 1400 }; 1401 1402 1403 // 20.7.2.2.7 shared_ptr comparisons 1404 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1405 inline bool 1406 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1407 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1408 { return __a.get() == __b.get(); } 1409 1410 template<typename _Tp, _Lock_policy _Lp> 1411 inline bool 1412 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1413 { return !__a; } 1414 1415 template<typename _Tp, _Lock_policy _Lp> 1416 inline bool 1417 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1418 { return !__a; } 1419 1420 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1421 inline bool 1422 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1423 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1424 { return __a.get() != __b.get(); } 1425 1426 template<typename _Tp, _Lock_policy _Lp> 1427 inline bool 1428 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1429 { return (bool)__a; } 1430 1431 template<typename _Tp, _Lock_policy _Lp> 1432 inline bool 1433 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1434 { return (bool)__a; } 1435 1436 template<typename _Tp, typename _Up, _Lock_policy _Lp> 1437 inline bool 1438 operator<(const __shared_ptr<_Tp, _Lp>& __a, 1439 const __shared_ptr<_Up, _Lp>& __b) noexcept 1440 { 1441 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1442 using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type; 1443 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; 1444 return less<_Vp>()(__a.get(), __b.get()); 1445 } 1446 1447 template<typename _Tp, _Lock_policy _Lp> 1448 inline bool 1449 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1450 { 1451 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1452 return less<_Tp_elt*>()(__a.get(), nullptr); 1453 } 1454 1455 template<typename _Tp, _Lock_policy _Lp> 1456 inline bool 1457 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1458 { 1459 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1460 return less<_Tp_elt*>()(nullptr, __a.get()); 1461 } 1462 1463 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1464 inline bool 1465 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 1466 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1467 { return !(__b < __a); } 1468 1469 template<typename _Tp, _Lock_policy _Lp> 1470 inline bool 1471 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1472 { return !(nullptr < __a); } 1473 1474 template<typename _Tp, _Lock_policy _Lp> 1475 inline bool 1476 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1477 { return !(__a < nullptr); } 1478 1479 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1480 inline bool 1481 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 1482 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1483 { return (__b < __a); } 1484 1485 template<typename _Tp, _Lock_policy _Lp> 1486 inline bool 1487 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1488 { return nullptr < __a; } 1489 1490 template<typename _Tp, _Lock_policy _Lp> 1491 inline bool 1492 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1493 { return __a < nullptr; } 1494 1495 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1496 inline bool 1497 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 1498 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1499 { return !(__a < __b); } 1500 1501 template<typename _Tp, _Lock_policy _Lp> 1502 inline bool 1503 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1504 { return !(__a < nullptr); } 1505 1506 template<typename _Tp, _Lock_policy _Lp> 1507 inline bool 1508 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1509 { return !(nullptr < __a); } 1510 1511 template<typename _Sp> 1512 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1513 { 1514 bool 1515 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 1516 { 1517 typedef typename _Sp::element_type element_type; 1518 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1519 } 1520 }; 1521 1522 template<typename _Tp, _Lock_policy _Lp> 1523 struct less<__shared_ptr<_Tp, _Lp>> 1524 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1525 { }; 1526 1527 // 20.7.2.2.8 shared_ptr specialized algorithms. 1528 template<typename _Tp, _Lock_policy _Lp> 1529 inline void 1530 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 1531 { __a.swap(__b); } 1532 1533 // 20.7.2.2.9 shared_ptr casts 1534 1535 // The seemingly equivalent code: 1536 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1537 // will eventually result in undefined behaviour, attempting to 1538 // delete the same object twice. 1539 /// static_pointer_cast 1540 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1541 inline __shared_ptr<_Tp, _Lp> 1542 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1543 { 1544 using _Sp = __shared_ptr<_Tp, _Lp>; 1545 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); 1546 } 1547 1548 // The seemingly equivalent code: 1549 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1550 // will eventually result in undefined behaviour, attempting to 1551 // delete the same object twice. 1552 /// const_pointer_cast 1553 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1554 inline __shared_ptr<_Tp, _Lp> 1555 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1556 { 1557 using _Sp = __shared_ptr<_Tp, _Lp>; 1558 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); 1559 } 1560 1561 // The seemingly equivalent code: 1562 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1563 // will eventually result in undefined behaviour, attempting to 1564 // delete the same object twice. 1565 /// dynamic_pointer_cast 1566 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1567 inline __shared_ptr<_Tp, _Lp> 1568 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1569 { 1570 using _Sp = __shared_ptr<_Tp, _Lp>; 1571 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) 1572 return _Sp(__r, __p); 1573 return _Sp(); 1574 } 1575 1576 #if __cplusplus > 201402L 1577 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1578 inline __shared_ptr<_Tp, _Lp> 1579 reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1580 { 1581 using _Sp = __shared_ptr<_Tp, _Lp>; 1582 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); 1583 } 1584 #endif 1585 1586 template<typename _Tp, _Lock_policy _Lp> 1587 class __weak_ptr 1588 { 1589 template<typename _Yp, typename _Res = void> 1590 using _Compatible = typename 1591 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; 1592 1593 // Constraint for assignment from shared_ptr and weak_ptr: 1594 template<typename _Yp> 1595 using _Assignable = _Compatible<_Yp, __weak_ptr&>; 1596 1597 public: 1598 using element_type = typename remove_extent<_Tp>::type; 1599 1600 constexpr __weak_ptr() noexcept 1601 : _M_ptr(nullptr), _M_refcount() 1602 { } 1603 1604 __weak_ptr(const __weak_ptr&) noexcept = default; 1605 1606 ~__weak_ptr() = default; 1607 1608 // The "obvious" converting constructor implementation: 1609 // 1610 // template<typename _Tp1> 1611 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1612 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1613 // { } 1614 // 1615 // has a serious problem. 1616 // 1617 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1618 // conversion may require access to *__r._M_ptr (virtual inheritance). 1619 // 1620 // It is not possible to avoid spurious access violations since 1621 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1622 template<typename _Yp, typename = _Compatible<_Yp>> 1623 __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept 1624 : _M_refcount(__r._M_refcount) 1625 { _M_ptr = __r.lock().get(); } 1626 1627 template<typename _Yp, typename = _Compatible<_Yp>> 1628 __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1629 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1630 { } 1631 1632 __weak_ptr(__weak_ptr&& __r) noexcept 1633 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount)) 1634 { __r._M_ptr = nullptr; } 1635 1636 template<typename _Yp, typename = _Compatible<_Yp>> 1637 __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept 1638 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount)) 1639 { __r._M_ptr = nullptr; } 1640 1641 __weak_ptr& 1642 operator=(const __weak_ptr& __r) noexcept = default; 1643 1644 template<typename _Yp> 1645 _Assignable<_Yp> 1646 operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept 1647 { 1648 _M_ptr = __r.lock().get(); 1649 _M_refcount = __r._M_refcount; 1650 return *this; 1651 } 1652 1653 template<typename _Yp> 1654 _Assignable<_Yp> 1655 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1656 { 1657 _M_ptr = __r._M_ptr; 1658 _M_refcount = __r._M_refcount; 1659 return *this; 1660 } 1661 1662 __weak_ptr& 1663 operator=(__weak_ptr&& __r) noexcept 1664 { 1665 _M_ptr = __r._M_ptr; 1666 _M_refcount = std::move(__r._M_refcount); 1667 __r._M_ptr = nullptr; 1668 return *this; 1669 } 1670 1671 template<typename _Yp> 1672 _Assignable<_Yp> 1673 operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept 1674 { 1675 _M_ptr = __r.lock().get(); 1676 _M_refcount = std::move(__r._M_refcount); 1677 __r._M_ptr = nullptr; 1678 return *this; 1679 } 1680 1681 __shared_ptr<_Tp, _Lp> 1682 lock() const noexcept 1683 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); } 1684 1685 long 1686 use_count() const noexcept 1687 { return _M_refcount._M_get_use_count(); } 1688 1689 bool 1690 expired() const noexcept 1691 { return _M_refcount._M_get_use_count() == 0; } 1692 1693 template<typename _Tp1> 1694 bool 1695 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept 1696 { return _M_refcount._M_less(__rhs._M_refcount); } 1697 1698 template<typename _Tp1> 1699 bool 1700 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept 1701 { return _M_refcount._M_less(__rhs._M_refcount); } 1702 1703 void 1704 reset() noexcept 1705 { __weak_ptr().swap(*this); } 1706 1707 void 1708 swap(__weak_ptr& __s) noexcept 1709 { 1710 std::swap(_M_ptr, __s._M_ptr); 1711 _M_refcount._M_swap(__s._M_refcount); 1712 } 1713 1714 private: 1715 // Used by __enable_shared_from_this. 1716 void 1717 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 1718 { 1719 if (use_count() == 0) 1720 { 1721 _M_ptr = __ptr; 1722 _M_refcount = __refcount; 1723 } 1724 } 1725 1726 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1727 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1728 friend class __enable_shared_from_this<_Tp, _Lp>; 1729 friend class enable_shared_from_this<_Tp>; 1730 1731 element_type* _M_ptr; // Contained pointer. 1732 __weak_count<_Lp> _M_refcount; // Reference counter. 1733 }; 1734 1735 // 20.7.2.3.6 weak_ptr specialized algorithms. 1736 template<typename _Tp, _Lock_policy _Lp> 1737 inline void 1738 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 1739 { __a.swap(__b); } 1740 1741 template<typename _Tp, typename _Tp1> 1742 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1743 { 1744 bool 1745 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept 1746 { return __lhs.owner_before(__rhs); } 1747 1748 bool 1749 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept 1750 { return __lhs.owner_before(__rhs); } 1751 1752 bool 1753 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept 1754 { return __lhs.owner_before(__rhs); } 1755 }; 1756 1757 template<> 1758 struct _Sp_owner_less<void, void> 1759 { 1760 template<typename _Tp, typename _Up> 1761 auto 1762 operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept 1763 -> decltype(__lhs.owner_before(__rhs)) 1764 { return __lhs.owner_before(__rhs); } 1765 1766 using is_transparent = void; 1767 }; 1768 1769 template<typename _Tp, _Lock_policy _Lp> 1770 struct owner_less<__shared_ptr<_Tp, _Lp>> 1771 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1772 { }; 1773 1774 template<typename _Tp, _Lock_policy _Lp> 1775 struct owner_less<__weak_ptr<_Tp, _Lp>> 1776 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1777 { }; 1778 1779 1780 template<typename _Tp, _Lock_policy _Lp> 1781 class __enable_shared_from_this 1782 { 1783 protected: 1784 constexpr __enable_shared_from_this() noexcept { } 1785 1786 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 1787 1788 __enable_shared_from_this& 1789 operator=(const __enable_shared_from_this&) noexcept 1790 { return *this; } 1791 1792 ~__enable_shared_from_this() { } 1793 1794 public: 1795 __shared_ptr<_Tp, _Lp> 1796 shared_from_this() 1797 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1798 1799 __shared_ptr<const _Tp, _Lp> 1800 shared_from_this() const 1801 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1802 1803 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 1804 __weak_ptr<_Tp, _Lp> 1805 weak_from_this() noexcept 1806 { return this->_M_weak_this; } 1807 1808 __weak_ptr<const _Tp, _Lp> 1809 weak_from_this() const noexcept 1810 { return this->_M_weak_this; } 1811 #endif 1812 1813 private: 1814 template<typename _Tp1> 1815 void 1816 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 1817 { _M_weak_this._M_assign(__p, __n); } 1818 1819 friend const __enable_shared_from_this* 1820 __enable_shared_from_this_base(const __shared_count<_Lp>&, 1821 const __enable_shared_from_this* __p) 1822 { return __p; } 1823 1824 template<typename, _Lock_policy> 1825 friend class __shared_ptr; 1826 1827 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1828 }; 1829 1830 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1831 inline __shared_ptr<_Tp, _Lp> 1832 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1833 { 1834 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1835 std::forward<_Args>(__args)...); 1836 } 1837 1838 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1839 inline __shared_ptr<_Tp, _Lp> 1840 __make_shared(_Args&&... __args) 1841 { 1842 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1843 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1844 std::forward<_Args>(__args)...); 1845 } 1846 1847 /// std::hash specialization for __shared_ptr. 1848 template<typename _Tp, _Lock_policy _Lp> 1849 struct hash<__shared_ptr<_Tp, _Lp>> 1850 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 1851 { 1852 size_t 1853 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1854 { 1855 return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()( 1856 __s.get()); 1857 } 1858 }; 1859 1860 _GLIBCXX_END_NAMESPACE_VERSION 1861 } // namespace 1862 1863 #endif // _SHARED_PTR_BASE_H 1864