1 // shared_ptr and weak_ptr implementation details -*- C++ -*- 2 3 // Copyright (C) 2007-2017 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 _GLIBCXX_BEGIN_NAMESPACE_VERSION 63 64 #if _GLIBCXX_USE_DEPRECATED 65 template<typename> class auto_ptr; 66 #endif 67 68 /** 69 * @brief Exception possibly thrown by @c shared_ptr. 70 * @ingroup exceptions 71 */ 72 class bad_weak_ptr : public std::exception 73 { 74 public: 75 virtual char const* what() const noexcept; 76 77 virtual ~bad_weak_ptr() noexcept; 78 }; 79 80 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 81 inline void 82 __throw_bad_weak_ptr() 83 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } 84 85 using __gnu_cxx::_Lock_policy; 86 using __gnu_cxx::__default_lock_policy; 87 using __gnu_cxx::_S_single; 88 using __gnu_cxx::_S_mutex; 89 using __gnu_cxx::_S_atomic; 90 91 // Empty helper class except when the template argument is _S_mutex. 92 template<_Lock_policy _Lp> 93 class _Mutex_base 94 { 95 protected: 96 // The atomic policy uses fully-fenced builtins, single doesn't care. 97 enum { _S_need_barriers = 0 }; 98 }; 99 100 template<> 101 class _Mutex_base<_S_mutex> 102 : public __gnu_cxx::__mutex 103 { 104 protected: 105 // This policy is used when atomic builtins are not available. 106 // The replacement atomic operations might not have the necessary 107 // memory barriers. 108 enum { _S_need_barriers = 1 }; 109 }; 110 111 template<_Lock_policy _Lp = __default_lock_policy> 112 class _Sp_counted_base 113 : public _Mutex_base<_Lp> 114 { 115 public: 116 _Sp_counted_base() noexcept 117 : _M_use_count(1), _M_weak_count(1) { } 118 119 virtual 120 ~_Sp_counted_base() noexcept 121 { } 122 123 // Called when _M_use_count drops to zero, to release the resources 124 // managed by *this. 125 virtual void 126 _M_dispose() noexcept = 0; 127 128 // Called when _M_weak_count drops to zero. 129 virtual void 130 _M_destroy() noexcept 131 { delete this; } 132 133 virtual void* 134 _M_get_deleter(const std::type_info&) noexcept = 0; 135 136 void 137 _M_add_ref_copy() 138 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 139 140 void 141 _M_add_ref_lock(); 142 143 bool 144 _M_add_ref_lock_nothrow(); 145 146 void 147 _M_release() noexcept 148 { 149 // Be race-detector-friendly. For more info see bits/c++config. 150 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 151 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 152 { 153 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 154 _M_dispose(); 155 // There must be a memory barrier between dispose() and destroy() 156 // to ensure that the effects of dispose() are observed in the 157 // thread that runs destroy(). 158 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 159 if (_Mutex_base<_Lp>::_S_need_barriers) 160 { 161 __atomic_thread_fence (__ATOMIC_ACQ_REL); 162 } 163 164 // Be race-detector-friendly. For more info see bits/c++config. 165 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 166 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 167 -1) == 1) 168 { 169 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 170 _M_destroy(); 171 } 172 } 173 } 174 175 void 176 _M_weak_add_ref() noexcept 177 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 178 179 void 180 _M_weak_release() noexcept 181 { 182 // Be race-detector-friendly. For more info see bits/c++config. 183 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 184 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 185 { 186 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 187 if (_Mutex_base<_Lp>::_S_need_barriers) 188 { 189 // See _M_release(), 190 // destroy() must observe results of dispose() 191 __atomic_thread_fence (__ATOMIC_ACQ_REL); 192 } 193 _M_destroy(); 194 } 195 } 196 197 long 198 _M_get_use_count() const noexcept 199 { 200 // No memory barrier is used here so there is no synchronization 201 // with other threads. 202 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); 203 } 204 205 private: 206 _Sp_counted_base(_Sp_counted_base const&) = delete; 207 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; 208 209 _Atomic_word _M_use_count; // #shared 210 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 211 }; 212 213 template<> 214 inline void 215 _Sp_counted_base<_S_single>:: 216 _M_add_ref_lock() 217 { 218 if (_M_use_count == 0) 219 __throw_bad_weak_ptr(); 220 ++_M_use_count; 221 } 222 223 template<> 224 inline void 225 _Sp_counted_base<_S_mutex>:: 226 _M_add_ref_lock() 227 { 228 __gnu_cxx::__scoped_lock sentry(*this); 229 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 230 { 231 _M_use_count = 0; 232 __throw_bad_weak_ptr(); 233 } 234 } 235 236 template<> 237 inline void 238 _Sp_counted_base<_S_atomic>:: 239 _M_add_ref_lock() 240 { 241 // Perform lock-free add-if-not-zero operation. 242 _Atomic_word __count = _M_get_use_count(); 243 do 244 { 245 if (__count == 0) 246 __throw_bad_weak_ptr(); 247 // Replace the current counter value with the old value + 1, as 248 // long as it's not changed meanwhile. 249 } 250 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 251 true, __ATOMIC_ACQ_REL, 252 __ATOMIC_RELAXED)); 253 } 254 255 template<> 256 inline bool 257 _Sp_counted_base<_S_single>:: 258 _M_add_ref_lock_nothrow() 259 { 260 if (_M_use_count == 0) 261 return false; 262 ++_M_use_count; 263 return true; 264 } 265 266 template<> 267 inline bool 268 _Sp_counted_base<_S_mutex>:: 269 _M_add_ref_lock_nothrow() 270 { 271 __gnu_cxx::__scoped_lock sentry(*this); 272 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 273 { 274 _M_use_count = 0; 275 return false; 276 } 277 return true; 278 } 279 280 template<> 281 inline bool 282 _Sp_counted_base<_S_atomic>:: 283 _M_add_ref_lock_nothrow() 284 { 285 // Perform lock-free add-if-not-zero operation. 286 _Atomic_word __count = _M_get_use_count(); 287 do 288 { 289 if (__count == 0) 290 return false; 291 // Replace the current counter value with the old value + 1, as 292 // long as it's not changed meanwhile. 293 } 294 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 295 true, __ATOMIC_ACQ_REL, 296 __ATOMIC_RELAXED)); 297 return true; 298 } 299 300 template<> 301 inline void 302 _Sp_counted_base<_S_single>::_M_add_ref_copy() 303 { ++_M_use_count; } 304 305 template<> 306 inline void 307 _Sp_counted_base<_S_single>::_M_release() noexcept 308 { 309 if (--_M_use_count == 0) 310 { 311 _M_dispose(); 312 if (--_M_weak_count == 0) 313 _M_destroy(); 314 } 315 } 316 317 template<> 318 inline void 319 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept 320 { ++_M_weak_count; } 321 322 template<> 323 inline void 324 _Sp_counted_base<_S_single>::_M_weak_release() noexcept 325 { 326 if (--_M_weak_count == 0) 327 _M_destroy(); 328 } 329 330 template<> 331 inline long 332 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept 333 { return _M_use_count; } 334 335 336 // Forward declarations. 337 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 338 class __shared_ptr; 339 340 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 341 class __weak_ptr; 342 343 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 344 class __enable_shared_from_this; 345 346 template<typename _Tp> 347 class shared_ptr; 348 349 template<typename _Tp> 350 class weak_ptr; 351 352 template<typename _Tp> 353 struct owner_less; 354 355 template<typename _Tp> 356 class enable_shared_from_this; 357 358 template<_Lock_policy _Lp = __default_lock_policy> 359 class __weak_count; 360 361 template<_Lock_policy _Lp = __default_lock_policy> 362 class __shared_count; 363 364 365 // Counted ptr with no deleter or allocator support 366 template<typename _Ptr, _Lock_policy _Lp> 367 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> 368 { 369 public: 370 explicit 371 _Sp_counted_ptr(_Ptr __p) noexcept 372 : _M_ptr(__p) { } 373 374 virtual void 375 _M_dispose() noexcept 376 { delete _M_ptr; } 377 378 virtual void 379 _M_destroy() noexcept 380 { delete this; } 381 382 virtual void* 383 _M_get_deleter(const std::type_info&) noexcept 384 { return nullptr; } 385 386 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 387 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 388 389 private: 390 _Ptr _M_ptr; 391 }; 392 393 template<> 394 inline void 395 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } 396 397 template<> 398 inline void 399 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } 400 401 template<> 402 inline void 403 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } 404 405 template<int _Nm, typename _Tp, 406 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)> 407 struct _Sp_ebo_helper; 408 409 /// Specialization using EBO. 410 template<int _Nm, typename _Tp> 411 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp 412 { 413 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { } 414 explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { } 415 416 static _Tp& 417 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); } 418 }; 419 420 /// Specialization not using EBO. 421 template<int _Nm, typename _Tp> 422 struct _Sp_ebo_helper<_Nm, _Tp, false> 423 { 424 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { } 425 explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { } 426 427 static _Tp& 428 _S_get(_Sp_ebo_helper& __eboh) 429 { return __eboh._M_tp; } 430 431 private: 432 _Tp _M_tp; 433 }; 434 435 // Support for custom deleter and/or allocator 436 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 437 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> 438 { 439 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc> 440 { 441 typedef _Sp_ebo_helper<0, _Deleter> _Del_base; 442 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base; 443 444 public: 445 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 446 : _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a) 447 { } 448 449 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); } 450 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); } 451 452 _Ptr _M_ptr; 453 }; 454 455 public: 456 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>; 457 458 // __d(__p) must not throw. 459 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept 460 : _M_impl(__p, std::move(__d), _Alloc()) { } 461 462 // __d(__p) must not throw. 463 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 464 : _M_impl(__p, std::move(__d), __a) { } 465 466 ~_Sp_counted_deleter() noexcept { } 467 468 virtual void 469 _M_dispose() noexcept 470 { _M_impl._M_del()(_M_impl._M_ptr); } 471 472 virtual void 473 _M_destroy() noexcept 474 { 475 __allocator_type __a(_M_impl._M_alloc()); 476 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 477 this->~_Sp_counted_deleter(); 478 } 479 480 virtual void* 481 _M_get_deleter(const std::type_info& __ti) noexcept 482 { 483 #if __cpp_rtti 484 // _GLIBCXX_RESOLVE_LIB_DEFECTS 485 // 2400. shared_ptr's get_deleter() should use addressof() 486 return __ti == typeid(_Deleter) 487 ? std::__addressof(_M_impl._M_del()) 488 : nullptr; 489 #else 490 return nullptr; 491 #endif 492 } 493 494 private: 495 _Impl _M_impl; 496 }; 497 498 // helpers for make_shared / allocate_shared 499 500 struct _Sp_make_shared_tag { }; 501 502 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 503 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> 504 { 505 class _Impl : _Sp_ebo_helper<0, _Alloc> 506 { 507 typedef _Sp_ebo_helper<0, _Alloc> _A_base; 508 509 public: 510 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { } 511 512 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); } 513 514 __gnu_cxx::__aligned_buffer<_Tp> _M_storage; 515 }; 516 517 public: 518 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>; 519 520 template<typename... _Args> 521 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 522 : _M_impl(__a) 523 { 524 // _GLIBCXX_RESOLVE_LIB_DEFECTS 525 // 2070. allocate_shared should use allocator_traits<A>::construct 526 allocator_traits<_Alloc>::construct(__a, _M_ptr(), 527 std::forward<_Args>(__args)...); // might throw 528 } 529 530 ~_Sp_counted_ptr_inplace() noexcept { } 531 532 virtual void 533 _M_dispose() noexcept 534 { 535 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr()); 536 } 537 538 // Override because the allocator needs to know the dynamic type 539 virtual void 540 _M_destroy() noexcept 541 { 542 __allocator_type __a(_M_impl._M_alloc()); 543 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 544 this->~_Sp_counted_ptr_inplace(); 545 } 546 547 // Sneaky trick so __shared_ptr can get the managed pointer 548 virtual void* 549 _M_get_deleter(const std::type_info& __ti) noexcept 550 { 551 #if __cpp_rtti 552 if (__ti == typeid(_Sp_make_shared_tag)) 553 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr()); 554 #endif 555 return nullptr; 556 } 557 558 private: 559 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); } 560 561 _Impl _M_impl; 562 }; 563 564 // The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>. 565 struct __sp_array_delete 566 { 567 template<typename _Yp> 568 void operator()(_Yp* __p) const { delete[] __p; } 569 }; 570 571 template<_Lock_policy _Lp> 572 class __shared_count 573 { 574 public: 575 constexpr __shared_count() noexcept : _M_pi(0) 576 { } 577 578 template<typename _Ptr> 579 explicit 580 __shared_count(_Ptr __p) : _M_pi(0) 581 { 582 __try 583 { 584 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 585 } 586 __catch(...) 587 { 588 delete __p; 589 __throw_exception_again; 590 } 591 } 592 593 template<typename _Ptr> 594 __shared_count(_Ptr __p, /* is_array = */ false_type) 595 : __shared_count(__p) 596 { } 597 598 template<typename _Ptr> 599 __shared_count(_Ptr __p, /* is_array = */ true_type) 600 : __shared_count(__p, __sp_array_delete{}, allocator<void>()) 601 { } 602 603 template<typename _Ptr, typename _Deleter> 604 __shared_count(_Ptr __p, _Deleter __d) 605 : __shared_count(__p, std::move(__d), allocator<void>()) 606 { } 607 608 template<typename _Ptr, typename _Deleter, typename _Alloc> 609 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 610 { 611 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 612 __try 613 { 614 typename _Sp_cd_type::__allocator_type __a2(__a); 615 auto __guard = std::__allocate_guarded(__a2); 616 _Sp_cd_type* __mem = __guard.get(); 617 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a)); 618 _M_pi = __mem; 619 __guard = nullptr; 620 } 621 __catch(...) 622 { 623 __d(__p); // Call _Deleter on __p. 624 __throw_exception_again; 625 } 626 } 627 628 template<typename _Tp, typename _Alloc, typename... _Args> 629 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 630 _Args&&... __args) 631 : _M_pi(0) 632 { 633 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 634 typename _Sp_cp_type::__allocator_type __a2(__a); 635 auto __guard = std::__allocate_guarded(__a2); 636 _Sp_cp_type* __mem = __guard.get(); 637 ::new (__mem) _Sp_cp_type(std::move(__a), 638 std::forward<_Args>(__args)...); 639 _M_pi = __mem; 640 __guard = nullptr; 641 } 642 643 #if _GLIBCXX_USE_DEPRECATED 644 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 645 template<typename _Tp> 646 explicit 647 __shared_count(std::auto_ptr<_Tp>&& __r); 648 #endif 649 650 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 651 template<typename _Tp, typename _Del> 652 explicit 653 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0) 654 { 655 // _GLIBCXX_RESOLVE_LIB_DEFECTS 656 // 2415. Inconsistency between unique_ptr and shared_ptr 657 if (__r.get() == nullptr) 658 return; 659 660 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer; 661 using _Del2 = typename conditional<is_reference<_Del>::value, 662 reference_wrapper<typename remove_reference<_Del>::type>, 663 _Del>::type; 664 using _Sp_cd_type 665 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>; 666 using _Alloc = allocator<_Sp_cd_type>; 667 using _Alloc_traits = allocator_traits<_Alloc>; 668 _Alloc __a; 669 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1); 670 _Alloc_traits::construct(__a, __mem, __r.release(), 671 __r.get_deleter()); // non-throwing 672 _M_pi = __mem; 673 } 674 675 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 676 explicit __shared_count(const __weak_count<_Lp>& __r); 677 678 // Does not throw if __r._M_get_use_count() == 0, caller must check. 679 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t); 680 681 ~__shared_count() noexcept 682 { 683 if (_M_pi != nullptr) 684 _M_pi->_M_release(); 685 } 686 687 __shared_count(const __shared_count& __r) noexcept 688 : _M_pi(__r._M_pi) 689 { 690 if (_M_pi != 0) 691 _M_pi->_M_add_ref_copy(); 692 } 693 694 __shared_count& 695 operator=(const __shared_count& __r) noexcept 696 { 697 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 698 if (__tmp != _M_pi) 699 { 700 if (__tmp != 0) 701 __tmp->_M_add_ref_copy(); 702 if (_M_pi != 0) 703 _M_pi->_M_release(); 704 _M_pi = __tmp; 705 } 706 return *this; 707 } 708 709 void 710 _M_swap(__shared_count& __r) noexcept 711 { 712 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 713 __r._M_pi = _M_pi; 714 _M_pi = __tmp; 715 } 716 717 long 718 _M_get_use_count() const noexcept 719 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 720 721 bool 722 _M_unique() const noexcept 723 { return this->_M_get_use_count() == 1; } 724 725 void* 726 _M_get_deleter(const std::type_info& __ti) const noexcept 727 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; } 728 729 bool 730 _M_less(const __shared_count& __rhs) const noexcept 731 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 732 733 bool 734 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 735 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 736 737 // Friend function injected into enclosing namespace and found by ADL 738 friend inline bool 739 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 740 { return __a._M_pi == __b._M_pi; } 741 742 private: 743 friend class __weak_count<_Lp>; 744 745 _Sp_counted_base<_Lp>* _M_pi; 746 }; 747 748 749 template<_Lock_policy _Lp> 750 class __weak_count 751 { 752 public: 753 constexpr __weak_count() noexcept : _M_pi(nullptr) 754 { } 755 756 __weak_count(const __shared_count<_Lp>& __r) noexcept 757 : _M_pi(__r._M_pi) 758 { 759 if (_M_pi != nullptr) 760 _M_pi->_M_weak_add_ref(); 761 } 762 763 __weak_count(const __weak_count& __r) noexcept 764 : _M_pi(__r._M_pi) 765 { 766 if (_M_pi != nullptr) 767 _M_pi->_M_weak_add_ref(); 768 } 769 770 __weak_count(__weak_count&& __r) noexcept 771 : _M_pi(__r._M_pi) 772 { __r._M_pi = nullptr; } 773 774 ~__weak_count() noexcept 775 { 776 if (_M_pi != nullptr) 777 _M_pi->_M_weak_release(); 778 } 779 780 __weak_count& 781 operator=(const __shared_count<_Lp>& __r) noexcept 782 { 783 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 784 if (__tmp != nullptr) 785 __tmp->_M_weak_add_ref(); 786 if (_M_pi != nullptr) 787 _M_pi->_M_weak_release(); 788 _M_pi = __tmp; 789 return *this; 790 } 791 792 __weak_count& 793 operator=(const __weak_count& __r) noexcept 794 { 795 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 796 if (__tmp != nullptr) 797 __tmp->_M_weak_add_ref(); 798 if (_M_pi != nullptr) 799 _M_pi->_M_weak_release(); 800 _M_pi = __tmp; 801 return *this; 802 } 803 804 __weak_count& 805 operator=(__weak_count&& __r) noexcept 806 { 807 if (_M_pi != nullptr) 808 _M_pi->_M_weak_release(); 809 _M_pi = __r._M_pi; 810 __r._M_pi = nullptr; 811 return *this; 812 } 813 814 void 815 _M_swap(__weak_count& __r) noexcept 816 { 817 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 818 __r._M_pi = _M_pi; 819 _M_pi = __tmp; 820 } 821 822 long 823 _M_get_use_count() const noexcept 824 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; } 825 826 bool 827 _M_less(const __weak_count& __rhs) const noexcept 828 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 829 830 bool 831 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 832 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 833 834 // Friend function injected into enclosing namespace and found by ADL 835 friend inline bool 836 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 837 { return __a._M_pi == __b._M_pi; } 838 839 private: 840 friend class __shared_count<_Lp>; 841 842 _Sp_counted_base<_Lp>* _M_pi; 843 }; 844 845 // Now that __weak_count is defined we can define this constructor: 846 template<_Lock_policy _Lp> 847 inline 848 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r) 849 : _M_pi(__r._M_pi) 850 { 851 if (_M_pi != nullptr) 852 _M_pi->_M_add_ref_lock(); 853 else 854 __throw_bad_weak_ptr(); 855 } 856 857 // Now that __weak_count is defined we can define this constructor: 858 template<_Lock_policy _Lp> 859 inline 860 __shared_count<_Lp>:: 861 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t) 862 : _M_pi(__r._M_pi) 863 { 864 if (_M_pi != nullptr) 865 if (!_M_pi->_M_add_ref_lock_nothrow()) 866 _M_pi = nullptr; 867 } 868 869 #define __cpp_lib_shared_ptr_arrays 201603 870 871 // Helper traits for shared_ptr of array: 872 873 // A pointer type Y* is said to be compatible with a pointer type T* when 874 // either Y* is convertible to T* or Y is U[N] and T is U cv []. 875 template<typename _Yp_ptr, typename _Tp_ptr> 876 struct __sp_compatible_with 877 : false_type 878 { }; 879 880 template<typename _Yp, typename _Tp> 881 struct __sp_compatible_with<_Yp*, _Tp*> 882 : is_convertible<_Yp*, _Tp*>::type 883 { }; 884 885 template<typename _Up, size_t _Nm> 886 struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]> 887 : true_type 888 { }; 889 890 template<typename _Up, size_t _Nm> 891 struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]> 892 : true_type 893 { }; 894 895 template<typename _Up, size_t _Nm> 896 struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]> 897 : true_type 898 { }; 899 900 template<typename _Up, size_t _Nm> 901 struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]> 902 : true_type 903 { }; 904 905 // Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N]. 906 template<typename _Up, size_t _Nm, typename _Yp, typename = void> 907 struct __sp_is_constructible_arrN 908 : false_type 909 { }; 910 911 template<typename _Up, size_t _Nm, typename _Yp> 912 struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>> 913 : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type 914 { }; 915 916 // Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[]. 917 template<typename _Up, typename _Yp, typename = void> 918 struct __sp_is_constructible_arr 919 : false_type 920 { }; 921 922 template<typename _Up, typename _Yp> 923 struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>> 924 : is_convertible<_Yp(*)[], _Up(*)[]>::type 925 { }; 926 927 // Trait to check if shared_ptr<T> can be constructed from Y*. 928 template<typename _Tp, typename _Yp> 929 struct __sp_is_constructible; 930 931 // When T is U[N], Y(*)[N] shall be convertible to T*; 932 template<typename _Up, size_t _Nm, typename _Yp> 933 struct __sp_is_constructible<_Up[_Nm], _Yp> 934 : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type 935 { }; 936 937 // when T is U[], Y(*)[] shall be convertible to T*; 938 template<typename _Up, typename _Yp> 939 struct __sp_is_constructible<_Up[], _Yp> 940 : __sp_is_constructible_arr<_Up, _Yp>::type 941 { }; 942 943 // otherwise, Y* shall be convertible to T*. 944 template<typename _Tp, typename _Yp> 945 struct __sp_is_constructible 946 : is_convertible<_Yp*, _Tp*>::type 947 { }; 948 949 950 // Define operator* and operator-> for shared_ptr<T>. 951 template<typename _Tp, _Lock_policy _Lp, 952 bool = is_array<_Tp>::value, bool = is_void<_Tp>::value> 953 class __shared_ptr_access 954 { 955 public: 956 using element_type = _Tp; 957 958 element_type& 959 operator*() const noexcept 960 { 961 __glibcxx_assert(_M_get() != nullptr); 962 return *_M_get(); 963 } 964 965 element_type* 966 operator->() const noexcept 967 { 968 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); 969 return _M_get(); 970 } 971 972 private: 973 element_type* 974 _M_get() const noexcept 975 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } 976 }; 977 978 // Define operator-> for shared_ptr<cv void>. 979 template<typename _Tp, _Lock_policy _Lp> 980 class __shared_ptr_access<_Tp, _Lp, false, true> 981 { 982 public: 983 using element_type = _Tp; 984 985 element_type* 986 operator->() const noexcept 987 { 988 auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); 989 _GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr); 990 return __ptr; 991 } 992 }; 993 994 // Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>. 995 template<typename _Tp, _Lock_policy _Lp> 996 class __shared_ptr_access<_Tp, _Lp, true, false> 997 { 998 public: 999 using element_type = typename remove_extent<_Tp>::type; 1000 1001 #if __cplusplus <= 201402L 1002 [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]] 1003 element_type& 1004 operator*() const noexcept 1005 { 1006 __glibcxx_assert(_M_get() != nullptr); 1007 return *_M_get(); 1008 } 1009 1010 [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]] 1011 element_type* 1012 operator->() const noexcept 1013 { 1014 _GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr); 1015 return _M_get(); 1016 } 1017 #endif 1018 1019 element_type& 1020 operator[](ptrdiff_t __i) const 1021 { 1022 __glibcxx_assert(_M_get() != nullptr); 1023 __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value); 1024 return _M_get()[__i]; 1025 } 1026 1027 private: 1028 element_type* 1029 _M_get() const noexcept 1030 { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); } 1031 }; 1032 1033 template<typename _Tp, _Lock_policy _Lp> 1034 class __shared_ptr 1035 : public __shared_ptr_access<_Tp, _Lp> 1036 { 1037 public: 1038 using element_type = typename remove_extent<_Tp>::type; 1039 1040 private: 1041 // Constraint for taking ownership of a pointer of type _Yp*: 1042 template<typename _Yp> 1043 using _SafeConv 1044 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type; 1045 1046 // Constraint for construction from shared_ptr and weak_ptr: 1047 template<typename _Yp, typename _Res = void> 1048 using _Compatible = typename 1049 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; 1050 1051 // Constraint for assignment from shared_ptr and weak_ptr: 1052 template<typename _Yp> 1053 using _Assignable = _Compatible<_Yp, __shared_ptr&>; 1054 1055 // Constraint for construction from unique_ptr: 1056 template<typename _Yp, typename _Del, typename _Res = void, 1057 typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer> 1058 using _UniqCompatible = typename enable_if<__and_< 1059 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*> 1060 >::value, _Res>::type; 1061 1062 // Constraint for assignment from unique_ptr: 1063 template<typename _Yp, typename _Del> 1064 using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>; 1065 1066 public: 1067 1068 #if __cplusplus > 201402L 1069 using weak_type = __weak_ptr<_Tp, _Lp>; 1070 #endif 1071 1072 constexpr __shared_ptr() noexcept 1073 : _M_ptr(0), _M_refcount() 1074 { } 1075 1076 template<typename _Yp, typename = _SafeConv<_Yp>> 1077 explicit 1078 __shared_ptr(_Yp* __p) 1079 : _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type()) 1080 { 1081 static_assert( !is_void<_Yp>::value, "incomplete type" ); 1082 static_assert( sizeof(_Yp) > 0, "incomplete type" ); 1083 _M_enable_shared_from_this_with(__p); 1084 } 1085 1086 template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>> 1087 __shared_ptr(_Yp* __p, _Deleter __d) 1088 : _M_ptr(__p), _M_refcount(__p, std::move(__d)) 1089 { 1090 static_assert(__is_invocable<_Deleter&, _Yp*&>::value, 1091 "deleter expression d(p) is well-formed"); 1092 _M_enable_shared_from_this_with(__p); 1093 } 1094 1095 template<typename _Yp, typename _Deleter, typename _Alloc, 1096 typename = _SafeConv<_Yp>> 1097 __shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) 1098 : _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a)) 1099 { 1100 static_assert(__is_invocable<_Deleter&, _Yp*&>::value, 1101 "deleter expression d(p) is well-formed"); 1102 _M_enable_shared_from_this_with(__p); 1103 } 1104 1105 template<typename _Deleter> 1106 __shared_ptr(nullptr_t __p, _Deleter __d) 1107 : _M_ptr(0), _M_refcount(__p, std::move(__d)) 1108 { } 1109 1110 template<typename _Deleter, typename _Alloc> 1111 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 1112 : _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a)) 1113 { } 1114 1115 template<typename _Yp> 1116 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r, 1117 element_type* __p) noexcept 1118 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 1119 { } 1120 1121 __shared_ptr(const __shared_ptr&) noexcept = default; 1122 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 1123 ~__shared_ptr() = default; 1124 1125 template<typename _Yp, typename = _Compatible<_Yp>> 1126 __shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1127 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1128 { } 1129 1130 __shared_ptr(__shared_ptr&& __r) noexcept 1131 : _M_ptr(__r._M_ptr), _M_refcount() 1132 { 1133 _M_refcount._M_swap(__r._M_refcount); 1134 __r._M_ptr = 0; 1135 } 1136 1137 template<typename _Yp, typename = _Compatible<_Yp>> 1138 __shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept 1139 : _M_ptr(__r._M_ptr), _M_refcount() 1140 { 1141 _M_refcount._M_swap(__r._M_refcount); 1142 __r._M_ptr = 0; 1143 } 1144 1145 template<typename _Yp, typename = _Compatible<_Yp>> 1146 explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r) 1147 : _M_refcount(__r._M_refcount) // may throw 1148 { 1149 // It is now safe to copy __r._M_ptr, as 1150 // _M_refcount(__r._M_refcount) did not throw. 1151 _M_ptr = __r._M_ptr; 1152 } 1153 1154 // If an exception is thrown this constructor has no effect. 1155 template<typename _Yp, typename _Del, 1156 typename = _UniqCompatible<_Yp, _Del>> 1157 __shared_ptr(unique_ptr<_Yp, _Del>&& __r) 1158 : _M_ptr(__r.get()), _M_refcount() 1159 { 1160 auto __raw = _S_raw_ptr(__r.get()); 1161 _M_refcount = __shared_count<_Lp>(std::move(__r)); 1162 _M_enable_shared_from_this_with(__raw); 1163 } 1164 1165 #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED 1166 protected: 1167 // If an exception is thrown this constructor has no effect. 1168 template<typename _Tp1, typename _Del, 1169 typename enable_if<__and_< 1170 __not_<is_array<_Tp>>, is_array<_Tp1>, 1171 is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*> 1172 >::value, bool>::type = true> 1173 __shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete) 1174 : _M_ptr(__r.get()), _M_refcount() 1175 { 1176 auto __raw = _S_raw_ptr(__r.get()); 1177 _M_refcount = __shared_count<_Lp>(std::move(__r)); 1178 _M_enable_shared_from_this_with(__raw); 1179 } 1180 public: 1181 #endif 1182 1183 #if _GLIBCXX_USE_DEPRECATED 1184 // Postcondition: use_count() == 1 and __r.get() == 0 1185 template<typename _Yp, typename = _Compatible<_Yp>> 1186 __shared_ptr(auto_ptr<_Yp>&& __r); 1187 #endif 1188 1189 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { } 1190 1191 template<typename _Yp> 1192 _Assignable<_Yp> 1193 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1194 { 1195 _M_ptr = __r._M_ptr; 1196 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 1197 return *this; 1198 } 1199 1200 #if _GLIBCXX_USE_DEPRECATED 1201 template<typename _Yp> 1202 _Assignable<_Yp> 1203 operator=(auto_ptr<_Yp>&& __r) 1204 { 1205 __shared_ptr(std::move(__r)).swap(*this); 1206 return *this; 1207 } 1208 #endif 1209 1210 __shared_ptr& 1211 operator=(__shared_ptr&& __r) noexcept 1212 { 1213 __shared_ptr(std::move(__r)).swap(*this); 1214 return *this; 1215 } 1216 1217 template<class _Yp> 1218 _Assignable<_Yp> 1219 operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept 1220 { 1221 __shared_ptr(std::move(__r)).swap(*this); 1222 return *this; 1223 } 1224 1225 template<typename _Yp, typename _Del> 1226 _UniqAssignable<_Yp, _Del> 1227 operator=(unique_ptr<_Yp, _Del>&& __r) 1228 { 1229 __shared_ptr(std::move(__r)).swap(*this); 1230 return *this; 1231 } 1232 1233 void 1234 reset() noexcept 1235 { __shared_ptr().swap(*this); } 1236 1237 template<typename _Yp> 1238 _SafeConv<_Yp> 1239 reset(_Yp* __p) // _Yp must be complete. 1240 { 1241 // Catch self-reset errors. 1242 __glibcxx_assert(__p == 0 || __p != _M_ptr); 1243 __shared_ptr(__p).swap(*this); 1244 } 1245 1246 template<typename _Yp, typename _Deleter> 1247 _SafeConv<_Yp> 1248 reset(_Yp* __p, _Deleter __d) 1249 { __shared_ptr(__p, std::move(__d)).swap(*this); } 1250 1251 template<typename _Yp, typename _Deleter, typename _Alloc> 1252 _SafeConv<_Yp> 1253 reset(_Yp* __p, _Deleter __d, _Alloc __a) 1254 { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); } 1255 1256 element_type* 1257 get() const noexcept 1258 { return _M_ptr; } 1259 1260 explicit operator bool() const // never throws 1261 { return _M_ptr == 0 ? false : true; } 1262 1263 bool 1264 unique() const noexcept 1265 { return _M_refcount._M_unique(); } 1266 1267 long 1268 use_count() const noexcept 1269 { return _M_refcount._M_get_use_count(); } 1270 1271 void 1272 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 1273 { 1274 std::swap(_M_ptr, __other._M_ptr); 1275 _M_refcount._M_swap(__other._M_refcount); 1276 } 1277 1278 template<typename _Tp1> 1279 bool 1280 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1281 { return _M_refcount._M_less(__rhs._M_refcount); } 1282 1283 template<typename _Tp1> 1284 bool 1285 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1286 { return _M_refcount._M_less(__rhs._M_refcount); } 1287 1288 #if __cpp_rtti 1289 protected: 1290 // This constructor is non-standard, it is used by allocate_shared. 1291 template<typename _Alloc, typename... _Args> 1292 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1293 _Args&&... __args) 1294 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 1295 std::forward<_Args>(__args)...) 1296 { 1297 // _M_ptr needs to point to the newly constructed object. 1298 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 1299 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 1300 _M_ptr = static_cast<_Tp*>(__p); 1301 _M_enable_shared_from_this_with(_M_ptr); 1302 } 1303 #else 1304 template<typename _Alloc> 1305 struct _Deleter 1306 { 1307 void operator()(typename _Alloc::value_type* __ptr) 1308 { 1309 __allocated_ptr<_Alloc> __guard{ _M_alloc, __ptr }; 1310 allocator_traits<_Alloc>::destroy(_M_alloc, __guard.get()); 1311 } 1312 _Alloc _M_alloc; 1313 }; 1314 1315 template<typename _Alloc, typename... _Args> 1316 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1317 _Args&&... __args) 1318 : _M_ptr(), _M_refcount() 1319 { 1320 typedef typename allocator_traits<_Alloc>::template 1321 rebind_traits<typename std::remove_cv<_Tp>::type> __traits; 1322 _Deleter<typename __traits::allocator_type> __del = { __a }; 1323 auto __guard = std::__allocate_guarded(__del._M_alloc); 1324 auto __ptr = __guard.get(); 1325 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1326 // 2070. allocate_shared should use allocator_traits<A>::construct 1327 __traits::construct(__del._M_alloc, __ptr, 1328 std::forward<_Args>(__args)...); 1329 __guard = nullptr; 1330 __shared_count<_Lp> __count(__ptr, __del, __del._M_alloc); 1331 _M_refcount._M_swap(__count); 1332 _M_ptr = __ptr; 1333 _M_enable_shared_from_this_with(_M_ptr); 1334 } 1335 #endif 1336 1337 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1338 typename... _Args> 1339 friend __shared_ptr<_Tp1, _Lp1> 1340 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1341 1342 // This constructor is used by __weak_ptr::lock() and 1343 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t). 1344 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t) 1345 : _M_refcount(__r._M_refcount, std::nothrow) 1346 { 1347 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr; 1348 } 1349 1350 friend class __weak_ptr<_Tp, _Lp>; 1351 1352 private: 1353 1354 template<typename _Yp> 1355 using __esft_base_t = decltype(__enable_shared_from_this_base( 1356 std::declval<const __shared_count<_Lp>&>(), 1357 std::declval<_Yp*>())); 1358 1359 // Detect an accessible and unambiguous enable_shared_from_this base. 1360 template<typename _Yp, typename = void> 1361 struct __has_esft_base 1362 : false_type { }; 1363 1364 template<typename _Yp> 1365 struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>> 1366 : __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays 1367 1368 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> 1369 typename enable_if<__has_esft_base<_Yp2>::value>::type 1370 _M_enable_shared_from_this_with(_Yp* __p) noexcept 1371 { 1372 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p)) 1373 __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount); 1374 } 1375 1376 template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type> 1377 typename enable_if<!__has_esft_base<_Yp2>::value>::type 1378 _M_enable_shared_from_this_with(_Yp*) noexcept 1379 { } 1380 1381 void* 1382 _M_get_deleter(const std::type_info& __ti) const noexcept 1383 { return _M_refcount._M_get_deleter(__ti); } 1384 1385 template<typename _Tp1> 1386 static _Tp1* 1387 _S_raw_ptr(_Tp1* __ptr) 1388 { return __ptr; } 1389 1390 template<typename _Tp1> 1391 static auto 1392 _S_raw_ptr(_Tp1 __ptr) -> decltype(std::__addressof(*__ptr)) 1393 { return std::__addressof(*__ptr); } 1394 1395 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1396 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1397 1398 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1399 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 1400 1401 element_type* _M_ptr; // Contained pointer. 1402 __shared_count<_Lp> _M_refcount; // Reference counter. 1403 }; 1404 1405 1406 // 20.7.2.2.7 shared_ptr comparisons 1407 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1408 inline bool 1409 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1410 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1411 { return __a.get() == __b.get(); } 1412 1413 template<typename _Tp, _Lock_policy _Lp> 1414 inline bool 1415 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1416 { return !__a; } 1417 1418 template<typename _Tp, _Lock_policy _Lp> 1419 inline bool 1420 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1421 { return !__a; } 1422 1423 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1424 inline bool 1425 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1426 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1427 { return __a.get() != __b.get(); } 1428 1429 template<typename _Tp, _Lock_policy _Lp> 1430 inline bool 1431 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1432 { return (bool)__a; } 1433 1434 template<typename _Tp, _Lock_policy _Lp> 1435 inline bool 1436 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1437 { return (bool)__a; } 1438 1439 template<typename _Tp, typename _Up, _Lock_policy _Lp> 1440 inline bool 1441 operator<(const __shared_ptr<_Tp, _Lp>& __a, 1442 const __shared_ptr<_Up, _Lp>& __b) noexcept 1443 { 1444 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1445 using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type; 1446 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; 1447 return less<_Vp>()(__a.get(), __b.get()); 1448 } 1449 1450 template<typename _Tp, _Lock_policy _Lp> 1451 inline bool 1452 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1453 { 1454 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1455 return less<_Tp_elt*>()(__a.get(), nullptr); 1456 } 1457 1458 template<typename _Tp, _Lock_policy _Lp> 1459 inline bool 1460 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1461 { 1462 using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type; 1463 return less<_Tp_elt*>()(nullptr, __a.get()); 1464 } 1465 1466 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1467 inline bool 1468 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 1469 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1470 { return !(__b < __a); } 1471 1472 template<typename _Tp, _Lock_policy _Lp> 1473 inline bool 1474 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1475 { return !(nullptr < __a); } 1476 1477 template<typename _Tp, _Lock_policy _Lp> 1478 inline bool 1479 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1480 { return !(__a < nullptr); } 1481 1482 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1483 inline bool 1484 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 1485 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1486 { return (__b < __a); } 1487 1488 template<typename _Tp, _Lock_policy _Lp> 1489 inline bool 1490 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1491 { return nullptr < __a; } 1492 1493 template<typename _Tp, _Lock_policy _Lp> 1494 inline bool 1495 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1496 { return __a < nullptr; } 1497 1498 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1499 inline bool 1500 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 1501 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1502 { return !(__a < __b); } 1503 1504 template<typename _Tp, _Lock_policy _Lp> 1505 inline bool 1506 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1507 { return !(__a < nullptr); } 1508 1509 template<typename _Tp, _Lock_policy _Lp> 1510 inline bool 1511 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1512 { return !(nullptr < __a); } 1513 1514 template<typename _Sp> 1515 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1516 { 1517 bool 1518 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 1519 { 1520 typedef typename _Sp::element_type element_type; 1521 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1522 } 1523 }; 1524 1525 template<typename _Tp, _Lock_policy _Lp> 1526 struct less<__shared_ptr<_Tp, _Lp>> 1527 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1528 { }; 1529 1530 // 20.7.2.2.8 shared_ptr specialized algorithms. 1531 template<typename _Tp, _Lock_policy _Lp> 1532 inline void 1533 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 1534 { __a.swap(__b); } 1535 1536 // 20.7.2.2.9 shared_ptr casts 1537 1538 // The seemingly equivalent code: 1539 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1540 // will eventually result in undefined behaviour, attempting to 1541 // delete the same object twice. 1542 /// static_pointer_cast 1543 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1544 inline __shared_ptr<_Tp, _Lp> 1545 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1546 { 1547 using _Sp = __shared_ptr<_Tp, _Lp>; 1548 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); 1549 } 1550 1551 // The seemingly equivalent code: 1552 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1553 // will eventually result in undefined behaviour, attempting to 1554 // delete the same object twice. 1555 /// const_pointer_cast 1556 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1557 inline __shared_ptr<_Tp, _Lp> 1558 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1559 { 1560 using _Sp = __shared_ptr<_Tp, _Lp>; 1561 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); 1562 } 1563 1564 // The seemingly equivalent code: 1565 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1566 // will eventually result in undefined behaviour, attempting to 1567 // delete the same object twice. 1568 /// dynamic_pointer_cast 1569 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1570 inline __shared_ptr<_Tp, _Lp> 1571 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1572 { 1573 using _Sp = __shared_ptr<_Tp, _Lp>; 1574 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) 1575 return _Sp(__r, __p); 1576 return _Sp(); 1577 } 1578 1579 #if __cplusplus > 201402L 1580 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1581 inline __shared_ptr<_Tp, _Lp> 1582 reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1583 { 1584 using _Sp = __shared_ptr<_Tp, _Lp>; 1585 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); 1586 } 1587 #endif 1588 1589 template<typename _Tp, _Lock_policy _Lp> 1590 class __weak_ptr 1591 { 1592 template<typename _Yp, typename _Res = void> 1593 using _Compatible = typename 1594 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type; 1595 1596 // Constraint for assignment from shared_ptr and weak_ptr: 1597 template<typename _Yp> 1598 using _Assignable = _Compatible<_Yp, __weak_ptr&>; 1599 1600 public: 1601 using element_type = typename remove_extent<_Tp>::type; 1602 1603 constexpr __weak_ptr() noexcept 1604 : _M_ptr(nullptr), _M_refcount() 1605 { } 1606 1607 __weak_ptr(const __weak_ptr&) noexcept = default; 1608 1609 ~__weak_ptr() = default; 1610 1611 // The "obvious" converting constructor implementation: 1612 // 1613 // template<typename _Tp1> 1614 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1615 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1616 // { } 1617 // 1618 // has a serious problem. 1619 // 1620 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1621 // conversion may require access to *__r._M_ptr (virtual inheritance). 1622 // 1623 // It is not possible to avoid spurious access violations since 1624 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1625 template<typename _Yp, typename = _Compatible<_Yp>> 1626 __weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept 1627 : _M_refcount(__r._M_refcount) 1628 { _M_ptr = __r.lock().get(); } 1629 1630 template<typename _Yp, typename = _Compatible<_Yp>> 1631 __weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1632 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1633 { } 1634 1635 __weak_ptr(__weak_ptr&& __r) noexcept 1636 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount)) 1637 { __r._M_ptr = nullptr; } 1638 1639 template<typename _Yp, typename = _Compatible<_Yp>> 1640 __weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept 1641 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount)) 1642 { __r._M_ptr = nullptr; } 1643 1644 __weak_ptr& 1645 operator=(const __weak_ptr& __r) noexcept = default; 1646 1647 template<typename _Yp> 1648 _Assignable<_Yp> 1649 operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept 1650 { 1651 _M_ptr = __r.lock().get(); 1652 _M_refcount = __r._M_refcount; 1653 return *this; 1654 } 1655 1656 template<typename _Yp> 1657 _Assignable<_Yp> 1658 operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept 1659 { 1660 _M_ptr = __r._M_ptr; 1661 _M_refcount = __r._M_refcount; 1662 return *this; 1663 } 1664 1665 __weak_ptr& 1666 operator=(__weak_ptr&& __r) noexcept 1667 { 1668 _M_ptr = __r._M_ptr; 1669 _M_refcount = std::move(__r._M_refcount); 1670 __r._M_ptr = nullptr; 1671 return *this; 1672 } 1673 1674 template<typename _Yp> 1675 _Assignable<_Yp> 1676 operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept 1677 { 1678 _M_ptr = __r.lock().get(); 1679 _M_refcount = std::move(__r._M_refcount); 1680 __r._M_ptr = nullptr; 1681 return *this; 1682 } 1683 1684 __shared_ptr<_Tp, _Lp> 1685 lock() const noexcept 1686 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); } 1687 1688 long 1689 use_count() const noexcept 1690 { return _M_refcount._M_get_use_count(); } 1691 1692 bool 1693 expired() const noexcept 1694 { return _M_refcount._M_get_use_count() == 0; } 1695 1696 template<typename _Tp1> 1697 bool 1698 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept 1699 { return _M_refcount._M_less(__rhs._M_refcount); } 1700 1701 template<typename _Tp1> 1702 bool 1703 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept 1704 { return _M_refcount._M_less(__rhs._M_refcount); } 1705 1706 void 1707 reset() noexcept 1708 { __weak_ptr().swap(*this); } 1709 1710 void 1711 swap(__weak_ptr& __s) noexcept 1712 { 1713 std::swap(_M_ptr, __s._M_ptr); 1714 _M_refcount._M_swap(__s._M_refcount); 1715 } 1716 1717 private: 1718 // Used by __enable_shared_from_this. 1719 void 1720 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 1721 { 1722 if (use_count() == 0) 1723 { 1724 _M_ptr = __ptr; 1725 _M_refcount = __refcount; 1726 } 1727 } 1728 1729 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1730 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1731 friend class __enable_shared_from_this<_Tp, _Lp>; 1732 friend class enable_shared_from_this<_Tp>; 1733 1734 element_type* _M_ptr; // Contained pointer. 1735 __weak_count<_Lp> _M_refcount; // Reference counter. 1736 }; 1737 1738 // 20.7.2.3.6 weak_ptr specialized algorithms. 1739 template<typename _Tp, _Lock_policy _Lp> 1740 inline void 1741 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 1742 { __a.swap(__b); } 1743 1744 template<typename _Tp, typename _Tp1> 1745 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1746 { 1747 bool 1748 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept 1749 { return __lhs.owner_before(__rhs); } 1750 1751 bool 1752 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept 1753 { return __lhs.owner_before(__rhs); } 1754 1755 bool 1756 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept 1757 { return __lhs.owner_before(__rhs); } 1758 }; 1759 1760 template<> 1761 struct _Sp_owner_less<void, void> 1762 { 1763 template<typename _Tp, typename _Up> 1764 auto 1765 operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept 1766 -> decltype(__lhs.owner_before(__rhs)) 1767 { return __lhs.owner_before(__rhs); } 1768 1769 using is_transparent = void; 1770 }; 1771 1772 template<typename _Tp, _Lock_policy _Lp> 1773 struct owner_less<__shared_ptr<_Tp, _Lp>> 1774 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1775 { }; 1776 1777 template<typename _Tp, _Lock_policy _Lp> 1778 struct owner_less<__weak_ptr<_Tp, _Lp>> 1779 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1780 { }; 1781 1782 1783 template<typename _Tp, _Lock_policy _Lp> 1784 class __enable_shared_from_this 1785 { 1786 protected: 1787 constexpr __enable_shared_from_this() noexcept { } 1788 1789 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 1790 1791 __enable_shared_from_this& 1792 operator=(const __enable_shared_from_this&) noexcept 1793 { return *this; } 1794 1795 ~__enable_shared_from_this() { } 1796 1797 public: 1798 __shared_ptr<_Tp, _Lp> 1799 shared_from_this() 1800 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1801 1802 __shared_ptr<const _Tp, _Lp> 1803 shared_from_this() const 1804 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1805 1806 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 1807 __weak_ptr<_Tp, _Lp> 1808 weak_from_this() noexcept 1809 { return this->_M_weak_this; } 1810 1811 __weak_ptr<const _Tp, _Lp> 1812 weak_from_this() const noexcept 1813 { return this->_M_weak_this; } 1814 #endif 1815 1816 private: 1817 template<typename _Tp1> 1818 void 1819 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 1820 { _M_weak_this._M_assign(__p, __n); } 1821 1822 friend const __enable_shared_from_this* 1823 __enable_shared_from_this_base(const __shared_count<_Lp>&, 1824 const __enable_shared_from_this* __p) 1825 { return __p; } 1826 1827 template<typename, _Lock_policy> 1828 friend class __shared_ptr; 1829 1830 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1831 }; 1832 1833 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1834 inline __shared_ptr<_Tp, _Lp> 1835 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1836 { 1837 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1838 std::forward<_Args>(__args)...); 1839 } 1840 1841 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1842 inline __shared_ptr<_Tp, _Lp> 1843 __make_shared(_Args&&... __args) 1844 { 1845 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1846 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1847 std::forward<_Args>(__args)...); 1848 } 1849 1850 /// std::hash specialization for __shared_ptr. 1851 template<typename _Tp, _Lock_policy _Lp> 1852 struct hash<__shared_ptr<_Tp, _Lp>> 1853 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 1854 { 1855 size_t 1856 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1857 { 1858 return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()( 1859 __s.get()); 1860 } 1861 }; 1862 1863 _GLIBCXX_END_NAMESPACE_VERSION 1864 } // namespace 1865 1866 #endif // _SHARED_PTR_BASE_H 1867