1 // shared_ptr and weak_ptr implementation details -*- C++ -*- 2 3 // Copyright (C) 2007-2013 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 namespace std _GLIBCXX_VISIBILITY(default) 53 { 54 _GLIBCXX_BEGIN_NAMESPACE_VERSION 55 56 #if _GLIBCXX_USE_DEPRECATED 57 template<typename> class auto_ptr; 58 #endif 59 60 /** 61 * @brief Exception possibly thrown by @c shared_ptr. 62 * @ingroup exceptions 63 */ 64 class bad_weak_ptr : public std::exception 65 { 66 public: 67 virtual char const* 68 what() const noexcept; 69 70 virtual ~bad_weak_ptr() noexcept; 71 }; 72 73 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 74 inline void 75 __throw_bad_weak_ptr() 76 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } 77 78 using __gnu_cxx::_Lock_policy; 79 using __gnu_cxx::__default_lock_policy; 80 using __gnu_cxx::_S_single; 81 using __gnu_cxx::_S_mutex; 82 using __gnu_cxx::_S_atomic; 83 84 // Empty helper class except when the template argument is _S_mutex. 85 template<_Lock_policy _Lp> 86 class _Mutex_base 87 { 88 protected: 89 // The atomic policy uses fully-fenced builtins, single doesn't care. 90 enum { _S_need_barriers = 0 }; 91 }; 92 93 template<> 94 class _Mutex_base<_S_mutex> 95 : public __gnu_cxx::__mutex 96 { 97 protected: 98 // This policy is used when atomic builtins are not available. 99 // The replacement atomic operations might not have the necessary 100 // memory barriers. 101 enum { _S_need_barriers = 1 }; 102 }; 103 104 template<_Lock_policy _Lp = __default_lock_policy> 105 class _Sp_counted_base 106 : public _Mutex_base<_Lp> 107 { 108 public: 109 _Sp_counted_base() noexcept 110 : _M_use_count(1), _M_weak_count(1) { } 111 112 virtual 113 ~_Sp_counted_base() noexcept 114 { } 115 116 // Called when _M_use_count drops to zero, to release the resources 117 // managed by *this. 118 virtual void 119 _M_dispose() noexcept = 0; 120 121 // Called when _M_weak_count drops to zero. 122 virtual void 123 _M_destroy() noexcept 124 { delete this; } 125 126 virtual void* 127 _M_get_deleter(const std::type_info&) = 0; 128 129 void 130 _M_add_ref_copy() 131 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 132 133 void 134 _M_add_ref_lock(); 135 136 void 137 _M_release() noexcept 138 { 139 // Be race-detector-friendly. For more info see bits/c++config. 140 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 141 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 142 { 143 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 144 _M_dispose(); 145 // There must be a memory barrier between dispose() and destroy() 146 // to ensure that the effects of dispose() are observed in the 147 // thread that runs destroy(). 148 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 149 if (_Mutex_base<_Lp>::_S_need_barriers) 150 { 151 _GLIBCXX_READ_MEM_BARRIER; 152 _GLIBCXX_WRITE_MEM_BARRIER; 153 } 154 155 // Be race-detector-friendly. For more info see bits/c++config. 156 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 157 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 158 -1) == 1) 159 { 160 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 161 _M_destroy(); 162 } 163 } 164 } 165 166 void 167 _M_weak_add_ref() noexcept 168 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 169 170 void 171 _M_weak_release() noexcept 172 { 173 // Be race-detector-friendly. For more info see bits/c++config. 174 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 175 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 176 { 177 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 178 if (_Mutex_base<_Lp>::_S_need_barriers) 179 { 180 // See _M_release(), 181 // destroy() must observe results of dispose() 182 _GLIBCXX_READ_MEM_BARRIER; 183 _GLIBCXX_WRITE_MEM_BARRIER; 184 } 185 _M_destroy(); 186 } 187 } 188 189 long 190 _M_get_use_count() const noexcept 191 { 192 // No memory barrier is used here so there is no synchronization 193 // with other threads. 194 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); 195 } 196 197 private: 198 _Sp_counted_base(_Sp_counted_base const&) = delete; 199 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; 200 201 _Atomic_word _M_use_count; // #shared 202 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 203 }; 204 205 template<> 206 inline void 207 _Sp_counted_base<_S_single>:: 208 _M_add_ref_lock() 209 { 210 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 211 { 212 _M_use_count = 0; 213 __throw_bad_weak_ptr(); 214 } 215 } 216 217 template<> 218 inline void 219 _Sp_counted_base<_S_mutex>:: 220 _M_add_ref_lock() 221 { 222 __gnu_cxx::__scoped_lock sentry(*this); 223 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 224 { 225 _M_use_count = 0; 226 __throw_bad_weak_ptr(); 227 } 228 } 229 230 template<> 231 inline void 232 _Sp_counted_base<_S_atomic>:: 233 _M_add_ref_lock() 234 { 235 // Perform lock-free add-if-not-zero operation. 236 _Atomic_word __count = _M_get_use_count(); 237 do 238 { 239 if (__count == 0) 240 __throw_bad_weak_ptr(); 241 // Replace the current counter value with the old value + 1, as 242 // long as it's not changed meanwhile. 243 } 244 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 245 true, __ATOMIC_ACQ_REL, 246 __ATOMIC_RELAXED)); 247 } 248 249 250 // Forward declarations. 251 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 252 class __shared_ptr; 253 254 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 255 class __weak_ptr; 256 257 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 258 class __enable_shared_from_this; 259 260 template<typename _Tp> 261 class shared_ptr; 262 263 template<typename _Tp> 264 class weak_ptr; 265 266 template<typename _Tp> 267 struct owner_less; 268 269 template<typename _Tp> 270 class enable_shared_from_this; 271 272 template<_Lock_policy _Lp = __default_lock_policy> 273 class __weak_count; 274 275 template<_Lock_policy _Lp = __default_lock_policy> 276 class __shared_count; 277 278 279 // Counted ptr with no deleter or allocator support 280 template<typename _Ptr, _Lock_policy _Lp> 281 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> 282 { 283 public: 284 explicit 285 _Sp_counted_ptr(_Ptr __p) 286 : _M_ptr(__p) { } 287 288 virtual void 289 _M_dispose() noexcept 290 { delete _M_ptr; } 291 292 virtual void 293 _M_destroy() noexcept 294 { delete this; } 295 296 virtual void* 297 _M_get_deleter(const std::type_info&) 298 { return 0; } 299 300 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 301 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 302 303 protected: 304 _Ptr _M_ptr; // copy constructor must not throw 305 }; 306 307 template<> 308 inline void 309 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } 310 311 template<> 312 inline void 313 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } 314 315 template<> 316 inline void 317 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } 318 319 // Support for custom deleter and/or allocator 320 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 321 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> 322 { 323 // Helper class that stores the Deleter and also acts as an allocator. 324 // Used to dispose of the owned pointer and the internal refcount 325 // Requires that copies of _Alloc can free each other's memory. 326 struct _My_Deleter 327 : public _Alloc // copy constructor must not throw 328 { 329 _Deleter _M_del; // copy constructor must not throw 330 _My_Deleter(_Deleter __d, const _Alloc& __a) 331 : _Alloc(__a), _M_del(__d) { } 332 }; 333 334 public: 335 // __d(__p) must not throw. 336 _Sp_counted_deleter(_Ptr __p, _Deleter __d) 337 : _M_ptr(__p), _M_del(__d, _Alloc()) { } 338 339 // __d(__p) must not throw. 340 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) 341 : _M_ptr(__p), _M_del(__d, __a) { } 342 343 ~_Sp_counted_deleter() noexcept { } 344 345 virtual void 346 _M_dispose() noexcept 347 { _M_del._M_del(_M_ptr); } 348 349 virtual void 350 _M_destroy() noexcept 351 { 352 typedef typename allocator_traits<_Alloc>::template 353 rebind_traits<_Sp_counted_deleter> _Alloc_traits; 354 typename _Alloc_traits::allocator_type __a(_M_del); 355 _Alloc_traits::destroy(__a, this); 356 _Alloc_traits::deallocate(__a, this, 1); 357 } 358 359 virtual void* 360 _M_get_deleter(const std::type_info& __ti) 361 { 362 #ifdef __GXX_RTTI 363 return __ti == typeid(_Deleter) ? &_M_del._M_del : 0; 364 #else 365 return 0; 366 #endif 367 } 368 369 protected: 370 _Ptr _M_ptr; // copy constructor must not throw 371 _My_Deleter _M_del; // copy constructor must not throw 372 }; 373 374 // helpers for make_shared / allocate_shared 375 376 struct _Sp_make_shared_tag { }; 377 378 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 379 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> 380 { 381 // Helper class that stores the pointer and also acts as an allocator. 382 // Used to dispose of the owned pointer and the internal refcount 383 // Requires that copies of _Alloc can free each other's memory. 384 struct _Impl 385 : public _Alloc // copy constructor must not throw 386 { 387 _Impl(_Alloc __a) : _Alloc(__a), _M_ptr() { } 388 _Tp* _M_ptr; 389 }; 390 391 public: 392 template<typename... _Args> 393 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 394 : _M_impl(__a) 395 { 396 _M_impl._M_ptr = static_cast<_Tp*>(static_cast<void*>(&_M_storage)); 397 // _GLIBCXX_RESOLVE_LIB_DEFECTS 398 // 2070. allocate_shared should use allocator_traits<A>::construct 399 allocator_traits<_Alloc>::construct(__a, _M_impl._M_ptr, 400 std::forward<_Args>(__args)...); // might throw 401 } 402 403 ~_Sp_counted_ptr_inplace() noexcept { } 404 405 virtual void 406 _M_dispose() noexcept 407 { allocator_traits<_Alloc>::destroy(_M_impl, _M_impl._M_ptr); } 408 409 // Override because the allocator needs to know the dynamic type 410 virtual void 411 _M_destroy() noexcept 412 { 413 typedef typename allocator_traits<_Alloc>::template 414 rebind_traits<_Sp_counted_ptr_inplace> _Alloc_traits; 415 typename _Alloc_traits::allocator_type __a(_M_impl); 416 _Alloc_traits::destroy(__a, this); 417 _Alloc_traits::deallocate(__a, this, 1); 418 } 419 420 // Sneaky trick so __shared_ptr can get the managed pointer 421 virtual void* 422 _M_get_deleter(const std::type_info& __ti) noexcept 423 { 424 #ifdef __GXX_RTTI 425 return __ti == typeid(_Sp_make_shared_tag) 426 ? static_cast<void*>(&_M_storage) 427 : 0; 428 #else 429 return 0; 430 #endif 431 } 432 433 private: 434 _Impl _M_impl; 435 typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type 436 _M_storage; 437 }; 438 439 template<_Lock_policy _Lp> 440 class __shared_count 441 { 442 public: 443 constexpr __shared_count() noexcept : _M_pi(0) 444 { } 445 446 template<typename _Ptr> 447 explicit 448 __shared_count(_Ptr __p) : _M_pi(0) 449 { 450 __try 451 { 452 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 453 } 454 __catch(...) 455 { 456 delete __p; 457 __throw_exception_again; 458 } 459 } 460 461 template<typename _Ptr, typename _Deleter> 462 __shared_count(_Ptr __p, _Deleter __d) 463 : __shared_count(__p, std::move(__d), allocator<int>()) 464 { } 465 466 template<typename _Ptr, typename _Deleter, typename _Alloc> 467 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 468 { 469 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 470 typedef typename allocator_traits<_Alloc>::template 471 rebind_traits<_Sp_cd_type> _Alloc_traits; 472 typename _Alloc_traits::allocator_type __a2(__a); 473 _Sp_cd_type* __mem = 0; 474 __try 475 { 476 __mem = _Alloc_traits::allocate(__a2, 1); 477 _Alloc_traits::construct(__a2, __mem, 478 __p, std::move(__d), std::move(__a)); 479 _M_pi = __mem; 480 } 481 __catch(...) 482 { 483 __d(__p); // Call _Deleter on __p. 484 if (__mem) 485 _Alloc_traits::deallocate(__a2, __mem, 1); 486 __throw_exception_again; 487 } 488 } 489 490 template<typename _Tp, typename _Alloc, typename... _Args> 491 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 492 _Args&&... __args) 493 : _M_pi(0) 494 { 495 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 496 typedef typename allocator_traits<_Alloc>::template 497 rebind_traits<_Sp_cp_type> _Alloc_traits; 498 typename _Alloc_traits::allocator_type __a2(__a); 499 _Sp_cp_type* __mem = _Alloc_traits::allocate(__a2, 1); 500 __try 501 { 502 _Alloc_traits::construct(__a2, __mem, std::move(__a), 503 std::forward<_Args>(__args)...); 504 _M_pi = __mem; 505 } 506 __catch(...) 507 { 508 _Alloc_traits::deallocate(__a2, __mem, 1); 509 __throw_exception_again; 510 } 511 } 512 513 #if _GLIBCXX_USE_DEPRECATED 514 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 515 template<typename _Tp> 516 explicit 517 __shared_count(std::auto_ptr<_Tp>&& __r); 518 #endif 519 520 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 521 template<typename _Tp, typename _Del> 522 explicit 523 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0) 524 { 525 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer; 526 using _Del2 = typename conditional<is_reference<_Del>::value, 527 reference_wrapper<typename remove_reference<_Del>::type>, 528 _Del>::type; 529 using _Sp_cd_type 530 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>; 531 using _Alloc = allocator<_Sp_cd_type>; 532 using _Alloc_traits = allocator_traits<_Alloc>; 533 _Alloc __a; 534 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1); 535 _Alloc_traits::construct(__a, __mem, __r.release(), 536 __r.get_deleter()); // non-throwing 537 _M_pi = __mem; 538 } 539 540 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 541 explicit __shared_count(const __weak_count<_Lp>& __r); 542 543 ~__shared_count() noexcept 544 { 545 if (_M_pi != nullptr) 546 _M_pi->_M_release(); 547 } 548 549 __shared_count(const __shared_count& __r) noexcept 550 : _M_pi(__r._M_pi) 551 { 552 if (_M_pi != 0) 553 _M_pi->_M_add_ref_copy(); 554 } 555 556 __shared_count& 557 operator=(const __shared_count& __r) noexcept 558 { 559 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 560 if (__tmp != _M_pi) 561 { 562 if (__tmp != 0) 563 __tmp->_M_add_ref_copy(); 564 if (_M_pi != 0) 565 _M_pi->_M_release(); 566 _M_pi = __tmp; 567 } 568 return *this; 569 } 570 571 void 572 _M_swap(__shared_count& __r) noexcept 573 { 574 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 575 __r._M_pi = _M_pi; 576 _M_pi = __tmp; 577 } 578 579 long 580 _M_get_use_count() const noexcept 581 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 582 583 bool 584 _M_unique() const noexcept 585 { return this->_M_get_use_count() == 1; } 586 587 void* 588 _M_get_deleter(const std::type_info& __ti) const noexcept 589 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } 590 591 bool 592 _M_less(const __shared_count& __rhs) const noexcept 593 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 594 595 bool 596 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 597 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 598 599 // Friend function injected into enclosing namespace and found by ADL 600 friend inline bool 601 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 602 { return __a._M_pi == __b._M_pi; } 603 604 private: 605 friend class __weak_count<_Lp>; 606 607 _Sp_counted_base<_Lp>* _M_pi; 608 }; 609 610 611 template<_Lock_policy _Lp> 612 class __weak_count 613 { 614 public: 615 constexpr __weak_count() noexcept : _M_pi(0) 616 { } 617 618 __weak_count(const __shared_count<_Lp>& __r) noexcept 619 : _M_pi(__r._M_pi) 620 { 621 if (_M_pi != 0) 622 _M_pi->_M_weak_add_ref(); 623 } 624 625 __weak_count(const __weak_count<_Lp>& __r) noexcept 626 : _M_pi(__r._M_pi) 627 { 628 if (_M_pi != 0) 629 _M_pi->_M_weak_add_ref(); 630 } 631 632 ~__weak_count() noexcept 633 { 634 if (_M_pi != 0) 635 _M_pi->_M_weak_release(); 636 } 637 638 __weak_count<_Lp>& 639 operator=(const __shared_count<_Lp>& __r) noexcept 640 { 641 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 642 if (__tmp != 0) 643 __tmp->_M_weak_add_ref(); 644 if (_M_pi != 0) 645 _M_pi->_M_weak_release(); 646 _M_pi = __tmp; 647 return *this; 648 } 649 650 __weak_count<_Lp>& 651 operator=(const __weak_count<_Lp>& __r) noexcept 652 { 653 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 654 if (__tmp != 0) 655 __tmp->_M_weak_add_ref(); 656 if (_M_pi != 0) 657 _M_pi->_M_weak_release(); 658 _M_pi = __tmp; 659 return *this; 660 } 661 662 void 663 _M_swap(__weak_count<_Lp>& __r) noexcept 664 { 665 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 666 __r._M_pi = _M_pi; 667 _M_pi = __tmp; 668 } 669 670 long 671 _M_get_use_count() const noexcept 672 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 673 674 bool 675 _M_less(const __weak_count& __rhs) const noexcept 676 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 677 678 bool 679 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 680 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 681 682 // Friend function injected into enclosing namespace and found by ADL 683 friend inline bool 684 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 685 { return __a._M_pi == __b._M_pi; } 686 687 private: 688 friend class __shared_count<_Lp>; 689 690 _Sp_counted_base<_Lp>* _M_pi; 691 }; 692 693 // Now that __weak_count is defined we can define this constructor: 694 template<_Lock_policy _Lp> 695 inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r) 696 : _M_pi(__r._M_pi) 697 { 698 if (_M_pi != 0) 699 _M_pi->_M_add_ref_lock(); 700 else 701 __throw_bad_weak_ptr(); 702 } 703 704 705 // Support for enable_shared_from_this. 706 707 // Friend of __enable_shared_from_this. 708 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2> 709 void 710 __enable_shared_from_this_helper(const __shared_count<_Lp>&, 711 const __enable_shared_from_this<_Tp1, 712 _Lp>*, const _Tp2*) noexcept; 713 714 // Friend of enable_shared_from_this. 715 template<typename _Tp1, typename _Tp2> 716 void 717 __enable_shared_from_this_helper(const __shared_count<>&, 718 const enable_shared_from_this<_Tp1>*, 719 const _Tp2*) noexcept; 720 721 template<_Lock_policy _Lp> 722 inline void 723 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept 724 { } 725 726 727 template<typename _Tp, _Lock_policy _Lp> 728 class __shared_ptr 729 { 730 public: 731 typedef _Tp element_type; 732 733 constexpr __shared_ptr() noexcept 734 : _M_ptr(0), _M_refcount() 735 { } 736 737 template<typename _Tp1> 738 explicit __shared_ptr(_Tp1* __p) 739 : _M_ptr(__p), _M_refcount(__p) 740 { 741 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 742 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 743 __enable_shared_from_this_helper(_M_refcount, __p, __p); 744 } 745 746 template<typename _Tp1, typename _Deleter> 747 __shared_ptr(_Tp1* __p, _Deleter __d) 748 : _M_ptr(__p), _M_refcount(__p, __d) 749 { 750 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 751 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 752 __enable_shared_from_this_helper(_M_refcount, __p, __p); 753 } 754 755 template<typename _Tp1, typename _Deleter, typename _Alloc> 756 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 757 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a)) 758 { 759 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 760 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 761 __enable_shared_from_this_helper(_M_refcount, __p, __p); 762 } 763 764 template<typename _Deleter> 765 __shared_ptr(nullptr_t __p, _Deleter __d) 766 : _M_ptr(0), _M_refcount(__p, __d) 767 { } 768 769 template<typename _Deleter, typename _Alloc> 770 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 771 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) 772 { } 773 774 template<typename _Tp1> 775 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) noexcept 776 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 777 { } 778 779 __shared_ptr(const __shared_ptr&) noexcept = default; 780 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 781 ~__shared_ptr() = default; 782 783 template<typename _Tp1, typename = typename 784 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 785 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 786 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 787 { } 788 789 __shared_ptr(__shared_ptr&& __r) noexcept 790 : _M_ptr(__r._M_ptr), _M_refcount() 791 { 792 _M_refcount._M_swap(__r._M_refcount); 793 __r._M_ptr = 0; 794 } 795 796 template<typename _Tp1, typename = typename 797 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 798 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 799 : _M_ptr(__r._M_ptr), _M_refcount() 800 { 801 _M_refcount._M_swap(__r._M_refcount); 802 __r._M_ptr = 0; 803 } 804 805 template<typename _Tp1> 806 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 807 : _M_refcount(__r._M_refcount) // may throw 808 { 809 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 810 811 // It is now safe to copy __r._M_ptr, as 812 // _M_refcount(__r._M_refcount) did not throw. 813 _M_ptr = __r._M_ptr; 814 } 815 816 // If an exception is thrown this constructor has no effect. 817 template<typename _Tp1, typename _Del> 818 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) 819 : _M_ptr(__r.get()), _M_refcount() 820 { 821 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 822 auto __tmp = __r.get(); 823 _M_refcount = __shared_count<_Lp>(std::move(__r)); 824 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); 825 } 826 827 #if _GLIBCXX_USE_DEPRECATED 828 // Postcondition: use_count() == 1 and __r.get() == 0 829 template<typename _Tp1> 830 __shared_ptr(std::auto_ptr<_Tp1>&& __r); 831 #endif 832 833 /* TODO: use delegating constructor */ 834 constexpr __shared_ptr(nullptr_t) noexcept 835 : _M_ptr(0), _M_refcount() 836 { } 837 838 template<typename _Tp1> 839 __shared_ptr& 840 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 841 { 842 _M_ptr = __r._M_ptr; 843 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 844 return *this; 845 } 846 847 #if _GLIBCXX_USE_DEPRECATED 848 template<typename _Tp1> 849 __shared_ptr& 850 operator=(std::auto_ptr<_Tp1>&& __r) 851 { 852 __shared_ptr(std::move(__r)).swap(*this); 853 return *this; 854 } 855 #endif 856 857 __shared_ptr& 858 operator=(__shared_ptr&& __r) noexcept 859 { 860 __shared_ptr(std::move(__r)).swap(*this); 861 return *this; 862 } 863 864 template<class _Tp1> 865 __shared_ptr& 866 operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 867 { 868 __shared_ptr(std::move(__r)).swap(*this); 869 return *this; 870 } 871 872 template<typename _Tp1, typename _Del> 873 __shared_ptr& 874 operator=(std::unique_ptr<_Tp1, _Del>&& __r) 875 { 876 __shared_ptr(std::move(__r)).swap(*this); 877 return *this; 878 } 879 880 void 881 reset() noexcept 882 { __shared_ptr().swap(*this); } 883 884 template<typename _Tp1> 885 void 886 reset(_Tp1* __p) // _Tp1 must be complete. 887 { 888 // Catch self-reset errors. 889 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); 890 __shared_ptr(__p).swap(*this); 891 } 892 893 template<typename _Tp1, typename _Deleter> 894 void 895 reset(_Tp1* __p, _Deleter __d) 896 { __shared_ptr(__p, __d).swap(*this); } 897 898 template<typename _Tp1, typename _Deleter, typename _Alloc> 899 void 900 reset(_Tp1* __p, _Deleter __d, _Alloc __a) 901 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); } 902 903 // Allow class instantiation when _Tp is [cv-qual] void. 904 typename std::add_lvalue_reference<_Tp>::type 905 operator*() const noexcept 906 { 907 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 908 return *_M_ptr; 909 } 910 911 _Tp* 912 operator->() const noexcept 913 { 914 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 915 return _M_ptr; 916 } 917 918 _Tp* 919 get() const noexcept 920 { return _M_ptr; } 921 922 explicit operator bool() const // never throws 923 { return _M_ptr == 0 ? false : true; } 924 925 bool 926 unique() const noexcept 927 { return _M_refcount._M_unique(); } 928 929 long 930 use_count() const noexcept 931 { return _M_refcount._M_get_use_count(); } 932 933 void 934 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 935 { 936 std::swap(_M_ptr, __other._M_ptr); 937 _M_refcount._M_swap(__other._M_refcount); 938 } 939 940 template<typename _Tp1> 941 bool 942 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const 943 { return _M_refcount._M_less(__rhs._M_refcount); } 944 945 template<typename _Tp1> 946 bool 947 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const 948 { return _M_refcount._M_less(__rhs._M_refcount); } 949 950 #ifdef __GXX_RTTI 951 protected: 952 // This constructor is non-standard, it is used by allocate_shared. 953 template<typename _Alloc, typename... _Args> 954 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 955 _Args&&... __args) 956 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 957 std::forward<_Args>(__args)...) 958 { 959 // _M_ptr needs to point to the newly constructed object. 960 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 961 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 962 _M_ptr = static_cast<_Tp*>(__p); 963 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 964 } 965 #else 966 template<typename _Alloc> 967 struct _Deleter 968 { 969 void operator()(_Tp* __ptr) 970 { 971 typedef allocator_traits<_Alloc> _Alloc_traits; 972 _Alloc_traits::destroy(_M_alloc, __ptr); 973 _Alloc_traits::deallocate(_M_alloc, __ptr, 1); 974 } 975 _Alloc _M_alloc; 976 }; 977 978 template<typename _Alloc, typename... _Args> 979 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 980 _Args&&... __args) 981 : _M_ptr(), _M_refcount() 982 { 983 typedef typename _Alloc::template rebind<_Tp>::other _Alloc2; 984 _Deleter<_Alloc2> __del = { _Alloc2(__a) }; 985 typedef allocator_traits<_Alloc2> __traits; 986 _M_ptr = __traits::allocate(__del._M_alloc, 1); 987 __try 988 { 989 // _GLIBCXX_RESOLVE_LIB_DEFECTS 990 // 2070. allocate_shared should use allocator_traits<A>::construct 991 __traits::construct(__del._M_alloc, _M_ptr, 992 std::forward<_Args>(__args)...); 993 } 994 __catch(...) 995 { 996 __traits::deallocate(__del._M_alloc, _M_ptr, 1); 997 __throw_exception_again; 998 } 999 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc); 1000 _M_refcount._M_swap(__count); 1001 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 1002 } 1003 #endif 1004 1005 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1006 typename... _Args> 1007 friend __shared_ptr<_Tp1, _Lp1> 1008 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1009 1010 private: 1011 void* 1012 _M_get_deleter(const std::type_info& __ti) const noexcept 1013 { return _M_refcount._M_get_deleter(__ti); } 1014 1015 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1016 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1017 1018 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1019 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 1020 1021 _Tp* _M_ptr; // Contained pointer. 1022 __shared_count<_Lp> _M_refcount; // Reference counter. 1023 }; 1024 1025 1026 // 20.7.2.2.7 shared_ptr comparisons 1027 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1028 inline bool 1029 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1030 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1031 { return __a.get() == __b.get(); } 1032 1033 template<typename _Tp, _Lock_policy _Lp> 1034 inline bool 1035 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1036 { return !__a; } 1037 1038 template<typename _Tp, _Lock_policy _Lp> 1039 inline bool 1040 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1041 { return !__a; } 1042 1043 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1044 inline bool 1045 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1046 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1047 { return __a.get() != __b.get(); } 1048 1049 template<typename _Tp, _Lock_policy _Lp> 1050 inline bool 1051 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1052 { return (bool)__a; } 1053 1054 template<typename _Tp, _Lock_policy _Lp> 1055 inline bool 1056 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1057 { return (bool)__a; } 1058 1059 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1060 inline bool 1061 operator<(const __shared_ptr<_Tp1, _Lp>& __a, 1062 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1063 { 1064 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT; 1065 return std::less<_CT>()(__a.get(), __b.get()); 1066 } 1067 1068 template<typename _Tp, _Lock_policy _Lp> 1069 inline bool 1070 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1071 { return std::less<_Tp*>()(__a.get(), nullptr); } 1072 1073 template<typename _Tp, _Lock_policy _Lp> 1074 inline bool 1075 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1076 { return std::less<_Tp*>()(nullptr, __a.get()); } 1077 1078 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1079 inline bool 1080 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 1081 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1082 { return !(__b < __a); } 1083 1084 template<typename _Tp, _Lock_policy _Lp> 1085 inline bool 1086 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1087 { return !(nullptr < __a); } 1088 1089 template<typename _Tp, _Lock_policy _Lp> 1090 inline bool 1091 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1092 { return !(__a < nullptr); } 1093 1094 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1095 inline bool 1096 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 1097 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1098 { return (__b < __a); } 1099 1100 template<typename _Tp, _Lock_policy _Lp> 1101 inline bool 1102 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1103 { return std::less<_Tp*>()(nullptr, __a.get()); } 1104 1105 template<typename _Tp, _Lock_policy _Lp> 1106 inline bool 1107 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1108 { return std::less<_Tp*>()(__a.get(), nullptr); } 1109 1110 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1111 inline bool 1112 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 1113 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1114 { return !(__a < __b); } 1115 1116 template<typename _Tp, _Lock_policy _Lp> 1117 inline bool 1118 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1119 { return !(__a < nullptr); } 1120 1121 template<typename _Tp, _Lock_policy _Lp> 1122 inline bool 1123 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1124 { return !(nullptr < __a); } 1125 1126 template<typename _Sp> 1127 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1128 { 1129 bool 1130 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 1131 { 1132 typedef typename _Sp::element_type element_type; 1133 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1134 } 1135 }; 1136 1137 template<typename _Tp, _Lock_policy _Lp> 1138 struct less<__shared_ptr<_Tp, _Lp>> 1139 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1140 { }; 1141 1142 // 2.2.3.8 shared_ptr specialized algorithms. 1143 template<typename _Tp, _Lock_policy _Lp> 1144 inline void 1145 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 1146 { __a.swap(__b); } 1147 1148 // 2.2.3.9 shared_ptr casts 1149 1150 // The seemingly equivalent code: 1151 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1152 // will eventually result in undefined behaviour, attempting to 1153 // delete the same object twice. 1154 /// static_pointer_cast 1155 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1156 inline __shared_ptr<_Tp, _Lp> 1157 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1158 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); } 1159 1160 // The seemingly equivalent code: 1161 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1162 // will eventually result in undefined behaviour, attempting to 1163 // delete the same object twice. 1164 /// const_pointer_cast 1165 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1166 inline __shared_ptr<_Tp, _Lp> 1167 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1168 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); } 1169 1170 // The seemingly equivalent code: 1171 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1172 // will eventually result in undefined behaviour, attempting to 1173 // delete the same object twice. 1174 /// dynamic_pointer_cast 1175 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1176 inline __shared_ptr<_Tp, _Lp> 1177 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1178 { 1179 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) 1180 return __shared_ptr<_Tp, _Lp>(__r, __p); 1181 return __shared_ptr<_Tp, _Lp>(); 1182 } 1183 1184 1185 template<typename _Tp, _Lock_policy _Lp> 1186 class __weak_ptr 1187 { 1188 public: 1189 typedef _Tp element_type; 1190 1191 constexpr __weak_ptr() noexcept 1192 : _M_ptr(0), _M_refcount() 1193 { } 1194 1195 __weak_ptr(const __weak_ptr&) noexcept = default; 1196 __weak_ptr& operator=(const __weak_ptr&) noexcept = default; 1197 ~__weak_ptr() = default; 1198 1199 // The "obvious" converting constructor implementation: 1200 // 1201 // template<typename _Tp1> 1202 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1203 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1204 // { } 1205 // 1206 // has a serious problem. 1207 // 1208 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1209 // conversion may require access to *__r._M_ptr (virtual inheritance). 1210 // 1211 // It is not possible to avoid spurious access violations since 1212 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1213 template<typename _Tp1, typename = typename 1214 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1215 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1216 : _M_refcount(__r._M_refcount) 1217 { _M_ptr = __r.lock().get(); } 1218 1219 template<typename _Tp1, typename = typename 1220 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1221 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1222 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1223 { } 1224 1225 template<typename _Tp1> 1226 __weak_ptr& 1227 operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1228 { 1229 _M_ptr = __r.lock().get(); 1230 _M_refcount = __r._M_refcount; 1231 return *this; 1232 } 1233 1234 template<typename _Tp1> 1235 __weak_ptr& 1236 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1237 { 1238 _M_ptr = __r._M_ptr; 1239 _M_refcount = __r._M_refcount; 1240 return *this; 1241 } 1242 1243 __shared_ptr<_Tp, _Lp> 1244 lock() const noexcept 1245 { 1246 #ifdef __GTHREADS 1247 // Optimization: avoid throw overhead. 1248 if (expired()) 1249 return __shared_ptr<element_type, _Lp>(); 1250 1251 __try 1252 { 1253 return __shared_ptr<element_type, _Lp>(*this); 1254 } 1255 __catch(const bad_weak_ptr&) 1256 { 1257 // Q: How can we get here? 1258 // A: Another thread may have invalidated r after the 1259 // use_count test above. 1260 return __shared_ptr<element_type, _Lp>(); 1261 } 1262 1263 #else 1264 // Optimization: avoid try/catch overhead when single threaded. 1265 return expired() ? __shared_ptr<element_type, _Lp>() 1266 : __shared_ptr<element_type, _Lp>(*this); 1267 1268 #endif 1269 } // XXX MT 1270 1271 long 1272 use_count() const noexcept 1273 { return _M_refcount._M_get_use_count(); } 1274 1275 bool 1276 expired() const noexcept 1277 { return _M_refcount._M_get_use_count() == 0; } 1278 1279 template<typename _Tp1> 1280 bool 1281 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const 1282 { return _M_refcount._M_less(__rhs._M_refcount); } 1283 1284 template<typename _Tp1> 1285 bool 1286 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const 1287 { return _M_refcount._M_less(__rhs._M_refcount); } 1288 1289 void 1290 reset() noexcept 1291 { __weak_ptr().swap(*this); } 1292 1293 void 1294 swap(__weak_ptr& __s) noexcept 1295 { 1296 std::swap(_M_ptr, __s._M_ptr); 1297 _M_refcount._M_swap(__s._M_refcount); 1298 } 1299 1300 private: 1301 // Used by __enable_shared_from_this. 1302 void 1303 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 1304 { 1305 _M_ptr = __ptr; 1306 _M_refcount = __refcount; 1307 } 1308 1309 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1310 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1311 friend class __enable_shared_from_this<_Tp, _Lp>; 1312 friend class enable_shared_from_this<_Tp>; 1313 1314 _Tp* _M_ptr; // Contained pointer. 1315 __weak_count<_Lp> _M_refcount; // Reference counter. 1316 }; 1317 1318 // 20.7.2.3.6 weak_ptr specialized algorithms. 1319 template<typename _Tp, _Lock_policy _Lp> 1320 inline void 1321 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 1322 { __a.swap(__b); } 1323 1324 template<typename _Tp, typename _Tp1> 1325 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1326 { 1327 bool 1328 operator()(const _Tp& __lhs, const _Tp& __rhs) const 1329 { return __lhs.owner_before(__rhs); } 1330 1331 bool 1332 operator()(const _Tp& __lhs, const _Tp1& __rhs) const 1333 { return __lhs.owner_before(__rhs); } 1334 1335 bool 1336 operator()(const _Tp1& __lhs, const _Tp& __rhs) const 1337 { return __lhs.owner_before(__rhs); } 1338 }; 1339 1340 template<typename _Tp, _Lock_policy _Lp> 1341 struct owner_less<__shared_ptr<_Tp, _Lp>> 1342 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1343 { }; 1344 1345 template<typename _Tp, _Lock_policy _Lp> 1346 struct owner_less<__weak_ptr<_Tp, _Lp>> 1347 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1348 { }; 1349 1350 1351 template<typename _Tp, _Lock_policy _Lp> 1352 class __enable_shared_from_this 1353 { 1354 protected: 1355 constexpr __enable_shared_from_this() noexcept { } 1356 1357 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 1358 1359 __enable_shared_from_this& 1360 operator=(const __enable_shared_from_this&) noexcept 1361 { return *this; } 1362 1363 ~__enable_shared_from_this() { } 1364 1365 public: 1366 __shared_ptr<_Tp, _Lp> 1367 shared_from_this() 1368 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1369 1370 __shared_ptr<const _Tp, _Lp> 1371 shared_from_this() const 1372 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1373 1374 private: 1375 template<typename _Tp1> 1376 void 1377 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 1378 { _M_weak_this._M_assign(__p, __n); } 1379 1380 template<typename _Tp1> 1381 friend void 1382 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn, 1383 const __enable_shared_from_this* __pe, 1384 const _Tp1* __px) noexcept 1385 { 1386 if (__pe != 0) 1387 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); 1388 } 1389 1390 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1391 }; 1392 1393 1394 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1395 inline __shared_ptr<_Tp, _Lp> 1396 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1397 { 1398 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1399 std::forward<_Args>(__args)...); 1400 } 1401 1402 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1403 inline __shared_ptr<_Tp, _Lp> 1404 __make_shared(_Args&&... __args) 1405 { 1406 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1407 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1408 std::forward<_Args>(__args)...); 1409 } 1410 1411 /// std::hash specialization for __shared_ptr. 1412 template<typename _Tp, _Lock_policy _Lp> 1413 struct hash<__shared_ptr<_Tp, _Lp>> 1414 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 1415 { 1416 size_t 1417 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1418 { return std::hash<_Tp*>()(__s.get()); } 1419 }; 1420 1421 _GLIBCXX_END_NAMESPACE_VERSION 1422 } // namespace 1423 1424 #endif // _SHARED_PTR_BASE_H 1425
