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_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), _M_storage() 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) : _M_pi(0) 463 { 464 // The allocator's value_type doesn't matter, will rebind it anyway. 465 typedef std::allocator<int> _Alloc; 466 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 467 typedef typename allocator_traits<_Alloc>::template 468 rebind_traits<_Sp_cd_type> _Alloc_traits; 469 typename _Alloc_traits::allocator_type __a; 470 _Sp_cd_type* __mem = 0; 471 __try 472 { 473 __mem = _Alloc_traits::allocate(__a, 1); 474 _Alloc_traits::construct(__a, __mem, __p, std::move(__d)); 475 _M_pi = __mem; 476 } 477 __catch(...) 478 { 479 __d(__p); // Call _Deleter on __p. 480 if (__mem) 481 _Alloc_traits::deallocate(__a, __mem, 1); 482 __throw_exception_again; 483 } 484 } 485 486 template<typename _Ptr, typename _Deleter, typename _Alloc> 487 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 488 { 489 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 490 typedef typename allocator_traits<_Alloc>::template 491 rebind_traits<_Sp_cd_type> _Alloc_traits; 492 typename _Alloc_traits::allocator_type __a2(__a); 493 _Sp_cd_type* __mem = 0; 494 __try 495 { 496 __mem = _Alloc_traits::allocate(__a2, 1); 497 _Alloc_traits::construct(__a2, __mem, 498 __p, std::move(__d), std::move(__a)); 499 _M_pi = __mem; 500 } 501 __catch(...) 502 { 503 __d(__p); // Call _Deleter on __p. 504 if (__mem) 505 _Alloc_traits::deallocate(__a2, __mem, 1); 506 __throw_exception_again; 507 } 508 } 509 510 template<typename _Tp, typename _Alloc, typename... _Args> 511 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 512 _Args&&... __args) 513 : _M_pi(0) 514 { 515 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 516 typedef typename allocator_traits<_Alloc>::template 517 rebind_traits<_Sp_cp_type> _Alloc_traits; 518 typename _Alloc_traits::allocator_type __a2(__a); 519 _Sp_cp_type* __mem = _Alloc_traits::allocate(__a2, 1); 520 __try 521 { 522 _Alloc_traits::construct(__a2, __mem, std::move(__a), 523 std::forward<_Args>(__args)...); 524 _M_pi = __mem; 525 } 526 __catch(...) 527 { 528 _Alloc_traits::deallocate(__a2, __mem, 1); 529 __throw_exception_again; 530 } 531 } 532 533 #if _GLIBCXX_USE_DEPRECATED 534 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 535 template<typename _Tp> 536 explicit 537 __shared_count(std::auto_ptr<_Tp>&& __r); 538 #endif 539 540 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 541 template<typename _Tp, typename _Del> 542 explicit 543 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) 544 : _M_pi(_S_create_from_up(std::move(__r))) 545 { __r.release(); } 546 547 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 548 explicit __shared_count(const __weak_count<_Lp>& __r); 549 550 ~__shared_count() noexcept 551 { 552 if (_M_pi != 0) 553 _M_pi->_M_release(); 554 } 555 556 __shared_count(const __shared_count& __r) noexcept 557 : _M_pi(__r._M_pi) 558 { 559 if (_M_pi != 0) 560 _M_pi->_M_add_ref_copy(); 561 } 562 563 __shared_count& 564 operator=(const __shared_count& __r) noexcept 565 { 566 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 567 if (__tmp != _M_pi) 568 { 569 if (__tmp != 0) 570 __tmp->_M_add_ref_copy(); 571 if (_M_pi != 0) 572 _M_pi->_M_release(); 573 _M_pi = __tmp; 574 } 575 return *this; 576 } 577 578 void 579 _M_swap(__shared_count& __r) noexcept 580 { 581 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 582 __r._M_pi = _M_pi; 583 _M_pi = __tmp; 584 } 585 586 long 587 _M_get_use_count() const noexcept 588 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 589 590 bool 591 _M_unique() const noexcept 592 { return this->_M_get_use_count() == 1; } 593 594 void* 595 _M_get_deleter(const std::type_info& __ti) const noexcept 596 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } 597 598 bool 599 _M_less(const __shared_count& __rhs) const noexcept 600 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 601 602 bool 603 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 604 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 605 606 // Friend function injected into enclosing namespace and found by ADL 607 friend inline bool 608 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 609 { return __a._M_pi == __b._M_pi; } 610 611 private: 612 friend class __weak_count<_Lp>; 613 614 template<typename _Tp, typename _Del> 615 static _Sp_counted_base<_Lp>* 616 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 617 typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0) 618 { 619 typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr; 620 return new _Sp_counted_deleter<_Ptr, _Del, std::allocator<void>, 621 _Lp>(__r.get(), __r.get_deleter()); 622 } 623 624 template<typename _Tp, typename _Del> 625 static _Sp_counted_base<_Lp>* 626 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 627 typename std::enable_if<std::is_reference<_Del>::value>::type* = 0) 628 { 629 typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr; 630 typedef typename std::remove_reference<_Del>::type _Del1; 631 typedef std::reference_wrapper<_Del1> _Del2; 632 return new _Sp_counted_deleter<_Ptr, _Del2, std::allocator<void>, 633 _Lp>(__r.get(), std::ref(__r.get_deleter())); 634 } 635 636 _Sp_counted_base<_Lp>* _M_pi; 637 }; 638 639 640 template<_Lock_policy _Lp> 641 class __weak_count 642 { 643 public: 644 constexpr __weak_count() noexcept : _M_pi(0) 645 { } 646 647 __weak_count(const __shared_count<_Lp>& __r) noexcept 648 : _M_pi(__r._M_pi) 649 { 650 if (_M_pi != 0) 651 _M_pi->_M_weak_add_ref(); 652 } 653 654 __weak_count(const __weak_count<_Lp>& __r) noexcept 655 : _M_pi(__r._M_pi) 656 { 657 if (_M_pi != 0) 658 _M_pi->_M_weak_add_ref(); 659 } 660 661 ~__weak_count() noexcept 662 { 663 if (_M_pi != 0) 664 _M_pi->_M_weak_release(); 665 } 666 667 __weak_count<_Lp>& 668 operator=(const __shared_count<_Lp>& __r) noexcept 669 { 670 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 671 if (__tmp != 0) 672 __tmp->_M_weak_add_ref(); 673 if (_M_pi != 0) 674 _M_pi->_M_weak_release(); 675 _M_pi = __tmp; 676 return *this; 677 } 678 679 __weak_count<_Lp>& 680 operator=(const __weak_count<_Lp>& __r) noexcept 681 { 682 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 683 if (__tmp != 0) 684 __tmp->_M_weak_add_ref(); 685 if (_M_pi != 0) 686 _M_pi->_M_weak_release(); 687 _M_pi = __tmp; 688 return *this; 689 } 690 691 void 692 _M_swap(__weak_count<_Lp>& __r) noexcept 693 { 694 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 695 __r._M_pi = _M_pi; 696 _M_pi = __tmp; 697 } 698 699 long 700 _M_get_use_count() const noexcept 701 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 702 703 bool 704 _M_less(const __weak_count& __rhs) const noexcept 705 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 706 707 bool 708 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 709 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 710 711 // Friend function injected into enclosing namespace and found by ADL 712 friend inline bool 713 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 714 { return __a._M_pi == __b._M_pi; } 715 716 private: 717 friend class __shared_count<_Lp>; 718 719 _Sp_counted_base<_Lp>* _M_pi; 720 }; 721 722 // Now that __weak_count is defined we can define this constructor: 723 template<_Lock_policy _Lp> 724 inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r) 725 : _M_pi(__r._M_pi) 726 { 727 if (_M_pi != 0) 728 _M_pi->_M_add_ref_lock(); 729 else 730 __throw_bad_weak_ptr(); 731 } 732 733 734 // Support for enable_shared_from_this. 735 736 // Friend of __enable_shared_from_this. 737 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2> 738 void 739 __enable_shared_from_this_helper(const __shared_count<_Lp>&, 740 const __enable_shared_from_this<_Tp1, 741 _Lp>*, const _Tp2*) noexcept; 742 743 // Friend of enable_shared_from_this. 744 template<typename _Tp1, typename _Tp2> 745 void 746 __enable_shared_from_this_helper(const __shared_count<>&, 747 const enable_shared_from_this<_Tp1>*, 748 const _Tp2*) noexcept; 749 750 template<_Lock_policy _Lp> 751 inline void 752 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept 753 { } 754 755 756 template<typename _Tp, _Lock_policy _Lp> 757 class __shared_ptr 758 { 759 public: 760 typedef _Tp element_type; 761 762 constexpr __shared_ptr() noexcept 763 : _M_ptr(0), _M_refcount() 764 { } 765 766 template<typename _Tp1> 767 explicit __shared_ptr(_Tp1* __p) 768 : _M_ptr(__p), _M_refcount(__p) 769 { 770 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 771 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 772 __enable_shared_from_this_helper(_M_refcount, __p, __p); 773 } 774 775 template<typename _Tp1, typename _Deleter> 776 __shared_ptr(_Tp1* __p, _Deleter __d) 777 : _M_ptr(__p), _M_refcount(__p, __d) 778 { 779 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 780 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 781 __enable_shared_from_this_helper(_M_refcount, __p, __p); 782 } 783 784 template<typename _Tp1, typename _Deleter, typename _Alloc> 785 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 786 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a)) 787 { 788 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 789 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 790 __enable_shared_from_this_helper(_M_refcount, __p, __p); 791 } 792 793 template<typename _Deleter> 794 __shared_ptr(nullptr_t __p, _Deleter __d) 795 : _M_ptr(0), _M_refcount(__p, __d) 796 { } 797 798 template<typename _Deleter, typename _Alloc> 799 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 800 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) 801 { } 802 803 template<typename _Tp1> 804 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) noexcept 805 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 806 { } 807 808 __shared_ptr(const __shared_ptr&) noexcept = default; 809 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 810 ~__shared_ptr() = default; 811 812 template<typename _Tp1, typename = typename 813 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 814 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 815 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 816 { } 817 818 __shared_ptr(__shared_ptr&& __r) noexcept 819 : _M_ptr(__r._M_ptr), _M_refcount() 820 { 821 _M_refcount._M_swap(__r._M_refcount); 822 __r._M_ptr = 0; 823 } 824 825 template<typename _Tp1, typename = typename 826 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 827 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 828 : _M_ptr(__r._M_ptr), _M_refcount() 829 { 830 _M_refcount._M_swap(__r._M_refcount); 831 __r._M_ptr = 0; 832 } 833 834 template<typename _Tp1> 835 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 836 : _M_refcount(__r._M_refcount) // may throw 837 { 838 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 839 840 // It is now safe to copy __r._M_ptr, as 841 // _M_refcount(__r._M_refcount) did not throw. 842 _M_ptr = __r._M_ptr; 843 } 844 845 // If an exception is thrown this constructor has no effect. 846 template<typename _Tp1, typename _Del> 847 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) 848 : _M_ptr(__r.get()), _M_refcount() 849 { 850 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 851 auto __tmp = std::__addressof(*__r.get()); 852 _M_refcount = __shared_count<_Lp>(std::move(__r)); 853 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); 854 } 855 856 #if _GLIBCXX_USE_DEPRECATED 857 // Postcondition: use_count() == 1 and __r.get() == 0 858 template<typename _Tp1> 859 __shared_ptr(std::auto_ptr<_Tp1>&& __r); 860 #endif 861 862 /* TODO: use delegating constructor */ 863 constexpr __shared_ptr(nullptr_t) noexcept 864 : _M_ptr(0), _M_refcount() 865 { } 866 867 template<typename _Tp1> 868 __shared_ptr& 869 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 870 { 871 _M_ptr = __r._M_ptr; 872 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 873 return *this; 874 } 875 876 #if _GLIBCXX_USE_DEPRECATED 877 template<typename _Tp1> 878 __shared_ptr& 879 operator=(std::auto_ptr<_Tp1>&& __r) 880 { 881 __shared_ptr(std::move(__r)).swap(*this); 882 return *this; 883 } 884 #endif 885 886 __shared_ptr& 887 operator=(__shared_ptr&& __r) noexcept 888 { 889 __shared_ptr(std::move(__r)).swap(*this); 890 return *this; 891 } 892 893 template<class _Tp1> 894 __shared_ptr& 895 operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 896 { 897 __shared_ptr(std::move(__r)).swap(*this); 898 return *this; 899 } 900 901 template<typename _Tp1, typename _Del> 902 __shared_ptr& 903 operator=(std::unique_ptr<_Tp1, _Del>&& __r) 904 { 905 __shared_ptr(std::move(__r)).swap(*this); 906 return *this; 907 } 908 909 void 910 reset() noexcept 911 { __shared_ptr().swap(*this); } 912 913 template<typename _Tp1> 914 void 915 reset(_Tp1* __p) // _Tp1 must be complete. 916 { 917 // Catch self-reset errors. 918 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); 919 __shared_ptr(__p).swap(*this); 920 } 921 922 template<typename _Tp1, typename _Deleter> 923 void 924 reset(_Tp1* __p, _Deleter __d) 925 { __shared_ptr(__p, __d).swap(*this); } 926 927 template<typename _Tp1, typename _Deleter, typename _Alloc> 928 void 929 reset(_Tp1* __p, _Deleter __d, _Alloc __a) 930 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); } 931 932 // Allow class instantiation when _Tp is [cv-qual] void. 933 typename std::add_lvalue_reference<_Tp>::type 934 operator*() const noexcept 935 { 936 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 937 return *_M_ptr; 938 } 939 940 _Tp* 941 operator->() const noexcept 942 { 943 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 944 return _M_ptr; 945 } 946 947 _Tp* 948 get() const noexcept 949 { return _M_ptr; } 950 951 explicit operator bool() const // never throws 952 { return _M_ptr == 0 ? false : true; } 953 954 bool 955 unique() const noexcept 956 { return _M_refcount._M_unique(); } 957 958 long 959 use_count() const noexcept 960 { return _M_refcount._M_get_use_count(); } 961 962 void 963 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 964 { 965 std::swap(_M_ptr, __other._M_ptr); 966 _M_refcount._M_swap(__other._M_refcount); 967 } 968 969 template<typename _Tp1> 970 bool 971 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const 972 { return _M_refcount._M_less(__rhs._M_refcount); } 973 974 template<typename _Tp1> 975 bool 976 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const 977 { return _M_refcount._M_less(__rhs._M_refcount); } 978 979 #ifdef __GXX_RTTI 980 protected: 981 // This constructor is non-standard, it is used by allocate_shared. 982 template<typename _Alloc, typename... _Args> 983 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 984 _Args&&... __args) 985 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 986 std::forward<_Args>(__args)...) 987 { 988 // _M_ptr needs to point to the newly constructed object. 989 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 990 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 991 _M_ptr = static_cast<_Tp*>(__p); 992 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 993 } 994 #else 995 template<typename _Alloc> 996 struct _Deleter 997 { 998 void operator()(_Tp* __ptr) 999 { 1000 typedef allocator_traits<_Alloc> _Alloc_traits; 1001 _Alloc_traits::destroy(_M_alloc, __ptr); 1002 _Alloc_traits::deallocate(_M_alloc, __ptr, 1); 1003 } 1004 _Alloc _M_alloc; 1005 }; 1006 1007 template<typename _Alloc, typename... _Args> 1008 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1009 _Args&&... __args) 1010 : _M_ptr(), _M_refcount() 1011 { 1012 typedef typename _Alloc::template rebind<_Tp>::other _Alloc2; 1013 _Deleter<_Alloc2> __del = { _Alloc2(__a) }; 1014 typedef allocator_traits<_Alloc2> __traits; 1015 _M_ptr = __traits::allocate(__del._M_alloc, 1); 1016 __try 1017 { 1018 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1019 // 2070. allocate_shared should use allocator_traits<A>::construct 1020 __traits::construct(__del._M_alloc, _M_ptr, 1021 std::forward<_Args>(__args)...); 1022 } 1023 __catch(...) 1024 { 1025 __traits::deallocate(__del._M_alloc, _M_ptr, 1); 1026 __throw_exception_again; 1027 } 1028 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc); 1029 _M_refcount._M_swap(__count); 1030 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 1031 } 1032 #endif 1033 1034 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1035 typename... _Args> 1036 friend __shared_ptr<_Tp1, _Lp1> 1037 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1038 1039 private: 1040 void* 1041 _M_get_deleter(const std::type_info& __ti) const noexcept 1042 { return _M_refcount._M_get_deleter(__ti); } 1043 1044 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1045 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1046 1047 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1048 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 1049 1050 _Tp* _M_ptr; // Contained pointer. 1051 __shared_count<_Lp> _M_refcount; // Reference counter. 1052 }; 1053 1054 1055 // 20.7.2.2.7 shared_ptr comparisons 1056 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1057 inline bool 1058 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1059 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1060 { return __a.get() == __b.get(); } 1061 1062 template<typename _Tp, _Lock_policy _Lp> 1063 inline bool 1064 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1065 { return !__a; } 1066 1067 template<typename _Tp, _Lock_policy _Lp> 1068 inline bool 1069 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1070 { return !__a; } 1071 1072 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1073 inline bool 1074 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1075 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1076 { return __a.get() != __b.get(); } 1077 1078 template<typename _Tp, _Lock_policy _Lp> 1079 inline bool 1080 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1081 { return (bool)__a; } 1082 1083 template<typename _Tp, _Lock_policy _Lp> 1084 inline bool 1085 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1086 { return (bool)__a; } 1087 1088 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1089 inline bool 1090 operator<(const __shared_ptr<_Tp1, _Lp>& __a, 1091 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1092 { 1093 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT; 1094 return std::less<_CT>()(__a.get(), __b.get()); 1095 } 1096 1097 template<typename _Tp, _Lock_policy _Lp> 1098 inline bool 1099 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1100 { return std::less<_Tp*>()(__a.get(), nullptr); } 1101 1102 template<typename _Tp, _Lock_policy _Lp> 1103 inline bool 1104 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1105 { return std::less<_Tp*>()(nullptr, __a.get()); } 1106 1107 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1108 inline bool 1109 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 1110 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1111 { return !(__b < __a); } 1112 1113 template<typename _Tp, _Lock_policy _Lp> 1114 inline bool 1115 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1116 { return !(nullptr < __a); } 1117 1118 template<typename _Tp, _Lock_policy _Lp> 1119 inline bool 1120 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1121 { return !(__a < nullptr); } 1122 1123 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1124 inline bool 1125 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 1126 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1127 { return (__b < __a); } 1128 1129 template<typename _Tp, _Lock_policy _Lp> 1130 inline bool 1131 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1132 { return std::less<_Tp*>()(nullptr, __a.get()); } 1133 1134 template<typename _Tp, _Lock_policy _Lp> 1135 inline bool 1136 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1137 { return std::less<_Tp*>()(__a.get(), nullptr); } 1138 1139 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1140 inline bool 1141 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 1142 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1143 { return !(__a < __b); } 1144 1145 template<typename _Tp, _Lock_policy _Lp> 1146 inline bool 1147 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1148 { return !(__a < nullptr); } 1149 1150 template<typename _Tp, _Lock_policy _Lp> 1151 inline bool 1152 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1153 { return !(nullptr < __a); } 1154 1155 template<typename _Sp> 1156 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1157 { 1158 bool 1159 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 1160 { 1161 typedef typename _Sp::element_type element_type; 1162 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1163 } 1164 }; 1165 1166 template<typename _Tp, _Lock_policy _Lp> 1167 struct less<__shared_ptr<_Tp, _Lp>> 1168 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1169 { }; 1170 1171 // 2.2.3.8 shared_ptr specialized algorithms. 1172 template<typename _Tp, _Lock_policy _Lp> 1173 inline void 1174 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 1175 { __a.swap(__b); } 1176 1177 // 2.2.3.9 shared_ptr casts 1178 1179 // The seemingly equivalent code: 1180 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1181 // will eventually result in undefined behaviour, attempting to 1182 // delete the same object twice. 1183 /// static_pointer_cast 1184 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1185 inline __shared_ptr<_Tp, _Lp> 1186 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1187 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); } 1188 1189 // The seemingly equivalent code: 1190 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1191 // will eventually result in undefined behaviour, attempting to 1192 // delete the same object twice. 1193 /// const_pointer_cast 1194 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1195 inline __shared_ptr<_Tp, _Lp> 1196 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1197 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); } 1198 1199 // The seemingly equivalent code: 1200 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1201 // will eventually result in undefined behaviour, attempting to 1202 // delete the same object twice. 1203 /// dynamic_pointer_cast 1204 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1205 inline __shared_ptr<_Tp, _Lp> 1206 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1207 { 1208 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) 1209 return __shared_ptr<_Tp, _Lp>(__r, __p); 1210 return __shared_ptr<_Tp, _Lp>(); 1211 } 1212 1213 1214 template<typename _Tp, _Lock_policy _Lp> 1215 class __weak_ptr 1216 { 1217 public: 1218 typedef _Tp element_type; 1219 1220 constexpr __weak_ptr() noexcept 1221 : _M_ptr(0), _M_refcount() 1222 { } 1223 1224 __weak_ptr(const __weak_ptr&) noexcept = default; 1225 __weak_ptr& operator=(const __weak_ptr&) noexcept = default; 1226 ~__weak_ptr() = default; 1227 1228 // The "obvious" converting constructor implementation: 1229 // 1230 // template<typename _Tp1> 1231 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1232 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1233 // { } 1234 // 1235 // has a serious problem. 1236 // 1237 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1238 // conversion may require access to *__r._M_ptr (virtual inheritance). 1239 // 1240 // It is not possible to avoid spurious access violations since 1241 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1242 template<typename _Tp1, typename = typename 1243 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1244 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1245 : _M_refcount(__r._M_refcount) 1246 { _M_ptr = __r.lock().get(); } 1247 1248 template<typename _Tp1, typename = typename 1249 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1250 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1251 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1252 { } 1253 1254 template<typename _Tp1> 1255 __weak_ptr& 1256 operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1257 { 1258 _M_ptr = __r.lock().get(); 1259 _M_refcount = __r._M_refcount; 1260 return *this; 1261 } 1262 1263 template<typename _Tp1> 1264 __weak_ptr& 1265 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1266 { 1267 _M_ptr = __r._M_ptr; 1268 _M_refcount = __r._M_refcount; 1269 return *this; 1270 } 1271 1272 __shared_ptr<_Tp, _Lp> 1273 lock() const noexcept 1274 { 1275 #ifdef __GTHREADS 1276 // Optimization: avoid throw overhead. 1277 if (expired()) 1278 return __shared_ptr<element_type, _Lp>(); 1279 1280 __try 1281 { 1282 return __shared_ptr<element_type, _Lp>(*this); 1283 } 1284 __catch(const bad_weak_ptr&) 1285 { 1286 // Q: How can we get here? 1287 // A: Another thread may have invalidated r after the 1288 // use_count test above. 1289 return __shared_ptr<element_type, _Lp>(); 1290 } 1291 1292 #else 1293 // Optimization: avoid try/catch overhead when single threaded. 1294 return expired() ? __shared_ptr<element_type, _Lp>() 1295 : __shared_ptr<element_type, _Lp>(*this); 1296 1297 #endif 1298 } // XXX MT 1299 1300 long 1301 use_count() const noexcept 1302 { return _M_refcount._M_get_use_count(); } 1303 1304 bool 1305 expired() const noexcept 1306 { return _M_refcount._M_get_use_count() == 0; } 1307 1308 template<typename _Tp1> 1309 bool 1310 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const 1311 { return _M_refcount._M_less(__rhs._M_refcount); } 1312 1313 template<typename _Tp1> 1314 bool 1315 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const 1316 { return _M_refcount._M_less(__rhs._M_refcount); } 1317 1318 void 1319 reset() noexcept 1320 { __weak_ptr().swap(*this); } 1321 1322 void 1323 swap(__weak_ptr& __s) noexcept 1324 { 1325 std::swap(_M_ptr, __s._M_ptr); 1326 _M_refcount._M_swap(__s._M_refcount); 1327 } 1328 1329 private: 1330 // Used by __enable_shared_from_this. 1331 void 1332 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 1333 { 1334 _M_ptr = __ptr; 1335 _M_refcount = __refcount; 1336 } 1337 1338 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1339 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1340 friend class __enable_shared_from_this<_Tp, _Lp>; 1341 friend class enable_shared_from_this<_Tp>; 1342 1343 _Tp* _M_ptr; // Contained pointer. 1344 __weak_count<_Lp> _M_refcount; // Reference counter. 1345 }; 1346 1347 // 20.7.2.3.6 weak_ptr specialized algorithms. 1348 template<typename _Tp, _Lock_policy _Lp> 1349 inline void 1350 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 1351 { __a.swap(__b); } 1352 1353 template<typename _Tp, typename _Tp1> 1354 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1355 { 1356 bool 1357 operator()(const _Tp& __lhs, const _Tp& __rhs) const 1358 { return __lhs.owner_before(__rhs); } 1359 1360 bool 1361 operator()(const _Tp& __lhs, const _Tp1& __rhs) const 1362 { return __lhs.owner_before(__rhs); } 1363 1364 bool 1365 operator()(const _Tp1& __lhs, const _Tp& __rhs) const 1366 { return __lhs.owner_before(__rhs); } 1367 }; 1368 1369 template<typename _Tp, _Lock_policy _Lp> 1370 struct owner_less<__shared_ptr<_Tp, _Lp>> 1371 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1372 { }; 1373 1374 template<typename _Tp, _Lock_policy _Lp> 1375 struct owner_less<__weak_ptr<_Tp, _Lp>> 1376 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1377 { }; 1378 1379 1380 template<typename _Tp, _Lock_policy _Lp> 1381 class __enable_shared_from_this 1382 { 1383 protected: 1384 constexpr __enable_shared_from_this() noexcept { } 1385 1386 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 1387 1388 __enable_shared_from_this& 1389 operator=(const __enable_shared_from_this&) noexcept 1390 { return *this; } 1391 1392 ~__enable_shared_from_this() { } 1393 1394 public: 1395 __shared_ptr<_Tp, _Lp> 1396 shared_from_this() 1397 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1398 1399 __shared_ptr<const _Tp, _Lp> 1400 shared_from_this() const 1401 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1402 1403 private: 1404 template<typename _Tp1> 1405 void 1406 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 1407 { _M_weak_this._M_assign(__p, __n); } 1408 1409 template<typename _Tp1> 1410 friend void 1411 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn, 1412 const __enable_shared_from_this* __pe, 1413 const _Tp1* __px) noexcept 1414 { 1415 if (__pe != 0) 1416 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); 1417 } 1418 1419 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1420 }; 1421 1422 1423 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1424 inline __shared_ptr<_Tp, _Lp> 1425 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1426 { 1427 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1428 std::forward<_Args>(__args)...); 1429 } 1430 1431 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1432 inline __shared_ptr<_Tp, _Lp> 1433 __make_shared(_Args&&... __args) 1434 { 1435 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1436 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1437 std::forward<_Args>(__args)...); 1438 } 1439 1440 /// std::hash specialization for __shared_ptr. 1441 template<typename _Tp, _Lock_policy _Lp> 1442 struct hash<__shared_ptr<_Tp, _Lp>> 1443 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 1444 { 1445 size_t 1446 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1447 { return std::hash<_Tp*>()(__s.get()); } 1448 }; 1449 1450 _GLIBCXX_END_NAMESPACE_VERSION 1451 } // namespace 1452 1453 #endif // _SHARED_PTR_BASE_H 1454
