1 // shared_ptr and weak_ptr implementation details -*- C++ -*- 2 3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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 /** 57 * @brief Exception possibly thrown by @c shared_ptr. 58 * @ingroup exceptions 59 */ 60 class bad_weak_ptr : public std::exception 61 { 62 public: 63 virtual char const* 64 what() const throw(); 65 66 virtual ~bad_weak_ptr() throw(); 67 }; 68 69 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 70 inline void 71 __throw_bad_weak_ptr() 72 { 73 #if __EXCEPTIONS 74 throw bad_weak_ptr(); 75 #else 76 __builtin_abort(); 77 #endif 78 } 79 80 using __gnu_cxx::_Lock_policy; 81 using __gnu_cxx::__default_lock_policy; 82 using __gnu_cxx::_S_single; 83 using __gnu_cxx::_S_mutex; 84 using __gnu_cxx::_S_atomic; 85 86 // Empty helper class except when the template argument is _S_mutex. 87 template<_Lock_policy _Lp> 88 class _Mutex_base 89 { 90 protected: 91 // The atomic policy uses fully-fenced builtins, single doesn't care. 92 enum { _S_need_barriers = 0 }; 93 }; 94 95 template<> 96 class _Mutex_base<_S_mutex> 97 : public __gnu_cxx::__mutex 98 { 99 protected: 100 // This policy is used when atomic builtins are not available. 101 // The replacement atomic operations might not have the necessary 102 // memory barriers. 103 enum { _S_need_barriers = 1 }; 104 }; 105 106 template<_Lock_policy _Lp = __default_lock_policy> 107 class _Sp_counted_base 108 : public _Mutex_base<_Lp> 109 { 110 public: 111 _Sp_counted_base() 112 : _M_use_count(1), _M_weak_count(1) { } 113 114 virtual 115 ~_Sp_counted_base() // nothrow 116 { } 117 118 // Called when _M_use_count drops to zero, to release the resources 119 // managed by *this. 120 virtual void 121 _M_dispose() = 0; // nothrow 122 123 // Called when _M_weak_count drops to zero. 124 virtual void 125 _M_destroy() // nothrow 126 { delete this; } 127 128 virtual void* 129 _M_get_deleter(const std::type_info&) = 0; 130 131 void 132 _M_add_ref_copy() 133 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 134 135 void 136 _M_add_ref_lock(); 137 138 void 139 _M_release() // nothrow 140 { 141 // Be race-detector-friendly. For more info see bits/c++config. 142 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 143 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 144 { 145 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 146 _M_dispose(); 147 // There must be a memory barrier between dispose() and destroy() 148 // to ensure that the effects of dispose() are observed in the 149 // thread that runs destroy(). 150 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 151 if (_Mutex_base<_Lp>::_S_need_barriers) 152 { 153 _GLIBCXX_READ_MEM_BARRIER; 154 _GLIBCXX_WRITE_MEM_BARRIER; 155 } 156 157 // Be race-detector-friendly. For more info see bits/c++config. 158 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 159 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 160 -1) == 1) 161 { 162 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 163 _M_destroy(); 164 } 165 } 166 } 167 168 void 169 _M_weak_add_ref() // nothrow 170 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 171 172 void 173 _M_weak_release() // nothrow 174 { 175 // Be race-detector-friendly. For more info see bits/c++config. 176 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 177 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 178 { 179 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 180 if (_Mutex_base<_Lp>::_S_need_barriers) 181 { 182 // See _M_release(), 183 // destroy() must observe results of dispose() 184 _GLIBCXX_READ_MEM_BARRIER; 185 _GLIBCXX_WRITE_MEM_BARRIER; 186 } 187 _M_destroy(); 188 } 189 } 190 191 long 192 _M_get_use_count() const // nothrow 193 { 194 // No memory barrier is used here so there is no synchronization 195 // with other threads. 196 return const_cast<const volatile _Atomic_word&>(_M_use_count); 197 } 198 199 private: 200 _Sp_counted_base(_Sp_counted_base const&); 201 _Sp_counted_base& operator=(_Sp_counted_base const&); 202 203 _Atomic_word _M_use_count; // #shared 204 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 205 }; 206 207 template<> 208 inline void 209 _Sp_counted_base<_S_single>:: 210 _M_add_ref_lock() 211 { 212 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 213 { 214 _M_use_count = 0; 215 __throw_bad_weak_ptr(); 216 } 217 } 218 219 template<> 220 inline void 221 _Sp_counted_base<_S_mutex>:: 222 _M_add_ref_lock() 223 { 224 __gnu_cxx::__scoped_lock sentry(*this); 225 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 226 { 227 _M_use_count = 0; 228 __throw_bad_weak_ptr(); 229 } 230 } 231 232 template<> 233 inline void 234 _Sp_counted_base<_S_atomic>:: 235 _M_add_ref_lock() 236 { 237 // Perform lock-free add-if-not-zero operation. 238 _Atomic_word __count; 239 do 240 { 241 __count = _M_use_count; 242 if (__count == 0) 243 __throw_bad_weak_ptr(); 244 245 // Replace the current counter value with the old value + 1, as 246 // long as it's not changed meanwhile. 247 } 248 while (!__sync_bool_compare_and_swap(&_M_use_count, __count, 249 __count + 1)); 250 } 251 252 253 // Forward declarations. 254 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 255 class __shared_ptr; 256 257 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 258 class __weak_ptr; 259 260 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 261 class __enable_shared_from_this; 262 263 template<typename _Tp> 264 class shared_ptr; 265 266 template<typename _Tp> 267 class weak_ptr; 268 269 template<typename _Tp> 270 struct owner_less; 271 272 template<typename _Tp> 273 class enable_shared_from_this; 274 275 template<_Lock_policy _Lp = __default_lock_policy> 276 class __weak_count; 277 278 template<_Lock_policy _Lp = __default_lock_policy> 279 class __shared_count; 280 281 282 // Counted ptr with no deleter or allocator support 283 template<typename _Ptr, _Lock_policy _Lp> 284 class _Sp_counted_ptr : public _Sp_counted_base<_Lp> 285 { 286 public: 287 explicit 288 _Sp_counted_ptr(_Ptr __p) 289 : _M_ptr(__p) { } 290 291 virtual void 292 _M_dispose() // nothrow 293 { delete _M_ptr; } 294 295 virtual void 296 _M_destroy() // nothrow 297 { delete this; } 298 299 virtual void* 300 _M_get_deleter(const std::type_info&) 301 { return 0; } 302 303 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 304 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 305 306 protected: 307 _Ptr _M_ptr; // copy constructor must not throw 308 }; 309 310 template<> 311 inline void 312 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() { } 313 314 template<> 315 inline void 316 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() { } 317 318 template<> 319 inline void 320 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() { } 321 322 // Support for custom deleter and/or allocator 323 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 324 class _Sp_counted_deleter : public _Sp_counted_base<_Lp> 325 { 326 typedef typename _Alloc::template 327 rebind<_Sp_counted_deleter>::other _My_alloc_type; 328 329 // Helper class that stores the Deleter and also acts as an allocator. 330 // Used to dispose of the owned pointer and the internal refcount 331 // Requires that copies of _Alloc can free each other's memory. 332 struct _My_Deleter 333 : public _My_alloc_type // copy constructor must not throw 334 { 335 _Deleter _M_del; // copy constructor must not throw 336 _My_Deleter(_Deleter __d, const _Alloc& __a) 337 : _My_alloc_type(__a), _M_del(__d) { } 338 }; 339 340 public: 341 // __d(__p) must not throw. 342 _Sp_counted_deleter(_Ptr __p, _Deleter __d) 343 : _M_ptr(__p), _M_del(__d, _Alloc()) { } 344 345 // __d(__p) must not throw. 346 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) 347 : _M_ptr(__p), _M_del(__d, __a) { } 348 349 virtual void 350 _M_dispose() // nothrow 351 { _M_del._M_del(_M_ptr); } 352 353 virtual void 354 _M_destroy() // nothrow 355 { 356 _My_alloc_type __a(_M_del); 357 this->~_Sp_counted_deleter(); 358 __a.deallocate(this, 1); 359 } 360 361 virtual void* 362 _M_get_deleter(const std::type_info& __ti) 363 { 364 #ifdef __GXX_RTTI 365 return __ti == typeid(_Deleter) ? &_M_del._M_del : 0; 366 #else 367 return 0; 368 #endif 369 } 370 371 protected: 372 _Ptr _M_ptr; // copy constructor must not throw 373 _My_Deleter _M_del; // copy constructor must not throw 374 }; 375 376 // helpers for make_shared / allocate_shared 377 378 template<typename _Tp> 379 struct _Sp_destroy_inplace 380 { 381 void operator()(_Tp* __p) const { if (__p) __p->~_Tp(); } 382 }; 383 384 struct _Sp_make_shared_tag { }; 385 386 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 387 class _Sp_counted_ptr_inplace 388 : public _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp> 389 { 390 typedef _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp> 391 _Base_type; 392 393 public: 394 explicit 395 _Sp_counted_ptr_inplace(_Alloc __a) 396 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a) 397 , _M_storage() 398 { 399 void* __p = &_M_storage; 400 ::new (__p) _Tp(); // might throw 401 _Base_type::_M_ptr = static_cast<_Tp*>(__p); 402 } 403 404 template<typename... _Args> 405 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 406 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a) 407 , _M_storage() 408 { 409 void* __p = &_M_storage; 410 ::new (__p) _Tp(std::forward<_Args>(__args)...); // might throw 411 _Base_type::_M_ptr = static_cast<_Tp*>(__p); 412 } 413 414 // Override because the allocator needs to know the dynamic type 415 virtual void 416 _M_destroy() // nothrow 417 { 418 typedef typename _Alloc::template 419 rebind<_Sp_counted_ptr_inplace>::other _My_alloc_type; 420 _My_alloc_type __a(_Base_type::_M_del); 421 this->~_Sp_counted_ptr_inplace(); 422 __a.deallocate(this, 1); 423 } 424 425 // Sneaky trick so __shared_ptr can get the managed pointer 426 virtual void* 427 _M_get_deleter(const std::type_info& __ti) 428 { 429 #ifdef __GXX_RTTI 430 return __ti == typeid(_Sp_make_shared_tag) 431 ? static_cast<void*>(&_M_storage) 432 : _Base_type::_M_get_deleter(__ti); 433 #else 434 return 0; 435 #endif 436 } 437 438 private: 439 typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type 440 _M_storage; 441 }; 442 443 template<_Lock_policy _Lp> 444 class __shared_count 445 { 446 public: 447 constexpr __shared_count() : _M_pi(0) // nothrow 448 { } 449 450 template<typename _Ptr> 451 explicit 452 __shared_count(_Ptr __p) : _M_pi(0) 453 { 454 __try 455 { 456 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 457 } 458 __catch(...) 459 { 460 delete __p; 461 __throw_exception_again; 462 } 463 } 464 465 template<typename _Ptr, typename _Deleter> 466 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0) 467 { 468 // The allocator's value_type doesn't matter, will rebind it anyway. 469 typedef std::allocator<int> _Alloc; 470 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 471 typedef std::allocator<_Sp_cd_type> _Alloc2; 472 _Alloc2 __a2; 473 __try 474 { 475 _M_pi = __a2.allocate(1); 476 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d); 477 } 478 __catch(...) 479 { 480 __d(__p); // Call _Deleter on __p. 481 if (_M_pi) 482 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1); 483 __throw_exception_again; 484 } 485 } 486 487 template<typename _Ptr, typename _Deleter, typename _Alloc> 488 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 489 { 490 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 491 typedef typename _Alloc::template rebind<_Sp_cd_type>::other _Alloc2; 492 _Alloc2 __a2(__a); 493 __try 494 { 495 _M_pi = __a2.allocate(1); 496 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d, __a); 497 } 498 __catch(...) 499 { 500 __d(__p); // Call _Deleter on __p. 501 if (_M_pi) 502 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1); 503 __throw_exception_again; 504 } 505 } 506 507 template<typename _Tp, typename _Alloc, typename... _Args> 508 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 509 _Args&&... __args) 510 : _M_pi(0) 511 { 512 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 513 typedef typename _Alloc::template rebind<_Sp_cp_type>::other _Alloc2; 514 _Alloc2 __a2(__a); 515 __try 516 { 517 _M_pi = __a2.allocate(1); 518 ::new(static_cast<void*>(_M_pi)) _Sp_cp_type(__a, 519 std::forward<_Args>(__args)...); 520 } 521 __catch(...) 522 { 523 if (_M_pi) 524 __a2.deallocate(static_cast<_Sp_cp_type*>(_M_pi), 1); 525 __throw_exception_again; 526 } 527 } 528 529 #if _GLIBCXX_USE_DEPRECATED 530 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 531 template<typename _Tp> 532 explicit 533 __shared_count(std::auto_ptr<_Tp>&& __r) 534 : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get())) 535 { __r.release(); } 536 #endif 537 538 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 539 template<typename _Tp, typename _Del> 540 explicit 541 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) 542 : _M_pi(_S_create_from_up(std::move(__r))) 543 { __r.release(); } 544 545 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 546 explicit __shared_count(const __weak_count<_Lp>& __r); 547 548 ~__shared_count() // nothrow 549 { 550 if (_M_pi != 0) 551 _M_pi->_M_release(); 552 } 553 554 __shared_count(const __shared_count& __r) 555 : _M_pi(__r._M_pi) // nothrow 556 { 557 if (_M_pi != 0) 558 _M_pi->_M_add_ref_copy(); 559 } 560 561 __shared_count& 562 operator=(const __shared_count& __r) // nothrow 563 { 564 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 565 if (__tmp != _M_pi) 566 { 567 if (__tmp != 0) 568 __tmp->_M_add_ref_copy(); 569 if (_M_pi != 0) 570 _M_pi->_M_release(); 571 _M_pi = __tmp; 572 } 573 return *this; 574 } 575 576 void 577 _M_swap(__shared_count& __r) // nothrow 578 { 579 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 580 __r._M_pi = _M_pi; 581 _M_pi = __tmp; 582 } 583 584 long 585 _M_get_use_count() const // nothrow 586 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 587 588 bool 589 _M_unique() const // nothrow 590 { return this->_M_get_use_count() == 1; } 591 592 void* 593 _M_get_deleter(const std::type_info& __ti) const 594 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } 595 596 bool 597 _M_less(const __shared_count& __rhs) const 598 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 599 600 bool 601 _M_less(const __weak_count<_Lp>& __rhs) const 602 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 603 604 // Friend function injected into enclosing namespace and found by ADL 605 friend inline bool 606 operator==(const __shared_count& __a, const __shared_count& __b) 607 { return __a._M_pi == __b._M_pi; } 608 609 private: 610 friend class __weak_count<_Lp>; 611 612 template<typename _Tp, typename _Del> 613 static _Sp_counted_base<_Lp>* 614 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 615 typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0) 616 { 617 return new _Sp_counted_deleter<_Tp*, _Del, std::allocator<_Tp>, 618 _Lp>(__r.get(), __r.get_deleter()); 619 } 620 621 template<typename _Tp, typename _Del> 622 static _Sp_counted_base<_Lp>* 623 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 624 typename std::enable_if<std::is_reference<_Del>::value>::type* = 0) 625 { 626 typedef typename std::remove_reference<_Del>::type _Del1; 627 typedef std::reference_wrapper<_Del1> _Del2; 628 return new _Sp_counted_deleter<_Tp*, _Del2, std::allocator<_Tp>, 629 _Lp>(__r.get(), std::ref(__r.get_deleter())); 630 } 631 632 _Sp_counted_base<_Lp>* _M_pi; 633 }; 634 635 636 template<_Lock_policy _Lp> 637 class __weak_count 638 { 639 public: 640 constexpr __weak_count() : _M_pi(0) // nothrow 641 { } 642 643 __weak_count(const __shared_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow 644 { 645 if (_M_pi != 0) 646 _M_pi->_M_weak_add_ref(); 647 } 648 649 __weak_count(const __weak_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow 650 { 651 if (_M_pi != 0) 652 _M_pi->_M_weak_add_ref(); 653 } 654 655 ~__weak_count() // nothrow 656 { 657 if (_M_pi != 0) 658 _M_pi->_M_weak_release(); 659 } 660 661 __weak_count<_Lp>& 662 operator=(const __shared_count<_Lp>& __r) // nothrow 663 { 664 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 665 if (__tmp != 0) 666 __tmp->_M_weak_add_ref(); 667 if (_M_pi != 0) 668 _M_pi->_M_weak_release(); 669 _M_pi = __tmp; 670 return *this; 671 } 672 673 __weak_count<_Lp>& 674 operator=(const __weak_count<_Lp>& __r) // nothrow 675 { 676 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 677 if (__tmp != 0) 678 __tmp->_M_weak_add_ref(); 679 if (_M_pi != 0) 680 _M_pi->_M_weak_release(); 681 _M_pi = __tmp; 682 return *this; 683 } 684 685 void 686 _M_swap(__weak_count<_Lp>& __r) // nothrow 687 { 688 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 689 __r._M_pi = _M_pi; 690 _M_pi = __tmp; 691 } 692 693 long 694 _M_get_use_count() const // nothrow 695 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 696 697 bool 698 _M_less(const __weak_count& __rhs) const 699 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 700 701 bool 702 _M_less(const __shared_count<_Lp>& __rhs) const 703 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 704 705 // Friend function injected into enclosing namespace and found by ADL 706 friend inline bool 707 operator==(const __weak_count& __a, const __weak_count& __b) 708 { return __a._M_pi == __b._M_pi; } 709 710 private: 711 friend class __shared_count<_Lp>; 712 713 _Sp_counted_base<_Lp>* _M_pi; 714 }; 715 716 // Now that __weak_count is defined we can define this constructor: 717 template<_Lock_policy _Lp> 718 inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r) 719 : _M_pi(__r._M_pi) 720 { 721 if (_M_pi != 0) 722 _M_pi->_M_add_ref_lock(); 723 else 724 __throw_bad_weak_ptr(); 725 } 726 727 728 // Support for enable_shared_from_this. 729 730 // Friend of __enable_shared_from_this. 731 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2> 732 void 733 __enable_shared_from_this_helper(const __shared_count<_Lp>&, 734 const __enable_shared_from_this<_Tp1, 735 _Lp>*, const _Tp2*); 736 737 // Friend of enable_shared_from_this. 738 template<typename _Tp1, typename _Tp2> 739 void 740 __enable_shared_from_this_helper(const __shared_count<>&, 741 const enable_shared_from_this<_Tp1>*, 742 const _Tp2*); 743 744 template<_Lock_policy _Lp> 745 inline void 746 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) 747 { } 748 749 750 template<typename _Tp, _Lock_policy _Lp> 751 class __shared_ptr 752 { 753 public: 754 typedef _Tp element_type; 755 756 constexpr __shared_ptr() 757 : _M_ptr(0), _M_refcount() // never throws 758 { } 759 760 template<typename _Tp1> 761 explicit __shared_ptr(_Tp1* __p) 762 : _M_ptr(__p), _M_refcount(__p) 763 { 764 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 765 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 766 __enable_shared_from_this_helper(_M_refcount, __p, __p); 767 } 768 769 template<typename _Tp1, typename _Deleter> 770 __shared_ptr(_Tp1* __p, _Deleter __d) 771 : _M_ptr(__p), _M_refcount(__p, __d) 772 { 773 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 774 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 775 __enable_shared_from_this_helper(_M_refcount, __p, __p); 776 } 777 778 template<typename _Tp1, typename _Deleter, typename _Alloc> 779 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 780 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a)) 781 { 782 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 783 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 784 __enable_shared_from_this_helper(_M_refcount, __p, __p); 785 } 786 787 template<typename _Deleter> 788 __shared_ptr(nullptr_t __p, _Deleter __d) 789 : _M_ptr(0), _M_refcount(__p, __d) 790 { } 791 792 template<typename _Deleter, typename _Alloc> 793 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 794 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) 795 { } 796 797 template<typename _Tp1> 798 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) 799 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 800 { } 801 802 __shared_ptr(const __shared_ptr&) = default; // never throws 803 __shared_ptr& operator=(const __shared_ptr&) = default; // never throws 804 805 template<typename _Tp1, typename = typename 806 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 807 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) 808 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 809 { } 810 811 __shared_ptr(__shared_ptr&& __r) 812 : _M_ptr(__r._M_ptr), _M_refcount() // never throws 813 { 814 _M_refcount._M_swap(__r._M_refcount); 815 __r._M_ptr = 0; 816 } 817 818 template<typename _Tp1, typename = typename 819 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 820 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) 821 : _M_ptr(__r._M_ptr), _M_refcount() // never throws 822 { 823 _M_refcount._M_swap(__r._M_refcount); 824 __r._M_ptr = 0; 825 } 826 827 template<typename _Tp1> 828 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 829 : _M_refcount(__r._M_refcount) // may throw 830 { 831 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 832 833 // It is now safe to copy __r._M_ptr, as 834 // _M_refcount(__r._M_refcount) did not throw. 835 _M_ptr = __r._M_ptr; 836 } 837 838 // If an exception is thrown this constructor has no effect. 839 template<typename _Tp1, typename _Del> 840 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) 841 : _M_ptr(__r.get()), _M_refcount() 842 { 843 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 844 _Tp1* __tmp = __r.get(); 845 _M_refcount = __shared_count<_Lp>(std::move(__r)); 846 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); 847 } 848 849 #if _GLIBCXX_USE_DEPRECATED 850 // Postcondition: use_count() == 1 and __r.get() == 0 851 template<typename _Tp1> 852 __shared_ptr(std::auto_ptr<_Tp1>&& __r) 853 : _M_ptr(__r.get()), _M_refcount() 854 { 855 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 856 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 857 _Tp1* __tmp = __r.get(); 858 _M_refcount = __shared_count<_Lp>(std::move(__r)); 859 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); 860 } 861 #endif 862 863 /* TODO: use delegating constructor */ 864 constexpr __shared_ptr(nullptr_t) 865 : _M_ptr(0), _M_refcount() // never throws 866 { } 867 868 template<typename _Tp1> 869 __shared_ptr& 870 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws 871 { 872 _M_ptr = __r._M_ptr; 873 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 874 return *this; 875 } 876 877 #if _GLIBCXX_USE_DEPRECATED 878 template<typename _Tp1> 879 __shared_ptr& 880 operator=(std::auto_ptr<_Tp1>&& __r) 881 { 882 __shared_ptr(std::move(__r)).swap(*this); 883 return *this; 884 } 885 #endif 886 887 __shared_ptr& 888 operator=(__shared_ptr&& __r) 889 { 890 __shared_ptr(std::move(__r)).swap(*this); 891 return *this; 892 } 893 894 template<class _Tp1> 895 __shared_ptr& 896 operator=(__shared_ptr<_Tp1, _Lp>&& __r) 897 { 898 __shared_ptr(std::move(__r)).swap(*this); 899 return *this; 900 } 901 902 template<typename _Tp1, typename _Del> 903 __shared_ptr& 904 operator=(std::unique_ptr<_Tp1, _Del>&& __r) 905 { 906 __shared_ptr(std::move(__r)).swap(*this); 907 return *this; 908 } 909 910 void 911 reset() // never throws 912 { __shared_ptr().swap(*this); } 913 914 template<typename _Tp1> 915 void 916 reset(_Tp1* __p) // _Tp1 must be complete. 917 { 918 // Catch self-reset errors. 919 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); 920 __shared_ptr(__p).swap(*this); 921 } 922 923 template<typename _Tp1, typename _Deleter> 924 void 925 reset(_Tp1* __p, _Deleter __d) 926 { __shared_ptr(__p, __d).swap(*this); } 927 928 template<typename _Tp1, typename _Deleter, typename _Alloc> 929 void 930 reset(_Tp1* __p, _Deleter __d, _Alloc __a) 931 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); } 932 933 // Allow class instantiation when _Tp is [cv-qual] void. 934 typename std::add_lvalue_reference<_Tp>::type 935 operator*() const // never throws 936 { 937 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 938 return *_M_ptr; 939 } 940 941 _Tp* 942 operator->() const // never throws 943 { 944 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 945 return _M_ptr; 946 } 947 948 _Tp* 949 get() const // never throws 950 { return _M_ptr; } 951 952 explicit operator bool() const // never throws 953 { return _M_ptr == 0 ? false : true; } 954 955 bool 956 unique() const // never throws 957 { return _M_refcount._M_unique(); } 958 959 long 960 use_count() const // never throws 961 { return _M_refcount._M_get_use_count(); } 962 963 void 964 swap(__shared_ptr<_Tp, _Lp>& __other) // never throws 965 { 966 std::swap(_M_ptr, __other._M_ptr); 967 _M_refcount._M_swap(__other._M_refcount); 968 } 969 970 template<typename _Tp1> 971 bool 972 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const 973 { return _M_refcount._M_less(__rhs._M_refcount); } 974 975 template<typename _Tp1> 976 bool 977 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const 978 { return _M_refcount._M_less(__rhs._M_refcount); } 979 980 #ifdef __GXX_RTTI 981 protected: 982 // This constructor is non-standard, it is used by allocate_shared. 983 template<typename _Alloc, typename... _Args> 984 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 985 _Args&&... __args) 986 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 987 std::forward<_Args>(__args)...) 988 { 989 // _M_ptr needs to point to the newly constructed object. 990 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 991 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 992 _M_ptr = static_cast<_Tp*>(__p); 993 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 994 } 995 #else 996 template<typename _Alloc> 997 struct _Deleter 998 { 999 void operator()(_Tp* __ptr) 1000 { 1001 _M_alloc.destroy(__ptr); 1002 _M_alloc.deallocate(__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 _M_ptr = __del._M_alloc.allocate(1); 1015 __try 1016 { 1017 __del._M_alloc.construct(_M_ptr, std::forward<_Args>(__args)...); 1018 } 1019 __catch(...) 1020 { 1021 __del._M_alloc.deallocate(_M_ptr, 1); 1022 __throw_exception_again; 1023 } 1024 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc); 1025 _M_refcount._M_swap(__count); 1026 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 1027 } 1028 #endif 1029 1030 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1031 typename... _Args> 1032 friend __shared_ptr<_Tp1, _Lp1> 1033 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1034 1035 private: 1036 void* 1037 _M_get_deleter(const std::type_info& __ti) const 1038 { return _M_refcount._M_get_deleter(__ti); } 1039 1040 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1041 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1042 1043 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1044 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&); 1045 1046 _Tp* _M_ptr; // Contained pointer. 1047 __shared_count<_Lp> _M_refcount; // Reference counter. 1048 }; 1049 1050 1051 // 20.8.13.2.7 shared_ptr comparisons 1052 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1053 inline bool 1054 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1055 const __shared_ptr<_Tp2, _Lp>& __b) 1056 { return __a.get() == __b.get(); } 1057 1058 template<typename _Tp, _Lock_policy _Lp> 1059 inline bool 1060 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) 1061 { return __a.get() == nullptr; } 1062 1063 template<typename _Tp, _Lock_policy _Lp> 1064 inline bool 1065 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b) 1066 { return nullptr == __b.get(); } 1067 1068 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1069 inline bool 1070 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1071 const __shared_ptr<_Tp2, _Lp>& __b) 1072 { return __a.get() != __b.get(); } 1073 1074 template<typename _Tp, _Lock_policy _Lp> 1075 inline bool 1076 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) 1077 { return __a.get() != nullptr; } 1078 1079 template<typename _Tp, _Lock_policy _Lp> 1080 inline bool 1081 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b) 1082 { return nullptr != __b.get(); } 1083 1084 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1085 inline bool 1086 operator<(const __shared_ptr<_Tp1, _Lp>& __a, 1087 const __shared_ptr<_Tp2, _Lp>& __b) 1088 { return __a.get() < __b.get(); } 1089 1090 template<typename _Sp> 1091 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1092 { 1093 bool 1094 operator()(const _Sp& __lhs, const _Sp& __rhs) const 1095 { 1096 typedef typename _Sp::element_type element_type; 1097 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1098 } 1099 }; 1100 1101 template<typename _Tp, _Lock_policy _Lp> 1102 struct less<__shared_ptr<_Tp, _Lp>> 1103 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1104 { }; 1105 1106 // 2.2.3.8 shared_ptr specialized algorithms. 1107 template<typename _Tp, _Lock_policy _Lp> 1108 inline void 1109 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) 1110 { __a.swap(__b); } 1111 1112 // 2.2.3.9 shared_ptr casts 1113 1114 // The seemingly equivalent code: 1115 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1116 // will eventually result in undefined behaviour, attempting to 1117 // delete the same object twice. 1118 /// static_pointer_cast 1119 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1120 inline __shared_ptr<_Tp, _Lp> 1121 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) 1122 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); } 1123 1124 // The seemingly equivalent code: 1125 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1126 // will eventually result in undefined behaviour, attempting to 1127 // delete the same object twice. 1128 /// const_pointer_cast 1129 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1130 inline __shared_ptr<_Tp, _Lp> 1131 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) 1132 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); } 1133 1134 // The seemingly equivalent code: 1135 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1136 // will eventually result in undefined behaviour, attempting to 1137 // delete the same object twice. 1138 /// dynamic_pointer_cast 1139 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1140 inline __shared_ptr<_Tp, _Lp> 1141 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) 1142 { 1143 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) 1144 return __shared_ptr<_Tp, _Lp>(__r, __p); 1145 return __shared_ptr<_Tp, _Lp>(); 1146 } 1147 1148 1149 template<typename _Tp, _Lock_policy _Lp> 1150 class __weak_ptr 1151 { 1152 public: 1153 typedef _Tp element_type; 1154 1155 constexpr __weak_ptr() 1156 : _M_ptr(0), _M_refcount() // never throws 1157 { } 1158 1159 // Generated copy constructor, assignment, destructor are fine. 1160 1161 // The "obvious" converting constructor implementation: 1162 // 1163 // template<typename _Tp1> 1164 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1165 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1166 // { } 1167 // 1168 // has a serious problem. 1169 // 1170 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1171 // conversion may require access to *__r._M_ptr (virtual inheritance). 1172 // 1173 // It is not possible to avoid spurious access violations since 1174 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1175 template<typename _Tp1, typename = typename 1176 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1177 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1178 : _M_refcount(__r._M_refcount) // never throws 1179 { _M_ptr = __r.lock().get(); } 1180 1181 template<typename _Tp1, typename = typename 1182 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 1183 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) 1184 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1185 { } 1186 1187 template<typename _Tp1> 1188 __weak_ptr& 1189 operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws 1190 { 1191 _M_ptr = __r.lock().get(); 1192 _M_refcount = __r._M_refcount; 1193 return *this; 1194 } 1195 1196 template<typename _Tp1> 1197 __weak_ptr& 1198 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws 1199 { 1200 _M_ptr = __r._M_ptr; 1201 _M_refcount = __r._M_refcount; 1202 return *this; 1203 } 1204 1205 __shared_ptr<_Tp, _Lp> 1206 lock() const // never throws 1207 { 1208 #ifdef __GTHREADS 1209 // Optimization: avoid throw overhead. 1210 if (expired()) 1211 return __shared_ptr<element_type, _Lp>(); 1212 1213 __try 1214 { 1215 return __shared_ptr<element_type, _Lp>(*this); 1216 } 1217 __catch(const bad_weak_ptr&) 1218 { 1219 // Q: How can we get here? 1220 // A: Another thread may have invalidated r after the 1221 // use_count test above. 1222 return __shared_ptr<element_type, _Lp>(); 1223 } 1224 1225 #else 1226 // Optimization: avoid try/catch overhead when single threaded. 1227 return expired() ? __shared_ptr<element_type, _Lp>() 1228 : __shared_ptr<element_type, _Lp>(*this); 1229 1230 #endif 1231 } // XXX MT 1232 1233 long 1234 use_count() const // never throws 1235 { return _M_refcount._M_get_use_count(); } 1236 1237 bool 1238 expired() const // never throws 1239 { return _M_refcount._M_get_use_count() == 0; } 1240 1241 template<typename _Tp1> 1242 bool 1243 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const 1244 { return _M_refcount._M_less(__rhs._M_refcount); } 1245 1246 template<typename _Tp1> 1247 bool 1248 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const 1249 { return _M_refcount._M_less(__rhs._M_refcount); } 1250 1251 void 1252 reset() // never throws 1253 { __weak_ptr().swap(*this); } 1254 1255 void 1256 swap(__weak_ptr& __s) // never throws 1257 { 1258 std::swap(_M_ptr, __s._M_ptr); 1259 _M_refcount._M_swap(__s._M_refcount); 1260 } 1261 1262 private: 1263 // Used by __enable_shared_from_this. 1264 void 1265 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) 1266 { 1267 _M_ptr = __ptr; 1268 _M_refcount = __refcount; 1269 } 1270 1271 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1272 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1273 friend class __enable_shared_from_this<_Tp, _Lp>; 1274 friend class enable_shared_from_this<_Tp>; 1275 1276 _Tp* _M_ptr; // Contained pointer. 1277 __weak_count<_Lp> _M_refcount; // Reference counter. 1278 }; 1279 1280 // 20.8.13.3.7 weak_ptr specialized algorithms. 1281 template<typename _Tp, _Lock_policy _Lp> 1282 inline void 1283 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) 1284 { __a.swap(__b); } 1285 1286 template<typename _Tp, typename _Tp1> 1287 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1288 { 1289 bool 1290 operator()(const _Tp& __lhs, const _Tp& __rhs) const 1291 { return __lhs.owner_before(__rhs); } 1292 1293 bool 1294 operator()(const _Tp& __lhs, const _Tp1& __rhs) const 1295 { return __lhs.owner_before(__rhs); } 1296 1297 bool 1298 operator()(const _Tp1& __lhs, const _Tp& __rhs) const 1299 { return __lhs.owner_before(__rhs); } 1300 }; 1301 1302 template<typename _Tp, _Lock_policy _Lp> 1303 struct owner_less<__shared_ptr<_Tp, _Lp>> 1304 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1305 { }; 1306 1307 template<typename _Tp, _Lock_policy _Lp> 1308 struct owner_less<__weak_ptr<_Tp, _Lp>> 1309 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1310 { }; 1311 1312 1313 template<typename _Tp, _Lock_policy _Lp> 1314 class __enable_shared_from_this 1315 { 1316 protected: 1317 constexpr __enable_shared_from_this() { } 1318 1319 __enable_shared_from_this(const __enable_shared_from_this&) { } 1320 1321 __enable_shared_from_this& 1322 operator=(const __enable_shared_from_this&) 1323 { return *this; } 1324 1325 ~__enable_shared_from_this() { } 1326 1327 public: 1328 __shared_ptr<_Tp, _Lp> 1329 shared_from_this() 1330 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1331 1332 __shared_ptr<const _Tp, _Lp> 1333 shared_from_this() const 1334 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1335 1336 private: 1337 template<typename _Tp1> 1338 void 1339 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const 1340 { _M_weak_this._M_assign(__p, __n); } 1341 1342 template<typename _Tp1> 1343 friend void 1344 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn, 1345 const __enable_shared_from_this* __pe, 1346 const _Tp1* __px) 1347 { 1348 if (__pe != 0) 1349 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); 1350 } 1351 1352 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1353 }; 1354 1355 1356 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1357 inline __shared_ptr<_Tp, _Lp> 1358 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1359 { 1360 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1361 std::forward<_Args>(__args)...); 1362 } 1363 1364 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1365 inline __shared_ptr<_Tp, _Lp> 1366 __make_shared(_Args&&... __args) 1367 { 1368 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1369 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1370 std::forward<_Args>(__args)...); 1371 } 1372 1373 /// std::hash specialization for __shared_ptr. 1374 template<typename _Tp, _Lock_policy _Lp> 1375 struct hash<__shared_ptr<_Tp, _Lp>> 1376 : public std::unary_function<__shared_ptr<_Tp, _Lp>, size_t> 1377 { 1378 size_t 1379 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1380 { return std::hash<_Tp*>()(__s.get()); } 1381 }; 1382 1383 _GLIBCXX_END_NAMESPACE_VERSION 1384 } // namespace 1385 1386 #endif // _SHARED_PTR_BASE_H 1387
