libstdc++
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00001 // shared_ptr and weak_ptr implementation details -*- C++ -*- 00002 00003 // Copyright (C) 2007-2013 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 // GCC Note: Based on files from version 1.32.0 of the Boost library. 00026 00027 // shared_count.hpp 00028 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. 00029 00030 // shared_ptr.hpp 00031 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes. 00032 // Copyright (C) 2001, 2002, 2003 Peter Dimov 00033 00034 // weak_ptr.hpp 00035 // Copyright (C) 2001, 2002, 2003 Peter Dimov 00036 00037 // enable_shared_from_this.hpp 00038 // Copyright (C) 2002 Peter Dimov 00039 00040 // Distributed under the Boost Software License, Version 1.0. (See 00041 // accompanying file LICENSE_1_0.txt or copy at 00042 // http://www.boost.org/LICENSE_1_0.txt) 00043 00044 /** @file bits/shared_ptr_base.h 00045 * This is an internal header file, included by other library headers. 00046 * Do not attempt to use it directly. @headername{memory} 00047 */ 00048 00049 #ifndef _SHARED_PTR_BASE_H 00050 #define _SHARED_PTR_BASE_H 1 00051 00052 namespace std _GLIBCXX_VISIBILITY(default) 00053 { 00054 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00055 00056 #if _GLIBCXX_USE_DEPRECATED 00057 template<typename> class auto_ptr; 00058 #endif 00059 00060 /** 00061 * @brief Exception possibly thrown by @c shared_ptr. 00062 * @ingroup exceptions 00063 */ 00064 class bad_weak_ptr : public std::exception 00065 { 00066 public: 00067 virtual char const* 00068 what() const noexcept; 00069 00070 virtual ~bad_weak_ptr() noexcept; 00071 }; 00072 00073 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 00074 inline void 00075 __throw_bad_weak_ptr() 00076 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } 00077 00078 using __gnu_cxx::_Lock_policy; 00079 using __gnu_cxx::__default_lock_policy; 00080 using __gnu_cxx::_S_single; 00081 using __gnu_cxx::_S_mutex; 00082 using __gnu_cxx::_S_atomic; 00083 00084 // Empty helper class except when the template argument is _S_mutex. 00085 template<_Lock_policy _Lp> 00086 class _Mutex_base 00087 { 00088 protected: 00089 // The atomic policy uses fully-fenced builtins, single doesn't care. 00090 enum { _S_need_barriers = 0 }; 00091 }; 00092 00093 template<> 00094 class _Mutex_base<_S_mutex> 00095 : public __gnu_cxx::__mutex 00096 { 00097 protected: 00098 // This policy is used when atomic builtins are not available. 00099 // The replacement atomic operations might not have the necessary 00100 // memory barriers. 00101 enum { _S_need_barriers = 1 }; 00102 }; 00103 00104 template<_Lock_policy _Lp = __default_lock_policy> 00105 class _Sp_counted_base 00106 : public _Mutex_base<_Lp> 00107 { 00108 public: 00109 _Sp_counted_base() noexcept 00110 : _M_use_count(1), _M_weak_count(1) { } 00111 00112 virtual 00113 ~_Sp_counted_base() noexcept 00114 { } 00115 00116 // Called when _M_use_count drops to zero, to release the resources 00117 // managed by *this. 00118 virtual void 00119 _M_dispose() noexcept = 0; 00120 00121 // Called when _M_weak_count drops to zero. 00122 virtual void 00123 _M_destroy() noexcept 00124 { delete this; } 00125 00126 virtual void* 00127 _M_get_deleter(const std::type_info&) = 0; 00128 00129 void 00130 _M_add_ref_copy() 00131 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 00132 00133 void 00134 _M_add_ref_lock(); 00135 00136 void 00137 _M_release() noexcept 00138 { 00139 // Be race-detector-friendly. For more info see bits/c++config. 00140 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 00141 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 00142 { 00143 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 00144 _M_dispose(); 00145 // There must be a memory barrier between dispose() and destroy() 00146 // to ensure that the effects of dispose() are observed in the 00147 // thread that runs destroy(). 00148 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 00149 if (_Mutex_base<_Lp>::_S_need_barriers) 00150 { 00151 _GLIBCXX_READ_MEM_BARRIER; 00152 _GLIBCXX_WRITE_MEM_BARRIER; 00153 } 00154 00155 // Be race-detector-friendly. For more info see bits/c++config. 00156 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 00157 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 00158 -1) == 1) 00159 { 00160 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 00161 _M_destroy(); 00162 } 00163 } 00164 } 00165 00166 void 00167 _M_weak_add_ref() noexcept 00168 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 00169 00170 void 00171 _M_weak_release() noexcept 00172 { 00173 // Be race-detector-friendly. For more info see bits/c++config. 00174 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 00175 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 00176 { 00177 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 00178 if (_Mutex_base<_Lp>::_S_need_barriers) 00179 { 00180 // See _M_release(), 00181 // destroy() must observe results of dispose() 00182 _GLIBCXX_READ_MEM_BARRIER; 00183 _GLIBCXX_WRITE_MEM_BARRIER; 00184 } 00185 _M_destroy(); 00186 } 00187 } 00188 00189 long 00190 _M_get_use_count() const noexcept 00191 { 00192 // No memory barrier is used here so there is no synchronization 00193 // with other threads. 00194 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); 00195 } 00196 00197 private: 00198 _Sp_counted_base(_Sp_counted_base const&) = delete; 00199 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; 00200 00201 _Atomic_word _M_use_count; // #shared 00202 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 00203 }; 00204 00205 template<> 00206 inline void 00207 _Sp_counted_base<_S_single>:: 00208 _M_add_ref_lock() 00209 { 00210 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 00211 { 00212 _M_use_count = 0; 00213 __throw_bad_weak_ptr(); 00214 } 00215 } 00216 00217 template<> 00218 inline void 00219 _Sp_counted_base<_S_mutex>:: 00220 _M_add_ref_lock() 00221 { 00222 __gnu_cxx::__scoped_lock sentry(*this); 00223 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 00224 { 00225 _M_use_count = 0; 00226 __throw_bad_weak_ptr(); 00227 } 00228 } 00229 00230 template<> 00231 inline void 00232 _Sp_counted_base<_S_atomic>:: 00233 _M_add_ref_lock() 00234 { 00235 // Perform lock-free add-if-not-zero operation. 00236 _Atomic_word __count = _M_use_count; 00237 do 00238 { 00239 if (__count == 0) 00240 __throw_bad_weak_ptr(); 00241 // Replace the current counter value with the old value + 1, as 00242 // long as it's not changed meanwhile. 00243 } 00244 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 00245 true, __ATOMIC_ACQ_REL, 00246 __ATOMIC_RELAXED)); 00247 } 00248 00249 00250 // Forward declarations. 00251 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 00252 class __shared_ptr; 00253 00254 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 00255 class __weak_ptr; 00256 00257 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 00258 class __enable_shared_from_this; 00259 00260 template<typename _Tp> 00261 class shared_ptr; 00262 00263 template<typename _Tp> 00264 class weak_ptr; 00265 00266 template<typename _Tp> 00267 struct owner_less; 00268 00269 template<typename _Tp> 00270 class enable_shared_from_this; 00271 00272 template<_Lock_policy _Lp = __default_lock_policy> 00273 class __weak_count; 00274 00275 template<_Lock_policy _Lp = __default_lock_policy> 00276 class __shared_count; 00277 00278 00279 // Counted ptr with no deleter or allocator support 00280 template<typename _Ptr, _Lock_policy _Lp> 00281 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> 00282 { 00283 public: 00284 explicit 00285 _Sp_counted_ptr(_Ptr __p) 00286 : _M_ptr(__p) { } 00287 00288 virtual void 00289 _M_dispose() noexcept 00290 { delete _M_ptr; } 00291 00292 virtual void 00293 _M_destroy() noexcept 00294 { delete this; } 00295 00296 virtual void* 00297 _M_get_deleter(const std::type_info&) 00298 { return 0; } 00299 00300 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 00301 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 00302 00303 protected: 00304 _Ptr _M_ptr; // copy constructor must not throw 00305 }; 00306 00307 template<> 00308 inline void 00309 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } 00310 00311 template<> 00312 inline void 00313 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } 00314 00315 template<> 00316 inline void 00317 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } 00318 00319 // Support for custom deleter and/or allocator 00320 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 00321 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> 00322 { 00323 // Helper class that stores the Deleter and also acts as an allocator. 00324 // Used to dispose of the owned pointer and the internal refcount 00325 // Requires that copies of _Alloc can free each other's memory. 00326 struct _My_Deleter 00327 : public _Alloc // copy constructor must not throw 00328 { 00329 _Deleter _M_del; // copy constructor must not throw 00330 _My_Deleter(_Deleter __d, const _Alloc& __a) 00331 : _Alloc(__a), _M_del(__d) { } 00332 }; 00333 00334 public: 00335 // __d(__p) must not throw. 00336 _Sp_counted_deleter(_Ptr __p, _Deleter __d) 00337 : _M_ptr(__p), _M_del(__d, _Alloc()) { } 00338 00339 // __d(__p) must not throw. 00340 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) 00341 : _M_ptr(__p), _M_del(__d, __a) { } 00342 00343 ~_Sp_counted_deleter() noexcept { } 00344 00345 virtual void 00346 _M_dispose() noexcept 00347 { _M_del._M_del(_M_ptr); } 00348 00349 virtual void 00350 _M_destroy() noexcept 00351 { 00352 typedef typename allocator_traits<_Alloc>::template 00353 rebind_traits<_Sp_counted_deleter> _Alloc_traits; 00354 typename _Alloc_traits::allocator_type __a(_M_del); 00355 _Alloc_traits::destroy(__a, this); 00356 _Alloc_traits::deallocate(__a, this, 1); 00357 } 00358 00359 virtual void* 00360 _M_get_deleter(const std::type_info& __ti) 00361 { 00362 #ifdef __GXX_RTTI 00363 return __ti == typeid(_Deleter) ? &_M_del._M_del : 0; 00364 #else 00365 return 0; 00366 #endif 00367 } 00368 00369 protected: 00370 _Ptr _M_ptr; // copy constructor must not throw 00371 _My_Deleter _M_del; // copy constructor must not throw 00372 }; 00373 00374 // helpers for make_shared / allocate_shared 00375 00376 struct _Sp_make_shared_tag { }; 00377 00378 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 00379 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> 00380 { 00381 // Helper class that stores the pointer and also acts as an allocator. 00382 // Used to dispose of the owned pointer and the internal refcount 00383 // Requires that copies of _Alloc can free each other's memory. 00384 struct _Impl 00385 : public _Alloc // copy constructor must not throw 00386 { 00387 _Impl(_Alloc __a) : _Alloc(__a), _M_ptr() { } 00388 _Tp* _M_ptr; 00389 }; 00390 00391 public: 00392 template<typename... _Args> 00393 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 00394 : _M_impl(__a), _M_storage() 00395 { 00396 _M_impl._M_ptr = static_cast<_Tp*>(static_cast<void*>(&_M_storage)); 00397 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00398 // 2070. allocate_shared should use allocator_traits<A>::construct 00399 allocator_traits<_Alloc>::construct(__a, _M_impl._M_ptr, 00400 std::forward<_Args>(__args)...); // might throw 00401 } 00402 00403 ~_Sp_counted_ptr_inplace() noexcept { } 00404 00405 virtual void 00406 _M_dispose() noexcept 00407 { allocator_traits<_Alloc>::destroy(_M_impl, _M_impl._M_ptr); } 00408 00409 // Override because the allocator needs to know the dynamic type 00410 virtual void 00411 _M_destroy() noexcept 00412 { 00413 typedef typename allocator_traits<_Alloc>::template 00414 rebind_traits<_Sp_counted_ptr_inplace> _Alloc_traits; 00415 typename _Alloc_traits::allocator_type __a(_M_impl); 00416 _Alloc_traits::destroy(__a, this); 00417 _Alloc_traits::deallocate(__a, this, 1); 00418 } 00419 00420 // Sneaky trick so __shared_ptr can get the managed pointer 00421 virtual void* 00422 _M_get_deleter(const std::type_info& __ti) noexcept 00423 { 00424 #ifdef __GXX_RTTI 00425 return __ti == typeid(_Sp_make_shared_tag) 00426 ? static_cast<void*>(&_M_storage) 00427 : 0; 00428 #else 00429 return 0; 00430 #endif 00431 } 00432 00433 private: 00434 _Impl _M_impl; 00435 typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type 00436 _M_storage; 00437 }; 00438 00439 template<_Lock_policy _Lp> 00440 class __shared_count 00441 { 00442 public: 00443 constexpr __shared_count() noexcept : _M_pi(0) 00444 { } 00445 00446 template<typename _Ptr> 00447 explicit 00448 __shared_count(_Ptr __p) : _M_pi(0) 00449 { 00450 __try 00451 { 00452 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 00453 } 00454 __catch(...) 00455 { 00456 delete __p; 00457 __throw_exception_again; 00458 } 00459 } 00460 00461 template<typename _Ptr, typename _Deleter> 00462 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0) 00463 { 00464 // The allocator's value_type doesn't matter, will rebind it anyway. 00465 typedef std::allocator<int> _Alloc; 00466 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 00467 typedef typename allocator_traits<_Alloc>::template 00468 rebind_traits<_Sp_cd_type> _Alloc_traits; 00469 typename _Alloc_traits::allocator_type __a; 00470 _Sp_cd_type* __mem = 0; 00471 __try 00472 { 00473 __mem = _Alloc_traits::allocate(__a, 1); 00474 _Alloc_traits::construct(__a, __mem, __p, std::move(__d)); 00475 _M_pi = __mem; 00476 } 00477 __catch(...) 00478 { 00479 __d(__p); // Call _Deleter on __p. 00480 if (__mem) 00481 _Alloc_traits::deallocate(__a, __mem, 1); 00482 __throw_exception_again; 00483 } 00484 } 00485 00486 template<typename _Ptr, typename _Deleter, typename _Alloc> 00487 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 00488 { 00489 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 00490 typedef typename allocator_traits<_Alloc>::template 00491 rebind_traits<_Sp_cd_type> _Alloc_traits; 00492 typename _Alloc_traits::allocator_type __a2(__a); 00493 _Sp_cd_type* __mem = 0; 00494 __try 00495 { 00496 __mem = _Alloc_traits::allocate(__a2, 1); 00497 _Alloc_traits::construct(__a2, __mem, 00498 __p, std::move(__d), std::move(__a)); 00499 _M_pi = __mem; 00500 } 00501 __catch(...) 00502 { 00503 __d(__p); // Call _Deleter on __p. 00504 if (__mem) 00505 _Alloc_traits::deallocate(__a2, __mem, 1); 00506 __throw_exception_again; 00507 } 00508 } 00509 00510 template<typename _Tp, typename _Alloc, typename... _Args> 00511 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 00512 _Args&&... __args) 00513 : _M_pi(0) 00514 { 00515 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 00516 typedef typename allocator_traits<_Alloc>::template 00517 rebind_traits<_Sp_cp_type> _Alloc_traits; 00518 typename _Alloc_traits::allocator_type __a2(__a); 00519 _Sp_cp_type* __mem = _Alloc_traits::allocate(__a2, 1); 00520 __try 00521 { 00522 _Alloc_traits::construct(__a2, __mem, std::move(__a), 00523 std::forward<_Args>(__args)...); 00524 _M_pi = __mem; 00525 } 00526 __catch(...) 00527 { 00528 _Alloc_traits::deallocate(__a2, __mem, 1); 00529 __throw_exception_again; 00530 } 00531 } 00532 00533 #if _GLIBCXX_USE_DEPRECATED 00534 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 00535 template<typename _Tp> 00536 explicit 00537 __shared_count(std::auto_ptr<_Tp>&& __r); 00538 #endif 00539 00540 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 00541 template<typename _Tp, typename _Del> 00542 explicit 00543 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) 00544 : _M_pi(_S_create_from_up(std::move(__r))) 00545 { __r.release(); } 00546 00547 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 00548 explicit __shared_count(const __weak_count<_Lp>& __r); 00549 00550 ~__shared_count() noexcept 00551 { 00552 if (_M_pi != 0) 00553 _M_pi->_M_release(); 00554 } 00555 00556 __shared_count(const __shared_count& __r) noexcept 00557 : _M_pi(__r._M_pi) 00558 { 00559 if (_M_pi != 0) 00560 _M_pi->_M_add_ref_copy(); 00561 } 00562 00563 __shared_count& 00564 operator=(const __shared_count& __r) noexcept 00565 { 00566 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 00567 if (__tmp != _M_pi) 00568 { 00569 if (__tmp != 0) 00570 __tmp->_M_add_ref_copy(); 00571 if (_M_pi != 0) 00572 _M_pi->_M_release(); 00573 _M_pi = __tmp; 00574 } 00575 return *this; 00576 } 00577 00578 void 00579 _M_swap(__shared_count& __r) noexcept 00580 { 00581 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 00582 __r._M_pi = _M_pi; 00583 _M_pi = __tmp; 00584 } 00585 00586 long 00587 _M_get_use_count() const noexcept 00588 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 00589 00590 bool 00591 _M_unique() const noexcept 00592 { return this->_M_get_use_count() == 1; } 00593 00594 void* 00595 _M_get_deleter(const std::type_info& __ti) const noexcept 00596 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } 00597 00598 bool 00599 _M_less(const __shared_count& __rhs) const noexcept 00600 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 00601 00602 bool 00603 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 00604 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 00605 00606 // Friend function injected into enclosing namespace and found by ADL 00607 friend inline bool 00608 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 00609 { return __a._M_pi == __b._M_pi; } 00610 00611 private: 00612 friend class __weak_count<_Lp>; 00613 00614 template<typename _Tp, typename _Del> 00615 static _Sp_counted_base<_Lp>* 00616 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 00617 typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0) 00618 { 00619 typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr; 00620 return new _Sp_counted_deleter<_Ptr, _Del, std::allocator<void>, 00621 _Lp>(__r.get(), __r.get_deleter()); 00622 } 00623 00624 template<typename _Tp, typename _Del> 00625 static _Sp_counted_base<_Lp>* 00626 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, 00627 typename std::enable_if<std::is_reference<_Del>::value>::type* = 0) 00628 { 00629 typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr; 00630 typedef typename std::remove_reference<_Del>::type _Del1; 00631 typedef std::reference_wrapper<_Del1> _Del2; 00632 return new _Sp_counted_deleter<_Ptr, _Del2, std::allocator<void>, 00633 _Lp>(__r.get(), std::ref(__r.get_deleter())); 00634 } 00635 00636 _Sp_counted_base<_Lp>* _M_pi; 00637 }; 00638 00639 00640 template<_Lock_policy _Lp> 00641 class __weak_count 00642 { 00643 public: 00644 constexpr __weak_count() noexcept : _M_pi(0) 00645 { } 00646 00647 __weak_count(const __shared_count<_Lp>& __r) noexcept 00648 : _M_pi(__r._M_pi) 00649 { 00650 if (_M_pi != 0) 00651 _M_pi->_M_weak_add_ref(); 00652 } 00653 00654 __weak_count(const __weak_count<_Lp>& __r) noexcept 00655 : _M_pi(__r._M_pi) 00656 { 00657 if (_M_pi != 0) 00658 _M_pi->_M_weak_add_ref(); 00659 } 00660 00661 ~__weak_count() noexcept 00662 { 00663 if (_M_pi != 0) 00664 _M_pi->_M_weak_release(); 00665 } 00666 00667 __weak_count<_Lp>& 00668 operator=(const __shared_count<_Lp>& __r) noexcept 00669 { 00670 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 00671 if (__tmp != 0) 00672 __tmp->_M_weak_add_ref(); 00673 if (_M_pi != 0) 00674 _M_pi->_M_weak_release(); 00675 _M_pi = __tmp; 00676 return *this; 00677 } 00678 00679 __weak_count<_Lp>& 00680 operator=(const __weak_count<_Lp>& __r) noexcept 00681 { 00682 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 00683 if (__tmp != 0) 00684 __tmp->_M_weak_add_ref(); 00685 if (_M_pi != 0) 00686 _M_pi->_M_weak_release(); 00687 _M_pi = __tmp; 00688 return *this; 00689 } 00690 00691 void 00692 _M_swap(__weak_count<_Lp>& __r) noexcept 00693 { 00694 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 00695 __r._M_pi = _M_pi; 00696 _M_pi = __tmp; 00697 } 00698 00699 long 00700 _M_get_use_count() const noexcept 00701 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 00702 00703 bool 00704 _M_less(const __weak_count& __rhs) const noexcept 00705 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 00706 00707 bool 00708 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 00709 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 00710 00711 // Friend function injected into enclosing namespace and found by ADL 00712 friend inline bool 00713 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 00714 { return __a._M_pi == __b._M_pi; } 00715 00716 private: 00717 friend class __shared_count<_Lp>; 00718 00719 _Sp_counted_base<_Lp>* _M_pi; 00720 }; 00721 00722 // Now that __weak_count is defined we can define this constructor: 00723 template<_Lock_policy _Lp> 00724 inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r) 00725 : _M_pi(__r._M_pi) 00726 { 00727 if (_M_pi != 0) 00728 _M_pi->_M_add_ref_lock(); 00729 else 00730 __throw_bad_weak_ptr(); 00731 } 00732 00733 00734 // Support for enable_shared_from_this. 00735 00736 // Friend of __enable_shared_from_this. 00737 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2> 00738 void 00739 __enable_shared_from_this_helper(const __shared_count<_Lp>&, 00740 const __enable_shared_from_this<_Tp1, 00741 _Lp>*, const _Tp2*) noexcept; 00742 00743 // Friend of enable_shared_from_this. 00744 template<typename _Tp1, typename _Tp2> 00745 void 00746 __enable_shared_from_this_helper(const __shared_count<>&, 00747 const enable_shared_from_this<_Tp1>*, 00748 const _Tp2*) noexcept; 00749 00750 template<_Lock_policy _Lp> 00751 inline void 00752 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept 00753 { } 00754 00755 00756 template<typename _Tp, _Lock_policy _Lp> 00757 class __shared_ptr 00758 { 00759 public: 00760 typedef _Tp element_type; 00761 00762 constexpr __shared_ptr() noexcept 00763 : _M_ptr(0), _M_refcount() 00764 { } 00765 00766 template<typename _Tp1> 00767 explicit __shared_ptr(_Tp1* __p) 00768 : _M_ptr(__p), _M_refcount(__p) 00769 { 00770 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 00771 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 00772 __enable_shared_from_this_helper(_M_refcount, __p, __p); 00773 } 00774 00775 template<typename _Tp1, typename _Deleter> 00776 __shared_ptr(_Tp1* __p, _Deleter __d) 00777 : _M_ptr(__p), _M_refcount(__p, __d) 00778 { 00779 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 00780 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 00781 __enable_shared_from_this_helper(_M_refcount, __p, __p); 00782 } 00783 00784 template<typename _Tp1, typename _Deleter, typename _Alloc> 00785 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 00786 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a)) 00787 { 00788 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 00789 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 00790 __enable_shared_from_this_helper(_M_refcount, __p, __p); 00791 } 00792 00793 template<typename _Deleter> 00794 __shared_ptr(nullptr_t __p, _Deleter __d) 00795 : _M_ptr(0), _M_refcount(__p, __d) 00796 { } 00797 00798 template<typename _Deleter, typename _Alloc> 00799 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 00800 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) 00801 { } 00802 00803 template<typename _Tp1> 00804 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) noexcept 00805 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 00806 { } 00807 00808 __shared_ptr(const __shared_ptr&) noexcept = default; 00809 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 00810 ~__shared_ptr() = default; 00811 00812 template<typename _Tp1, typename = typename 00813 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 00814 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 00815 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 00816 { } 00817 00818 __shared_ptr(__shared_ptr&& __r) noexcept 00819 : _M_ptr(__r._M_ptr), _M_refcount() 00820 { 00821 _M_refcount._M_swap(__r._M_refcount); 00822 __r._M_ptr = 0; 00823 } 00824 00825 template<typename _Tp1, typename = typename 00826 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 00827 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 00828 : _M_ptr(__r._M_ptr), _M_refcount() 00829 { 00830 _M_refcount._M_swap(__r._M_refcount); 00831 __r._M_ptr = 0; 00832 } 00833 00834 template<typename _Tp1> 00835 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 00836 : _M_refcount(__r._M_refcount) // may throw 00837 { 00838 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 00839 00840 // It is now safe to copy __r._M_ptr, as 00841 // _M_refcount(__r._M_refcount) did not throw. 00842 _M_ptr = __r._M_ptr; 00843 } 00844 00845 // If an exception is thrown this constructor has no effect. 00846 template<typename _Tp1, typename _Del> 00847 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) 00848 : _M_ptr(__r.get()), _M_refcount() 00849 { 00850 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 00851 auto __tmp = std::__addressof(*__r.get()); 00852 _M_refcount = __shared_count<_Lp>(std::move(__r)); 00853 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); 00854 } 00855 00856 #if _GLIBCXX_USE_DEPRECATED 00857 // Postcondition: use_count() == 1 and __r.get() == 0 00858 template<typename _Tp1> 00859 __shared_ptr(std::auto_ptr<_Tp1>&& __r); 00860 #endif 00861 00862 /* TODO: use delegating constructor */ 00863 constexpr __shared_ptr(nullptr_t) noexcept 00864 : _M_ptr(0), _M_refcount() 00865 { } 00866 00867 template<typename _Tp1> 00868 __shared_ptr& 00869 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 00870 { 00871 _M_ptr = __r._M_ptr; 00872 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 00873 return *this; 00874 } 00875 00876 #if _GLIBCXX_USE_DEPRECATED 00877 template<typename _Tp1> 00878 __shared_ptr& 00879 operator=(std::auto_ptr<_Tp1>&& __r) 00880 { 00881 __shared_ptr(std::move(__r)).swap(*this); 00882 return *this; 00883 } 00884 #endif 00885 00886 __shared_ptr& 00887 operator=(__shared_ptr&& __r) noexcept 00888 { 00889 __shared_ptr(std::move(__r)).swap(*this); 00890 return *this; 00891 } 00892 00893 template<class _Tp1> 00894 __shared_ptr& 00895 operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 00896 { 00897 __shared_ptr(std::move(__r)).swap(*this); 00898 return *this; 00899 } 00900 00901 template<typename _Tp1, typename _Del> 00902 __shared_ptr& 00903 operator=(std::unique_ptr<_Tp1, _Del>&& __r) 00904 { 00905 __shared_ptr(std::move(__r)).swap(*this); 00906 return *this; 00907 } 00908 00909 void 00910 reset() noexcept 00911 { __shared_ptr().swap(*this); } 00912 00913 template<typename _Tp1> 00914 void 00915 reset(_Tp1* __p) // _Tp1 must be complete. 00916 { 00917 // Catch self-reset errors. 00918 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); 00919 __shared_ptr(__p).swap(*this); 00920 } 00921 00922 template<typename _Tp1, typename _Deleter> 00923 void 00924 reset(_Tp1* __p, _Deleter __d) 00925 { __shared_ptr(__p, __d).swap(*this); } 00926 00927 template<typename _Tp1, typename _Deleter, typename _Alloc> 00928 void 00929 reset(_Tp1* __p, _Deleter __d, _Alloc __a) 00930 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); } 00931 00932 // Allow class instantiation when _Tp is [cv-qual] void. 00933 typename std::add_lvalue_reference<_Tp>::type 00934 operator*() const noexcept 00935 { 00936 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 00937 return *_M_ptr; 00938 } 00939 00940 _Tp* 00941 operator->() const noexcept 00942 { 00943 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 00944 return _M_ptr; 00945 } 00946 00947 _Tp* 00948 get() const noexcept 00949 { return _M_ptr; } 00950 00951 explicit operator bool() const // never throws 00952 { return _M_ptr == 0 ? false : true; } 00953 00954 bool 00955 unique() const noexcept 00956 { return _M_refcount._M_unique(); } 00957 00958 long 00959 use_count() const noexcept 00960 { return _M_refcount._M_get_use_count(); } 00961 00962 void 00963 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 00964 { 00965 std::swap(_M_ptr, __other._M_ptr); 00966 _M_refcount._M_swap(__other._M_refcount); 00967 } 00968 00969 template<typename _Tp1> 00970 bool 00971 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const 00972 { return _M_refcount._M_less(__rhs._M_refcount); } 00973 00974 template<typename _Tp1> 00975 bool 00976 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const 00977 { return _M_refcount._M_less(__rhs._M_refcount); } 00978 00979 #ifdef __GXX_RTTI 00980 protected: 00981 // This constructor is non-standard, it is used by allocate_shared. 00982 template<typename _Alloc, typename... _Args> 00983 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 00984 _Args&&... __args) 00985 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 00986 std::forward<_Args>(__args)...) 00987 { 00988 // _M_ptr needs to point to the newly constructed object. 00989 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 00990 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 00991 _M_ptr = static_cast<_Tp*>(__p); 00992 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 00993 } 00994 #else 00995 template<typename _Alloc> 00996 struct _Deleter 00997 { 00998 void operator()(_Tp* __ptr) 00999 { 01000 typedef allocator_traits<_Alloc> _Alloc_traits; 01001 _Alloc_traits::destroy(_M_alloc, __ptr); 01002 _Alloc_traits::deallocate(_M_alloc, __ptr, 1); 01003 } 01004 _Alloc _M_alloc; 01005 }; 01006 01007 template<typename _Alloc, typename... _Args> 01008 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 01009 _Args&&... __args) 01010 : _M_ptr(), _M_refcount() 01011 { 01012 typedef typename _Alloc::template rebind<_Tp>::other _Alloc2; 01013 _Deleter<_Alloc2> __del = { _Alloc2(__a) }; 01014 typedef allocator_traits<_Alloc2> __traits; 01015 _M_ptr = __traits::allocate(__del._M_alloc, 1); 01016 __try 01017 { 01018 // _GLIBCXX_RESOLVE_LIB_DEFECTS 01019 // 2070. allocate_shared should use allocator_traits<A>::construct 01020 __traits::construct(__del._M_alloc, _M_ptr, 01021 std::forward<_Args>(__args)...); 01022 } 01023 __catch(...) 01024 { 01025 __traits::deallocate(__del._M_alloc, _M_ptr, 1); 01026 __throw_exception_again; 01027 } 01028 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc); 01029 _M_refcount._M_swap(__count); 01030 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 01031 } 01032 #endif 01033 01034 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 01035 typename... _Args> 01036 friend __shared_ptr<_Tp1, _Lp1> 01037 __allocate_shared(const _Alloc& __a, _Args&&... __args); 01038 01039 private: 01040 void* 01041 _M_get_deleter(const std::type_info& __ti) const noexcept 01042 { return _M_refcount._M_get_deleter(__ti); } 01043 01044 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 01045 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 01046 01047 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 01048 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 01049 01050 _Tp* _M_ptr; // Contained pointer. 01051 __shared_count<_Lp> _M_refcount; // Reference counter. 01052 }; 01053 01054 01055 // 20.7.2.2.7 shared_ptr comparisons 01056 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01057 inline bool 01058 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 01059 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01060 { return __a.get() == __b.get(); } 01061 01062 template<typename _Tp, _Lock_policy _Lp> 01063 inline bool 01064 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01065 { return !__a; } 01066 01067 template<typename _Tp, _Lock_policy _Lp> 01068 inline bool 01069 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01070 { return !__a; } 01071 01072 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01073 inline bool 01074 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 01075 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01076 { return __a.get() != __b.get(); } 01077 01078 template<typename _Tp, _Lock_policy _Lp> 01079 inline bool 01080 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01081 { return (bool)__a; } 01082 01083 template<typename _Tp, _Lock_policy _Lp> 01084 inline bool 01085 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01086 { return (bool)__a; } 01087 01088 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01089 inline bool 01090 operator<(const __shared_ptr<_Tp1, _Lp>& __a, 01091 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01092 { 01093 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT; 01094 return std::less<_CT>()(__a.get(), __b.get()); 01095 } 01096 01097 template<typename _Tp, _Lock_policy _Lp> 01098 inline bool 01099 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01100 { return std::less<_Tp*>()(__a.get(), nullptr); } 01101 01102 template<typename _Tp, _Lock_policy _Lp> 01103 inline bool 01104 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01105 { return std::less<_Tp*>()(nullptr, __a.get()); } 01106 01107 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01108 inline bool 01109 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 01110 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01111 { return !(__b < __a); } 01112 01113 template<typename _Tp, _Lock_policy _Lp> 01114 inline bool 01115 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01116 { return !(nullptr < __a); } 01117 01118 template<typename _Tp, _Lock_policy _Lp> 01119 inline bool 01120 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01121 { return !(__a < nullptr); } 01122 01123 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01124 inline bool 01125 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 01126 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01127 { return (__b < __a); } 01128 01129 template<typename _Tp, _Lock_policy _Lp> 01130 inline bool 01131 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01132 { return std::less<_Tp*>()(nullptr, __a.get()); } 01133 01134 template<typename _Tp, _Lock_policy _Lp> 01135 inline bool 01136 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01137 { return std::less<_Tp*>()(__a.get(), nullptr); } 01138 01139 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 01140 inline bool 01141 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 01142 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 01143 { return !(__a < __b); } 01144 01145 template<typename _Tp, _Lock_policy _Lp> 01146 inline bool 01147 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 01148 { return !(__a < nullptr); } 01149 01150 template<typename _Tp, _Lock_policy _Lp> 01151 inline bool 01152 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 01153 { return !(nullptr < __a); } 01154 01155 template<typename _Sp> 01156 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 01157 { 01158 bool 01159 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 01160 { 01161 typedef typename _Sp::element_type element_type; 01162 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 01163 } 01164 }; 01165 01166 template<typename _Tp, _Lock_policy _Lp> 01167 struct less<__shared_ptr<_Tp, _Lp>> 01168 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 01169 { }; 01170 01171 // 2.2.3.8 shared_ptr specialized algorithms. 01172 template<typename _Tp, _Lock_policy _Lp> 01173 inline void 01174 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 01175 { __a.swap(__b); } 01176 01177 // 2.2.3.9 shared_ptr casts 01178 01179 // The seemingly equivalent code: 01180 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 01181 // will eventually result in undefined behaviour, attempting to 01182 // delete the same object twice. 01183 /// static_pointer_cast 01184 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 01185 inline __shared_ptr<_Tp, _Lp> 01186 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 01187 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); } 01188 01189 // The seemingly equivalent code: 01190 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 01191 // will eventually result in undefined behaviour, attempting to 01192 // delete the same object twice. 01193 /// const_pointer_cast 01194 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 01195 inline __shared_ptr<_Tp, _Lp> 01196 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 01197 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); } 01198 01199 // The seemingly equivalent code: 01200 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 01201 // will eventually result in undefined behaviour, attempting to 01202 // delete the same object twice. 01203 /// dynamic_pointer_cast 01204 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 01205 inline __shared_ptr<_Tp, _Lp> 01206 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 01207 { 01208 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) 01209 return __shared_ptr<_Tp, _Lp>(__r, __p); 01210 return __shared_ptr<_Tp, _Lp>(); 01211 } 01212 01213 01214 template<typename _Tp, _Lock_policy _Lp> 01215 class __weak_ptr 01216 { 01217 public: 01218 typedef _Tp element_type; 01219 01220 constexpr __weak_ptr() noexcept 01221 : _M_ptr(0), _M_refcount() 01222 { } 01223 01224 __weak_ptr(const __weak_ptr&) noexcept = default; 01225 __weak_ptr& operator=(const __weak_ptr&) noexcept = default; 01226 ~__weak_ptr() = default; 01227 01228 // The "obvious" converting constructor implementation: 01229 // 01230 // template<typename _Tp1> 01231 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 01232 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 01233 // { } 01234 // 01235 // has a serious problem. 01236 // 01237 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 01238 // conversion may require access to *__r._M_ptr (virtual inheritance). 01239 // 01240 // It is not possible to avoid spurious access violations since 01241 // in multithreaded programs __r._M_ptr may be invalidated at any point. 01242 template<typename _Tp1, typename = typename 01243 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 01244 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 01245 : _M_refcount(__r._M_refcount) 01246 { _M_ptr = __r.lock().get(); } 01247 01248 template<typename _Tp1, typename = typename 01249 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type> 01250 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 01251 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 01252 { } 01253 01254 template<typename _Tp1> 01255 __weak_ptr& 01256 operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 01257 { 01258 _M_ptr = __r.lock().get(); 01259 _M_refcount = __r._M_refcount; 01260 return *this; 01261 } 01262 01263 template<typename _Tp1> 01264 __weak_ptr& 01265 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 01266 { 01267 _M_ptr = __r._M_ptr; 01268 _M_refcount = __r._M_refcount; 01269 return *this; 01270 } 01271 01272 __shared_ptr<_Tp, _Lp> 01273 lock() const noexcept 01274 { 01275 #ifdef __GTHREADS 01276 // Optimization: avoid throw overhead. 01277 if (expired()) 01278 return __shared_ptr<element_type, _Lp>(); 01279 01280 __try 01281 { 01282 return __shared_ptr<element_type, _Lp>(*this); 01283 } 01284 __catch(const bad_weak_ptr&) 01285 { 01286 // Q: How can we get here? 01287 // A: Another thread may have invalidated r after the 01288 // use_count test above. 01289 return __shared_ptr<element_type, _Lp>(); 01290 } 01291 01292 #else 01293 // Optimization: avoid try/catch overhead when single threaded. 01294 return expired() ? __shared_ptr<element_type, _Lp>() 01295 : __shared_ptr<element_type, _Lp>(*this); 01296 01297 #endif 01298 } // XXX MT 01299 01300 long 01301 use_count() const noexcept 01302 { return _M_refcount._M_get_use_count(); } 01303 01304 bool 01305 expired() const noexcept 01306 { return _M_refcount._M_get_use_count() == 0; } 01307 01308 template<typename _Tp1> 01309 bool 01310 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const 01311 { return _M_refcount._M_less(__rhs._M_refcount); } 01312 01313 template<typename _Tp1> 01314 bool 01315 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const 01316 { return _M_refcount._M_less(__rhs._M_refcount); } 01317 01318 void 01319 reset() noexcept 01320 { __weak_ptr().swap(*this); } 01321 01322 void 01323 swap(__weak_ptr& __s) noexcept 01324 { 01325 std::swap(_M_ptr, __s._M_ptr); 01326 _M_refcount._M_swap(__s._M_refcount); 01327 } 01328 01329 private: 01330 // Used by __enable_shared_from_this. 01331 void 01332 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 01333 { 01334 _M_ptr = __ptr; 01335 _M_refcount = __refcount; 01336 } 01337 01338 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 01339 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 01340 friend class __enable_shared_from_this<_Tp, _Lp>; 01341 friend class enable_shared_from_this<_Tp>; 01342 01343 _Tp* _M_ptr; // Contained pointer. 01344 __weak_count<_Lp> _M_refcount; // Reference counter. 01345 }; 01346 01347 // 20.7.2.3.6 weak_ptr specialized algorithms. 01348 template<typename _Tp, _Lock_policy _Lp> 01349 inline void 01350 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 01351 { __a.swap(__b); } 01352 01353 template<typename _Tp, typename _Tp1> 01354 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 01355 { 01356 bool 01357 operator()(const _Tp& __lhs, const _Tp& __rhs) const 01358 { return __lhs.owner_before(__rhs); } 01359 01360 bool 01361 operator()(const _Tp& __lhs, const _Tp1& __rhs) const 01362 { return __lhs.owner_before(__rhs); } 01363 01364 bool 01365 operator()(const _Tp1& __lhs, const _Tp& __rhs) const 01366 { return __lhs.owner_before(__rhs); } 01367 }; 01368 01369 template<typename _Tp, _Lock_policy _Lp> 01370 struct owner_less<__shared_ptr<_Tp, _Lp>> 01371 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 01372 { }; 01373 01374 template<typename _Tp, _Lock_policy _Lp> 01375 struct owner_less<__weak_ptr<_Tp, _Lp>> 01376 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 01377 { }; 01378 01379 01380 template<typename _Tp, _Lock_policy _Lp> 01381 class __enable_shared_from_this 01382 { 01383 protected: 01384 constexpr __enable_shared_from_this() noexcept { } 01385 01386 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 01387 01388 __enable_shared_from_this& 01389 operator=(const __enable_shared_from_this&) noexcept 01390 { return *this; } 01391 01392 ~__enable_shared_from_this() { } 01393 01394 public: 01395 __shared_ptr<_Tp, _Lp> 01396 shared_from_this() 01397 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 01398 01399 __shared_ptr<const _Tp, _Lp> 01400 shared_from_this() const 01401 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 01402 01403 private: 01404 template<typename _Tp1> 01405 void 01406 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 01407 { _M_weak_this._M_assign(__p, __n); } 01408 01409 template<typename _Tp1> 01410 friend void 01411 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn, 01412 const __enable_shared_from_this* __pe, 01413 const _Tp1* __px) noexcept 01414 { 01415 if (__pe != 0) 01416 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); 01417 } 01418 01419 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 01420 }; 01421 01422 01423 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 01424 inline __shared_ptr<_Tp, _Lp> 01425 __allocate_shared(const _Alloc& __a, _Args&&... __args) 01426 { 01427 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 01428 std::forward<_Args>(__args)...); 01429 } 01430 01431 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 01432 inline __shared_ptr<_Tp, _Lp> 01433 __make_shared(_Args&&... __args) 01434 { 01435 typedef typename std::remove_const<_Tp>::type _Tp_nc; 01436 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 01437 std::forward<_Args>(__args)...); 01438 } 01439 01440 /// std::hash specialization for __shared_ptr. 01441 template<typename _Tp, _Lock_policy _Lp> 01442 struct hash<__shared_ptr<_Tp, _Lp>> 01443 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 01444 { 01445 size_t 01446 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 01447 { return std::hash<_Tp*>()(__s.get()); } 01448 }; 01449 01450 _GLIBCXX_END_NAMESPACE_VERSION 01451 } // namespace 01452 01453 #endif // _SHARED_PTR_BASE_H