libstdc++
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00001 // shared_ptr and weak_ptr implementation -*- C++ -*- 00002 00003 // Copyright (C) 2007-2017 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 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_H 00050 #define _SHARED_PTR_H 1 00051 00052 #include <bits/shared_ptr_base.h> 00053 00054 namespace std _GLIBCXX_VISIBILITY(default) 00055 { 00056 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00057 00058 /** 00059 * @addtogroup pointer_abstractions 00060 * @{ 00061 */ 00062 00063 /// 20.7.2.2.11 shared_ptr I/O 00064 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp> 00065 inline std::basic_ostream<_Ch, _Tr>& 00066 operator<<(std::basic_ostream<_Ch, _Tr>& __os, 00067 const __shared_ptr<_Tp, _Lp>& __p) 00068 { 00069 __os << __p.get(); 00070 return __os; 00071 } 00072 00073 /// 20.7.2.2.10 shared_ptr get_deleter 00074 template<typename _Del, typename _Tp, _Lock_policy _Lp> 00075 inline _Del* 00076 get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept 00077 { 00078 #if __cpp_rtti 00079 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); 00080 #else 00081 return 0; 00082 #endif 00083 } 00084 00085 00086 /** 00087 * @brief A smart pointer with reference-counted copy semantics. 00088 * 00089 * The object pointed to is deleted when the last shared_ptr pointing to 00090 * it is destroyed or reset. 00091 */ 00092 template<typename _Tp> 00093 class shared_ptr : public __shared_ptr<_Tp> 00094 { 00095 template<typename... _Args> 00096 using _Constructible = typename enable_if< 00097 is_constructible<__shared_ptr<_Tp>, _Args...>::value 00098 >::type; 00099 00100 template<typename _Arg> 00101 using _Assignable = typename enable_if< 00102 is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr& 00103 >::type; 00104 00105 public: 00106 00107 using element_type = typename __shared_ptr<_Tp>::element_type; 00108 00109 #if __cplusplus > 201402L 00110 # define __cpp_lib_shared_ptr_weak_type 201606 00111 using weak_type = weak_ptr<_Tp>; 00112 #endif 00113 /** 00114 * @brief Construct an empty %shared_ptr. 00115 * @post use_count()==0 && get()==0 00116 */ 00117 constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { } 00118 00119 shared_ptr(const shared_ptr&) noexcept = default; 00120 00121 /** 00122 * @brief Construct a %shared_ptr that owns the pointer @a __p. 00123 * @param __p A pointer that is convertible to element_type*. 00124 * @post use_count() == 1 && get() == __p 00125 * @throw std::bad_alloc, in which case @c delete @a __p is called. 00126 */ 00127 template<typename _Yp, typename = _Constructible<_Yp*>> 00128 explicit 00129 shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { } 00130 00131 /** 00132 * @brief Construct a %shared_ptr that owns the pointer @a __p 00133 * and the deleter @a __d. 00134 * @param __p A pointer. 00135 * @param __d A deleter. 00136 * @post use_count() == 1 && get() == __p 00137 * @throw std::bad_alloc, in which case @a __d(__p) is called. 00138 * 00139 * Requirements: _Deleter's copy constructor and destructor must 00140 * not throw 00141 * 00142 * __shared_ptr will release __p by calling __d(__p) 00143 */ 00144 template<typename _Yp, typename _Deleter, 00145 typename = _Constructible<_Yp*, _Deleter>> 00146 shared_ptr(_Yp* __p, _Deleter __d) 00147 : __shared_ptr<_Tp>(__p, std::move(__d)) { } 00148 00149 /** 00150 * @brief Construct a %shared_ptr that owns a null pointer 00151 * and the deleter @a __d. 00152 * @param __p A null pointer constant. 00153 * @param __d A deleter. 00154 * @post use_count() == 1 && get() == __p 00155 * @throw std::bad_alloc, in which case @a __d(__p) is called. 00156 * 00157 * Requirements: _Deleter's copy constructor and destructor must 00158 * not throw 00159 * 00160 * The last owner will call __d(__p) 00161 */ 00162 template<typename _Deleter> 00163 shared_ptr(nullptr_t __p, _Deleter __d) 00164 : __shared_ptr<_Tp>(__p, std::move(__d)) { } 00165 00166 /** 00167 * @brief Construct a %shared_ptr that owns the pointer @a __p 00168 * and the deleter @a __d. 00169 * @param __p A pointer. 00170 * @param __d A deleter. 00171 * @param __a An allocator. 00172 * @post use_count() == 1 && get() == __p 00173 * @throw std::bad_alloc, in which case @a __d(__p) is called. 00174 * 00175 * Requirements: _Deleter's copy constructor and destructor must 00176 * not throw _Alloc's copy constructor and destructor must not 00177 * throw. 00178 * 00179 * __shared_ptr will release __p by calling __d(__p) 00180 */ 00181 template<typename _Yp, typename _Deleter, typename _Alloc, 00182 typename = _Constructible<_Yp*, _Deleter, _Alloc>> 00183 shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a) 00184 : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } 00185 00186 /** 00187 * @brief Construct a %shared_ptr that owns a null pointer 00188 * and the deleter @a __d. 00189 * @param __p A null pointer constant. 00190 * @param __d A deleter. 00191 * @param __a An allocator. 00192 * @post use_count() == 1 && get() == __p 00193 * @throw std::bad_alloc, in which case @a __d(__p) is called. 00194 * 00195 * Requirements: _Deleter's copy constructor and destructor must 00196 * not throw _Alloc's copy constructor and destructor must not 00197 * throw. 00198 * 00199 * The last owner will call __d(__p) 00200 */ 00201 template<typename _Deleter, typename _Alloc> 00202 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 00203 : __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { } 00204 00205 // Aliasing constructor 00206 00207 /** 00208 * @brief Constructs a %shared_ptr instance that stores @a __p 00209 * and shares ownership with @a __r. 00210 * @param __r A %shared_ptr. 00211 * @param __p A pointer that will remain valid while @a *__r is valid. 00212 * @post get() == __p && use_count() == __r.use_count() 00213 * 00214 * This can be used to construct a @c shared_ptr to a sub-object 00215 * of an object managed by an existing @c shared_ptr. 00216 * 00217 * @code 00218 * shared_ptr< pair<int,int> > pii(new pair<int,int>()); 00219 * shared_ptr<int> pi(pii, &pii->first); 00220 * assert(pii.use_count() == 2); 00221 * @endcode 00222 */ 00223 template<typename _Yp> 00224 shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept 00225 : __shared_ptr<_Tp>(__r, __p) { } 00226 00227 /** 00228 * @brief If @a __r is empty, constructs an empty %shared_ptr; 00229 * otherwise construct a %shared_ptr that shares ownership 00230 * with @a __r. 00231 * @param __r A %shared_ptr. 00232 * @post get() == __r.get() && use_count() == __r.use_count() 00233 */ 00234 template<typename _Yp, 00235 typename = _Constructible<const shared_ptr<_Yp>&>> 00236 shared_ptr(const shared_ptr<_Yp>& __r) noexcept 00237 : __shared_ptr<_Tp>(__r) { } 00238 00239 /** 00240 * @brief Move-constructs a %shared_ptr instance from @a __r. 00241 * @param __r A %shared_ptr rvalue. 00242 * @post *this contains the old value of @a __r, @a __r is empty. 00243 */ 00244 shared_ptr(shared_ptr&& __r) noexcept 00245 : __shared_ptr<_Tp>(std::move(__r)) { } 00246 00247 /** 00248 * @brief Move-constructs a %shared_ptr instance from @a __r. 00249 * @param __r A %shared_ptr rvalue. 00250 * @post *this contains the old value of @a __r, @a __r is empty. 00251 */ 00252 template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>> 00253 shared_ptr(shared_ptr<_Yp>&& __r) noexcept 00254 : __shared_ptr<_Tp>(std::move(__r)) { } 00255 00256 /** 00257 * @brief Constructs a %shared_ptr that shares ownership with @a __r 00258 * and stores a copy of the pointer stored in @a __r. 00259 * @param __r A weak_ptr. 00260 * @post use_count() == __r.use_count() 00261 * @throw bad_weak_ptr when __r.expired(), 00262 * in which case the constructor has no effect. 00263 */ 00264 template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> 00265 explicit shared_ptr(const weak_ptr<_Yp>& __r) 00266 : __shared_ptr<_Tp>(__r) { } 00267 00268 #if _GLIBCXX_USE_DEPRECATED 00269 template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>> 00270 shared_ptr(auto_ptr<_Yp>&& __r); 00271 #endif 00272 00273 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00274 // 2399. shared_ptr's constructor from unique_ptr should be constrained 00275 template<typename _Yp, typename _Del, 00276 typename = _Constructible<unique_ptr<_Yp, _Del>>> 00277 shared_ptr(unique_ptr<_Yp, _Del>&& __r) 00278 : __shared_ptr<_Tp>(std::move(__r)) { } 00279 00280 #if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED 00281 // This non-standard constructor exists to support conversions that 00282 // were possible in C++11 and C++14 but are ill-formed in C++17. 00283 // If an exception is thrown this constructor has no effect. 00284 template<typename _Yp, typename _Del, 00285 _Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0> 00286 shared_ptr(unique_ptr<_Yp, _Del>&& __r) 00287 : __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { } 00288 #endif 00289 00290 /** 00291 * @brief Construct an empty %shared_ptr. 00292 * @post use_count() == 0 && get() == nullptr 00293 */ 00294 constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { } 00295 00296 shared_ptr& operator=(const shared_ptr&) noexcept = default; 00297 00298 template<typename _Yp> 00299 _Assignable<const shared_ptr<_Yp>&> 00300 operator=(const shared_ptr<_Yp>& __r) noexcept 00301 { 00302 this->__shared_ptr<_Tp>::operator=(__r); 00303 return *this; 00304 } 00305 00306 #if _GLIBCXX_USE_DEPRECATED 00307 template<typename _Yp> 00308 _Assignable<auto_ptr<_Yp>> 00309 operator=(auto_ptr<_Yp>&& __r) 00310 { 00311 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 00312 return *this; 00313 } 00314 #endif 00315 00316 shared_ptr& 00317 operator=(shared_ptr&& __r) noexcept 00318 { 00319 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 00320 return *this; 00321 } 00322 00323 template<class _Yp> 00324 _Assignable<shared_ptr<_Yp>> 00325 operator=(shared_ptr<_Yp>&& __r) noexcept 00326 { 00327 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 00328 return *this; 00329 } 00330 00331 template<typename _Yp, typename _Del> 00332 _Assignable<unique_ptr<_Yp, _Del>> 00333 operator=(unique_ptr<_Yp, _Del>&& __r) 00334 { 00335 this->__shared_ptr<_Tp>::operator=(std::move(__r)); 00336 return *this; 00337 } 00338 00339 private: 00340 // This constructor is non-standard, it is used by allocate_shared. 00341 template<typename _Alloc, typename... _Args> 00342 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 00343 _Args&&... __args) 00344 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...) 00345 { } 00346 00347 template<typename _Yp, typename _Alloc, typename... _Args> 00348 friend shared_ptr<_Yp> 00349 allocate_shared(const _Alloc& __a, _Args&&... __args); 00350 00351 // This constructor is non-standard, it is used by weak_ptr::lock(). 00352 shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) 00353 : __shared_ptr<_Tp>(__r, std::nothrow) { } 00354 00355 friend class weak_ptr<_Tp>; 00356 }; 00357 00358 #if __cpp_deduction_guides >= 201606 00359 template<typename _Tp> 00360 shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>; 00361 template<typename _Tp, typename _Del> 00362 shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>; 00363 #endif 00364 00365 // 20.7.2.2.7 shared_ptr comparisons 00366 template<typename _Tp, typename _Up> 00367 inline bool 00368 operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00369 { return __a.get() == __b.get(); } 00370 00371 template<typename _Tp> 00372 inline bool 00373 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00374 { return !__a; } 00375 00376 template<typename _Tp> 00377 inline bool 00378 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00379 { return !__a; } 00380 00381 template<typename _Tp, typename _Up> 00382 inline bool 00383 operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00384 { return __a.get() != __b.get(); } 00385 00386 template<typename _Tp> 00387 inline bool 00388 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00389 { return (bool)__a; } 00390 00391 template<typename _Tp> 00392 inline bool 00393 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00394 { return (bool)__a; } 00395 00396 template<typename _Tp, typename _Up> 00397 inline bool 00398 operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00399 { 00400 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 00401 using _Up_elt = typename shared_ptr<_Up>::element_type; 00402 using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type; 00403 return less<_Vp>()(__a.get(), __b.get()); 00404 } 00405 00406 template<typename _Tp> 00407 inline bool 00408 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00409 { 00410 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 00411 return less<_Tp_elt*>()(__a.get(), nullptr); 00412 } 00413 00414 template<typename _Tp> 00415 inline bool 00416 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00417 { 00418 using _Tp_elt = typename shared_ptr<_Tp>::element_type; 00419 return less<_Tp_elt*>()(nullptr, __a.get()); 00420 } 00421 00422 template<typename _Tp, typename _Up> 00423 inline bool 00424 operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00425 { return !(__b < __a); } 00426 00427 template<typename _Tp> 00428 inline bool 00429 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00430 { return !(nullptr < __a); } 00431 00432 template<typename _Tp> 00433 inline bool 00434 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00435 { return !(__a < nullptr); } 00436 00437 template<typename _Tp, typename _Up> 00438 inline bool 00439 operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00440 { return (__b < __a); } 00441 00442 template<typename _Tp> 00443 inline bool 00444 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00445 { return nullptr < __a; } 00446 00447 template<typename _Tp> 00448 inline bool 00449 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00450 { return __a < nullptr; } 00451 00452 template<typename _Tp, typename _Up> 00453 inline bool 00454 operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept 00455 { return !(__a < __b); } 00456 00457 template<typename _Tp> 00458 inline bool 00459 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept 00460 { return !(__a < nullptr); } 00461 00462 template<typename _Tp> 00463 inline bool 00464 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept 00465 { return !(nullptr < __a); } 00466 00467 template<typename _Tp> 00468 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>> 00469 { }; 00470 00471 // 20.7.2.2.8 shared_ptr specialized algorithms. 00472 template<typename _Tp> 00473 inline void 00474 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept 00475 { __a.swap(__b); } 00476 00477 // 20.7.2.2.9 shared_ptr casts. 00478 template<typename _Tp, typename _Up> 00479 inline shared_ptr<_Tp> 00480 static_pointer_cast(const shared_ptr<_Up>& __r) noexcept 00481 { 00482 using _Sp = shared_ptr<_Tp>; 00483 return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get())); 00484 } 00485 00486 template<typename _Tp, typename _Up> 00487 inline shared_ptr<_Tp> 00488 const_pointer_cast(const shared_ptr<_Up>& __r) noexcept 00489 { 00490 using _Sp = shared_ptr<_Tp>; 00491 return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get())); 00492 } 00493 00494 template<typename _Tp, typename _Up> 00495 inline shared_ptr<_Tp> 00496 dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept 00497 { 00498 using _Sp = shared_ptr<_Tp>; 00499 if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get())) 00500 return _Sp(__r, __p); 00501 return _Sp(); 00502 } 00503 00504 #if __cplusplus > 201402L 00505 template<typename _Tp, typename _Up> 00506 inline shared_ptr<_Tp> 00507 reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept 00508 { 00509 using _Sp = shared_ptr<_Tp>; 00510 return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get())); 00511 } 00512 #endif 00513 00514 /** 00515 * @brief A smart pointer with weak semantics. 00516 * 00517 * With forwarding constructors and assignment operators. 00518 */ 00519 template<typename _Tp> 00520 class weak_ptr : public __weak_ptr<_Tp> 00521 { 00522 template<typename _Arg> 00523 using _Constructible = typename enable_if< 00524 is_constructible<__weak_ptr<_Tp>, _Arg>::value 00525 >::type; 00526 00527 template<typename _Arg> 00528 using _Assignable = typename enable_if< 00529 is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr& 00530 >::type; 00531 00532 public: 00533 constexpr weak_ptr() noexcept = default; 00534 00535 template<typename _Yp, 00536 typename = _Constructible<const shared_ptr<_Yp>&>> 00537 weak_ptr(const shared_ptr<_Yp>& __r) noexcept 00538 : __weak_ptr<_Tp>(__r) { } 00539 00540 weak_ptr(const weak_ptr&) noexcept = default; 00541 00542 template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>> 00543 weak_ptr(const weak_ptr<_Yp>& __r) noexcept 00544 : __weak_ptr<_Tp>(__r) { } 00545 00546 weak_ptr(weak_ptr&&) noexcept = default; 00547 00548 template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>> 00549 weak_ptr(weak_ptr<_Yp>&& __r) noexcept 00550 : __weak_ptr<_Tp>(std::move(__r)) { } 00551 00552 weak_ptr& 00553 operator=(const weak_ptr& __r) noexcept = default; 00554 00555 template<typename _Yp> 00556 _Assignable<const weak_ptr<_Yp>&> 00557 operator=(const weak_ptr<_Yp>& __r) noexcept 00558 { 00559 this->__weak_ptr<_Tp>::operator=(__r); 00560 return *this; 00561 } 00562 00563 template<typename _Yp> 00564 _Assignable<const shared_ptr<_Yp>&> 00565 operator=(const shared_ptr<_Yp>& __r) noexcept 00566 { 00567 this->__weak_ptr<_Tp>::operator=(__r); 00568 return *this; 00569 } 00570 00571 weak_ptr& 00572 operator=(weak_ptr&& __r) noexcept = default; 00573 00574 template<typename _Yp> 00575 _Assignable<weak_ptr<_Yp>> 00576 operator=(weak_ptr<_Yp>&& __r) noexcept 00577 { 00578 this->__weak_ptr<_Tp>::operator=(std::move(__r)); 00579 return *this; 00580 } 00581 00582 shared_ptr<_Tp> 00583 lock() const noexcept 00584 { return shared_ptr<_Tp>(*this, std::nothrow); } 00585 }; 00586 00587 #if __cpp_deduction_guides >= 201606 00588 template<typename _Tp> 00589 weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>; 00590 #endif 00591 00592 // 20.7.2.3.6 weak_ptr specialized algorithms. 00593 template<typename _Tp> 00594 inline void 00595 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept 00596 { __a.swap(__b); } 00597 00598 00599 /// Primary template owner_less 00600 template<typename _Tp = void> 00601 struct owner_less; 00602 00603 /// Void specialization of owner_less 00604 template<> 00605 struct owner_less<void> : _Sp_owner_less<void, void> 00606 { }; 00607 00608 /// Partial specialization of owner_less for shared_ptr. 00609 template<typename _Tp> 00610 struct owner_less<shared_ptr<_Tp>> 00611 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>> 00612 { }; 00613 00614 /// Partial specialization of owner_less for weak_ptr. 00615 template<typename _Tp> 00616 struct owner_less<weak_ptr<_Tp>> 00617 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>> 00618 { }; 00619 00620 /** 00621 * @brief Base class allowing use of member function shared_from_this. 00622 */ 00623 template<typename _Tp> 00624 class enable_shared_from_this 00625 { 00626 protected: 00627 constexpr enable_shared_from_this() noexcept { } 00628 00629 enable_shared_from_this(const enable_shared_from_this&) noexcept { } 00630 00631 enable_shared_from_this& 00632 operator=(const enable_shared_from_this&) noexcept 00633 { return *this; } 00634 00635 ~enable_shared_from_this() { } 00636 00637 public: 00638 shared_ptr<_Tp> 00639 shared_from_this() 00640 { return shared_ptr<_Tp>(this->_M_weak_this); } 00641 00642 shared_ptr<const _Tp> 00643 shared_from_this() const 00644 { return shared_ptr<const _Tp>(this->_M_weak_this); } 00645 00646 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11 00647 #define __cpp_lib_enable_shared_from_this 201603 00648 weak_ptr<_Tp> 00649 weak_from_this() noexcept 00650 { return this->_M_weak_this; } 00651 00652 weak_ptr<const _Tp> 00653 weak_from_this() const noexcept 00654 { return this->_M_weak_this; } 00655 #endif 00656 00657 private: 00658 template<typename _Tp1> 00659 void 00660 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept 00661 { _M_weak_this._M_assign(__p, __n); } 00662 00663 // Found by ADL when this is an associated class. 00664 friend const enable_shared_from_this* 00665 __enable_shared_from_this_base(const __shared_count<>&, 00666 const enable_shared_from_this* __p) 00667 { return __p; } 00668 00669 template<typename, _Lock_policy> 00670 friend class __shared_ptr; 00671 00672 mutable weak_ptr<_Tp> _M_weak_this; 00673 }; 00674 00675 /** 00676 * @brief Create an object that is owned by a shared_ptr. 00677 * @param __a An allocator. 00678 * @param __args Arguments for the @a _Tp object's constructor. 00679 * @return A shared_ptr that owns the newly created object. 00680 * @throw An exception thrown from @a _Alloc::allocate or from the 00681 * constructor of @a _Tp. 00682 * 00683 * A copy of @a __a will be used to allocate memory for the shared_ptr 00684 * and the new object. 00685 */ 00686 template<typename _Tp, typename _Alloc, typename... _Args> 00687 inline shared_ptr<_Tp> 00688 allocate_shared(const _Alloc& __a, _Args&&... __args) 00689 { 00690 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a, 00691 std::forward<_Args>(__args)...); 00692 } 00693 00694 /** 00695 * @brief Create an object that is owned by a shared_ptr. 00696 * @param __args Arguments for the @a _Tp object's constructor. 00697 * @return A shared_ptr that owns the newly created object. 00698 * @throw std::bad_alloc, or an exception thrown from the 00699 * constructor of @a _Tp. 00700 */ 00701 template<typename _Tp, typename... _Args> 00702 inline shared_ptr<_Tp> 00703 make_shared(_Args&&... __args) 00704 { 00705 typedef typename std::remove_const<_Tp>::type _Tp_nc; 00706 return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(), 00707 std::forward<_Args>(__args)...); 00708 } 00709 00710 /// std::hash specialization for shared_ptr. 00711 template<typename _Tp> 00712 struct hash<shared_ptr<_Tp>> 00713 : public __hash_base<size_t, shared_ptr<_Tp>> 00714 { 00715 size_t 00716 operator()(const shared_ptr<_Tp>& __s) const noexcept 00717 { 00718 return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get()); 00719 } 00720 }; 00721 00722 // @} group pointer_abstractions 00723 00724 _GLIBCXX_END_NAMESPACE_VERSION 00725 } // namespace 00726 00727 #endif // _SHARED_PTR_H