1 // shared_ptr and weak_ptr implementation -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 // GCC Note: Based on files from version 1.32.0 of the Boost library.
28 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
31 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32 // Copyright (C) 2001, 2002, 2003 Peter Dimov
35 // Copyright (C) 2001, 2002, 2003 Peter Dimov
37 // enable_shared_from_this.hpp
38 // Copyright (C) 2002 Peter Dimov
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)
44 /** @file bits/shared_ptr.h
45 * This is an internal header file, included by other library headers.
46 * Do not attempt to use it directly. @headername{memory}
50 #define _SHARED_PTR_H 1
52 #include <bits/shared_ptr_base.h>
54 _GLIBCXX_BEGIN_NAMESPACE(std)
57 * @addtogroup pointer_abstractions
61 /// 2.2.3.7 shared_ptr I/O
62 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
63 inline std::basic_ostream<_Ch, _Tr>&
64 operator<<(std::basic_ostream<_Ch, _Tr>& __os,
65 const __shared_ptr<_Tp, _Lp>& __p)
71 /// 2.2.3.10 shared_ptr get_deleter (experimental)
72 template<typename _Del, typename _Tp, _Lock_policy _Lp>
74 get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
77 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
85 * @brief A smart pointer with reference-counted copy semantics.
87 * The object pointed to is deleted when the last shared_ptr pointing to
88 * it is destroyed or reset.
90 template<typename _Tp>
91 class shared_ptr : public __shared_ptr<_Tp>
95 * @brief Construct an empty %shared_ptr.
96 * @post use_count()==0 && get()==0
98 constexpr shared_ptr()
99 : __shared_ptr<_Tp>() { }
102 * @brief Construct a %shared_ptr that owns the pointer @a __p.
103 * @param __p A pointer that is convertible to element_type*.
104 * @post use_count() == 1 && get() == __p
105 * @throw std::bad_alloc, in which case @c delete @a __p is called.
107 template<typename _Tp1>
108 explicit shared_ptr(_Tp1* __p)
109 : __shared_ptr<_Tp>(__p) { }
112 * @brief Construct a %shared_ptr that owns the pointer @a __p
113 * and the deleter @a __d.
114 * @param __p A pointer.
115 * @param __d A deleter.
116 * @post use_count() == 1 && get() == __p
117 * @throw std::bad_alloc, in which case @a __d(__p) is called.
119 * Requirements: _Deleter's copy constructor and destructor must
122 * __shared_ptr will release __p by calling __d(__p)
124 template<typename _Tp1, typename _Deleter>
125 shared_ptr(_Tp1* __p, _Deleter __d)
126 : __shared_ptr<_Tp>(__p, __d) { }
129 * @brief Construct a %shared_ptr that owns a null pointer
130 * and the deleter @a __d.
131 * @param __p A null pointer constant.
132 * @param __d A deleter.
133 * @post use_count() == 1 && get() == __p
134 * @throw std::bad_alloc, in which case @a __d(__p) is called.
136 * Requirements: _Deleter's copy constructor and destructor must
139 * The last owner will call __d(__p)
141 template<typename _Deleter>
142 shared_ptr(nullptr_t __p, _Deleter __d)
143 : __shared_ptr<_Tp>(__p, __d) { }
146 * @brief Construct a %shared_ptr that owns the pointer @a __p
147 * and the deleter @a __d.
148 * @param __p A pointer.
149 * @param __d A deleter.
150 * @param __a An allocator.
151 * @post use_count() == 1 && get() == __p
152 * @throw std::bad_alloc, in which case @a __d(__p) is called.
154 * Requirements: _Deleter's copy constructor and destructor must
155 * not throw _Alloc's copy constructor and destructor must not
158 * __shared_ptr will release __p by calling __d(__p)
160 template<typename _Tp1, typename _Deleter, typename _Alloc>
161 shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
162 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
165 * @brief Construct a %shared_ptr that owns a null pointer
166 * and the deleter @a __d.
167 * @param __p A null pointer constant.
168 * @param __d A deleter.
169 * @param __a An allocator.
170 * @post use_count() == 1 && get() == __p
171 * @throw std::bad_alloc, in which case @a __d(__p) is called.
173 * Requirements: _Deleter's copy constructor and destructor must
174 * not throw _Alloc's copy constructor and destructor must not
177 * The last owner will call __d(__p)
179 template<typename _Deleter, typename _Alloc>
180 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
181 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
183 // Aliasing constructor
186 * @brief Constructs a %shared_ptr instance that stores @a __p
187 * and shares ownership with @a __r.
188 * @param __r A %shared_ptr.
189 * @param __p A pointer that will remain valid while @a *__r is valid.
190 * @post get() == __p && use_count() == __r.use_count()
192 * This can be used to construct a @c shared_ptr to a sub-object
193 * of an object managed by an existing @c shared_ptr.
196 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
197 * shared_ptr<int> pi(pii, &pii->first);
198 * assert(pii.use_count() == 2);
201 template<typename _Tp1>
202 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
203 : __shared_ptr<_Tp>(__r, __p) { }
206 * @brief If @a __r is empty, constructs an empty %shared_ptr;
207 * otherwise construct a %shared_ptr that shares ownership
209 * @param __r A %shared_ptr.
210 * @post get() == __r.get() && use_count() == __r.use_count()
212 template<typename _Tp1, typename = typename
213 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
214 shared_ptr(const shared_ptr<_Tp1>& __r)
215 : __shared_ptr<_Tp>(__r) { }
218 * @brief Move-constructs a %shared_ptr instance from @a __r.
219 * @param __r A %shared_ptr rvalue.
220 * @post *this contains the old value of @a __r, @a __r is empty.
222 shared_ptr(shared_ptr&& __r)
223 : __shared_ptr<_Tp>(std::move(__r)) { }
226 * @brief Move-constructs a %shared_ptr instance from @a __r.
227 * @param __r A %shared_ptr rvalue.
228 * @post *this contains the old value of @a __r, @a __r is empty.
230 template<typename _Tp1, typename = typename
231 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
232 shared_ptr(shared_ptr<_Tp1>&& __r)
233 : __shared_ptr<_Tp>(std::move(__r)) { }
236 * @brief Constructs a %shared_ptr that shares ownership with @a __r
237 * and stores a copy of the pointer stored in @a __r.
238 * @param __r A weak_ptr.
239 * @post use_count() == __r.use_count()
240 * @throw bad_weak_ptr when __r.expired(),
241 * in which case the constructor has no effect.
243 template<typename _Tp1>
244 explicit shared_ptr(const weak_ptr<_Tp1>& __r)
245 : __shared_ptr<_Tp>(__r) { }
247 #if _GLIBCXX_DEPRECATED
248 template<typename _Tp1>
249 shared_ptr(std::auto_ptr<_Tp1>&& __r)
250 : __shared_ptr<_Tp>(std::move(__r)) { }
253 template<typename _Tp1, typename _Del>
254 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
255 : __shared_ptr<_Tp>(std::move(__r)) { }
258 * @brief Construct an empty %shared_ptr.
259 * @param __p A null pointer constant.
260 * @post use_count() == 0 && get() == nullptr
262 constexpr shared_ptr(nullptr_t __p)
263 : __shared_ptr<_Tp>(__p) { }
265 template<typename _Tp1>
267 operator=(const shared_ptr<_Tp1>& __r) // never throws
269 this->__shared_ptr<_Tp>::operator=(__r);
273 #if _GLIBCXX_DEPRECATED
274 template<typename _Tp1>
276 operator=(std::auto_ptr<_Tp1>&& __r)
278 this->__shared_ptr<_Tp>::operator=(std::move(__r));
284 operator=(shared_ptr&& __r)
286 this->__shared_ptr<_Tp>::operator=(std::move(__r));
292 operator=(shared_ptr<_Tp1>&& __r)
294 this->__shared_ptr<_Tp>::operator=(std::move(__r));
298 template<typename _Tp1, typename _Del>
300 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
302 this->__shared_ptr<_Tp>::operator=(std::move(__r));
307 // This constructor is non-standard, it is used by allocate_shared.
308 template<typename _Alloc, typename... _Args>
309 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
311 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
314 template<typename _Tp1, typename _Alloc, typename... _Args>
315 friend shared_ptr<_Tp1>
316 allocate_shared(const _Alloc& __a, _Args&&... __args);
319 // 20.8.13.2.7 shared_ptr comparisons
320 template<typename _Tp1, typename _Tp2>
322 operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
323 { return __a.get() == __b.get(); }
325 template<typename _Tp>
327 operator==(const shared_ptr<_Tp>& __a, nullptr_t)
328 { return __a.get() == nullptr; }
330 template<typename _Tp>
332 operator==(nullptr_t, const shared_ptr<_Tp>& __b)
333 { return nullptr == __b.get(); }
335 template<typename _Tp1, typename _Tp2>
337 operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
338 { return __a.get() != __b.get(); }
340 template<typename _Tp>
342 operator!=(const shared_ptr<_Tp>& __a, nullptr_t)
343 { return __a.get() != nullptr; }
345 template<typename _Tp>
347 operator!=(nullptr_t, const shared_ptr<_Tp>& __b)
348 { return nullptr != __b.get(); }
350 template<typename _Tp1, typename _Tp2>
352 operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
353 { return __a.get() < __b.get(); }
355 template<typename _Tp>
356 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
359 // 20.8.13.2.9 shared_ptr specialized algorithms.
360 template<typename _Tp>
362 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
365 // 20.8.13.2.10 shared_ptr casts.
366 template<typename _Tp, typename _Tp1>
367 inline shared_ptr<_Tp>
368 static_pointer_cast(const shared_ptr<_Tp1>& __r)
369 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
371 template<typename _Tp, typename _Tp1>
372 inline shared_ptr<_Tp>
373 const_pointer_cast(const shared_ptr<_Tp1>& __r)
374 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
376 template<typename _Tp, typename _Tp1>
377 inline shared_ptr<_Tp>
378 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
380 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
381 return shared_ptr<_Tp>(__r, __p);
382 return shared_ptr<_Tp>();
387 * @brief A smart pointer with weak semantics.
389 * With forwarding constructors and assignment operators.
391 template<typename _Tp>
392 class weak_ptr : public __weak_ptr<_Tp>
396 : __weak_ptr<_Tp>() { }
398 template<typename _Tp1, typename = typename
399 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
400 weak_ptr(const weak_ptr<_Tp1>& __r)
401 : __weak_ptr<_Tp>(__r) { }
403 template<typename _Tp1, typename = typename
404 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
405 weak_ptr(const shared_ptr<_Tp1>& __r)
406 : __weak_ptr<_Tp>(__r) { }
408 template<typename _Tp1>
410 operator=(const weak_ptr<_Tp1>& __r) // never throws
412 this->__weak_ptr<_Tp>::operator=(__r);
416 template<typename _Tp1>
418 operator=(const shared_ptr<_Tp1>& __r) // never throws
420 this->__weak_ptr<_Tp>::operator=(__r);
425 lock() const // never throws
429 return shared_ptr<_Tp>();
433 return shared_ptr<_Tp>(*this);
435 __catch(const bad_weak_ptr&)
437 return shared_ptr<_Tp>();
440 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
445 // 20.8.13.3.7 weak_ptr specialized algorithms.
446 template<typename _Tp>
448 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
452 /// Primary template owner_less
453 template<typename _Tp>
456 /// Partial specialization of owner_less for shared_ptr.
457 template<typename _Tp>
458 struct owner_less<shared_ptr<_Tp>>
459 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
462 /// Partial specialization of owner_less for weak_ptr.
463 template<typename _Tp>
464 struct owner_less<weak_ptr<_Tp>>
465 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
469 * @brief Base class allowing use of member function shared_from_this.
471 template<typename _Tp>
472 class enable_shared_from_this
475 constexpr enable_shared_from_this() { }
477 enable_shared_from_this(const enable_shared_from_this&) { }
479 enable_shared_from_this&
480 operator=(const enable_shared_from_this&)
483 ~enable_shared_from_this() { }
488 { return shared_ptr<_Tp>(this->_M_weak_this); }
490 shared_ptr<const _Tp>
491 shared_from_this() const
492 { return shared_ptr<const _Tp>(this->_M_weak_this); }
495 template<typename _Tp1>
497 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
498 { _M_weak_this._M_assign(__p, __n); }
500 template<typename _Tp1>
502 __enable_shared_from_this_helper(const __shared_count<>& __pn,
503 const enable_shared_from_this* __pe,
507 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
510 mutable weak_ptr<_Tp> _M_weak_this;
514 * @brief Create an object that is owned by a shared_ptr.
515 * @param __a An allocator.
516 * @param __args Arguments for the @a _Tp object's constructor.
517 * @return A shared_ptr that owns the newly created object.
518 * @throw An exception thrown from @a _Alloc::allocate or from the
519 * constructor of @a _Tp.
521 * A copy of @a __a will be used to allocate memory for the shared_ptr
522 * and the new object.
524 template<typename _Tp, typename _Alloc, typename... _Args>
525 inline shared_ptr<_Tp>
526 allocate_shared(const _Alloc& __a, _Args&&... __args)
528 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
529 std::forward<_Args>(__args)...);
533 * @brief Create an object that is owned by a shared_ptr.
534 * @param __args Arguments for the @a _Tp object's constructor.
535 * @return A shared_ptr that owns the newly created object.
536 * @throw std::bad_alloc, or an exception thrown from the
537 * constructor of @a _Tp.
539 template<typename _Tp, typename... _Args>
540 inline shared_ptr<_Tp>
541 make_shared(_Args&&... __args)
543 typedef typename std::remove_const<_Tp>::type _Tp_nc;
544 return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
545 std::forward<_Args>(__args)...);
548 /// std::hash specialization for shared_ptr.
549 template<typename _Tp>
550 struct hash<shared_ptr<_Tp>>
551 : public std::unary_function<shared_ptr<_Tp>, size_t>
554 operator()(const shared_ptr<_Tp>& __s) const
555 { return std::hash<_Tp*>()(__s.get()); }
558 // @} group pointer_abstractions
560 _GLIBCXX_END_NAMESPACE
562 #endif // _SHARED_PTR_H