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 namespace std _GLIBCXX_VISIBILITY(default)
56 _GLIBCXX_BEGIN_NAMESPACE_VERSION
59 * @addtogroup pointer_abstractions
63 /// 2.2.3.7 shared_ptr I/O
64 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
65 inline std::basic_ostream<_Ch, _Tr>&
66 operator<<(std::basic_ostream<_Ch, _Tr>& __os,
67 const __shared_ptr<_Tp, _Lp>& __p)
73 /// 2.2.3.10 shared_ptr get_deleter (experimental)
74 template<typename _Del, typename _Tp, _Lock_policy _Lp>
76 get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
79 return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
87 * @brief A smart pointer with reference-counted copy semantics.
89 * The object pointed to is deleted when the last shared_ptr pointing to
90 * it is destroyed or reset.
92 template<typename _Tp>
93 class shared_ptr : public __shared_ptr<_Tp>
97 * @brief Construct an empty %shared_ptr.
98 * @post use_count()==0 && get()==0
100 constexpr shared_ptr()
101 : __shared_ptr<_Tp>() { }
104 * @brief Construct a %shared_ptr that owns the pointer @a __p.
105 * @param __p A pointer that is convertible to element_type*.
106 * @post use_count() == 1 && get() == __p
107 * @throw std::bad_alloc, in which case @c delete @a __p is called.
109 template<typename _Tp1>
110 explicit shared_ptr(_Tp1* __p)
111 : __shared_ptr<_Tp>(__p) { }
114 * @brief Construct a %shared_ptr that owns the pointer @a __p
115 * and the deleter @a __d.
116 * @param __p A pointer.
117 * @param __d A deleter.
118 * @post use_count() == 1 && get() == __p
119 * @throw std::bad_alloc, in which case @a __d(__p) is called.
121 * Requirements: _Deleter's copy constructor and destructor must
124 * __shared_ptr will release __p by calling __d(__p)
126 template<typename _Tp1, typename _Deleter>
127 shared_ptr(_Tp1* __p, _Deleter __d)
128 : __shared_ptr<_Tp>(__p, __d) { }
131 * @brief Construct a %shared_ptr that owns a null pointer
132 * and the deleter @a __d.
133 * @param __p A null pointer constant.
134 * @param __d A deleter.
135 * @post use_count() == 1 && get() == __p
136 * @throw std::bad_alloc, in which case @a __d(__p) is called.
138 * Requirements: _Deleter's copy constructor and destructor must
141 * The last owner will call __d(__p)
143 template<typename _Deleter>
144 shared_ptr(nullptr_t __p, _Deleter __d)
145 : __shared_ptr<_Tp>(__p, __d) { }
148 * @brief Construct a %shared_ptr that owns the pointer @a __p
149 * and the deleter @a __d.
150 * @param __p A pointer.
151 * @param __d A deleter.
152 * @param __a An allocator.
153 * @post use_count() == 1 && get() == __p
154 * @throw std::bad_alloc, in which case @a __d(__p) is called.
156 * Requirements: _Deleter's copy constructor and destructor must
157 * not throw _Alloc's copy constructor and destructor must not
160 * __shared_ptr will release __p by calling __d(__p)
162 template<typename _Tp1, typename _Deleter, typename _Alloc>
163 shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
164 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
167 * @brief Construct a %shared_ptr that owns a null pointer
168 * and the deleter @a __d.
169 * @param __p A null pointer constant.
170 * @param __d A deleter.
171 * @param __a An allocator.
172 * @post use_count() == 1 && get() == __p
173 * @throw std::bad_alloc, in which case @a __d(__p) is called.
175 * Requirements: _Deleter's copy constructor and destructor must
176 * not throw _Alloc's copy constructor and destructor must not
179 * The last owner will call __d(__p)
181 template<typename _Deleter, typename _Alloc>
182 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
183 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
185 // Aliasing constructor
188 * @brief Constructs a %shared_ptr instance that stores @a __p
189 * and shares ownership with @a __r.
190 * @param __r A %shared_ptr.
191 * @param __p A pointer that will remain valid while @a *__r is valid.
192 * @post get() == __p && use_count() == __r.use_count()
194 * This can be used to construct a @c shared_ptr to a sub-object
195 * of an object managed by an existing @c shared_ptr.
198 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
199 * shared_ptr<int> pi(pii, &pii->first);
200 * assert(pii.use_count() == 2);
203 template<typename _Tp1>
204 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
205 : __shared_ptr<_Tp>(__r, __p) { }
208 * @brief If @a __r is empty, constructs an empty %shared_ptr;
209 * otherwise construct a %shared_ptr that shares ownership
211 * @param __r A %shared_ptr.
212 * @post get() == __r.get() && use_count() == __r.use_count()
214 template<typename _Tp1, typename = typename
215 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
216 shared_ptr(const shared_ptr<_Tp1>& __r)
217 : __shared_ptr<_Tp>(__r) { }
220 * @brief Move-constructs a %shared_ptr instance from @a __r.
221 * @param __r A %shared_ptr rvalue.
222 * @post *this contains the old value of @a __r, @a __r is empty.
224 shared_ptr(shared_ptr&& __r)
225 : __shared_ptr<_Tp>(std::move(__r)) { }
228 * @brief Move-constructs a %shared_ptr instance from @a __r.
229 * @param __r A %shared_ptr rvalue.
230 * @post *this contains the old value of @a __r, @a __r is empty.
232 template<typename _Tp1, typename = typename
233 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
234 shared_ptr(shared_ptr<_Tp1>&& __r)
235 : __shared_ptr<_Tp>(std::move(__r)) { }
238 * @brief Constructs a %shared_ptr that shares ownership with @a __r
239 * and stores a copy of the pointer stored in @a __r.
240 * @param __r A weak_ptr.
241 * @post use_count() == __r.use_count()
242 * @throw bad_weak_ptr when __r.expired(),
243 * in which case the constructor has no effect.
245 template<typename _Tp1>
246 explicit shared_ptr(const weak_ptr<_Tp1>& __r)
247 : __shared_ptr<_Tp>(__r) { }
249 #if _GLIBCXX_DEPRECATED
250 template<typename _Tp1>
251 shared_ptr(std::auto_ptr<_Tp1>&& __r)
252 : __shared_ptr<_Tp>(std::move(__r)) { }
255 template<typename _Tp1, typename _Del>
256 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
257 : __shared_ptr<_Tp>(std::move(__r)) { }
260 * @brief Construct an empty %shared_ptr.
261 * @param __p A null pointer constant.
262 * @post use_count() == 0 && get() == nullptr
264 constexpr shared_ptr(nullptr_t __p)
265 : __shared_ptr<_Tp>(__p) { }
267 template<typename _Tp1>
269 operator=(const shared_ptr<_Tp1>& __r) // never throws
271 this->__shared_ptr<_Tp>::operator=(__r);
275 #if _GLIBCXX_DEPRECATED
276 template<typename _Tp1>
278 operator=(std::auto_ptr<_Tp1>&& __r)
280 this->__shared_ptr<_Tp>::operator=(std::move(__r));
286 operator=(shared_ptr&& __r)
288 this->__shared_ptr<_Tp>::operator=(std::move(__r));
294 operator=(shared_ptr<_Tp1>&& __r)
296 this->__shared_ptr<_Tp>::operator=(std::move(__r));
300 template<typename _Tp1, typename _Del>
302 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
304 this->__shared_ptr<_Tp>::operator=(std::move(__r));
309 // This constructor is non-standard, it is used by allocate_shared.
310 template<typename _Alloc, typename... _Args>
311 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
313 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
316 template<typename _Tp1, typename _Alloc, typename... _Args>
317 friend shared_ptr<_Tp1>
318 allocate_shared(const _Alloc& __a, _Args&&... __args);
321 // 20.8.13.2.7 shared_ptr comparisons
322 template<typename _Tp1, typename _Tp2>
324 operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
325 { return __a.get() == __b.get(); }
327 template<typename _Tp>
329 operator==(const shared_ptr<_Tp>& __a, nullptr_t)
330 { return __a.get() == nullptr; }
332 template<typename _Tp>
334 operator==(nullptr_t, const shared_ptr<_Tp>& __b)
335 { return nullptr == __b.get(); }
337 template<typename _Tp1, typename _Tp2>
339 operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
340 { return __a.get() != __b.get(); }
342 template<typename _Tp>
344 operator!=(const shared_ptr<_Tp>& __a, nullptr_t)
345 { return __a.get() != nullptr; }
347 template<typename _Tp>
349 operator!=(nullptr_t, const shared_ptr<_Tp>& __b)
350 { return nullptr != __b.get(); }
352 template<typename _Tp1, typename _Tp2>
354 operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
355 { return __a.get() < __b.get(); }
357 template<typename _Tp>
358 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
361 // 20.8.13.2.9 shared_ptr specialized algorithms.
362 template<typename _Tp>
364 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
367 // 20.8.13.2.10 shared_ptr casts.
368 template<typename _Tp, typename _Tp1>
369 inline shared_ptr<_Tp>
370 static_pointer_cast(const shared_ptr<_Tp1>& __r)
371 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
373 template<typename _Tp, typename _Tp1>
374 inline shared_ptr<_Tp>
375 const_pointer_cast(const shared_ptr<_Tp1>& __r)
376 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
378 template<typename _Tp, typename _Tp1>
379 inline shared_ptr<_Tp>
380 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
382 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
383 return shared_ptr<_Tp>(__r, __p);
384 return shared_ptr<_Tp>();
389 * @brief A smart pointer with weak semantics.
391 * With forwarding constructors and assignment operators.
393 template<typename _Tp>
394 class weak_ptr : public __weak_ptr<_Tp>
398 : __weak_ptr<_Tp>() { }
400 template<typename _Tp1, typename = typename
401 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
402 weak_ptr(const weak_ptr<_Tp1>& __r)
403 : __weak_ptr<_Tp>(__r) { }
405 template<typename _Tp1, typename = typename
406 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
407 weak_ptr(const shared_ptr<_Tp1>& __r)
408 : __weak_ptr<_Tp>(__r) { }
410 template<typename _Tp1>
412 operator=(const weak_ptr<_Tp1>& __r) // never throws
414 this->__weak_ptr<_Tp>::operator=(__r);
418 template<typename _Tp1>
420 operator=(const shared_ptr<_Tp1>& __r) // never throws
422 this->__weak_ptr<_Tp>::operator=(__r);
427 lock() const // never throws
431 return shared_ptr<_Tp>();
435 return shared_ptr<_Tp>(*this);
437 __catch(const bad_weak_ptr&)
439 return shared_ptr<_Tp>();
442 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
447 // 20.8.13.3.7 weak_ptr specialized algorithms.
448 template<typename _Tp>
450 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
454 /// Primary template owner_less
455 template<typename _Tp>
458 /// Partial specialization of owner_less for shared_ptr.
459 template<typename _Tp>
460 struct owner_less<shared_ptr<_Tp>>
461 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
464 /// Partial specialization of owner_less for weak_ptr.
465 template<typename _Tp>
466 struct owner_less<weak_ptr<_Tp>>
467 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
471 * @brief Base class allowing use of member function shared_from_this.
473 template<typename _Tp>
474 class enable_shared_from_this
477 constexpr enable_shared_from_this() { }
479 enable_shared_from_this(const enable_shared_from_this&) { }
481 enable_shared_from_this&
482 operator=(const enable_shared_from_this&)
485 ~enable_shared_from_this() { }
490 { return shared_ptr<_Tp>(this->_M_weak_this); }
492 shared_ptr<const _Tp>
493 shared_from_this() const
494 { return shared_ptr<const _Tp>(this->_M_weak_this); }
497 template<typename _Tp1>
499 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
500 { _M_weak_this._M_assign(__p, __n); }
502 template<typename _Tp1>
504 __enable_shared_from_this_helper(const __shared_count<>& __pn,
505 const enable_shared_from_this* __pe,
509 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
512 mutable weak_ptr<_Tp> _M_weak_this;
516 * @brief Create an object that is owned by a shared_ptr.
517 * @param __a An allocator.
518 * @param __args Arguments for the @a _Tp object's constructor.
519 * @return A shared_ptr that owns the newly created object.
520 * @throw An exception thrown from @a _Alloc::allocate or from the
521 * constructor of @a _Tp.
523 * A copy of @a __a will be used to allocate memory for the shared_ptr
524 * and the new object.
526 template<typename _Tp, typename _Alloc, typename... _Args>
527 inline shared_ptr<_Tp>
528 allocate_shared(const _Alloc& __a, _Args&&... __args)
530 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
531 std::forward<_Args>(__args)...);
535 * @brief Create an object that is owned by a shared_ptr.
536 * @param __args Arguments for the @a _Tp object's constructor.
537 * @return A shared_ptr that owns the newly created object.
538 * @throw std::bad_alloc, or an exception thrown from the
539 * constructor of @a _Tp.
541 template<typename _Tp, typename... _Args>
542 inline shared_ptr<_Tp>
543 make_shared(_Args&&... __args)
545 typedef typename std::remove_const<_Tp>::type _Tp_nc;
546 return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
547 std::forward<_Args>(__args)...);
550 /// std::hash specialization for shared_ptr.
551 template<typename _Tp>
552 struct hash<shared_ptr<_Tp>>
553 : public std::unary_function<shared_ptr<_Tp>, size_t>
556 operator()(const shared_ptr<_Tp>& __s) const
557 { return std::hash<_Tp*>()(__s.get()); }
560 // @} group pointer_abstractions
562 _GLIBCXX_END_NAMESPACE_VERSION
565 #endif // _SHARED_PTR_H