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 * You should not attempt to use it directly.
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 shared_ptr() : __shared_ptr
<_Tp
>() { }
101 * @brief Construct a %shared_ptr that owns the pointer @a __p.
102 * @param __p A pointer that is convertible to element_type*.
103 * @post use_count() == 1 && get() == __p
104 * @throw std::bad_alloc, in which case @c delete @a __p is called.
106 template<typename _Tp1
>
107 explicit shared_ptr(_Tp1
* __p
) : __shared_ptr
<_Tp
>(__p
) { }
110 * @brief Construct a %shared_ptr that owns the pointer @a __p
111 * and the deleter @a __d.
112 * @param __p A pointer.
113 * @param __d A deleter.
114 * @post use_count() == 1 && get() == __p
115 * @throw std::bad_alloc, in which case @a __d(__p) is called.
117 * Requirements: _Deleter's copy constructor and destructor must
120 * __shared_ptr will release __p by calling __d(__p)
122 template<typename _Tp1
, typename _Deleter
>
123 shared_ptr(_Tp1
* __p
, _Deleter __d
) : __shared_ptr
<_Tp
>(__p
, __d
) { }
126 * @brief Construct a %shared_ptr that owns a null pointer
127 * and the deleter @a __d.
128 * @param __p A null pointer constant.
129 * @param __d A deleter.
130 * @post use_count() == 1 && get() == __p
131 * @throw std::bad_alloc, in which case @a __d(__p) is called.
133 * Requirements: _Deleter's copy constructor and destructor must
136 * The last owner will call __d(__p)
138 template<typename _Deleter
>
139 shared_ptr(nullptr_t __p
, _Deleter __d
)
140 : __shared_ptr
<_Tp
>(__p
, __d
) { }
143 * @brief Construct a %shared_ptr that owns the pointer @a __p
144 * and the deleter @a __d.
145 * @param __p A pointer.
146 * @param __d A deleter.
147 * @param __a An allocator.
148 * @post use_count() == 1 && get() == __p
149 * @throw std::bad_alloc, in which case @a __d(__p) is called.
151 * Requirements: _Deleter's copy constructor and destructor must
152 * not throw _Alloc's copy constructor and destructor must not
155 * __shared_ptr will release __p by calling __d(__p)
157 template<typename _Tp1
, typename _Deleter
, typename _Alloc
>
158 shared_ptr(_Tp1
* __p
, _Deleter __d
, const _Alloc
& __a
)
159 : __shared_ptr
<_Tp
>(__p
, __d
, __a
) { }
162 * @brief Construct a %shared_ptr that owns a null pointer
163 * and the deleter @a __d.
164 * @param __p A null pointer constant.
165 * @param __d A deleter.
166 * @param __a An allocator.
167 * @post use_count() == 1 && get() == __p
168 * @throw std::bad_alloc, in which case @a __d(__p) is called.
170 * Requirements: _Deleter's copy constructor and destructor must
171 * not throw _Alloc's copy constructor and destructor must not
174 * The last owner will call __d(__p)
176 template<typename _Deleter
, typename _Alloc
>
177 shared_ptr(nullptr_t __p
, _Deleter __d
, const _Alloc
& __a
)
178 : __shared_ptr
<_Tp
>(__p
, __d
, __a
) { }
180 // Aliasing constructor
183 * @brief Constructs a %shared_ptr instance that stores @a __p
184 * and shares ownership with @a __r.
185 * @param __r A %shared_ptr.
186 * @param __p A pointer that will remain valid while @a *__r is valid.
187 * @post get() == __p && use_count() == __r.use_count()
189 * This can be used to construct a @c shared_ptr to a sub-object
190 * of an object managed by an existing @c shared_ptr.
193 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
194 * shared_ptr<int> pi(pii, &pii->first);
195 * assert(pii.use_count() == 2);
198 template<typename _Tp1
>
199 shared_ptr(const shared_ptr
<_Tp1
>& __r
, _Tp
* __p
)
200 : __shared_ptr
<_Tp
>(__r
, __p
) { }
203 * @brief If @a __r is empty, constructs an empty %shared_ptr;
204 * otherwise construct a %shared_ptr that shares ownership
206 * @param __r A %shared_ptr.
207 * @post get() == __r.get() && use_count() == __r.use_count()
209 template<typename _Tp1
, typename
= typename
210 std::enable_if
<std::is_convertible
<_Tp1
*, _Tp
*>::value
>::type
>
211 shared_ptr(const shared_ptr
<_Tp1
>& __r
)
212 : __shared_ptr
<_Tp
>(__r
) { }
215 * @brief Move-constructs a %shared_ptr instance from @a __r.
216 * @param __r A %shared_ptr rvalue.
217 * @post *this contains the old value of @a __r, @a __r is empty.
219 shared_ptr(shared_ptr
&& __r
)
220 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
223 * @brief Move-constructs a %shared_ptr instance from @a __r.
224 * @param __r A %shared_ptr rvalue.
225 * @post *this contains the old value of @a __r, @a __r is empty.
227 template<typename _Tp1
, typename
= typename
228 std::enable_if
<std::is_convertible
<_Tp1
*, _Tp
*>::value
>::type
>
229 shared_ptr(shared_ptr
<_Tp1
>&& __r
)
230 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
233 * @brief Constructs a %shared_ptr that shares ownership with @a __r
234 * and stores a copy of the pointer stored in @a __r.
235 * @param __r A weak_ptr.
236 * @post use_count() == __r.use_count()
237 * @throw bad_weak_ptr when __r.expired(),
238 * in which case the constructor has no effect.
240 template<typename _Tp1
>
241 explicit shared_ptr(const weak_ptr
<_Tp1
>& __r
)
242 : __shared_ptr
<_Tp
>(__r
) { }
244 #if _GLIBCXX_DEPRECATED
245 template<typename _Tp1
>
246 shared_ptr(std::auto_ptr
<_Tp1
>&& __r
)
247 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
250 template<typename _Tp1
, typename _Del
>
251 shared_ptr(std::unique_ptr
<_Tp1
, _Del
>&& __r
)
252 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
255 * @brief Construct an empty %shared_ptr.
256 * @param __p A null pointer constant.
257 * @post use_count() == 0 && get() == nullptr
259 shared_ptr(nullptr_t __p
) : __shared_ptr
<_Tp
>(__p
) { }
261 template<typename _Tp1
>
263 operator=(const shared_ptr
<_Tp1
>& __r
) // never throws
265 this->__shared_ptr
<_Tp
>::operator=(__r
);
269 #if _GLIBCXX_DEPRECATED
270 template<typename _Tp1
>
272 operator=(std::auto_ptr
<_Tp1
>&& __r
)
274 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
280 operator=(shared_ptr
&& __r
)
282 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
288 operator=(shared_ptr
<_Tp1
>&& __r
)
290 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
294 template<typename _Tp1
, typename _Del
>
296 operator=(std::unique_ptr
<_Tp1
, _Del
>&& __r
)
298 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
303 // This constructor is non-standard, it is used by allocate_shared.
304 template<typename _Alloc
, typename
... _Args
>
305 shared_ptr(_Sp_make_shared_tag __tag
, _Alloc __a
, _Args
&&... __args
)
306 : __shared_ptr
<_Tp
>(__tag
, __a
, std::forward
<_Args
>(__args
)...)
309 template<typename _Tp1
, typename _Alloc
, typename
... _Args
>
310 friend shared_ptr
<_Tp1
>
311 allocate_shared(_Alloc __a
, _Args
&&... __args
);
314 // 20.8.13.2.7 shared_ptr comparisons
315 template<typename _Tp1
, typename _Tp2
>
317 operator==(const shared_ptr
<_Tp1
>& __a
, const shared_ptr
<_Tp2
>& __b
)
318 { return __a
.get() == __b
.get(); }
320 template<typename _Tp
>
322 operator==(const shared_ptr
<_Tp
>& __a
, nullptr_t
)
323 { return __a
.get() == nullptr; }
325 template<typename _Tp
>
327 operator==(nullptr_t
, const shared_ptr
<_Tp
>& __b
)
328 { return nullptr == __b
.get(); }
330 template<typename _Tp1
, typename _Tp2
>
332 operator!=(const shared_ptr
<_Tp1
>& __a
, const shared_ptr
<_Tp2
>& __b
)
333 { return __a
.get() != __b
.get(); }
335 template<typename _Tp
>
337 operator!=(const shared_ptr
<_Tp
>& __a
, nullptr_t
)
338 { return __a
.get() != nullptr; }
340 template<typename _Tp
>
342 operator!=(nullptr_t
, const shared_ptr
<_Tp
>& __b
)
343 { return nullptr != __b
.get(); }
345 template<typename _Tp1
, typename _Tp2
>
347 operator<(const shared_ptr
<_Tp1
>& __a
, const shared_ptr
<_Tp2
>& __b
)
348 { return __a
.get() < __b
.get(); }
350 template<typename _Tp
>
351 struct less
<shared_ptr
<_Tp
>> : public _Sp_less
<shared_ptr
<_Tp
>>
354 // 20.8.13.2.9 shared_ptr specialized algorithms.
355 template<typename _Tp
>
357 swap(shared_ptr
<_Tp
>& __a
, shared_ptr
<_Tp
>& __b
)
360 // 20.8.13.2.10 shared_ptr casts.
361 template<typename _Tp
, typename _Tp1
>
362 inline shared_ptr
<_Tp
>
363 static_pointer_cast(const shared_ptr
<_Tp1
>& __r
)
364 { return shared_ptr
<_Tp
>(__r
, static_cast<_Tp
*>(__r
.get())); }
366 template<typename _Tp
, typename _Tp1
>
367 inline shared_ptr
<_Tp
>
368 const_pointer_cast(const shared_ptr
<_Tp1
>& __r
)
369 { return shared_ptr
<_Tp
>(__r
, const_cast<_Tp
*>(__r
.get())); }
371 template<typename _Tp
, typename _Tp1
>
372 inline shared_ptr
<_Tp
>
373 dynamic_pointer_cast(const shared_ptr
<_Tp1
>& __r
)
375 if (_Tp
* __p
= dynamic_cast<_Tp
*>(__r
.get()))
376 return shared_ptr
<_Tp
>(__r
, __p
);
377 return shared_ptr
<_Tp
>();
382 * @brief A smart pointer with weak semantics.
384 * With forwarding constructors and assignment operators.
386 template<typename _Tp
>
387 class weak_ptr
: public __weak_ptr
<_Tp
>
390 weak_ptr() : __weak_ptr
<_Tp
>() { }
392 template<typename _Tp1
, typename
= typename
393 std::enable_if
<std::is_convertible
<_Tp1
*, _Tp
*>::value
>::type
>
394 weak_ptr(const weak_ptr
<_Tp1
>& __r
)
395 : __weak_ptr
<_Tp
>(__r
) { }
397 template<typename _Tp1
, typename
= typename
398 std::enable_if
<std::is_convertible
<_Tp1
*, _Tp
*>::value
>::type
>
399 weak_ptr(const shared_ptr
<_Tp1
>& __r
)
400 : __weak_ptr
<_Tp
>(__r
) { }
402 template<typename _Tp1
>
404 operator=(const weak_ptr
<_Tp1
>& __r
) // never throws
406 this->__weak_ptr
<_Tp
>::operator=(__r
);
410 template<typename _Tp1
>
412 operator=(const shared_ptr
<_Tp1
>& __r
) // never throws
414 this->__weak_ptr
<_Tp
>::operator=(__r
);
419 lock() const // never throws
423 return shared_ptr
<_Tp
>();
427 return shared_ptr
<_Tp
>(*this);
429 __catch(const bad_weak_ptr
&)
431 return shared_ptr
<_Tp
>();
434 return this->expired() ? shared_ptr
<_Tp
>() : shared_ptr
<_Tp
>(*this);
439 // 20.8.13.3.7 weak_ptr specialized algorithms.
440 template<typename _Tp
>
442 swap(weak_ptr
<_Tp
>& __a
, weak_ptr
<_Tp
>& __b
)
446 /// Primary template owner_less
447 template<typename _Tp
>
450 /// Partial specialization of owner_less for shared_ptr.
451 template<typename _Tp
>
452 struct owner_less
<shared_ptr
<_Tp
>>
453 : public _Sp_owner_less
<shared_ptr
<_Tp
>, weak_ptr
<_Tp
>>
456 /// Partial specialization of owner_less for weak_ptr.
457 template<typename _Tp
>
458 struct owner_less
<weak_ptr
<_Tp
>>
459 : public _Sp_owner_less
<weak_ptr
<_Tp
>, shared_ptr
<_Tp
>>
463 * @brief Base class allowing use of member function shared_from_this.
465 template<typename _Tp
>
466 class enable_shared_from_this
469 enable_shared_from_this() { }
471 enable_shared_from_this(const enable_shared_from_this
&) { }
473 enable_shared_from_this
&
474 operator=(const enable_shared_from_this
&)
477 ~enable_shared_from_this() { }
482 { return shared_ptr
<_Tp
>(this->_M_weak_this
); }
484 shared_ptr
<const _Tp
>
485 shared_from_this() const
486 { return shared_ptr
<const _Tp
>(this->_M_weak_this
); }
489 template<typename _Tp1
>
491 _M_weak_assign(_Tp1
* __p
, const __shared_count
<>& __n
) const
492 { _M_weak_this
._M_assign(__p
, __n
); }
494 template<typename _Tp1
>
496 __enable_shared_from_this_helper(const __shared_count
<>& __pn
,
497 const enable_shared_from_this
* __pe
,
501 __pe
->_M_weak_assign(const_cast<_Tp1
*>(__px
), __pn
);
504 mutable weak_ptr
<_Tp
> _M_weak_this
;
508 * @brief Create an object that is owned by a shared_ptr.
509 * @param __a An allocator.
510 * @param __args Arguments for the @a _Tp object's constructor.
511 * @return A shared_ptr that owns the newly created object.
512 * @throw An exception thrown from @a _Alloc::allocate or from the
513 * constructor of @a _Tp.
515 * A copy of @a __a will be used to allocate memory for the shared_ptr
516 * and the new object.
518 template<typename _Tp
, typename _Alloc
, typename
... _Args
>
519 inline shared_ptr
<_Tp
>
520 allocate_shared(_Alloc __a
, _Args
&&... __args
)
522 return shared_ptr
<_Tp
>(_Sp_make_shared_tag(), std::forward
<_Alloc
>(__a
),
523 std::forward
<_Args
>(__args
)...);
527 * @brief Create an object that is owned by a shared_ptr.
528 * @param __args Arguments for the @a _Tp object's constructor.
529 * @return A shared_ptr that owns the newly created object.
530 * @throw std::bad_alloc, or an exception thrown from the
531 * constructor of @a _Tp.
533 template<typename _Tp
, typename
... _Args
>
534 inline shared_ptr
<_Tp
>
535 make_shared(_Args
&&... __args
)
537 typedef typename
std::remove_const
<_Tp
>::type _Tp_nc
;
538 return allocate_shared
<_Tp
>(std::allocator
<_Tp_nc
>(),
539 std::forward
<_Args
>(__args
)...);
542 /// std::hash specialization for shared_ptr.
543 template<typename _Tp
>
544 struct hash
<shared_ptr
<_Tp
>>
545 : public std::unary_function
<shared_ptr
<_Tp
>, size_t>
548 operator()(const shared_ptr
<_Tp
>& __s
) const
549 { return std::hash
<_Tp
*>()(__s
.get()); }
552 // @} group pointer_abstractions
554 _GLIBCXX_END_NAMESPACE
556 #endif // _SHARED_PTR_H