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 the pointer @a __p
127 * and the deleter @a __d.
128 * @param __p A pointer.
129 * @param __d A deleter.
130 * @param __a An allocator.
131 * @post use_count() == 1 && get() == __p
132 * @throw std::bad_alloc, in which case @a __d(__p) is called.
134 * Requirements: _Deleter's copy constructor and destructor must
135 * not throw _Alloc's copy constructor and destructor must not
138 * __shared_ptr will release __p by calling __d(__p)
140 template<typename _Tp1, typename _Deleter, typename _Alloc>
141 shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
142 : __shared_ptr<_Tp>(__p, __d, __a) { }
144 // Aliasing constructor
147 * @brief Constructs a %shared_ptr instance that stores @a __p
148 * and shares ownership with @a __r.
149 * @param __r A %shared_ptr.
150 * @param __p A pointer that will remain valid while @a *__r is valid.
151 * @post get() == __p && use_count() == __r.use_count()
153 * This can be used to construct a @c shared_ptr to a sub-object
154 * of an object managed by an existing @c shared_ptr.
157 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
158 * shared_ptr<int> pi(pii, &pii->first);
159 * assert(pii.use_count() == 2);
162 template<typename _Tp1>
163 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
164 : __shared_ptr<_Tp>(__r, __p) { }
167 * @brief If @a __r is empty, constructs an empty %shared_ptr;
168 * otherwise construct a %shared_ptr that shares ownership
170 * @param __r A %shared_ptr.
171 * @post get() == __r.get() && use_count() == __r.use_count()
173 template<typename _Tp1>
174 shared_ptr(const shared_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { }
177 * @brief Move-constructs a %shared_ptr instance from @a __r.
178 * @param __r A %shared_ptr rvalue.
179 * @post *this contains the old value of @a __r, @a __r is empty.
181 shared_ptr(shared_ptr&& __r)
182 : __shared_ptr<_Tp>(std::move(__r)) { }
185 * @brief Move-constructs a %shared_ptr instance from @a __r.
186 * @param __r A %shared_ptr rvalue.
187 * @post *this contains the old value of @a __r, @a __r is empty.
189 template<typename _Tp1>
190 shared_ptr(shared_ptr<_Tp1>&& __r)
191 : __shared_ptr<_Tp>(std::move(__r)) { }
194 * @brief Constructs a %shared_ptr that shares ownership with @a __r
195 * and stores a copy of the pointer stored in @a __r.
196 * @param __r A weak_ptr.
197 * @post use_count() == __r.use_count()
198 * @throw bad_weak_ptr when __r.expired(),
199 * in which case the constructor has no effect.
201 template<typename _Tp1>
202 explicit shared_ptr(const weak_ptr<_Tp1>& __r)
203 : __shared_ptr<_Tp>(__r) { }
205 #if _GLIBCXX_DEPRECATED
206 template<typename _Tp1>
207 shared_ptr(std::auto_ptr<_Tp1>&& __r)
208 : __shared_ptr<_Tp>(std::move(__r)) { }
211 template<typename _Tp1, typename _Del>
212 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
213 : __shared_ptr<_Tp>(std::move(__r)) { }
215 template<typename _Tp1>
217 operator=(const shared_ptr<_Tp1>& __r) // never throws
219 this->__shared_ptr<_Tp>::operator=(__r);
223 #if _GLIBCXX_DEPRECATED
224 template<typename _Tp1>
226 operator=(std::auto_ptr<_Tp1>&& __r)
228 this->__shared_ptr<_Tp>::operator=(std::move(__r));
234 operator=(shared_ptr&& __r)
236 this->__shared_ptr<_Tp>::operator=(std::move(__r));
242 operator=(shared_ptr<_Tp1>&& __r)
244 this->__shared_ptr<_Tp>::operator=(std::move(__r));
248 template<typename _Tp1, typename _Del>
250 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
252 this->__shared_ptr<_Tp>::operator=(std::move(__r));
257 // This constructor is non-standard, it is used by allocate_shared.
258 template<typename _Alloc, typename... _Args>
259 shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
260 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
263 template<typename _Tp1, typename _Alloc, typename... _Args>
264 friend shared_ptr<_Tp1>
265 allocate_shared(_Alloc __a, _Args&&... __args);
268 // 20.8.13.2.7 shared_ptr comparisons
269 template<typename _Tp1, typename _Tp2>
271 operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
272 { return __a.get() == __b.get(); }
274 template<typename _Tp1, typename _Tp2>
276 operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
277 { return __a.get() != __b.get(); }
279 template<typename _Tp1, typename _Tp2>
281 operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
282 { return __a.get() < __b.get(); }
284 template<typename _Tp>
285 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
288 // 20.8.13.2.9 shared_ptr specialized algorithms.
289 template<typename _Tp>
291 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
294 // 20.8.13.2.10 shared_ptr casts.
295 template<typename _Tp, typename _Tp1>
296 inline shared_ptr<_Tp>
297 static_pointer_cast(const shared_ptr<_Tp1>& __r)
298 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
300 template<typename _Tp, typename _Tp1>
301 inline shared_ptr<_Tp>
302 const_pointer_cast(const shared_ptr<_Tp1>& __r)
303 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
305 template<typename _Tp, typename _Tp1>
306 inline shared_ptr<_Tp>
307 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
309 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
310 return shared_ptr<_Tp>(__r, __p);
311 return shared_ptr<_Tp>();
316 * @brief A smart pointer with weak semantics.
318 * With forwarding constructors and assignment operators.
320 template<typename _Tp>
321 class weak_ptr : public __weak_ptr<_Tp>
324 weak_ptr() : __weak_ptr<_Tp>() { }
326 template<typename _Tp1>
327 weak_ptr(const weak_ptr<_Tp1>& __r)
328 : __weak_ptr<_Tp>(__r) { }
330 template<typename _Tp1>
331 weak_ptr(const shared_ptr<_Tp1>& __r)
332 : __weak_ptr<_Tp>(__r) { }
334 template<typename _Tp1>
336 operator=(const weak_ptr<_Tp1>& __r) // never throws
338 this->__weak_ptr<_Tp>::operator=(__r);
342 template<typename _Tp1>
344 operator=(const shared_ptr<_Tp1>& __r) // never throws
346 this->__weak_ptr<_Tp>::operator=(__r);
351 lock() const // never throws
355 return shared_ptr<_Tp>();
359 return shared_ptr<_Tp>(*this);
361 __catch(const bad_weak_ptr&)
363 return shared_ptr<_Tp>();
366 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
371 // 20.8.13.3.7 weak_ptr specialized algorithms.
372 template<typename _Tp>
374 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
378 /// Primary template owner_less
379 template<typename _Tp>
382 /// Partial specialization of owner_less for shared_ptr.
383 template<typename _Tp>
384 struct owner_less<shared_ptr<_Tp>>
385 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
388 /// Partial specialization of owner_less for weak_ptr.
389 template<typename _Tp>
390 struct owner_less<weak_ptr<_Tp>>
391 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
395 * @brief Base class allowing use of member function shared_from_this.
397 template<typename _Tp>
398 class enable_shared_from_this
401 enable_shared_from_this() { }
403 enable_shared_from_this(const enable_shared_from_this&) { }
405 enable_shared_from_this&
406 operator=(const enable_shared_from_this&)
409 ~enable_shared_from_this() { }
414 { return shared_ptr<_Tp>(this->_M_weak_this); }
416 shared_ptr<const _Tp>
417 shared_from_this() const
418 { return shared_ptr<const _Tp>(this->_M_weak_this); }
421 template<typename _Tp1>
423 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
424 { _M_weak_this._M_assign(__p, __n); }
426 template<typename _Tp1>
428 __enable_shared_from_this_helper(const __shared_count<>& __pn,
429 const enable_shared_from_this* __pe,
433 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
436 mutable weak_ptr<_Tp> _M_weak_this;
440 * @brief Create an object that is owned by a shared_ptr.
441 * @param __a An allocator.
442 * @param __args Arguments for the @a _Tp object's constructor.
443 * @return A shared_ptr that owns the newly created object.
444 * @throw An exception thrown from @a _Alloc::allocate or from the
445 * constructor of @a _Tp.
447 * A copy of @a __a will be used to allocate memory for the shared_ptr
448 * and the new object.
450 template<typename _Tp, typename _Alloc, typename... _Args>
451 inline shared_ptr<_Tp>
452 allocate_shared(_Alloc __a, _Args&&... __args)
454 return shared_ptr<_Tp>(_Sp_make_shared_tag(), std::forward<_Alloc>(__a),
455 std::forward<_Args>(__args)...);
459 * @brief Create an object that is owned by a shared_ptr.
460 * @param __args Arguments for the @a _Tp object's constructor.
461 * @return A shared_ptr that owns the newly created object.
462 * @throw std::bad_alloc, or an exception thrown from the
463 * constructor of @a _Tp.
465 template<typename _Tp, typename... _Args>
466 inline shared_ptr<_Tp>
467 make_shared(_Args&&... __args)
469 typedef typename std::remove_const<_Tp>::type _Tp_nc;
470 return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
471 std::forward<_Args>(__args)...);
474 // @} group pointer_abstractions
476 _GLIBCXX_END_NAMESPACE
478 #endif // _SHARED_PTR_H