1 // shared_ptr and weak_ptr implementation -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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) noexcept
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() noexcept
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) noexcept
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) noexcept
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) noexcept
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) noexcept
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_USE_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) noexcept
265 : __shared_ptr<_Tp>(__p) { }
267 template<typename _Tp1>
269 operator=(const shared_ptr<_Tp1>& __r) noexcept
271 this->__shared_ptr<_Tp>::operator=(__r);
275 #if _GLIBCXX_USE_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) noexcept
288 this->__shared_ptr<_Tp>::operator=(std::move(__r));
294 operator=(shared_ptr<_Tp1>&& __r) noexcept
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,
325 const shared_ptr<_Tp2>& __b) noexcept
326 { return __a.get() == __b.get(); }
328 template<typename _Tp>
330 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
333 template<typename _Tp>
335 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
338 template<typename _Tp1, typename _Tp2>
340 operator!=(const shared_ptr<_Tp1>& __a,
341 const shared_ptr<_Tp2>& __b) noexcept
342 { return __a.get() != __b.get(); }
344 template<typename _Tp>
346 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
347 { return (bool)__a; }
349 template<typename _Tp>
351 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
352 { return (bool)__a; }
354 template<typename _Tp1, typename _Tp2>
356 operator<(const shared_ptr<_Tp1>& __a,
357 const shared_ptr<_Tp2>& __b) noexcept
359 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT;
360 return std::less<_CT>()(__a.get(), __b.get());
363 template<typename _Tp>
365 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
366 { return std::less<_Tp*>()(__a.get(), nullptr); }
368 template<typename _Tp>
370 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
371 { return std::less<_Tp*>()(nullptr, __a.get()); }
373 template<typename _Tp1, typename _Tp2>
375 operator<=(const shared_ptr<_Tp1>& __a,
376 const shared_ptr<_Tp2>& __b) noexcept
377 { return !(__b < __a); }
379 template<typename _Tp>
381 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
382 { return !(nullptr < __a); }
384 template<typename _Tp>
386 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
387 { return !(__a < nullptr); }
389 template<typename _Tp1, typename _Tp2>
391 operator>(const shared_ptr<_Tp1>& __a,
392 const shared_ptr<_Tp2>& __b) noexcept
393 { return (__b < __a); }
395 template<typename _Tp>
397 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
398 { return std::less<_Tp*>()(nullptr, __a.get()); }
400 template<typename _Tp>
402 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
403 { return std::less<_Tp*>()(__a.get(), nullptr); }
405 template<typename _Tp1, typename _Tp2>
407 operator>=(const shared_ptr<_Tp1>& __a,
408 const shared_ptr<_Tp2>& __b) noexcept
409 { return !(__a < __b); }
411 template<typename _Tp>
413 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
414 { return !(__a < nullptr); }
416 template<typename _Tp>
418 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
419 { return !(nullptr < __a); }
421 template<typename _Tp>
422 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
425 // 20.8.13.2.9 shared_ptr specialized algorithms.
426 template<typename _Tp>
428 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
431 // 20.8.13.2.10 shared_ptr casts.
432 template<typename _Tp, typename _Tp1>
433 inline shared_ptr<_Tp>
434 static_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
435 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
437 template<typename _Tp, typename _Tp1>
438 inline shared_ptr<_Tp>
439 const_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
440 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
442 template<typename _Tp, typename _Tp1>
443 inline shared_ptr<_Tp>
444 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
446 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
447 return shared_ptr<_Tp>(__r, __p);
448 return shared_ptr<_Tp>();
453 * @brief A smart pointer with weak semantics.
455 * With forwarding constructors and assignment operators.
457 template<typename _Tp>
458 class weak_ptr : public __weak_ptr<_Tp>
461 constexpr weak_ptr() noexcept
462 : __weak_ptr<_Tp>() { }
464 template<typename _Tp1, typename = typename
465 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
466 weak_ptr(const weak_ptr<_Tp1>& __r) noexcept
467 : __weak_ptr<_Tp>(__r) { }
469 template<typename _Tp1, typename = typename
470 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
471 weak_ptr(const shared_ptr<_Tp1>& __r) noexcept
472 : __weak_ptr<_Tp>(__r) { }
474 template<typename _Tp1>
476 operator=(const weak_ptr<_Tp1>& __r) noexcept
478 this->__weak_ptr<_Tp>::operator=(__r);
482 template<typename _Tp1>
484 operator=(const shared_ptr<_Tp1>& __r) noexcept
486 this->__weak_ptr<_Tp>::operator=(__r);
491 lock() const noexcept
495 return shared_ptr<_Tp>();
499 return shared_ptr<_Tp>(*this);
501 __catch(const bad_weak_ptr&)
503 return shared_ptr<_Tp>();
506 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
511 // 20.8.13.3.7 weak_ptr specialized algorithms.
512 template<typename _Tp>
514 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
518 /// Primary template owner_less
519 template<typename _Tp>
522 /// Partial specialization of owner_less for shared_ptr.
523 template<typename _Tp>
524 struct owner_less<shared_ptr<_Tp>>
525 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
528 /// Partial specialization of owner_less for weak_ptr.
529 template<typename _Tp>
530 struct owner_less<weak_ptr<_Tp>>
531 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
535 * @brief Base class allowing use of member function shared_from_this.
537 template<typename _Tp>
538 class enable_shared_from_this
541 constexpr enable_shared_from_this() noexcept { }
543 enable_shared_from_this(const enable_shared_from_this&) noexcept { }
545 enable_shared_from_this&
546 operator=(const enable_shared_from_this&) noexcept
549 ~enable_shared_from_this() { }
554 { return shared_ptr<_Tp>(this->_M_weak_this); }
556 shared_ptr<const _Tp>
557 shared_from_this() const
558 { return shared_ptr<const _Tp>(this->_M_weak_this); }
561 template<typename _Tp1>
563 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
564 { _M_weak_this._M_assign(__p, __n); }
566 template<typename _Tp1>
568 __enable_shared_from_this_helper(const __shared_count<>& __pn,
569 const enable_shared_from_this* __pe,
570 const _Tp1* __px) noexcept
573 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
576 mutable weak_ptr<_Tp> _M_weak_this;
580 * @brief Create an object that is owned by a shared_ptr.
581 * @param __a An allocator.
582 * @param __args Arguments for the @a _Tp object's constructor.
583 * @return A shared_ptr that owns the newly created object.
584 * @throw An exception thrown from @a _Alloc::allocate or from the
585 * constructor of @a _Tp.
587 * A copy of @a __a will be used to allocate memory for the shared_ptr
588 * and the new object.
590 template<typename _Tp, typename _Alloc, typename... _Args>
591 inline shared_ptr<_Tp>
592 allocate_shared(const _Alloc& __a, _Args&&... __args)
594 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
595 std::forward<_Args>(__args)...);
599 * @brief Create an object that is owned by a shared_ptr.
600 * @param __args Arguments for the @a _Tp object's constructor.
601 * @return A shared_ptr that owns the newly created object.
602 * @throw std::bad_alloc, or an exception thrown from the
603 * constructor of @a _Tp.
605 template<typename _Tp, typename... _Args>
606 inline shared_ptr<_Tp>
607 make_shared(_Args&&... __args)
609 typedef typename std::remove_const<_Tp>::type _Tp_nc;
610 return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
611 std::forward<_Args>(__args)...);
614 /// std::hash specialization for shared_ptr.
615 template<typename _Tp>
616 struct hash<shared_ptr<_Tp>>
617 : public std::unary_function<shared_ptr<_Tp>, size_t>
620 operator()(const shared_ptr<_Tp>& __s) const
621 { return std::hash<_Tp*>()(__s.get()); }
624 // @} group pointer_abstractions
626 _GLIBCXX_END_NAMESPACE_VERSION
629 #endif // _SHARED_PTR_H