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>() { }
103 shared_ptr(const shared_ptr&) noexcept = default;
106 * @brief Construct a %shared_ptr that owns the pointer @a __p.
107 * @param __p A pointer that is convertible to element_type*.
108 * @post use_count() == 1 && get() == __p
109 * @throw std::bad_alloc, in which case @c delete @a __p is called.
111 template<typename _Tp1>
112 explicit shared_ptr(_Tp1* __p)
113 : __shared_ptr<_Tp>(__p) { }
116 * @brief Construct a %shared_ptr that owns the pointer @a __p
117 * and the deleter @a __d.
118 * @param __p A pointer.
119 * @param __d A deleter.
120 * @post use_count() == 1 && get() == __p
121 * @throw std::bad_alloc, in which case @a __d(__p) is called.
123 * Requirements: _Deleter's copy constructor and destructor must
126 * __shared_ptr will release __p by calling __d(__p)
128 template<typename _Tp1, typename _Deleter>
129 shared_ptr(_Tp1* __p, _Deleter __d)
130 : __shared_ptr<_Tp>(__p, __d) { }
133 * @brief Construct a %shared_ptr that owns a null pointer
134 * and the deleter @a __d.
135 * @param __p A null pointer constant.
136 * @param __d A deleter.
137 * @post use_count() == 1 && get() == __p
138 * @throw std::bad_alloc, in which case @a __d(__p) is called.
140 * Requirements: _Deleter's copy constructor and destructor must
143 * The last owner will call __d(__p)
145 template<typename _Deleter>
146 shared_ptr(nullptr_t __p, _Deleter __d)
147 : __shared_ptr<_Tp>(__p, __d) { }
150 * @brief Construct a %shared_ptr that owns the pointer @a __p
151 * and the deleter @a __d.
152 * @param __p A pointer.
153 * @param __d A deleter.
154 * @param __a An allocator.
155 * @post use_count() == 1 && get() == __p
156 * @throw std::bad_alloc, in which case @a __d(__p) is called.
158 * Requirements: _Deleter's copy constructor and destructor must
159 * not throw _Alloc's copy constructor and destructor must not
162 * __shared_ptr will release __p by calling __d(__p)
164 template<typename _Tp1, typename _Deleter, typename _Alloc>
165 shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
166 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
169 * @brief Construct a %shared_ptr that owns a null pointer
170 * and the deleter @a __d.
171 * @param __p A null pointer constant.
172 * @param __d A deleter.
173 * @param __a An allocator.
174 * @post use_count() == 1 && get() == __p
175 * @throw std::bad_alloc, in which case @a __d(__p) is called.
177 * Requirements: _Deleter's copy constructor and destructor must
178 * not throw _Alloc's copy constructor and destructor must not
181 * The last owner will call __d(__p)
183 template<typename _Deleter, typename _Alloc>
184 shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
185 : __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
187 // Aliasing constructor
190 * @brief Constructs a %shared_ptr instance that stores @a __p
191 * and shares ownership with @a __r.
192 * @param __r A %shared_ptr.
193 * @param __p A pointer that will remain valid while @a *__r is valid.
194 * @post get() == __p && use_count() == __r.use_count()
196 * This can be used to construct a @c shared_ptr to a sub-object
197 * of an object managed by an existing @c shared_ptr.
200 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
201 * shared_ptr<int> pi(pii, &pii->first);
202 * assert(pii.use_count() == 2);
205 template<typename _Tp1>
206 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p) noexcept
207 : __shared_ptr<_Tp>(__r, __p) { }
210 * @brief If @a __r is empty, constructs an empty %shared_ptr;
211 * otherwise construct a %shared_ptr that shares ownership
213 * @param __r A %shared_ptr.
214 * @post get() == __r.get() && use_count() == __r.use_count()
216 template<typename _Tp1, typename = typename
217 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
218 shared_ptr(const shared_ptr<_Tp1>& __r) noexcept
219 : __shared_ptr<_Tp>(__r) { }
222 * @brief Move-constructs a %shared_ptr instance from @a __r.
223 * @param __r A %shared_ptr rvalue.
224 * @post *this contains the old value of @a __r, @a __r is empty.
226 shared_ptr(shared_ptr&& __r) noexcept
227 : __shared_ptr<_Tp>(std::move(__r)) { }
230 * @brief Move-constructs a %shared_ptr instance from @a __r.
231 * @param __r A %shared_ptr rvalue.
232 * @post *this contains the old value of @a __r, @a __r is empty.
234 template<typename _Tp1, typename = typename
235 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
236 shared_ptr(shared_ptr<_Tp1>&& __r) noexcept
237 : __shared_ptr<_Tp>(std::move(__r)) { }
240 * @brief Constructs a %shared_ptr that shares ownership with @a __r
241 * and stores a copy of the pointer stored in @a __r.
242 * @param __r A weak_ptr.
243 * @post use_count() == __r.use_count()
244 * @throw bad_weak_ptr when __r.expired(),
245 * in which case the constructor has no effect.
247 template<typename _Tp1>
248 explicit shared_ptr(const weak_ptr<_Tp1>& __r)
249 : __shared_ptr<_Tp>(__r) { }
251 #if _GLIBCXX_USE_DEPRECATED
252 template<typename _Tp1>
253 shared_ptr(std::auto_ptr<_Tp1>&& __r)
254 : __shared_ptr<_Tp>(std::move(__r)) { }
257 template<typename _Tp1, typename _Del>
258 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
259 : __shared_ptr<_Tp>(std::move(__r)) { }
262 * @brief Construct an empty %shared_ptr.
263 * @param __p A null pointer constant.
264 * @post use_count() == 0 && get() == nullptr
266 constexpr shared_ptr(nullptr_t __p) noexcept
267 : __shared_ptr<_Tp>(__p) { }
269 shared_ptr& operator=(const shared_ptr&) noexcept = default;
271 template<typename _Tp1>
273 operator=(const shared_ptr<_Tp1>& __r) noexcept
275 this->__shared_ptr<_Tp>::operator=(__r);
279 #if _GLIBCXX_USE_DEPRECATED
280 template<typename _Tp1>
282 operator=(std::auto_ptr<_Tp1>&& __r)
284 this->__shared_ptr<_Tp>::operator=(std::move(__r));
290 operator=(shared_ptr&& __r) noexcept
292 this->__shared_ptr<_Tp>::operator=(std::move(__r));
298 operator=(shared_ptr<_Tp1>&& __r) noexcept
300 this->__shared_ptr<_Tp>::operator=(std::move(__r));
304 template<typename _Tp1, typename _Del>
306 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
308 this->__shared_ptr<_Tp>::operator=(std::move(__r));
313 // This constructor is non-standard, it is used by allocate_shared.
314 template<typename _Alloc, typename... _Args>
315 shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
317 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
320 template<typename _Tp1, typename _Alloc, typename... _Args>
321 friend shared_ptr<_Tp1>
322 allocate_shared(const _Alloc& __a, _Args&&... __args);
325 // 20.8.13.2.7 shared_ptr comparisons
326 template<typename _Tp1, typename _Tp2>
328 operator==(const shared_ptr<_Tp1>& __a,
329 const shared_ptr<_Tp2>& __b) noexcept
330 { return __a.get() == __b.get(); }
332 template<typename _Tp>
334 operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
337 template<typename _Tp>
339 operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
342 template<typename _Tp1, typename _Tp2>
344 operator!=(const shared_ptr<_Tp1>& __a,
345 const shared_ptr<_Tp2>& __b) noexcept
346 { return __a.get() != __b.get(); }
348 template<typename _Tp>
350 operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
351 { return (bool)__a; }
353 template<typename _Tp>
355 operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
356 { return (bool)__a; }
358 template<typename _Tp1, typename _Tp2>
360 operator<(const shared_ptr<_Tp1>& __a,
361 const shared_ptr<_Tp2>& __b) noexcept
363 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT;
364 return std::less<_CT>()(__a.get(), __b.get());
367 template<typename _Tp>
369 operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
370 { return std::less<_Tp*>()(__a.get(), nullptr); }
372 template<typename _Tp>
374 operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
375 { return std::less<_Tp*>()(nullptr, __a.get()); }
377 template<typename _Tp1, typename _Tp2>
379 operator<=(const shared_ptr<_Tp1>& __a,
380 const shared_ptr<_Tp2>& __b) noexcept
381 { return !(__b < __a); }
383 template<typename _Tp>
385 operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
386 { return !(nullptr < __a); }
388 template<typename _Tp>
390 operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
391 { return !(__a < nullptr); }
393 template<typename _Tp1, typename _Tp2>
395 operator>(const shared_ptr<_Tp1>& __a,
396 const shared_ptr<_Tp2>& __b) noexcept
397 { return (__b < __a); }
399 template<typename _Tp>
401 operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
402 { return std::less<_Tp*>()(nullptr, __a.get()); }
404 template<typename _Tp>
406 operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
407 { return std::less<_Tp*>()(__a.get(), nullptr); }
409 template<typename _Tp1, typename _Tp2>
411 operator>=(const shared_ptr<_Tp1>& __a,
412 const shared_ptr<_Tp2>& __b) noexcept
413 { return !(__a < __b); }
415 template<typename _Tp>
417 operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
418 { return !(__a < nullptr); }
420 template<typename _Tp>
422 operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
423 { return !(nullptr < __a); }
425 template<typename _Tp>
426 struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
429 // 20.8.13.2.9 shared_ptr specialized algorithms.
430 template<typename _Tp>
432 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
435 // 20.8.13.2.10 shared_ptr casts.
436 template<typename _Tp, typename _Tp1>
437 inline shared_ptr<_Tp>
438 static_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
439 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
441 template<typename _Tp, typename _Tp1>
442 inline shared_ptr<_Tp>
443 const_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
444 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
446 template<typename _Tp, typename _Tp1>
447 inline shared_ptr<_Tp>
448 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) noexcept
450 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
451 return shared_ptr<_Tp>(__r, __p);
452 return shared_ptr<_Tp>();
457 * @brief A smart pointer with weak semantics.
459 * With forwarding constructors and assignment operators.
461 template<typename _Tp>
462 class weak_ptr : public __weak_ptr<_Tp>
465 constexpr weak_ptr() noexcept
466 : __weak_ptr<_Tp>() { }
468 template<typename _Tp1, typename = typename
469 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
470 weak_ptr(const weak_ptr<_Tp1>& __r) noexcept
471 : __weak_ptr<_Tp>(__r) { }
473 template<typename _Tp1, typename = typename
474 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
475 weak_ptr(const shared_ptr<_Tp1>& __r) noexcept
476 : __weak_ptr<_Tp>(__r) { }
478 template<typename _Tp1>
480 operator=(const weak_ptr<_Tp1>& __r) noexcept
482 this->__weak_ptr<_Tp>::operator=(__r);
486 template<typename _Tp1>
488 operator=(const shared_ptr<_Tp1>& __r) noexcept
490 this->__weak_ptr<_Tp>::operator=(__r);
495 lock() const noexcept
499 return shared_ptr<_Tp>();
503 return shared_ptr<_Tp>(*this);
505 __catch(const bad_weak_ptr&)
507 return shared_ptr<_Tp>();
510 return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
515 // 20.8.13.3.7 weak_ptr specialized algorithms.
516 template<typename _Tp>
518 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
522 /// Primary template owner_less
523 template<typename _Tp>
526 /// Partial specialization of owner_less for shared_ptr.
527 template<typename _Tp>
528 struct owner_less<shared_ptr<_Tp>>
529 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
532 /// Partial specialization of owner_less for weak_ptr.
533 template<typename _Tp>
534 struct owner_less<weak_ptr<_Tp>>
535 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
539 * @brief Base class allowing use of member function shared_from_this.
541 template<typename _Tp>
542 class enable_shared_from_this
545 constexpr enable_shared_from_this() noexcept { }
547 enable_shared_from_this(const enable_shared_from_this&) noexcept { }
549 enable_shared_from_this&
550 operator=(const enable_shared_from_this&) noexcept
553 ~enable_shared_from_this() { }
558 { return shared_ptr<_Tp>(this->_M_weak_this); }
560 shared_ptr<const _Tp>
561 shared_from_this() const
562 { return shared_ptr<const _Tp>(this->_M_weak_this); }
565 template<typename _Tp1>
567 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
568 { _M_weak_this._M_assign(__p, __n); }
570 template<typename _Tp1>
572 __enable_shared_from_this_helper(const __shared_count<>& __pn,
573 const enable_shared_from_this* __pe,
574 const _Tp1* __px) noexcept
577 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
580 mutable weak_ptr<_Tp> _M_weak_this;
584 * @brief Create an object that is owned by a shared_ptr.
585 * @param __a An allocator.
586 * @param __args Arguments for the @a _Tp object's constructor.
587 * @return A shared_ptr that owns the newly created object.
588 * @throw An exception thrown from @a _Alloc::allocate or from the
589 * constructor of @a _Tp.
591 * A copy of @a __a will be used to allocate memory for the shared_ptr
592 * and the new object.
594 template<typename _Tp, typename _Alloc, typename... _Args>
595 inline shared_ptr<_Tp>
596 allocate_shared(const _Alloc& __a, _Args&&... __args)
598 return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
599 std::forward<_Args>(__args)...);
603 * @brief Create an object that is owned by a shared_ptr.
604 * @param __args Arguments for the @a _Tp object's constructor.
605 * @return A shared_ptr that owns the newly created object.
606 * @throw std::bad_alloc, or an exception thrown from the
607 * constructor of @a _Tp.
609 template<typename _Tp, typename... _Args>
610 inline shared_ptr<_Tp>
611 make_shared(_Args&&... __args)
613 typedef typename std::remove_const<_Tp>::type _Tp_nc;
614 return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
615 std::forward<_Args>(__args)...);
618 /// std::hash specialization for shared_ptr.
619 template<typename _Tp>
620 struct hash<shared_ptr<_Tp>>
621 : public __hash_base<size_t, shared_ptr<_Tp>>
624 operator()(const shared_ptr<_Tp>& __s) const noexcept
625 { return std::hash<_Tp*>()(__s.get()); }
628 // @} group pointer_abstractions
630 _GLIBCXX_END_NAMESPACE_VERSION
633 #endif // _SHARED_PTR_H