1 // shared_ptr and weak_ptr implementation -*- C++ -*-
3 // Copyright (C) 2007-2016 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)
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 /// 20.7.2.2.11 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 /// 20.7.2.2.10 shared_ptr get_deleter
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
>
95 template<typename _Ptr
>
97 = typename enable_if
<is_convertible
<_Ptr
, _Tp
*>::value
>::type
;
101 * @brief Construct an empty %shared_ptr.
102 * @post use_count()==0 && get()==0
104 constexpr shared_ptr() noexcept
105 : __shared_ptr
<_Tp
>() { }
107 shared_ptr(const shared_ptr
&) noexcept
= default;
110 * @brief Construct a %shared_ptr that owns the pointer @a __p.
111 * @param __p A pointer that is convertible to element_type*.
112 * @post use_count() == 1 && get() == __p
113 * @throw std::bad_alloc, in which case @c delete @a __p is called.
115 template<typename _Tp1
>
116 explicit shared_ptr(_Tp1
* __p
)
117 : __shared_ptr
<_Tp
>(__p
) { }
120 * @brief Construct a %shared_ptr that owns the pointer @a __p
121 * and the deleter @a __d.
122 * @param __p A pointer.
123 * @param __d A deleter.
124 * @post use_count() == 1 && get() == __p
125 * @throw std::bad_alloc, in which case @a __d(__p) is called.
127 * Requirements: _Deleter's copy constructor and destructor must
130 * __shared_ptr will release __p by calling __d(__p)
132 template<typename _Tp1
, typename _Deleter
>
133 shared_ptr(_Tp1
* __p
, _Deleter __d
)
134 : __shared_ptr
<_Tp
>(__p
, __d
) { }
137 * @brief Construct a %shared_ptr that owns a null pointer
138 * and the deleter @a __d.
139 * @param __p A null pointer constant.
140 * @param __d A deleter.
141 * @post use_count() == 1 && get() == __p
142 * @throw std::bad_alloc, in which case @a __d(__p) is called.
144 * Requirements: _Deleter's copy constructor and destructor must
147 * The last owner will call __d(__p)
149 template<typename _Deleter
>
150 shared_ptr(nullptr_t __p
, _Deleter __d
)
151 : __shared_ptr
<_Tp
>(__p
, __d
) { }
154 * @brief Construct a %shared_ptr that owns the pointer @a __p
155 * and the deleter @a __d.
156 * @param __p A pointer.
157 * @param __d A deleter.
158 * @param __a An allocator.
159 * @post use_count() == 1 && get() == __p
160 * @throw std::bad_alloc, in which case @a __d(__p) is called.
162 * Requirements: _Deleter's copy constructor and destructor must
163 * not throw _Alloc's copy constructor and destructor must not
166 * __shared_ptr will release __p by calling __d(__p)
168 template<typename _Tp1
, typename _Deleter
, typename _Alloc
>
169 _GLIBCXX_ABI_TAG_EMPTY
170 shared_ptr(_Tp1
* __p
, _Deleter __d
, _Alloc __a
)
171 : __shared_ptr
<_Tp
>(__p
, __d
, std::move(__a
)) { }
174 * @brief Construct a %shared_ptr that owns a null pointer
175 * and the deleter @a __d.
176 * @param __p A null pointer constant.
177 * @param __d A deleter.
178 * @param __a An allocator.
179 * @post use_count() == 1 && get() == __p
180 * @throw std::bad_alloc, in which case @a __d(__p) is called.
182 * Requirements: _Deleter's copy constructor and destructor must
183 * not throw _Alloc's copy constructor and destructor must not
186 * The last owner will call __d(__p)
188 template<typename _Deleter
, typename _Alloc
>
189 _GLIBCXX_ABI_TAG_EMPTY
190 shared_ptr(nullptr_t __p
, _Deleter __d
, _Alloc __a
)
191 : __shared_ptr
<_Tp
>(__p
, __d
, std::move(__a
)) { }
193 // Aliasing constructor
196 * @brief Constructs a %shared_ptr instance that stores @a __p
197 * and shares ownership with @a __r.
198 * @param __r A %shared_ptr.
199 * @param __p A pointer that will remain valid while @a *__r is valid.
200 * @post get() == __p && use_count() == __r.use_count()
202 * This can be used to construct a @c shared_ptr to a sub-object
203 * of an object managed by an existing @c shared_ptr.
206 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
207 * shared_ptr<int> pi(pii, &pii->first);
208 * assert(pii.use_count() == 2);
211 template<typename _Tp1
>
212 shared_ptr(const shared_ptr
<_Tp1
>& __r
, _Tp
* __p
) noexcept
213 : __shared_ptr
<_Tp
>(__r
, __p
) { }
216 * @brief If @a __r is empty, constructs an empty %shared_ptr;
217 * otherwise construct a %shared_ptr that shares ownership
219 * @param __r A %shared_ptr.
220 * @post get() == __r.get() && use_count() == __r.use_count()
222 template<typename _Tp1
, typename
= _Convertible
<_Tp1
*>>
223 shared_ptr(const shared_ptr
<_Tp1
>& __r
) noexcept
224 : __shared_ptr
<_Tp
>(__r
) { }
227 * @brief Move-constructs a %shared_ptr instance from @a __r.
228 * @param __r A %shared_ptr rvalue.
229 * @post *this contains the old value of @a __r, @a __r is empty.
231 shared_ptr(shared_ptr
&& __r
) noexcept
232 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
235 * @brief Move-constructs a %shared_ptr instance from @a __r.
236 * @param __r A %shared_ptr rvalue.
237 * @post *this contains the old value of @a __r, @a __r is empty.
239 template<typename _Tp1
, typename
= _Convertible
<_Tp1
*>>
240 shared_ptr(shared_ptr
<_Tp1
>&& __r
) noexcept
241 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
244 * @brief Constructs a %shared_ptr that shares ownership with @a __r
245 * and stores a copy of the pointer stored in @a __r.
246 * @param __r A weak_ptr.
247 * @post use_count() == __r.use_count()
248 * @throw bad_weak_ptr when __r.expired(),
249 * in which case the constructor has no effect.
251 template<typename _Tp1
>
252 explicit shared_ptr(const weak_ptr
<_Tp1
>& __r
)
253 : __shared_ptr
<_Tp
>(__r
) { }
255 #if _GLIBCXX_USE_DEPRECATED
256 template<typename _Tp1
>
257 shared_ptr(std::auto_ptr
<_Tp1
>&& __r
);
260 // _GLIBCXX_RESOLVE_LIB_DEFECTS
261 // 2399. shared_ptr's constructor from unique_ptr should be constrained
262 template<typename _Tp1
, typename _Del
, typename
263 = _Convertible
<typename unique_ptr
<_Tp1
, _Del
>::pointer
>>
264 shared_ptr(std::unique_ptr
<_Tp1
, _Del
>&& __r
)
265 : __shared_ptr
<_Tp
>(std::move(__r
)) { }
268 * @brief Construct an empty %shared_ptr.
269 * @post use_count() == 0 && get() == nullptr
271 constexpr shared_ptr(nullptr_t
) noexcept
: shared_ptr() { }
273 shared_ptr
& operator=(const shared_ptr
&) noexcept
= default;
275 template<typename _Tp1
>
277 operator=(const shared_ptr
<_Tp1
>& __r
) noexcept
279 this->__shared_ptr
<_Tp
>::operator=(__r
);
283 #if _GLIBCXX_USE_DEPRECATED
284 template<typename _Tp1
>
286 operator=(std::auto_ptr
<_Tp1
>&& __r
)
288 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
294 operator=(shared_ptr
&& __r
) noexcept
296 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
302 operator=(shared_ptr
<_Tp1
>&& __r
) noexcept
304 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
308 template<typename _Tp1
, typename _Del
>
310 operator=(std::unique_ptr
<_Tp1
, _Del
>&& __r
)
312 this->__shared_ptr
<_Tp
>::operator=(std::move(__r
));
317 // This constructor is non-standard, it is used by allocate_shared.
318 template<typename _Alloc
, typename
... _Args
>
319 shared_ptr(_Sp_make_shared_tag __tag
, const _Alloc
& __a
,
321 : __shared_ptr
<_Tp
>(__tag
, __a
, std::forward
<_Args
>(__args
)...)
324 template<typename _Tp1
, typename _Alloc
, typename
... _Args
>
325 friend shared_ptr
<_Tp1
>
326 allocate_shared(const _Alloc
& __a
, _Args
&&... __args
);
328 // This constructor is non-standard, it is used by weak_ptr::lock().
329 shared_ptr(const weak_ptr
<_Tp
>& __r
, std::nothrow_t
)
330 : __shared_ptr
<_Tp
>(__r
, std::nothrow
) { }
332 friend class weak_ptr
<_Tp
>;
335 // 20.7.2.2.7 shared_ptr comparisons
336 template<typename _Tp1
, typename _Tp2
>
338 operator==(const shared_ptr
<_Tp1
>& __a
,
339 const shared_ptr
<_Tp2
>& __b
) noexcept
340 { return __a
.get() == __b
.get(); }
342 template<typename _Tp
>
344 operator==(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
347 template<typename _Tp
>
349 operator==(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
352 template<typename _Tp1
, typename _Tp2
>
354 operator!=(const shared_ptr
<_Tp1
>& __a
,
355 const shared_ptr
<_Tp2
>& __b
) noexcept
356 { return __a
.get() != __b
.get(); }
358 template<typename _Tp
>
360 operator!=(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
361 { return (bool)__a
; }
363 template<typename _Tp
>
365 operator!=(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
366 { return (bool)__a
; }
368 template<typename _Tp1
, typename _Tp2
>
370 operator<(const shared_ptr
<_Tp1
>& __a
,
371 const shared_ptr
<_Tp2
>& __b
) noexcept
373 typedef typename
std::common_type
<_Tp1
*, _Tp2
*>::type _CT
;
374 return std::less
<_CT
>()(__a
.get(), __b
.get());
377 template<typename _Tp
>
379 operator<(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
380 { return std::less
<_Tp
*>()(__a
.get(), nullptr); }
382 template<typename _Tp
>
384 operator<(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
385 { return std::less
<_Tp
*>()(nullptr, __a
.get()); }
387 template<typename _Tp1
, typename _Tp2
>
389 operator<=(const shared_ptr
<_Tp1
>& __a
,
390 const shared_ptr
<_Tp2
>& __b
) noexcept
391 { return !(__b
< __a
); }
393 template<typename _Tp
>
395 operator<=(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
396 { return !(nullptr < __a
); }
398 template<typename _Tp
>
400 operator<=(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
401 { return !(__a
< nullptr); }
403 template<typename _Tp1
, typename _Tp2
>
405 operator>(const shared_ptr
<_Tp1
>& __a
,
406 const shared_ptr
<_Tp2
>& __b
) noexcept
407 { return (__b
< __a
); }
409 template<typename _Tp
>
411 operator>(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
412 { return std::less
<_Tp
*>()(nullptr, __a
.get()); }
414 template<typename _Tp
>
416 operator>(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
417 { return std::less
<_Tp
*>()(__a
.get(), nullptr); }
419 template<typename _Tp1
, typename _Tp2
>
421 operator>=(const shared_ptr
<_Tp1
>& __a
,
422 const shared_ptr
<_Tp2
>& __b
) noexcept
423 { return !(__a
< __b
); }
425 template<typename _Tp
>
427 operator>=(const shared_ptr
<_Tp
>& __a
, nullptr_t
) noexcept
428 { return !(__a
< nullptr); }
430 template<typename _Tp
>
432 operator>=(nullptr_t
, const shared_ptr
<_Tp
>& __a
) noexcept
433 { return !(nullptr < __a
); }
435 template<typename _Tp
>
436 struct less
<shared_ptr
<_Tp
>> : public _Sp_less
<shared_ptr
<_Tp
>>
439 // 20.7.2.2.8 shared_ptr specialized algorithms.
440 template<typename _Tp
>
442 swap(shared_ptr
<_Tp
>& __a
, shared_ptr
<_Tp
>& __b
) noexcept
445 // 20.7.2.2.9 shared_ptr casts.
446 template<typename _Tp
, typename _Tp1
>
447 inline shared_ptr
<_Tp
>
448 static_pointer_cast(const shared_ptr
<_Tp1
>& __r
) noexcept
449 { return shared_ptr
<_Tp
>(__r
, static_cast<_Tp
*>(__r
.get())); }
451 template<typename _Tp
, typename _Tp1
>
452 inline shared_ptr
<_Tp
>
453 const_pointer_cast(const shared_ptr
<_Tp1
>& __r
) noexcept
454 { return shared_ptr
<_Tp
>(__r
, const_cast<_Tp
*>(__r
.get())); }
456 template<typename _Tp
, typename _Tp1
>
457 inline shared_ptr
<_Tp
>
458 dynamic_pointer_cast(const shared_ptr
<_Tp1
>& __r
) noexcept
460 if (_Tp
* __p
= dynamic_cast<_Tp
*>(__r
.get()))
461 return shared_ptr
<_Tp
>(__r
, __p
);
462 return shared_ptr
<_Tp
>();
467 * @brief A smart pointer with weak semantics.
469 * With forwarding constructors and assignment operators.
471 template<typename _Tp
>
472 class weak_ptr
: public __weak_ptr
<_Tp
>
474 template<typename _Ptr
>
476 = typename enable_if
<is_convertible
<_Ptr
, _Tp
*>::value
>::type
;
479 constexpr weak_ptr() noexcept
= default;
481 template<typename _Tp1
, typename
= _Convertible
<_Tp1
*>>
482 weak_ptr(const shared_ptr
<_Tp1
>& __r
) noexcept
483 : __weak_ptr
<_Tp
>(__r
) { }
485 weak_ptr(const weak_ptr
&) noexcept
= default;
487 template<typename _Tp1
, typename
= _Convertible
<_Tp1
*>>
488 weak_ptr(const weak_ptr
<_Tp1
>& __r
) noexcept
489 : __weak_ptr
<_Tp
>(__r
) { }
491 weak_ptr(weak_ptr
&&) noexcept
= default;
493 template<typename _Tp1
, typename
= _Convertible
<_Tp1
*>>
494 weak_ptr(weak_ptr
<_Tp1
>&& __r
) noexcept
495 : __weak_ptr
<_Tp
>(std::move(__r
)) { }
498 operator=(const weak_ptr
& __r
) noexcept
= default;
500 template<typename _Tp1
>
502 operator=(const weak_ptr
<_Tp1
>& __r
) noexcept
504 this->__weak_ptr
<_Tp
>::operator=(__r
);
508 template<typename _Tp1
>
510 operator=(const shared_ptr
<_Tp1
>& __r
) noexcept
512 this->__weak_ptr
<_Tp
>::operator=(__r
);
517 operator=(weak_ptr
&& __r
) noexcept
= default;
519 template<typename _Tp1
>
521 operator=(weak_ptr
<_Tp1
>&& __r
) noexcept
523 this->__weak_ptr
<_Tp
>::operator=(std::move(__r
));
528 lock() const noexcept
529 { return shared_ptr
<_Tp
>(*this, std::nothrow
); }
532 // 20.7.2.3.6 weak_ptr specialized algorithms.
533 template<typename _Tp
>
535 swap(weak_ptr
<_Tp
>& __a
, weak_ptr
<_Tp
>& __b
) noexcept
539 /// Primary template owner_less
540 template<typename _Tp
>
543 /// Partial specialization of owner_less for shared_ptr.
544 template<typename _Tp
>
545 struct owner_less
<shared_ptr
<_Tp
>>
546 : public _Sp_owner_less
<shared_ptr
<_Tp
>, weak_ptr
<_Tp
>>
549 /// Partial specialization of owner_less for weak_ptr.
550 template<typename _Tp
>
551 struct owner_less
<weak_ptr
<_Tp
>>
552 : public _Sp_owner_less
<weak_ptr
<_Tp
>, shared_ptr
<_Tp
>>
556 * @brief Base class allowing use of member function shared_from_this.
558 template<typename _Tp
>
559 class enable_shared_from_this
562 constexpr enable_shared_from_this() noexcept
{ }
564 enable_shared_from_this(const enable_shared_from_this
&) noexcept
{ }
566 enable_shared_from_this
&
567 operator=(const enable_shared_from_this
&) noexcept
570 ~enable_shared_from_this() { }
575 { return shared_ptr
<_Tp
>(this->_M_weak_this
); }
577 shared_ptr
<const _Tp
>
578 shared_from_this() const
579 { return shared_ptr
<const _Tp
>(this->_M_weak_this
); }
582 template<typename _Tp1
>
584 _M_weak_assign(_Tp1
* __p
, const __shared_count
<>& __n
) const noexcept
585 { _M_weak_this
._M_assign(__p
, __n
); }
587 template<typename _Tp1
, typename _Tp2
>
589 __enable_shared_from_this_helper(const __shared_count
<>&,
590 const enable_shared_from_this
<_Tp1
>*,
591 const _Tp2
*) noexcept
;
593 mutable weak_ptr
<_Tp
> _M_weak_this
;
596 template<typename _Tp1
, typename _Tp2
>
598 __enable_shared_from_this_helper(const __shared_count
<>& __pn
,
599 const enable_shared_from_this
<_Tp1
>*
600 __pe
, const _Tp2
* __px
) noexcept
603 __pe
->_M_weak_assign(const_cast<_Tp2
*>(__px
), __pn
);
607 * @brief Create an object that is owned by a shared_ptr.
608 * @param __a An allocator.
609 * @param __args Arguments for the @a _Tp object's constructor.
610 * @return A shared_ptr that owns the newly created object.
611 * @throw An exception thrown from @a _Alloc::allocate or from the
612 * constructor of @a _Tp.
614 * A copy of @a __a will be used to allocate memory for the shared_ptr
615 * and the new object.
617 template<typename _Tp
, typename _Alloc
, typename
... _Args
>
618 inline shared_ptr
<_Tp
>
619 allocate_shared(const _Alloc
& __a
, _Args
&&... __args
)
621 return shared_ptr
<_Tp
>(_Sp_make_shared_tag(), __a
,
622 std::forward
<_Args
>(__args
)...);
626 * @brief Create an object that is owned by a shared_ptr.
627 * @param __args Arguments for the @a _Tp object's constructor.
628 * @return A shared_ptr that owns the newly created object.
629 * @throw std::bad_alloc, or an exception thrown from the
630 * constructor of @a _Tp.
632 template<typename _Tp
, typename
... _Args
>
633 inline shared_ptr
<_Tp
>
634 make_shared(_Args
&&... __args
)
636 typedef typename
std::remove_const
<_Tp
>::type _Tp_nc
;
637 return std::allocate_shared
<_Tp
>(std::allocator
<_Tp_nc
>(),
638 std::forward
<_Args
>(__args
)...);
641 /// std::hash specialization for shared_ptr.
642 template<typename _Tp
>
643 struct hash
<shared_ptr
<_Tp
>>
644 : public __hash_base
<size_t, shared_ptr
<_Tp
>>
647 operator()(const shared_ptr
<_Tp
>& __s
) const noexcept
648 { return std::hash
<_Tp
*>()(__s
.get()); }
651 // @} group pointer_abstractions
653 _GLIBCXX_END_NAMESPACE_VERSION
656 #endif // _SHARED_PTR_H