1 // shared_ptr and weak_ptr implementation -*- C++ -*-
3 // Copyright (C) 2007, 2008, 2009 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/>.
26 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
29 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
30 // Copyright (C) 2001, 2002, 2003 Peter Dimov
33 // Copyright (C) 2001, 2002, 2003 Peter Dimov
35 // enable_shared_from_this.hpp
36 // Copyright (C) 2002 Peter Dimov
38 // Distributed under the Boost Software License, Version 1.0. (See
39 // accompanying file LICENSE_1_0.txt or copy at
40 // http://www.boost.org/LICENSE_1_0.txt)
42 // GCC Note: based on version 1.32.0 of the Boost library.
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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
53 # include <c++0x_warning.h>
56 #if defined(_GLIBCXX_INCLUDE_AS_TR1)
57 # error C++0x header cannot be included from TR1 header
60 _GLIBCXX_BEGIN_NAMESPACE(std)
63 * @addtogroup pointer_abstractions
67 // counted ptr with no deleter or allocator support
68 template<typename _Ptr, _Lock_policy _Lp>
70 : public _Sp_counted_base<_Lp>
73 _Sp_counted_ptr(_Ptr __p)
77 _M_dispose() // nothrow
81 _M_destroy() // nothrow
85 _M_get_deleter(const std::type_info& __ti)
88 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
89 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
92 _Ptr _M_ptr; // copy constructor must not throw
95 // support for custom deleter and/or allocator
96 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
97 class _Sp_counted_deleter
98 : public _Sp_counted_ptr<_Ptr, _Lp>
100 typedef typename _Alloc::template
101 rebind<_Sp_counted_deleter>::other _My_alloc_type;
103 // Helper class that stores the Deleter and also acts as an allocator.
104 // Used to dispose of the owned pointer and the internal refcount
105 // Requires that copies of _Alloc can free each other's memory.
107 : public _My_alloc_type // copy constructor must not throw
109 _Deleter _M_del; // copy constructor must not throw
110 _My_Deleter(_Deleter __d, const _Alloc& __a)
111 : _My_alloc_type(__a), _M_del(__d) { }
115 typedef _Sp_counted_ptr<_Ptr, _Lp> _Base_type;
120 * @pre __d(__p) must not throw.
122 _Sp_counted_deleter(_Ptr __p, _Deleter __d)
123 : _Base_type(__p), _M_del(__d, _Alloc()) { }
127 * @pre __d(__p) must not throw.
129 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a)
130 : _Base_type(__p), _M_del(__d, __a) { }
133 _M_dispose() // nothrow
134 { _M_del._M_del(_Base_type::_M_ptr); }
137 _M_destroy() // nothrow
139 _My_alloc_type __a(_M_del);
140 this->~_Sp_counted_deleter();
141 __a.deallocate(this, 1);
145 _M_get_deleter(const std::type_info& __ti)
146 { return __ti == typeid(_Deleter) ? &_M_del._M_del : 0; }
149 _My_Deleter _M_del; // copy constructor must not throw
152 // helpers for make_shared / allocate_shared
154 template<typename _Tp>
155 struct _Sp_destroy_inplace
157 void operator()(_Tp* __p) const { if (__p) __p->~_Tp(); }
160 struct _Sp_make_shared_tag { };
162 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
163 class _Sp_counted_ptr_inplace
164 : public _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp>
166 typedef _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp>
170 _Sp_counted_ptr_inplace(_Alloc __a)
171 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a)
174 void* __p = &_M_storage;
175 ::new (__p) _Tp(); // might throw
176 _Base_type::_Base_type::_M_ptr = static_cast<_Tp*>(__p);
179 template<typename... _Args>
180 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
181 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a)
184 void* __p = &_M_storage;
185 ::new (__p) _Tp(std::forward<_Args>(__args)...); // might throw
186 _Base_type::_Base_type::_M_ptr = static_cast<_Tp*>(__p);
189 // override because the allocator needs to know the dynamic type
191 _M_destroy() // nothrow
193 typedef typename _Alloc::template
194 rebind<_Sp_counted_ptr_inplace>::other _My_alloc_type;
195 _My_alloc_type __a(_Base_type::_M_del);
196 this->~_Sp_counted_ptr_inplace();
197 __a.deallocate(this, 1);
200 // sneaky trick so __shared_ptr can get the managed pointer
202 _M_get_deleter(const std::type_info& __ti)
204 return __ti == typeid(_Sp_make_shared_tag)
205 ? static_cast<void*>(&_M_storage)
206 : _Base_type::_M_get_deleter(__ti);
210 typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type
214 template<_Lock_policy _Lp = __default_lock_policy>
217 template<_Lock_policy _Lp = __default_lock_policy>
222 : _M_pi(0) // nothrow
225 template<typename _Ptr>
226 __shared_count(_Ptr __p) : _M_pi(0)
230 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
235 __throw_exception_again;
239 template<typename _Ptr, typename _Deleter>
240 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0)
242 // allocator's value_type doesn't matter, will rebind it anyway
243 typedef std::allocator<int> _Alloc;
244 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
245 typedef std::allocator<_Sp_cd_type> _Alloc2;
249 _M_pi = __a2.allocate(1);
250 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d);
254 __d(__p); // Call _Deleter on __p.
256 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1);
257 __throw_exception_again;
261 template<typename _Ptr, typename _Deleter, typename _Alloc>
262 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
264 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
265 typedef typename _Alloc::template rebind<_Sp_cd_type>::other _Alloc2;
269 _M_pi = __a2.allocate(1);
270 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d, __a);
274 __d(__p); // Call _Deleter on __p.
276 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1);
277 __throw_exception_again;
281 template<typename _Tp, typename _Alloc, typename... _Args>
282 __shared_count(_Sp_make_shared_tag, _Tp*, _Alloc __a, _Args&&... __args)
285 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
286 typedef typename _Alloc::template rebind<_Sp_cp_type>::other _Alloc2;
290 _M_pi = __a2.allocate(1);
291 ::new(static_cast<void*>(_M_pi)) _Sp_cp_type(__a,
292 std::forward<_Args>(__args)...);
297 __a2.deallocate(static_cast<_Sp_cp_type*>(_M_pi), 1);
298 __throw_exception_again;
302 #if _GLIBCXX_DEPRECATED
303 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
304 template<typename _Tp>
306 __shared_count(std::auto_ptr<_Tp>&& __r)
307 : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get()))
311 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
312 template<typename _Tp, typename _Del>
314 __shared_count(std::unique_ptr<_Tp, _Del>&& __r)
315 : _M_pi(_S_create_from_up(std::move(__r)))
318 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
320 __shared_count(const __weak_count<_Lp>& __r);
322 ~__shared_count() // nothrow
328 __shared_count(const __shared_count& __r)
329 : _M_pi(__r._M_pi) // nothrow
332 _M_pi->_M_add_ref_copy();
336 operator=(const __shared_count& __r) // nothrow
338 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
342 __tmp->_M_add_ref_copy();
351 _M_swap(__shared_count& __r) // nothrow
353 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
359 _M_get_use_count() const // nothrow
360 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
363 _M_unique() const // nothrow
364 { return this->_M_get_use_count() == 1; }
367 _M_get_deleter(const std::type_info& __ti) const
368 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; }
371 _M_less(const __shared_count& __rhs) const
372 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
375 _M_less(const __weak_count<_Lp>& __rhs) const
376 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
378 // friend function injected into enclosing namespace and found by ADL
380 operator==(const __shared_count& __a, const __shared_count& __b)
381 { return __a._M_pi == __b._M_pi; }
384 friend class __weak_count<_Lp>;
386 template<typename _Tp, typename _Del>
387 static _Sp_counted_base<_Lp>*
388 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
389 typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0)
391 return new _Sp_counted_deleter<_Tp*, _Del, std::allocator<_Tp>,
392 _Lp>(__r.get(), __r.get_deleter());
395 template<typename _Tp, typename _Del>
396 static _Sp_counted_base<_Lp>*
397 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
398 typename std::enable_if<std::is_reference<_Del>::value>::type* = 0)
400 typedef typename std::remove_reference<_Del>::type _Del1;
401 typedef std::reference_wrapper<_Del1> _Del2;
402 return new _Sp_counted_deleter<_Tp*, _Del2, std::allocator<_Tp>,
403 _Lp>(__r.get(), std::ref(__r.get_deleter()));
406 _Sp_counted_base<_Lp>* _M_pi;
410 template<_Lock_policy _Lp>
415 : _M_pi(0) // nothrow
418 __weak_count(const __shared_count<_Lp>& __r)
419 : _M_pi(__r._M_pi) // nothrow
422 _M_pi->_M_weak_add_ref();
425 __weak_count(const __weak_count<_Lp>& __r)
426 : _M_pi(__r._M_pi) // nothrow
429 _M_pi->_M_weak_add_ref();
432 ~__weak_count() // nothrow
435 _M_pi->_M_weak_release();
439 operator=(const __shared_count<_Lp>& __r) // nothrow
441 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
443 __tmp->_M_weak_add_ref();
445 _M_pi->_M_weak_release();
451 operator=(const __weak_count<_Lp>& __r) // nothrow
453 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
455 __tmp->_M_weak_add_ref();
457 _M_pi->_M_weak_release();
463 _M_swap(__weak_count<_Lp>& __r) // nothrow
465 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
471 _M_get_use_count() const // nothrow
472 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
475 _M_less(const __weak_count& __rhs) const
476 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
479 _M_less(const __shared_count<_Lp>& __rhs) const
480 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
482 // friend function injected into enclosing namespace and found by ADL
484 operator==(const __weak_count& __a, const __weak_count& __b)
485 { return __a._M_pi == __b._M_pi; }
488 friend class __shared_count<_Lp>;
490 _Sp_counted_base<_Lp>* _M_pi;
493 // now that __weak_count is defined we can define this constructor:
494 template<_Lock_policy _Lp>
496 __shared_count<_Lp>::
497 __shared_count(const __weak_count<_Lp>& __r)
501 _M_pi->_M_add_ref_lock();
503 __throw_bad_weak_ptr();
506 // Forward declarations.
507 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
510 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
513 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
514 class __enable_shared_from_this;
516 template<typename _Tp>
519 template<typename _Tp>
522 template<typename _Tp>
523 class enable_shared_from_this;
525 // Support for enable_shared_from_this.
527 // Friend of __enable_shared_from_this.
528 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2>
530 __enable_shared_from_this_helper(const __shared_count<_Lp>&,
531 const __enable_shared_from_this<_Tp1,
534 // Friend of enable_shared_from_this.
535 template<typename _Tp1, typename _Tp2>
537 __enable_shared_from_this_helper(const __shared_count<>&,
538 const enable_shared_from_this<_Tp1>*,
541 template<_Lock_policy _Lp>
543 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...)
547 template<typename _Tp, _Lock_policy _Lp>
551 typedef _Tp element_type;
553 /** @brief Construct an empty %__shared_ptr.
554 * @post use_count()==0 && get()==0
557 : _M_ptr(0), _M_refcount() // never throws
560 /** @brief Construct a %__shared_ptr that owns the pointer @a __p.
561 * @param __p A pointer that is convertible to element_type*.
562 * @post use_count() == 1 && get() == __p
563 * @throw std::bad_alloc, in which case @c delete @a __p is called.
565 template<typename _Tp1>
567 __shared_ptr(_Tp1* __p)
568 : _M_ptr(__p), _M_refcount(__p)
570 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
571 // __glibcxx_function_requires(_CompleteConcept<_Tp1*>)
572 __enable_shared_from_this_helper(_M_refcount, __p, __p);
576 // Requirements: _Deleter's copy constructor and destructor must
579 // __shared_ptr will release __p by calling __d(__p)
581 /** @brief Construct a %__shared_ptr that owns the pointer @a __p
582 * and the deleter @a __d.
583 * @param __p A pointer.
584 * @param __d A deleter.
585 * @post use_count() == 1 && get() == __p
586 * @throw std::bad_alloc, in which case @a __d(__p) is called.
588 template<typename _Tp1, typename _Deleter>
589 __shared_ptr(_Tp1* __p, _Deleter __d)
590 : _M_ptr(__p), _M_refcount(__p, __d)
592 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
593 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
594 __enable_shared_from_this_helper(_M_refcount, __p, __p);
598 // Requirements: _Deleter's copy constructor and destructor must
599 // not throw _Alloc's copy constructor and destructor must not
602 // __shared_ptr will release __p by calling __d(__p)
604 /** @brief Construct a %__shared_ptr that owns the pointer @a __p
605 * and the deleter @a __d.
606 * @param __p A pointer.
607 * @param __d A deleter.
608 * @param __a An allocator.
609 * @post use_count() == 1 && get() == __p
610 * @throw std::bad_alloc, in which case @a __d(__p) is called.
612 template<typename _Tp1, typename _Deleter, typename _Alloc>
613 __shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
614 : _M_ptr(__p), _M_refcount(__p, __d, __a)
616 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
617 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
618 __enable_shared_from_this_helper(_M_refcount, __p, __p);
621 /** @brief Constructs a %__shared_ptr instance that stores @a __p
622 * and shares ownership with @a __r.
623 * @param __r A %__shared_ptr.
624 * @param __p A pointer that will remain valid while @a *__r is valid.
625 * @post get() == __p && use_count() == __r.use_count()
627 * This can be used to construct a @c shared_ptr to a sub-object
628 * of an object managed by an existing @c shared_ptr.
631 * shared_ptr< pair<int,int> > pii(new pair<int,int>());
632 * shared_ptr<int> pi(pii, &pii->first);
633 * assert(pii.use_count() == 2);
636 template<typename _Tp1>
637 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p)
638 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
641 // generated copy constructor, assignment, destructor are fine.
643 /** @brief If @a __r is empty, constructs an empty %__shared_ptr;
644 * otherwise construct a %__shared_ptr that shares ownership
646 * @param __r A %__shared_ptr.
647 * @post get() == __r.get() && use_count() == __r.use_count()
649 template<typename _Tp1>
650 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
651 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
652 { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) }
654 /** @brief Move-constructs a %__shared_ptr instance from @a __r.
655 * @param __r A %__shared_ptr rvalue.
656 * @post *this contains the old value of @a __r, @a __r is empty.
658 __shared_ptr(__shared_ptr&& __r)
659 : _M_ptr(__r._M_ptr), _M_refcount() // never throws
661 _M_refcount._M_swap(__r._M_refcount);
665 /** @brief Move-constructs a %__shared_ptr instance from @a __r.
666 * @param __r A %__shared_ptr rvalue.
667 * @post *this contains the old value of @a __r, @a __r is empty.
669 template<typename _Tp1>
670 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r)
671 : _M_ptr(__r._M_ptr), _M_refcount() // never throws
673 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
674 _M_refcount._M_swap(__r._M_refcount);
678 /** @brief Constructs a %__shared_ptr that shares ownership with @a __r
679 * and stores a copy of the pointer stored in @a __r.
680 * @param __r A weak_ptr.
681 * @post use_count() == __r.use_count()
682 * @throw bad_weak_ptr when __r.expired(),
683 * in which case the constructor has no effect.
685 template<typename _Tp1>
687 __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
688 : _M_refcount(__r._M_refcount) // may throw
690 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
691 // It is now safe to copy __r._M_ptr, as _M_refcount(__r._M_refcount)
696 template<typename _Tp1, typename _Del>
698 __shared_ptr(const std::unique_ptr<_Tp1, _Del>&) = delete;
701 * If an exception is thrown this constructor has no effect.
703 template<typename _Tp1, typename _Del>
705 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
706 : _M_ptr(__r.get()), _M_refcount()
708 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
709 _Tp1* __tmp = __r.get();
710 _M_refcount = __shared_count<_Lp>(std::move(__r));
711 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
714 #if _GLIBCXX_DEPRECATED
716 * @post use_count() == 1 and __r.get() == 0
718 template<typename _Tp1>
720 __shared_ptr(std::auto_ptr<_Tp1>&& __r)
721 : _M_ptr(__r.get()), _M_refcount()
723 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
724 // TODO requires _Tp1 is complete, delete __r.release() well-formed
725 _Tp1* __tmp = __r.get();
726 _M_refcount = __shared_count<_Lp>(std::move(__r));
727 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
731 template<typename _Tp1>
733 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
736 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
740 #if _GLIBCXX_DEPRECATED
741 template<typename _Tp1>
743 operator=(std::auto_ptr<_Tp1>&& __r)
745 __shared_ptr(std::move(__r)).swap(*this);
751 operator=(__shared_ptr&& __r)
753 __shared_ptr(std::move(__r)).swap(*this);
759 operator=(__shared_ptr<_Tp1, _Lp>&& __r)
761 __shared_ptr(std::move(__r)).swap(*this);
765 template<typename _Tp1, typename _Del>
767 operator=(const std::unique_ptr<_Tp1, _Del>& __r) = delete;
769 template<typename _Tp1, typename _Del>
771 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
773 __shared_ptr(std::move(__r)).swap(*this);
778 reset() // never throws
779 { __shared_ptr().swap(*this); }
781 template<typename _Tp1>
783 reset(_Tp1* __p) // _Tp1 must be complete.
785 // Catch self-reset errors.
786 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr);
787 __shared_ptr(__p).swap(*this);
790 template<typename _Tp1, typename _Deleter>
792 reset(_Tp1* __p, _Deleter __d)
793 { __shared_ptr(__p, __d).swap(*this); }
795 template<typename _Tp1, typename _Deleter, typename _Alloc>
797 reset(_Tp1* __p, _Deleter __d, const _Alloc& __a)
798 { __shared_ptr(__p, __d, __a).swap(*this); }
800 // Allow class instantiation when _Tp is [cv-qual] void.
801 typename std::add_lvalue_reference<_Tp>::type
802 operator*() const // never throws
804 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
809 operator->() const // never throws
811 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
816 get() const // never throws
819 explicit operator bool() const // never throws
820 { return _M_ptr == 0 ? false : true; }
823 unique() const // never throws
824 { return _M_refcount._M_unique(); }
827 use_count() const // never throws
828 { return _M_refcount._M_get_use_count(); }
831 swap(__shared_ptr<_Tp, _Lp>& __other) // never throws
833 std::swap(_M_ptr, __other._M_ptr);
834 _M_refcount._M_swap(__other._M_refcount);
837 template<typename _Tp1>
839 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const
840 { return _M_refcount._M_less(__rhs._M_refcount); }
842 template<typename _Tp1>
844 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const
845 { return _M_refcount._M_less(__rhs._M_refcount); }
848 // This constructor is non-standard, it is used by allocate_shared.
849 template<typename _Alloc, typename... _Args>
850 __shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
851 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
852 std::forward<_Args>(__args)...)
854 // _M_ptr needs to point to the newly constructed object.
855 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
856 void* __p = _M_refcount._M_get_deleter(typeid(__tag));
857 _M_ptr = static_cast<_Tp*>(__p);
858 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
861 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
863 friend __shared_ptr<_Tp1, _Lp1>
864 __allocate_shared(_Alloc __a, _Args&&... __args);
868 _M_get_deleter(const std::type_info& __ti) const
869 { return _M_refcount._M_get_deleter(__ti); }
871 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
872 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
874 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
875 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&);
877 _Tp* _M_ptr; // Contained pointer.
878 __shared_count<_Lp> _M_refcount; // Reference counter.
881 // 20.8.13.2.7 shared_ptr comparisons
882 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
884 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
885 const __shared_ptr<_Tp2, _Lp>& __b)
886 { return __a.get() == __b.get(); }
888 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
890 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
891 const __shared_ptr<_Tp2, _Lp>& __b)
892 { return __a.get() != __b.get(); }
894 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
896 operator<(const __shared_ptr<_Tp1, _Lp>& __a,
897 const __shared_ptr<_Tp2, _Lp>& __b)
898 { return __a.get() < __b.get(); }
900 template<typename _Sp>
901 struct _Sp_less : public binary_function<_Sp, _Sp, bool>
904 operator()(const _Sp& __lhs, const _Sp& __rhs) const
906 return std::less<typename _Sp::element_type*>()(__lhs.get(),
911 template<typename _Tp, _Lock_policy _Lp>
912 struct less<__shared_ptr<_Tp, _Lp>>
913 : public _Sp_less<__shared_ptr<_Tp, _Lp>>
916 // XXX LessThanComparable<_Tp> concept should provide >, >= and <=
917 template<typename _Tp, _Lock_policy _Lp>
919 operator>(const __shared_ptr<_Tp, _Lp>& __a,
920 const __shared_ptr<_Tp, _Lp>& __b)
921 { return __a.get() > __b.get(); }
923 template<typename _Tp, _Lock_policy _Lp>
925 operator>=(const __shared_ptr<_Tp, _Lp>& __a,
926 const __shared_ptr<_Tp, _Lp>& __b)
927 { return __a.get() >= __b.get(); }
929 template<typename _Tp, _Lock_policy _Lp>
931 operator<=(const __shared_ptr<_Tp, _Lp>& __a,
932 const __shared_ptr<_Tp, _Lp>& __b)
933 { return __a.get() <= __b.get(); }
935 // 2.2.3.8 shared_ptr specialized algorithms.
936 template<typename _Tp, _Lock_policy _Lp>
938 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b)
941 // 2.2.3.9 shared_ptr casts
942 /** @warning The seemingly equivalent
943 * <code>shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))</code>
944 * will eventually result in undefined behaviour,
945 * attempting to delete the same object twice.
947 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
948 inline __shared_ptr<_Tp, _Lp>
949 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
950 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); }
952 /** @warning The seemingly equivalent
953 * <code>shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))</code>
954 * will eventually result in undefined behaviour,
955 * attempting to delete the same object twice.
957 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
958 inline __shared_ptr<_Tp, _Lp>
959 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
960 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); }
962 /** @warning The seemingly equivalent
963 * <code>shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))</code>
964 * will eventually result in undefined behaviour,
965 * attempting to delete the same object twice.
967 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
968 inline __shared_ptr<_Tp, _Lp>
969 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
971 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
972 return __shared_ptr<_Tp, _Lp>(__r, __p);
973 return __shared_ptr<_Tp, _Lp>();
976 // 2.2.3.7 shared_ptr I/O
977 template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
978 std::basic_ostream<_Ch, _Tr>&
979 operator<<(std::basic_ostream<_Ch, _Tr>& __os,
980 const __shared_ptr<_Tp, _Lp>& __p)
986 // 2.2.3.10 shared_ptr get_deleter (experimental)
987 template<typename _Del, typename _Tp, _Lock_policy _Lp>
989 get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
990 { return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); }
993 template<typename _Tp, _Lock_policy _Lp>
997 typedef _Tp element_type;
1000 : _M_ptr(0), _M_refcount() // never throws
1003 // Generated copy constructor, assignment, destructor are fine.
1005 // The "obvious" converting constructor implementation:
1007 // template<typename _Tp1>
1008 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1009 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1012 // has a serious problem.
1014 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1015 // conversion may require access to *__r._M_ptr (virtual inheritance).
1017 // It is not possible to avoid spurious access violations since
1018 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1019 template<typename _Tp1>
1020 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1021 : _M_refcount(__r._M_refcount) // never throws
1023 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
1024 _M_ptr = __r.lock().get();
1027 template<typename _Tp1>
1028 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
1029 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1030 { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) }
1032 template<typename _Tp1>
1034 operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws
1036 _M_ptr = __r.lock().get();
1037 _M_refcount = __r._M_refcount;
1041 template<typename _Tp1>
1043 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
1045 _M_ptr = __r._M_ptr;
1046 _M_refcount = __r._M_refcount;
1050 __shared_ptr<_Tp, _Lp>
1051 lock() const // never throws
1054 // Optimization: avoid throw overhead.
1056 return __shared_ptr<element_type, _Lp>();
1060 return __shared_ptr<element_type, _Lp>(*this);
1062 __catch(const bad_weak_ptr&)
1064 // Q: How can we get here?
1065 // A: Another thread may have invalidated r after the
1066 // use_count test above.
1067 return __shared_ptr<element_type, _Lp>();
1071 // Optimization: avoid try/catch overhead when single threaded.
1072 return expired() ? __shared_ptr<element_type, _Lp>()
1073 : __shared_ptr<element_type, _Lp>(*this);
1079 use_count() const // never throws
1080 { return _M_refcount._M_get_use_count(); }
1083 expired() const // never throws
1084 { return _M_refcount._M_get_use_count() == 0; }
1086 template<typename _Tp1>
1088 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const
1089 { return _M_refcount._M_less(__rhs._M_refcount); }
1091 template<typename _Tp1>
1093 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const
1094 { return _M_refcount._M_less(__rhs._M_refcount); }
1097 reset() // never throws
1098 { __weak_ptr().swap(*this); }
1101 swap(__weak_ptr& __s) // never throws
1103 std::swap(_M_ptr, __s._M_ptr);
1104 _M_refcount._M_swap(__s._M_refcount);
1108 template<typename _Tp1>
1109 bool operator<(const __weak_ptr<_Tp1, _Lp>&) const = delete;
1110 template<typename _Tp1>
1111 bool operator<=(const __weak_ptr<_Tp1, _Lp>&) const = delete;
1112 template<typename _Tp1>
1113 bool operator>(const __weak_ptr<_Tp1, _Lp>&) const = delete;
1114 template<typename _Tp1>
1115 bool operator>=(const __weak_ptr<_Tp1, _Lp>&) const = delete;
1118 // Used by __enable_shared_from_this.
1120 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount)
1123 _M_refcount = __refcount;
1126 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1127 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1128 friend class __enable_shared_from_this<_Tp, _Lp>;
1129 friend class enable_shared_from_this<_Tp>;
1131 _Tp* _M_ptr; // Contained pointer.
1132 __weak_count<_Lp> _M_refcount; // Reference counter.
1135 // 20.8.13.3.7 weak_ptr specialized algorithms.
1136 template<typename _Tp, _Lock_policy _Lp>
1138 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b)
1142 template<typename _Tp> struct owner_less;
1144 template<typename _Tp, typename _Tp1>
1145 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1148 operator()(const _Tp& __lhs, const _Tp& __rhs) const
1149 { return __lhs.owner_before(__rhs); }
1151 operator()(const _Tp& __lhs, const _Tp1& __rhs) const
1152 { return __lhs.owner_before(__rhs); }
1154 operator()(const _Tp1& __lhs, const _Tp& __rhs) const
1155 { return __lhs.owner_before(__rhs); }
1158 template<typename _Tp, _Lock_policy _Lp>
1159 struct owner_less<__shared_ptr<_Tp, _Lp>>
1160 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1163 template<typename _Tp, _Lock_policy _Lp>
1164 struct owner_less<__weak_ptr<_Tp, _Lp>>
1165 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1170 template<typename _Tp, _Lock_policy _Lp>
1171 class __enable_shared_from_this
1174 __enable_shared_from_this() { }
1176 __enable_shared_from_this(const __enable_shared_from_this&) { }
1178 __enable_shared_from_this&
1179 operator=(const __enable_shared_from_this&)
1182 ~__enable_shared_from_this() { }
1185 __shared_ptr<_Tp, _Lp>
1187 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1189 __shared_ptr<const _Tp, _Lp>
1190 shared_from_this() const
1191 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1194 template<typename _Tp1>
1196 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const
1197 { _M_weak_this._M_assign(__p, __n); }
1199 template<typename _Tp1>
1201 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn,
1202 const __enable_shared_from_this* __pe,
1206 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
1209 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1213 * @brief A smart pointer with reference-counted copy semantics.
1215 * The object pointed to is deleted when the last shared_ptr pointing to
1216 * it is destroyed or reset.
1218 template<typename _Tp>
1220 : public __shared_ptr<_Tp>
1224 : __shared_ptr<_Tp>() { }
1226 template<typename _Tp1>
1228 shared_ptr(_Tp1* __p)
1229 : __shared_ptr<_Tp>(__p) { }
1231 template<typename _Tp1, typename _Deleter>
1232 shared_ptr(_Tp1* __p, _Deleter __d)
1233 : __shared_ptr<_Tp>(__p, __d) { }
1235 template<typename _Tp1, typename _Deleter, typename _Alloc>
1236 shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
1237 : __shared_ptr<_Tp>(__p, __d, __a) { }
1239 // Aliasing constructor
1240 template<typename _Tp1>
1241 shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
1242 : __shared_ptr<_Tp>(__r, __p) { }
1244 template<typename _Tp1>
1245 shared_ptr(const shared_ptr<_Tp1>& __r)
1246 : __shared_ptr<_Tp>(__r) { }
1248 shared_ptr(shared_ptr&& __r)
1249 : __shared_ptr<_Tp>(std::move(__r)) { }
1251 template<typename _Tp1>
1252 shared_ptr(shared_ptr<_Tp1>&& __r)
1253 : __shared_ptr<_Tp>(std::move(__r)) { }
1255 template<typename _Tp1>
1257 shared_ptr(const weak_ptr<_Tp1>& __r)
1258 : __shared_ptr<_Tp>(__r) { }
1260 #if _GLIBCXX_DEPRECATED
1261 template<typename _Tp1>
1263 shared_ptr(std::auto_ptr<_Tp1>&& __r)
1264 : __shared_ptr<_Tp>(std::move(__r)) { }
1267 template<typename _Tp1, typename _Del>
1269 shared_ptr(const std::unique_ptr<_Tp1, _Del>&) = delete;
1271 template<typename _Tp1, typename _Del>
1273 shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
1274 : __shared_ptr<_Tp>(std::move(__r)) { }
1276 template<typename _Tp1>
1278 operator=(const shared_ptr<_Tp1>& __r) // never throws
1280 this->__shared_ptr<_Tp>::operator=(__r);
1284 #if _GLIBCXX_DEPRECATED
1285 template<typename _Tp1>
1287 operator=(std::auto_ptr<_Tp1>&& __r)
1289 this->__shared_ptr<_Tp>::operator=(std::move(__r));
1295 operator=(shared_ptr&& __r)
1297 this->__shared_ptr<_Tp>::operator=(std::move(__r));
1301 template<class _Tp1>
1303 operator=(shared_ptr<_Tp1>&& __r)
1305 this->__shared_ptr<_Tp>::operator=(std::move(__r));
1309 template<typename _Tp1, typename _Del>
1311 operator=(const std::unique_ptr<_Tp1, _Del>& __r) = delete;
1313 template<typename _Tp1, typename _Del>
1315 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
1317 this->__shared_ptr<_Tp>::operator=(std::move(__r));
1322 // This constructor is non-standard, it is used by allocate_shared.
1323 template<typename _Alloc, typename... _Args>
1324 shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
1325 : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
1328 template<typename _Tp1, typename _Alloc, typename... _Args>
1329 friend shared_ptr<_Tp1>
1330 allocate_shared(_Alloc __a, _Args&&... __args);
1333 // 20.8.13.2.7 shared_ptr comparisons
1334 template<typename _Tp1, typename _Tp2>
1336 operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
1337 { return __a.get() == __b.get(); }
1339 template<typename _Tp1, typename _Tp2>
1341 operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
1342 { return __a.get() != __b.get(); }
1344 template<typename _Tp1, typename _Tp2>
1346 operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
1347 { return __a.get() < __b.get(); }
1349 template<typename _Tp>
1350 struct less<shared_ptr<_Tp>>
1351 : public _Sp_less<shared_ptr<_Tp>>
1354 // 20.8.13.2.9 shared_ptr specialized algorithms.
1355 template<typename _Tp>
1357 swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
1360 // 20.8.13.2.10 shared_ptr casts.
1361 template<typename _Tp, typename _Tp1>
1362 inline shared_ptr<_Tp>
1363 static_pointer_cast(const shared_ptr<_Tp1>& __r)
1364 { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
1366 template<typename _Tp, typename _Tp1>
1367 inline shared_ptr<_Tp>
1368 const_pointer_cast(const shared_ptr<_Tp1>& __r)
1369 { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
1371 template<typename _Tp, typename _Tp1>
1372 inline shared_ptr<_Tp>
1373 dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
1375 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
1376 return shared_ptr<_Tp>(__r, __p);
1377 return shared_ptr<_Tp>();
1382 * @brief A smart pointer with weak semantics.
1384 * With forwarding constructors and assignment operators.
1386 template<typename _Tp>
1388 : public __weak_ptr<_Tp>
1392 : __weak_ptr<_Tp>() { }
1394 template<typename _Tp1>
1395 weak_ptr(const weak_ptr<_Tp1>& __r)
1396 : __weak_ptr<_Tp>(__r) { }
1398 template<typename _Tp1>
1399 weak_ptr(const shared_ptr<_Tp1>& __r)
1400 : __weak_ptr<_Tp>(__r) { }
1402 template<typename _Tp1>
1404 operator=(const weak_ptr<_Tp1>& __r) // never throws
1406 this->__weak_ptr<_Tp>::operator=(__r);
1410 template<typename _Tp1>
1412 operator=(const shared_ptr<_Tp1>& __r) // never throws
1414 this->__weak_ptr<_Tp>::operator=(__r);
1419 lock() const // never throws
1422 if (this->expired())
1423 return shared_ptr<_Tp>();
1427 return shared_ptr<_Tp>(*this);
1429 __catch(const bad_weak_ptr&)
1431 return shared_ptr<_Tp>();
1434 return this->expired() ? shared_ptr<_Tp>()
1435 : shared_ptr<_Tp>(*this);
1440 template<typename _Tp1>
1441 bool operator<(const weak_ptr<_Tp1>&) const = delete;
1442 template<typename _Tp1>
1443 bool operator<=(const weak_ptr<_Tp1>&) const = delete;
1444 template<typename _Tp1>
1445 bool operator>(const weak_ptr<_Tp1>&) const = delete;
1446 template<typename _Tp1>
1447 bool operator>=(const weak_ptr<_Tp1>&) const = delete;
1450 // 20.8.13.3.7 weak_ptr specialized algorithms.
1451 template<typename _Tp>
1453 swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
1457 template<typename _Tp>
1458 struct owner_less<shared_ptr<_Tp>>
1459 : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
1462 template<typename _Tp>
1463 struct owner_less<weak_ptr<_Tp>>
1464 : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
1468 * @brief Base class allowing use of member function shared_from_this.
1470 template<typename _Tp>
1471 class enable_shared_from_this
1474 enable_shared_from_this() { }
1476 enable_shared_from_this(const enable_shared_from_this&) { }
1478 enable_shared_from_this&
1479 operator=(const enable_shared_from_this&)
1482 ~enable_shared_from_this() { }
1487 { return shared_ptr<_Tp>(this->_M_weak_this); }
1489 shared_ptr<const _Tp>
1490 shared_from_this() const
1491 { return shared_ptr<const _Tp>(this->_M_weak_this); }
1494 template<typename _Tp1>
1496 _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
1497 { _M_weak_this._M_assign(__p, __n); }
1499 template<typename _Tp1>
1501 __enable_shared_from_this_helper(const __shared_count<>& __pn,
1502 const enable_shared_from_this* __pe,
1506 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
1509 mutable weak_ptr<_Tp> _M_weak_this;
1512 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
1513 inline __shared_ptr<_Tp, _Lp>
1514 __allocate_shared(_Alloc __a, _Args&&... __args)
1516 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(),
1517 std::forward<_Alloc>(__a), std::forward<_Args>(__args)...);
1520 template<typename _Tp, _Lock_policy _Lp, typename... _Args>
1521 inline __shared_ptr<_Tp, _Lp>
1522 __make_shared(_Args&&... __args)
1524 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1525 return __allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1526 std::forward<_Args>(__args)...);
1529 /** @brief Create an object that is owned by a shared_ptr.
1530 * @param __a An allocator.
1531 * @param __args Arguments for the @a _Tp object's constructor.
1532 * @return A shared_ptr that owns the newly created object.
1533 * @throw An exception thrown from @a _Alloc::allocate or from the
1534 * constructor of @a _Tp.
1536 * A copy of @a __a will be used to allocate memory for the shared_ptr
1537 * and the new object.
1539 template<typename _Tp, typename _Alloc, typename... _Args>
1540 inline shared_ptr<_Tp>
1541 allocate_shared(_Alloc __a, _Args&&... __args)
1543 return shared_ptr<_Tp>(_Sp_make_shared_tag(), std::forward<_Alloc>(__a),
1544 std::forward<_Args>(__args)...);
1547 /** @brief Create an object that is owned by a shared_ptr.
1548 * @param __args Arguments for the @a _Tp object's constructor.
1549 * @return A shared_ptr that owns the newly created object.
1550 * @throw std::bad_alloc, or an exception thrown from the
1551 * constructor of @a _Tp.
1553 template<typename _Tp, typename... _Args>
1554 inline shared_ptr<_Tp>
1555 make_shared(_Args&&... __args)
1557 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1558 return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
1559 std::forward<_Args>(__args)...);
1562 // @} group pointer_abstractions
1564 _GLIBCXX_END_NAMESPACE
1566 #endif // _SHARED_PTR_H