1 // shared_ptr and weak_ptr implementation details -*- 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_base.h
45 * This is an internal header file, included by other library headers.
46 * Do not attempt to use it directly. @headername{memory}
49 #ifndef _SHARED_PTR_BASE_H
50 #define _SHARED_PTR_BASE_H 1
52 namespace std _GLIBCXX_VISIBILITY(default)
54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
57 * @brief Exception possibly thrown by @c shared_ptr.
60 class bad_weak_ptr : public std::exception
66 virtual ~bad_weak_ptr() throw();
69 // Substitute for bad_weak_ptr object in the case of -fno-exceptions.
71 __throw_bad_weak_ptr()
80 using __gnu_cxx::_Lock_policy;
81 using __gnu_cxx::__default_lock_policy;
82 using __gnu_cxx::_S_single;
83 using __gnu_cxx::_S_mutex;
84 using __gnu_cxx::_S_atomic;
86 // Empty helper class except when the template argument is _S_mutex.
87 template<_Lock_policy _Lp>
91 // The atomic policy uses fully-fenced builtins, single doesn't care.
92 enum { _S_need_barriers = 0 };
96 class _Mutex_base<_S_mutex>
97 : public __gnu_cxx::__mutex
100 // This policy is used when atomic builtins are not available.
101 // The replacement atomic operations might not have the necessary
103 enum { _S_need_barriers = 1 };
106 template<_Lock_policy _Lp = __default_lock_policy>
107 class _Sp_counted_base
108 : public _Mutex_base<_Lp>
112 : _M_use_count(1), _M_weak_count(1) { }
115 ~_Sp_counted_base() // nothrow
118 // Called when _M_use_count drops to zero, to release the resources
121 _M_dispose() = 0; // nothrow
123 // Called when _M_weak_count drops to zero.
125 _M_destroy() // nothrow
129 _M_get_deleter(const std::type_info&) = 0;
133 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
139 _M_release() // nothrow
141 // Be race-detector-friendly. For more info see bits/c++config.
142 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
143 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
145 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
147 // There must be a memory barrier between dispose() and destroy()
148 // to ensure that the effects of dispose() are observed in the
149 // thread that runs destroy().
150 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
151 if (_Mutex_base<_Lp>::_S_need_barriers)
153 _GLIBCXX_READ_MEM_BARRIER;
154 _GLIBCXX_WRITE_MEM_BARRIER;
157 // Be race-detector-friendly. For more info see bits/c++config.
158 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
159 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
162 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
169 _M_weak_add_ref() // nothrow
170 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
173 _M_weak_release() // nothrow
175 // Be race-detector-friendly. For more info see bits/c++config.
176 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
177 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
179 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
180 if (_Mutex_base<_Lp>::_S_need_barriers)
183 // destroy() must observe results of dispose()
184 _GLIBCXX_READ_MEM_BARRIER;
185 _GLIBCXX_WRITE_MEM_BARRIER;
192 _M_get_use_count() const // nothrow
194 // No memory barrier is used here so there is no synchronization
195 // with other threads.
196 return const_cast<const volatile _Atomic_word&>(_M_use_count);
200 _Sp_counted_base(_Sp_counted_base const&);
201 _Sp_counted_base& operator=(_Sp_counted_base const&);
203 _Atomic_word _M_use_count; // #shared
204 _Atomic_word _M_weak_count; // #weak + (#shared != 0)
209 _Sp_counted_base<_S_single>::
212 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
215 __throw_bad_weak_ptr();
221 _Sp_counted_base<_S_mutex>::
224 __gnu_cxx::__scoped_lock sentry(*this);
225 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
228 __throw_bad_weak_ptr();
234 _Sp_counted_base<_S_atomic>::
237 // Perform lock-free add-if-not-zero operation.
238 _Atomic_word __count;
241 __count = _M_use_count;
243 __throw_bad_weak_ptr();
245 // Replace the current counter value with the old value + 1, as
246 // long as it's not changed meanwhile.
248 while (!__sync_bool_compare_and_swap(&_M_use_count, __count,
253 // Forward declarations.
254 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
257 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
260 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
261 class __enable_shared_from_this;
263 template<typename _Tp>
266 template<typename _Tp>
269 template<typename _Tp>
272 template<typename _Tp>
273 class enable_shared_from_this;
275 template<_Lock_policy _Lp = __default_lock_policy>
278 template<_Lock_policy _Lp = __default_lock_policy>
279 class __shared_count;
282 // Counted ptr with no deleter or allocator support
283 template<typename _Ptr, _Lock_policy _Lp>
284 class _Sp_counted_ptr : public _Sp_counted_base<_Lp>
288 _Sp_counted_ptr(_Ptr __p)
292 _M_dispose() // nothrow
296 _M_destroy() // nothrow
300 _M_get_deleter(const std::type_info&)
303 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
304 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
307 _Ptr _M_ptr; // copy constructor must not throw
312 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() { }
316 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() { }
320 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() { }
322 // Support for custom deleter and/or allocator
323 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
324 class _Sp_counted_deleter : public _Sp_counted_base<_Lp>
326 typedef typename _Alloc::template
327 rebind<_Sp_counted_deleter>::other _My_alloc_type;
329 // Helper class that stores the Deleter and also acts as an allocator.
330 // Used to dispose of the owned pointer and the internal refcount
331 // Requires that copies of _Alloc can free each other's memory.
333 : public _My_alloc_type // copy constructor must not throw
335 _Deleter _M_del; // copy constructor must not throw
336 _My_Deleter(_Deleter __d, const _Alloc& __a)
337 : _My_alloc_type(__a), _M_del(__d) { }
341 // __d(__p) must not throw.
342 _Sp_counted_deleter(_Ptr __p, _Deleter __d)
343 : _M_ptr(__p), _M_del(__d, _Alloc()) { }
345 // __d(__p) must not throw.
346 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a)
347 : _M_ptr(__p), _M_del(__d, __a) { }
350 _M_dispose() // nothrow
351 { _M_del._M_del(_M_ptr); }
354 _M_destroy() // nothrow
356 _My_alloc_type __a(_M_del);
357 this->~_Sp_counted_deleter();
358 __a.deallocate(this, 1);
362 _M_get_deleter(const std::type_info& __ti)
365 return __ti == typeid(_Deleter) ? &_M_del._M_del : 0;
372 _Ptr _M_ptr; // copy constructor must not throw
373 _My_Deleter _M_del; // copy constructor must not throw
376 // helpers for make_shared / allocate_shared
378 template<typename _Tp>
379 struct _Sp_destroy_inplace
381 void operator()(_Tp* __p) const { if (__p) __p->~_Tp(); }
384 struct _Sp_make_shared_tag { };
386 template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
387 class _Sp_counted_ptr_inplace
388 : public _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp>
390 typedef _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp>
395 _Sp_counted_ptr_inplace(_Alloc __a)
396 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a)
399 void* __p = &_M_storage;
400 ::new (__p) _Tp(); // might throw
401 _Base_type::_M_ptr = static_cast<_Tp*>(__p);
404 template<typename... _Args>
405 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
406 : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a)
409 void* __p = &_M_storage;
410 ::new (__p) _Tp(std::forward<_Args>(__args)...); // might throw
411 _Base_type::_M_ptr = static_cast<_Tp*>(__p);
414 // Override because the allocator needs to know the dynamic type
416 _M_destroy() // nothrow
418 typedef typename _Alloc::template
419 rebind<_Sp_counted_ptr_inplace>::other _My_alloc_type;
420 _My_alloc_type __a(_Base_type::_M_del);
421 this->~_Sp_counted_ptr_inplace();
422 __a.deallocate(this, 1);
425 // Sneaky trick so __shared_ptr can get the managed pointer
427 _M_get_deleter(const std::type_info& __ti)
430 return __ti == typeid(_Sp_make_shared_tag)
431 ? static_cast<void*>(&_M_storage)
432 : _Base_type::_M_get_deleter(__ti);
439 typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type
443 template<_Lock_policy _Lp>
447 constexpr __shared_count() : _M_pi(0) // nothrow
450 template<typename _Ptr>
452 __shared_count(_Ptr __p) : _M_pi(0)
456 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
461 __throw_exception_again;
465 template<typename _Ptr, typename _Deleter>
466 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0)
468 // The allocator's value_type doesn't matter, will rebind it anyway.
469 typedef std::allocator<int> _Alloc;
470 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
471 typedef std::allocator<_Sp_cd_type> _Alloc2;
475 _M_pi = __a2.allocate(1);
476 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d);
480 __d(__p); // Call _Deleter on __p.
482 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1);
483 __throw_exception_again;
487 template<typename _Ptr, typename _Deleter, typename _Alloc>
488 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
490 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
491 typedef typename _Alloc::template rebind<_Sp_cd_type>::other _Alloc2;
495 _M_pi = __a2.allocate(1);
496 ::new(static_cast<void*>(_M_pi)) _Sp_cd_type(__p, __d, __a);
500 __d(__p); // Call _Deleter on __p.
502 __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1);
503 __throw_exception_again;
507 template<typename _Tp, typename _Alloc, typename... _Args>
508 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a,
512 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
513 typedef typename _Alloc::template rebind<_Sp_cp_type>::other _Alloc2;
517 _M_pi = __a2.allocate(1);
518 ::new(static_cast<void*>(_M_pi)) _Sp_cp_type(__a,
519 std::forward<_Args>(__args)...);
524 __a2.deallocate(static_cast<_Sp_cp_type*>(_M_pi), 1);
525 __throw_exception_again;
529 #if _GLIBCXX_USE_DEPRECATED
530 // Special case for auto_ptr<_Tp> to provide the strong guarantee.
531 template<typename _Tp>
533 __shared_count(std::auto_ptr<_Tp>&& __r)
534 : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get()))
538 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
539 template<typename _Tp, typename _Del>
541 __shared_count(std::unique_ptr<_Tp, _Del>&& __r)
542 : _M_pi(_S_create_from_up(std::move(__r)))
545 // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
546 explicit __shared_count(const __weak_count<_Lp>& __r);
548 ~__shared_count() // nothrow
554 __shared_count(const __shared_count& __r)
555 : _M_pi(__r._M_pi) // nothrow
558 _M_pi->_M_add_ref_copy();
562 operator=(const __shared_count& __r) // nothrow
564 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
568 __tmp->_M_add_ref_copy();
577 _M_swap(__shared_count& __r) // nothrow
579 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
585 _M_get_use_count() const // nothrow
586 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
589 _M_unique() const // nothrow
590 { return this->_M_get_use_count() == 1; }
593 _M_get_deleter(const std::type_info& __ti) const
594 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; }
597 _M_less(const __shared_count& __rhs) const
598 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
601 _M_less(const __weak_count<_Lp>& __rhs) const
602 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
604 // Friend function injected into enclosing namespace and found by ADL
606 operator==(const __shared_count& __a, const __shared_count& __b)
607 { return __a._M_pi == __b._M_pi; }
610 friend class __weak_count<_Lp>;
612 template<typename _Tp, typename _Del>
613 static _Sp_counted_base<_Lp>*
614 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
615 typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0)
617 return new _Sp_counted_deleter<_Tp*, _Del, std::allocator<_Tp>,
618 _Lp>(__r.get(), __r.get_deleter());
621 template<typename _Tp, typename _Del>
622 static _Sp_counted_base<_Lp>*
623 _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
624 typename std::enable_if<std::is_reference<_Del>::value>::type* = 0)
626 typedef typename std::remove_reference<_Del>::type _Del1;
627 typedef std::reference_wrapper<_Del1> _Del2;
628 return new _Sp_counted_deleter<_Tp*, _Del2, std::allocator<_Tp>,
629 _Lp>(__r.get(), std::ref(__r.get_deleter()));
632 _Sp_counted_base<_Lp>* _M_pi;
636 template<_Lock_policy _Lp>
640 constexpr __weak_count() : _M_pi(0) // nothrow
643 __weak_count(const __shared_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow
646 _M_pi->_M_weak_add_ref();
649 __weak_count(const __weak_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow
652 _M_pi->_M_weak_add_ref();
655 ~__weak_count() // nothrow
658 _M_pi->_M_weak_release();
662 operator=(const __shared_count<_Lp>& __r) // nothrow
664 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
666 __tmp->_M_weak_add_ref();
668 _M_pi->_M_weak_release();
674 operator=(const __weak_count<_Lp>& __r) // nothrow
676 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
678 __tmp->_M_weak_add_ref();
680 _M_pi->_M_weak_release();
686 _M_swap(__weak_count<_Lp>& __r) // nothrow
688 _Sp_counted_base<_Lp>* __tmp = __r._M_pi;
694 _M_get_use_count() const // nothrow
695 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
698 _M_less(const __weak_count& __rhs) const
699 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
702 _M_less(const __shared_count<_Lp>& __rhs) const
703 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
705 // Friend function injected into enclosing namespace and found by ADL
707 operator==(const __weak_count& __a, const __weak_count& __b)
708 { return __a._M_pi == __b._M_pi; }
711 friend class __shared_count<_Lp>;
713 _Sp_counted_base<_Lp>* _M_pi;
716 // Now that __weak_count is defined we can define this constructor:
717 template<_Lock_policy _Lp>
718 inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r)
722 _M_pi->_M_add_ref_lock();
724 __throw_bad_weak_ptr();
728 // Support for enable_shared_from_this.
730 // Friend of __enable_shared_from_this.
731 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2>
733 __enable_shared_from_this_helper(const __shared_count<_Lp>&,
734 const __enable_shared_from_this<_Tp1,
737 // Friend of enable_shared_from_this.
738 template<typename _Tp1, typename _Tp2>
740 __enable_shared_from_this_helper(const __shared_count<>&,
741 const enable_shared_from_this<_Tp1>*,
744 template<_Lock_policy _Lp>
746 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...)
750 template<typename _Tp, _Lock_policy _Lp>
754 typedef _Tp element_type;
756 constexpr __shared_ptr()
757 : _M_ptr(0), _M_refcount() // never throws
760 template<typename _Tp1>
761 explicit __shared_ptr(_Tp1* __p)
762 : _M_ptr(__p), _M_refcount(__p)
764 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
765 static_assert( sizeof(_Tp1) > 0, "incomplete type" );
766 __enable_shared_from_this_helper(_M_refcount, __p, __p);
769 template<typename _Tp1, typename _Deleter>
770 __shared_ptr(_Tp1* __p, _Deleter __d)
771 : _M_ptr(__p), _M_refcount(__p, __d)
773 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
774 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
775 __enable_shared_from_this_helper(_M_refcount, __p, __p);
778 template<typename _Tp1, typename _Deleter, typename _Alloc>
779 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
780 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a))
782 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
783 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed
784 __enable_shared_from_this_helper(_M_refcount, __p, __p);
787 template<typename _Deleter>
788 __shared_ptr(nullptr_t __p, _Deleter __d)
789 : _M_ptr(0), _M_refcount(__p, __d)
792 template<typename _Deleter, typename _Alloc>
793 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
794 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a))
797 template<typename _Tp1>
798 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p)
799 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
802 // generated copy constructor, assignment, destructor are fine.
804 template<typename _Tp1, typename = typename
805 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
806 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
807 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
810 __shared_ptr(__shared_ptr&& __r)
811 : _M_ptr(__r._M_ptr), _M_refcount() // never throws
813 _M_refcount._M_swap(__r._M_refcount);
817 template<typename _Tp1, typename = typename
818 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
819 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r)
820 : _M_ptr(__r._M_ptr), _M_refcount() // never throws
822 _M_refcount._M_swap(__r._M_refcount);
826 template<typename _Tp1>
827 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
828 : _M_refcount(__r._M_refcount) // may throw
830 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
832 // It is now safe to copy __r._M_ptr, as
833 // _M_refcount(__r._M_refcount) did not throw.
837 // If an exception is thrown this constructor has no effect.
838 template<typename _Tp1, typename _Del>
839 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
840 : _M_ptr(__r.get()), _M_refcount()
842 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
843 _Tp1* __tmp = __r.get();
844 _M_refcount = __shared_count<_Lp>(std::move(__r));
845 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
848 #if _GLIBCXX_USE_DEPRECATED
849 // Postcondition: use_count() == 1 and __r.get() == 0
850 template<typename _Tp1>
851 __shared_ptr(std::auto_ptr<_Tp1>&& __r)
852 : _M_ptr(__r.get()), _M_refcount()
854 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
855 static_assert( sizeof(_Tp1) > 0, "incomplete type" );
856 _Tp1* __tmp = __r.get();
857 _M_refcount = __shared_count<_Lp>(std::move(__r));
858 __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
862 /* TODO: use delegating constructor */
863 constexpr __shared_ptr(nullptr_t)
864 : _M_ptr(0), _M_refcount() // never throws
867 template<typename _Tp1>
869 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
872 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
876 #if _GLIBCXX_USE_DEPRECATED
877 template<typename _Tp1>
879 operator=(std::auto_ptr<_Tp1>&& __r)
881 __shared_ptr(std::move(__r)).swap(*this);
887 operator=(__shared_ptr&& __r)
889 __shared_ptr(std::move(__r)).swap(*this);
895 operator=(__shared_ptr<_Tp1, _Lp>&& __r)
897 __shared_ptr(std::move(__r)).swap(*this);
901 template<typename _Tp1, typename _Del>
903 operator=(std::unique_ptr<_Tp1, _Del>&& __r)
905 __shared_ptr(std::move(__r)).swap(*this);
910 reset() // never throws
911 { __shared_ptr().swap(*this); }
913 template<typename _Tp1>
915 reset(_Tp1* __p) // _Tp1 must be complete.
917 // Catch self-reset errors.
918 _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr);
919 __shared_ptr(__p).swap(*this);
922 template<typename _Tp1, typename _Deleter>
924 reset(_Tp1* __p, _Deleter __d)
925 { __shared_ptr(__p, __d).swap(*this); }
927 template<typename _Tp1, typename _Deleter, typename _Alloc>
929 reset(_Tp1* __p, _Deleter __d, _Alloc __a)
930 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); }
932 // Allow class instantiation when _Tp is [cv-qual] void.
933 typename std::add_lvalue_reference<_Tp>::type
934 operator*() const // never throws
936 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
941 operator->() const // never throws
943 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
948 get() const // never throws
951 explicit operator bool() const // never throws
952 { return _M_ptr == 0 ? false : true; }
955 unique() const // never throws
956 { return _M_refcount._M_unique(); }
959 use_count() const // never throws
960 { return _M_refcount._M_get_use_count(); }
963 swap(__shared_ptr<_Tp, _Lp>& __other) // never throws
965 std::swap(_M_ptr, __other._M_ptr);
966 _M_refcount._M_swap(__other._M_refcount);
969 template<typename _Tp1>
971 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const
972 { return _M_refcount._M_less(__rhs._M_refcount); }
974 template<typename _Tp1>
976 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const
977 { return _M_refcount._M_less(__rhs._M_refcount); }
981 // This constructor is non-standard, it is used by allocate_shared.
982 template<typename _Alloc, typename... _Args>
983 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
985 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
986 std::forward<_Args>(__args)...)
988 // _M_ptr needs to point to the newly constructed object.
989 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
990 void* __p = _M_refcount._M_get_deleter(typeid(__tag));
991 _M_ptr = static_cast<_Tp*>(__p);
992 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
995 template<typename _Alloc>
998 void operator()(_Tp* __ptr)
1000 _M_alloc.destroy(__ptr);
1001 _M_alloc.deallocate(__ptr, 1);
1006 template<typename _Alloc, typename... _Args>
1007 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
1009 : _M_ptr(), _M_refcount()
1011 typedef typename _Alloc::template rebind<_Tp>::other _Alloc2;
1012 _Deleter<_Alloc2> __del = { _Alloc2(__a) };
1013 _M_ptr = __del._M_alloc.allocate(1);
1016 __del._M_alloc.construct(_M_ptr, std::forward<_Args>(__args)...);
1020 __del._M_alloc.deallocate(_M_ptr, 1);
1021 __throw_exception_again;
1023 __shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc);
1024 _M_refcount._M_swap(__count);
1025 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
1029 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
1031 friend __shared_ptr<_Tp1, _Lp1>
1032 __allocate_shared(const _Alloc& __a, _Args&&... __args);
1036 _M_get_deleter(const std::type_info& __ti) const
1037 { return _M_refcount._M_get_deleter(__ti); }
1039 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1040 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1042 template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
1043 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&);
1045 _Tp* _M_ptr; // Contained pointer.
1046 __shared_count<_Lp> _M_refcount; // Reference counter.
1050 // 20.8.13.2.7 shared_ptr comparisons
1051 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1053 operator==(const __shared_ptr<_Tp1, _Lp>& __a,
1054 const __shared_ptr<_Tp2, _Lp>& __b)
1055 { return __a.get() == __b.get(); }
1057 template<typename _Tp, _Lock_policy _Lp>
1059 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t)
1060 { return __a.get() == nullptr; }
1062 template<typename _Tp, _Lock_policy _Lp>
1064 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b)
1065 { return nullptr == __b.get(); }
1067 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1069 operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
1070 const __shared_ptr<_Tp2, _Lp>& __b)
1071 { return __a.get() != __b.get(); }
1073 template<typename _Tp, _Lock_policy _Lp>
1075 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t)
1076 { return __a.get() != nullptr; }
1078 template<typename _Tp, _Lock_policy _Lp>
1080 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b)
1081 { return nullptr != __b.get(); }
1083 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
1085 operator<(const __shared_ptr<_Tp1, _Lp>& __a,
1086 const __shared_ptr<_Tp2, _Lp>& __b)
1087 { return __a.get() < __b.get(); }
1089 template<typename _Sp>
1090 struct _Sp_less : public binary_function<_Sp, _Sp, bool>
1093 operator()(const _Sp& __lhs, const _Sp& __rhs) const
1095 typedef typename _Sp::element_type element_type;
1096 return std::less<element_type*>()(__lhs.get(), __rhs.get());
1100 template<typename _Tp, _Lock_policy _Lp>
1101 struct less<__shared_ptr<_Tp, _Lp>>
1102 : public _Sp_less<__shared_ptr<_Tp, _Lp>>
1105 // 2.2.3.8 shared_ptr specialized algorithms.
1106 template<typename _Tp, _Lock_policy _Lp>
1108 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b)
1111 // 2.2.3.9 shared_ptr casts
1113 // The seemingly equivalent code:
1114 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
1115 // will eventually result in undefined behaviour, attempting to
1116 // delete the same object twice.
1117 /// static_pointer_cast
1118 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1119 inline __shared_ptr<_Tp, _Lp>
1120 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
1121 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); }
1123 // The seemingly equivalent code:
1124 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
1125 // will eventually result in undefined behaviour, attempting to
1126 // delete the same object twice.
1127 /// const_pointer_cast
1128 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1129 inline __shared_ptr<_Tp, _Lp>
1130 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
1131 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); }
1133 // The seemingly equivalent code:
1134 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
1135 // will eventually result in undefined behaviour, attempting to
1136 // delete the same object twice.
1137 /// dynamic_pointer_cast
1138 template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
1139 inline __shared_ptr<_Tp, _Lp>
1140 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r)
1142 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
1143 return __shared_ptr<_Tp, _Lp>(__r, __p);
1144 return __shared_ptr<_Tp, _Lp>();
1148 template<typename _Tp, _Lock_policy _Lp>
1152 typedef _Tp element_type;
1154 constexpr __weak_ptr()
1155 : _M_ptr(0), _M_refcount() // never throws
1158 // Generated copy constructor, assignment, destructor are fine.
1160 // The "obvious" converting constructor implementation:
1162 // template<typename _Tp1>
1163 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1164 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1167 // has a serious problem.
1169 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
1170 // conversion may require access to *__r._M_ptr (virtual inheritance).
1172 // It is not possible to avoid spurious access violations since
1173 // in multithreaded programs __r._M_ptr may be invalidated at any point.
1174 template<typename _Tp1, typename = typename
1175 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
1176 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
1177 : _M_refcount(__r._M_refcount) // never throws
1178 { _M_ptr = __r.lock().get(); }
1180 template<typename _Tp1, typename = typename
1181 std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
1182 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r)
1183 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
1186 template<typename _Tp1>
1188 operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws
1190 _M_ptr = __r.lock().get();
1191 _M_refcount = __r._M_refcount;
1195 template<typename _Tp1>
1197 operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws
1199 _M_ptr = __r._M_ptr;
1200 _M_refcount = __r._M_refcount;
1204 __shared_ptr<_Tp, _Lp>
1205 lock() const // never throws
1208 // Optimization: avoid throw overhead.
1210 return __shared_ptr<element_type, _Lp>();
1214 return __shared_ptr<element_type, _Lp>(*this);
1216 __catch(const bad_weak_ptr&)
1218 // Q: How can we get here?
1219 // A: Another thread may have invalidated r after the
1220 // use_count test above.
1221 return __shared_ptr<element_type, _Lp>();
1225 // Optimization: avoid try/catch overhead when single threaded.
1226 return expired() ? __shared_ptr<element_type, _Lp>()
1227 : __shared_ptr<element_type, _Lp>(*this);
1233 use_count() const // never throws
1234 { return _M_refcount._M_get_use_count(); }
1237 expired() const // never throws
1238 { return _M_refcount._M_get_use_count() == 0; }
1240 template<typename _Tp1>
1242 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const
1243 { return _M_refcount._M_less(__rhs._M_refcount); }
1245 template<typename _Tp1>
1247 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const
1248 { return _M_refcount._M_less(__rhs._M_refcount); }
1251 reset() // never throws
1252 { __weak_ptr().swap(*this); }
1255 swap(__weak_ptr& __s) // never throws
1257 std::swap(_M_ptr, __s._M_ptr);
1258 _M_refcount._M_swap(__s._M_refcount);
1262 // Used by __enable_shared_from_this.
1264 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount)
1267 _M_refcount = __refcount;
1270 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
1271 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
1272 friend class __enable_shared_from_this<_Tp, _Lp>;
1273 friend class enable_shared_from_this<_Tp>;
1275 _Tp* _M_ptr; // Contained pointer.
1276 __weak_count<_Lp> _M_refcount; // Reference counter.
1279 // 20.8.13.3.7 weak_ptr specialized algorithms.
1280 template<typename _Tp, _Lock_policy _Lp>
1282 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b)
1285 template<typename _Tp, typename _Tp1>
1286 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
1289 operator()(const _Tp& __lhs, const _Tp& __rhs) const
1290 { return __lhs.owner_before(__rhs); }
1293 operator()(const _Tp& __lhs, const _Tp1& __rhs) const
1294 { return __lhs.owner_before(__rhs); }
1297 operator()(const _Tp1& __lhs, const _Tp& __rhs) const
1298 { return __lhs.owner_before(__rhs); }
1301 template<typename _Tp, _Lock_policy _Lp>
1302 struct owner_less<__shared_ptr<_Tp, _Lp>>
1303 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
1306 template<typename _Tp, _Lock_policy _Lp>
1307 struct owner_less<__weak_ptr<_Tp, _Lp>>
1308 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
1312 template<typename _Tp, _Lock_policy _Lp>
1313 class __enable_shared_from_this
1316 constexpr __enable_shared_from_this() { }
1318 __enable_shared_from_this(const __enable_shared_from_this&) { }
1320 __enable_shared_from_this&
1321 operator=(const __enable_shared_from_this&)
1324 ~__enable_shared_from_this() { }
1327 __shared_ptr<_Tp, _Lp>
1329 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
1331 __shared_ptr<const _Tp, _Lp>
1332 shared_from_this() const
1333 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
1336 template<typename _Tp1>
1338 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const
1339 { _M_weak_this._M_assign(__p, __n); }
1341 template<typename _Tp1>
1343 __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn,
1344 const __enable_shared_from_this* __pe,
1348 __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
1351 mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
1355 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
1356 inline __shared_ptr<_Tp, _Lp>
1357 __allocate_shared(const _Alloc& __a, _Args&&... __args)
1359 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a,
1360 std::forward<_Args>(__args)...);
1363 template<typename _Tp, _Lock_policy _Lp, typename... _Args>
1364 inline __shared_ptr<_Tp, _Lp>
1365 __make_shared(_Args&&... __args)
1367 typedef typename std::remove_const<_Tp>::type _Tp_nc;
1368 return __allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
1369 std::forward<_Args>(__args)...);
1372 /// std::hash specialization for __shared_ptr.
1373 template<typename _Tp, _Lock_policy _Lp>
1374 struct hash<__shared_ptr<_Tp, _Lp>>
1375 : public std::unary_function<__shared_ptr<_Tp, _Lp>, size_t>
1378 operator()(const __shared_ptr<_Tp, _Lp>& __s) const
1379 { return std::hash<_Tp*>()(__s.get()); }
1382 _GLIBCXX_END_NAMESPACE_VERSION
1385 #endif // _SHARED_PTR_BASE_H