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922 lines
30 KiB
922 lines
30 KiB
// shared_ptr and weak_ptr implementation -*- C++ -*-
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// Copyright (C) 2007-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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// GCC Note: Based on files from version 1.32.0 of the Boost library.
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// shared_count.hpp
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// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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// shared_ptr.hpp
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// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
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// Copyright (C) 2001, 2002, 2003 Peter Dimov
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// weak_ptr.hpp
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// Copyright (C) 2001, 2002, 2003 Peter Dimov
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// enable_shared_from_this.hpp
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// Copyright (C) 2002 Peter Dimov
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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/** @file
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{memory}
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*/
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#ifndef _SHARED_PTR_H
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#define _SHARED_PTR_H 1
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#include <iosfwd> // std::basic_ostream
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#include <bits/shared_ptr_base.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @addtogroup pointer_abstractions
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* @{
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*/
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// 20.7.2.2.11 shared_ptr I/O
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/// Write the stored pointer to an ostream.
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/// @relates shared_ptr
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template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
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inline std::basic_ostream<_Ch, _Tr>&
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operator<<(std::basic_ostream<_Ch, _Tr>& __os,
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const __shared_ptr<_Tp, _Lp>& __p)
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{
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__os << __p.get();
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return __os;
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}
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template<typename _Del, typename _Tp, _Lock_policy _Lp>
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inline _Del*
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get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
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{
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#if __cpp_rtti
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return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
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#else
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return 0;
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#endif
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}
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/// 20.7.2.2.10 shared_ptr get_deleter
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/// If `__p` has a deleter of type `_Del`, return a pointer to it.
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/// @relates shared_ptr
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template<typename _Del, typename _Tp>
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inline _Del*
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get_deleter(const shared_ptr<_Tp>& __p) noexcept
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{
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#if __cpp_rtti
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return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
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#else
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return 0;
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#endif
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}
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/**
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* @brief A smart pointer with reference-counted copy semantics.
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*
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* A `shared_ptr` object is either empty or _owns_ a pointer passed
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* to the constructor. Copies of a `shared_ptr` share ownership of
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* the same pointer. When the last `shared_ptr` that owns the pointer
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* is destroyed or reset, the owned pointer is freed (either by `delete`
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* or by invoking a custom deleter that was passed to the constructor).
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*
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* A `shared_ptr` also stores another pointer, which is usually
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* (but not always) the same pointer as it owns. The stored pointer
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* can be retrieved by calling the `get()` member function.
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*
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* The equality and relational operators for `shared_ptr` only compare
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* the stored pointer returned by `get()`, not the owned pointer.
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* To test whether two `shared_ptr` objects share ownership of the same
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* pointer see `std::shared_ptr::owner_before` and `std::owner_less`.
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*/
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template<typename _Tp>
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class shared_ptr : public __shared_ptr<_Tp>
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{
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template<typename... _Args>
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using _Constructible = typename enable_if<
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is_constructible<__shared_ptr<_Tp>, _Args...>::value
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>::type;
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template<typename _Arg>
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using _Assignable = typename enable_if<
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is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr&
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>::type;
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public:
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/// The type pointed to by the stored pointer, remove_extent_t<_Tp>
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using element_type = typename __shared_ptr<_Tp>::element_type;
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#if __cplusplus >= 201703L
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# define __cpp_lib_shared_ptr_weak_type 201606
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/// The corresponding weak_ptr type for this shared_ptr
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using weak_type = weak_ptr<_Tp>;
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#endif
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/**
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* @brief Construct an empty %shared_ptr.
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* @post use_count()==0 && get()==0
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*/
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constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }
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shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor
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/**
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* @brief Construct a %shared_ptr that owns the pointer @a __p.
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* @param __p A pointer that is convertible to element_type*.
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* @post use_count() == 1 && get() == __p
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* @throw std::bad_alloc, in which case @c delete @a __p is called.
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*/
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template<typename _Yp, typename = _Constructible<_Yp*>>
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explicit
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shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { }
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/**
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* @brief Construct a %shared_ptr that owns the pointer @a __p
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* and the deleter @a __d.
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* @param __p A pointer.
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* @param __d A deleter.
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* @post use_count() == 1 && get() == __p
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* @throw std::bad_alloc, in which case @a __d(__p) is called.
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*
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* Requirements: _Deleter's copy constructor and destructor must
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* not throw
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*
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* __shared_ptr will release __p by calling __d(__p)
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*/
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template<typename _Yp, typename _Deleter,
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typename = _Constructible<_Yp*, _Deleter>>
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shared_ptr(_Yp* __p, _Deleter __d)
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: __shared_ptr<_Tp>(__p, std::move(__d)) { }
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/**
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* @brief Construct a %shared_ptr that owns a null pointer
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* and the deleter @a __d.
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* @param __p A null pointer constant.
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* @param __d A deleter.
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* @post use_count() == 1 && get() == __p
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* @throw std::bad_alloc, in which case @a __d(__p) is called.
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*
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* Requirements: _Deleter's copy constructor and destructor must
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* not throw
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*
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* The last owner will call __d(__p)
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*/
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template<typename _Deleter>
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shared_ptr(nullptr_t __p, _Deleter __d)
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: __shared_ptr<_Tp>(__p, std::move(__d)) { }
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/**
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* @brief Construct a %shared_ptr that owns the pointer @a __p
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* and the deleter @a __d.
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* @param __p A pointer.
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* @param __d A deleter.
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* @param __a An allocator.
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* @post use_count() == 1 && get() == __p
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* @throw std::bad_alloc, in which case @a __d(__p) is called.
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*
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* Requirements: _Deleter's copy constructor and destructor must
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* not throw _Alloc's copy constructor and destructor must not
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* throw.
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*
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* __shared_ptr will release __p by calling __d(__p)
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*/
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template<typename _Yp, typename _Deleter, typename _Alloc,
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typename = _Constructible<_Yp*, _Deleter, _Alloc>>
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shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
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: __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
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/**
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* @brief Construct a %shared_ptr that owns a null pointer
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* and the deleter @a __d.
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* @param __p A null pointer constant.
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* @param __d A deleter.
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* @param __a An allocator.
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* @post use_count() == 1 && get() == __p
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* @throw std::bad_alloc, in which case @a __d(__p) is called.
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*
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* Requirements: _Deleter's copy constructor and destructor must
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* not throw _Alloc's copy constructor and destructor must not
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* throw.
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*
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* The last owner will call __d(__p)
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*/
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template<typename _Deleter, typename _Alloc>
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shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
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: __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }
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// Aliasing constructor
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/**
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* @brief Constructs a `shared_ptr` instance that stores `__p`
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* and shares ownership with `__r`.
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* @param __r A `shared_ptr`.
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* @param __p A pointer that will remain valid while `*__r` is valid.
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* @post `get() == __p && use_count() == __r.use_count()`
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*
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* This can be used to construct a `shared_ptr` to a sub-object
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* of an object managed by an existing `shared_ptr`. The complete
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* object will remain valid while any `shared_ptr` owns it, even
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* if they don't store a pointer to the complete object.
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*
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* @code
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* shared_ptr<pair<int,int>> pii(new pair<int,int>());
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* shared_ptr<int> pi(pii, &pii->first);
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* assert(pii.use_count() == 2);
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* @endcode
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*/
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template<typename _Yp>
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shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
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: __shared_ptr<_Tp>(__r, __p) { }
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#if __cplusplus > 201703L
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2996. Missing rvalue overloads for shared_ptr operations
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/**
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* @brief Constructs a `shared_ptr` instance that stores `__p`
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* and shares ownership with `__r`.
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* @param __r A `shared_ptr`.
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* @param __p A pointer that will remain valid while `*__r` is valid.
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* @post `get() == __p && !__r.use_count() && !__r.get()`
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*
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* This can be used to construct a `shared_ptr` to a sub-object
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* of an object managed by an existing `shared_ptr`. The complete
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* object will remain valid while any `shared_ptr` owns it, even
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* if they don't store a pointer to the complete object.
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*
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* @code
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* shared_ptr<pair<int,int>> pii(new pair<int,int>());
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* shared_ptr<int> pi1(pii, &pii->first);
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* assert(pii.use_count() == 2);
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* shared_ptr<int> pi2(std::move(pii), &pii->second);
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* assert(pii.use_count() == 0);
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* @endcode
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*/
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template<typename _Yp>
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shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept
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: __shared_ptr<_Tp>(std::move(__r), __p) { }
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#endif
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/**
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* @brief If @a __r is empty, constructs an empty %shared_ptr;
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* otherwise construct a %shared_ptr that shares ownership
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* with @a __r.
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* @param __r A %shared_ptr.
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* @post get() == __r.get() && use_count() == __r.use_count()
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*/
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template<typename _Yp,
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typename = _Constructible<const shared_ptr<_Yp>&>>
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shared_ptr(const shared_ptr<_Yp>& __r) noexcept
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: __shared_ptr<_Tp>(__r) { }
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/**
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* @brief Move-constructs a %shared_ptr instance from @a __r.
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* @param __r A %shared_ptr rvalue.
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* @post *this contains the old value of @a __r, @a __r is empty.
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*/
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shared_ptr(shared_ptr&& __r) noexcept
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: __shared_ptr<_Tp>(std::move(__r)) { }
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/**
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* @brief Move-constructs a %shared_ptr instance from @a __r.
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* @param __r A %shared_ptr rvalue.
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* @post *this contains the old value of @a __r, @a __r is empty.
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*/
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template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
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shared_ptr(shared_ptr<_Yp>&& __r) noexcept
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: __shared_ptr<_Tp>(std::move(__r)) { }
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/**
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* @brief Constructs a %shared_ptr that shares ownership with @a __r
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* and stores a copy of the pointer stored in @a __r.
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* @param __r A weak_ptr.
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* @post use_count() == __r.use_count()
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* @throw bad_weak_ptr when __r.expired(),
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* in which case the constructor has no effect.
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*/
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template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
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explicit shared_ptr(const weak_ptr<_Yp>& __r)
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: __shared_ptr<_Tp>(__r) { }
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#if _GLIBCXX_USE_DEPRECATED
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
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template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
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shared_ptr(auto_ptr<_Yp>&& __r);
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#pragma GCC diagnostic pop
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#endif
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2399. shared_ptr's constructor from unique_ptr should be constrained
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template<typename _Yp, typename _Del,
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typename = _Constructible<unique_ptr<_Yp, _Del>>>
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shared_ptr(unique_ptr<_Yp, _Del>&& __r)
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: __shared_ptr<_Tp>(std::move(__r)) { }
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#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
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// This non-standard constructor exists to support conversions that
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// were possible in C++11 and C++14 but are ill-formed in C++17.
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// If an exception is thrown this constructor has no effect.
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template<typename _Yp, typename _Del,
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_Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0>
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shared_ptr(unique_ptr<_Yp, _Del>&& __r)
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: __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { }
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#endif
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/**
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* @brief Construct an empty %shared_ptr.
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* @post use_count() == 0 && get() == nullptr
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*/
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constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }
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shared_ptr& operator=(const shared_ptr&) noexcept = default;
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template<typename _Yp>
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_Assignable<const shared_ptr<_Yp>&>
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operator=(const shared_ptr<_Yp>& __r) noexcept
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{
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this->__shared_ptr<_Tp>::operator=(__r);
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return *this;
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}
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#if _GLIBCXX_USE_DEPRECATED
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
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template<typename _Yp>
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_Assignable<auto_ptr<_Yp>>
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operator=(auto_ptr<_Yp>&& __r)
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{
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this->__shared_ptr<_Tp>::operator=(std::move(__r));
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return *this;
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}
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#pragma GCC diagnostic pop
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#endif
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shared_ptr&
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operator=(shared_ptr&& __r) noexcept
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{
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this->__shared_ptr<_Tp>::operator=(std::move(__r));
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return *this;
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}
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template<class _Yp>
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_Assignable<shared_ptr<_Yp>>
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operator=(shared_ptr<_Yp>&& __r) noexcept
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{
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this->__shared_ptr<_Tp>::operator=(std::move(__r));
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return *this;
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}
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template<typename _Yp, typename _Del>
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_Assignable<unique_ptr<_Yp, _Del>>
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operator=(unique_ptr<_Yp, _Del>&& __r)
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{
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this->__shared_ptr<_Tp>::operator=(std::move(__r));
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return *this;
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}
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private:
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// This constructor is non-standard, it is used by allocate_shared.
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template<typename _Alloc, typename... _Args>
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shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
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: __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...)
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{ }
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template<typename _Yp, typename _Alloc, typename... _Args>
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friend shared_ptr<_Yp>
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allocate_shared(const _Alloc& __a, _Args&&... __args);
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|
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// This constructor is non-standard, it is used by weak_ptr::lock().
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shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t) noexcept
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: __shared_ptr<_Tp>(__r, std::nothrow) { }
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friend class weak_ptr<_Tp>;
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};
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#if __cpp_deduction_guides >= 201606
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template<typename _Tp>
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shared_ptr(weak_ptr<_Tp>) -> shared_ptr<_Tp>;
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template<typename _Tp, typename _Del>
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shared_ptr(unique_ptr<_Tp, _Del>) -> shared_ptr<_Tp>;
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#endif
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|
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// 20.7.2.2.7 shared_ptr comparisons
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|
/// @relates shared_ptr @{
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/// Equality operator for shared_ptr objects, compares the stored pointers
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|
template<typename _Tp, typename _Up>
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|
_GLIBCXX_NODISCARD inline bool
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operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
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{ return __a.get() == __b.get(); }
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/// shared_ptr comparison with nullptr
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template<typename _Tp>
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_GLIBCXX_NODISCARD inline bool
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operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
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{ return !__a; }
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#ifdef __cpp_lib_three_way_comparison
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template<typename _Tp, typename _Up>
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inline strong_ordering
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operator<=>(const shared_ptr<_Tp>& __a,
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const shared_ptr<_Up>& __b) noexcept
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{ return compare_three_way()(__a.get(), __b.get()); }
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template<typename _Tp>
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inline strong_ordering
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operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
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{
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using pointer = typename shared_ptr<_Tp>::element_type*;
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return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
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}
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#else
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/// shared_ptr comparison with nullptr
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template<typename _Tp>
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_GLIBCXX_NODISCARD inline bool
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operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
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{ return !__a; }
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|
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/// Inequality operator for shared_ptr objects, compares the stored pointers
|
|
template<typename _Tp, typename _Up>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
|
|
{ return __a.get() != __b.get(); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
|
|
{ return (bool)__a; }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
|
|
{ return (bool)__a; }
|
|
|
|
/// Relational operator for shared_ptr objects, compares the stored pointers
|
|
template<typename _Tp, typename _Up>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
|
|
{
|
|
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
|
|
using _Up_elt = typename shared_ptr<_Up>::element_type;
|
|
using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
|
|
return less<_Vp>()(__a.get(), __b.get());
|
|
}
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
|
|
{
|
|
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
|
|
return less<_Tp_elt*>()(__a.get(), nullptr);
|
|
}
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
|
|
{
|
|
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
|
|
return less<_Tp_elt*>()(nullptr, __a.get());
|
|
}
|
|
|
|
/// Relational operator for shared_ptr objects, compares the stored pointers
|
|
template<typename _Tp, typename _Up>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
|
|
{ return !(__b < __a); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
|
|
{ return !(nullptr < __a); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
|
|
{ return !(__a < nullptr); }
|
|
|
|
/// Relational operator for shared_ptr objects, compares the stored pointers
|
|
template<typename _Tp, typename _Up>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
|
|
{ return (__b < __a); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
|
|
{ return nullptr < __a; }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
|
|
{ return __a < nullptr; }
|
|
|
|
/// Relational operator for shared_ptr objects, compares the stored pointers
|
|
template<typename _Tp, typename _Up>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
|
|
{ return !(__a < __b); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
|
|
{ return !(__a < nullptr); }
|
|
|
|
/// shared_ptr comparison with nullptr
|
|
template<typename _Tp>
|
|
_GLIBCXX_NODISCARD inline bool
|
|
operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
|
|
{ return !(nullptr < __a); }
|
|
#endif
|
|
|
|
// 20.7.2.2.8 shared_ptr specialized algorithms.
|
|
|
|
/// Swap overload for shared_ptr
|
|
template<typename _Tp>
|
|
inline void
|
|
swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
|
|
{ __a.swap(__b); }
|
|
|
|
// 20.7.2.2.9 shared_ptr casts.
|
|
|
|
/// Convert type of `shared_ptr`, via `static_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
static_pointer_cast(const shared_ptr<_Up>& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
|
|
/// Convert type of `shared_ptr`, via `const_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
const_pointer_cast(const shared_ptr<_Up>& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
|
|
/// Convert type of `shared_ptr`, via `dynamic_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
|
|
return _Sp(__r, __p);
|
|
return _Sp();
|
|
}
|
|
|
|
#if __cplusplus >= 201703L
|
|
/// Convert type of `shared_ptr`, via `reinterpret_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
|
|
#if __cplusplus > 201703L
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2996. Missing rvalue overloads for shared_ptr operations
|
|
|
|
/// Convert type of `shared_ptr` rvalue, via `static_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
static_pointer_cast(shared_ptr<_Up>&& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(std::move(__r),
|
|
static_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
|
|
/// Convert type of `shared_ptr` rvalue, via `const_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
const_pointer_cast(shared_ptr<_Up>&& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(std::move(__r),
|
|
const_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
|
|
/// Convert type of `shared_ptr` rvalue, via `dynamic_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
|
|
return _Sp(std::move(__r), __p);
|
|
return _Sp();
|
|
}
|
|
|
|
/// Convert type of `shared_ptr` rvalue, via `reinterpret_cast`
|
|
template<typename _Tp, typename _Up>
|
|
inline shared_ptr<_Tp>
|
|
reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept
|
|
{
|
|
using _Sp = shared_ptr<_Tp>;
|
|
return _Sp(std::move(__r),
|
|
reinterpret_cast<typename _Sp::element_type*>(__r.get()));
|
|
}
|
|
#endif // C++20
|
|
#endif // C++17
|
|
|
|
/// @}
|
|
|
|
/**
|
|
* @brief A non-owning observer for a pointer owned by a shared_ptr
|
|
*
|
|
* A weak_ptr provides a safe alternative to a raw pointer when you want
|
|
* a non-owning reference to an object that is managed by a shared_ptr.
|
|
*
|
|
* Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr
|
|
* that shares ownership with every other shared_ptr that already owns
|
|
* the pointer. In other words you can upgrade from a non-owning "weak"
|
|
* reference to an owning shared_ptr, without having access to any of
|
|
* the existing shared_ptr objects.
|
|
*
|
|
* Also unlike a raw pointer, a weak_ptr does not become "dangling" after
|
|
* the object it points to has been destroyed. Instead, a weak_ptr
|
|
* becomes _expired_ and can no longer be converted to a shared_ptr that
|
|
* owns the freed pointer, so you cannot accidentally access the pointed-to
|
|
* object after it has been destroyed.
|
|
*/
|
|
template<typename _Tp>
|
|
class weak_ptr : public __weak_ptr<_Tp>
|
|
{
|
|
template<typename _Arg>
|
|
using _Constructible = typename enable_if<
|
|
is_constructible<__weak_ptr<_Tp>, _Arg>::value
|
|
>::type;
|
|
|
|
template<typename _Arg>
|
|
using _Assignable = typename enable_if<
|
|
is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr&
|
|
>::type;
|
|
|
|
public:
|
|
constexpr weak_ptr() noexcept = default;
|
|
|
|
template<typename _Yp,
|
|
typename = _Constructible<const shared_ptr<_Yp>&>>
|
|
weak_ptr(const shared_ptr<_Yp>& __r) noexcept
|
|
: __weak_ptr<_Tp>(__r) { }
|
|
|
|
weak_ptr(const weak_ptr&) noexcept = default;
|
|
|
|
template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
|
|
weak_ptr(const weak_ptr<_Yp>& __r) noexcept
|
|
: __weak_ptr<_Tp>(__r) { }
|
|
|
|
weak_ptr(weak_ptr&&) noexcept = default;
|
|
|
|
template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>>
|
|
weak_ptr(weak_ptr<_Yp>&& __r) noexcept
|
|
: __weak_ptr<_Tp>(std::move(__r)) { }
|
|
|
|
weak_ptr&
|
|
operator=(const weak_ptr& __r) noexcept = default;
|
|
|
|
template<typename _Yp>
|
|
_Assignable<const weak_ptr<_Yp>&>
|
|
operator=(const weak_ptr<_Yp>& __r) noexcept
|
|
{
|
|
this->__weak_ptr<_Tp>::operator=(__r);
|
|
return *this;
|
|
}
|
|
|
|
template<typename _Yp>
|
|
_Assignable<const shared_ptr<_Yp>&>
|
|
operator=(const shared_ptr<_Yp>& __r) noexcept
|
|
{
|
|
this->__weak_ptr<_Tp>::operator=(__r);
|
|
return *this;
|
|
}
|
|
|
|
weak_ptr&
|
|
operator=(weak_ptr&& __r) noexcept = default;
|
|
|
|
template<typename _Yp>
|
|
_Assignable<weak_ptr<_Yp>>
|
|
operator=(weak_ptr<_Yp>&& __r) noexcept
|
|
{
|
|
this->__weak_ptr<_Tp>::operator=(std::move(__r));
|
|
return *this;
|
|
}
|
|
|
|
shared_ptr<_Tp>
|
|
lock() const noexcept
|
|
{ return shared_ptr<_Tp>(*this, std::nothrow); }
|
|
};
|
|
|
|
#if __cpp_deduction_guides >= 201606
|
|
template<typename _Tp>
|
|
weak_ptr(shared_ptr<_Tp>) -> weak_ptr<_Tp>;
|
|
#endif
|
|
|
|
// 20.7.2.3.6 weak_ptr specialized algorithms.
|
|
/// Swap overload for weak_ptr
|
|
/// @relates weak_ptr
|
|
template<typename _Tp>
|
|
inline void
|
|
swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
|
|
{ __a.swap(__b); }
|
|
|
|
|
|
/// Primary template owner_less
|
|
template<typename _Tp = void>
|
|
struct owner_less;
|
|
|
|
/// Void specialization of owner_less compares either shared_ptr or weak_ptr
|
|
template<>
|
|
struct owner_less<void> : _Sp_owner_less<void, void>
|
|
{ };
|
|
|
|
/// Partial specialization of owner_less for shared_ptr.
|
|
template<typename _Tp>
|
|
struct owner_less<shared_ptr<_Tp>>
|
|
: public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
|
|
{ };
|
|
|
|
/// Partial specialization of owner_less for weak_ptr.
|
|
template<typename _Tp>
|
|
struct owner_less<weak_ptr<_Tp>>
|
|
: public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
|
|
{ };
|
|
|
|
/**
|
|
* @brief Base class allowing use of member function shared_from_this.
|
|
*/
|
|
template<typename _Tp>
|
|
class enable_shared_from_this
|
|
{
|
|
protected:
|
|
constexpr enable_shared_from_this() noexcept { }
|
|
|
|
enable_shared_from_this(const enable_shared_from_this&) noexcept { }
|
|
|
|
enable_shared_from_this&
|
|
operator=(const enable_shared_from_this&) noexcept
|
|
{ return *this; }
|
|
|
|
~enable_shared_from_this() { }
|
|
|
|
public:
|
|
shared_ptr<_Tp>
|
|
shared_from_this()
|
|
{ return shared_ptr<_Tp>(this->_M_weak_this); }
|
|
|
|
shared_ptr<const _Tp>
|
|
shared_from_this() const
|
|
{ return shared_ptr<const _Tp>(this->_M_weak_this); }
|
|
|
|
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
|
|
#define __cpp_lib_enable_shared_from_this 201603
|
|
weak_ptr<_Tp>
|
|
weak_from_this() noexcept
|
|
{ return this->_M_weak_this; }
|
|
|
|
weak_ptr<const _Tp>
|
|
weak_from_this() const noexcept
|
|
{ return this->_M_weak_this; }
|
|
#endif
|
|
|
|
private:
|
|
template<typename _Tp1>
|
|
void
|
|
_M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
|
|
{ _M_weak_this._M_assign(__p, __n); }
|
|
|
|
// Found by ADL when this is an associated class.
|
|
friend const enable_shared_from_this*
|
|
__enable_shared_from_this_base(const __shared_count<>&,
|
|
const enable_shared_from_this* __p)
|
|
{ return __p; }
|
|
|
|
template<typename, _Lock_policy>
|
|
friend class __shared_ptr;
|
|
|
|
mutable weak_ptr<_Tp> _M_weak_this;
|
|
};
|
|
|
|
/// @relates shared_ptr @{
|
|
|
|
/**
|
|
* @brief Create an object that is owned by a shared_ptr.
|
|
* @param __a An allocator.
|
|
* @param __args Arguments for the @a _Tp object's constructor.
|
|
* @return A shared_ptr that owns the newly created object.
|
|
* @throw An exception thrown from @a _Alloc::allocate or from the
|
|
* constructor of @a _Tp.
|
|
*
|
|
* A copy of @a __a will be used to allocate memory for the shared_ptr
|
|
* and the new object.
|
|
*/
|
|
template<typename _Tp, typename _Alloc, typename... _Args>
|
|
inline shared_ptr<_Tp>
|
|
allocate_shared(const _Alloc& __a, _Args&&... __args)
|
|
{
|
|
static_assert(!is_array<_Tp>::value, "make_shared<T[]> not supported");
|
|
|
|
return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a},
|
|
std::forward<_Args>(__args)...);
|
|
}
|
|
|
|
/**
|
|
* @brief Create an object that is owned by a shared_ptr.
|
|
* @param __args Arguments for the @a _Tp object's constructor.
|
|
* @return A shared_ptr that owns the newly created object.
|
|
* @throw std::bad_alloc, or an exception thrown from the
|
|
* constructor of @a _Tp.
|
|
*/
|
|
template<typename _Tp, typename... _Args>
|
|
inline shared_ptr<_Tp>
|
|
make_shared(_Args&&... __args)
|
|
{
|
|
typedef typename std::remove_cv<_Tp>::type _Tp_nc;
|
|
return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
|
|
std::forward<_Args>(__args)...);
|
|
}
|
|
|
|
/// std::hash specialization for shared_ptr.
|
|
template<typename _Tp>
|
|
struct hash<shared_ptr<_Tp>>
|
|
: public __hash_base<size_t, shared_ptr<_Tp>>
|
|
{
|
|
size_t
|
|
operator()(const shared_ptr<_Tp>& __s) const noexcept
|
|
{
|
|
return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get());
|
|
}
|
|
};
|
|
|
|
/// @} relates shared_ptr
|
|
/// @} group pointer_abstractions
|
|
|
|
#if __cplusplus >= 201703L
|
|
namespace __detail::__variant
|
|
{
|
|
template<typename> struct _Never_valueless_alt; // see <variant>
|
|
|
|
// Provide the strong exception-safety guarantee when emplacing a
|
|
// shared_ptr into a variant.
|
|
template<typename _Tp>
|
|
struct _Never_valueless_alt<std::shared_ptr<_Tp>>
|
|
: std::true_type
|
|
{ };
|
|
|
|
// Provide the strong exception-safety guarantee when emplacing a
|
|
// weak_ptr into a variant.
|
|
template<typename _Tp>
|
|
struct _Never_valueless_alt<std::weak_ptr<_Tp>>
|
|
: std::true_type
|
|
{ };
|
|
} // namespace __detail::__variant
|
|
#endif // C++17
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif // _SHARED_PTR_H
|