997 lines
24 KiB
C++
997 lines
24 KiB
C++
// <tr1/memory> -*- C++ -*-
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// Copyright (C) 2005 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 2, 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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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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// boost/checked_delete.hpp
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// Copyright (c) 2002, 2003 Peter Dimov
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// Copyright (c) 2003 Daniel Frey
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// Copyright (c) 2003 Howard Hinnant
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// boost/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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// (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
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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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#ifndef _TR1_MEMORY
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#define _TR1_MEMORY 1
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#include "../memory"
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#include <functional> // std::less
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#include <exception> // std::exception
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#include <new> // std::bad_alloc
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#include <typeinfo> // std::type_info in get_deleter
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#include <cstddef> // std::size_t
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#include <algorithm> // for std::swap
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#include <iosfwd> // for std::basic_ostream
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#include <cstdlib> // for std::abort
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#include <bits/gthr.h>
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#include <bits/atomicity.h>
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#include <bits/functexcept.h>
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#include <debug/debug.h>
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// namespace std::tr1
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namespace std
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{
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namespace tr1
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{
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class bad_weak_ptr : public std::exception
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{
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public:
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virtual char const* what() const throw()
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{
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return "tr1::bad_weak_ptr";
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}
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};
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// Helper for exception objects in <tr1/memory>
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// TODO this should be defined in a different file.
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void
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__throw_bad_weak_ptr()
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{
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#if __EXCEPTIONS
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throw bad_weak_ptr();
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#else
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std::abort();
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#endif
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}
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// verify that types are complete for increased safety
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template <typename _Tp>
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inline void
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checked_delete(_Tp * __x)
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{
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// intentionally complex - simplification causes regressions
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typedef char type_must_be_complete[ sizeof(_Tp)? 1: -1 ];
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(void) sizeof(type_must_be_complete);
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delete __x;
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}
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template <typename _Tp>
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struct checked_deleter
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{
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typedef void result_type;
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typedef _Tp* argument_type;
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void
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operator()(_Tp * x) const
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{ std::tr1::checked_delete(x); }
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};
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class _Sp_counted_base
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{
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public:
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_Sp_counted_base()
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: _M_use_count(1), _M_weak_count(1)
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{ }
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virtual
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~_Sp_counted_base() // nothrow
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{ }
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// dispose() is called when _M_use_count drops to zero, to release
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// the resources managed by *this.
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virtual void
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dispose() = 0; // nothrow
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// destroy() is called when _M_weak_count drops to zero.
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virtual void
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destroy() // nothrow
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{
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delete this;
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}
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virtual void*
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get_deleter(const std::type_info&) = 0;
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void
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add_ref_copy()
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{
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__gnu_cxx::__atomic_add(&_M_use_count, 1);
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}
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void
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add_ref_lock()
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{
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if (_M_use_count <= 0) // TODO not yet MT safe XXX
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{
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__throw_bad_weak_ptr();
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}
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__gnu_cxx::__atomic_add(&_M_use_count, 1);
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}
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void
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release() // nothrow
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{
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if (__gnu_cxx::__exchange_and_add(&_M_use_count, -1) <= 1)
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{
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dispose();
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weak_release();
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}
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}
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void
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weak_add_ref() // nothrow
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{
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__gnu_cxx::__atomic_add(&_M_weak_count, 1);
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}
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void
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weak_release() // nothrow
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{
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if (__gnu_cxx::__exchange_and_add(&_M_weak_count, -1) <= 1)
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{
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destroy();
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}
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}
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long
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use_count() const // nothrow
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{
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return _M_use_count; // XXX is this MT safe?
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}
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private:
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_Sp_counted_base(_Sp_counted_base const&);
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_Sp_counted_base& operator= (_Sp_counted_base const&);
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_Atomic_word _M_use_count; // #shared
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_Atomic_word _M_weak_count; // #weak + (#shared != 0)
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};
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template <typename _Ptr, typename _Deleter>
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class _Sp_counted_base_impl : public _Sp_counted_base
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{
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public:
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/**
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* @brief
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* @pre d(p) must not throw.
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*/
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_Sp_counted_base_impl(_Ptr __p, _Deleter __d)
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: _M_ptr(__p), _M_del(__d)
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{ }
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virtual void
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dispose() // nothrow
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{
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_M_del(_M_ptr);
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}
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virtual void*
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get_deleter(const std::type_info& __ti)
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{
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return __ti == typeid(_Deleter) ? &_M_del : 0;
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}
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private:
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_Sp_counted_base_impl(const _Sp_counted_base_impl&);
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_Sp_counted_base_impl& operator=(const _Sp_counted_base_impl&);
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_Ptr _M_ptr; // copy constructor must not throw
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_Deleter _M_del; // copy constructor must not throw
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};
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class weak_count;
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class shared_count
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{
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private:
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_Sp_counted_base* _M_pi;
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friend class weak_count;
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public:
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shared_count()
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: _M_pi(0) // nothrow
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{ }
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template <typename _Ptr, typename _Deleter>
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shared_count(_Ptr __p, _Deleter __d)
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: _M_pi(0)
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{
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try
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{
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_M_pi = new _Sp_counted_base_impl<_Ptr, _Deleter>(__p, __d);
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}
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catch(...)
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{
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__d(__p); // delete __p
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__throw_exception_again;
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}
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}
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// auto_ptr<_Tp> is special cased to provide the strong guarantee
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template <typename _Tp>
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explicit shared_count(std::auto_ptr<_Tp>& __r)
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: _M_pi(new _Sp_counted_base_impl<_Tp*,checked_deleter<_Tp> >(
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__r.get(), checked_deleter<_Tp>()
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))
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{ __r.release(); }
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// throws bad_weak_ptr when __r.use_count() == 0
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explicit shared_count(const weak_count& __r);
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~shared_count() // nothrow
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{
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if (_M_pi != 0)
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_M_pi->release();
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}
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shared_count(const shared_count& __r)
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: _M_pi(__r._M_pi) // nothrow
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{
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if (_M_pi != 0)
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_M_pi->add_ref_copy();
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}
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shared_count&
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operator=(const shared_count& __r) // nothrow
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{
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_Sp_counted_base* __tmp = __r._M_pi;
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if(__tmp != _M_pi)
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{
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if(__tmp != 0)
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__tmp->add_ref_copy();
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if(_M_pi != 0)
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_M_pi->release();
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_M_pi = __tmp;
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}
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return *this;
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}
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void swap(shared_count& __r) // nothrow
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{
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_Sp_counted_base* __tmp = __r._M_pi;
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__r._M_pi = _M_pi;
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_M_pi = __tmp;
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}
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long
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use_count() const // nothrow
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{ return _M_pi != 0 ? _M_pi->use_count() : 0; }
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bool
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unique() const // nothrow
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{ return this->use_count() == 1; }
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friend inline bool
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operator==(const shared_count& __a, const shared_count& __b)
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{ return __a._M_pi == __b._M_pi; }
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friend inline bool
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operator<(const shared_count& __a, const shared_count& __b)
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{ return std::less<_Sp_counted_base*>()(__a._M_pi, __b._M_pi); }
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void*
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get_deleter(const std::type_info& __ti) const
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{ return _M_pi ? _M_pi->get_deleter(__ti) : 0; }
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};
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class weak_count
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{
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private:
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_Sp_counted_base * _M_pi;
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friend class shared_count;
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public:
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weak_count()
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: _M_pi(0) // nothrow
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{ }
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weak_count(const shared_count& __r)
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: _M_pi(__r._M_pi) // nothrow
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{
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if (_M_pi != 0)
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_M_pi->weak_add_ref();
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}
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weak_count(const weak_count& __r)
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: _M_pi(__r._M_pi) // nothrow
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{
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if (_M_pi != 0)
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_M_pi->weak_add_ref();
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}
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~weak_count() // nothrow
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{
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if (_M_pi != 0)
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_M_pi->weak_release();
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}
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weak_count&
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operator=(const shared_count& __r) // nothrow
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{
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_Sp_counted_base* __tmp = __r._M_pi;
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if (__tmp != 0)
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__tmp->weak_add_ref();
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if (_M_pi != 0)
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_M_pi->weak_release();
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_M_pi = __tmp;
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return *this;
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}
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weak_count&
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operator=(const weak_count& __r) // nothrow
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{
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_Sp_counted_base * __tmp = __r._M_pi;
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if (__tmp != 0)
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__tmp->weak_add_ref();
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if (_M_pi != 0)
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_M_pi->weak_release();
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_M_pi = __tmp;
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return *this;
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}
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void
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swap(weak_count& __r) // nothrow
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{
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_Sp_counted_base * __tmp = __r._M_pi;
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__r._M_pi = _M_pi;
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_M_pi = __tmp;
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}
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long
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use_count() const // nothrow
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{ return _M_pi != 0 ? _M_pi->use_count() : 0; }
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friend inline bool
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operator==(const weak_count& __a, const weak_count& __b)
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{ return __a._M_pi == __b._M_pi; }
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friend inline bool
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operator<(const weak_count& __a, const weak_count& __b)
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{ return std::less<_Sp_counted_base*>()(__a._M_pi, __b._M_pi); }
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};
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inline
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shared_count::shared_count(const weak_count& __r)
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: _M_pi(__r._M_pi)
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{
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if (_M_pi != 0)
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{
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_M_pi->add_ref_lock();
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}
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else
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{
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__throw_bad_weak_ptr();
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}
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}
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// fwd decls
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template <typename _Tp> class weak_ptr;
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template <typename _Tp> class enable_shared_from_this;
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struct __static_cast_tag {};
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struct __const_cast_tag {};
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struct __dynamic_cast_tag {};
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struct __polymorphic_cast_tag {};
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template<class _Tp> struct shared_ptr_traits
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{
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typedef _Tp & reference;
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};
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template<> struct shared_ptr_traits<void>
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{
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typedef void reference;
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};
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template<> struct shared_ptr_traits<void const>
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{
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typedef void reference;
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};
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template<> struct shared_ptr_traits<void volatile>
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{
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typedef void reference;
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};
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template<> struct shared_ptr_traits<void const volatile>
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{
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typedef void reference;
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};
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// enable_shared_from_this support
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// friend of enable_shared_from_this
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template <typename _Tp1, typename _Tp2>
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void
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__enable_shared_from_this( const shared_count& __pn,
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const enable_shared_from_this<_Tp1>* __pe,
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const _Tp2* __px );
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inline void
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__enable_shared_from_this(const shared_count&, ...)
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{ }
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/**
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* @class shared_ptr <tr1/memory>
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*
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* A smart pointer with reference-counted copy semantics.
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* The object pointed to is deleted when the last shared_ptr pointing to it
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* is destroyed or reset.
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*/
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template <typename _Tp>
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class shared_ptr
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{
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typedef typename shared_ptr_traits<_Tp>::reference _Reference;
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public:
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typedef _Tp element_type;
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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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shared_ptr() : _M_ptr(0), _M_refcount() // never throws
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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 _Tp1>
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explicit shared_ptr(_Tp1* __p)
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: _M_ptr(__p), _M_refcount(__p, checked_deleter<_Tp1>())
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{
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__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
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// __glibcxx_function_requires(_CompleteConcept<_Tp1*>)
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__enable_shared_from_this( _M_refcount, __p, __p );
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}
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//
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// Requirements: D's copy constructor and destructor must 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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/** @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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template <typename _Tp1, typename _Deleter>
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shared_ptr(_Tp1* __p, _Deleter __d)
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: _M_ptr(__p), _M_refcount(__p, __d)
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{
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__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
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// TODO requires D is CopyConstructible and d(p) well-formed
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__enable_shared_from_this( _M_refcount, __p, __p );
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}
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// generated copy constructor, assignment, destructor are fine.
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/** @brief If @a r is empty, constructs an empty %shared_ptr; otherwise
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* construct a %shared_ptr that shares ownership 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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* @throw std::bad_alloc, in which case
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*/
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template <typename _Tp1>
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shared_ptr(const shared_ptr<_Tp1>& __r)
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: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
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{
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__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
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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 _Tp1>
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explicit shared_ptr(const weak_ptr<_Tp1>& __r)
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: _M_refcount(__r._M_refcount) // may throw
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{
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__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
|
|
// it is now safe to copy r__._M_ptr, as _M_refcount(__r._M_refcount)
|
|
// did not throw
|
|
_M_ptr = __r._M_ptr;
|
|
}
|
|
|
|
/**
|
|
* @post use_count()==1 and r.get()==0
|
|
*/
|
|
template <typename _Tp1>
|
|
explicit shared_ptr(std::auto_ptr<_Tp1>& __r)
|
|
: _M_ptr(__r.get()), _M_refcount()
|
|
{
|
|
// TODO requires r.release() convertible to _Tp*, Tp1 is complete,
|
|
// delete r.release() well-formed
|
|
_Tp1 * __tmp = __r.get();
|
|
_M_refcount = shared_count(__r);
|
|
|
|
__enable_shared_from_this( _M_refcount, __tmp, __tmp );
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
shared_ptr(const shared_ptr<_Tp1>& __r, __static_cast_tag)
|
|
: _M_ptr(static_cast<element_type*>(__r._M_ptr))
|
|
, _M_refcount(__r._M_refcount)
|
|
{ }
|
|
|
|
template <typename _Tp1>
|
|
shared_ptr(const shared_ptr<_Tp1>& __r, __const_cast_tag)
|
|
: _M_ptr(const_cast<element_type*>(__r._M_ptr))
|
|
, _M_refcount(__r._M_refcount)
|
|
{ }
|
|
|
|
template <typename _Tp1>
|
|
shared_ptr(const shared_ptr<_Tp1>& __r, __dynamic_cast_tag)
|
|
: _M_ptr(dynamic_cast<element_type*>(__r._M_ptr))
|
|
, _M_refcount(__r._M_refcount)
|
|
{
|
|
if (_M_ptr == 0) // need to allocate new counter -- the cast failed
|
|
{
|
|
_M_refcount = shared_count();
|
|
}
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
shared_ptr&
|
|
operator=(const shared_ptr<_Tp1>& __r) // never throws
|
|
{
|
|
_M_ptr = __r._M_ptr;
|
|
_M_refcount = __r._M_refcount; // shared_count::op= doesn't throw
|
|
return *this;
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
shared_ptr&
|
|
operator=(std::auto_ptr<_Tp1>& __r)
|
|
{
|
|
shared_ptr(__r).swap(*this);
|
|
return *this;
|
|
}
|
|
|
|
void
|
|
reset() // never throws
|
|
{ shared_ptr().swap(*this); }
|
|
|
|
template <typename _Tp1>
|
|
void
|
|
reset(_Tp1* __p) // _Tp1 must be complete
|
|
{
|
|
_GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); // catch self-reset errors
|
|
shared_ptr(__p).swap(*this);
|
|
}
|
|
|
|
template <typename _Tp1, typename _Deleter>
|
|
void
|
|
reset(_Tp1 * __p, _Deleter __d)
|
|
{ shared_ptr(__p, __d).swap(*this); }
|
|
|
|
// error to instantiate if _Tp is [cv-qual] void
|
|
_Reference
|
|
operator*() const // never throws
|
|
{
|
|
_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
|
|
return *_M_ptr;
|
|
}
|
|
|
|
_Tp*
|
|
operator->() const // never throws
|
|
{
|
|
_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
|
|
return _M_ptr;
|
|
}
|
|
|
|
_Tp*
|
|
get() const // never throws
|
|
{ return _M_ptr; }
|
|
|
|
// implicit conversion to "bool"
|
|
private:
|
|
typedef _Tp* shared_ptr::*__unspecified_bool_type;
|
|
|
|
public:
|
|
operator __unspecified_bool_type() const // never throws
|
|
{ return _M_ptr == 0 ? 0 : &shared_ptr::_M_ptr; }
|
|
|
|
bool
|
|
unique() const // never throws
|
|
{ return _M_refcount.unique(); }
|
|
|
|
long
|
|
use_count() const // never throws
|
|
{ return _M_refcount.use_count(); }
|
|
|
|
void
|
|
swap(shared_ptr<_Tp>& __other) // never throws
|
|
{
|
|
std::swap(_M_ptr, __other._M_ptr);
|
|
_M_refcount.swap(__other._M_refcount);
|
|
}
|
|
|
|
private:
|
|
template <typename _Tp1>
|
|
bool
|
|
_M_less(const shared_ptr<_Tp1>& __rhs) const
|
|
{ return _M_refcount < __rhs._M_refcount; }
|
|
|
|
void*
|
|
_M_get_deleter(const std::type_info& __ti) const
|
|
{ return _M_refcount.get_deleter(__ti); }
|
|
|
|
template <typename _Tp1> friend class shared_ptr;
|
|
template <typename _Tp1> friend class weak_ptr;
|
|
|
|
// friends injected into enclosing namespace and found by ADL:
|
|
|
|
// get_deleter (experimental)
|
|
template <typename _Del>
|
|
friend inline _Del*
|
|
get_deleter(const shared_ptr& __p)
|
|
{ return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); }
|
|
|
|
template <typename _Tp1>
|
|
friend inline bool
|
|
operator==(const shared_ptr& __a, const shared_ptr<_Tp1>& __b)
|
|
{ return __a.get() == __b.get(); }
|
|
|
|
template <typename _Tp1>
|
|
friend inline bool
|
|
operator!=(const shared_ptr& __a, const shared_ptr<_Tp1>& __b)
|
|
{ return __a.get() != __b.get(); }
|
|
|
|
template <typename _Tp1>
|
|
friend inline bool
|
|
operator<(const shared_ptr& __a, const shared_ptr<_Tp1>& __b)
|
|
{ return __a._M_less(__b); }
|
|
|
|
_Tp* _M_ptr; // contained pointer
|
|
shared_count _M_refcount; // reference counter
|
|
}; // shared_ptr
|
|
|
|
// 2.2.3.9 shared_ptr casts
|
|
|
|
/** @warning The seemingly equivalent
|
|
* <code>shared_ptr<T>(static_cast<T*>(r.get()))</code>
|
|
* will eventually result in undefined behaviour,
|
|
* attempting to delete the same object twice.
|
|
*/
|
|
template <typename _Tp, typename _Tp1>
|
|
shared_ptr<_Tp>
|
|
static_pointer_cast(const shared_ptr<_Tp1>& __r)
|
|
{
|
|
return shared_ptr<_Tp>(__r, __static_cast_tag());
|
|
}
|
|
|
|
/** @warning The seemingly equivalent
|
|
* <code>shared_ptr<T>(const_cast<T*>(r.get()))</code>
|
|
* will eventually result in undefined behaviour,
|
|
* attempting to delete the same object twice.
|
|
*/
|
|
template <typename _Tp, typename _Tp1>
|
|
shared_ptr<_Tp>
|
|
const_pointer_cast(const shared_ptr<_Tp1>& __r)
|
|
{
|
|
return shared_ptr<_Tp>(__r, __const_cast_tag());
|
|
}
|
|
|
|
/** @warning The seemingly equivalent
|
|
* <code>shared_ptr<T>(dynamic_cast<T*>(r.get()))</code>
|
|
* will eventually result in undefined behaviour,
|
|
* attempting to delete the same object twice.
|
|
*/
|
|
template <typename _Tp, typename _Tp1>
|
|
shared_ptr<_Tp>
|
|
dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
|
|
{
|
|
return shared_ptr<_Tp>(__r, __dynamic_cast_tag());
|
|
}
|
|
|
|
// operator<<
|
|
template <typename _Ch, typename _Tr, typename _Tp>
|
|
std::basic_ostream<_Ch,_Tr>&
|
|
operator<<(std::basic_ostream<_Ch,_Tr>& __os, const shared_ptr<_Tp>& __p)
|
|
{
|
|
__os << __p.get();
|
|
return __os;
|
|
}
|
|
|
|
|
|
template <typename _Tp>
|
|
class weak_ptr
|
|
{
|
|
public:
|
|
|
|
typedef _Tp element_type;
|
|
|
|
weak_ptr()
|
|
: _M_ptr(0), _M_refcount() // never throws
|
|
{ }
|
|
|
|
// generated copy constructor, assignment, destructor are fine
|
|
|
|
//
|
|
// The "obvious" converting constructor implementation:
|
|
//
|
|
// template<class Y>
|
|
// weak_ptr(weak_ptr<Y> const & r): _M_ptr(r._M_ptr), _M_refcount(r._M_refcount) // never throws
|
|
// {
|
|
// }
|
|
//
|
|
// has a serious problem.
|
|
//
|
|
// r._M_ptr may already have been invalidated. The _M_ptr(r._M_ptr)
|
|
// conversion may require access to *r._M_ptr (virtual inheritance).
|
|
//
|
|
// It is not possible to avoid spurious access violations since
|
|
// in multithreaded programs r._M_ptr may be invalidated at any point.
|
|
//
|
|
|
|
template <typename _Tp1>
|
|
weak_ptr(const weak_ptr<_Tp1>& r)
|
|
: _M_refcount(r._M_refcount) // never throws
|
|
{
|
|
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
|
|
_M_ptr = r.lock().get();
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
weak_ptr(const shared_ptr<_Tp1>& r)
|
|
: _M_ptr(r._M_ptr), _M_refcount(r._M_refcount) // never throws
|
|
{
|
|
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
weak_ptr&
|
|
operator=(const weak_ptr<_Tp1>& r) // never throws
|
|
{
|
|
_M_ptr = r.lock().get();
|
|
_M_refcount = r._M_refcount;
|
|
return *this;
|
|
}
|
|
|
|
template <typename _Tp1>
|
|
weak_ptr&
|
|
operator=(const shared_ptr<_Tp1>& r) // never throws
|
|
{
|
|
_M_ptr = r._M_ptr;
|
|
_M_refcount = r._M_refcount;
|
|
return *this;
|
|
}
|
|
|
|
shared_ptr<_Tp>
|
|
lock() const // never throws
|
|
{
|
|
#ifdef __GTHREADS
|
|
|
|
// optimization: avoid throw overhead
|
|
if (expired())
|
|
{
|
|
return shared_ptr<element_type>();
|
|
}
|
|
|
|
try
|
|
{
|
|
return shared_ptr<element_type>(*this);
|
|
}
|
|
catch (const bad_weak_ptr&)
|
|
{
|
|
// Q: how can we get here?
|
|
// A: another thread may have invalidated r after the use_count test above.
|
|
return shared_ptr<element_type>();
|
|
}
|
|
|
|
#else
|
|
|
|
// optimization: avoid try/catch overhead when single threaded
|
|
return expired() ? shared_ptr<element_type>() : shared_ptr<element_type>(*this);
|
|
|
|
#endif
|
|
} // XXX MT
|
|
|
|
|
|
long
|
|
use_count() const // never throws
|
|
{ return _M_refcount.use_count(); }
|
|
|
|
bool
|
|
expired() const // never throws
|
|
{ return _M_refcount.use_count() == 0; }
|
|
|
|
void
|
|
reset() // never throws
|
|
{ weak_ptr().swap(*this); }
|
|
|
|
void
|
|
swap(weak_ptr& __s) // never throws
|
|
{
|
|
std::swap(_M_ptr, __s._M_ptr);
|
|
_M_refcount.swap(__s._M_refcount);
|
|
}
|
|
|
|
private:
|
|
|
|
template <typename _Tp1>
|
|
bool
|
|
_M_less(const weak_ptr<_Tp1>& __rhs) const
|
|
{ return _M_refcount < __rhs._M_refcount; }
|
|
|
|
// used by __enable_shared_from_this
|
|
void
|
|
_M_assign(_Tp* __ptr, const shared_count& __refcount)
|
|
{
|
|
_M_ptr = __ptr;
|
|
_M_refcount = __refcount;
|
|
}
|
|
|
|
// friend injected into namespace and found by ADL
|
|
|
|
template <typename _Tp1>
|
|
friend inline bool
|
|
operator<(const weak_ptr& __lhs, const weak_ptr<_Tp1>& __rhs)
|
|
{ return __lhs._M_less(__rhs); }
|
|
|
|
template <typename _Tp1> friend class weak_ptr;
|
|
template <typename _Tp1> friend class shared_ptr;
|
|
friend class enable_shared_from_this<_Tp>;
|
|
|
|
_Tp* _M_ptr; // contained pointer
|
|
weak_count _M_refcount; // reference counter
|
|
|
|
}; // weak_ptr
|
|
|
|
|
|
|
|
template <typename _Tp>
|
|
class enable_shared_from_this
|
|
{
|
|
protected:
|
|
|
|
enable_shared_from_this()
|
|
{ }
|
|
|
|
enable_shared_from_this(const enable_shared_from_this&)
|
|
{ }
|
|
|
|
enable_shared_from_this&
|
|
operator=(const enable_shared_from_this&)
|
|
{ return *this; }
|
|
|
|
~enable_shared_from_this()
|
|
{ }
|
|
|
|
public:
|
|
|
|
shared_ptr<_Tp>
|
|
shared_from_this()
|
|
{
|
|
shared_ptr<_Tp> p(this->_M_weak_this);
|
|
return p;
|
|
}
|
|
|
|
shared_ptr<const _Tp>
|
|
shared_from_this() const
|
|
{
|
|
shared_ptr<const _Tp> p(this->_M_weak_this);
|
|
return p;
|
|
}
|
|
|
|
private:
|
|
template <typename _Tp1>
|
|
void
|
|
_M_weak_assign(_Tp1* __p, const shared_count& __n) const
|
|
{ _M_weak_this._M_assign(__p, __n); }
|
|
|
|
template <typename _Tp1>
|
|
friend void
|
|
__enable_shared_from_this( const shared_count& __pn, const enable_shared_from_this* __pe, const _Tp1* __px)
|
|
{
|
|
if(__pe != 0)
|
|
__pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
|
|
}
|
|
|
|
mutable weak_ptr<_Tp> _M_weak_this;
|
|
};
|
|
|
|
} // namespace tr1
|
|
|
|
/**
|
|
* @brief std::swap() specialisation for shared_ptr.
|
|
* @relates shared_ptr.
|
|
*/
|
|
template <typename _Tp>
|
|
inline void
|
|
swap(tr1::shared_ptr<_Tp>& __a, tr1::shared_ptr<_Tp>& __b)
|
|
{
|
|
__a.swap(__b);
|
|
}
|
|
|
|
/**
|
|
* @brief std::swap() specialisation for weak_ptr.
|
|
* @relates weak_ptr.
|
|
*/
|
|
template <typename _Tp>
|
|
void
|
|
swap(tr1::weak_ptr<_Tp>& __a, tr1::weak_ptr<_Tp>& __b)
|
|
{
|
|
__a.swap(__b);
|
|
}
|
|
|
|
} // namespace std
|
|
|
|
#endif
|