133 lines
3.0 KiB
C++
133 lines
3.0 KiB
C++
#ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED
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#define BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED
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//
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// enable_shared_from_this2.hpp
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//
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// Copyright 2002, 2009 Peter Dimov
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// Copyright 2008 Frank Mori Hess
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//
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// Distributed under the Boost Software License, Version 1.0.
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// See 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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//
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#include <boost/config.hpp>
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#include <boost/shared_ptr.hpp>
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#include <boost/assert.hpp>
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#include <boost/detail/workaround.hpp>
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namespace boost
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{
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namespace detail
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{
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class esft2_deleter_wrapper
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{
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private:
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shared_ptr<void> deleter_;
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public:
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esft2_deleter_wrapper()
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{
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}
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template< class T > void set_deleter( shared_ptr<T> const & deleter )
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{
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deleter_ = deleter;
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}
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template< class T> void operator()( T* )
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{
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BOOST_ASSERT( deleter_.use_count() <= 1 );
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deleter_.reset();
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}
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};
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} // namespace detail
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template< class T > class enable_shared_from_this2
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{
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protected:
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enable_shared_from_this2()
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{
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}
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enable_shared_from_this2( enable_shared_from_this2 const & )
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{
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}
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enable_shared_from_this2 & operator=( enable_shared_from_this2 const & )
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{
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return *this;
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}
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~enable_shared_from_this2()
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{
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BOOST_ASSERT( shared_this_.use_count() <= 1 ); // make sure no dangling shared_ptr objects exist
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}
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private:
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mutable weak_ptr<T> weak_this_;
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mutable shared_ptr<T> shared_this_;
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public:
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shared_ptr<T> shared_from_this()
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{
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init_weak_once();
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return shared_ptr<T>( weak_this_ );
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}
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shared_ptr<T const> shared_from_this() const
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{
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init_weak_once();
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return shared_ptr<T>( weak_this_ );
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}
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private:
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void init_weak_once() const
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{
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if( weak_this_._empty() )
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{
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shared_this_.reset( static_cast< T* >( 0 ), detail::esft2_deleter_wrapper() );
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weak_this_ = shared_this_;
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}
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}
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public: // actually private, but avoids compiler template friendship issues
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// Note: invoked automatically by shared_ptr; do not call
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template<class X, class Y> void _internal_accept_owner( shared_ptr<X> * ppx, Y * py ) const
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{
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BOOST_ASSERT( ppx != 0 );
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if( weak_this_.use_count() == 0 )
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{
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weak_this_ = shared_ptr<T>( *ppx, py );
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}
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else if( shared_this_.use_count() != 0 )
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{
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BOOST_ASSERT( ppx->unique() ); // no weak_ptrs should exist either, but there's no way to check that
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detail::esft2_deleter_wrapper * pd = boost::get_deleter<detail::esft2_deleter_wrapper>( shared_this_ );
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BOOST_ASSERT( pd != 0 );
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pd->set_deleter( *ppx );
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ppx->reset( shared_this_, ppx->get() );
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shared_this_.reset();
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}
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}
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};
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} // namespace boost
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#endif // #ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED
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