#ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED | |
#define BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED | |
// | |
// enable_shared_from_this2.hpp | |
// | |
// Copyright 2002, 2009 Peter Dimov | |
// Copyright 2008 Frank Mori Hess | |
// | |
// Distributed under the Boost Software License, Version 1.0. | |
// See accompanying file LICENSE_1_0.txt or copy at | |
// http://www.boost.org/LICENSE_1_0.txt | |
// | |
#include <boost/config.hpp> | |
#include <boost/shared_ptr.hpp> | |
#include <boost/assert.hpp> | |
#include <boost/detail/workaround.hpp> | |
namespace boost | |
{ | |
namespace detail | |
{ | |
class esft2_deleter_wrapper | |
{ | |
private: | |
shared_ptr<void> deleter_; | |
public: | |
esft2_deleter_wrapper() | |
{ | |
} | |
template< class T > void set_deleter( shared_ptr<T> const & deleter ) | |
{ | |
deleter_ = deleter; | |
} | |
template< class T> void operator()( T* ) | |
{ | |
BOOST_ASSERT( deleter_.use_count() <= 1 ); | |
deleter_.reset(); | |
} | |
}; | |
} // namespace detail | |
template< class T > class enable_shared_from_this2 | |
{ | |
protected: | |
enable_shared_from_this2() | |
{ | |
} | |
enable_shared_from_this2( enable_shared_from_this2 const & ) | |
{ | |
} | |
enable_shared_from_this2 & operator=( enable_shared_from_this2 const & ) | |
{ | |
return *this; | |
} | |
~enable_shared_from_this2() | |
{ | |
BOOST_ASSERT( shared_this_.use_count() <= 1 ); // make sure no dangling shared_ptr objects exist | |
} | |
private: | |
mutable weak_ptr<T> weak_this_; | |
mutable shared_ptr<T> shared_this_; | |
public: | |
shared_ptr<T> shared_from_this() | |
{ | |
init_weak_once(); | |
return shared_ptr<T>( weak_this_ ); | |
} | |
shared_ptr<T const> shared_from_this() const | |
{ | |
init_weak_once(); | |
return shared_ptr<T>( weak_this_ ); | |
} | |
private: | |
void init_weak_once() const | |
{ | |
if( weak_this_._empty() ) | |
{ | |
shared_this_.reset( static_cast< T* >( 0 ), detail::esft2_deleter_wrapper() ); | |
weak_this_ = shared_this_; | |
} | |
} | |
public: // actually private, but avoids compiler template friendship issues | |
// Note: invoked automatically by shared_ptr; do not call | |
template<class X, class Y> void _internal_accept_owner( shared_ptr<X> * ppx, Y * py ) const | |
{ | |
BOOST_ASSERT( ppx != 0 ); | |
if( weak_this_.use_count() == 0 ) | |
{ | |
weak_this_ = shared_ptr<T>( *ppx, py ); | |
} | |
else if( shared_this_.use_count() != 0 ) | |
{ | |
BOOST_ASSERT( ppx->unique() ); // no weak_ptrs should exist either, but there's no way to check that | |
detail::esft2_deleter_wrapper * pd = boost::get_deleter<detail::esft2_deleter_wrapper>( shared_this_ ); | |
BOOST_ASSERT( pd != 0 ); | |
pd->set_deleter( *ppx ); | |
ppx->reset( shared_this_, ppx->get() ); | |
shared_this_.reset(); | |
} | |
} | |
}; | |
} // namespace boost | |
#endif // #ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED |