| #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 |