/* Copyright 2003-2005 Joaquín M López Muñoz.

 * 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)

 *

 * See http://www.boost.org/libs/multi_index for library home page.

 */

#ifndef BOOST_MULTI_INDEX_DETAIL_HEADER_HOLDER_HPP

#define BOOST_MULTI_INDEX_DETAIL_HEADER_HOLDER_HPP

#if defined(_MSC_VER)&&(_MSC_VER>=1200)

#pragma once

#endif

#include <boost/noncopyable.hpp>

namespace boost{

namespace multi_index{

namespace detail{

/* A utility class used to hold a pointer to the header node.

 * The base from member idiom is used because index classes, which are

 * superclasses of multi_index_container, need this header in construction

 * time. The allocation is made by the allocator of the multi_index_container

 * class --hence, this allocator needs also be stored resorting

 * to the base from member trick.

 */

template<typename NodeType,typename Final>

struct header_holder:private noncopyable

{

  header_holder():member(final().allocate_node()){}

  ~header_holder(){final().deallocate_node(member);}

  NodeType* member;

private:

  Final& final(){return *static_cast<Final*>(this);}

};

} /* namespace multi_index::detail */

} /* namespace multi_index */

} /* namespace boost */

#endif