boost/bimap/support/data_type_by.hpp
// Boost.Bimap
//
// Copyright (c) 2006-2007 Matias Capeletto
//
// 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)
/// \file support/data_type_by.hpp
/// \brief Metafunction to access the data types of a bimap
#ifndef BOOST_BIMAP_SUPPORT_DATA_TYPE_BY_HPP
#define BOOST_BIMAP_SUPPORT_DATA_TYPE_BY_HPP
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/config.hpp>
#include <boost/bimap/relation/detail/metadata_access_builder.hpp>
/** \struct boost::bimaps::support::data_type_by
\brief Metafunction to obtain the data type of one of the sides in a bimap
The tag parameter can be either a user defined tag or \c member_at::{side}.
This is the actual data type stored in the bimap.
\code
template< class Tag, class Bimap >
struct data_type_by
{
typedef typename Bimap::{side}_data_type type;
};
\endcode
The following holds:
\code
BOOST_STATIC_ASSERT
(
is_same< data_type_by< member_at::left, bimap<A,B> >::type, A >::value
)
\endcode
See also member_at.
\ingroup bimap_group
**/
namespace boost {
namespace bimaps {
namespace support {
// Implementation of data type of metafunction
BOOST_BIMAP_SYMMETRIC_METADATA_ACCESS_BUILDER
(
data_type_by,
left_data_type,
right_data_type
)
} // namespace support
} // namespace bimaps
} // namespace boost
#endif // BOOST_BIMAP_SUPPORT_DATA_TYPE_BY_HPP