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// 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

/// \file relation/member_at.hpp
/// \brief Defines the tags for the member_at::side idiom


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

#include <boost/config.hpp>

namespace boost {
namespace bimaps {
namespace relation {

/// \brief member_at::side idiom to access relation values and types using metaprogramming. 

This tags are used to specify which member you want to acces when using a metafunction over
a symmetrical type. The idea is to be able to write code like:

result_of::get<member_at::left,relation>::type data = get<member_at::left>(rel);

The relation class supports this idiom even when the elements are tagged. This is useful
because a user can decide to start tagging in any moment of the development.

See also member_with_tag, is_tag_of_member_at_left, is_tag_of_member_at_right, get
value_type_of, pair_by, pair_type_by.

\ingroup relation_group
namespace member_at {

    /// \brief Member at left tag
    See also member_at, rigth.

    struct left  {};

    /// \brief Member at right tag
    See also member_at, left.

    struct right {};

    /// \brief Member info tag
    See also member_at, left, right.

    struct info  {};


} // namespace relation
} // namespace bimaps
} // namespace boost