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diff --git a/boost/bimap/relation/support/data_extractor.hpp b/boost/bimap/relation/support/data_extractor.hpp
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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
+// http://www.boost.org/LICENSE_1_0.txt)
+
+/// \file relation/support/data_extractor.hpp
+/// \brief Data extraction functor.
+
+#ifndef BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
+#define BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER>=1200)
+#pragma once
+#endif
+
+#include <boost/config.hpp>
+
+#include <boost/bimap/relation/detail/metadata_access_builder.hpp>
+#include <functional>
+
+/** \struct boost::bimaps::relation::support::data_extractor
+
+\brief Data extraction functor.
+
+\ingroup relation_group
+                                                                    **/
+
+#ifndef BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES
+
+namespace boost {
+namespace bimaps {
+namespace relation {
+namespace support {
+
+template< class Tag, class Relation >
+struct data_extractor_implementation;
+
+template< class Relation >
+struct data_extractor_implementation< member_at::left, Relation > :
+    public std::unary_function<Relation,BOOST_DEDUCED_TYPENAME Relation::left_value_type>
+{
+    BOOST_DEDUCED_TYPENAME Relation::left_value_type const &
+        operator()(Relation const & rel) const
+    {
+        return rel.left;
+    }
+
+    BOOST_DEDUCED_TYPENAME Relation::left_value_type &
+        operator()(Relation       & rel) const
+    {
+        return rel.left;
+    }
+};
+
+template< class Relation >
+struct data_extractor_implementation< member_at::right, Relation > :
+    public std::unary_function<Relation,BOOST_DEDUCED_TYPENAME Relation::right_value_type>
+{
+    BOOST_DEDUCED_TYPENAME Relation::right_value_type const & 
+        operator()(Relation const & rel) const
+    {
+        return rel.right;
+    }
+
+    BOOST_DEDUCED_TYPENAME Relation::right_value_type & 
+        operator()(Relation       & rel) const
+    {
+        return rel.right;
+    }
+};
+
+template< class Tag, class Relation >
+struct data_extractor
+{
+    typedef data_extractor_implementation
+    <
+        BOOST_DEDUCED_TYPENAME member_with_tag<Tag,Relation>::type,
+        Relation
+
+    > type;
+};
+
+template< class Relation >
+struct both_keys_extractor
+{
+    typedef BOOST_DEDUCED_TYPENAME Relation::storage_base result_type;
+
+     const result_type & operator()(const Relation & rel) const
+    {
+        return rel;
+    }
+
+    result_type & operator()( Relation & rel) const
+    {
+        return rel;
+    }
+};
+
+} // namespace support
+} // namespace relation
+} // namespace bimaps
+} // namespace boost
+
+#endif // BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES
+
+#endif // BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
+