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diff --git a/boost/bimap/relation/detail/mutant.hpp b/boost/bimap/relation/detail/mutant.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/detail/mutant.hpp
+/// \brief Mutate functions to extract views of mutant classes.
+
+#ifndef BOOST_BIMAP_RELATION_DETAIL_MUTANT_HPP
+#define BOOST_BIMAP_RELATION_DETAIL_MUTANT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER>=1200)
+#pragma once
+#endif
+
+#include <boost/config.hpp>
+
+#include <boost/bimap/detail/debug/static_error.hpp>
+#include <boost/mpl/contains.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/utility.hpp>
+#include <boost/static_assert.hpp>
+#include <boost/type_traits/is_const.hpp>
+#include <boost/mpl/not.hpp>
+#include <boost/utility/enable_if.hpp>
+
+namespace boost {
+namespace bimaps {
+namespace relation {
+
+/// \brief Relation details, mutant idiom and symmetrical metafunctions builders.
+
+namespace detail {
+
+//@{
+/// \brief Converts a mutant class to a view with zero overhead.
+/**
+
+This function is a safe wrapper around reinterpret_cast. It checks at
+compile time that the desired view is supported by the mutant class.
+See also mutant, can_mutate_in.
+\ingroup mutant_group
+                                                                            **/
+
+
+template< class View, class Type >
+BOOST_DEDUCED_TYPENAME enable_if< mpl::not_< is_const< Type > >,
+
+View&
+
+>::type mutate( Type & m )
+{
+    BOOST_MPL_ASSERT((
+        ::boost::mpl::contains<BOOST_DEDUCED_TYPENAME Type::mutant_views,View>
+    ));
+    return *reinterpret_cast< View* >(boost::addressof(m));
+}
+
+template< class View, class Type >
+BOOST_DEDUCED_TYPENAME enable_if< is_const< Type >,
+
+const View&
+
+>::type mutate( Type & m )
+{
+    BOOST_MPL_ASSERT((
+        ::boost::mpl::contains<BOOST_DEDUCED_TYPENAME Type::mutant_views,View> 
+    ));
+    return *reinterpret_cast< const View* >(boost::addressof(m));
+}
+
+//@}
+
+} // namespace detail
+} // namespace relation
+} // namespace bimaps
+} // namespace boost
+
+#endif // BOOST_BIMAP_RELATION_DETAIL_MUTANT_HPP
+