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+/*=============================================================================
+ Copyright (c) 2001-2013 Joel de Guzman
+
+ 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)
+==============================================================================*/
+#if !defined(BOOST_FUSION_MAP_DETAIL_VALUE_AT_KEY_IMPL_02042013_0821)
+#define BOOST_FUSION_MAP_DETAIL_VALUE_AT_KEY_IMPL_02042013_0821
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/support/detail/access.hpp>
+#include <boost/type_traits/is_const.hpp>
+#include <boost/mpl/at.hpp>
+#include <boost/mpl/identity.hpp>
+
+namespace boost { namespace fusion
+{
+ struct map_tag;
+
+ namespace extension
+ {
+ template <typename Tag>
+ struct value_at_key_impl;
+
+ template <>
+ struct value_at_key_impl<map_tag>
+ {
+ template <typename Sequence, typename Key>
+ struct apply
+ {
+ typedef
+ decltype(std::declval<Sequence>().get_val(mpl::identity<Key>()))
+ type;
+ };
+ };
+ }
+}}
+
+#endif