Added boost header

test/external/boost/fusion/sequence/intrinsic/value_at_key.hpp

@@ -0,0 +1,66 @@
+/*=============================================================================
+    Copyright (c) 2001-2011 Joel de Guzman
+    Copyright (c) 2006 Dan Marsden
+
+    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(FUSION_VALUE_AT_KEY_05052005_0229)
+#define FUSION_VALUE_AT_KEY_05052005_0229
+
+#include <boost/mpl/int.hpp>
+#include <boost/fusion/sequence/intrinsic_fwd.hpp>
+#include <boost/fusion/iterator/value_of_data.hpp>
+#include <boost/fusion/algorithm/query/find.hpp>
+#include <boost/fusion/support/tag_of.hpp>
+
+namespace boost { namespace fusion
+{
+    // Special tags:
+    struct sequence_facade_tag;
+    struct boost_array_tag; // boost::array tag
+    struct mpl_sequence_tag; // mpl sequence tag
+    struct std_pair_tag; // std::pair tag
+
+    namespace extension
+    {
+        template <typename Tag>
+        struct value_at_key_impl
+        {
+            template <typename Seq, typename Key>
+            struct apply
+              : result_of::value_of_data<
+                    typename result_of::find<Seq, Key>::type
+                >
+            {};
+        };
+
+        template <>
+        struct value_at_key_impl<sequence_facade_tag>
+        {
+            template <typename Sequence, typename Key>
+            struct apply : Sequence::template value_at_key<Sequence, Key> {};
+        };
+
+        template <>
+        struct value_at_key_impl<boost_array_tag>;
+
+        template <>
+        struct value_at_key_impl<mpl_sequence_tag>;
+
+        template <>
+        struct value_at_key_impl<std_pair_tag>;
+    }
+    
+    namespace result_of
+    {
+        template <typename Sequence, typename N>
+        struct value_at_key
+            : extension::value_at_key_impl<typename detail::tag_of<Sequence>::type>::
+                template apply<Sequence, N>
+        {};
+    }
+}}
+
+#endif
+