Ticket #7199: phx_at_key.patch

fusion.hpp

@@ -8 +8 @@
 #define PHOENIX_FUSION_HPP
 
 #include <boost/spirit/home/phoenix/fusion/at.hpp>
+#include <boost/spirit/home/phoenix/fusion/at_key.hpp>
 
 #endif

fusion/at_key.hpp

@@ +1 @@
+/*=============================================================================
+    Copyright (c) 2005-2008 Hartmut Kaiser
+    Copyright (c) 2005-2007 Joel de Guzman
+    Copyright (c) 2011      Michael Caisse
+
+    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)
+==============================================================================*/
+#ifndef PHOENIX_SEQUENCE_AT_KEY_HPP
+#define PHOENIX_SEQUENCE_AT_KEY_HPP
+
+#include <boost/fusion/include/at_key.hpp>
+#include <boost/spirit/home/phoenix/core/actor.hpp>
+#include <boost/spirit/home/phoenix/core/compose.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+namespace boost { namespace phoenix
+{
+    template <typename Key>
+    struct at_key_eval
+    {
+        template <typename Env, typename Tuple>
+        struct result
+        {
+            typedef typename Tuple::template result<Env>::type tuple;
+            typedef typename
+                fusion::result_of::at_key<
+                    typename remove_reference<tuple>::type, Key
+                >::type
+            type;
+        };
+
+        template <typename RT, typename Env, typename Tuple>
+        static RT
+        eval(Env const& env, Tuple const& t)
+        {
+            return fusion::at_key<Key>(t.eval(env));
+        }
+    };
+
+    template <typename Key, typename Tuple>
+    inline actor<typename as_composite<at_key_eval<Key>, Tuple>::type>
+    at_key(Tuple const& tup)
+    {
+        return compose<at_key_eval<Key> >(tup);
+    }
+
+}}
+
+#endif