adding fusion docs and tests

[SVN r34920]

example/extension/detail/value_of_impl.hpp

@@ -0,0 +1,48 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2006 Dan Marsden
+
+    Use, modification and distribution is subject to 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_VALUE_OF_IMPL_20060223_1905)
+#define BOOST_FUSION_VALUE_OF_IMPL_20060223_1905
+
+#include <string>
+
+namespace boost { namespace fusion {
+
+    struct example_struct_iterator_tag;
+
+    template<typename Struct, int Pos>
+    struct example_struct_iterator;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct value_of_impl;
+
+        template<>
+        struct value_of_impl<example_struct_iterator_tag>
+        {
+            template<typename Iterator>
+            struct apply;
+
+            template<typename Struct>
+            struct apply<example_struct_iterator<Struct, 0> >
+            {
+                typedef std::string type;
+            };
+
+            template<typename Struct>
+            struct apply<example_struct_iterator<Struct, 1> >
+            {
+                typedef int type;
+            };
+
+        };
+    }
+}}
+
+#endif