creating branch for fusion 2.1

[SVN r40232]

include/boost/fusion/iterator/iterator_facade.hpp

@@ -0,0 +1,50 @@
+/*=============================================================================
+    Copyright (c) 2001-2006 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(FUSION_ITERATOR_FACADE_09252006_1011)
+#define FUSION_ITERATOR_FACADE_09252006_1011
+
+#include <boost/fusion/support/iterator_base.hpp>
+#include <boost/fusion/iterator/detail/advance.hpp>
+#include <boost/fusion/support/category_of.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/mpl/assert.hpp>
+
+namespace boost { namespace fusion
+{
+    struct iterator_facade_tag;
+
+    template <typename Derived, typename Category>
+    struct iterator_facade : iterator_base<Derived>
+    {
+        typedef iterator_facade_tag fusion_tag;
+        typedef Derived derived_type;
+        typedef Category category;
+
+        // default implementation
+        template <typename I1, typename I2>
+        struct equal_to // default implementation
+            : is_same<
+                typename I1::derived_type
+              , typename I2::derived_type
+            >
+        {};
+
+        // default implementation
+        template <typename Iterator, typename N>
+        struct advance :
+            mpl::if_c<
+                (N::value > 0)
+              , advance_detail::forward<Iterator, N::value>
+              , advance_detail::backward<Iterator, N::value>
+            >::type
+        {
+            BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
+        };
+    };
+}}
+
+#endif