make fold aware of segments

[SVN r73906]

include/boost/fusion/algorithm/iteration/fold_fwd.hpp

@@ -0,0 +1,52 @@
+/*=============================================================================
+    Copyright (c) 2011 Eric Niebler
+
+    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 BOOST_FUSION_ALGORITHM_ITERATION_FOLD_FWD_HPP
+#define BOOST_FUSION_ALGORITHM_ITERATION_FOLD_FWD_HPP
+
+namespace boost { namespace fusion
+{
+    namespace result_of
+    {
+        template<typename Seq, typename State, typename F>
+        struct fold;
+    }
+
+    template<typename Seq, typename State, typename F>
+    typename result_of::fold<
+        Seq
+      , State const
+      , F
+    >::type
+    fold(Seq& seq, State const& state, F f);
+
+    template<typename Seq, typename State, typename F>
+    typename result_of::fold<
+        Seq const
+      , State const
+      , F
+    >::type
+    fold(Seq const& seq, State const& state, F f);
+
+    template<typename Seq, typename State, typename F>
+    typename result_of::fold<
+        Seq
+      , State const
+      , F
+    >::type
+    fold(Seq& seq, State& state, F f);
+
+    template<typename Seq, typename State, typename F>
+    typename result_of::fold<
+        Seq const
+      , State const
+      , F
+    >::type
+    fold(Seq const& seq, State& state, F f);
+}}
+
+#endif