Incomplete work for using Boost.Polygon to compute medial axis

xs/src/boost/mpl/fold.hpp

@@ -0,0 +1,48 @@
+
+#ifndef BOOST_MPL_FOLD_HPP_INCLUDED
+#define BOOST_MPL_FOLD_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2001-2004
+// Copyright David Abrahams 2001-2002
+//
+// 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)
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+// $Id: fold.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
+// $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
+// $Revision: 49267 $
+
+#include <boost/mpl/begin_end.hpp>
+#include <boost/mpl/O1_size.hpp>
+#include <boost/mpl/aux_/fold_impl.hpp>
+#include <boost/mpl/aux_/na_spec.hpp>
+#include <boost/mpl/aux_/lambda_support.hpp>
+
+namespace boost { namespace mpl {
+
+template<
+      typename BOOST_MPL_AUX_NA_PARAM(Sequence)
+    , typename BOOST_MPL_AUX_NA_PARAM(State)
+    , typename BOOST_MPL_AUX_NA_PARAM(ForwardOp)
+    >
+struct fold
+{
+    typedef typename aux::fold_impl<
+          ::boost::mpl::O1_size<Sequence>::value
+        , typename begin<Sequence>::type
+        , typename end<Sequence>::type
+        , State
+        , ForwardOp
+        >::state type;
+
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(3,fold,(Sequence,State,ForwardOp))
+};
+
+BOOST_MPL_AUX_NA_SPEC(3, fold)
+
+}}
+
+#endif // BOOST_MPL_FOLD_HPP_INCLUDED