In common.h, define func_lib for function objects. In configure.ac, define HAVE_STD_FUNCTION and HAVE_BOOST_FUNCTION. Include function headers in ndnboost.
diff --git a/ndnboost/mpl/distance.hpp b/ndnboost/mpl/distance.hpp
new file mode 100644
index 0000000..3f1ef4a
--- /dev/null
+++ b/ndnboost/mpl/distance.hpp
@@ -0,0 +1,78 @@
+
+#ifndef BOOST_MPL_DISTANCE_HPP_INCLUDED
+#define BOOST_MPL_DISTANCE_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2000-2004
+//
+// 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: distance.hpp 49267 2008-10-11 06:19:02Z agurtovoy $
+// $Date: 2008-10-10 23:19:02 -0700 (Fri, 10 Oct 2008) $
+// $Revision: 49267 $
+
+#include <ndnboost/mpl/distance_fwd.hpp>
+#include <ndnboost/mpl/iter_fold.hpp>
+#include <ndnboost/mpl/iterator_range.hpp>
+#include <ndnboost/mpl/long.hpp>
+#include <ndnboost/mpl/next.hpp>
+#include <ndnboost/mpl/tag.hpp>
+#include <ndnboost/mpl/apply_wrap.hpp>
+#include <ndnboost/mpl/aux_/msvc_eti_base.hpp>
+#include <ndnboost/mpl/aux_/value_wknd.hpp>
+#include <ndnboost/mpl/aux_/na_spec.hpp>
+#include <ndnboost/mpl/aux_/config/forwarding.hpp>
+#include <ndnboost/mpl/aux_/config/static_constant.hpp>
+
+
+namespace ndnboost { namespace mpl {
+
+// default implementation for forward/bidirectional iterators
+template< typename Tag > struct distance_impl
+{
+ template< typename First, typename Last > struct apply
+#if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
+ : aux::msvc_eti_base< typename iter_fold<
+ iterator_range<First,Last>
+ , mpl::long_<0>
+ , next<>
+ >::type >
+ {
+#else
+ {
+ typedef typename iter_fold<
+ iterator_range<First,Last>
+ , mpl::long_<0>
+ , next<>
+ >::type type;
+
+ BOOST_STATIC_CONSTANT(long, value =
+ (iter_fold<
+ iterator_range<First,Last>
+ , mpl::long_<0>
+ , next<>
+ >::type::value)
+ );
+#endif
+ };
+};
+
+template<
+ typename BOOST_MPL_AUX_NA_PARAM(First)
+ , typename BOOST_MPL_AUX_NA_PARAM(Last)
+ >
+struct distance
+ : distance_impl< typename tag<First>::type >
+ ::template apply<First, Last>
+{
+ BOOST_MPL_AUX_LAMBDA_SUPPORT(2, distance, (First, Last))
+};
+
+BOOST_MPL_AUX_NA_SPEC(2, distance)
+
+}}
+
+#endif // BOOST_MPL_DISTANCE_HPP_INCLUDED