boost/graph/overloading.hpp

// Copyright 2004 The Trustees of Indiana University.
// 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)
//  Authors: Douglas Gregor
//           Andrew Lumsdaine
//
// This file contains helps that enable concept-based overloading
// within the Boost Graph Library.
//
#ifndef BOOST_GRAPH_OVERLOADING_HPP
#define BOOST_GRAPH_OVERLOADING_HPP
#include <boost/type_traits/is_base_and_derived.hpp>
#include <boost/utility/enable_if.hpp>
namespace boost {  namespace graph { namespace detail {
struct no_parameter {};
} } } // end namespace boost::graph::detail
#ifndef BOOST_NO_SFINAE
#define BOOST_GRAPH_ENABLE_IF_MODELS(Graph, Tag, Type)               \
  typename enable_if_c<(is_base_and_derived<                         \
                          Tag,                                       \
                          typename graph_traits<Graph>::traversal_category>::value), \
                       Type>::type
#define BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, Tag)                   \
  , BOOST_GRAPH_ENABLE_IF_MODELS(Graph, Tag,                            \
                                 ::boost::graph::detail::no_parameter)  \
    = ::boost::graph::detail::no_parameter()
#else
#define BOOST_GRAPH_ENABLE_IF_MODELS(Graph, Tag, Type) Type
#define BOOST_GRAPH_ENABLE_IF_MODELS_PARM(Graph, Tag)
#endif // no SFINAE support
#endif // BOOST_GRAPH_OVERLOADING_HPP