//=======================================================================
// Copyright 2007 Aaron Windsor
//
// 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 __ADD_EDGE_VISITORS_HPP__
#define __ADD_EDGE_VISITORS_HPP__

#include <boost/property_map/property_map.hpp>

namespace boost
{

  struct default_add_edge_visitor
  {

    template <typename Graph, typename Vertex>
    void visit_vertex_pair(Vertex u, Vertex v, Graph& g)
    {
      add_edge(u,v,g);
    }

  };

  template<typename EdgeIndexMap>
  struct edge_index_update_visitor
  {

    typedef typename 
      property_traits<EdgeIndexMap>::value_type edge_index_value_t;

    edge_index_update_visitor(EdgeIndexMap em, 
                              edge_index_value_t next_index_available
                              ) : 
      m_em(em),
      m_next_index(next_index_available)
    {}
    
    template <typename Graph, typename Vertex>
    void visit_vertex_pair(Vertex u, Vertex v, Graph& g)
    {
      typedef typename graph_traits<Graph>::edge_descriptor edge_t;
      std::pair<edge_t, bool> return_value = add_edge(u,v,g);
      if (return_value.second)
        put( m_em, return_value.first, m_next_index++);
    }

  private:

    EdgeIndexMap m_em;
    edge_index_value_t m_next_index;

  };

} // namespace boost 

#endif //__ADD_EDGE_VISITORS_HPP__