//

//=======================================================================

// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.

// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek

//

// 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_GRAPH_DETAIL_EDGE_HPP

#define BOOST_GRAPH_DETAIL_EDGE_HPP

#if __GNUC__ < 3

#include <iostream>

#else

#include <iosfwd>

#endif

namespace boost {

  namespace  detail {

    template <typename Directed, typename Vertex>

    struct edge_base

    {

      inline edge_base() {} 

      inline edge_base(Vertex s, Vertex d)

        : m_source(s), m_target(d) { }

      Vertex m_source;

      Vertex m_target;

    };

    template <typename Directed, typename Vertex>

    class edge_desc_impl  : public edge_base<Directed,Vertex> {

      typedef edge_desc_impl                              self;

      typedef edge_base<Directed,Vertex> Base;

    public: 

      typedef void                              property_type;

      inline edge_desc_impl() : m_eproperty(0) {} 

      inline edge_desc_impl(Vertex s, Vertex d, const property_type* eplug)

        : Base(s,d), m_eproperty(const_cast<property_type*>(eplug)) { }

      property_type* get_property() { return m_eproperty; }

      const property_type* get_property() const { return m_eproperty; }

      //  protected:

      property_type* m_eproperty;

    };

    template <class D, class V>

    inline bool

    operator==(const detail::edge_desc_impl<D,V>& a, 

               const detail::edge_desc_impl<D,V>& b)

    {

      return a.get_property() == b.get_property();

    }

    template <class D, class V>

    inline bool

    operator!=(const detail::edge_desc_impl<D,V>& a, 

               const detail::edge_desc_impl<D,V>& b)

    {

      return ! (a.get_property() == b.get_property());

    }

  } //namespace detail

} // namespace boost

namespace std {

#if __GNUC__ < 3

  template <class D, class V>

  std::ostream& 

  operator<<(std::ostream& os, const boost::detail::edge_desc_impl<D,V>& e)

  {

    return os << "(" << e.m_source << "," << e.m_target << ")";

  }

#else

  template <class Char, class Traits, class D, class V>

  std::basic_ostream<Char, Traits>& 

  operator<<(std::basic_ostream<Char, Traits>& os,

             const boost::detail::edge_desc_impl<D,V>& e)

  {

    return os << "(" << e.m_source << "," << e.m_target << ")";

  }

#endif

}

#endif // BOOST_GRAPH_DETAIL_DETAIL_EDGE_HPP