//

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

 // 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_UNDIRECTED_DFS_HPP

 #define BOOST_GRAPH_UNDIRECTED_DFS_HPP

 #include <boost/graph/depth_first_search.hpp>

 #include <vector>

 namespace boost {

   namespace detail {

 // Define BOOST_RECURSIVE_DFS to use older, recursive version.

 // It is retained for a while in order to perform performance

 // comparison.

 #ifndef BOOST_RECURSIVE_DFS

     template <typename IncidenceGraph, typename DFSVisitor, 

               typename VertexColorMap, typename EdgeColorMap>

     void undir_dfv_impl

       (const IncidenceGraph& g,

        typename graph_traits<IncidenceGraph>::vertex_descriptor u, 

        DFSVisitor& vis,

        VertexColorMap vertex_color,

        EdgeColorMap edge_color)

     {

       function_requires<IncidenceGraphConcept<IncidenceGraph> >();

       function_requires<DFSVisitorConcept<DFSVisitor, IncidenceGraph> >();

       typedef typename graph_traits<IncidenceGraph>::vertex_descriptor Vertex;

       typedef typename graph_traits<IncidenceGraph>::edge_descriptor Edge;

       function_requires<ReadWritePropertyMapConcept<VertexColorMap,Vertex> >();

       function_requires<ReadWritePropertyMapConcept<EdgeColorMap,Edge> >();

       typedef typename property_traits<VertexColorMap>::value_type ColorValue;

       typedef typename property_traits<EdgeColorMap>::value_type EColorValue;

       function_requires< ColorValueConcept<ColorValue> >();

       function_requires< ColorValueConcept<EColorValue> >();

       typedef color_traits<ColorValue> Color;

       typedef color_traits<EColorValue> EColor;

       typedef typename graph_traits<IncidenceGraph>::out_edge_iterator Iter;

       typedef std::pair<Vertex, std::pair<Iter, Iter> > VertexInfo;

       std::vector<VertexInfo> stack;

       put(vertex_color, u, Color::gray());

       vis.discover_vertex(u, g);

       stack.push_back(std::make_pair(u, out_edges(u, g)));

       while (!stack.empty()) {

         VertexInfo& back = stack.back();

         u = back.first;

         Iter ei, ei_end;

         tie(ei, ei_end) = back.second;

         stack.pop_back();

         while (ei != ei_end) {

           Vertex v = target(*ei, g);

           vis.examine_edge(*ei, g);

           ColorValue v_color = get(vertex_color, v);

           EColorValue uv_color = get(edge_color, *ei);

           put(edge_color, *ei, EColor::black());

           if (v_color == Color::white()) {

             vis.tree_edge(*ei, g);

             stack.push_back(std::make_pair(u, std::make_pair(++ei, ei_end)));

             u = v;

             put(vertex_color, u, Color::gray());

             vis.discover_vertex(u, g);

             tie(ei, ei_end) = out_edges(u, g);

           } else if (v_color == Color::gray()) {

             if (uv_color == EColor::white()) vis.back_edge(*ei, g);

             ++ei;

           } else { // if (v_color == Color::black())

             ++ei;

           }

         }

         put(vertex_color, u, Color::black());

         vis.finish_vertex(u, g);

       }

     }

 #else // BOOST_RECURSIVE_DFS

     template <typename IncidenceGraph, typename DFSVisitor, 

               typename VertexColorMap, typename EdgeColorMap>

     void undir_dfv_impl

       (const IncidenceGraph& g,

        typename graph_traits<IncidenceGraph>::vertex_descriptor u, 

        DFSVisitor& vis,  // pass-by-reference here, important!

        VertexColorMap vertex_color,

        EdgeColorMap edge_color)

     {

       function_requires<IncidenceGraphConcept<IncidenceGraph> >();

       function_requires<DFSVisitorConcept<DFSVisitor, IncidenceGraph> >();

       typedef typename graph_traits<IncidenceGraph>::vertex_descriptor Vertex;

       typedef typename graph_traits<IncidenceGraph>::edge_descriptor Edge;

       function_requires<ReadWritePropertyMapConcept<VertexColorMap,Vertex> >();

       function_requires<ReadWritePropertyMapConcept<EdgeColorMap,Edge> >();

       typedef typename property_traits<VertexColorMap>::value_type ColorValue;

       typedef typename property_traits<EdgeColorMap>::value_type EColorValue;

       function_requires< ColorValueConcept<ColorValue> >();

       function_requires< ColorValueConcept<EColorValue> >();

       typedef color_traits<ColorValue> Color;

       typedef color_traits<EColorValue> EColor;

       typename graph_traits<IncidenceGraph>::out_edge_iterator ei, ei_end;

       put(vertex_color, u, Color::gray());   vis.discover_vertex(u, g);

       for (tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) {

         Vertex v = target(*ei, g);           vis.examine_edge(*ei, g);

         ColorValue v_color = get(vertex_color, v);

         EColorValue uv_color = get(edge_color, *ei);

         put(edge_color, *ei, EColor::black());

         if (v_color == Color::white()) {     vis.tree_edge(*ei, g);

           undir_dfv_impl(g, v, vis, vertex_color, edge_color);

         } else if (v_color == Color::gray() && uv_color == EColor::white())

                                              vis.back_edge(*ei, g);

       }

       put(vertex_color, u, Color::black());  vis.finish_vertex(u, g);

     }

 #endif // ! BOOST_RECURSIVE_DFS

   } // namespace detail

   template <typename Graph, typename DFSVisitor, 

             typename VertexColorMap, typename EdgeColorMap, 

             typename Vertex>

   void

   undirected_dfs(const Graph& g, DFSVisitor vis, 

                  VertexColorMap vertex_color, EdgeColorMap edge_color,

                  Vertex start_vertex)

   {

     function_requires<DFSVisitorConcept<DFSVisitor, Graph> >();

       function_requires<EdgeListGraphConcept<Graph> >();

     typedef typename property_traits<VertexColorMap>::value_type ColorValue;

     typedef color_traits<ColorValue> Color;

     typename graph_traits<Graph>::vertex_iterator ui, ui_end;

     for (tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui) {

       put(vertex_color, *ui, Color::white());   vis.initialize_vertex(*ui, g);

     }

     typename graph_traits<Graph>::edge_iterator ei, ei_end;

     for (tie(ei, ei_end) = edges(g); ei != ei_end; ++ei)

       put(edge_color, *ei, Color::white());

     if (start_vertex != *vertices(g).first){ vis.start_vertex(start_vertex, g);

       detail::undir_dfv_impl(g, start_vertex, vis, vertex_color, edge_color);

     }

     for (tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui) {

       ColorValue u_color = get(vertex_color, *ui);

       if (u_color == Color::white()) {       vis.start_vertex(*ui, g);

         detail::undir_dfv_impl(g, *ui, vis, vertex_color, edge_color);

       }

     }

   }

   template <typename Graph, typename DFSVisitor, typename VertexColorMap,

     typename EdgeColorMap>

   void

   undirected_dfs(const Graph& g, DFSVisitor vis, 

                  VertexColorMap vertex_color, EdgeColorMap edge_color)

   {

     undirected_dfs(g, vis, vertex_color, edge_color, *vertices(g).first);

   }

   namespace detail {

     template <typename VertexColorMap>

     struct udfs_dispatch {

       template <typename Graph, typename Vertex, 

                 typename DFSVisitor, typename EdgeColorMap,

                 typename P, typename T, typename R>

       static void

       apply(const Graph& g, DFSVisitor vis, Vertex start_vertex,

             const bgl_named_params<P, T, R>&,

             EdgeColorMap edge_color,

             VertexColorMap vertex_color)

       {

         undirected_dfs(g, vis, vertex_color, edge_color, start_vertex);

       }

     };

     template <>

     struct udfs_dispatch<detail::error_property_not_found> {

       template <typename Graph, typename Vertex, typename DFSVisitor,

                 typename EdgeColorMap,

                 typename P, typename T, typename R>

       static void

       apply(const Graph& g, DFSVisitor vis, Vertex start_vertex,

             const bgl_named_params<P, T, R>& params,

             EdgeColorMap edge_color,

             detail::error_property_not_found)

       {

         std::vector<default_color_type> color_vec(num_vertices(g));

         default_color_type c = white_color; // avoid warning about un-init

         undirected_dfs

           (g, vis, make_iterator_property_map

            (color_vec.begin(),

             choose_const_pmap(get_param(params, vertex_index),

                               g, vertex_index), c),

            edge_color,

            start_vertex);

       }

     };

   } // namespace detail

   // Named Parameter Variant

   template <typename Graph, typename P, typename T, typename R>

   void

   undirected_dfs(const Graph& g, 

                  const bgl_named_params<P, T, R>& params)

   {

     typedef typename property_value< bgl_named_params<P, T, R>, 

       vertex_color_t>::type C;

     detail::udfs_dispatch<C>::apply

       (g,

        choose_param(get_param(params, graph_visitor),

                     make_dfs_visitor(null_visitor())),

        choose_param(get_param(params, root_vertex_t()),

                     *vertices(g).first),

        params,

        get_param(params, edge_color),

        get_param(params, vertex_color)

        );

   }

   template <typename IncidenceGraph, typename DFSVisitor, 

     typename VertexColorMap, typename EdgeColorMap>

   void undirected_depth_first_visit

     (const IncidenceGraph& g,

      typename graph_traits<IncidenceGraph>::vertex_descriptor u, 

      DFSVisitor vis, VertexColorMap vertex_color, EdgeColorMap edge_color)

   {

     detail::undir_dfv_impl(g, u, vis, vertex_color, edge_color);

   }

 } // namespace boost

 #endif