williamr@2: //
williamr@2: //=======================================================================
williamr@2: // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
williamr@2: // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //=======================================================================
williamr@2: //
williamr@2: #ifndef BOOST_GRAPH_NEIGHBOR_BREADTH_FIRST_SEARCH_HPP
williamr@2: #define BOOST_GRAPH_NEIGHBOR_BREADTH_FIRST_SEARCH_HPP
williamr@2: 
williamr@2: /*
williamr@2:   Neighbor Breadth First Search
williamr@2:   Like BFS, but traverses in-edges as well as out-edges.
williamr@2:   (for directed graphs only. use normal BFS for undirected graphs)
williamr@2: */
williamr@2: #include <boost/config.hpp>
williamr@2: #include <vector>
williamr@2: #include <boost/pending/queue.hpp>
williamr@2: #include <boost/graph/graph_traits.hpp>
williamr@2: #include <boost/graph/graph_concepts.hpp>
williamr@2: #include <boost/graph/visitors.hpp>
williamr@2: #include <boost/graph/named_function_params.hpp>
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2:   template <class Visitor, class Graph>
williamr@2:   struct NeighborBFSVisitorConcept {
williamr@2:     void constraints() {
williamr@2:       function_requires< CopyConstructibleConcept<Visitor> >();
williamr@2:       vis.initialize_vertex(u, g);
williamr@2:       vis.discover_vertex(u, g);
williamr@2:       vis.examine_vertex(u, g);
williamr@2:       vis.examine_out_edge(e, g);
williamr@2:       vis.examine_in_edge(e, g);
williamr@2:       vis.tree_out_edge(e, g);
williamr@2:       vis.tree_in_edge(e, g);
williamr@2:       vis.non_tree_out_edge(e, g);
williamr@2:       vis.non_tree_in_edge(e, g);
williamr@2:       vis.gray_target(e, g);
williamr@2:       vis.black_target(e, g);
williamr@2:       vis.gray_source(e, g);
williamr@2:       vis.black_source(e, g);
williamr@2:       vis.finish_vertex(u, g);
williamr@2:     }
williamr@2:     Visitor vis;
williamr@2:     Graph g;
williamr@2:     typename graph_traits<Graph>::vertex_descriptor u;
williamr@2:     typename graph_traits<Graph>::edge_descriptor e;
williamr@2:   };
williamr@2: 
williamr@2:   template <class Visitors = null_visitor>
williamr@2:   class neighbor_bfs_visitor {
williamr@2:   public:
williamr@2:     neighbor_bfs_visitor(Visitors vis = Visitors()) : m_vis(vis) { }
williamr@2: 
williamr@2:     template <class Vertex, class Graph>
williamr@2:     void initialize_vertex(Vertex u, Graph& g) {
williamr@2:       invoke_visitors(m_vis, u, g, on_initialize_vertex());      
williamr@2:     }
williamr@2:     template <class Vertex, class Graph>
williamr@2:     void discover_vertex(Vertex u, Graph& g) {
williamr@2:       invoke_visitors(m_vis, u, g, on_discover_vertex());      
williamr@2:     }
williamr@2:     template <class Vertex, class Graph>
williamr@2:     void examine_vertex(Vertex u, Graph& g) {
williamr@2:       invoke_visitors(m_vis, u, g, on_examine_vertex());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void examine_out_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_examine_edge());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void tree_out_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_tree_edge());      
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void non_tree_out_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_non_tree_edge());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void gray_target(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_gray_target());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void black_target(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_black_target());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void examine_in_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_examine_edge());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void tree_in_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_tree_edge());      
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void non_tree_in_edge(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_non_tree_edge());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void gray_source(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_gray_target());
williamr@2:     }
williamr@2:     template <class Edge, class Graph>
williamr@2:     void black_source(Edge e, Graph& g) {
williamr@2:       invoke_visitors(m_vis, e, g, on_black_target());
williamr@2:     }
williamr@2:     template <class Vertex, class Graph>
williamr@2:     void finish_vertex(Vertex u, Graph& g) {
williamr@2:       invoke_visitors(m_vis, u, g, on_finish_vertex());      
williamr@2:     }
williamr@2:   protected:
williamr@2:     Visitors m_vis;
williamr@2:   };
williamr@2: 
williamr@2:   template <class Visitors>
williamr@2:   neighbor_bfs_visitor<Visitors>
williamr@2:   make_neighbor_bfs_visitor(Visitors vis) {
williamr@2:     return neighbor_bfs_visitor<Visitors>(vis);
williamr@2:   }
williamr@2: 
williamr@2:   namespace detail {
williamr@2: 
williamr@2:     template <class BidirectionalGraph, class Buffer, class BFSVisitor, 
williamr@2:               class ColorMap>
williamr@2:     void neighbor_bfs_impl
williamr@2:       (const BidirectionalGraph& g, 
williamr@2:        typename graph_traits<BidirectionalGraph>::vertex_descriptor s, 
williamr@2:        Buffer& Q, BFSVisitor vis, ColorMap color)
williamr@2: 
williamr@2:     {
williamr@2:       function_requires< BidirectionalGraphConcept<BidirectionalGraph> >();
williamr@2:       typedef graph_traits<BidirectionalGraph> GTraits;
williamr@2:       typedef typename GTraits::vertex_descriptor Vertex;
williamr@2:       typedef typename GTraits::edge_descriptor Edge;
williamr@2:       function_requires< 
williamr@2:         NeighborBFSVisitorConcept<BFSVisitor, BidirectionalGraph> >();
williamr@2:       function_requires< ReadWritePropertyMapConcept<ColorMap, Vertex> >();
williamr@2:       typedef typename property_traits<ColorMap>::value_type ColorValue;
williamr@2:       typedef color_traits<ColorValue> Color;
williamr@2:       
williamr@2:       put(color, s, Color::gray());
williamr@2:       vis.discover_vertex(s, g);
williamr@2:       Q.push(s);
williamr@2:       while (! Q.empty()) {
williamr@2:         Vertex u = Q.top();
williamr@2:         Q.pop(); // pop before push to avoid problem if Q is priority_queue.
williamr@2:         vis.examine_vertex(u, g);
williamr@2: 
williamr@2:         typename GTraits::out_edge_iterator ei, ei_end;
williamr@2:         for (tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) {
williamr@2:           Edge e = *ei;
williamr@2:           vis.examine_out_edge(e, g);
williamr@2:           Vertex v = target(e, g);
williamr@2:           ColorValue v_color = get(color, v);
williamr@2:           if (v_color == Color::white()) {
williamr@2:             vis.tree_out_edge(e, g);
williamr@2:             put(color, v, Color::gray());
williamr@2:             vis.discover_vertex(v, g);
williamr@2:             Q.push(v);
williamr@2:           } else {
williamr@2:             vis.non_tree_out_edge(e, g);
williamr@2:             if (v_color == Color::gray())
williamr@2:               vis.gray_target(e, g);
williamr@2:             else
williamr@2:               vis.black_target(e, g);
williamr@2:           }
williamr@2:         } // for out-edges
williamr@2: 
williamr@2:         typename GTraits::in_edge_iterator in_ei, in_ei_end;
williamr@2:         for (tie(in_ei, in_ei_end) = in_edges(u, g); 
williamr@2:              in_ei != in_ei_end; ++in_ei) {
williamr@2:           Edge e = *in_ei;
williamr@2:           vis.examine_in_edge(e, g);
williamr@2:           Vertex v = source(e, g);
williamr@2:           ColorValue v_color = get(color, v);
williamr@2:           if (v_color == Color::white()) {
williamr@2:             vis.tree_in_edge(e, g);
williamr@2:             put(color, v, Color::gray());
williamr@2:             vis.discover_vertex(v, g);
williamr@2:             Q.push(v);
williamr@2:           } else {
williamr@2:             vis.non_tree_in_edge(e, g);
williamr@2:             if (v_color == Color::gray())
williamr@2:               vis.gray_source(e, g);
williamr@2:             else
williamr@2:               vis.black_source(e, g);
williamr@2:           }
williamr@2:         } // for in-edges
williamr@2: 
williamr@2:         put(color, u, Color::black());
williamr@2:         vis.finish_vertex(u, g);
williamr@2:       } // while
williamr@2:     }
williamr@2: 
williamr@2:     
williamr@2:     template <class VertexListGraph, class ColorMap, class BFSVisitor,
williamr@2:       class P, class T, class R>
williamr@2:     void neighbor_bfs_helper
williamr@2:       (VertexListGraph& g,
williamr@2:        typename graph_traits<VertexListGraph>::vertex_descriptor s,
williamr@2:        ColorMap color, 
williamr@2:        BFSVisitor vis,
williamr@2:        const bgl_named_params<P, T, R>& params)
williamr@2:     {
williamr@2:       typedef graph_traits<VertexListGraph> Traits;
williamr@2:       // Buffer default
williamr@2:       typedef typename Traits::vertex_descriptor Vertex;
williamr@2:       typedef boost::queue<Vertex> queue_t;
williamr@2:       queue_t Q;
williamr@2:       detail::wrap_ref<queue_t> Qref(Q);
williamr@2:       // Initialization
williamr@2:       typedef typename property_traits<ColorMap>::value_type ColorValue;
williamr@2:       typedef color_traits<ColorValue> Color;
williamr@2:       typename boost::graph_traits<VertexListGraph>::vertex_iterator i, i_end;
williamr@2:       for (tie(i, i_end) = vertices(g); i != i_end; ++i) {
williamr@2:         put(color, *i, Color::white());
williamr@2:         vis.initialize_vertex(*i, g);
williamr@2:       }
williamr@2:       neighbor_bfs_impl
williamr@2:         (g, s, 
williamr@2:          choose_param(get_param(params, buffer_param_t()), Qref).ref,
williamr@2:          vis, color);
williamr@2:     }
williamr@2: 
williamr@2:     //-------------------------------------------------------------------------
williamr@2:     // Choose between default color and color parameters. Using
williamr@2:     // function dispatching so that we don't require vertex index if
williamr@2:     // the color default is not being used.
williamr@2: 
williamr@2:     template <class ColorMap>
williamr@2:     struct neighbor_bfs_dispatch {
williamr@2:       template <class VertexListGraph, class P, class T, class R>
williamr@2:       static void apply
williamr@2:       (VertexListGraph& g,
williamr@2:        typename graph_traits<VertexListGraph>::vertex_descriptor s,
williamr@2:        const bgl_named_params<P, T, R>& params,
williamr@2:        ColorMap color)
williamr@2:       {
williamr@2:         neighbor_bfs_helper
williamr@2:           (g, s, color,
williamr@2:            choose_param(get_param(params, graph_visitor),
williamr@2:                         make_neighbor_bfs_visitor(null_visitor())),
williamr@2:            params);
williamr@2:       }
williamr@2:     };
williamr@2: 
williamr@2:     template <>
williamr@2:     struct neighbor_bfs_dispatch<detail::error_property_not_found> {
williamr@2:       template <class VertexListGraph, class P, class T, class R>
williamr@2:       static void apply
williamr@2:       (VertexListGraph& g,
williamr@2:        typename graph_traits<VertexListGraph>::vertex_descriptor s,
williamr@2:        const bgl_named_params<P, T, R>& params,
williamr@2:        detail::error_property_not_found)
williamr@2:       {
williamr@2:         std::vector<default_color_type> color_vec(num_vertices(g));
williamr@2:         null_visitor null_vis;
williamr@2:         
williamr@2:         neighbor_bfs_helper
williamr@2:           (g, s, 
williamr@2:            make_iterator_property_map
williamr@2:            (color_vec.begin(), 
williamr@2:             choose_const_pmap(get_param(params, vertex_index), 
williamr@2:                               g, vertex_index), color_vec[0]),
williamr@2:            choose_param(get_param(params, graph_visitor),
williamr@2:                         make_neighbor_bfs_visitor(null_vis)),
williamr@2:            params);
williamr@2:       }
williamr@2:     };
williamr@2: 
williamr@2:   } // namespace detail
williamr@2: 
williamr@2: 
williamr@2:   // Named Parameter Variant
williamr@2:   template <class VertexListGraph, class P, class T, class R>
williamr@2:   void neighbor_breadth_first_search
williamr@2:     (const VertexListGraph& g,
williamr@2:      typename graph_traits<VertexListGraph>::vertex_descriptor s,
williamr@2:      const bgl_named_params<P, T, R>& params)
williamr@2:   {
williamr@2:     // The graph is passed by *const* reference so that graph adaptors
williamr@2:     // (temporaries) can be passed into this function. However, the
williamr@2:     // graph is not really const since we may write to property maps
williamr@2:     // of the graph.
williamr@2:     VertexListGraph& ng = const_cast<VertexListGraph&>(g);
williamr@2:     typedef typename property_value< bgl_named_params<P,T,R>, 
williamr@2:       vertex_color_t>::type C;
williamr@2:     detail::neighbor_bfs_dispatch<C>::apply(ng, s, params, 
williamr@2:                                             get_param(params, vertex_color));
williamr@2:   }
williamr@2: 
williamr@2: 
williamr@2:   // This version does not initialize colors, user has to.
williamr@2: 
williamr@2:   template <class IncidenceGraph, class P, class T, class R>
williamr@2:   void neighbor_breadth_first_visit
williamr@2:     (IncidenceGraph& g,
williamr@2:      typename graph_traits<IncidenceGraph>::vertex_descriptor s,
williamr@2:      const bgl_named_params<P, T, R>& params)
williamr@2:   {
williamr@2:     typedef graph_traits<IncidenceGraph> Traits;
williamr@2:     // Buffer default
williamr@2:     typedef boost::queue<typename Traits::vertex_descriptor> queue_t;
williamr@2:     queue_t Q;
williamr@2:     detail::wrap_ref<queue_t> Qref(Q);
williamr@2: 
williamr@2:     detail::neighbor_bfs_impl
williamr@2:       (g, s,
williamr@2:        choose_param(get_param(params, buffer_param_t()), Qref).ref,
williamr@2:        choose_param(get_param(params, graph_visitor),
williamr@2:                     make_neighbor_bfs_visitor(null_visitor())),
williamr@2:        choose_pmap(get_param(params, vertex_color), g, vertex_color)
williamr@2:        );
williamr@2:   }
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_GRAPH_NEIGHBOR_BREADTH_FIRST_SEARCH_HPP
williamr@2: