| //======================================================================= |
| // Copyright 2002 Indiana University. |
| // 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_DAG_SHORTEST_PATHS_HPP |
| #define BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP |
| |
| #include <boost/graph/topological_sort.hpp> |
| #include <boost/graph/dijkstra_shortest_paths.hpp> |
| |
| // single-source shortest paths for a Directed Acyclic Graph (DAG) |
| |
| namespace boost { |
| |
| // Initalize distances and call depth first search |
| template <class VertexListGraph, class DijkstraVisitor, |
| class DistanceMap, class WeightMap, class ColorMap, |
| class PredecessorMap, |
| class Compare, class Combine, |
| class DistInf, class DistZero> |
| inline void |
| dag_shortest_paths |
| (const VertexListGraph& g, |
| typename graph_traits<VertexListGraph>::vertex_descriptor s, |
| DistanceMap distance, WeightMap weight, ColorMap color, |
| PredecessorMap pred, |
| DijkstraVisitor vis, Compare compare, Combine combine, |
| DistInf inf, DistZero zero) |
| { |
| typedef typename graph_traits<VertexListGraph>::vertex_descriptor Vertex; |
| std::vector<Vertex> rev_topo_order; |
| rev_topo_order.reserve(num_vertices(g)); |
| |
| // Call 'depth_first_visit', not 'topological_sort', because we don't |
| // want to traverse the entire graph, only vertices reachable from 's', |
| // and 'topological_sort' will traverse everything. The logic below |
| // is the same as for 'topological_sort', only we call 'depth_first_visit' |
| // and 'topological_sort' calls 'depth_first_search'. |
| topo_sort_visitor<std::back_insert_iterator<std::vector<Vertex> > > |
| topo_visitor(std::back_inserter(rev_topo_order)); |
| depth_first_visit(g, s, topo_visitor, color); |
| |
| typename graph_traits<VertexListGraph>::vertex_iterator ui, ui_end; |
| for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui) { |
| put(distance, *ui, inf); |
| put(pred, *ui, *ui); |
| } |
| |
| put(distance, s, zero); |
| vis.discover_vertex(s, g); |
| typename std::vector<Vertex>::reverse_iterator i; |
| for (i = rev_topo_order.rbegin(); i != rev_topo_order.rend(); ++i) { |
| Vertex u = *i; |
| vis.examine_vertex(u, g); |
| typename graph_traits<VertexListGraph>::out_edge_iterator e, e_end; |
| for (boost::tie(e, e_end) = out_edges(u, g); e != e_end; ++e) { |
| vis.discover_vertex(target(*e, g), g); |
| bool decreased = relax(*e, g, weight, pred, distance, |
| combine, compare); |
| if (decreased) |
| vis.edge_relaxed(*e, g); |
| else |
| vis.edge_not_relaxed(*e, g); |
| } |
| vis.finish_vertex(u, g); |
| } |
| } |
| |
| namespace detail { |
| |
| // Defaults are the same as Dijkstra's algorithm |
| |
| // Handle Distance Compare, Combine, Inf and Zero defaults |
| template <class VertexListGraph, class DijkstraVisitor, |
| class DistanceMap, class WeightMap, class ColorMap, |
| class IndexMap, class Params> |
| inline void |
| dag_sp_dispatch2 |
| (const VertexListGraph& g, |
| typename graph_traits<VertexListGraph>::vertex_descriptor s, |
| DistanceMap distance, WeightMap weight, ColorMap color, IndexMap /*id*/, |
| DijkstraVisitor vis, const Params& params) |
| { |
| typedef typename property_traits<DistanceMap>::value_type D; |
| dummy_property_map p_map; |
| dag_shortest_paths |
| (g, s, distance, weight, color, |
| choose_param(get_param(params, vertex_predecessor), p_map), |
| vis, |
| choose_param(get_param(params, distance_compare_t()), std::less<D>()), |
| choose_param(get_param(params, distance_combine_t()), closed_plus<D>()), |
| choose_param(get_param(params, distance_inf_t()), |
| (std::numeric_limits<D>::max)()), |
| choose_param(get_param(params, distance_zero_t()), |
| D())); |
| } |
| |
| // Handle DistanceMap and ColorMap defaults |
| template <class VertexListGraph, class DijkstraVisitor, |
| class DistanceMap, class WeightMap, class ColorMap, |
| class IndexMap, class Params> |
| inline void |
| dag_sp_dispatch1 |
| (const VertexListGraph& g, |
| typename graph_traits<VertexListGraph>::vertex_descriptor s, |
| DistanceMap distance, WeightMap weight, ColorMap color, IndexMap id, |
| DijkstraVisitor vis, const Params& params) |
| { |
| typedef typename property_traits<WeightMap>::value_type T; |
| typename std::vector<T>::size_type n; |
| n = is_default_param(distance) ? num_vertices(g) : 1; |
| std::vector<T> distance_map(n); |
| n = is_default_param(color) ? num_vertices(g) : 1; |
| std::vector<default_color_type> color_map(n); |
| |
| dag_sp_dispatch2 |
| (g, s, |
| choose_param(distance, |
| make_iterator_property_map(distance_map.begin(), id, |
| distance_map[0])), |
| weight, |
| choose_param(color, |
| make_iterator_property_map(color_map.begin(), id, |
| color_map[0])), |
| id, vis, params); |
| } |
| |
| } // namespace detail |
| |
| template <class VertexListGraph, class Param, class Tag, class Rest> |
| inline void |
| dag_shortest_paths |
| (const VertexListGraph& g, |
| typename graph_traits<VertexListGraph>::vertex_descriptor s, |
| const bgl_named_params<Param,Tag,Rest>& params) |
| { |
| // assert that the graph is directed... |
| null_visitor null_vis; |
| detail::dag_sp_dispatch1 |
| (g, s, |
| get_param(params, vertex_distance), |
| choose_const_pmap(get_param(params, edge_weight), g, edge_weight), |
| get_param(params, vertex_color), |
| choose_const_pmap(get_param(params, vertex_index), g, vertex_index), |
| choose_param(get_param(params, graph_visitor), |
| make_dijkstra_visitor(null_vis)), |
| params); |
| } |
| |
| } // namespace boost |
| |
| #endif // BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP |