ceph/src/boost/boost/graph/dag_shortest_paths.hpp

   1 //=======================================================================
   2 // Copyright 2002 Indiana University.
   3 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
   4 //
   5 // Distributed under the Boost Software License, Version 1.0. (See
   6 // accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 //=======================================================================
   9
  10 #ifndef BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP
  11 #define BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP
  12
  13 #include <boost/graph/topological_sort.hpp>
  14 #include <boost/graph/dijkstra_shortest_paths.hpp>
  15
  16 // single-source shortest paths for a Directed Acyclic Graph (DAG)
  17
  18 namespace boost
  19 {
  20
  21 // Initalize distances and call depth first search
  22 template < class VertexListGraph, class DijkstraVisitor, class DistanceMap,
  23     class WeightMap, class ColorMap, class PredecessorMap, class Compare,
  24     class Combine, class DistInf, class DistZero >
  25 inline void dag_shortest_paths(const VertexListGraph& g,
  26     typename graph_traits< VertexListGraph >::vertex_descriptor s,
  27     DistanceMap distance, WeightMap weight, ColorMap color, PredecessorMap pred,
  28     DijkstraVisitor vis, Compare compare, Combine combine, DistInf inf,
  29     DistZero zero)
  30 {
  31     typedef typename graph_traits< VertexListGraph >::vertex_descriptor Vertex;
  32     std::vector< Vertex > rev_topo_order;
  33     rev_topo_order.reserve(num_vertices(g));
  34
  35     // Call 'depth_first_visit', not 'topological_sort', because we don't
  36     // want to traverse the entire graph, only vertices reachable from 's',
  37     // and 'topological_sort' will traverse everything. The logic below
  38     // is the same as for 'topological_sort', only we call 'depth_first_visit'
  39     // and 'topological_sort' calls 'depth_first_search'.
  40     topo_sort_visitor< std::back_insert_iterator< std::vector< Vertex > > >
  41         topo_visitor(std::back_inserter(rev_topo_order));
  42     depth_first_visit(g, s, topo_visitor, color);
  43
  44     typename graph_traits< VertexListGraph >::vertex_iterator ui, ui_end;
  45     for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
  46     {
  47         put(distance, *ui, inf);
  48         put(pred, *ui, *ui);
  49     }
  50
  51     put(distance, s, zero);
  52     vis.discover_vertex(s, g);
  53     typename std::vector< Vertex >::reverse_iterator i;
  54     for (i = rev_topo_order.rbegin(); i != rev_topo_order.rend(); ++i)
  55     {
  56         Vertex u = *i;
  57         vis.examine_vertex(u, g);
  58         typename graph_traits< VertexListGraph >::out_edge_iterator e, e_end;
  59         for (boost::tie(e, e_end) = out_edges(u, g); e != e_end; ++e)
  60         {
  61             vis.discover_vertex(target(*e, g), g);
  62             bool decreased
  63                 = relax(*e, g, weight, pred, distance, combine, compare);
  64             if (decreased)
  65                 vis.edge_relaxed(*e, g);
  66             else
  67                 vis.edge_not_relaxed(*e, g);
  68         }
  69         vis.finish_vertex(u, g);
  70     }
  71 }
  72
  73 namespace detail
  74 {
  75
  76     // Defaults are the same as Dijkstra's algorithm
  77
  78     // Handle Distance Compare, Combine, Inf and Zero defaults
  79     template < class VertexListGraph, class DijkstraVisitor, class DistanceMap,
  80         class WeightMap, class ColorMap, class IndexMap, class Params >
  81     inline void dag_sp_dispatch2(const VertexListGraph& g,
  82         typename graph_traits< VertexListGraph >::vertex_descriptor s,
  83         DistanceMap distance, WeightMap weight, ColorMap color, IndexMap /*id*/,
  84         DijkstraVisitor vis, const Params& params)
  85     {
  86         typedef typename property_traits< DistanceMap >::value_type D;
  87         dummy_property_map p_map;
  88         D inf = choose_param(get_param(params, distance_inf_t()),
  89             (std::numeric_limits< D >::max)());
  90         dag_shortest_paths(g, s, distance, weight, color,
  91             choose_param(get_param(params, vertex_predecessor), p_map), vis,
  92             choose_param(
  93                 get_param(params, distance_compare_t()), std::less< D >()),
  94             choose_param(
  95                 get_param(params, distance_combine_t()), closed_plus< D >(inf)),
  96             inf, choose_param(get_param(params, distance_zero_t()), D()));
  97     }
  98
  99     // Handle DistanceMap and ColorMap defaults
 100     template < class VertexListGraph, class DijkstraVisitor, class DistanceMap,
 101         class WeightMap, class ColorMap, class IndexMap, class Params >
 102     inline void dag_sp_dispatch1(const VertexListGraph& g,
 103         typename graph_traits< VertexListGraph >::vertex_descriptor s,
 104         DistanceMap distance, WeightMap weight, ColorMap color, IndexMap id,
 105         DijkstraVisitor vis, const Params& params)
 106     {
 107         typedef typename property_traits< WeightMap >::value_type T;
 108         typename std::vector< T >::size_type n;
 109         n = is_default_param(distance) ? num_vertices(g) : 1;
 110         std::vector< T > distance_map(n);
 111         n = is_default_param(color) ? num_vertices(g) : 1;
 112         std::vector< default_color_type > color_map(n);
 113
 114         dag_sp_dispatch2(g, s,
 115             choose_param(distance,
 116                 make_iterator_property_map(
 117                     distance_map.begin(), id, distance_map[0])),
 118             weight,
 119             choose_param(color,
 120                 make_iterator_property_map(
 121                     color_map.begin(), id, color_map[0])),
 122             id, vis, params);
 123     }
 124
 125 } // namespace detail
 126
 127 template < class VertexListGraph, class Param, class Tag, class Rest >
 128 inline void dag_shortest_paths(const VertexListGraph& g,
 129     typename graph_traits< VertexListGraph >::vertex_descriptor s,
 130     const bgl_named_params< Param, Tag, Rest >& params)
 131 {
 132     // assert that the graph is directed...
 133     null_visitor null_vis;
 134     detail::dag_sp_dispatch1(g, s, get_param(params, vertex_distance),
 135         choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
 136         get_param(params, vertex_color),
 137         choose_const_pmap(get_param(params, vertex_index), g, vertex_index),
 138         choose_param(
 139             get_param(params, graph_visitor), make_dijkstra_visitor(null_vis)),
 140         params);
 141 }
 142
 143 } // namespace boost
 144
 145 #endif // BOOST_GRAPH_DAG_SHORTEST_PATHS_HPP