160 lines
6.1 KiB
C++
160 lines
6.1 KiB
C++
//=======================================================================
|
|
// 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;
|
|
D inf =
|
|
choose_param(get_param(params, distance_inf_t()),
|
|
(std::numeric_limits<D>::max)());
|
|
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>(inf)),
|
|
inf,
|
|
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
|