//======================================================================= | |
// 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 |