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//
//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// 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)
//=======================================================================
//
/*
This file implements the function
template <class EdgeListGraph, class Size, class P, class T, class R>
bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N,
const bgl_named_params<P, T, R>& params)
*/
#ifndef BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
#define BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
#include <boost/config.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/graph_concepts.hpp>
#include <boost/graph/properties.hpp>
#include <boost/graph/relax.hpp>
#include <boost/graph/visitors.hpp>
#include <boost/graph/named_function_params.hpp>
#include <boost/concept/assert.hpp>
namespace boost {
template <class Visitor, class Graph>
struct BellmanFordVisitorConcept {
void constraints() {
BOOST_CONCEPT_ASSERT(( CopyConstructibleConcept<Visitor> ));
vis.examine_edge(e, g);
vis.edge_relaxed(e, g);
vis.edge_not_relaxed(e, g);
vis.edge_minimized(e, g);
vis.edge_not_minimized(e, g);
}
Visitor vis;
Graph g;
typename graph_traits<Graph>::edge_descriptor e;
};
template <class Visitors = null_visitor>
class bellman_visitor {
public:
bellman_visitor() { }
bellman_visitor(Visitors vis) : m_vis(vis) { }
template <class Edge, class Graph>
void examine_edge(Edge u, Graph& g) {
invoke_visitors(m_vis, u, g, on_examine_edge());
}
template <class Edge, class Graph>
void edge_relaxed(Edge u, Graph& g) {
invoke_visitors(m_vis, u, g, on_edge_relaxed());
}
template <class Edge, class Graph>
void edge_not_relaxed(Edge u, Graph& g) {
invoke_visitors(m_vis, u, g, on_edge_not_relaxed());
}
template <class Edge, class Graph>
void edge_minimized(Edge u, Graph& g) {
invoke_visitors(m_vis, u, g, on_edge_minimized());
}
template <class Edge, class Graph>
void edge_not_minimized(Edge u, Graph& g) {
invoke_visitors(m_vis, u, g, on_edge_not_minimized());
}
protected:
Visitors m_vis;
};
template <class Visitors>
bellman_visitor<Visitors>
make_bellman_visitor(Visitors vis) {
return bellman_visitor<Visitors>(vis);
}
typedef bellman_visitor<> default_bellman_visitor;
template <class EdgeListGraph, class Size, class WeightMap,
class PredecessorMap, class DistanceMap,
class BinaryFunction, class BinaryPredicate,
class BellmanFordVisitor>
bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N,
WeightMap weight,
PredecessorMap pred,
DistanceMap distance,
BinaryFunction combine,
BinaryPredicate compare,
BellmanFordVisitor v)
{
BOOST_CONCEPT_ASSERT(( EdgeListGraphConcept<EdgeListGraph> ));
typedef graph_traits<EdgeListGraph> GTraits;
typedef typename GTraits::edge_descriptor Edge;
typedef typename GTraits::vertex_descriptor Vertex;
BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<DistanceMap, Vertex> ));
BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<WeightMap, Edge> ));
typedef typename property_traits<DistanceMap>::value_type D_value;
typedef typename property_traits<WeightMap>::value_type W_value;
typename GTraits::edge_iterator i, end;
for (Size k = 0; k < N; ++k) {
bool at_least_one_edge_relaxed = false;
for (boost::tie(i, end) = edges(g); i != end; ++i) {
v.examine_edge(*i, g);
if (relax(*i, g, weight, pred, distance, combine, compare)) {
at_least_one_edge_relaxed = true;
v.edge_relaxed(*i, g);
} else
v.edge_not_relaxed(*i, g);
}
if (!at_least_one_edge_relaxed)
break;
}
for (boost::tie(i, end) = edges(g); i != end; ++i)
if (compare(combine(get(distance, source(*i, g)), get(weight, *i)),
get(distance, target(*i,g))))
{
v.edge_not_minimized(*i, g);
return false;
} else
v.edge_minimized(*i, g);
return true;
}
namespace detail {
template<typename VertexAndEdgeListGraph, typename Size,
typename WeightMap, typename PredecessorMap, typename DistanceMap,
typename P, typename T, typename R>
bool
bellman_dispatch2
(VertexAndEdgeListGraph& g,
typename graph_traits<VertexAndEdgeListGraph>::vertex_descriptor s,
Size N, WeightMap weight, PredecessorMap pred, DistanceMap distance,
const bgl_named_params<P, T, R>& params)
{
typedef typename property_traits<DistanceMap>::value_type D;
bellman_visitor<> null_vis;
typedef typename property_traits<WeightMap>::value_type weight_type;
typename graph_traits<VertexAndEdgeListGraph>::vertex_iterator v, v_end;
for (boost::tie(v, v_end) = vertices(g); v != v_end; ++v) {
put(distance, *v, (std::numeric_limits<weight_type>::max)());
put(pred, *v, *v);
}
put(distance, s, weight_type(0));
return bellman_ford_shortest_paths
(g, N, weight, pred, distance,
choose_param(get_param(params, distance_combine_t()),
closed_plus<D>()),
choose_param(get_param(params, distance_compare_t()),
std::less<D>()),
choose_param(get_param(params, graph_visitor),
null_vis)
);
}
template<typename VertexAndEdgeListGraph, typename Size,
typename WeightMap, typename PredecessorMap, typename DistanceMap,
typename P, typename T, typename R>
bool
bellman_dispatch2
(VertexAndEdgeListGraph& g,
param_not_found,
Size N, WeightMap weight, PredecessorMap pred, DistanceMap distance,
const bgl_named_params<P, T, R>& params)
{
typedef typename property_traits<DistanceMap>::value_type D;
bellman_visitor<> null_vis;
return bellman_ford_shortest_paths
(g, N, weight, pred, distance,
choose_param(get_param(params, distance_combine_t()),
closed_plus<D>()),
choose_param(get_param(params, distance_compare_t()),
std::less<D>()),
choose_param(get_param(params, graph_visitor),
null_vis)
);
}
template <class EdgeListGraph, class Size, class WeightMap,
class DistanceMap, class P, class T, class R>
bool bellman_dispatch(EdgeListGraph& g, Size N,
WeightMap weight, DistanceMap distance,
const bgl_named_params<P, T, R>& params)
{
dummy_property_map dummy_pred;
return
detail::bellman_dispatch2
(g,
get_param(params, root_vertex_t()),
N, weight,
choose_param(get_param(params, vertex_predecessor), dummy_pred),
distance,
params);
}
} // namespace detail
template <class EdgeListGraph, class Size, class P, class T, class R>
bool bellman_ford_shortest_paths
(EdgeListGraph& g, Size N,
const bgl_named_params<P, T, R>& params)
{
return detail::bellman_dispatch
(g, N,
choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
params);
}
template <class EdgeListGraph, class Size>
bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N)
{
bgl_named_params<int,int> params(0);
return bellman_ford_shortest_paths(g, N, params);
}
template <class VertexAndEdgeListGraph, class P, class T, class R>
bool bellman_ford_shortest_paths
(VertexAndEdgeListGraph& g,
const bgl_named_params<P, T, R>& params)
{
BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<VertexAndEdgeListGraph> ));
return detail::bellman_dispatch
(g, num_vertices(g),
choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
params);
}
} // namespace boost
#endif // BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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