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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> ));
- 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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