227 lines
8.0 KiB
C++
227 lines
8.0 KiB
C++
//
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//=======================================================================
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// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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//
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/*
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This file implements the function
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template <class EdgeListGraph, class Size, class P, class T, class R>
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N,
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const bgl_named_params<P, T, R>& params)
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*/
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#ifndef BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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#define BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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#include <boost/config.hpp>
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#include <boost/graph/graph_traits.hpp>
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#include <boost/graph/graph_concepts.hpp>
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#include <boost/graph/properties.hpp>
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#include <boost/graph/relax.hpp>
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#include <boost/graph/visitors.hpp>
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#include <boost/graph/named_function_params.hpp>
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#include <boost/concept/assert.hpp>
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namespace boost
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{
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template < class Visitor, class Graph > struct BellmanFordVisitorConcept
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{
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void constraints()
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{
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BOOST_CONCEPT_ASSERT((CopyConstructibleConcept< Visitor >));
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vis.examine_edge(e, g);
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vis.edge_relaxed(e, g);
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vis.edge_not_relaxed(e, g);
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vis.edge_minimized(e, g);
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vis.edge_not_minimized(e, g);
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}
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Visitor vis;
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Graph g;
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typename graph_traits< Graph >::edge_descriptor e;
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};
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template < class Visitors = null_visitor > class bellman_visitor
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{
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public:
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bellman_visitor() {}
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bellman_visitor(Visitors vis) : m_vis(vis) {}
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template < class Edge, class Graph > void examine_edge(Edge u, Graph& g)
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{
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invoke_visitors(m_vis, u, g, on_examine_edge());
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}
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template < class Edge, class Graph > void edge_relaxed(Edge u, Graph& g)
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{
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invoke_visitors(m_vis, u, g, on_edge_relaxed());
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}
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template < class Edge, class Graph > void edge_not_relaxed(Edge u, Graph& g)
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{
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invoke_visitors(m_vis, u, g, on_edge_not_relaxed());
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}
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template < class Edge, class Graph > void edge_minimized(Edge u, Graph& g)
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{
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invoke_visitors(m_vis, u, g, on_edge_minimized());
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}
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template < class Edge, class Graph >
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void edge_not_minimized(Edge u, Graph& g)
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{
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invoke_visitors(m_vis, u, g, on_edge_not_minimized());
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}
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protected:
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Visitors m_vis;
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};
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template < class Visitors >
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bellman_visitor< Visitors > make_bellman_visitor(Visitors vis)
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{
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return bellman_visitor< Visitors >(vis);
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}
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typedef bellman_visitor<> default_bellman_visitor;
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template < class EdgeListGraph, class Size, class WeightMap,
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class PredecessorMap, class DistanceMap, class BinaryFunction,
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class BinaryPredicate, class BellmanFordVisitor >
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N, WeightMap weight,
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PredecessorMap pred, DistanceMap distance, BinaryFunction combine,
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BinaryPredicate compare, BellmanFordVisitor v)
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{
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BOOST_CONCEPT_ASSERT((EdgeListGraphConcept< EdgeListGraph >));
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typedef graph_traits< EdgeListGraph > GTraits;
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typedef typename GTraits::edge_descriptor Edge;
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typedef typename GTraits::vertex_descriptor Vertex;
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BOOST_CONCEPT_ASSERT((ReadWritePropertyMapConcept< DistanceMap, Vertex >));
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BOOST_CONCEPT_ASSERT((ReadablePropertyMapConcept< WeightMap, Edge >));
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typename GTraits::edge_iterator i, end;
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for (Size k = 0; k < N; ++k)
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{
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bool at_least_one_edge_relaxed = false;
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for (boost::tie(i, end) = edges(g); i != end; ++i)
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{
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v.examine_edge(*i, g);
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if (relax(*i, g, weight, pred, distance, combine, compare))
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{
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at_least_one_edge_relaxed = true;
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v.edge_relaxed(*i, g);
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}
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else
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v.edge_not_relaxed(*i, g);
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}
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if (!at_least_one_edge_relaxed)
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break;
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}
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for (boost::tie(i, end) = edges(g); i != end; ++i)
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if (compare(combine(get(distance, source(*i, g)), get(weight, *i)),
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get(distance, target(*i, g))))
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{
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v.edge_not_minimized(*i, g);
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return false;
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}
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else
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v.edge_minimized(*i, g);
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return true;
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}
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namespace detail
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{
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template < typename VertexAndEdgeListGraph, typename Size,
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typename WeightMap, typename PredecessorMap, typename DistanceMap,
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typename P, typename T, typename R >
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bool bellman_dispatch2(VertexAndEdgeListGraph& g,
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typename graph_traits< VertexAndEdgeListGraph >::vertex_descriptor s,
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Size N, WeightMap weight, PredecessorMap pred, DistanceMap distance,
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const bgl_named_params< P, T, R >& params)
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{
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typedef typename property_traits< DistanceMap >::value_type D;
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bellman_visitor<> null_vis;
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typedef typename property_traits< WeightMap >::value_type weight_type;
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typename graph_traits< VertexAndEdgeListGraph >::vertex_iterator v,
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v_end;
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for (boost::tie(v, v_end) = vertices(g); v != v_end; ++v)
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{
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put(distance, *v, (std::numeric_limits< weight_type >::max)());
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put(pred, *v, *v);
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}
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put(distance, s, weight_type(0));
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return bellman_ford_shortest_paths(g, N, weight, pred, distance,
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choose_param(
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get_param(params, distance_combine_t()), closed_plus< D >()),
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choose_param(
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get_param(params, distance_compare_t()), std::less< D >()),
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choose_param(get_param(params, graph_visitor), null_vis));
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}
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template < typename VertexAndEdgeListGraph, typename Size,
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typename WeightMap, typename PredecessorMap, typename DistanceMap,
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typename P, typename T, typename R >
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bool bellman_dispatch2(VertexAndEdgeListGraph& g, param_not_found, Size N,
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WeightMap weight, PredecessorMap pred, DistanceMap distance,
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const bgl_named_params< P, T, R >& params)
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{
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typedef typename property_traits< DistanceMap >::value_type D;
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bellman_visitor<> null_vis;
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return bellman_ford_shortest_paths(g, N, weight, pred, distance,
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choose_param(
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get_param(params, distance_combine_t()), closed_plus< D >()),
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choose_param(
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get_param(params, distance_compare_t()), std::less< D >()),
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choose_param(get_param(params, graph_visitor), null_vis));
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}
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template < class EdgeListGraph, class Size, class WeightMap,
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class DistanceMap, class P, class T, class R >
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bool bellman_dispatch(EdgeListGraph& g, Size N, WeightMap weight,
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DistanceMap distance, const bgl_named_params< P, T, R >& params)
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{
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dummy_property_map dummy_pred;
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return detail::bellman_dispatch2(g, get_param(params, root_vertex_t()),
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N, weight,
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choose_param(get_param(params, vertex_predecessor), dummy_pred),
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distance, params);
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}
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} // namespace detail
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template < class EdgeListGraph, class Size, class P, class T, class R >
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bool bellman_ford_shortest_paths(
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EdgeListGraph& g, Size N, const bgl_named_params< P, T, R >& params)
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{
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return detail::bellman_dispatch(g, N,
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
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choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
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params);
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}
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template < class EdgeListGraph, class Size >
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N)
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{
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bgl_named_params< int, int > params(0);
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return bellman_ford_shortest_paths(g, N, params);
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}
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template < class VertexAndEdgeListGraph, class P, class T, class R >
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bool bellman_ford_shortest_paths(
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VertexAndEdgeListGraph& g, const bgl_named_params< P, T, R >& params)
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{
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BOOST_CONCEPT_ASSERT((VertexListGraphConcept< VertexAndEdgeListGraph >));
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return detail::bellman_dispatch(g, num_vertices(g),
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
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choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
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params);
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}
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} // namespace boost
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#endif // BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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