boost/graph/prim_minimum_spanning_tree.hpp

0001 //=======================================================================
0002 // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
0003 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
0004 //
0005 // Distributed under the Boost Software License, Version 1.0. (See
0006 // accompanying file LICENSE_1_0.txt or copy at
0007 // http://www.boost.org/LICENSE_1_0.txt)
0008 //=======================================================================
0009 //
0010 #ifndef BOOST_GRAPH_MST_PRIM_HPP
0011 #define BOOST_GRAPH_MST_PRIM_HPP
0012
0013 #include <functional>
0014 #include <boost/graph/graph_traits.hpp>
0015 #include <boost/graph/dijkstra_shortest_paths.hpp>
0016
0017 namespace boost
0018 {
0019
0020 namespace detail
0021 {
0022     // this should be somewhere else in boost...
0023     template < class U, class V > struct _project2nd
0024     {
0025         V operator()(U, V v) const { return v; }
0026     };
0027 }
0028
0029 namespace detail
0030 {
0031
0032     // This is Prim's algorithm to calculate the Minimum Spanning Tree
0033     // for an undirected graph with weighted edges.
0034
0035     template < class Graph, class P, class T, class R, class Weight >
0036     inline void prim_mst_impl(const Graph& G,
0037         typename graph_traits< Graph >::vertex_descriptor s,
0038         const bgl_named_params< P, T, R >& params, Weight)
0039     {
0040         typedef typename property_traits< Weight >::value_type W;
0041         std::less< W > compare;
0042         detail::_project2nd< W, W > combine;
0043         dijkstra_shortest_paths(
0044             G, s, params.distance_compare(compare).distance_combine(combine));
0045     }
0046 } // namespace detail
0047
0048 template < class VertexListGraph, class DijkstraVisitor, class PredecessorMap,
0049     class DistanceMap, class WeightMap, class IndexMap >
0050 inline void prim_minimum_spanning_tree(const VertexListGraph& g,
0051     typename graph_traits< VertexListGraph >::vertex_descriptor s,
0052     PredecessorMap predecessor, DistanceMap distance, WeightMap weight,
0053     IndexMap index_map, DijkstraVisitor vis)
0054 {
0055     typedef typename property_traits< WeightMap >::value_type W;
0056     std::less< W > compare;
0057     detail::_project2nd< W, W > combine;
0058     dijkstra_shortest_paths(g, s, predecessor, distance, weight, index_map,
0059         compare, combine, (std::numeric_limits< W >::max)(), 0, vis);
0060 }
0061
0062 template < class VertexListGraph, class PredecessorMap, class P, class T,
0063     class R >
0064 inline void prim_minimum_spanning_tree(const VertexListGraph& g,
0065     PredecessorMap p_map, const bgl_named_params< P, T, R >& params)
0066 {
0067     detail::prim_mst_impl(g,
0068         choose_param(get_param(params, root_vertex_t()), *vertices(g).first),
0069         params.predecessor_map(p_map),
0070         choose_const_pmap(get_param(params, edge_weight), g, edge_weight));
0071 }
0072
0073 template < class VertexListGraph, class PredecessorMap >
0074 inline void prim_minimum_spanning_tree(
0075     const VertexListGraph& g, PredecessorMap p_map)
0076 {
0077     detail::prim_mst_impl(g, *vertices(g).first,
0078         predecessor_map(p_map).weight_map(get(edge_weight, g)),
0079         get(edge_weight, g));
0080 }
0081
0082 } // namespace boost
0083
0084 #endif // BOOST_GRAPH_MST_PRIM_HPP