1 //=======================================================================
2 // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
3 // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
4 //
5 // Distributed under the Boost Software License, Version 1.0. (See
6 // accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8 //=======================================================================
9
10 #include <boost/config.hpp>
11
12 #include <algorithm>
13 #include <vector>
14 #include <utility>
15 #include <iostream>
16
17 #include <boost/graph/graph_utility.hpp>
18 #include <boost/graph/visitors.hpp>
19 #include <boost/graph/adjacency_list.hpp>
20 #include <boost/graph/neighbor_bfs.hpp>
21 #include <boost/property_map/property_map.hpp>
22
23 /*
24
25 This examples shows how to use the breadth_first_search() GGCL
26 algorithm, specifically the 3 argument variant of bfs that assumes
27 the graph has a color property (property) stored internally.
28
29 Two pre-defined visitors are used to record the distance of each
30 vertex from the source vertex, and also to record the parent of each
31 vertex. Any number of visitors can be layered and passed to a GGCL
32 algorithm.
33
34 The call to vertices(G) returns an STL-compatible container which
35 contains all of the vertices in the graph. In this example we use
36 the vertices container in the STL for_each() function.
37
38 Sample Output:
39
40 0 --> 2
41 1 --> 1 3 4
42 2 --> 1 3 4
43 3 --> 1 4
44 4 --> 0 1
45 distances: 1 2 1 2 0
46 parent[0] = 4
47 parent[1] = 2
48 parent[2] = 0
49 parent[3] = 2
50 parent[4] = 0
51
52 */
53
54 template < class ParentDecorator > struct print_parent
55 {
print_parentprint_parent56 print_parent(const ParentDecorator& p_) : p(p_) {}
operator ()print_parent57 template < class Vertex > void operator()(const Vertex& v) const
58 {
59 std::cout << "parent[" << v << "] = " << p[v] << std::endl;
60 }
61 ParentDecorator p;
62 };
63
64 template < class NewGraph, class Tag >
65 struct graph_copier
66 : public boost::base_visitor< graph_copier< NewGraph, Tag > >
67 {
68 typedef Tag event_filter;
69
graph_copiergraph_copier70 graph_copier(NewGraph& graph) : new_g(graph) {}
71
operator ()graph_copier72 template < class Edge, class Graph > void operator()(Edge e, Graph& g)
73 {
74 boost::add_edge(boost::source(e, g), boost::target(e, g), new_g);
75 }
76
77 private:
78 NewGraph& new_g;
79 };
80
81 template < class NewGraph, class Tag >
copy_graph(NewGraph & g,Tag)82 inline graph_copier< NewGraph, Tag > copy_graph(NewGraph& g, Tag)
83 {
84 return graph_copier< NewGraph, Tag >(g);
85 }
86
main(int,char * [])87 int main(int, char*[])
88 {
89 typedef boost::adjacency_list< boost::mapS, boost::vecS,
90 boost::bidirectionalS,
91 boost::property< boost::vertex_color_t, boost::default_color_type,
92 boost::property< boost::vertex_degree_t, int,
93 boost::property< boost::vertex_in_degree_t, int,
94 boost::property< boost::vertex_out_degree_t, int > > > > >
95 Graph;
96
97 Graph G(5);
98 boost::add_edge(0, 2, G);
99 boost::add_edge(1, 1, G);
100 boost::add_edge(1, 3, G);
101 boost::add_edge(1, 4, G);
102 boost::add_edge(2, 1, G);
103 boost::add_edge(2, 3, G);
104 boost::add_edge(2, 4, G);
105 boost::add_edge(3, 1, G);
106 boost::add_edge(3, 4, G);
107 boost::add_edge(4, 0, G);
108 boost::add_edge(4, 1, G);
109
110 typedef Graph::vertex_descriptor Vertex;
111
112 // Array to store predecessor (parent) of each vertex. This will be
113 // used as a Decorator (actually, its iterator will be).
114 std::vector< Vertex > p(boost::num_vertices(G));
115 // VC++ version of std::vector has no ::pointer, so
116 // I use ::value_type* instead.
117 typedef std::vector< Vertex >::value_type* Piter;
118
119 // Array to store distances from the source to each vertex . We use
120 // a built-in array here just for variety. This will also be used as
121 // a Decorator.
122 boost::graph_traits< Graph >::vertices_size_type d[5];
123 std::fill_n(d, 5, 0);
124
125 // The source vertex
126 Vertex s = *(boost::vertices(G).first);
127 p[s] = s;
128 boost::neighbor_breadth_first_search(G, s,
129 boost::visitor(boost::make_neighbor_bfs_visitor(
130 std::make_pair(boost::record_distances(d, boost::on_tree_edge()),
131 boost::record_predecessors(&p[0], boost::on_tree_edge())))));
132
133 boost::print_graph(G);
134
135 if (boost::num_vertices(G) < 11)
136 {
137 std::cout << "distances: ";
138 #ifdef BOOST_OLD_STREAM_ITERATORS
139 std::copy(d, d + 5, std::ostream_iterator< int, char >(std::cout, " "));
140 #else
141 std::copy(d, d + 5, std::ostream_iterator< int >(std::cout, " "));
142 #endif
143 std::cout << std::endl;
144
145 std::for_each(boost::vertices(G).first, boost::vertices(G).second,
146 print_parent< Piter >(&p[0]));
147 }
148
149 return 0;
150 }
151