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/visitors.hpp>
18 #include <boost/graph/adjacency_list.hpp>
19 #include <boost/graph/breadth_first_search.hpp>
20 #include <boost/property_map/property_map.hpp>
21 #include <boost/graph/graph_utility.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 0 --> 2
46 1 --> 1 3 4
47 2 --> 1 3 4
48 3 --> 1 4
49 4 --> 0 1
50 distances: 0 2 1 2 2
51 parent[0] = 0
52 parent[1] = 2
53 parent[2] = 0
54 parent[3] = 2
55 parent[4] = 2
56
57 */
58
59 template < class ParentDecorator > struct print_parent
60 {
print_parentprint_parent61 print_parent(const ParentDecorator& p_) : p(p_) {}
operator ()print_parent62 template < class Vertex > void operator()(const Vertex& v) const
63 {
64 std::cout << "parent[" << v << "] = " << p[v] << std::endl;
65 }
66 ParentDecorator p;
67 };
68
69 template < class NewGraph, class Tag >
70 struct graph_copier
71 : public boost::base_visitor< graph_copier< NewGraph, Tag > >
72 {
73 typedef Tag event_filter;
74
graph_copiergraph_copier75 graph_copier(NewGraph& graph) : new_g(graph) {}
76
operator ()graph_copier77 template < class Edge, class Graph > void operator()(Edge e, Graph& g)
78 {
79 boost::add_edge(boost::source(e, g), boost::target(e, g), new_g);
80 }
81
82 private:
83 NewGraph& new_g;
84 };
85
86 template < class NewGraph, class Tag >
copy_graph(NewGraph & g,Tag)87 inline graph_copier< NewGraph, Tag > copy_graph(NewGraph& g, Tag)
88 {
89 return graph_copier< NewGraph, Tag >(g);
90 }
91
main(int,char * [])92 int main(int, char*[])
93 {
94 typedef boost::adjacency_list< boost::mapS, boost::vecS,
95 boost::bidirectionalS,
96 boost::property< boost::vertex_color_t, boost::default_color_type,
97 boost::property< boost::vertex_degree_t, int,
98 boost::property< boost::vertex_in_degree_t, int,
99 boost::property< boost::vertex_out_degree_t, int > > > > >
100 Graph;
101
102 Graph G(5);
103 boost::add_edge(0, 2, G);
104 boost::add_edge(1, 1, G);
105 boost::add_edge(1, 3, G);
106 boost::add_edge(1, 4, G);
107 boost::add_edge(2, 1, G);
108 boost::add_edge(2, 3, G);
109 boost::add_edge(2, 4, G);
110 boost::add_edge(3, 1, G);
111 boost::add_edge(3, 4, G);
112 boost::add_edge(4, 0, G);
113 boost::add_edge(4, 1, G);
114
115 typedef Graph::vertex_descriptor Vertex;
116
117 Graph G_copy(5);
118 // Array to store predecessor (parent) of each vertex. This will be
119 // used as a Decorator (actually, its iterator will be).
120 std::vector< Vertex > p(boost::num_vertices(G));
121 // VC++ version of std::vector has no ::pointer, so
122 // I use ::value_type* instead.
123 typedef std::vector< Vertex >::value_type* Piter;
124
125 // Array to store distances from the source to each vertex . We use
126 // a built-in array here just for variety. This will also be used as
127 // a Decorator.
128 boost::graph_traits< Graph >::vertices_size_type d[5];
129 std::fill_n(d, 5, 0);
130
131 // The source vertex
132 Vertex s = *(boost::vertices(G).first);
133 p[s] = s;
134 boost::breadth_first_search(G, s,
135 boost::visitor(boost::make_bfs_visitor(
136 std::make_pair(boost::record_distances(d, boost::on_tree_edge()),
137 std::make_pair(
138 boost::record_predecessors(&p[0], boost::on_tree_edge()),
139 copy_graph(G_copy, boost::on_examine_edge()))))));
140
141 boost::print_graph(G);
142 boost::print_graph(G_copy);
143
144 if (boost::num_vertices(G) < 11)
145 {
146 std::cout << "distances: ";
147 #ifdef BOOST_OLD_STREAM_ITERATORS
148 std::copy(d, d + 5, std::ostream_iterator< int, char >(std::cout, " "));
149 #else
150 std::copy(d, d + 5, std::ostream_iterator< int >(std::cout, " "));
151 #endif
152 std::cout << std::endl;
153
154 std::for_each(boost::vertices(G).first, boost::vertices(G).second,
155 print_parent< Piter >(&p[0]));
156 }
157
158 return 0;
159 }
160