1 //=======================================================================
2 // Copyright 2001 University of Notre Dame.
3 // Authors: Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee
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 <cstdio>
11 #include <cstring>
12 #include <iostream>
13 #include <boost/graph/stanford_graph.hpp>
14 #include <boost/graph/strong_components.hpp>
15
16 #define specs(v) (filename ? index_map[v] : v->cat_no) << " " << v->name
17
main(int argc,char * argv[])18 int main(int argc, char* argv[])
19 {
20 using namespace boost;
21 Graph* g;
22 typedef graph_traits< Graph* >::vertex_descriptor vertex_t;
23 unsigned long n = 0;
24 unsigned long d = 0;
25 unsigned long p = 0;
26 long s = 0;
27 char* filename = NULL;
28 int c, i;
29
30 while (--argc)
31 {
32 if (sscanf(argv[argc], "-n%lu", &n) == 1)
33 ;
34 else if (sscanf(argv[argc], "-d%lu", &d) == 1)
35 ;
36 else if (sscanf(argv[argc], "-p%lu", &p) == 1)
37 ;
38 else if (sscanf(argv[argc], "-s%ld", &s) == 1)
39 ;
40 else if (strncmp(argv[argc], "-g", 2) == 0)
41 filename = argv[argc] + 2;
42 else
43 {
44 fprintf(stderr, "Usage: %s [-nN][-dN][-pN][-sN][-gfoo]\n", argv[0]);
45 return -2;
46 }
47 }
48
49 g = (filename ? restore_graph(filename) : roget(n, d, p, s));
50 if (g == NULL)
51 {
52 fprintf(stderr, "Sorry, can't create the graph! (error code %ld)\n",
53 panic_code);
54 return -1;
55 }
56 printf("Reachability analysis of %s\n\n", g->id);
57
58 // - The root map corresponds to what Knuth calls the "min" field.
59 // - The discover time map is the "rank" field
60 // - Knuth uses the rank field for double duty, to record the
61 // discover time, and to keep track of which vertices have
62 // been visited. The BGL strong_components() function needs
63 // a separate field for marking colors, so we use the w field.
64
65 std::vector< int > comp(num_vertices(g));
66 property_map< Graph*, vertex_index_t >::type index_map
67 = get(vertex_index, g);
68
69 property_map< Graph*, v_property< vertex_t > >::type root
70 = get(v_property< vertex_t >(), g);
71
72 int num_comp = strong_components(g,
73 make_iterator_property_map(comp.begin(), index_map),
74 root_map(root)
75 .discover_time_map(get(z_property< long >(), g))
76 .color_map(get(w_property< long >(), g)));
77
78 std::vector< std::vector< vertex_t > > strong_comp(num_comp);
79
80 // First add representative vertices to each component's list
81 graph_traits< Graph* >::vertex_iterator vi, vi_end;
82 for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
83 if (root[*vi] == *vi)
84 strong_comp[comp[index_map[*vi]]].push_back(*vi);
85
86 // Then add the other vertices of the component
87 for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
88 if (root[*vi] != *vi)
89 strong_comp[comp[index_map[*vi]]].push_back(*vi);
90
91 // We do not print out the "from" and "to" information as Knuth
92 // does because we no longer have easy access to that information
93 // from outside the algorithm.
94
95 for (c = 0; c < num_comp; ++c)
96 {
97 vertex_t v = strong_comp[c].front();
98 std::cout << "Strong component `" << specs(v) << "'";
99 if (strong_comp[c].size() > 1)
100 {
101 std::cout << " also includes:\n";
102 for (i = 1; i < strong_comp[c].size(); ++i)
103 std::cout << " " << specs(strong_comp[c][i]) << std::endl;
104 }
105 else
106 std::cout << std::endl;
107 }
108
109 // Next we print out the "component graph" or "condensation", that
110 // is, we consider each component to be a vertex in a new graph
111 // where there is an edge connecting one component to another if there
112 // is one or more edges connecting any of the vertices from the
113 // first component to any of the vertices in the second. We use the
114 // name of the representative vertex as the name of the component.
115
116 printf("\nLinks between components:\n");
117
118 // This array provides an efficient way to check if we've already
119 // created a link from the current component to the component
120 // of the target vertex.
121 std::vector< int > mark(num_comp, (std::numeric_limits< int >::max)());
122
123 // We go in reverse order just to mimic the output ordering in
124 // Knuth's version.
125 for (c = num_comp - 1; c >= 0; --c)
126 {
127 vertex_t u = strong_comp[c][0];
128 for (i = 0; i < strong_comp[c].size(); ++i)
129 {
130 vertex_t v = strong_comp[c][i];
131 graph_traits< Graph* >::out_edge_iterator ei, ei_end;
132 for (boost::tie(ei, ei_end) = out_edges(v, g); ei != ei_end; ++ei)
133 {
134 vertex_t x = target(*ei, g);
135 int comp_x = comp[index_map[x]];
136 if (comp_x != c && mark[comp_x] != c)
137 {
138 mark[comp_x] = c;
139 vertex_t w = strong_comp[comp_x][0];
140 std::cout << specs(u) << " -> " << specs(w) << " (e.g., "
141 << specs(v) << " -> " << specs(x) << ")\n";
142 } // if
143 } // for
144 } // for
145 } // for
146 }
147