1 //=======================================================================
2 // Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See
5 // accompanying file LICENSE_1_0.txt or copy at
6 // http://www.boost.org/LICENSE_1_0.txt)
7 //=======================================================================
8 #include <boost/graph/graph_traits.hpp>
9 #include <boost/graph/adjacency_list.hpp>
10
11 using namespace boost;
12
13 template < typename Graph > void
generic_foo(Graph & g)14 generic_foo(Graph & g)
15 {
16 // Access descriptor types
17 typedef typename graph_traits < Graph >::vertex_descriptor Vertex;
18 typedef typename graph_traits < Graph >::edge_descriptor Edge;
19 // Access category types
20 typedef typename graph_traits < Graph >::directed_category Dir;
21 typedef typename graph_traits < Graph >::edge_parallel_category Par;
22 // Access iterator types...
23 // Access size types...
24 // Now do something useful...
25 }
26
27 template < typename Graph > void
generic_bar(Graph & g)28 generic_bar(Graph & g)
29 {
30 // Declare some vertex and edge descriptor variables
31 typename graph_traits < Graph >::vertex_descriptor u, v;
32 typename graph_traits < Graph >::edge_descriptor e1, e2;
33 // Set u and e1 to valid descriptors...
34 v = u; // Make v a handle to the same vertex as u.
35 e2 = e1; // Make e2 a handle to the same edge as e1.
36 assert(u == v); // Do u and v identify the same vertex? Yes
37 assert(!(u != v)); // Do u and v identify different vertices? No
38 assert(e1 == e2); // Do e1 and e2 identify the same edge? Yes
39 assert(!(e1 != e2)); // Do e1 and e2 identify different edges? No
40 }
41
42 // This version of foo gets called when g is directed
43 template < typename Graph > void
foo_dispatch(Graph & g,boost::directed_tag)44 foo_dispatch(Graph & g, boost::directed_tag)
45 {
46 //...
47 }
48
49 // This version of foo gets called when g is undirected
50 template < typename Graph > void
foo_dispatch(Graph & g,boost::undirected_tag)51 foo_dispatch(Graph & g, boost::undirected_tag)
52 {
53 //...
54 }
55
56 template < typename Graph > void
foo(Graph & g)57 foo(Graph & g)
58 {
59 typedef typename boost::graph_traits < Graph >::directed_category Cat;
60 foo_dispatch(g, Cat());
61 }
62
63 template < typename Digraph > void
foo(Digraph & digraph,typename graph_traits<Digraph>::vertex_descriptor u,typename graph_traits<Digraph>::vertex_descriptor v)64 foo(Digraph & digraph,
65 typename graph_traits < Digraph >::vertex_descriptor u,
66 typename graph_traits < Digraph >::vertex_descriptor v)
67 {
68 typedef typename graph_traits < Digraph >::edge_descriptor edge_t;
69 std::pair<edge_t, bool> e1, e2;
70 e1 = edge(u, v, digraph);
71 e2 = edge(v, u, digraph);
72 assert(e1.first != e2.first);
73 }
74 template < typename Undigraph > void
bar(Undigraph & undigraph,typename graph_traits<Undigraph>::vertex_descriptor u,typename graph_traits<Undigraph>::vertex_descriptor v)75 bar(Undigraph & undigraph,
76 typename graph_traits < Undigraph >::vertex_descriptor u,
77 typename graph_traits < Undigraph >::vertex_descriptor v)
78 {
79 typedef typename graph_traits < Undigraph >::edge_descriptor edge_t;
80 std::pair<edge_t, bool> e1, e2;
81 e1 = edge(u, v, undigraph);
82 e2 = edge(v, u, undigraph);
83 assert(e1.first == e2.first);
84 }
85
86
87 int
main()88 main()
89 {
90
91 boost::adjacency_list < vecS, vecS, directedS > g(2);
92 add_edge(0, 1, g);
93 add_edge(1, 0, g);
94 generic_foo(g);
95 generic_bar(g);
96 foo(g);
97 foo(g, vertex(0, g), vertex(1, g));
98
99 boost::adjacency_list < vecS, vecS, undirectedS > ug(2);
100 add_edge(0, 1, g);
101 bar(ug, vertex(0, g), vertex(1, g));
102
103 return 0;
104 }
105