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1 | //======================================================================= |
2 | // Copyright 2009 Trustees of Indiana University | |
3 | // Author: Jeremiah Willcock | |
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 | #ifndef BOOST_GRAPH_LOOKUP_EDGE_HPP | |
11 | #define BOOST_GRAPH_LOOKUP_EDGE_HPP | |
12 | ||
13 | #include <utility> | |
14 | #include <boost/config.hpp> | |
15 | #include <boost/utility/enable_if.hpp> | |
16 | #include <boost/graph/graph_traits.hpp> | |
17 | ||
18 | // lookup_edge: a function that acts like edge() but falls back to out_edges() | |
19 | // and a search when edge() is not provided. | |
20 | ||
21 | namespace boost { | |
22 | ||
23 | template <typename Graph> | |
24 | std::pair<typename boost::graph_traits<Graph>::edge_descriptor, bool> | |
25 | lookup_edge(typename boost::graph_traits<Graph>::vertex_descriptor src, | |
26 | typename boost::graph_traits<Graph>::vertex_descriptor tgt, | |
27 | const Graph& g, | |
28 | typename boost::enable_if<is_adjacency_matrix<Graph>, int>::type = 0) { | |
29 | return edge(src, tgt, g); | |
30 | } | |
31 | ||
32 | template <typename Graph> | |
33 | std::pair<typename boost::graph_traits<Graph>::edge_descriptor, bool> | |
34 | lookup_edge(typename boost::graph_traits<Graph>::vertex_descriptor src, | |
35 | typename boost::graph_traits<Graph>::vertex_descriptor tgt, | |
36 | const Graph& g, | |
37 | typename boost::disable_if<is_adjacency_matrix<Graph>, int>::type = 0) { | |
38 | typedef typename boost::graph_traits<Graph>::out_edge_iterator it; | |
39 | typedef typename boost::graph_traits<Graph>::edge_descriptor edesc; | |
40 | std::pair<it, it> oe = out_edges(src, g); | |
41 | for (; oe.first != oe.second; ++oe.first) { | |
42 | edesc e = *oe.first; | |
43 | if (target(e, g) == tgt) return std::make_pair(e, true); | |
44 | } | |
45 | return std::make_pair(edesc(), false); | |
46 | } | |
47 | ||
48 | } | |
49 | ||
50 | #endif // BOOST_GRAPH_LOOKUP_EDGE_HPP |