1 //=======================================================================
2 // Copyright 2009 Trustees of Indiana University
3 // Author: Jeremiah Willcock
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 //=======================================================================
10 #ifndef BOOST_GRAPH_LOOKUP_EDGE_HPP
11 #define BOOST_GRAPH_LOOKUP_EDGE_HPP
14 #include <boost/config.hpp>
15 #include <boost/utility/enable_if.hpp>
16 #include <boost/graph/graph_traits.hpp>
18 // lookup_edge: a function that acts like edge() but falls back to out_edges()
19 // and a search when edge() is not provided.
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,
28 typename boost::enable_if<is_adjacency_matrix<Graph>, int>::type = 0) {
29 return edge(src, tgt, g);
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,
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) {
43 if (target(e, g) == tgt) return std::make_pair(e, true);
45 return std::make_pair(edesc(), false);
50 #endif // BOOST_GRAPH_LOOKUP_EDGE_HPP