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- //=======================================================================
- // Copyright 2009 Trustees of Indiana University
- // Author: Jeremiah Willcock
- //
- // Distributed under the Boost Software License, Version 1.0. (See
- // accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //=======================================================================
- #ifndef BOOST_GRAPH_LOOKUP_EDGE_HPP
- #define BOOST_GRAPH_LOOKUP_EDGE_HPP
- #include <utility>
- #include <boost/config.hpp>
- #include <boost/utility/enable_if.hpp>
- #include <boost/graph/graph_traits.hpp>
- // lookup_edge: a function that acts like edge() but falls back to out_edges()
- // and a search when edge() is not provided.
- namespace boost {
- template <typename Graph>
- std::pair<typename boost::graph_traits<Graph>::edge_descriptor, bool>
- lookup_edge(typename boost::graph_traits<Graph>::vertex_descriptor src,
- typename boost::graph_traits<Graph>::vertex_descriptor tgt,
- const Graph& g,
- typename boost::enable_if<is_adjacency_matrix<Graph>, int>::type = 0) {
- return edge(src, tgt, g);
- }
- template <typename Graph>
- std::pair<typename boost::graph_traits<Graph>::edge_descriptor, bool>
- lookup_edge(typename boost::graph_traits<Graph>::vertex_descriptor src,
- typename boost::graph_traits<Graph>::vertex_descriptor tgt,
- const Graph& g,
- typename boost::disable_if<is_adjacency_matrix<Graph>, int>::type = 0) {
- typedef typename boost::graph_traits<Graph>::out_edge_iterator it;
- typedef typename boost::graph_traits<Graph>::edge_descriptor edesc;
- std::pair<it, it> oe = out_edges(src, g);
- for (; oe.first != oe.second; ++oe.first) {
- edesc e = *oe.first;
- if (target(e, g) == tgt) return std::make_pair(e, true);
- }
- return std::make_pair(edesc(), false);
- }
- }
- #endif // BOOST_GRAPH_LOOKUP_EDGE_HPP
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