| //======================================================================= |
| // 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 |