ceph/src/boost/libs/graph/include/boost/graph/lookup_edge.hpp

   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