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3rdparty/boost_1_81_0/boost/graph/lookup_edge.hpp 1.85 KB
63e88f80   Hu Chunming   提交三方库
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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