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