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50 lines
1.9 KiB
50 lines
1.9 KiB
//======================================================================= |
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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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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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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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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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edesc e = *oe.first; |
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if (target(e, g) == tgt) 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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