78 lines
2.6 KiB
C++
78 lines
2.6 KiB
C++
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//
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//=======================================================================
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// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
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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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//
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#ifndef BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
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#define BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
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#include <boost/config.hpp>
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#include <boost/property_map/property_map.hpp>
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#include <boost/graph/depth_first_search.hpp>
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#include <boost/graph/visitors.hpp>
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#include <boost/graph/exception.hpp>
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#include <boost/throw_exception.hpp>
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namespace boost {
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// Topological sort visitor
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//
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// This visitor merely writes the linear ordering into an
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// OutputIterator. The OutputIterator could be something like an
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// ostream_iterator, or it could be a back/front_insert_iterator.
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// Note that if it is a back_insert_iterator, the recorded order is
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// the reverse topological order. On the other hand, if it is a
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// front_insert_iterator, the recorded order is the topological
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// order.
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//
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template <typename OutputIterator>
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struct topo_sort_visitor : public dfs_visitor<>
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{
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topo_sort_visitor(OutputIterator _iter)
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: m_iter(_iter) { }
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template <typename Edge, typename Graph>
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void back_edge(const Edge&, Graph&) { BOOST_THROW_EXCEPTION(not_a_dag()); }
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template <typename Vertex, typename Graph>
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void finish_vertex(const Vertex& u, Graph&) { *m_iter++ = u; }
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OutputIterator m_iter;
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};
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// Topological Sort
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//
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// The topological sort algorithm creates a linear ordering
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// of the vertices such that if edge (u,v) appears in the graph,
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// then u comes before v in the ordering. The graph must
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// be a directed acyclic graph (DAG). The implementation
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// consists mainly of a call to depth-first search.
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//
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template <typename VertexListGraph, typename OutputIterator,
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typename P, typename T, typename R>
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void topological_sort(VertexListGraph& g, OutputIterator result,
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const bgl_named_params<P, T, R>& params)
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{
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typedef topo_sort_visitor<OutputIterator> TopoVisitor;
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depth_first_search(g, params.visitor(TopoVisitor(result)));
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}
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template <typename VertexListGraph, typename OutputIterator>
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void topological_sort(VertexListGraph& g, OutputIterator result)
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{
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topological_sort(g, result,
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bgl_named_params<int, buffer_param_t>(0)); // bogus
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}
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} // namespace boost
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#endif /*BOOST_GRAPH_TOPOLOGICAL_SORT_H*/
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