source: NonGTP/Boost/boost/graph/topological_sort.hpp @ 857

Revision 857, 2.6 KB checked in by igarcia, 19 years ago (diff)
Line 
1//
2//=======================================================================
3// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
4// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
5//
6// Distributed under the Boost Software License, Version 1.0. (See
7// accompanying file LICENSE_1_0.txt or copy at
8// http://www.boost.org/LICENSE_1_0.txt)
9//=======================================================================
10//
11#ifndef BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
12#define BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
13
14#include <boost/config.hpp>
15#include <boost/property_map.hpp>
16#include <boost/graph/depth_first_search.hpp>
17#include <boost/graph/visitors.hpp>
18#include <boost/graph/exception.hpp>
19
20namespace boost {
21
22
23  // Topological sort visitor
24  //
25  // This visitor merely writes the linear ordering into an
26  // OutputIterator. The OutputIterator could be something like an
27  // ostream_iterator, or it could be a back/front_insert_iterator.
28  // Note that if it is a back_insert_iterator, the recorded order is
29  // the reverse topological order. On the other hand, if it is a
30  // front_insert_iterator, the recorded order is the topological
31  // order.
32  //
33  template <typename OutputIterator>
34  struct topo_sort_visitor : public dfs_visitor<>
35  {
36    topo_sort_visitor(OutputIterator _iter)
37      : m_iter(_iter) { }
38   
39    template <typename Edge, typename Graph>
40    void back_edge(const Edge& u, Graph&) { throw not_a_dag(); }
41   
42    template <typename Vertex, typename Graph>
43    void finish_vertex(const Vertex& u, Graph&) { *m_iter++ = u; }
44   
45    OutputIterator m_iter;
46  };
47
48
49  // Topological Sort
50  //
51  // The topological sort algorithm creates a linear ordering
52  // of the vertices such that if edge (u,v) appears in the graph,
53  // then u comes before v in the ordering. The graph must
54  // be a directed acyclic graph (DAG). The implementation
55  // consists mainly of a call to depth-first search.
56  //
57
58  template <typename VertexListGraph, typename OutputIterator,
59    typename P, typename T, typename R>
60  void topological_sort(VertexListGraph& g, OutputIterator result,
61                        const bgl_named_params<P, T, R>& params)
62  {
63    typedef topo_sort_visitor<OutputIterator> TopoVisitor;
64    depth_first_search(g, params.visitor(TopoVisitor(result)));
65  }
66
67  template <typename VertexListGraph, typename OutputIterator>
68  void topological_sort(VertexListGraph& g, OutputIterator result)
69  {
70    topological_sort(g, result,
71                     bgl_named_params<int, buffer_param_t>(0)); // bogus
72  }
73
74} // namespace boost
75
76#endif /*BOOST_GRAPH_TOPOLOGICAL_SORT_H*/
Note: See TracBrowser for help on using the repository browser.