Chris@16: //
Chris@16: //=======================================================================
Chris@16: // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
Chris@16: // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //=======================================================================
Chris@16: //
Chris@16: #ifndef BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
Chris@16: #define BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
Chris@16: 
Chris@16: #include <boost/config.hpp>
Chris@16: #include <boost/property_map/property_map.hpp>
Chris@16: #include <boost/graph/depth_first_search.hpp>
Chris@16: #include <boost/graph/visitors.hpp>
Chris@16: #include <boost/graph/exception.hpp>
Chris@16: #include <boost/throw_exception.hpp>
Chris@16: 
Chris@16: namespace boost { 
Chris@16: 
Chris@16: 
Chris@16:   // Topological sort visitor
Chris@16:   //
Chris@16:   // This visitor merely writes the linear ordering into an
Chris@16:   // OutputIterator. The OutputIterator could be something like an
Chris@16:   // ostream_iterator, or it could be a back/front_insert_iterator.
Chris@16:   // Note that if it is a back_insert_iterator, the recorded order is
Chris@16:   // the reverse topological order. On the other hand, if it is a
Chris@16:   // front_insert_iterator, the recorded order is the topological
Chris@16:   // order.
Chris@16:   //
Chris@16:   template <typename OutputIterator>
Chris@16:   struct topo_sort_visitor : public dfs_visitor<>
Chris@16:   {
Chris@16:     topo_sort_visitor(OutputIterator _iter)
Chris@16:       : m_iter(_iter) { }
Chris@16:     
Chris@16:     template <typename Edge, typename Graph>
Chris@16:     void back_edge(const Edge&, Graph&) { BOOST_THROW_EXCEPTION(not_a_dag()); }
Chris@16:     
Chris@16:     template <typename Vertex, typename Graph> 
Chris@16:     void finish_vertex(const Vertex& u, Graph&) { *m_iter++ = u; }
Chris@16:     
Chris@16:     OutputIterator m_iter;
Chris@16:   };
Chris@16: 
Chris@16: 
Chris@16:   // Topological Sort
Chris@16:   //
Chris@16:   // The topological sort algorithm creates a linear ordering
Chris@16:   // of the vertices such that if edge (u,v) appears in the graph,
Chris@16:   // then u comes before v in the ordering. The graph must
Chris@16:   // be a directed acyclic graph (DAG). The implementation
Chris@16:   // consists mainly of a call to depth-first search.
Chris@16:   //
Chris@16: 
Chris@16:   template <typename VertexListGraph, typename OutputIterator,
Chris@16:     typename P, typename T, typename R>
Chris@16:   void topological_sort(VertexListGraph& g, OutputIterator result,
Chris@16:                         const bgl_named_params<P, T, R>& params)
Chris@16:   {
Chris@16:     typedef topo_sort_visitor<OutputIterator> TopoVisitor;
Chris@16:     depth_first_search(g, params.visitor(TopoVisitor(result)));
Chris@16:   }
Chris@16: 
Chris@16:   template <typename VertexListGraph, typename OutputIterator>
Chris@16:   void topological_sort(VertexListGraph& g, OutputIterator result)
Chris@16:   {
Chris@16:     topological_sort(g, result, 
Chris@16:                      bgl_named_params<int, buffer_param_t>(0)); // bogus
Chris@16:   }
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif /*BOOST_GRAPH_TOPOLOGICAL_SORT_H*/