williamr@2: //
williamr@2: //=======================================================================
williamr@2: // Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
williamr@2: // Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. (See
williamr@2: // accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //=======================================================================
williamr@2: //
williamr@2: #ifndef BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
williamr@2: #define BOOST_GRAPH_TOPOLOGICAL_SORT_HPP
williamr@2: 
williamr@2: #include <boost/config.hpp>
williamr@2: #include <boost/property_map.hpp>
williamr@2: #include <boost/graph/depth_first_search.hpp>
williamr@2: #include <boost/graph/visitors.hpp>
williamr@2: #include <boost/graph/exception.hpp>
williamr@2: 
williamr@2: namespace boost { 
williamr@2: 
williamr@2: 
williamr@2:   // Topological sort visitor
williamr@2:   //
williamr@2:   // This visitor merely writes the linear ordering into an
williamr@2:   // OutputIterator. The OutputIterator could be something like an
williamr@2:   // ostream_iterator, or it could be a back/front_insert_iterator.
williamr@2:   // Note that if it is a back_insert_iterator, the recorded order is
williamr@2:   // the reverse topological order. On the other hand, if it is a
williamr@2:   // front_insert_iterator, the recorded order is the topological
williamr@2:   // order.
williamr@2:   //
williamr@2:   template <typename OutputIterator>
williamr@2:   struct topo_sort_visitor : public dfs_visitor<>
williamr@2:   {
williamr@2:     topo_sort_visitor(OutputIterator _iter)
williamr@2:       : m_iter(_iter) { }
williamr@2:     
williamr@2:     template <typename Edge, typename Graph>
williamr@2:     void back_edge(const Edge& u, Graph&) { throw not_a_dag(); }
williamr@2:     
williamr@2:     template <typename Vertex, typename Graph> 
williamr@2:     void finish_vertex(const Vertex& u, Graph&) { *m_iter++ = u; }
williamr@2:     
williamr@2:     OutputIterator m_iter;
williamr@2:   };
williamr@2: 
williamr@2: 
williamr@2:   // Topological Sort
williamr@2:   //
williamr@2:   // The topological sort algorithm creates a linear ordering
williamr@2:   // of the vertices such that if edge (u,v) appears in the graph,
williamr@2:   // then u comes before v in the ordering. The graph must
williamr@2:   // be a directed acyclic graph (DAG). The implementation
williamr@2:   // consists mainly of a call to depth-first search.
williamr@2:   //
williamr@2: 
williamr@2:   template <typename VertexListGraph, typename OutputIterator,
williamr@2:     typename P, typename T, typename R>
williamr@2:   void topological_sort(VertexListGraph& g, OutputIterator result,
williamr@2:                         const bgl_named_params<P, T, R>& params)
williamr@2:   {
williamr@2:     typedef topo_sort_visitor<OutputIterator> TopoVisitor;
williamr@2:     depth_first_search(g, params.visitor(TopoVisitor(result)));
williamr@2:   }
williamr@2: 
williamr@2:   template <typename VertexListGraph, typename OutputIterator>
williamr@2:   void topological_sort(VertexListGraph& g, OutputIterator result)
williamr@2:   {
williamr@2:     topological_sort(g, result, 
williamr@2:                      bgl_named_params<int, buffer_param_t>(0)); // bogus
williamr@2:   }
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif /*BOOST_GRAPH_TOPOLOGICAL_SORT_H*/