*** depth_first_search.hpp.orig	Mon Aug 19 18:16:50 2002
--- depth_first_search.hpp	Sun Jun 22 15:17:30 2003
***************
*** 27,33 ****
  #ifndef BOOST_GRAPH_RECURSIVE_DFS_HPP
  #define BOOST_GRAPH_RECURSIVE_DFS_HPP
  
- #include <stack>
  #include <boost/config.hpp>
  #include <boost/graph/graph_traits.hpp>
  #include <boost/graph/graph_concepts.hpp>
--- 27,32 ----
***************
*** 35,40 ****
--- 34,40 ----
  #include <boost/graph/visitors.hpp>
  #include <boost/graph/named_function_params.hpp>
  #include <vector>
+ #include <utility>
  
  namespace boost {
  
***************
*** 61,66 ****
--- 61,138 ----
  
    namespace detail {
  
+ #ifdef BOOST_NONRECURSIVE_DFS
+ 
+     // Nonrecursive implementation of depth_first_visit_impl submitted by
+     // Bruce Barr, schmoost <at> yahoo.com, May/June 2003.
+ 
+     // If the vertex u and the iterators ei and ei_end are thought of as the
+     // context of the algorithm, each push and pop from the stack could
+     // be thought of as a context shift.
+     // Each pass through "while (ei != ei_end)" may refer to the out-edges of
+     // an entirely different vertex, because the context of the algorithm
+     // shifts every time a white adjacent vertex is discovered.
+     // The corresponding context shift back from the adjacent vertex occurs
+     // after all of its out-edges have been examined.
+ 
+     template <class IncidenceGraph, class DFSVisitor, class ColorMap>
+     void depth_first_visit_impl
+       (const IncidenceGraph& g,
+        typename graph_traits<IncidenceGraph>::vertex_descriptor u, 
+        DFSVisitor& vis,
+        ColorMap color)
+     {
+       function_requires<IncidenceGraphConcept<IncidenceGraph> >();
+       function_requires<DFSVisitorConcept<DFSVisitor, IncidenceGraph> >();
+       typedef typename graph_traits<IncidenceGraph>::vertex_descriptor Vertex;
+       function_requires< ReadWritePropertyMapConcept<ColorMap, Vertex> >();
+       typedef typename property_traits<ColorMap>::value_type ColorValue;
+       function_requires< ColorValueConcept<ColorValue> >();
+       typedef color_traits<ColorValue> Color;
+       typedef typename graph_traits<IncidenceGraph>::out_edge_iterator Iter;
+       typedef std::pair<Vertex, std::pair<Iter, Iter> > VertexInfo;
+ 
+       Iter ei, ei_end;
+       std::vector<VertexInfo> stack;
+ 
+       // Possible optimization for vector
+       //stack.reserve(num_vertices(g));
+ 
+       put(color, u, Color::gray());
+       vis.discover_vertex(u, g);
+       tie(ei, ei_end) = out_edges(u, g);
+       stack.push_back(std::make_pair(u, std::make_pair(ei, ei_end)));
+       while (!stack.empty()) {
+         VertexInfo& back = stack.back();
+         u = back.first;
+         tie(ei, ei_end) = back.second;
+         stack.pop_back();
+         while (ei != ei_end) {
+           Vertex v = target(*ei, g);
+           vis.examine_edge(*ei, g);
+           ColorValue v_color = get(color, v);
+           if (v_color == Color::white()) {
+             vis.tree_edge(*ei, g);
+             stack.push_back(std::make_pair(u, std::make_pair(++ei, ei_end)));
+             u = v;
+             put(color, u, Color::gray());
+             vis.discover_vertex(u, g);
+             tie(ei, ei_end) = out_edges(u, g);
+           } else if (v_color == Color::gray()) {
+             vis.back_edge(*ei, g);
+             ++ei;
+           } else {
+             vis.forward_or_cross_edge(*ei, g);
+             ++ei;
+           }
+         }
+         put(color, u, Color::black());
+         vis.finish_vertex(u, g);
+       }
+     }
+ 
+ #else // BOOST_NONRECURSIVE_DFS not defined
+ 
      template <class IncidenceGraph, class DFSVisitor, class ColorMap>
      void depth_first_visit_impl
        (const IncidenceGraph& g,
***************
*** 88,93 ****
--- 160,168 ----
        }
        put(color, u, Color::black());         vis.finish_vertex(u, g);
      }
+ 
+ #endif
+ 
    } // namespace detail
  
    template <class VertexListGraph, class DFSVisitor, class ColorMap,