Ticket #5269: dfs-on_finish_edge.diff

boost/graph/depth_first_search.hpp

@@ -39 +39 @@
       vis.tree_edge(e, g);
       vis.back_edge(e, g);
       vis.forward_or_cross_edge(e, g);
+      vis.finish_edge(e, g);
       vis.finish_vertex(u, g);
     }
   private:
@@ -77 +78 @@
     void depth_first_visit_impl
       (const IncidenceGraph& g,
        typename graph_traits<IncidenceGraph>::vertex_descriptor u,
-       DFSVisitor& vis,
+       DFSVisitor& vis,  // pass-by-reference here, important!
        ColorMap color, TerminatorFunc func = TerminatorFunc())
     {
       function_requires<IncidenceGraphConcept<IncidenceGraph> >();
@@ -88 +89 @@
       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;
+      typedef std::pair<Iter, Iter> VertexInfo;
 
       Iter ei, ei_end;
       std::vector<VertexInfo> stack;
@@ -98 +99 @@
 
       typedef typename unwrap_reference<TerminatorFunc>::type TF;
 
-      put(color, u, Color::gray());
-      vis.discover_vertex(u, g);
-      boost::tie(ei, ei_end) = out_edges(u, g);
+      put(color, u, Color::gray());                  vis.discover_vertex(u, g);
       // Variable is needed to workaround a borland bug.
       TF& fn = static_cast<TF&>(func);
       if (fn(u, g)) {
-          // If this vertex terminates the search, we push empty range
-          stack.push_back(std::make_pair(u, std::make_pair(ei_end, ei_end)));
-      } else {
-          stack.push_back(std::make_pair(u, std::make_pair(ei, ei_end)));
+        put(color, u, Color::black());               vis.finish_vertex(u, g);
+        return;
       }
-      while (!stack.empty()) {
-        VertexInfo& back = stack.back();
-        u = back.first;
-        boost::tie(ei, ei_end) = back.second;
-        stack.pop_back();
-        while (ei != ei_end) {
+
+      for (tie(ei, ei_end) = out_edges(u, g); ; ++ei) {
+        while (ei != ei_end) {                       vis.examine_edge(*ei, g);
           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)));
+          if (v_color == Color::white()) {           vis.tree_edge(*ei, g);
+            stack.push_back(VertexInfo(ei, ei_end));
             u = v;
-            put(color, u, Color::gray());
-            vis.discover_vertex(u, g);
-            boost::tie(ei, ei_end) = out_edges(u, g);
+            put(color, u, Color::gray());            vis.discover_vertex(u, g);
             if (fn(u, g)) {
-                ei = ei_end;
+              ei = ei_end;
+            } else {
+              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);
+            if (v_color == Color::gray())            vis.back_edge(*ei, g);
+            else                             vis.forward_or_cross_edge(*ei, g);
+                                                     vis.finish_edge(*ei, g);
             ++ei;
           }
         }
-        put(color, u, Color::black());
-        vis.finish_vertex(u, g);
+        put(color, u, Color::black());               vis.finish_vertex(u, g);
+        if (stack.empty()) break;
+        tie(ei, ei_end) = stack.back();
+        u = source(*ei, g);
+        stack.pop_back();                            vis.finish_edge(*ei, g);
       }
     }
 
@@ -173 +167 @@
           depth_first_visit_impl(g, v, vis, color, func);
           } else if (v_color == Color::gray()) vis.back_edge(*ei, g);
           else                                 vis.forward_or_cross_edge(*ei, g);
+                                               vis.finish_edge(*ei, g);
         }
       put(color, u, Color::black());         vis.finish_vertex(u, g);
     }
@@ -257 +252 @@
     void forward_or_cross_edge(Edge u, const Graph& g) {
       invoke_visitors(m_vis, u, g, ::boost::on_forward_or_cross_edge());
     }
+    template <class Edge, class Graph>
+    void finish_edge(Edge u, const Graph& g) {
+      invoke_visitors(m_vis, u, g, ::boost::on_finish_edge());
+    }
     template <class Vertex, class Graph>
     void finish_vertex(Vertex u, const Graph& g) {
       invoke_visitors(m_vis, u, g, ::boost::on_finish_vertex());
@@ -269 +268 @@
     BOOST_GRAPH_EVENT_STUB(on_tree_edge,dfs)
     BOOST_GRAPH_EVENT_STUB(on_back_edge,dfs)
     BOOST_GRAPH_EVENT_STUB(on_forward_or_cross_edge,dfs)
+    BOOST_GRAPH_EVENT_STUB(on_finish_edge,dfs)
     BOOST_GRAPH_EVENT_STUB(on_finish_vertex,dfs)
 
   protected:

boost/graph/undirected_dfs.hpp

@@ -28 +28 @@
     void undir_dfv_impl
       (const IncidenceGraph& g,
        typename graph_traits<IncidenceGraph>::vertex_descriptor u, 
-       DFSVisitor& vis,
+       DFSVisitor& vis,  // pass-by-reference here, important!
        VertexColorMap vertex_color,
        EdgeColorMap edge_color)
     {
@@ -45 +45 @@
       typedef color_traits<ColorValue> Color;
       typedef color_traits<EColorValue> EColor;
       typedef typename graph_traits<IncidenceGraph>::out_edge_iterator Iter;
-      typedef std::pair<Vertex, std::pair<Iter, Iter> > VertexInfo;
+      typedef std::pair<Iter, Iter> VertexInfo;
 
+      Iter ei, ei_end;
       std::vector<VertexInfo> stack;
 
-      put(vertex_color, u, Color::gray());
-      vis.discover_vertex(u, g);
-      stack.push_back(std::make_pair(u, out_edges(u, g)));
-      while (!stack.empty()) {
-        VertexInfo& back = stack.back();
-        u = back.first;
-        Iter ei, ei_end;
-        boost::tie(ei, ei_end) = back.second;
-        stack.pop_back();
-        while (ei != ei_end) {
+      put(vertex_color, u, Color::gray());           vis.discover_vertex(u, g);
+      for (tie(ei, ei_end) = out_edges(u, g); ; ++ei) {
+        while (ei != ei_end) {                       vis.examine_edge(*ei, g);
           Vertex v = target(*ei, g);
-          vis.examine_edge(*ei, g);
           ColorValue v_color = get(vertex_color, v);
           EColorValue uv_color = get(edge_color, *ei);
           put(edge_color, *ei, EColor::black());
-          if (v_color == Color::white()) {
-            vis.tree_edge(*ei, g);
-            stack.push_back(std::make_pair(u, std::make_pair(++ei, ei_end)));
+          if (v_color == Color::white()) {           vis.tree_edge(*ei, g);
+            stack.push_back(VertexInfo(ei, ei_end));
             u = v;
-            put(vertex_color, u, Color::gray());
-            vis.discover_vertex(u, g);
-            boost::tie(ei, ei_end) = out_edges(u, g);
-          } else if (v_color == Color::gray()) {
-            if (uv_color == EColor::white()) vis.back_edge(*ei, g);
-            ++ei;
-          } else { // if (v_color == Color::black())
+            put(vertex_color, u, Color::gray());     vis.discover_vertex(u, g);
+            tie(ei, ei_end) = out_edges(u, g);
+          } else {
+            if ((v_color == Color::gray()) && (uv_color == EColor::white()))
+                                                     vis.back_edge(*ei, g);
+                                                     vis.finish_edge(*ei, g);
             ++ei;
           }
         }
-        put(vertex_color, u, Color::black());
-        vis.finish_vertex(u, g);
+        put(vertex_color, u, Color::black());        vis.finish_vertex(u, g);
+        if (stack.empty()) break;
+        tie(ei, ei_end) = stack.back();
+        u = source(*ei, g);
+        stack.pop_back();                            vis.finish_edge(*ei, g);
       }
     }
 
@@ -118 +112 @@
           undir_dfv_impl(g, v, vis, vertex_color, edge_color);
         } else if (v_color == Color::gray() && uv_color == EColor::white())
                                              vis.back_edge(*ei, g);
+                                             vis.finish_edge(*ei, g);
       }
       put(vertex_color, u, Color::black());  vis.finish_vertex(u, g);
     }

boost/graph/visitors.hpp

@@ -44 +44 @@
       on_discover_vertex_num, on_finish_vertex_num, on_examine_vertex_num,
       on_examine_edge_num, on_tree_edge_num, on_non_tree_edge_num,
       on_gray_target_num, on_black_target_num,
-      on_forward_or_cross_edge_num, on_back_edge_num,
+      on_forward_or_cross_edge_num, on_back_edge_num, on_finish_edge_num,
       on_edge_relaxed_num, on_edge_not_relaxed_num,
       on_edge_minimized_num, on_edge_not_minimized_num
     };
@@ -75 +75 @@
   struct on_forward_or_cross_edge {
     enum { num = detail::on_forward_or_cross_edge_num }; };
   struct on_back_edge { enum { num = detail::on_back_edge_num }; };
+  struct on_finish_edge { enum { num = detail::on_finish_edge_num }; };
 
   struct on_edge_relaxed { enum { num = detail::on_edge_relaxed_num }; };
   struct on_edge_not_relaxed {

libs/graph/doc/DFSVisitor.html

@@ -150 +150 @@
 </tr>
 
 <tr>
+<td>Finish Edge</td>
+<td><tt>vis.finish_edge(e, g)</tt></td>
+<td><tt>void</tt></td>
+<td>
+This is invoked on each non-tree edge as well as on each tree edge after
+<tt>finish_vertex</tt> has been called on its target vertex.</td>
+</tr>
+
+<tr>
 <td>Finish Vertex</td>
 <td><tt>vis.finish_vertex(u, g)</tt></td>
 <td><tt>void</tt></td>

libs/graph/doc/depth_first_search.html

@@ -107 +107 @@
       <i>...</i>
     <b>else if</b> (<i>color[v] =</i> BLACK) 
       <i>...</i>
+    <i>...</i>
   <b>end for</b>
   <i>color[u] :=</i> BLACK
   <i>f_time[u] := time := time + 1</i> 
@@ -139 +140 @@
 <i>(u,v)</i> is a back edge
 -
 <i>(u,v)</i> is a cross or forward edge
+finish edge <i>(u,v)</i>
 -
 finish vertex <i>u</i>
 -
@@ -249 +251 @@
 
 <li><b><tt>vis.start_vertex(s, g)</tt></b> is invoked on the source
   vertex once before the start of the search.
-  
+
 <li><b><tt>vis.discover_vertex(u, g)</tt></b> is invoked when a vertex
   is encountered for the first time.
   
@@ -259 +261 @@
 <li><b><tt>vis.tree_edge(e, g)</tt></b> is invoked on each edge as it
   becomes a member of the edges that form the search tree. If you
   wish to record predecessors, do so at this event point.
-  
+
 <li><b><tt>vis.back_edge(e, g)</tt></b> is invoked on the back edges in
   the graph.
-  
+
 <li><b><tt>vis.forward_or_cross_edge(e, g)</tt></b> is invoked on
   forward or cross edges in the graph. In an undirected graph this
   method is never called.
-  
+
+<li><b><tt>vis.finish_edge(e, g)</tt></b> is invoked on the non-tree edges in
+  the graph as well as on each tree edge after its target vertex is finished.
+
 <li><b><tt>vis.finish_vertex(u, g)</tt></b> is invoked on a vertex after
   all of its out edges have been added to the search tree and all of
   the adjacent vertices have been discovered (but before their

libs/graph/doc/undirected_dfs.html

@@ -7 +7 @@
      http://www.boost.org/LICENSE_1_0.txt)
   -->
 <Head>
-<Title>Boost Graph Library: Depth-First Search</Title>
+<Title>Boost Graph Library: Undirected Depth-First Search</Title>
 <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" 
         ALINK="#ff0000"> 
 <IMG SRC="../../../boost.png" 
@@ -116 +116 @@
       <b>call</b> DFS-VISIT(<i>G</i>, <i>v</i>)
     <b>else if</b> (<i>vcolor[v] =</i> GRAY and <i>ec =</i> WHITE)
       <i>...</i>
+    <i>...</i>
   <b>end for</b>
   <i>vcolor[u] :=</i> BLACK
   <i>f_time[u] := time := time + 1</i> 
@@ -151 +152 @@
 -
 <i>(u,v)</i> is a back edge
 -
+finish edge <i>(u,v)</i>
 -
 finish vertex <i>u</i>
 -
@@ -277 +279 @@
 
 <li><b><tt>vis.start_vertex(s, g)</tt></b> is invoked on the source
   vertex once before the start of the search.
-  
+
 <li><b><tt>vis.discover_vertex(u, g)</tt></b> is invoked when a vertex
   is encountered for the first time.
-  
+
 <li><b><tt>vis.examine_edge(e, g)</tt></b> is invoked on every out-edge
   of each vertex after it is discovered.
 
 <li><b><tt>vis.tree_edge(e, g)</tt></b> is invoked on each edge as it
   becomes a member of the edges that form the search tree. If you
   wish to record predecessors, do so at this event point.
-  
+
 <li><b><tt>vis.back_edge(e, g)</tt></b> is invoked on the back edges in
   the graph. 
 
+<li><b><tt>vis.finish_edge(e, g)</tt></b> is invoked on the back edges in
+  the graph as well as on each tree edge after its target vertex is finished.
+
 <li><b><tt>vis.finish_vertex(u, g)</tt></b> is invoked on a vertex after
   all of its out edges have been added to the search tree and all of
   the adjacent vertices have been discovered (but before their

libs/graph/example/dfs.cpp

@@ -27 +27 @@
   Tree edge: 0 --> 2
   Tree edge: 2 --> 1
   Back edge: 1 --> 1
+  Finish edge: 1 --> 1
   Tree edge: 1 --> 3
   Back edge: 3 --> 1
+  Finish edge: 3 --> 1
   Tree edge: 3 --> 4
   Back edge: 4 --> 0
+  Finish edge: 4 --> 0
   Back edge: 4 --> 1
+  Finish edge: 4 --> 1
+  Finish edge: 3 --> 4
+  Finish edge: 1 --> 3
+  Finish edge: 2 --> 1
   Forward or cross edge: 2 --> 3
+  Finish edge: 2 --> 3
+  Finish edge: 0 --> 2
   1 10
   3 8
   2 9
@@ -69 +78 @@
          << " --> " <<  target(e, G) << endl;
     Base::forward_or_cross_edge(e, G);
   }
+  template <class Edge, class Graph>
+  void finish_edge(Edge e, Graph& G) {
+    cout << "Finish edge: " << source(e, G) <<
+      " --> " <<  target(e, G) << endl;
+    Base::finish_edge(e, G);
+  }
 };
 template <class VisitorList>
 edge_categorizer<VisitorList>

libs/graph/example/dfs.expected

@@ -1 +1 @@
 Tree edge: 0 --> 2
 Tree edge: 2 --> 1
 Back edge: 1 --> 1
+Finish edge: 1 --> 1
 Tree edge: 1 --> 3
 Back edge: 3 --> 1
+Finish edge: 3 --> 1
 Tree edge: 3 --> 4
 Back edge: 4 --> 0
+Finish edge: 4 --> 0
 Back edge: 4 --> 1
+Finish edge: 4 --> 1
+Finish edge: 3 --> 4
+Finish edge: 1 --> 3
+Finish edge: 2 --> 1
 Forward or cross edge: 2 --> 3
+Finish edge: 2 --> 3
+Finish edge: 0 --> 2
 1 10
 3 8
 2 9

libs/graph/test/Jamfile.v2

@@ -42 +42 @@
     [ run csr_graph_test.cpp : : : : : <variant>release ]
     [ run dag_longest_paths.cpp ]
     [ run dfs.cpp ../../test/build//boost_test_exec_monitor ]
+    [ run undirected_dfs.cpp ../../test/build//boost_test_exec_monitor ]
     [ compile dfs_cc.cpp ]
     [ compile dijkstra_cc.cpp ]
     [ run dijkstra_heap_performance.cpp : 10000 ]

libs/graph/test/dfs.cpp

@@ -68 +68 @@
     using namespace boost;
     BOOST_CHECK( get(m_color, target(e, g)) == Color::black() );
   }
+  template <class Edge, class Graph>
+  void finish_edge(Edge e, Graph& g) {
+    using namespace boost;
+    BOOST_CHECK(
+        (get(m_color, target(e, g)) == Color::gray())
+     || (get(m_color, target(e, g)) == Color::black())
+    );
+  }
   template <class Vertex, class Graph>
   void finish_vertex(Vertex u, Graph&) {
     using namespace boost;