From 86ef70716434ea1dabe2b6a25bb489e19793ebfe Mon Sep 17 00:00:00 2001
From: Jeremy Siek <jeremy.siek@gmail.com>
Date: Tue, 6 Feb 2001 19:40:26 +0000
Subject: [PATCH] added is_connected

[SVN r8986]
---
 include/boost/graph/graph_utility.hpp | 49 ++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/include/boost/graph/graph_utility.hpp b/include/boost/graph/graph_utility.hpp
index 18ecb2db..e2eabe37 100644
--- a/include/boost/graph/graph_utility.hpp
+++ b/include/boost/graph/graph_utility.hpp
@@ -313,8 +313,12 @@ namespace boost {
   }
 
   // is x a descendant of y?
-  template <typename Node, typename ParentMap>
-  inline bool is_descendant(Node x, Node y, ParentMap parent) {
+  template <typename ParentMap>
+  inline bool is_descendant
+  (typename property_traits<ParentMap>::value_type x,
+   typename property_traits<ParentMap>::value_type y,
+   ParentMap parent) 
+  {
     if (get(parent, x) == x) // x is the root of the tree
       return false;
     else if (get(parent, x) == y)
@@ -324,19 +328,48 @@ namespace boost {
   }
 
   // is y reachable from x?
-  template <typename Graph, typename ColorMap>
+  template <typename IncidenceGraph, typename VertexColorMap>
   inline bool is_reachable
-    (typename graph_traits<Graph>::vertex_descriptor x,
-     typename graph_traits<Graph>::vertex_descriptor y,
-     const Graph& g,
-     ColorMap color) // should be white for every vertex
+    (typename graph_traits<IncidenceGraph>::vertex_descriptor x,
+     typename graph_traits<IncidenceGraph>::vertex_descriptor y,
+     const IncidenceGraph& g,
+     VertexColorMap color) // should start out white for every vertex
   {
-    typedef typename property_traits<ColorMap>::value_type ColorValue;
+    typedef typename property_traits<VertexColorMap>::value_type ColorValue;
     dfs_visitor<> vis;
     depth_first_visit(g, x, vis, color);
     return get(color, y) != color_traits<ColorValue>::white();
   }
 
+  // Is the undirected graph connected?
+  // Is the directed graph strongly connected?
+  template <typename VertexListGraph, typename VertexColorMap>
+  inline bool is_connected(const VertexListGraph& g, VertexColorMap color)
+  {
+    typedef typename property_traits<VertexColorMap>::value_type ColorValue;
+    typedef color_traits<ColorValue> Color;
+    typename graph_traits<VertexListGraph>::vertex_iterator 
+      ui, ui_end, vi, vi_end, ci, ci_end;
+    for (tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui)
+      for (tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
+	if (*ui != *vi) {
+	  for (tie(ci, ci_end) = vertices(g); ci != ci_end; ++ci) 
+	    put(color, *ci, Color::white());
+	  if (! is_reachable(*ui, *vi, color))
+	    return false;
+	}
+    return true;
+  }
+
+  template <typename Graph>
+  bool is_self_loop
+    (typename graph_traits<Graph>::edge_descriptor e,
+     const Graph& g)
+  {
+    return source(e, g) == target(e, g);
+  }
+
+
   template <class T1, class T2>
   std::pair<T1,T2> 
   make_list(const T1& t1, const T2& t2)