better integrity check

src/edmonds.cpp

@@ -8,10 +8,28 @@ using namespace ED;
 
 namespace Edmonds {
 
-void check_integrity(GraphAttributes & attrs)
+NodeId get_rho(GraphAttributes const & attrs, NodeId id)
+{
+   while(attrs.rho_[id] != id)
+   {
+      id = attrs.rho_[id];
+   }
+   return id;
+}
+
+void check_integrity(GraphAttributes const & attrs)
 {
    for(NodeId id = 0; id < attrs.num_nodes(); ++id)
    {
+      // Check that rho does not have any cycles
+      NodeId cur_rho_id = id;
+      size_t count = attrs.num_nodes();
+      while(attrs.rho_[cur_rho_id] != cur_rho_id and count--)
+      {
+         cur_rho_id = attrs.rho_[cur_rho_id];
+      }
+      assert(count != 0);
+
       // Check that μ encodes a valid matching
       NodeId matched = attrs.mu[id];
       if(matched != id)
@@ -22,13 +40,13 @@ void check_integrity(GraphAttributes & attrs)
       if (attrs.is_out_of_forest(id))
       {
          assert(attrs.phi[id] == id);
-         assert(attrs.rho(id) == id);
+         assert(get_rho(attrs, id) == id);
       }
       else
       {
          // check for a path to the root, i.e. ρ(node)
          NodeId cur_node = id;
-         while(cur_node != attrs.rho(cur_node))
+         while(cur_node != get_rho(attrs, cur_node))
          {
             // If the condition was true, then cur_node is outer, part of a blossom
             // and we want to follow its path
@@ -36,8 +54,8 @@ void check_integrity(GraphAttributes & attrs)
             // and point to vertices that have the same rho
             assert(attrs.mu[cur_node] != cur_node);
             assert(attrs.phi[cur_node] != cur_node);
-            assert(attrs.rho(attrs.mu[cur_node]) == attrs.rho(cur_node));
-            assert(attrs.rho(attrs.phi[cur_node]) == attrs.rho(cur_node));
+            assert(get_rho(attrs,attrs.mu[cur_node]) == get_rho(attrs,cur_node));
+            assert(get_rho(attrs,attrs.phi[cur_node]) == get_rho(attrs,cur_node));
 
             // now, walk along the matched edge
             cur_node = attrs.mu[cur_node];
@@ -46,7 +64,7 @@ void check_integrity(GraphAttributes & attrs)
             // - not be the identity
             // - result in a node that has the same rho
             assert(attrs.phi[cur_node] != cur_node);
-            assert(attrs.rho(attrs.phi[cur_node]) == attrs.rho(cur_node));
+            assert(get_rho(attrs, attrs.phi[cur_node]) == get_rho(attrs,cur_node));
 
             cur_node = attrs.mu[attrs.phi[cur_node]];
          }
@@ -54,7 +72,7 @@ void check_integrity(GraphAttributes & attrs)
 
       if (not attrs.is_outer(id))
       {
-         assert(attrs.rho(id) == id);
+         assert(get_rho(attrs,id) == id);
       }
    }
 }