// Check for unique parts   
Cd_graph { 
{{
  HashSet uniqueParts = new HashSet();

  public void check_unique(ClassGraph cg1) {

    Strategy s1 = new Strategy("from Cd_graph through Adjacency to Vertex");
    TraversalGraph tg = new TraversalGraph(s1, cg1);
    
    tg.traverse(this, new Visitor() {
     
      private Vertex defined_vertex;
      private Vertex current_vertex;

      public void before (Construct_ns host) {
        	uniqueParts = new HashSet();
        	defined_vertex = current_vertex;
      }

      public void before (Regular host) {
        	AddToStack(host.get_vertex().get_vertex().get_vertex_name().toString().toLowerCase());
      }
        
      public void before (Labeled host) {
        	AddToStack( host.get_label_name().toString() );
      } 
      
      public void before (Vertex host) {
        	current_vertex = host;
      }

      private void AddToStack (String add) {
        	//If class already defined, produce error message
		if (uniqueParts.contains(add)) {
          	System.err.println(" ERROR: Part " + add + " of the class " +
                               defined_vertex.get_vertex_name() + " is not unique. ");
		}
        	else { 
			//Add to list of defined classes
			uniqueParts.add(add); 
		}
      }
  
    }); // End of traversal
  } // end of check_unique
}}

}