Cd_graph {
{{
    public void checkInheritanceCycle(final ClassGraph cg) {

    //everything in construct_ns of the Neighbors_wc objects is noise
    Strategy s = new Strategy("from Cd_graph bypassing {-> *,construct_ns, *} to Vertex");

    cg.traverse(this, s, new Visitor() {
  
      public Vector keyList;  		//this is a list of keys we will be adding to the hash table
      public Map hashCheck;   		//keys are classes that inherit, values are a list classes the key inherits from

      public Vector getKeyList(String key) {return (Vector) hashCheck.get(String.valueOf(key));}

      public void start() {hashCheck = new HashMap();}

      public void before(Alternat_ns host) {keyList = new Vector();}

      public void before(Vertex host) {
        String vname = host.get_vertex_name().toString();

        // Add this vertex name to the keyList
        if (keyList != null) keyList.add(vname);

      }
      public void after (Adjacency host) {

        // if the keyList is null, then there is no work to be done
        if (keyList != null) {
          Vector valueList = new Vector();

          String sourceName = host.get_source().get_vertex_name().toString();
          buildInheritsFromList(sourceName, sourceName, valueList);

          Iterator i = keyList.iterator();
          while (i.hasNext()) {
            String checkingKey = (String) i.next();
            if (valueList.contains(checkingKey)){
              String message = new String(" *** ERROR: Cyclic inheritance from ");
              for (int list = valueList.size() - 1; list >= 0; list--) 
		message = message + "class " + valueList.get(list) + " to ";
              message = message + "class " + checkingKey;          
              System.out.println(message);
	      System.out.print("...Fatal error, aborting.");
	      System.exit(1);
            }

            // add the entry to the hash table
            hashCheck.put(checkingKey, valueList.clone());

          } // end for loop
 
          valueList = null;    
          keyList = null;

        } 
      }// End after adjacency
      
      public void buildInheritsFromList(String sourceName, String stopAtVertex, Vector valueList){
            
        //This is a recursive function that builds valueList. It takes a sourceName, and adds all classes it inherits from, 
	//along with all classes that those classes inherit from
        
        valueList.add(sourceName);
        if (hashCheck.keySet().contains(sourceName)){
          if (!getKeyList(sourceName).contains(stopAtVertex)){ 
            String nextValue = (String) getKeyList(sourceName).get(0);
            buildInheritsFromList(nextValue, stopAtVertex, valueList);
          }
        }
      }  
    });
  }
}}
}