164     public Set<String> keySet() {
 165         return values.keySet();
 166     }
 167 
 168     public int size() {
 169         return values.size();
 170     }
 171 
 172     // light-weight notification mechanism
 173 
 174     private List<Runnable> listeners = List.nil();
 175 
 176     public void addListener(Runnable listener) {
 177         listeners = listeners.prepend(listener);
 178     }
 179 
 180     public void notifyListeners() {
 181         for (Runnable r: listeners)
 182             r.run();
 183     }





 184 }

 164     public Set<String> keySet() {
 165         return values.keySet();
 166     }
 167 
 168     public int size() {
 169         return values.size();
 170     }
 171 
 172     // light-weight notification mechanism
 173 
 174     private List<Runnable> listeners = List.nil();
 175 
 176     public void addListener(Runnable listener) {
 177         listeners = listeners.prepend(listener);
 178     }
 179 
 180     public void notifyListeners() {
 181         for (Runnable r: listeners)
 182             r.run();
 183     }
 184 
 185     public void clear() {
 186         values.clear();
 187         listeners = List.nil();
 188     }
 189 }