/*
 *                    BioJava development code
 *
 * This code may be freely distributed and modified under the
 * terms of the GNU Lesser General Public Licence.  This should
 * be distributed with the code.  If you do not have a copy,
 * see:
 *
 *      http://www.gnu.org/copyleft/lesser.html
 *
 * Copyright for this code is held jointly by the individual
 * authors.  These should be listed in @author doc comments.
 *
 * For more information on the BioJava project and its aims,
 * or to join the biojava-l mailing list, visit the home page
 * at:
 *
 *      http://www.biojava.org/
 *
 */

package org.biojava.utils.cache;

import java.util.HashMap;
import java.util.Map;

import org.biojava.utils.ChangeAdapter;
import org.biojava.utils.ChangeEvent;
import org.biojava.utils.ChangeListener;
import org.biojava.utils.ChangeType;
import org.biojava.utils.Changeable;

/**
 * A cache that clears values as the keys fire ChangeEvents of a given type.
 *
 * @author Matthew Pocock
 * @since 1.1
 */

public class ChangeableCache {
  private ChangeType changeType;
  private Map cache = new HashMap();
  private ChangeListener listener = new ChangeAdapter() {
    public void postChange(ChangeEvent ce) {
      Changeable source = (Changeable) ce.getSource();
      cache.remove(source);
      source.removeChangeListener(listener);
    }
  };
  
  public ChangeableCache(ChangeType ct) {
    this.changeType = ct;
  }
  
  public void put(Object key, Object value) {
    cache.put(key, value);
    if(key instanceof Changeable) {
      ((Changeable) key).addChangeListener(listener, changeType);
    }
  }
  
  public Object get(Object key) {
    return cache.get(key);
  }
}