/**
 * IDList.java  1.01 97/15/09 Merlin Hughes
 *
 * Copyright (c) 1997 Merlin Hughes. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * for non-commercial purposes and without fee is hereby granted
 * provided that this copyright notice appears in all copies.
 *
 * http://merlin.org/                          merlin@merlin.org
 */

package org.merlin.step.dec;

import java.io.*;
import java.util.*;

public class IDList implements Serializable, Cloneable {
  protected Vector list = new Vector ();
  protected Vector ids = new Vector ();

  public synchronized Object addElement (Object element) {
    Object id = new Integer (System.identityHashCode (element));
    addElementWithID (id, element);
    return id;
  }

  public synchronized void addElementWithID (Object id, Object element) {
    ++ updateCount;
    ids.addElement (id);
    list.addElement (element);
  }

  public synchronized Object replaceElement (Object oldID, Object element) {
    ++ updateCount;
    int idx = ids.indexOf (oldID);
    if (idx >= 0) {
      ids.removeElementAt (idx);
      list.removeElementAt (idx);
      return addElement (element);
    } else {
      return null;
    }
  }

  public synchronized boolean replaceElementWithID (Object oldID, Object id, Object element) {
    ++ updateCount;
    int idx = ids.indexOf (oldID);
    if (idx >= 0) {
      ids.removeElementAt (idx);
      list.removeElementAt (idx);
      ids.addElement (id);
      list.addElement (element);
      return true;
    } else {
      return false;
    }
  }

  public synchronized Object getIDOfElement (Object element) {
    int idx = list.indexOf (element);
    return (idx >= 0) ? ids.elementAt (idx) : null;
  }

  public synchronized Enumeration elements () {
    return ((Vector) list.clone ()).elements ();
  }

  public synchronized Object clone () {
    try {
      return super.clone ();
    } catch (CloneNotSupportedException ex) {
      return null;
    }
  }

  int updateCount;

  public int getUpdateCount () {
    return updateCount;
  }

  public int size () {
    return list.size ();
  }

  public synchronized Object removeFirstElement () {
    if (list.size () > 0) {
      Object id = ids.elementAt (0);
      list.removeElementAt (0);
      ids.removeElementAt (0);
      return id;
    } else {
      return null;
    }
  }

  public synchronized boolean removeElement (Object id) {
    int idx = ids.indexOf (id);
    if (idx == -1) {
      return false;
    } else {
      list.removeElementAt (idx);
      ids.removeElementAt (idx);
      return true;
    }
  }
}