001/*
002 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 *  This file is licensed to You under the Eclipse Public License (EPL);
005 *  You may not use this file except in compliance with the License. You
006 *  may obtain a copy of the License at
007 *
008 *      http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 *  See the COPYRIGHT.txt file distributed with this work for information
011 *  regarding copyright ownership.
012 */
013package org.jikesrvm.compilers.opt.liveness;
014
015import java.util.Enumeration;
016
017import org.jikesrvm.compilers.opt.regalloc.LiveIntervalElement;
018
019/**
020 * Enumerator for a list of live intervals stored on a basic block.
021 * <p>
022 * Note: This is fragile.  Use with care iff you know what you're doing.
023 * TODO: redesign the way live info is stored on the IR to be a bit more
024 * robust.
025 */
026public class LiveIntervalEnumeration implements Enumeration<LiveIntervalElement> {
027  private LiveIntervalElement currentElement;
028
029  /**
030   * @param first  The first live interval in a list to be enumerated
031   */
032  public LiveIntervalEnumeration(LiveIntervalElement first) {
033    this.currentElement = first;
034  }
035
036  @Override
037  public boolean hasMoreElements() {
038    return currentElement != null;
039  }
040
041  @Override
042  public LiveIntervalElement nextElement() {
043    LiveIntervalElement result = currentElement;
044    currentElement = currentElement.getNext();
045    return result;
046  }
047}