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     */
013    package org.jikesrvm.compilers.opt.liveness;
014    
015    import java.util.Enumeration;
016    import java.util.NoSuchElementException;
017    
018    import org.jikesrvm.compilers.opt.ir.operand.RegisterOperand;
019    
020    /**
021     * An enumeration over live set lists
022     */
023    public class LiveSetEnumerator implements Enumeration<RegisterOperand> {
024    
025      /**
026       *  the current element on this list
027       */
028      private LiveSetElement current;
029    
030      /**
031       * The constructor
032       * @param   list  The {@link LiveSetElement} at the head of the list.
033       */
034      public LiveSetEnumerator(LiveSetElement list) {
035        current = list;
036      }
037    
038      /**
039       * Are there any more elements?
040       * @return whether there are any more elements?
041       */
042      public boolean hasMoreElements() {
043        return current != null;
044      }
045    
046      /**
047       * Returns the next element, if one exists, otherwise throws an exception
048       * @return the next element, if one exists, otherwise throws an exception
049       */
050      public RegisterOperand nextElement() {
051        if (current != null) {
052          LiveSetElement ret = current;
053          current = current.getNext();
054          return ret.getRegisterOperand();
055        } else {
056          throw new NoSuchElementException("LiveSetEnumerator");
057        }
058      }
059    }
060    
061    
062