/* Soot - a J*va Optimization Framework
* Copyright (C) 2003 Ondrej Lhotak
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
package soot.util.queue;
import java.util.*;
/** A queue of Object's. One can add objects to the queue, and they are
* later read by a QueueReader. One can create arbitrary numbers of
* QueueReader's for a queue, and each one receives all the Object's that
* are added. Only objects that have not been read by all the QueueReader's
* are kept. A QueueReader only receives the Object's added to the queue
* <b>after</b> the QueueReader was created.
* @author Ondrej Lhotak
*/
public class QueueReader<E> implements java.util.Iterator<E>
{
private E[] q;
private int index;
QueueReader( E[] q, int index ) {
this.q = q;
this.index = index;
}
/** Returns (and removes) the next object in the queue, or null if
* there are none. */
@SuppressWarnings("unchecked")
public final E next() {
if( q[index] == null ) throw new NoSuchElementException();
if( index == q.length - 1 ) {
q = (E[]) q[index];
index = 0;
if( q[index] == null ) throw new NoSuchElementException();
}
E ret = q[index];
if( ret == ChunkedQueue.NULL_CONST ) ret = null;
index++;
return ret;
}
/** Returns true iff there is currently another object in the queue. */
@SuppressWarnings("unchecked")
public final boolean hasNext() {
if (q[index] == null) return false;
if (index == q.length - 1) {
q = (E[]) q[index];
index = 0;
if (q[index] == null) return false;
}
return true;
}
public final void remove() {
throw new UnsupportedOperationException();
}
public final QueueReader<E> clone() {
return new QueueReader<E>( q, index );
}
}