JoinedIterator.java

/*
 * Distributed as part of mchange-commons-java 0.2.11
 *
 * Copyright (C) 2015 Machinery For Change, Inc.
 *
 * Author: Steve Waldman <swaldman@mchange.com>
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of EITHER:
 *
 *     1) The GNU Lesser General Public License (LGPL), version 2.1, as 
 *        published by the Free Software Foundation
 *
 * OR
 *
 *     2) The Eclipse Public License (EPL), version 1.0
 *
 * You may choose which license to accept if you wish to redistribute
 * or modify this work. You may offer derivatives of this work
 * under the license you have chosen, or you may provide the same
 * choice of license which you have been offered here.
 *
 * This software 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.
 *
 * You should have received copies of both LGPL v2.1 and EPL v1.0
 * along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
 * If not, the text of these licenses are currently available at
 *
 * LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 *  EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php 
 * 
 */

package com.mchange.v1.util;

import java.util.*;

public class JoinedIterator implements Iterator
{
    Iterator[] its;
    Iterator   removeIterator = null;
    boolean    permit_removes;
    int        cur = 0;

    public JoinedIterator(Iterator[] its, boolean permit_removes)
    {
	this.its = its;
	this.permit_removes = permit_removes;
    }

    public boolean hasNext()
    {
	if (cur == its.length)
	    return false;
	else if (its[ cur ].hasNext())
	    return true;
	else
	    {
		++cur;
		return this.hasNext();
	    }
    }

    public Object next()
    {
	if (! this.hasNext())
	    throw new NoSuchElementException();

	removeIterator = its[cur];
	return removeIterator.next();
    }

    public void remove()
    {
	if (permit_removes)
	    {
		if (removeIterator != null)
		    {
			removeIterator.remove();
			removeIterator = null;
		    }
		else
		    throw new IllegalStateException("next() not called, or element already removed.");
	    }
	else
	    throw new UnsupportedOperationException();
    }
}