/**************************************************************************************
 * Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 * http://esper.codehaus.org                                                          *
 * http://www.espertech.com                                                           *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the GPL license       *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package com.espertech.esper.util;

import org.w3c.dom.NodeList;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

import java.util.NoSuchElementException;
import java.util.Iterator;

/**
 * Iterator over DOM nodes that positions between elements.
 */
public class DOMElementIterator implements Iterator<Element>
{
    private int index;
    private NodeList nodeList;

    /**
     * Ctor.
     * @param nodeList is a list of DOM nodes.
     */
    public DOMElementIterator(NodeList nodeList)
    {
        this.nodeList = nodeList;
    }

    public boolean hasNext()
    {
        positionNext();
        return index < nodeList.getLength();
    }

    public Element next()
    {
        if (index >= nodeList.getLength())
        {
            throw new NoSuchElementException();
        }
        Element result = (Element) nodeList.item(index);
        index++;
        return result;
    }

    public void remove()
    {
        throw new UnsupportedOperationException();
    }

    private void positionNext()
    {
        while (index < nodeList.getLength())
        {
            Node node = nodeList.item(index);
            if (node instanceof Element)
            {
                break;
            }
            index++;
        }
    }
}