// $Header: /home/cvs/jakarta-jmeter/src/htmlparser/org/htmlparser/util/IteratorImpl.java,v 1.2 2004/02/11 02:16:59 woolfel Exp $
/*
 * ====================================================================
 * Copyright 2002-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */

// The developers of JMeter and Apache are greatful to the developers
// of HTMLParser for giving Apache Software Foundation a non-exclusive
// license. The performance benefits of HTMLParser are clear and the
// users of JMeter will benefit from the hard work the HTMLParser
// team. For detailed information about HTMLParser, the project is
// hosted on sourceforge at http://htmlparser.sourceforge.net/.
//
// HTMLParser was originally created by Somik Raha in 2000. Since then
// a healthy community of users has formed and helped refine the
// design so that it is able to tackle the difficult task of parsing
// dirty HTML. Derrick Oswald is the current lead developer and was kind
// enough to assist JMeter.

package org.htmlparser.util;

import java.util.Vector;

import org.htmlparser.Node;
import org.htmlparser.NodeReader;

public class IteratorImpl implements PeekingIterator
{
    NodeReader reader;
    Vector preRead;
    String resourceLocn;
    ParserFeedback feedback;

    public IteratorImpl(NodeReader rd, String resource, ParserFeedback fb)
    {
        reader = rd;
        preRead = new Vector(25);
        resourceLocn = resource;
        feedback = fb;
    }

    public Node peek() throws ParserException
    {
        Node ret;

        if (null == reader)
            ret = null;
        else
            try
            {
                ret = reader.readElement();
                if (null != ret)
                    preRead.addElement(ret);
            }
            catch (Exception e)
            {
                StringBuffer msgBuffer = new StringBuffer();
                msgBuffer.append(
                    "Unexpected Exception occurred while reading ");
                msgBuffer.append(resourceLocn);
                msgBuffer.append(", in nextHTMLNode");
                reader.appendLineDetails(msgBuffer);
                ParserException ex =
                    new ParserException(msgBuffer.toString(), e);
                feedback.error(msgBuffer.toString(), ex);
                throw ex;
            }

        return (ret);
    }

    /**
     * Check if more nodes are available.
     * @return true if a call to nextHTMLNode() will succeed.
     */
    public boolean hasMoreNodes() throws ParserException
    {
        Node node;
        boolean ret;

        if (null == reader)
            ret = false;
        else if (0 != preRead.size())
            ret = true;
        else
            ret = !(null == peek());

        return (ret);
    }

    /**
     * Get the next node.
     * @return The next node in the HTML stream, or null if there are no more nodes.
     */
    public Node nextNode() throws ParserException
    {
        Node ret;

        if (hasMoreNodes())
            ret = (Node) preRead.remove(0);
        else
            // should perhaps throw an exception?
            ret = null;

        return (ret);
    }
}