EDIT

/**

* Copyright (C) 2009 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.io.markup;

import java.util.ArrayList;

import java.util.List;

import javax.xml.stream.XMLEventReader;

import javax.xml.stream.XMLStreamException;

import javax.xml.stream.events.StartElement;

import javax.xml.stream.events.XMLEvent;

import org.apache.log4j.Logger;

/**

 * @author a.mueller

 * @date 28.06.2011

 *

 */

public class LookAheadEventReader implements XMLEventReader {

	private static final Logger logger = Logger.getLogger(LookAheadEventReader.class);

	private XMLEventReader reader;

	private List<XMLEvent> cachedEvents = new ArrayList<XMLEvent>();

	private List<XMLEvent> usedEvents = new ArrayList<XMLEvent>();

	public LookAheadEventReader(StartElement startElement, XMLEventReader parentReader) throws XMLStreamException{

		int depth = 0;

		this.reader = parentReader;

		XMLEvent next = parentReader.nextEvent();

		while (! next.isEndElement() || 

				 ! next.asEndElement().getName().equals(startElement.getName()) ||

				 depth > 0){

			cachedEvents.add(next);

			if (next.isStartElement() && next.asStartElement().getName().equals(startElement.getName())){

				depth++;

			}else if (next.isEndElement() && next.asEndElement().getName().equals(startElement.getName())){

				depth--;

			}

			next = reader.nextEvent();

		}

		cachedEvents.add(next);

	}

	@Override

	public Object next() {

		throw new RuntimeException("Iterator methods are not supported by this EventReader");

	}

	@Override

	public void remove() {

		throw new RuntimeException("Iterator methods are not supported by this EventReader");

	}

	@Override

	public XMLEvent nextEvent() throws XMLStreamException {

		if (! cachedEvents.isEmpty()){

			XMLEvent result = cachedEvents.get(0);

			XMLEvent removedEvent = cachedEvents.remove(0);

			usedEvents.add(removedEvent);

			return result;

		}else{

			logger.warn("LookAheadReader reads uncached data. This is not ");

			throw new IllegalStateException("LookAheadReader reads uncached data. This is not ");

//			return reader.nextEvent();

		}

	}

	@Override

	public boolean hasNext() {

		return reader.hasNext();

	}

	@Override

	public XMLEvent peek() throws XMLStreamException {

		return reader.peek();

	}

	@Override

	public String getElementText() throws XMLStreamException {

		return reader.getElementText();

	}

	@Override

	public XMLEvent nextTag() throws XMLStreamException {

		return reader.nextTag();

	}

	@Override

	public Object getProperty(String name) throws IllegalArgumentException {

		return reader.getProperty(name);

	}

	@Override

	public void close() throws XMLStreamException {

		reader.close();

	}

	public boolean previousWasEnd(String name){

		return hasStartElement(name, -1, 0);

	}

	public boolean nextIsStart(String name){

		return hasStartElement(name, 0, 1);

	}

	public boolean hasStartElement(String name, int start, int end){

		if (start < 0 ){

			start = 0;

		}

		if (end > cachedEvents.size()){

			end = cachedEvents.size();

		}

		for (int i = start; i < end; i++){

			XMLEvent ev = cachedEvents.get(i);

			if (ev.isStartElement() && ev.asStartElement().getName().getLocalPart().equals(name)){

				return true;

			}

		}

		return false;

	}

	public boolean hasEndElement(String name, int start, int end){

		if (end > 0 ){

			end = 0;

		}

		if (-start > usedEvents.size()){

			start = -cachedEvents.size();

		}

		for (int i = start; i < end; i++){

			XMLEvent ev = cachedEvents.get( cachedEvents.size() + i );

			if (ev.isEndElement() && ev.asEndElement().getName().getLocalPart().equals(name)){

				return true;

			}

		}

		return false;

	}

}