EDIT

/**

* Copyright (C) 2007 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.stream;

import java.util.Queue;

import java.util.concurrent.LinkedBlockingQueue;

import org.apache.logging.log4j.LogManager;import org.apache.logging.log4j.Logger;

import eu.etaxonomy.cdm.io.stream.terms.TermUri;

/**

 * @author a.mueller

 *

 */

public class LookAheadStream<ITEM> implements INamespaceReader<ITEM>{

	@SuppressWarnings("unused")

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

	private final Queue<ITEM> fifo = new LinkedBlockingQueue<>();

	private final INamespaceReader<ITEM> stream;

	public LookAheadStream(INamespaceReader<ITEM> stream) {

		super();

		this.stream = stream;

		if (stream == null){

			throw new RuntimeException("Stream may not be null.");

		}

	}

	@Override

    public ITEM read(){

		if (! fifo.isEmpty()){

			return fifo.remove();

		}else{

			return stream.read();

		}

	}

	public ITEM readLookAhead(int max){

	    if (max > fifo.size()){

	        ITEM result = stream.read();

	        fifo.add(result);

	        return result;

	    }else{

	        return null;

	    }

	}

	public ITEM readLookAhead(){

		ITEM result = stream.read();

	    fifo.add(result);

	    return result;

	}

	public boolean hasNextLookAhead(int max){

		if (fifo.size() < max && stream.hasNext()){

			return true;

		}else{

			return false;

		}

	}

	public int sizeLookAhead(){

		return fifo.size();

	}

	public boolean isLookingAhead(){

		return ! fifo.isEmpty();

	}

	@Override

	public boolean hasNext() {

		return ! fifo.isEmpty() || stream.hasNext();

	}

	@Override

	public TermUri getTerm() {

		return stream.getTerm();

	}

}