BaseDemoInputStream.java

/*
  BaseDemoInputStream.java

  (c) 2012-2013 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.engine.demos.stream;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

import v9t9.common.demos.IDemoEvent;
import v9t9.common.demos.IDemoInputBuffer;
import v9t9.common.demos.IDemoInputStream;

/**
 * @author ejs
 *
 */
public abstract class BaseDemoInputStream extends BaseReader implements IDemoInputStream {
	
	protected List<IDemoInputBuffer> buffers = new ArrayList<IDemoInputBuffer>(4);
	
	protected Queue<IDemoEvent> queuedEvents;

	public BaseDemoInputStream(InputStream is_) {
		super(is_);

		queuedEvents = new LinkedList<IDemoEvent>();
		

	}

	public void close() throws IOException {
		if (is != null) {
			is.close();
			is = null;
		}
	}

	@Override
	public IDemoEvent readNext() throws IOException {
		try {
			if (is != null && queuedEvents.isEmpty()) {
				ensureEvents();
			}
		} catch (IOException e) {
			throw e;
		} catch (Throwable e) {
			throw new IOException("Error reading demo at 0x" + 
					Long.toHexString(getPosition()), e);
		}
		
		return queuedEvents.poll();
	}

	/**
	 * Read from the input stream and queue events into queuedEvents.
	 * If stream is empty, just return.
	 * @throws IOException
	 */
	protected abstract void ensureEvents() throws IOException;
}