EmptyEventStream.java

package org.epics.archiverappliance.common;

import java.io.IOException;
import java.util.Iterator;

import org.epics.archiverappliance.Event;
import org.epics.archiverappliance.EventStream;
import org.epics.archiverappliance.config.ArchDBRTypes;
import org.epics.archiverappliance.retrieval.RemotableEventStreamDesc;
import org.epics.archiverappliance.retrieval.RemotableOverRaw;

/**
 * Instead of returning null, in some cases, it may be more convenient to return a EventStream with no events
 * @author mshankar
 *
 */
public class EmptyEventStream implements EventStream, RemotableOverRaw {
	RemotableEventStreamDesc desc = null;
	public EmptyEventStream(String pvName, ArchDBRTypes type) {
		desc = new RemotableEventStreamDesc(type, pvName, TimeUtils.getCurrentYear());
	}

	@Override
	public Iterator<Event> iterator() {
		return new Iterator<Event>() {
			@Override
			public boolean hasNext() {
				return false;
			}

			@Override
			public Event next() {
				return null;
			}

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

	@Override
	public void close() throws IOException {
	}

	@Override
	public RemotableEventStreamDesc getDescription() {
		return desc;
	}

}