/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
**************************************************************************************/
package com.espertech.esper.collection;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.event.EventBeanUtility;
import com.espertech.esper.event.EventTypeSPI;
import com.espertech.esper.event.EventBeanReaderDefaultImpl;
import com.espertech.esper.event.EventBeanReader;
import java.util.ArrayDeque;
import java.util.Iterator;
/**
* Iterator for obtaining distinct events.
*/
public class EventDistinctIterator implements Iterator<EventBean>
{
private static final Iterator<EventBean> NULL_ITER = new SingleEventIterator(null);
private final Iterator<EventBean> sourceIterator;
private Iterator<EventBean> resultIterator;
private EventBeanReader eventBeanReader;
/**
* Ctor.
* @param sourceIterator is the source event iterator
* @param eventType type of event
*/
public EventDistinctIterator(Iterator<EventBean> sourceIterator, EventType eventType)
{
this.sourceIterator = sourceIterator;
if (eventType instanceof EventTypeSPI)
{
eventBeanReader = ((EventTypeSPI) eventType).getReader();
}
if (eventBeanReader == null)
{
eventBeanReader = new EventBeanReaderDefaultImpl(eventType);
}
}
public EventBean next()
{
if (resultIterator == null)
{
initialize();
}
return resultIterator.next();
}
public boolean hasNext()
{
if (resultIterator == null)
{
initialize();
}
return resultIterator.hasNext();
}
private void initialize()
{
if ((sourceIterator == null) || (!sourceIterator.hasNext()))
{
resultIterator = NULL_ITER;
return;
}
EventBean eventFirst = sourceIterator.next();
if (!sourceIterator.hasNext())
{
resultIterator = new SingleEventIterator(eventFirst);
return;
}
// read all events
ArrayDeque<EventBean> events = new ArrayDeque<EventBean>();
events.add(eventFirst);
for (;sourceIterator.hasNext();)
{
events.add(sourceIterator.next());
}
// build distinct set
EventBean[] unique = EventBeanUtility.getDistinctByProp(events, eventBeanReader);
resultIterator = new ArrayEventIterator(unique);
}
public void remove()
{
throw new UnsupportedOperationException();
}
}