/**************************************************************************************
* 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.epl.named;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.expression.ExprEvaluator;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An iterator that filters events suppied by another iterator,
* using a list of one or more filter expressions as filter.
*/
public class FilteredEventIterator implements Iterator<EventBean>
{
private final Iterator<EventBean> parent;
private final ExprEvaluator[] filterList;
private final EventBean[] eventPerStream = new EventBean[1];
private final ExprEvaluatorContext exprEvaluatorContext;
private EventBean next;
/**
* Ctor.
* @param filters is a list of expression nodes for filtering
* @param parent is the iterator supplying the events to apply the filter on
* @param exprEvaluatorContext context for expression evalauation
*/
public FilteredEventIterator(ExprEvaluator[] filters, Iterator<EventBean> parent, ExprEvaluatorContext exprEvaluatorContext)
{
this.parent = parent;
this.filterList = filters;
this.exprEvaluatorContext = exprEvaluatorContext;
getNext();
}
public boolean hasNext()
{
return next != null;
}
public EventBean next()
{
if (next == null)
{
throw new NoSuchElementException();
}
EventBean result = next;
getNext();
return result;
}
public void remove()
{
throw new UnsupportedOperationException();
}
private void getNext()
{
if ((filterList == null) || (filterList.length == 0))
{
if (parent.hasNext())
{
next = parent.next();
}
else
{
next = null;
}
return;
}
while(parent.hasNext())
{
next = parent.next();
eventPerStream[0] = next;
boolean pass = true;
for (ExprEvaluator filter : filterList)
{
Boolean result = (Boolean) filter.evaluate(eventPerStream, true, exprEvaluatorContext);
if (result == null || !result)
{
pass = false;
break;
}
}
if (pass)
{
return;
}
}
next = null;
}
}