/**************************************************************************************
* 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.view;
import com.espertech.esper.epl.expression.ExprEvaluator;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.client.EventBean;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* Iterator for reading and filtering a source event iterator.
*/
public class FilterExprViewIterator implements Iterator<EventBean>
{
private final Iterator<EventBean> sourceIterator;
private final ExprEvaluator filter;
private final ExprEvaluatorContext exprEvaluatorContext;
private final EventBean[] evalEventArr;
private EventBean nextResult;
/**
* Ctor.
* @param sourceIterator is the iterator supplying events to filter out.
* @param filter is the filter expression
* @param exprEvaluatorContext context for expression evalauation
*/
public FilterExprViewIterator(Iterator<EventBean> sourceIterator, ExprEvaluator filter, ExprEvaluatorContext exprEvaluatorContext)
{
this.sourceIterator = sourceIterator;
this.filter = filter;
this.exprEvaluatorContext = exprEvaluatorContext;
evalEventArr = new EventBean[1];
}
public boolean hasNext()
{
if (nextResult != null)
{
return true;
}
findNext();
if (nextResult != null)
{
return true;
}
return false;
}
public EventBean next()
{
if (nextResult != null)
{
EventBean result = nextResult;
nextResult = null;
return result;
}
findNext();
if (nextResult != null)
{
EventBean result = nextResult;
nextResult = null;
return result;
}
throw new NoSuchElementException();
}
private void findNext()
{
while(sourceIterator.hasNext())
{
EventBean candidate = sourceIterator.next();
evalEventArr[0] = candidate;
Boolean pass = (Boolean) filter.evaluate(evalEventArr, true, exprEvaluatorContext);
if ((pass != null) && (pass))
{
nextResult = candidate;
break;
}
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
}