/**************************************************************************************
* 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.core;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.epl.agg.service.AggregationService;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.metrics.instrumentation.InstrumentationHelper;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* Iterator for the group-by case with a row per group.
*/
public class ResultSetRowPerGroupIterator implements Iterator<EventBean>
{
private final Iterator<EventBean> sourceIterator;
private final ResultSetProcessorRowPerGroup resultSetProcessor;
private final AggregationService aggregationService;
private EventBean nextResult;
private final EventBean[] eventsPerStream;
private final Set<Object> priorSeenGroups;
private final ExprEvaluatorContext exprEvaluatorContext;
/**
* Ctor.
* @param sourceIterator is the parent view iterator
* @param resultSetProcessor for providing results
* @param aggregationService for pointing to the right aggregation row
* @param exprEvaluatorContext context for expression evalauation
*/
public ResultSetRowPerGroupIterator(Iterator<EventBean> sourceIterator, ResultSetProcessorRowPerGroup resultSetProcessor, AggregationService aggregationService, ExprEvaluatorContext exprEvaluatorContext)
{
this.sourceIterator = sourceIterator;
this.resultSetProcessor = resultSetProcessor;
this.aggregationService = aggregationService;
eventsPerStream = new EventBean[1];
priorSeenGroups = new HashSet<Object>();
this.exprEvaluatorContext = exprEvaluatorContext;
}
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();
eventsPerStream[0] = candidate;
Object groupKey = resultSetProcessor.generateGroupKey(eventsPerStream, true);
aggregationService.setCurrentAccess(groupKey, exprEvaluatorContext.getAgentInstanceId());
if (resultSetProcessor.getOptionalHavingNode() != null)
{
if (InstrumentationHelper.ENABLED) { InstrumentationHelper.get().qHavingClauseNonJoin(candidate);}
Boolean pass = (Boolean) resultSetProcessor.getOptionalHavingNode().evaluate(eventsPerStream, true, exprEvaluatorContext);
if (InstrumentationHelper.ENABLED) { InstrumentationHelper.get().aHavingClauseJoin(pass);}
if (!pass)
{
continue;
}
}
if (priorSeenGroups.contains(groupKey))
{
continue;
}
priorSeenGroups.add(groupKey);
nextResult = resultSetProcessor.getSelectExprProcessor().process(eventsPerStream, true, true, exprEvaluatorContext);
break;
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
}