/**************************************************************************************
* 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.join.exec.base;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.util.IndentWriter;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import java.util.Collection;
import java.util.Set;
/**
* Execution node for lookup in a table for outer joins. This execution node thus generates
* rows even if no joined events could be found, the joined table events are set to null if no
* joined events are found.
*/
public class TableOuterLookupExecNode extends ExecNode
{
private int indexedStream;
private JoinExecTableLookupStrategy lookupStrategy;
/**
* Ctor.
* @param indexedStream - stream indexed for lookup
* @param lookupStrategy - strategy to use for lookup (full table/indexed)
*/
public TableOuterLookupExecNode(int indexedStream, JoinExecTableLookupStrategy lookupStrategy)
{
this.indexedStream = indexedStream;
this.lookupStrategy = lookupStrategy;
}
/**
* Returns strategy for lookup.
* @return lookup strategy
*/
public JoinExecTableLookupStrategy getLookupStrategy()
{
return lookupStrategy;
}
public void process(EventBean lookupEvent, EventBean[] prefillPath, Collection<EventBean[]> result, ExprEvaluatorContext exprEvaluatorContext)
{
// Lookup events
Set<EventBean> joinedEvents = lookupStrategy.lookup(lookupEvent, null, exprEvaluatorContext);
// If no events are found, since this is an outer join, create a result row leaving the
// joined event as null.
if ((joinedEvents == null) || (joinedEvents.isEmpty()))
{
EventBean[] events = new EventBean[prefillPath.length];
System.arraycopy(prefillPath, 0, events, 0, events.length);
result.add(events);
return;
}
// Create result row for each found event
for (EventBean joinedEvent : joinedEvents)
{
EventBean[] events = new EventBean[prefillPath.length];
System.arraycopy(prefillPath, 0, events, 0, events.length);
events[indexedStream] = joinedEvent;
result.add(events);
}
}
/**
* Returns target stream for lookup.
* @return indexed stream
*/
public int getIndexedStream()
{
return indexedStream;
}
public void print(IndentWriter writer)
{
writer.println("TableOuterLookupExecNode indexedStream=" + indexedStream + " lookup=" + lookupStrategy);
}
}