/**************************************************************************************
* 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.plan;
import com.espertech.esper.epl.expression.ExprIdentNode;
import com.espertech.esper.epl.spec.OuterJoinDesc;
import java.util.List;
/**
* Analyzes an outer join descriptor list and builds a query graph model from it.
* The 'on' expression identifiers are extracted
* and placed in the query graph model as navigable relationships (by key and index
* properties) between streams.
*/
public class OuterJoinAnalyzer
{
/**
* Analyzes the outer join descriptor list to build a query graph model.
* @param outerJoinDescList - list of outer join descriptors
* @param queryGraph - model containing relationships between streams that is written into
* @return queryGraph object
*/
public static QueryGraph analyze(List<OuterJoinDesc> outerJoinDescList, QueryGraph queryGraph)
{
for (OuterJoinDesc outerJoinDesc : outerJoinDescList)
{
// add optional on-expressions
if (outerJoinDesc.getOptLeftNode() != null) {
ExprIdentNode identNodeLeft = outerJoinDesc.getOptLeftNode();
ExprIdentNode identNodeRight = outerJoinDesc.getOptRightNode();
add(queryGraph, identNodeLeft, identNodeRight);
if (outerJoinDesc.getAdditionalLeftNodes() != null)
{
for (int i = 0; i < outerJoinDesc.getAdditionalLeftNodes().length; i++)
{
add(queryGraph, outerJoinDesc.getAdditionalLeftNodes()[i], outerJoinDesc.getAdditionalRightNodes()[i]);
}
}
}
else {
}
}
return queryGraph;
}
private static void add(QueryGraph queryGraph, ExprIdentNode identNodeLeft, ExprIdentNode identNodeRight)
{
queryGraph.addStrictEquals(identNodeLeft.getStreamId(), identNodeLeft.getResolvedPropertyName(), identNodeLeft,
identNodeRight.getStreamId(), identNodeRight.getResolvedPropertyName(), identNodeRight);
}
}