/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* 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.util;
import com.espertech.esper.epl.expression.core.ExprNode;
import com.espertech.esper.epl.expression.visitor.ExprNodeIdentifierCollectVisitor;
import java.util.Set;
public class EligibilityUtil {
public static EligibilityDesc verifyInputStream(ExprNode expression, int indexedStream) {
ExprNodeIdentifierCollectVisitor visitor = new ExprNodeIdentifierCollectVisitor();
expression.accept(visitor);
Set<Integer> inputStreamsRequired = visitor.getStreamsRequired();
if (inputStreamsRequired.size() > 1) { // multi-stream dependency no optimization (i.e. a+b=c)
return new EligibilityDesc(Eligibility.INELIGIBLE, null);
}
if (inputStreamsRequired.size() == 1 && inputStreamsRequired.iterator().next() == indexedStream) { // self-compared no optimization
return new EligibilityDesc(Eligibility.INELIGIBLE, null);
}
if (inputStreamsRequired.isEmpty()) {
return new EligibilityDesc(Eligibility.REQUIRE_NONE, null);
}
return new EligibilityDesc(Eligibility.REQUIRE_ONE, inputStreamsRequired.iterator().next());
}
}