/*
* *************************************************************************************
* 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.expression;
import com.espertech.esper.client.EventBean;
import com.espertech.esper.rowregex.RegexExprPreviousEvalStrategy;
import com.espertech.esper.rowregex.RegexPartitionStateRandomAccess;
import com.espertech.esper.util.JavaClassHelper;
/**
* Represents the 'prev' previous event function in match-recognize "define" item.
*/
public class ExprPreviousMatchRecognizeNode extends ExprNodeBase implements ExprEvaluator
{
private static final long serialVersionUID = 0L;
private Class resultType;
private int streamNumber;
private Integer constantIndexNumber;
private transient RegexExprPreviousEvalStrategy strategy;
private transient ExprEvaluator evaluator;
private int assignedIndex;
public void validate(ExprValidationContext validationContext) throws ExprValidationException
{
if (this.getChildNodes().length != 2)
{
throw new ExprValidationException("Match-Recognize Previous expression must have 2 child nodes");
}
if (!(this.getChildNodes()[0] instanceof ExprIdentNode))
{
throw new ExprValidationException("Match-Recognize Previous expression requires an property identifier as the first parameter");
}
if (!this.getChildNodes()[1].isConstantResult() || (!JavaClassHelper.isNumericNonFP(this.getChildNodes()[1].getExprEvaluator().getType())))
{
throw new ExprValidationException("Match-Recognize Previous expression requires an integer index parameter or expression as the second parameter");
}
ExprNode constantNode = this.getChildNodes()[1];
Object value = constantNode.getExprEvaluator().evaluate(null, false, validationContext.getExprEvaluatorContext());
if (!(value instanceof Number))
{
throw new ExprValidationException("Match-Recognize Previous expression requires an integer index parameter or expression as the second parameter");
}
constantIndexNumber = ((Number) value).intValue();
// Determine stream number
ExprIdentNode identNode = (ExprIdentNode) this.getChildNodes()[0];
streamNumber = identNode.getStreamId();
evaluator = this.getChildNodes()[0].getExprEvaluator();
resultType = evaluator.getType();
}
public ExprEvaluator getExprEvaluator()
{
return this;
}
/**
* Returns the index number.
* @return index number
*/
public Integer getConstantIndexNumber()
{
if (constantIndexNumber == null)
{
ExprNode constantNode = this.getChildNodes()[1];
Object value = constantNode.getExprEvaluator().evaluate(null, false, null);
constantIndexNumber = ((Number) value).intValue();
}
return constantIndexNumber;
}
public Class getType()
{
return resultType;
}
public boolean isConstantResult()
{
return false;
}
public Object evaluate(EventBean[] eventsPerStream, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext)
{
RegexPartitionStateRandomAccess access = strategy.getAccess(exprEvaluatorContext);
EventBean substituteEvent = access.getPreviousEvent(assignedIndex);
if (substituteEvent == null)
{
return null;
}
// Substitute original event with prior event, evaluate inner expression
EventBean originalEvent = eventsPerStream[streamNumber];
eventsPerStream[streamNumber] = substituteEvent;
Object evalResult = evaluator.evaluate(eventsPerStream, isNewData, exprEvaluatorContext);
eventsPerStream[streamNumber] = originalEvent;
return evalResult;
}
public String toExpressionString()
{
StringBuilder buffer = new StringBuilder();
buffer.append("prev(");
buffer.append(this.getChildNodes()[0].toExpressionString());
buffer.append(',');
buffer.append(this.getChildNodes()[1].toExpressionString());
buffer.append(')');
return buffer.toString();
}
public boolean equalsNode(ExprNode node)
{
if (!(node instanceof ExprPreviousMatchRecognizeNode))
{
return false;
}
return true;
}
/**
* Sets the index to use when accessing via getter
* @param assignedIndex index
*/
public void setAssignedIndex(int assignedIndex)
{
this.assignedIndex = assignedIndex;
}
public void setStrategy(RegexExprPreviousEvalStrategy strategy) {
this.strategy = strategy;
}
}