/*
***************************************************************************************
* 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.client.soda;
import java.io.StringWriter;
/**
* Expression representing the prior function.
*/
public class PriorExpression extends ExpressionBase {
private static final long serialVersionUID = 3914409812498086994L;
/**
* Ctor - for use to create an expression tree, without child expression.
*/
public PriorExpression() {
}
/**
* Ctor.
*
* @param index is the index of the prior event
* @param propertyName is the property to return
*/
public PriorExpression(int index, String propertyName) {
this.addChild(new ConstantExpression(index));
this.addChild(new PropertyValueExpression(propertyName));
}
public ExpressionPrecedenceEnum getPrecedence() {
return ExpressionPrecedenceEnum.UNARY;
}
public void toPrecedenceFreeEPL(StringWriter writer) {
writer.write("prior(");
this.getChildren().get(0).toEPL(writer, ExpressionPrecedenceEnum.MINIMUM);
writer.write(",");
this.getChildren().get(1).toEPL(writer, ExpressionPrecedenceEnum.MINIMUM);
writer.write(')');
}
}