/**************************************************************************************
* 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.client.soda;
import java.io.StringWriter;
/**
* Property-exists checks if a dynamic property exists.
*/
public class PropertyExistsExpression extends ExpressionBase
{
private static final long serialVersionUID = 415089848067641931L;
/**
* Ctor - for use to create an expression tree, without child expression.
*/
public PropertyExistsExpression()
{
}
/**
* Ctor.
* @param propertyName is the name of the property to check existence
*/
public PropertyExistsExpression(String propertyName)
{
this.getChildren().add(Expressions.getPropExpr(propertyName));
}
public ExpressionPrecedenceEnum getPrecedence()
{
return ExpressionPrecedenceEnum.UNARY;
}
public void toPrecedenceFreeEPL(StringWriter writer)
{
writer.write("exists(");
this.getChildren().get(0).toEPL(writer, ExpressionPrecedenceEnum.MINIMUM);
writer.write(")");
}
}