/**************************************************************************************
* 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.Serializable;
import java.io.StringWriter;
/**
* A single entry in an order-by clause consisting of an expression and order ascending or descending flag.
*/
public class OrderByElement implements Serializable
{
private static final long serialVersionUID = 0L;
private Expression expression;
private boolean descending;
/**
* Ctor.
*/
public OrderByElement() {
}
/**
* Ctor.
* @param expression is the expression to order by
* @param descending true for descending sort, false for ascending sort
*/
public OrderByElement(Expression expression, boolean descending)
{
this.expression = expression;
this.descending = descending;
}
/**
* Returns the order-by value expression.
* @return expression
*/
public Expression getExpression()
{
return expression;
}
/**
* Sets the order-by value expression.
* @param expression provides order-by values
*/
public void setExpression(Expression expression)
{
this.expression = expression;
}
/**
* Returns true for descending sorts for this column, false for ascending sort.
* @return true for descending sort
*/
public boolean isDescending()
{
return descending;
}
/**
* Set to true for descending sorts for this column, false for ascending sort.
* @param descending true for descending sort
*/
public void setDescending(boolean descending)
{
this.descending = descending;
}
/**
* Renders the clause in textual representation.
* @param writer to output to
*/
public void toEPL(StringWriter writer)
{
expression.toEPL(writer, ExpressionPrecedenceEnum.MINIMUM);
if (descending)
{
writer.write(" desc");
}
}
}