/*
***************************************************************************************
* 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.spec;
import com.espertech.esper.epl.expression.core.ExprNode;
import com.espertech.esper.util.MetaDefItem;
import java.io.Serializable;
import java.util.Collection;
/**
* Specification object to an element in the order-by expression.
*/
public class OrderByItem implements MetaDefItem, Serializable {
public static final OrderByItem[] EMPTY_ORDERBY_ARRAY = new OrderByItem[0];
private ExprNode exprNode;
private boolean isDescending;
private static final long serialVersionUID = 4147598689501964350L;
/**
* Ctor.
*
* @param exprNode is the order-by expression node
* @param ascending is true for ascending, or false for descending sort
*/
public OrderByItem(ExprNode exprNode, boolean ascending) {
this.exprNode = exprNode;
isDescending = ascending;
}
/**
* Returns the order-by expression node.
*
* @return expression node.
*/
public ExprNode getExprNode() {
return exprNode;
}
/**
* Returns true for ascending, false for descending.
*
* @return indicator if ascending or descending
*/
public boolean isDescending() {
return isDescending;
}
public OrderByItem copy() {
return new OrderByItem(exprNode, isDescending());
}
public static OrderByItem[] toArray(Collection<OrderByItem> expressions) {
if (expressions.isEmpty()) {
return EMPTY_ORDERBY_ARRAY;
}
return expressions.toArray(new OrderByItem[expressions.size()]);
}
}