/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.jpa.parsing;
/**
* INTERNAL
* <p><b>Purpose</b>: Superclass for Aggregate Nodes
* <p><b>Responsibilities</b>:<ul>
* <li> Apply itself to a query correctly
* </ul>
* @author Jon Driscoll
* @since TopLink 5.0
*/
import org.eclipse.persistence.expressions.Expression;
public abstract class AggregateNode extends Node implements AliasableNode {
private boolean distinct = false;
private String alias = null;
/**
* INTERNAL
*/
public String resolveAttribute() {
Node arg = getLeft();
return arg.isDotNode() ? ((DotNode)arg).resolveAttribute() : null;
}
/**
* resolveClass: Answer the class associated with my left node.
*/
public Class resolveClass(GenerationContext context) {
return getLeft().resolveClass(context);
}
/**
* INTERNAL
* Is this node an Aggregate node
*/
public boolean isAggregateNode() {
return true;
}
/** */
public boolean usesDistinct() {
return distinct;
}
/** */
public void setDistinct(boolean distinct) {
this.distinct = distinct;
}
/**
* INTERNAL
* Return a EclipseLink expression generated using the left node
*/
public Expression generateExpression(GenerationContext context) {
if (alias == null){
alias = getAsString();
}
Expression aggregateExpr = context.expressionFor(alias);
if (aggregateExpr == null) {
Expression arg = getLeft().generateExpression(context);
if (usesDistinct()) {
arg = arg.distinct();
}
aggregateExpr = addAggregateExression(arg);
context.addExpression(aggregateExpr, alias);
}
return aggregateExpr;
}
/**
* INTERNAL
*/
protected abstract Expression addAggregateExression(Expression expr);
public String getAlias(){
return this.alias;
}
public void setAlias(String alias){
this.alias = alias;
}
public boolean isAliasableNode(){
return true;
}
}