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package oracle.toplink.essentials.internal.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 oracle.toplink.essentials.expressions.Expression;
public abstract class AggregateNode extends Node {
private boolean distinct = false;
/**
* 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 TopLink expression generated using the left node
*/
public Expression generateExpression(GenerationContext context) {
String name = getAsString();
Expression aggregateExpr = context.expressionFor(name);
if (aggregateExpr == null) {
Expression arg = getLeft().generateExpression(context);
if (usesDistinct()) {
arg = arg.distinct();
}
aggregateExpr = addAggregateExression(arg);
context.addExpression(aggregateExpr, name);
}
return aggregateExpr;
}
/**
* INTERNAL
*/
protected abstract Expression addAggregateExression(Expression expr);
}