001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * // Copyright (c) 1998, 2007, Oracle. All rights reserved.
005: *
006: *
007: * The contents of this file are subject to the terms of either the GNU
008: * General Public License Version 2 only ("GPL") or the Common Development
009: * and Distribution License("CDDL") (collectively, the "License"). You
010: * may not use this file except in compliance with the License. You can obtain
011: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
012: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
013: * language governing permissions and limitations under the License.
014: *
015: * When distributing the software, include this License Header Notice in each
016: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
017: * Sun designates this particular file as subject to the "Classpath" exception
018: * as provided by Sun in the GPL Version 2 section of the License file that
019: * accompanied this code. If applicable, add the following below the License
020: * Header, with the fields enclosed by brackets [] replaced by your own
021: * identifying information: "Portions Copyrighted [year]
022: * [name of copyright owner]"
023: *
024: * Contributor(s):
025: *
026: * If you wish your version of this file to be governed by only the CDDL or
027: * only the GPL Version 2, indicate your decision by adding "[Contributor]
028: * elects to include this software in this distribution under the [CDDL or GPL
029: * Version 2] license." If you don't indicate a single choice of license, a
030: * recipient has the option to distribute your version of this file under
031: * either the CDDL, the GPL Version 2 or to extend the choice of license to
032: * its licensees as provided above. However, if you add GPL Version 2 code
033: * and therefore, elected the GPL Version 2 license, then the option applies
034: * only if the new code is made subject to such option by the copyright
035: * holder.
036: */
037: package oracle.toplink.essentials.internal.parsing;
038:
039: /**
040: * INTERNAL
041: * <p><b>Purpose</b>: Superclass for Aggregate Nodes
042: * <p><b>Responsibilities</b>:<ul>
043: * <li> Apply itself to a query correctly
044: * </ul>
045: * @author Jon Driscoll
046: * @since TopLink 5.0
047: */
048:
049: import oracle.toplink.essentials.expressions.Expression;
050:
051: public abstract class AggregateNode extends Node {
052:
053: private boolean distinct = false;
054:
055: /**
056: * INTERNAL
057: */
058: public String resolveAttribute() {
059: Node arg = getLeft();
060: return arg.isDotNode() ? ((DotNode) arg).resolveAttribute()
061: : null;
062: }
063:
064: /**
065: * resolveClass: Answer the class associated with my left node.
066: */
067: public Class resolveClass(GenerationContext context) {
068: return getLeft().resolveClass(context);
069: }
070:
071: /**
072: * INTERNAL
073: * Is this node an Aggregate node
074: */
075: public boolean isAggregateNode() {
076: return true;
077: }
078:
079: /** */
080: public boolean usesDistinct() {
081: return distinct;
082: }
083:
084: /** */
085: public void setDistinct(boolean distinct) {
086: this .distinct = distinct;
087: }
088:
089: /**
090: * INTERNAL
091: * Return a TopLink expression generated using the left node
092: */
093: public Expression generateExpression(GenerationContext context) {
094: String name = getAsString();
095: Expression aggregateExpr = context.expressionFor(name);
096: if (aggregateExpr == null) {
097: Expression arg = getLeft().generateExpression(context);
098: if (usesDistinct()) {
099: arg = arg.distinct();
100: }
101: aggregateExpr = addAggregateExression(arg);
102: context.addExpression(aggregateExpr, name);
103: }
104: return aggregateExpr;
105: }
106:
107: /**
108: * INTERNAL
109: */
110: protected abstract Expression addAggregateExression(Expression expr);
111:
112: }
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