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Java > Open Source Codes > oracle > toplink > essentials > internal > parsing > AvgNode


1 /*
2  * The contents of this file are subject to the terms
3  * of the Common Development and Distribution License
4  * (the "License"). You may not use this file except
5  * in compliance with the License.
6  *
7  * You can obtain a copy of the license at
8  * glassfish/bootstrap/legal/CDDLv1.0.txt or
9  * https://glassfish.dev.java.net/public/CDDLv1.0.html.
10  * See the License for the specific language governing
11  * permissions and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL
14  * HEADER in each file and include the License file at
15  * glassfish/bootstrap/legal/CDDLv1.0.txt. If applicable,
16  * add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your
18  * own identifying information: Portions Copyright [yyyy]
19  * [name of copyright owner]
20  */
21 // Copyright (c) 1998, 2006, Oracle. All rights reserved.
22 package oracle.toplink.essentials.internal.parsing;
23
24 import oracle.toplink.essentials.queryframework.ObjectLevelReadQuery;
25 import oracle.toplink.essentials.queryframework.ReportQuery;
26 import oracle.toplink.essentials.expressions.Expression;
27
28 /**
29  * INTERNAL
30  * <p><b>Purpose</b>: Model a AVG
31  * <p><b>Responsibilities</b>:<ul>
32  * <li> Apply itself to a query correctly
33  * </ul>
34  */
35 public class AvgNode extends AggregateNode {
36
37     /**
38      * INTERNAL
39      * Apply this node to the passed query
40      */
41     public void applyToQuery(ObjectLevelReadQuery theQuery, GenerationContext context) {
42         if (theQuery.isReportQuery()) {
43             ReportQuery reportQuery = (ReportQuery)theQuery;
44             reportQuery.addAverage(resolveAttribute(),
45                                    getArgumentExpression(context), Double JavaDoc.class);
46         }
47     }
48
49     /**
50      * INTERNAL
51      * Validate node and calculate its type.
52      */
53     public void validate(ParseTreeContext context) {
54         if (left != null) {
55             left.validate(context);
56         }
57         TypeHelper typeHelper = context.getTypeHelper();
58         setType(typeHelper.getDoubleClassType());
59     }
60
61     /**
62      * INTERNAL
63      * Return a TopLink expression generated using the left node
64      */
65     public Expression generateExpression(GenerationContext context) {
66         return getArgumentExpression(context).average();
67     }
68
69     /**
70      * INTERNAL
71      * Get the string representation of this node.
72      */
73     public String JavaDoc getAsString() {
74         return "AVG(" + left.getAsString() + ")";
75     }
76 }
77
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