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


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.expressions.*;
25 import oracle.toplink.essentials.internal.expressions.ConstantExpression;
26
27 /**
28  * INTERNAL
29  * <p><b>Purpose</b>: Represent an unary '-' in EJBQL
30  * <p><b>Responsibilities</b>:<ul>
31  * <li> Generate the correct expression for an unary '-'
32  * </ul>
33  */
34 public class UnaryMinus extends Node {
35
36     public UnaryMinus() {
37         super();
38     }
39
40     /**
41      * INTERNAL
42      * Validate node and calculate its type.
43      */
44     public void validate(ParseTreeContext context) {
45         if (left != null) {
46             left.validate(context);
47             setType(left.getType());
48         }
49     }
50
51     /**
52      * INTERNAL
53      */
54     public void validateParameter(ParseTreeContext context, Object JavaDoc contextType) {
55         // delegate to the argument node
56 left.validateParameter(context, contextType);
57     }
58
59     /**
60      * INTERNAL
61      * Generate the expression.
62      */
63     public Expression generateExpression(GenerationContext context) {
64         Expression whereClause = new ConstantExpression(new Integer JavaDoc(0), new ExpressionBuilder());
65         whereClause = ExpressionMath.subtract(whereClause, getLeft().generateExpression(context));
66         return whereClause;
67     }
68
69 }
70
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