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


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, 2005, Oracle. All rights reserved.
22 package oracle.toplink.essentials.internal.parsing;
23
24 import oracle.toplink.essentials.expressions.*;
25
26 /**
27  * INTERNAL
28  * <p><b>Purpose</b>: Represent a '-' in EJBQL
29  * <p><b>Responsibilities</b>:<ul>
30  * <li> Generate the correct expression for a '-'
31  * </ul>
32  * @author Jon Driscoll and Joel Lucuik
33  * @since July 2003
34  */
35 public class MinusNode extends BinaryOperatorNode {
36     public MinusNode() {
37         super();
38     }
39
40     /**
41      * INTERNAL
42      * Validate node and calculates its type.
43      */
44     public void validate(ParseTreeContext context) {
45         super.validate(context);
46         if ((left != null) && (right != null)) {
47             TypeHelper typeHelper = context.getTypeHelper();
48             setType(typeHelper.extendedBinaryNumericPromotion(
49                         left.getType(), right.getType()));
50         }
51     }
52
53     /**
54      * INTERNAL
55      * Generate the expression. The steps are:
56      * 1. Generate the expression for the left node
57      * 2. Add the .subtract to the where clause returned from step 1
58      * 3. Generate the expression for the right side and use it as the parameter for the .subtract()
59      * 4. Return the completed where clause to the caller
60      */
61     public Expression generateExpression(GenerationContext context) {
62         Expression whereClause = getLeft().generateExpression(context);
63         whereClause = ExpressionMath.subtract(whereClause, getRight().generateExpression(context));
64         return whereClause;
65     }
66
67     public boolean isMinusNode() {
68         return true;
69     }
70 }
71
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