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


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
25 // TopLink imports
26 import oracle.toplink.essentials.expressions.*;
27
28 /**
29  * INTERNAL
30  * <p><b>Purpose</b>: Used for the EMPTY collection handling
31  * <p><b>Responsibilities</b>:<ul>
32  * <li> Generate the correct expression for an IS EMPTY in EJBQL
33  * </ul>
34  * @author Jon Driscoll and Joel Lucuik
35  * @since August 2003
36  */
37 public class EmptyCollectionComparisonNode extends SimpleConditionalExpressionNode {
38     public boolean notIndicated = false;
39
40     /**
41      * EmptyCollectionComparisonNode constructor comment.
42      */
43     public EmptyCollectionComparisonNode() {
44         super();
45     }
46
47     /**
48      * INTERNAL
49      * Validate node and calculate its type.
50      */
51     public void validate(ParseTreeContext context) {
52         if (left != null) {
53             left.validate(context);
54         }
55         TypeHelper typeHelper = context.getTypeHelper();
56         setType(typeHelper.getBooleanType());
57     }
58
59     /**
60      * INTERNAL
61      * Return a TopLink expression for this node.
62      */
63     public Expression generateExpression(GenerationContext context) {
64         //get the variable name from the DotNode's right attribute
65 //...WHERE emp.firstName IS EMPTY
66 String JavaDoc emptyAttributeName = ((AttributeNode)getLeft().getRight()).getAttributeName();
67         Expression whereClause = getLeft().getLeft().generateExpression(context);
68         if (notIndicated) {
69             return whereClause.notEmpty(emptyAttributeName);
70         } else {
71             return whereClause.isEmpty(emptyAttributeName);
72         }
73     }
74
75     /**
76      * INTERNAL
77      * Indicate if a NOT was found in the WHERE clause.
78      * Examples:
79      * ...WHERE emp.phoneNumbers IS NOT EMPTY
80      */
81     public void indicateNot() {
82         notIndicated = true;
83     }
84
85 }
86
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