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Java > Open Source Codes > org > apache > ojb > jdo > jdoql > NullLiteral


1 package org.apache.ojb.jdo.jdoql;
2
3 /* Copyright 2003-2005 The Apache Software Foundation
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 /**
19  * The 'null' literal.
20  *
21  * @author <a HREF="mailto:tomdz@apache.org">Thomas Dudziak</a>
22  */
23 public class NullLiteral extends Expression
24 {
25     /** The type of this null literal */
26     private Class JavaDoc _type = Object JavaDoc.class;
27
28     /**
29      * Creates a new null literal object.
30      */
31     public NullLiteral()
32     {
33     }
34
35     /* (non-Javadoc)
36      * @see org.apache.ojb.jdo.jdoql.Acceptor#accept(org.apache.ojb.jdo.jdoql.Visitor)
37      */
38     public void accept(Visitor visitor)
39     {
40         visitor.visit(this);
41     }
42
43     /* (non-Javadoc)
44      * @see java.lang.Object#toString()
45      */
46     public String JavaDoc toString()
47     {
48         return "null";
49     }
50
51     /**
52      * Sets the type of this null literal. The type depends on the context
53      * of the literal, e.g. in a binary expression where the other side
54      * is of type string, this literal would also have type string.
55      *
56      * @param type The type
57      */
58     public void setType(Class JavaDoc type)
59     {
60         _type = type;
61     }
62
63     /* (non-Javadoc)
64      * @see org.apache.ojb.jdo.jdoql.Expression#getType()
65      */
66     public Class JavaDoc getType()
67     {
68         return _type;
69     }
70 }
71
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