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Java > Open Source Codes > com > quadcap > sql > ValueExpression


1 package com.quadcap.sql;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import java.io.Externalizable JavaDoc;
42 import java.io.IOException JavaDoc;
43 import java.io.ObjectInput JavaDoc;
44 import java.io.ObjectOutput JavaDoc;
45
46 import java.sql.SQLException JavaDoc;
47
48 import com.quadcap.sql.types.Type;
49 import com.quadcap.sql.types.Value;
50
51 /**
52  * Expression yielding a constant value.
53  *
54  * @author Stan Bailes
55  */
56 public class ValueExpression extends Expression implements Externalizable JavaDoc {
57     Value value;
58
59     public ValueExpression() {}
60     
61     public ValueExpression(Value value) {
62     this.value = value;
63     }
64
65     public int rank() { return 0; }
66     public Value getValue(Session session, Cursor cursor) { return value; }
67     public Type getType(Session session, Cursor cursor) throws SQLException JavaDoc {
68         return value.getType();
69     }
70
71     public void invert() {
72     throw new RuntimeException JavaDoc(
73         "invert not implemented for ValueExpression");
74     }
75
76     public void visitSubExpressions(ExpressionVisitor ev) {
77     }
78
79     public void readExternal(ObjectInput JavaDoc in)
80     throws IOException JavaDoc, ClassNotFoundException JavaDoc
81     {
82     value = (Value)in.readObject();
83     }
84     
85     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
86     out.writeObject(value);
87     }
88
89     public String JavaDoc toString() {
90     if (value == null) {
91         return "<null>";
92     } else {
93         return value.toString();
94     }
95     }
96 }
97
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