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Java > Open Source Codes > org > xquark > extractor > algebra > DummyTable


1 /*
2  * This file belongs to the XQuark distribution.
3  * Copyright (C) 2003 Universite de Versailles Saint-Quentin.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307.
18  * You can also get it at http://www.gnu.org/licenses/lgpl.html
19  *
20  * For more information on this software, see http://www.xquark.org.
21  */
22
23 package org.xquark.extractor.algebra;
24
25 import java.util.Collections JavaDoc;
26 import java.util.List JavaDoc;
27 import java.util.Set JavaDoc;
28
29 import org.xquark.extractor.common.SqlWrapperException;
30 import org.xquark.extractor.sql.SqlExpression;
31
32 public final class DummyTable extends Expression implements Relation {
33
34
35     private static final String JavaDoc RCSRevision = "$Revision: 1.4 $";
36     private static final String JavaDoc RCSName = "$Name: $";
37
38
39     Set JavaDoc _providedTableInstances = null;
40     
41     public DummyTable() {}
42
43     public Set JavaDoc providedTableInstances() {
44         if (null == _providedTableInstances)
45             _providedTableInstances = Collections.singleton(this);
46         return _providedTableInstances;
47     }
48
49
50     public Set JavaDoc visibleTableInstances() {
51          return null;
52     }
53
54     public AttributeExpression findNonNullAttribute() {
55         return null;
56     }
57     
58     public List JavaDoc getItems() {
59         return null;
60     }
61
62     public List JavaDoc getKeys() {
63         return null;
64     };
65
66     public List JavaDoc nameTest(String JavaDoc name){
67         return null;
68     }
69
70     public List JavaDoc getOperands()
71     {
72         return null;
73     }
74
75     public String JavaDoc pprint ( )
76     {
77         return "DummyTable";
78     }
79
80     public SqlExpression accept (GenSqlVisitor visitor) throws SqlWrapperException
81     {
82         return visitor.visit(this);
83     }
84
85     public void accept (AlgebraVisitor visitor) throws SqlWrapperException
86     {
87         visitor.visit(this);
88     }
89
90     /**
91      * The semantics chosen for equals of algebra nodes is "the same algebra operator
92      * hierarchy referring to the same database objects".
93      * @param o the expression to be compared with this.
94      */
95     public boolean deepEquals(Object JavaDoc o)
96     {
97         return false;
98     }
99 }
100
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