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


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.List JavaDoc;
26 import java.util.Set JavaDoc;
27
28 public abstract class UnaryAlgebra extends UnaryOperator implements Relation
29 {
30
31     private static final String JavaDoc RCSRevision = "$Revision: 1.5 $";
32     private static final String JavaDoc RCSName = "$Name: $";
33
34
35     protected List JavaDoc _keys = null;
36
37     public UnaryAlgebra() {}
38
39     public UnaryAlgebra(Expression operand)
40     {
41         super (operand);
42     }
43
44     public List JavaDoc getParameterList() // TODO: check use
45 {
46         return null;
47     }
48
49     public Set JavaDoc providedTableInstances(){
50         /* default implementation for group, sort, restrict .
51         aggregate project should overide this implementation */
52         return visibleTableInstances();
53     }
54
55     public Set JavaDoc visibleTableInstances() {
56         return ((Relation)getOperand()).providedTableInstances();
57     }
58     
59     public AttributeExpression findNonNullAttribute() {
60         return ((Relation)getOperand()).findNonNullAttribute();
61     }
62
63     public Mapper getMapper() {
64         return _mapper == null ? getOperand().getMapper() : _mapper;
65     }
66
67     abstract public List JavaDoc getKeys();
68
69     public void setKeys(List JavaDoc keys) {
70         _keys = keys;
71     }
72
73
74     public List JavaDoc nameTest(String JavaDoc name)
75     {
76         // this default implementation is for UnOpRestrict,UnOpSort,UnOpGroup,RenameRelation.
77 // UnOpProject, UnOpAggregate should override this function.
78 Relation oprnd = (Relation)getOperand();
79          return oprnd.nameTest(name);
80     }
81 }
82
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