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


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.ArrayList JavaDoc;
26 import java.util.List JavaDoc;
27
28 public class RemoveProjectVoteVisitor extends DefaultSimpleVisitor {
29     private static final String JavaDoc RCSRevision = "$Revision: 1.3 $";
30     private static final String JavaDoc RCSName = "$Name: $";
31
32     private List JavaDoc _opposerList = new ArrayList JavaDoc();
33
34     public RemoveProjectVoteVisitor() {
35     }
36
37     public void reinit() {
38         _opposerList.clear();
39     }
40
41     public List JavaDoc getOpposerList() {
42         return _opposerList;
43     }
44
45     public void visit(FunAggregate arg) {
46         int operator = arg.getOperator();
47         if (FunAggregate.COUNT == operator) {
48             Expression operand = arg.getOperand();
49             if (operand instanceof AttributeExpression) {
50                 if (((AttributeExpression)operand).getAttribute().equals("*")) {
51                     _opposerList.add(arg);
52                 }
53             }
54         }
55     }
56
57     /* the visit will end when enconter a relational algebra node */
58     public void visit(UnaryAlgebra arg) {
59     }
60
61     public void visit(BinaryAlgebra arg) {
62     }
63
64     public void visit(BinOpOuterJoin arg) {
65     }
66
67     public void visit(Join arg) {
68     }
69 }
70
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