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Java > Open Source Codes > org > objectweb > medor > query > lib > Project


1 /**
2  * MEDOR: Middleware Enabling Distributed Object Requests
3  *
4  * Copyright (C) 2001-2004 France Telecom R&D
5  * Contact: alexandre.lefebvre@rd.francetelecom.com
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * This library is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this library; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  *
21  * Initial developers: M. Alia, A. Lefebvre
22  */
23 package org.objectweb.medor.query.lib;
24
25 import org.objectweb.medor.api.Field;
26 import org.objectweb.medor.api.MedorException;
27 import org.objectweb.medor.expression.api.Expression;
28 import org.objectweb.medor.query.api.OperationType;
29 import org.objectweb.medor.query.api.QueryTree;
30 import org.objectweb.medor.query.api.QueryTreeField;
31
32 public class Project extends BasicQueryNode {
33
34     public Project() {
35     }
36
37     /**
38      * Basic constructor. The Fields must be added later.
39      */
40     public Project(String JavaDoc name) {
41         super(name);
42     }
43
44     /**
45      * Constructs a Project node from an array of fieldNames to be projected
46      * from a given (child) QueryTree.
47      * @param fieldNames is the array of field names for which the Field is to
48      * be projected.
49      * @param child is the child QueryTree on which the projection operates.
50      */
51     public Project(String JavaDoc[] fieldNames, QueryTree child, String JavaDoc nodeName)
52             throws MedorException {
53         super(nodeName);
54         for (int i = 0; i < fieldNames.length; i++) {
55             Field f = child.getTupleStructure().getField(fieldNames[i]);
56             QueryTreeField[] anc = new QueryTreeField[1];
57             anc[0] = (QueryTreeField) f;
58             addPropagatedField(f.getName(), f.getType(), anc);
59         }
60     }
61
62     public short getType() {
63         return OperationType.PROJECT;
64     }
65
66     public void setQueryFilter(Expression e) {
67         throw new UnsupportedOperationException JavaDoc("Projections cannot be assigned a filter.");
68     }
69 }
70
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