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Java > Open Source Codes > org > objectweb > medor > query > api > QueryTree


1 /**
2  * MEDOR: Middleware Enabling Distributed Object Requests
3  *
4  * Copyright (C) 2001-2003 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
24 package org.objectweb.medor.query.api;
25
26 import org.objectweb.medor.api.TupleStructure;
27 import org.objectweb.medor.api.MedorException;
28 import org.objectweb.medor.clone.api.Cloneable;
29
30 /**
31  *
32  * @author Sebastien Chassande-Barrioz
33  */
34 public interface QueryTree extends Cloneable JavaDoc {
35
36     /**
37      * Returns the TupleStructure associated to the QueryTree.
38      * Note that the Fields cannot be added by manipulating the TupleStructure,
39      * but by using either constructors in the case of a QueryLeaf, or by
40      * using the addXXXFields methods in the case of QueryNodes.
41      */
42     TupleStructure getTupleStructure();
43
44     /**
45      * It returns the name of the query tree.
46      */
47     String JavaDoc getName();
48
49     /**
50      * Tests whether the results should be distinct or not.
51      * @return true if there results should be distinct, false otherwise.
52      */
53     boolean getDistinct();
54
55     /**
56      * Indicates whether evaluating the QueryTree should return unique results
57      * (duplicate elimination) or not.
58      * <p>The default should be that duplicates are not eliminated (distinct
59      * is false).
60      * @param distinct is true if duplicates should be eliminated, false
61      * otherwise.
62      * @throws MedorException if the distinct operation is not supported.
63      */
64     void setDistinct(boolean distinct) throws MedorException;
65
66     /**
67      * Sets the OrderBy array of OrderFields.
68      * <p>This array indicates the fields by which the results should be
69      * ordered.
70      * <p>Like for filters assigned to QueryNodes, the Fields used for ordering
71      * must belong to children of the current QueryTree.
72      * <p>A noticeable exception is the case of RdbExpQueryLeaves, where
73      * ordering fields are fields of the QueryLeaf itself.
74      * @param orders the array of OrderFields indicating the ordering in which
75      * the result should be returned.
76      * @throws MedorException if ordering is not supported.
77      */
78     void setOrderBy(OrderField[] orders) throws MedorException;
79
80     /**
81      * Returns the array of OrderFields indicating how the result should be
82      * ordered.
83      * @return the array of OrderFields.
84      */
85     OrderField[] getOrderBy();
86 }
87
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