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Java > Open Source Codes > smallsql > database > IndexNodeScrollStatus


1 /* =============================================================
2  * SmallSQL : a free Java DBMS library for the Java(tm) platform
3  * =============================================================
4  *
5  * (C) Copyright 2004-2006, by Volker Berlin.
6  *
7  * Project Info: http://www.smallsql.de/
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------
28  * IndexNodeScrollStatus.java
29  * ---------------
30  * Author: Volker Berlin
31  *
32  * Created on 26.02.2005
33  */
34 package smallsql.database;
35
36 /**
37  * @author Volker Berlin
38  */
39 final class IndexNodeScrollStatus {
40     final boolean asc;
41     final IndexNode[] nodes;
42     /**
43      * A pointer of the last returns RowOffset. It can be the follow values.
44      * -2; No Value, Before
45      * -1; The Value
46      * 0 to nodes.length-1; Any node from the array nodes.
47      * nodes.length; After the last valid node.
48      */
49     int idx;
50     final Object JavaDoc nodeValue;
51     /**
52      * The current column of the ORDER BY clause. It is starting on 0.
53      */
54     final int level;
55     
56     
57     IndexNodeScrollStatus(IndexNode node, boolean asc, boolean scroll, int level){
58         this.nodes = node.getChildNodes();
59         nodeValue = node.getValue();
60         this.asc = asc;
61         this.idx = (asc ^ scroll) ? nodes.length : -2;
62         this.level = level;
63     }
64     
65     
66     void afterLast(){
67         idx = (asc) ? nodes.length : -2;
68     }
69 }
70
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