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Java > Open Source Codes > smallsql > database > IndexDescriptions


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  * IndexDescriptions.java
29  * ---------------
30  * Author: Volker Berlin
31  *
32  * Created on 23.04.2005
33  */
34 package smallsql.database;
35 /**
36  * A typed implementation of Arraylist for IndexDescription.
37  *
38  * @author Volker Berlin
39  *
40  */
41 class IndexDescriptions {
42     private int size;
43     private IndexDescription[] data;
44     
45     
46     IndexDescriptions(){
47         data = new IndexDescription[4];
48     }
49     
50
51     final int size(){
52         return size;
53     }
54     
55
56     final IndexDescription get(int idx){
57         if (idx >= size)
58             throw new IndexOutOfBoundsException JavaDoc("Column index: "+idx+", Size: "+size);
59         return data[idx];
60     }
61     
62     
63     final void add(IndexDescription descr){
64         if(size >= data.length ){
65             resize(size << 1);
66         }
67         data[size++] = descr;
68     }
69     
70     
71     private final void resize(int newSize){
72         IndexDescription[] dataNew = new IndexDescription[newSize];
73         System.arraycopy(data, 0, dataNew, 0, size);
74         data = dataNew;
75     }
76     
77     
78     final IndexDescription findBestMatch(Strings columns){
79         int bestFactor = Integer.MAX_VALUE;
80         int bestIdx = 0;
81         for(int i=0; i<size; i++){
82             int factor = data[i].matchFactor(columns);
83             if(factor == 0)
84                 return data[i];
85             
86             if(factor < bestFactor){
87                 bestFactor = factor;
88                 bestIdx = i;
89             }
90         }
91         if(bestFactor == Integer.MAX_VALUE)
92             return null;
93         else
94             return data[bestIdx];
95     }
96
97
98     /**
99      * Create all the indexes. This means a file for every index is save.
100      * @param database
101      * @param tableView
102      * @see IndexDescription#setTableView
103      */
104     void create(Database database, TableView tableView) throws Exception JavaDoc{
105         for(int i=0; i<size; i++){
106             data[i].create(database, tableView);
107         }
108     }
109
110
111     void drop(Database database) throws Exception JavaDoc {
112         for(int i=0; i<size; i++){
113             data[i].drop(database);
114         }
115     }
116
117
118     void close() throws Exception JavaDoc{
119         for(int i=0; i<size; i++){
120             data[i].close();
121         }
122     }
123 }
124
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