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Java > Open Source Codes > org > hsqldb > ResultBase


1 /* Copyright (c) 2001-2005, The HSQL Development Group
2  * All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  * Redistributions of source code must retain the above copyright notice, this
8  * list of conditions and the following disclaimer.
9  *
10  * Redistributions in binary form must reproduce the above copyright notice,
11  * this list of conditions and the following disclaimer in the documentation
12  * and/or other materials provided with the distribution.
13  *
14  * Neither the name of the HSQL Development Group nor the names of its
15  * contributors may be used to endorse or promote products derived from this
16  * software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
22  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
26  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30
31
32 package org.hsqldb;
33
34 /*
35 * This class introduces iterator functionality to Result.
36 *
37 * @author fredt@users
38 * @version 1.7.2
39 * @since 1.7.2
40 */
41 public class ResultBase {
42
43     public Record rRoot;
44     protected Record rTail;
45     protected int iSize;
46
47     public ResultBase() {}
48
49     public ResultIterator iterator() {
50         return new ResultIterator();
51     }
52
53     public class ResultIterator {
54
55         boolean removed;
56         int counter;
57         Record current = rRoot;
58         Record last;
59
60         public boolean hasNext() {
61             return counter < iSize;
62         }
63
64         public boolean next() {
65
66             if (hasNext()) {
67                 removed = false;
68
69                 if (counter != 0) {
70                     last = current;
71                     current = current.next;
72                 }
73
74                 counter++;
75
76                 return true;
77             } else {
78                 return false;
79             }
80         }
81
82         public boolean previous() {
83             return false;
84         }
85
86         public boolean absolute(int rows) {
87             return false;
88         }
89
90         public boolean relative(int rows) {
91             return false;
92         }
93
94         public boolean beforeFirst() {
95             return false;
96         }
97
98         public boolean afterLast() {
99             return false;
100         }
101
102         public boolean isBeforeFirst() {
103             return false;
104         }
105
106         public boolean isAfterLast() {
107             return false;
108         }
109
110         public void remove() {
111
112             if (counter <= iSize && counter != 0 &&!removed) {
113                 removed = true;
114
115                 if (current == rTail) {
116                     rTail = last;
117                 }
118
119                 if (current == rRoot) {
120                     current = rRoot = rRoot.next;
121                 } else {
122                     current = last;
123                     last = null;
124                     current.next = current.next.next;
125                 }
126
127                 iSize--;
128                 counter--;
129
130                 return;
131             }
132         }
133     }
134 }
135
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