1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.directory.mavibot.btree;
21
22
23 import java.io.IOException;
24
25 import org.apache.directory.mavibot.btree.exception.EndOfFileExceededException;
26
27
28 /**
29 * A class that encapsulate the values into an array
30 *
31 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
32 */
33 /* No qualifier */class ValueArrayCursor<V> implements ValueCursor<V>
34 {
35 /** Store the current position in the array or in the BTree */
36 private int currentPos;
37
38 /** The array storing values (1 to N) */
39 private V[] valueArray;
40
41
42 /**
43 * Create an instance
44 */
45 public ValueArrayCursor( V[] valueArray )
46 {
47 // Start at -1 to be positioned before the first element
48 currentPos = BEFORE_FIRST;
49 this.valueArray = valueArray;
50 }
51
52
53 /**
54 * {@inheritDoc}
55 */
56 @Override
57 public boolean hasNext()
58 {
59 return ( currentPos < valueArray.length - 1 ) && ( currentPos != AFTER_LAST );
60 }
61
62
63 /**
64 * {@inheritDoc}
65 */
66 public V next()
67 {
68 if ( valueArray == null )
69 {
70 // Deserialize the array
71 return null;
72 }
73 else
74 {
75 currentPos++;
76
77 if ( currentPos == valueArray.length )
78 {
79 currentPos = AFTER_LAST;
80
81 // We have reached the end of the array
82 return null;
83 }
84 else
85 {
86 return valueArray[currentPos];
87 }
88 }
89 }
90
91
92 /**
93 * {@inheritDoc}
94 */
95 @Override
96 public boolean hasPrev() throws EndOfFileExceededException, IOException
97 {
98 return currentPos > 0 || currentPos == AFTER_LAST;
99 }
100
101
102 /**
103 * {@inheritDoc}
104 */
105 @Override
106 public void close()
107 {
108 }
109
110
111 /**
112 * {@inheritDoc}
113 */
114 @Override
115 public void beforeFirst() throws IOException
116 {
117 currentPos = BEFORE_FIRST;
118 }
119
120
121 /**
122 * {@inheritDoc}
123 */
124 @Override
125 public void afterLast() throws IOException
126 {
127 currentPos = AFTER_LAST;
128 }
129
130
131 /**
132 * {@inheritDoc}
133 */
134 @Override
135 public V prev() throws EndOfFileExceededException, IOException
136 {
137 if ( valueArray == null )
138 {
139 // Deserialize the array
140 return null;
141 }
142 else
143 {
144 if ( currentPos == AFTER_LAST )
145 {
146 currentPos = valueArray.length - 1;
147 }
148 else
149 {
150 currentPos--;
151 }
152
153 if ( currentPos == BEFORE_FIRST )
154 {
155 // We have reached the end of the array
156 return null;
157 }
158 else
159 {
160 return valueArray[currentPos];
161 }
162 }
163 }
164
165
166 /**
167 * {@inheritDoc}
168 */
169 @Override
170 public int size()
171 {
172 return valueArray.length;
173 }
174 }