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.server.xdbm;
21
22
23 import org.apache.directory.api.ldap.model.cursor.AbstractCursor;
24 import org.apache.directory.api.ldap.model.cursor.CursorException;
25 import org.apache.directory.api.ldap.model.exception.LdapException;
26 import org.apache.directory.server.core.api.partition.PartitionTxn;
27
28
29 /**
30 * An abstract Cursor used by the index cursors.
31 *
32 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
33 */
34 public abstract class AbstractIndexCursor<V> extends AbstractCursor<IndexEntry<V, String>>
35 {
36 /** Tells if there are some element available in the cursor */
37 private boolean available = false;
38
39 /** A transaction associated with this cursor */
40 protected PartitionTxn partitionTxn;
41
42 /** The message used for unsupported operations */
43 protected static final String UNSUPPORTED_MSG = "Unsupported operation";
44
45
46 /**
47 * {@inheritDoc}
48 */
49 public boolean available()
50 {
51 return available;
52 }
53
54
55 /**
56 * Gets the message to return for operations that are not supported
57 *
58 * @return The Unsupported message
59 */
60 protected abstract String getUnsupportedMessage();
61
62
63 /**
64 * {@inheritDoc}
65 */
66 public void after( IndexEntry<V, String> element ) throws LdapException, CursorException
67 {
68 throw new UnsupportedOperationException( getUnsupportedMessage() );
69 }
70
71
72 /**
73 * {@inheritDoc}
74 */
75 public void before( IndexEntry<V, String> element ) throws LdapException, CursorException
76 {
77 throw new UnsupportedOperationException( getUnsupportedMessage() );
78 }
79
80
81 /**
82 * {@inheritDoc}
83 */
84 protected boolean setAvailable( boolean available )
85 {
86 this.available = available;
87 return available;
88 }
89
90
91
92 @Override
93 public boolean previous() throws LdapException, CursorException
94 {
95 return false;
96 }
97
98
99 @Override
100 public boolean next() throws LdapException, CursorException
101 {
102 return false;
103 }
104 }