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.server.core.cursor.Cursor;
24
25
26 /**
27 * A Cursor introducing new advance methods designed to reduce some
28 * inefficiencies encountered when scanning over Tuples.
29 *
30 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
31 * @version $$Rev$$
32 */
33 public interface TupleCursor<K,V> extends Cursor<Tuple<K,V>>
34 {
35 /**
36 * An alternative to calling before(Tuple) which often may require
37 * wrapping a key in a newly created Tuple object that may be unnecessary.
38 * This method behaves just like before(Tuple) except it advances to just
39 * before the first value of the key.
40 *
41 * @param key the key to advance just before
42 * @throws Exception if there are faults peforming this operation
43 */
44 void beforeKey( K key ) throws Exception;
45
46
47 /**
48 * An alternative to calling after(Tuple) which often may require
49 * wrapping a key in a newly created Tuple object that may be unnecessary.
50 * This method behaves just like after(Tuple) except it advances to just
51 * after the last value of the key.
52 *
53 * @param key the key to advance just after the last value
54 * @throws Exception if there are faults peforming this operation
55 */
56 void afterKey( K key ) throws Exception;
57
58
59 /**
60 * An alternative to calling before(Tuple) which often may require
61 * wrapping a key and a value in a newly created Tuple object that may be
62 * unnecessary. This method behaves just like before(Tuple) except it
63 * advances to just before the value of the key which may still be of the
64 * same key. This method will not be supported if duplicate keys are not
65 * supported. In this case an UnsupportedOperationException will be
66 * thrown.
67 *
68 * @param key the key of the value to advance just before
69 * @param value the value to advance just before
70 * @throws UnsupportedOperationException if duplicate keys not supporrted
71 * @throws Exception if there are faults peforming this operation
72 */
73 void beforeValue( K key, V value ) throws Exception;
74
75
76 /**
77 * An alternative to calling after(Tuple) which often may require
78 * wrapping a key and a value in a newly created Tuple object that may be
79 * unnecessary. This method behaves just like after(Tuple) except it
80 * advances to just after the value with the specified key. This method
81 * will not be supported if duplicate keys are not supported. In this
82 * case an UnsupportedOperationException will be thrown.
83 *
84 * @param key the key of the value to advance just after
85 * @param value the value to advance just after
86 * @throws UnsupportedOperationException if duplicate keys not supporrted
87 * @throws Exception if there are faults peforming this operation
88 */
89 void afterValue( K key, V value ) throws Exception;
90 }