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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 Cursor is used to fetch elements in a BTree and is returned by the
30   * @see BTree#browse method. The cursor <strng>must</strong> be closed
31   * when the user is done with it.
32   * <p>
33   *
34   * @param <K> The type for the Key
35   * @param <V> The type for the stored value
36   * 
37   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
38   */
39  public interface TupleCursor<K, V> extends Cursor<K>
40  {
41      /**
42       * Find the next key/value
43       * 
44       * @return A Tuple containing the found key and value
45       * @throws IOException 
46       * @throws EndOfFileExceededException 
47       */
48      Tuple<K, V> next() throws EndOfFileExceededException, IOException;
49  
50  
51      /**
52       * Find the previous key/value
53       * 
54       * @return A Tuple containing the found key and value
55       * @throws IOException 
56       * @throws EndOfFileExceededException 
57       */
58      Tuple<K, V> prev() throws EndOfFileExceededException, IOException;
59  
60  
61      /**
62       * @return The revision this cursor is based on
63       */
64      long getRevision();
65  
66  
67      /**
68       * @return The creation date for this cursor
69       */
70      long getCreationDate();
71  
72  
73      /**
74       * Moves the cursor to the next non-duplicate key.
75  
76       * If the BTree contains 
77       * 
78       *  <ul>
79       *    <li><1,0></li>
80       *    <li><1,1></li>
81       *    <li><2,0></li>
82       *    <li><2,1></li>
83       *  </ul>
84       *   
85       *  and cursor is present at <1,0> then the cursor will move to <2,0>
86       *  
87       * @throws EndOfFileExceededException
88       * @throws IOException
89       */
90      void moveToNextNonDuplicateKey() throws EndOfFileExceededException, IOException;
91  
92  
93      /**
94       * Moves the cursor to the previous non-duplicate key
95       * If the BTree contains 
96       * 
97       *  <ul>
98       *    <li><1,0></li>
99       *    <li><1,1></li>
100      *    <li><2,0></li>
101      *    <li><2,1></li>
102      *  </ul>
103      *   
104      *  and cursor is present at <2,1> then the cursor will move to <1,1>
105      * 
106      * @throws EndOfFileExceededException
107      * @throws IOException
108      */
109     void moveToPrevNonDuplicateKey() throws EndOfFileExceededException, IOException;
110 }