001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.directory.mavibot.btree;
021
022
023import java.io.IOException;
024
025import org.apache.directory.mavibot.btree.exception.EndOfFileExceededException;
026
027
028/**
029 * A Cursor is used to fetch elements in a BTree and is returned by the
030 * @see BTree#browse method. The cursor <strng>must</strong> be closed
031 * when the user is done with it.
032 * <p>
033 *
034 * @param <V> The type for the stored value
035 * 
036 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
037 */
038public interface ValueCursor<V> extends Cursor<V>
039{
040    /**
041     * Find the next key/value
042     * 
043     * @return A Tuple containing the found key and value
044     * @throws IOException 
045     * @throws EndOfFileExceededException 
046     */
047    V next() throws EndOfFileExceededException, IOException;
048
049
050    /**
051     * Find the previous key/value
052     * 
053     * @return A Tuple containing the found key and value
054     * @throws IOException 
055     * @throws EndOfFileExceededException 
056     */
057    V prev() throws EndOfFileExceededException, IOException;
058
059
060    /**
061     * @return The number of elements stored in the cursor
062     */
063    int size();
064}