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     */
020    package org.apache.directory.server.xdbm;
021    
022    
023    import org.apache.directory.shared.ldap.cursor.Cursor;
024    
025    
026    /**
027     * A Cursor introducing new advance methods designed to reduce some
028     * inefficiencies encountered when scanning over Tuples.
029     *
030     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
031     * @version $Rev$
032     */
033    public interface IndexCursor<V, E, ID> extends Cursor<IndexEntry<V, E, ID>>
034    {
035        /**
036         * An alternative to calling before(IndexEntry) which often may require
037         * wrapping an id and value in a newly created IndexEntry object that may
038         * be an unnecessary object creation.  Some implementations may not
039         * support this operation and may throw an UnsupportedOperationEception.
040         *
041         * @param id the id for the entry
042         * @param indexValue the value to advance just before
043         * @throws Exception if there are faults performing this operation
044         */
045        void beforeValue( ID id, V indexValue ) throws Exception;
046    
047    
048        /**
049         * An alternative to calling after(IndexEntry) which often may require
050         * wrapping an id and value in a newly created IndexEntry object that may
051         * be an unnecessary object creation.  Some implementations may not
052         * support this operation and may throw an UnsupportedOperationEception.
053         *
054         * @param id the id for the entry
055         * @param indexValue the value to advance just after the last value
056         * @throws Exception if there are faults performing this operation
057         */
058        void afterValue( ID id, V indexValue ) throws Exception;
059    }