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 TupleCursor<K, V> extends Cursor<Tuple<K, V>>
034    {
035        /**
036         * An alternative to calling before(Tuple) which often may require
037         * wrapping a key in a newly created Tuple object that may be unnecessary.
038         * This method behaves just like before(Tuple) except it advances to just
039         * before the first value of the key.
040         *
041         * @param key the key to advance just before
042         * @throws Exception if there are faults peforming this operation
043         */
044        void beforeKey( K key ) throws Exception;
045    
046    
047        /**
048         * An alternative to calling after(Tuple) which often may require
049         * wrapping a key in a newly created Tuple object that may be unnecessary.
050         * This method behaves just like after(Tuple) except it advances to just
051         * after the last value of the key.
052         *
053         * @param key the key to advance just after the last value
054         * @throws Exception if there are faults peforming this operation
055         */
056        void afterKey( K key ) throws Exception;
057    
058    
059        /**
060         * An alternative to calling before(Tuple) which often may require
061         * wrapping a key and a value in a newly created Tuple object that may be
062         * unnecessary.  This method behaves just like before(Tuple) except it
063         * advances to just before the value of the key which may still be of the
064         * same key.  This method will not be supported if duplicate keys are not
065         * supported.  In this case an UnsupportedOperationException will be
066         * thrown.
067         *
068         * @param key the key of the value to advance just before
069         * @param value the value to advance just before
070         * @throws UnsupportedOperationException if duplicate keys not supporrted
071         * @throws Exception if there are faults peforming this operation
072         */
073        void beforeValue( K key, V value ) throws Exception;
074    
075    
076        /**
077         * An alternative to calling after(Tuple) which often may require
078         * wrapping a key and a value in a newly created Tuple object that may be
079         * unnecessary.  This method behaves just like after(Tuple) except it
080         * advances to just after the value with the specified key.  This method
081         * will not be supported if duplicate keys are not supported.  In this
082         * case an UnsupportedOperationException will be thrown.
083         *
084         * @param key the key of the value to advance just after
085         * @param value the value to advance just after
086         * @throws UnsupportedOperationException if duplicate keys not supporrted
087         * @throws Exception if there are faults peforming this operation
088         */
089        void afterValue( K key, V value ) throws Exception;
090    }