001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     * http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.fusesource.hawtdb.api;
018    
019    import java.util.Arrays;
020    import java.util.Comparator;
021    import java.util.List;
022    
023    /**
024     * Interface used to selectively visit the entries in a BTree.
025     *
026     * @param <Key>
027     * @param <Value>
028     * @author <a href="http://hiramchirino.com">Hiram Chirino</a>
029     */
030    public interface IndexVisitor<Key,Value> {
031    
032        /**
033         * Do you want to visit the range of BTree entries between the first and and second key?
034         *
035         * @param first if null indicates the range of values before the second key.
036         * @param second if null indicates the range of values after the first key.
037         * @param comparator the Comparator configured for the index, may be null.
038         *
039         * @return true if you want to visit the values between the first and second key.
040         */
041        boolean isInterestedInKeysBetween(Key first, Key second, Comparator comparator);
042    
043        /**
044         * The keys and values of an index node.
045         *
046         * @param keys
047         * @param comparator the Comparator configured for the index, may be null.
048         * @param values
049         */
050        void visit(List<Key> keys, List<Value> values, Comparator comparator);
051    
052        /**
053         * @return true if the visitor has quenched it's thirst for more results
054         */
055        boolean isSatiated();
056    
057    }