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 /** 020 * Interface used to determine the simple prefix of two keys. Used by BTree indexes 021 * to implement the variable magnitude optimization. 022 * 023 * @author <a href="http://hiramchirino.com">Hiram Chirino</a> 024 */ 025 public interface Prefixer<Key> { 026 027 /** 028 * This methods should return shortest prefix of value2 where the 029 * following still holds:<br/> 030 * value1 <= prefix <= value2.<br/> 031 * <br/> 032 * 033 * When this method is called, the following is guaranteed:<br/> 034 * value1 < value2<br/> 035 * <br/> 036 * 037 * 038 * @param value1 039 * @param value2 040 * @return 041 */ 042 public Key getSimplePrefix(Key value1, Key value2); 043 }