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.core.partition.impl.btree; 021 022 023 import org.apache.directory.shared.ldap.schema.comparators.SerializableComparator; 024 025 026 /** 027 * TupleComparator for index records. 028 * 029 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 030 * @version $Rev: 539571 $ 031 */ 032 public class ReverseIndexComparator<V> implements TupleComparator<Long, V> 033 { 034 private static final long serialVersionUID = 3257283621751633459L; 035 036 /** The value comparison to use - keys are Longs */ 037 private final SerializableComparator<V> valueComparator; 038 039 040 /** 041 * Creates an IndexComparator. 042 * 043 * @param valueComparator the table comparator to use for values 044 */ 045 public ReverseIndexComparator( SerializableComparator<V> valueComparator ) 046 { 047 this.valueComparator = valueComparator; 048 } 049 050 051 /** 052 * Gets the comparator used to compare keys. 053 * 054 * @return the comparator for comparing keys. 055 */ 056 public SerializableComparator<Long> getKeyComparator() 057 { 058 return LongComparator.INSTANCE; 059 } 060 061 062 /** 063 * Gets the binary comparator used to compare values which are the values 064 * of attributes. 065 * 066 * @return the binary comparator for comparing values. 067 */ 068 public SerializableComparator<V> getValueComparator() 069 { 070 return valueComparator; 071 } 072 073 074 /** 075 * Compares key Object to determine their sorting order returning a 076 * value = to, < or > than 0. 077 * 078 * @param l1 the first long key to compare 079 * @param l2 the other long key to compare to the first 080 * @return 0 if both are equal, a negative value less than 0 if the first 081 * is less than the second, or a postive value if the first is greater than 082 * the second byte array. 083 */ 084 public int compareKey( Long l1, Long l2 ) 085 { 086 return ( l1 < l2 ? -1 : ( l1.equals( l2 ) ? 0 : 1 ) ); 087 } 088 089 090 /** 091 * Comparse value Objects to determine their sorting order returning a 092 * value = to, < or > than 0. 093 * 094 * @param v1 the first value to compare 095 * @param v2 the other value to compare to the first 096 * @return 0 if both are equal, a negative value less than 0 if the first 097 * is less than the second, or a postive value if the first is greater than 098 * the second Object. 099 */ 100 public int compareValue( V v1, V v2 ) 101 { 102 return valueComparator.compare( v1, v2 ); 103 } 104 }