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 */ 020package org.apache.directory.api.ldap.model.schema.comparators; 021 022 023import org.apache.directory.api.ldap.model.entry.StringValue; 024import org.apache.directory.api.ldap.model.schema.LdapComparator; 025import org.slf4j.Logger; 026import org.slf4j.LoggerFactory; 027 028 029/** 030 * A comparator for CSN. 031 * 032 * The CSN are ordered depending on an evaluation of its component, in this order : 033 * - time, 034 * - changeCount, 035 * - sid 036 * - modifierNumber 037 * 038 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 039 */ 040public class CsnComparator extends LdapComparator<Object> 041{ 042 /** The serial version UID */ 043 private static final long serialVersionUID = 2L; 044 045 /** A logger for this class */ 046 private static final Logger LOG = LoggerFactory.getLogger( CsnComparator.class ); 047 048 049 /** 050 * The CsnComparator constructor. Its OID is the CsnMatch matching 051 * rule OID. 052 */ 053 public CsnComparator( String oid ) 054 { 055 super( oid ); 056 } 057 058 059 /** 060 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object) 061 */ 062 public int compare( Object csnObj1, Object csnObj2 ) 063 { 064 LOG.debug( "comparing CSN objects '{}' with '{}'", csnObj1, csnObj2 ); 065 066 if ( csnObj1 == csnObj2 ) 067 { 068 return 0; 069 } 070 071 // ------------------------------------------------------------------- 072 // Handle some basis cases 073 // ------------------------------------------------------------------- 074 if ( csnObj1 == null ) 075 { 076 return ( csnObj2 == null ) ? 0 : -1; 077 } 078 079 if ( csnObj2 == null ) 080 { 081 return 1; 082 } 083 084 String csnStr1 = null; 085 String csnStr2 = null; 086 087 if ( csnObj1 instanceof StringValue ) 088 { 089 csnStr1 = ( ( StringValue ) csnObj1 ).getValue(); 090 } 091 else 092 { 093 csnStr1 = csnObj1.toString(); 094 } 095 096 if ( csnObj2 instanceof StringValue ) 097 { 098 csnStr2 = ( ( StringValue ) csnObj2 ).getValue(); 099 } 100 else 101 { 102 csnStr2 = csnObj2.toString(); 103 } 104 105 return csnStr1.compareTo( csnStr2 ); 106 } 107}