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.shared.ldap.model.schema.comparators; 021 022 023import org.apache.directory.shared.ldap.model.entry.StringValue; 024import org.apache.directory.shared.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 * The CsnComparator constructor. Its OID is the CsnMatch matching 050 * rule OID. 051 */ 052 public CsnComparator( String oid ) 053 { 054 super( oid ); 055 } 056 057 058 /** 059 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object) 060 */ 061 public int compare( Object csnObj1, Object csnObj2 ) 062 { 063 LOG.debug( "comparing CSN objects '{}' with '{}'", csnObj1, csnObj2 ); 064 065 if ( csnObj1 == csnObj2 ) 066 { 067 return 0; 068 } 069 070 // ------------------------------------------------------------------- 071 // Handle some basis cases 072 // ------------------------------------------------------------------- 073 if ( csnObj1 == null ) 074 { 075 return ( csnObj2 == null ) ? 0 : -1; 076 } 077 078 if ( csnObj2 == null ) 079 { 080 return 1; 081 } 082 083 String csnStr1 = null; 084 String csnStr2 = null; 085 086 if ( csnObj1 instanceof StringValue ) 087 { 088 csnStr1 = ( ( StringValue ) csnObj1 ).getValue(); 089 } 090 else 091 { 092 csnStr1 = csnObj1.toString(); 093 } 094 095 if ( csnObj2 instanceof StringValue ) 096 { 097 csnStr2 = ( (StringValue) csnObj2 ).getValue(); 098 } 099 else 100 { 101 csnStr2 = csnObj2.toString(); 102 } 103 104 return csnStr1.compareTo( csnStr2 ); 105 } 106}