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.shared.ldap.schema.comparators; 021 022 023 import java.util.Comparator; 024 025 import org.apache.directory.shared.i18n.I18n; 026 import org.apache.directory.shared.ldap.schema.LdapComparator; 027 import org.slf4j.Logger; 028 import org.slf4j.LoggerFactory; 029 030 031 /** 032 * Compares two objects taking into account that one might be a Comparable. 033 * 034 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 035 * @version $Rev: 912436 $ 036 */ 037 public class ComparableComparator<T> extends LdapComparator<Comparable<T>> 038 { 039 /** A logger for this class */ 040 private static final Logger LOG = LoggerFactory.getLogger( ComparableComparator.class ); 041 042 /** The serialVersionUID */ 043 private static final long serialVersionUID = 1L; 044 045 /** 046 * The BooleanComparator constructor. Its OID is the BooleanMatch matching 047 * rule OID. 048 */ 049 public ComparableComparator( String oid ) 050 { 051 super( oid ); 052 } 053 054 /** 055 * Compares two objects taking into account that one may be a Comparable. If 056 * the first is a comparable then its compareTo operation is called and the 057 * result returned as is. If the first is not a Comparable but the second is 058 * then its compareTo method is called and the result is returned after 059 * being negated. If none are comparables the hashCode of o1 minus the 060 * hashCode of o2 is returned. 061 * 062 * @see Comparator#compare(Object, Object) 063 */ 064 public int compare( Comparable<T> o1, Comparable<T> o2 ) 065 { 066 LOG.debug( "comparing objects '{}' with '{}'", o1, o2 ); 067 068 if ( ( o1 == null ) && ( o2 == null ) ) 069 { 070 return 0; 071 } 072 073 if ( o1 instanceof Comparable<?> ) 074 { 075 if ( o2 == null ) 076 { 077 return -1; 078 } 079 else 080 { 081 return o1.compareTo( ( T ) o2 ); 082 } 083 } 084 085 if ( o2 == null ) 086 { 087 return 1; 088 } 089 else if ( o2 instanceof Comparable<?> ) 090 { 091 if ( o1 == null ) 092 { 093 return -1; 094 } 095 else 096 { 097 return - o2.compareTo( ( T ) o1 ); 098 } 099 } 100 101 // before https://issues.apache.org/jira/browse/DIRSERVER-928 it was 102 // return o1.hashCode() - o2.hashCode(); 103 104 // now we will blow a stack trace if none of the objects are Comparable 105 throw new IllegalArgumentException( I18n.err( I18n.ERR_04217, o1, o2 ) ); 106 } 107 }