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 java.io.Serializable;
024
025import org.apache.directory.api.ldap.model.schema.LdapComparator;
026import org.slf4j.Logger;
027import org.slf4j.LoggerFactory;
028
029
030/**
031 * A comparator for Strings.
032 * 
033 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
034 */
035public class StringComparator extends LdapComparator<String> implements Serializable
036{
037    /** The serial version UID */
038    private static final long serialVersionUID = 2L;
039
040    /** A logger for this class */
041    private static final Logger LOG = LoggerFactory.getLogger( StringComparator.class );
042
043
044    /**
045     * The StringComparator constructor. Its OID is the StringMatch matching
046     * rule OID.
047     * 
048     * @param oid The Comparator's OID
049     */
050    public StringComparator( String oid )
051    {
052        super( oid );
053    }
054
055
056    /**
057     * {@inheritDoc}
058     */
059    public int compare( String s1, String s2 )
060    {
061        LOG.debug( "comparing String objects '{}' with '{}'", s1, s2 );
062
063        if ( s1 == s2 )
064        {
065            return 0;
066        }
067
068        // -------------------------------------------------------------------
069        // Handle some basis cases
070        // -------------------------------------------------------------------
071        if ( s1 == null )
072        {
073            return -1;
074        }
075
076        if ( s2 == null )
077        {
078            return 1;
079        }
080
081        return s1.compareTo( s2 );
082    }
083}