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 *    https://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.i18n.I18n;
026import org.apache.directory.api.ldap.model.schema.LdapComparator;
027import org.slf4j.Logger;
028import org.slf4j.LoggerFactory;
029
030
031/**
032 * A comparator for Strings.
033 * 
034 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
035 */
036public class StringComparator extends LdapComparator<String> implements Serializable
037{
038    /** The serial version UID */
039    private static final long serialVersionUID = 2L;
040
041    /** A logger for this class */
042    private static final Logger LOG = LoggerFactory.getLogger( StringComparator.class );
043
044
045    /**
046     * The StringComparator constructor. Its OID is the StringMatch matching
047     * rule OID.
048     * 
049     * @param oid The Comparator's OID
050     */
051    public StringComparator( String oid )
052    {
053        super( oid );
054    }
055
056
057    /**
058     * {@inheritDoc}
059     */
060    public int compare( String s1, String s2 )
061    {
062        if ( LOG.isDebugEnabled() )
063        {
064            LOG.debug( I18n.msg( I18n.MSG_13749_COMPARING_STRING, s1, s2 ) );
065        }
066
067        if ( s1 == s2 )
068        {
069            return 0;
070        }
071
072        // -------------------------------------------------------------------
073        // Handle some basis cases
074        // -------------------------------------------------------------------
075        if ( s1 == null )
076        {
077            return -1;
078        }
079
080        return s1.compareTo( s2 );
081    }
082}