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.schema.LdapComparator;
024import org.slf4j.Logger;
025import org.slf4j.LoggerFactory;
026
027
028/**
029 * A class for the bitStringMatch matchingRule (RFC 4517, par. 4.2.1)
030 * 
031 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
032 */
033public class BitStringComparator extends LdapComparator<String>
034{
035    /** The serial version UID */
036    private static final long serialVersionUID = 2L;
037
038    /** A logger for this class */
039    private static final Logger LOG = LoggerFactory.getLogger( BitStringComparator.class );
040
041
042    /**
043     * The BitStringComparator constructor. Its OID is the IntegerOrderingMatch matching
044     * rule OID.
045     */
046    public BitStringComparator( String oid )
047    {
048        super( oid );
049    }
050
051
052    /**
053     * Implementation of the Compare method
054     */
055    public int compare( String bs1, String bs2 )
056    {
057        LOG.debug( "comparing BitString objects '{}' with '{}'", bs1, bs2 );
058
059        // First, shortcut the process by comparing
060        // references. If they are equals, then bs1 and bs2
061        // reference the same object
062        if ( bs1 == bs2 )
063        {
064            return 0;
065        }
066
067        // Then, deal with one of bs1 or bs2 being null
068        // Both can't be null, because then they would
069        // have been caught by the previous test
070        if ( ( bs1 == null ) || ( bs2 == null ) )
071        {
072            return ( bs1 == null ? -1 : 1 );
073        }
074
075        // We have to get rid of 0 from left of each BitString
076        char[] array1 = bs1.toCharArray();
077        char[] array2 = bs2.toCharArray();
078
079        int pos1 = bs1.indexOf( '1' );
080        int pos2 = bs2.indexOf( '1' );
081
082        if ( pos1 == -1 )
083        {
084            if ( pos2 == -1 )
085            {
086                return 0;
087            }
088            else
089            {
090                return -1;
091            }
092        }
093        else if ( pos2 == -1 )
094        {
095            return 1;
096        }
097
098        int length1 = array1.length - pos1;
099        int length2 = array2.length - pos2;
100
101        if ( length1 == length2 )
102        {
103            for ( int i = 0; i < length1; i++ )
104            {
105                int i1 = i + pos1;
106                int i2 = i + pos2;
107
108                if ( array1[i1] < array2[i2] )
109                {
110                    return -1;
111                }
112                else if ( array1[i1] > array2[i2] )
113                {
114                    return 1;
115                }
116            }
117
118            return 0;
119        }
120
121        if ( length1 < length2 )
122        {
123            return -1;
124        }
125        else
126        {
127            return 1;
128        }
129    }
130}