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.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     * The BitStringComparator constructor. Its OID is the IntegerOrderingMatch matching
043     * rule OID.
044     */
045    public BitStringComparator( String oid )
046    {
047        super( oid );
048    }
049
050
051    /**
052     * Implementation of the Compare method
053     */
054    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "ES_COMPARING_PARAMETER_STRING_WITH_EQ",
055                justification ="false positive")
056    public int compare( String bs1, String bs2 )
057    {
058        LOG.debug( "comparing BitString objects '{}' with '{}'", bs1, bs2 );
059
060        // First, shortcut the process by comparing
061        // references. If they are equals, then bs1 and bs2
062        // reference the same object
063        if ( bs1 == bs2 )
064        {
065            return 0;
066        }
067
068        // Then, deal with one of bs1 or bs2 being null
069        // Both can't be null, because then they would 
070        // have been caught by the previous test
071        if ( ( bs1 == null ) || ( bs2 == null ) )
072        {
073            return ( bs1 == null ? -1 : 1 );
074        }
075
076        // We have to get rid of 0 from left of each BitString
077        char[] array1 = bs1.toCharArray();
078        char[] array2 = bs2.toCharArray();
079
080        int pos1 = bs1.indexOf( '1' );
081        int pos2 = bs2.indexOf( '1' );
082
083        if ( pos1 == -1 )
084        {
085            if ( pos2 == -1 )
086            {
087                return 0;
088            }
089            else
090            {
091                return -1;
092            }
093        }
094        else if ( pos2 == -1 )
095        {
096            return 1;
097        }
098
099        int length1 = array1.length - pos1;
100        int length2 = array2.length - pos2;
101
102        if ( length1 == length2 )
103        {
104            for ( int i = 0; i < length1; i++ )
105            {
106                int i1 = i + pos1;
107                int i2 = i + pos2;
108
109                if ( array1[i1] < array2[i2] )
110                {
111                    return -1;
112                }
113                else if ( array1[i1] > array2[i2] )
114                {
115                    return 1;
116                }
117            }
118
119            return 0;
120        }
121
122        if ( length1 < length2 )
123        {
124            return -1;
125        }
126        else
127        {
128            return 1;
129        }
130    }
131}