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.server.core.partition.impl.btree;
021
022
023import java.util.NoSuchElementException;
024import java.util.regex.Pattern;
025
026import javax.naming.NamingEnumeration;
027import javax.naming.NamingException;
028
029import org.apache.directory.api.ldap.model.cursor.Tuple;
030import org.apache.directory.api.util.exception.NotImplementedException;
031import org.apache.directory.server.xdbm.IndexEntry;
032
033
034/**
035 * A NamingEnumeration over an Index which returns IndexRecords.
036 * 
037 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
038 */
039public class IndexEnumeration<T> implements NamingEnumeration<IndexEntry>
040{
041    /** */
042    private final Pattern re;
043    /** */
044    private final IndexEntry tmp = new IndexEntry();
045    /** */
046    private final IndexEntry returned = new IndexEntry();
047    /** */
048    private final IndexEntry prefetched = new IndexEntry();
049    /** */
050    private final boolean swapKeyVal;
051    /** */
052    private final NamingEnumeration<Tuple> underlying;
053
054    /** */
055    private boolean hasMore = true;
056
057
058    // ------------------------------------------------------------------------
059    // C O N S T R U C T O R S
060    // ------------------------------------------------------------------------
061
062    public IndexEnumeration( NamingEnumeration<Tuple> list ) throws NamingException
063    {
064        this( list, false, null );
065    }
066
067
068    public IndexEnumeration( NamingEnumeration<Tuple> list, boolean swapKeyVal ) throws NamingException
069    {
070        this( list, swapKeyVal, null );
071    }
072
073
074    public IndexEnumeration( NamingEnumeration<Tuple> list, boolean swapKeyVal, Pattern regex ) throws NamingException
075    {
076        re = regex;
077        underlying = list;
078        this.swapKeyVal = swapKeyVal;
079
080        if ( !underlying.hasMore() )
081        {
082            hasMore = false;
083            return;
084        }
085
086        prefetch();
087    }
088
089
090    // ------------------------------------------------------------------------
091    // NamingEnumeration Interface Methods 
092    // ------------------------------------------------------------------------
093
094    /**
095     * @see javax.naming.NamingEnumeration#next()
096     */
097    public IndexEntry next() throws NamingException
098    {
099        returned.copy( prefetched );
100        prefetch();
101        return returned;
102    }
103
104
105    /**
106     * @see java.util.Enumeration#nextElement()
107     */
108    public IndexEntry nextElement()
109    {
110        try
111        {
112            return next();
113        }
114        catch ( NamingException ne )
115        {
116            throw new NoSuchElementException();
117        }
118    }
119
120
121    /**
122     * @see javax.naming.NamingEnumeration#hasMore()
123     */
124    public boolean hasMore()
125    {
126        return hasMore;
127    }
128
129
130    /**
131     * @see javax.naming.NamingEnumeration#hasMoreElements()
132     */
133    public boolean hasMoreElements()
134    {
135        return hasMore;
136    }
137
138
139    /**
140     * @see javax.naming.NamingEnumeration#close()
141     */
142    public void close() throws NamingException
143    {
144        hasMore = false;
145        underlying.close();
146    }
147
148
149    // ------------------------------------------------------------------------
150    // Private Methods 
151    // ------------------------------------------------------------------------
152
153    private void prefetch() throws NamingException
154    {
155        while ( underlying.hasMore() )
156        {
157            Tuple tuple = underlying.next();
158
159            if ( swapKeyVal )
160            {
161                throw new NotImplementedException();
162                // tmp.setSwapped( tuple, null );
163            }
164            else
165            {
166                tmp.setTuple( tuple );
167            }
168
169            // If regex is null just transfer into prefetched from tmp record
170            // but if it is not then use it to match.  Successful match shorts
171            // while loop.
172            if ( null == re || re.matcher( ( String ) tmp.getKey() ).matches() )
173            {
174                prefetched.copy( tmp );
175                return;
176            }
177        }
178
179        // If we got down here then cursor has been consumed without a match!
180        hasMore = false;
181    }
182}