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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.directory.server.core.partition.impl.btree;
21  
22  
23  import org.apache.directory.shared.ldap.NotImplementedException;
24  import org.apache.directory.server.xdbm.ForwardIndexEntry;
25  import org.apache.directory.server.xdbm.IndexEntry;
26  import org.apache.directory.server.xdbm.Tuple;
27  
28  import java.util.NoSuchElementException;
29  import java.util.regex.Pattern;
30  
31  import javax.naming.NamingEnumeration;
32  import javax.naming.NamingException;
33  
34  
35  /**
36   * A NamingEnumeration over an Index which returns IndexRecords.
37   * 
38   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
39   * @version $Rev: 640657 $
40   */
41  public class IndexEnumeration<T> implements NamingEnumeration<IndexEntry>
42  {
43      /** */
44      private final Pattern re;
45      /** */
46      private final ForwardIndexEntry tmp = new ForwardIndexEntry();
47      /** */
48      private final ForwardIndexEntry returned = new ForwardIndexEntry();
49      /** */
50      private final ForwardIndexEntry prefetched = new ForwardIndexEntry();
51      /** */
52      private final boolean swapKeyVal;
53      /** */
54      private final NamingEnumeration<Tuple> underlying;
55  
56      /** */
57      private boolean hasMore = true;
58  
59  
60      // ------------------------------------------------------------------------
61      // C O N S T R U C T O R S
62      // ------------------------------------------------------------------------
63  
64      
65      public IndexEnumeration( NamingEnumeration<Tuple> list ) throws NamingException
66      {
67          this( list, false, null );
68      }
69  
70  
71      public IndexEnumeration( NamingEnumeration<Tuple> list, boolean swapKeyVal ) throws NamingException
72      {
73          this( list, swapKeyVal, null );
74      }
75  
76  
77      public IndexEnumeration( NamingEnumeration<Tuple> list, boolean swapKeyVal, Pattern regex ) 
78          throws NamingException
79      {
80          re = regex;
81          underlying = list;
82          this.swapKeyVal = swapKeyVal;
83  
84          if ( !underlying.hasMore() )
85          {
86              hasMore = false;
87              return;
88          }
89  
90          prefetch();
91      }
92  
93  
94      // ------------------------------------------------------------------------
95      // NamingEnumeration Interface Methods 
96      // ------------------------------------------------------------------------
97  
98      /**
99       * @see javax.naming.NamingEnumeration#next()
100      */
101     public IndexEntry next() throws NamingException
102     {
103         returned.copy( prefetched );
104         prefetch();
105         return returned;
106     }
107 
108 
109     /**
110      * @see java.util.Enumeration#nextElement()
111      */
112     public IndexEntry nextElement()
113     {
114         try
115         {
116             return next();
117         }
118         catch ( NamingException ne )
119         {
120             throw new NoSuchElementException();
121         }
122     }
123 
124 
125     /**
126      * @see javax.naming.NamingEnumeration#hasMore()
127      */
128     public boolean hasMore()
129     {
130         return hasMore;
131     }
132 
133 
134     /**
135      * @see javax.naming.NamingEnumeration#hasMoreElements()
136      */
137     public boolean hasMoreElements()
138     {
139         return hasMore;
140     }
141 
142 
143     /**
144      * @see javax.naming.NamingEnumeration#close()
145      */
146     public void close() throws NamingException
147     {
148         hasMore = false;
149         underlying.close();
150     }
151 
152 
153     // ------------------------------------------------------------------------
154     // Private Methods 
155     // ------------------------------------------------------------------------
156 
157 
158     private void prefetch() throws NamingException
159     {
160         while ( underlying.hasMore() )
161         {
162             Tuple tuple = underlying.next();
163 
164             if ( swapKeyVal )
165             {
166                 throw new NotImplementedException();
167                 // tmp.setSwapped( tuple, null );
168             }
169             else
170             {
171                 tmp.setTuple( tuple, null );
172             }
173 
174             // If regex is null just transfer into prefetched from tmp record
175             // but if it is not then use it to match.  Successful match shorts
176             // while loop.
177             if ( null == re || re.matcher( ( String ) tmp.getValue() ).matches() )
178             {
179                 prefetched.copy( tmp );
180                 return;
181             }
182         }
183 
184         // If we got down here then cursor has been consumed without a match!
185         hasMore = false;
186     }
187 }