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Java > Open Source Codes > org > apache > ldap > server > db > IndexEnumeration


1 /*
2  * Copyright 2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17 package org.apache.ldap.server.db;
18
19
20 import org.apache.regexp.RE;
21
22 import javax.naming.NamingEnumeration JavaDoc;
23 import javax.naming.NamingException JavaDoc;
24 import java.util.NoSuchElementException JavaDoc;
25
26
27 /**
28  * A NamingEnumeration over an Index which returns IndexRecords.
29  *
30  * @author <a HREF="mailto:dev@directory.apache.org">Apache Directory Project</a>
31  * @version $Rev: 169198 $
32  */
33 public class IndexEnumeration
34     implements NamingEnumeration JavaDoc
35 {
36     /** */
37     private final RE re;
38     /** */
39     private final IndexRecord tmp = new IndexRecord();
40     /** */
41     private final IndexRecord returned = new IndexRecord();
42     /** */
43     private final IndexRecord prefetched = new IndexRecord();
44     /** */
45     private final boolean swapKeyVal;
46     /** */
47     private final NamingEnumeration JavaDoc underlying;
48
49     /** */
50     private boolean hasMore = true;
51
52
53     // ------------------------------------------------------------------------
54 // C O N S T R U C T O R S
55 // ------------------------------------------------------------------------
56
57
58     /**
59      * TODO Domument me!
60      *
61      * @param list TODO
62      * @throws NamingException TODO
63      */
64     public IndexEnumeration( NamingEnumeration JavaDoc list ) throws NamingException JavaDoc
65     {
66         this( list, false, null );
67     }
68
69
70     /**
71      * TODO Domument me!
72      *
73      * @param list TODO
74      * @param swapKeyVal TODO
75      * @throws NamingException TODO
76      */
77     public IndexEnumeration( NamingEnumeration JavaDoc list, boolean swapKeyVal )
78         throws NamingException JavaDoc
79     {
80         this( list, swapKeyVal, null );
81     }
82
83
84     /**
85      * TODO Domument me!
86      *
87      * @param list TODO
88      * @param swapKeyVal TODO
89      * @param regex TODO
90      * @throws NamingException TODO
91      */
92     public IndexEnumeration( NamingEnumeration JavaDoc list, boolean swapKeyVal,
93                              RE regex )
94         throws NamingException JavaDoc
95     {
96         re = regex;
97         underlying = list;
98         this.swapKeyVal = swapKeyVal;
99
100         if ( ! underlying.hasMore() )
101         {
102             hasMore = false;
103             return;
104         }
105
106         prefetch();
107     }
108
109
110     // ------------------------------------------------------------------------
111 // NamingEnumeration Interface Methods
112 // ------------------------------------------------------------------------
113
114
115     /**
116      * @see javax.naming.NamingEnumeration#next()
117      */
118     public Object JavaDoc next()
119         throws NamingException JavaDoc
120     {
121         returned.copy( prefetched );
122         prefetch();
123         return returned;
124     }
125     
126     
127     /**
128      * @see java.util.Enumeration#nextElement()
129      */
130     public Object JavaDoc nextElement()
131     {
132         try
133         {
134             return next();
135         }
136         catch ( NamingException JavaDoc ne )
137         {
138             throw new NoSuchElementException JavaDoc();
139         }
140     }
141
142
143     /**
144      * @see javax.naming.NamingEnumeration#hasMore()
145      */
146     public boolean hasMore()
147     {
148         return hasMore;
149     }
150
151
152     /**
153      * @see javax.naming.NamingEnumeration#hasMoreElements()
154      */
155     public boolean hasMoreElements()
156     {
157         return hasMore;
158     }
159
160
161     /**
162      * @see javax.naming.NamingEnumeration#close()
163      */
164     public void close() throws NamingException JavaDoc
165     {
166         hasMore = false;
167         underlying.close();
168     }
169
170
171     // ------------------------------------------------------------------------
172 // Private Methods
173 // ------------------------------------------------------------------------
174
175
176     /**
177      * TODO Document me!
178      *
179      * @throws NamingException TODO
180      */
181     private void prefetch() throws NamingException JavaDoc
182     {
183         while ( underlying.hasMore() )
184         {
185             Tuple tuple = ( Tuple ) underlying.next();
186
187             if ( swapKeyVal )
188             {
189                 tmp.setSwapped( tuple, null );
190             }
191             else
192             {
193                 tmp.setTuple( tuple, null );
194             }
195
196             // If regex is null just transfer into prefetched from tmp record
197 // but if it is not then use it to match. Successful match shorts
198 // while loop.
199 if ( null == re || re.match( ( String JavaDoc ) tmp.getIndexKey() ) )
200             {
201                 prefetched.copy( tmp );
202                 return;
203             }
204         }
205
206         // If we got down here then cursor has been consumed without a match!
207 hasMore = false;
208     }
209 }
210
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