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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  
21  package org.apache.directory.api.ldap.model.subtree;
22  
23  
24  import java.io.Reader;
25  
26  import org.apache.directory.api.ldap.model.subtree.AntlrSubtreeSpecificationLexer;
27  
28  import antlr.CharBuffer;
29  import antlr.LexerSharedInputState;
30  
31  
32  /**
33   * A reusable lexer class extended from antlr generated lexer for an LDAP
34   * subtree specification as defined by <a
35   * href="http://www.faqs.org/rfcs/rfc3672.html"> RFC 3672</a>. This class
36   * enables the reuse of the antlr lexer without having to recreate the it every
37   * time as stated in <a
38   * href="http://www.antlr.org:8080/pipermail/antlr-interest/2003-April/003631.html">
39   * a Antlr Interest Group mail</a> .
40   * 
41   * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
42   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
43   */
44  public class ReusableAntlrSubtreeSpecificationLexer extends AntlrSubtreeSpecificationLexer
45  {
46      private boolean savedCaseSensitive;
47  
48      private boolean savedCaseSensitiveLiterals;
49  
50  
51      /**
52       * Creates a ReusableAntlrSubtreeSpecificationLexer instance.
53       * 
54       * @param in
55       *            the input to the lexer
56       */
57      public ReusableAntlrSubtreeSpecificationLexer( Reader in )
58      {
59          super( in );
60          savedCaseSensitive = getCaseSensitive();
61          savedCaseSensitiveLiterals = getCaseSensitiveLiterals();
62      }
63  
64  
65      /**
66       * Resets the state of an antlr lexer and initializes it with new input.
67       * 
68       * @param in
69       *            the input to the lexer
70       */
71      public void prepareNextInput( Reader in )
72      {
73          CharBuffer buf = new CharBuffer( in );
74          LexerSharedInputState state = new LexerSharedInputState( buf );
75          this.setInputState( state );
76  
77          this.setCaseSensitive( savedCaseSensitive );
78  
79          // no set method for this protected field.
80          this.caseSensitiveLiterals = savedCaseSensitiveLiterals;
81      }
82  }