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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.aci;
22  
23  
24  import java.io.Reader;
25  
26  import antlr.CharBuffer;
27  import antlr.LexerSharedInputState;
28  
29  
30  /**
31   * A reusable lexer class extended from antlr generated lexer for an LDAP
32   * subtree specification as defined by <a
33   * href="http://www.faqs.org/rfcs/rfc3672.html"> RFC 3672</a>. This class
34   * enables the reuse of the antlr lexer without having to recreate the it every
35   * time as stated in <a
36   * href="http://www.antlr.org:8080/pipermail/antlr-interest/2003-April/003631.html">
37   * a Antlr Interest Group mail</a> .
38   * 
39   * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
40   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
41   */
42  class ReusableAntlrACIItemCheckerLexer extends AntlrACIItemCheckerLexer
43  {
44  
45      /** The saved case sensitive flag. */
46      private boolean savedCaseSensitive;
47  
48      /** The saved case sensitive literals flag. */
49      private boolean savedCaseSensitiveLiterals;
50  
51  
52      /**
53       * Creates a ReusableAntlrACIItemCheckerLexer instance.
54       * 
55       * @param in
56       *            the input to the lexer
57       */
58      public ReusableAntlrACIItemCheckerLexer( Reader in )
59      {
60          super( in );
61          savedCaseSensitive = getCaseSensitive();
62          savedCaseSensitiveLiterals = getCaseSensitiveLiterals();
63      }
64  
65  
66      /**
67       * Resets the state of an antlr lexer and initializes it with new input.
68       * 
69       * @param in
70       *            the input to the lexer
71       */
72      public void prepareNextInput( Reader in )
73      {
74          CharBuffer buf = new CharBuffer( in );
75          LexerSharedInputState state = new LexerSharedInputState( buf );
76          this.setInputState( state );
77  
78          this.setCaseSensitive( savedCaseSensitive );
79  
80          // no set method for this protected field.
81          this.caseSensitiveLiterals = savedCaseSensitiveLiterals;
82      }
83  }