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 */
020
021package org.apache.directory.api.ldap.model.subtree;
022
023
024import java.io.Reader;
025
026import org.apache.directory.api.ldap.model.subtree.AntlrSubtreeSpecificationCheckerLexer;
027
028import antlr.CharBuffer;
029import antlr.LexerSharedInputState;
030
031
032/**
033 * A reusable lexer class extended from antlr generated lexer for an LDAP
034 * subtree specification as defined by <a
035 * href="http://www.faqs.org/rfcs/rfc3672.html"> RFC 3672</a>. This class
036 * enables the reuse of the antlr lexer without having to recreate the it every
037 * time as stated in <a
038 * href="http://www.antlr.org:8080/pipermail/antlr-interest/2003-April/003631.html">
039 * a Antlr Interest Group mail</a> .
040 * 
041 * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
042 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
043 */
044public class ReusableAntlrSubtreeSpecificationCheckerLexer extends AntlrSubtreeSpecificationCheckerLexer
045{
046    private boolean savedCaseSensitive;
047
048    private boolean savedCaseSensitiveLiterals;
049
050
051    /**
052     * Creates a ReusableAntlrSubtreeSpecificationLexer instance.
053     * 
054     * @param in
055     *            the input to the lexer
056     */
057    public ReusableAntlrSubtreeSpecificationCheckerLexer( Reader in )
058    {
059        super( in );
060        savedCaseSensitive = getCaseSensitive();
061        savedCaseSensitiveLiterals = getCaseSensitiveLiterals();
062    }
063
064
065    /**
066     * Resets the state of an antlr lexer and initializes it with new input.
067     * 
068     * @param in
069     *            the input to the lexer
070     */
071    public void prepareNextInput( Reader in )
072    {
073        CharBuffer buf = new CharBuffer( in );
074        LexerSharedInputState state = new LexerSharedInputState( buf );
075        this.setInputState( state );
076
077        this.setCaseSensitive( savedCaseSensitive );
078
079        // no set method for this protected field.
080        this.caseSensitiveLiterals = savedCaseSensitiveLiterals;
081    }
082}