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 */
020package org.apache.directory.api.ldap.model.schema.parsers;
021
022
023import java.io.Reader;
024
025import org.apache.directory.api.ldap.model.schema.syntaxes.AntlrSchemaLexer;
026
027import antlr.CharBuffer;
028import antlr.LexerSharedInputState;
029
030
031/**
032 * A reusable lexer class extended from antlr generated lexer for an LDAP
033 * schema as defined in RFC 4512. This class
034 * enables the reuse of the antlr lexer without having to recreate the it every
035 * time as stated in <a
036 * href="http://www.antlr.org:8080/pipermail/antlr-interest/2003-April/003631.html">
037 * a Antlr Interest Group mail</a> .
038 * 
039 * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
040 */
041public class ReusableAntlrSchemaLexer extends AntlrSchemaLexer
042{
043    private boolean savedCaseSensitive;
044
045    private boolean savedCaseSensitiveLiterals;
046
047
048    /**
049     * Creates a ReusableAntlrSchemaLexer instance.
050     * 
051     * @param in
052     *            the input to the lexer
053     */
054    public ReusableAntlrSchemaLexer( Reader in )
055    {
056        super( in );
057        savedCaseSensitive = getCaseSensitive();
058        savedCaseSensitiveLiterals = getCaseSensitiveLiterals();
059    }
060
061
062    /**
063     * Resets the state of an antlr lexer and initializes it with new input.
064     * 
065     * @param in
066     *            the input to the lexer
067     */
068    public void prepareNextInput( Reader in )
069    {
070        CharBuffer buf = new CharBuffer( in );
071        LexerSharedInputState state = new LexerSharedInputState( buf );
072        this.setInputState( state );
073
074        this.setCaseSensitive( savedCaseSensitive );
075
076        // no set method for this protected field.
077        this.caseSensitiveLiterals = savedCaseSensitiveLiterals;
078    }
079}