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.aci;
022
023
024import java.io.StringReader;
025import java.text.ParseException;
026
027import org.apache.directory.api.i18n.I18n;
028import org.apache.directory.api.ldap.model.schema.SchemaManager;
029import org.apache.directory.api.util.StringConstants;
030
031import antlr.RecognitionException;
032import antlr.TokenStreamException;
033
034
035/**
036 * A reusable wrapper around the antlr generated parser for an ACIItem as
037 * defined by X.501. This class enables the reuse of the antlr parser/lexer pair
038 * without having to recreate them every time.
039 * 
040 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
041 */
042public class ACIItemChecker
043{
044    /** the antlr generated parser being wrapped */
045    private ReusableAntlrACIItemParser checker;
046
047    /** the antlr generated lexer being wrapped */
048    private ReusableAntlrACIItemLexer lexer;
049
050
051    /**
052     * Creates a ACIItem parser.
053     *
054     * @param schemaManager the schema manager
055     */
056    public ACIItemChecker( SchemaManager schemaManager )
057    {
058        this.lexer = new ReusableAntlrACIItemLexer( new StringReader( "" ) );
059        this.checker = new ReusableAntlrACIItemParser( lexer );
060        this.checker.init( schemaManager );
061    }
062
063
064    /**
065     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
066     * pair with it. param spec the specification to be parsed
067     */
068    private synchronized void reset( String spec )
069    {
070        StringReader in = new StringReader( spec );
071        this.lexer.prepareNextInput( in );
072        this.checker.resetState();
073    }
074
075
076    /**
077     * Parses an ACIItem without exhausting the parser.
078     * 
079     * @param spec
080     *            the specification to be parsed
081     * @throws ParseException
082     *             if there are any recognition errors (bad syntax)
083     */
084    public synchronized void parse( String spec ) throws ParseException
085    {
086        if ( spec == null || StringConstants.EMPTY .equals( spec.trim() ) )
087        {
088            return;
089        }
090
091        // reset and initialize the parser / lexer pair
092        reset( spec );
093
094        try
095        {
096            this.checker.wrapperEntryPoint();
097        }
098        catch ( TokenStreamException e )
099        {
100            throw new ParseException( I18n
101                .err( I18n.ERR_04004_PARSER_FAILURE_ACI_ITEM, spec, e.getLocalizedMessage() ), 0 );
102        }
103        catch ( RecognitionException e )
104        {
105            throw new ParseException( I18n
106                .err( I18n.ERR_04004_PARSER_FAILURE_ACI_ITEM, spec, e.getLocalizedMessage() ), e.getColumn() );
107        }
108    }
109
110}