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