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    
021    package org.apache.directory.shared.ldap.subtree;
022    
023    
024    import java.io.StringReader;
025    import java.text.ParseException;
026    import java.util.Map;
027    
028    import org.apache.directory.shared.i18n.I18n;
029    
030    import antlr.RecognitionException;
031    import antlr.TokenStreamException;
032    
033    
034    /**
035     * A reusable wrapper around the antlr generated parser for an LDAP subtree
036     * specification as defined by <a href="http://www.faqs.org/rfcs/rfc3672.html">
037     * RFC 3672</a>. This class enables the reuse of the antlr parser/lexer pair
038     * without having to recreate the pair every time.
039     * 
040     * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
041     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
042     * @version $Rev: 437007 $
043     */
044    public class SubtreeSpecificationChecker
045    {
046        /** the antlr generated parser being wrapped */
047        private ReusableAntlrSubtreeSpecificationChecker parser;
048    
049        /** the antlr generated lexer being wrapped */
050        private ReusableAntlrSubtreeSpecificationCheckerLexer lexer;
051    
052    
053        /**
054         * Creates a subtree specification parser.
055         */
056        public SubtreeSpecificationChecker( Map oidsMap )
057        {
058            StringReader in = new StringReader( "" ); // place holder for the
059                                                        // first input
060            this.lexer = new ReusableAntlrSubtreeSpecificationCheckerLexer( in );
061            this.parser = new ReusableAntlrSubtreeSpecificationChecker( lexer );
062            this.parser.init(); // this method MUST be called while we cannot do
063                                // constructor overloading for antlr generated parser
064        }
065    
066    
067        /**
068         * Creates a normalizing subtree specification parser.
069         */
070        public SubtreeSpecificationChecker()
071        {
072            StringReader in = new StringReader( "" ); // place holder for the
073                                                      // first input
074            this.lexer = new ReusableAntlrSubtreeSpecificationCheckerLexer( in );
075            this.parser = new ReusableAntlrSubtreeSpecificationChecker( lexer );
076            this.parser.init(); // this method MUST be called while we cannot do
077                                // constructor overloading for antlr generated parser
078        }
079    
080    
081        /**
082         * Initializes the plumbing by creating a pipe and coupling the parser/lexer
083         * pair with it. param spec the specification to be parsed
084         */
085        private synchronized void reset( String spec )
086        {
087            StringReader in = new StringReader( spec + "end" ); // append end of
088                                                                // input token
089            this.lexer.prepareNextInput( in );
090            this.parser.resetState();
091        }
092    
093    
094        /**
095         * Parses a subtree specification without exhausting the parser.
096         * 
097         * @param spec
098         *            the specification to be parsed
099         * @throws ParseException
100         *             if there are any recognition errors (bad syntax)
101         */
102        public synchronized void parse( String spec ) throws ParseException
103        {
104            if ( spec == null || spec.trim().equals( "" ) )
105            {
106                return;
107            }
108    
109            reset( spec ); // reset and initialize the parser / lexer pair
110    
111            try
112            {
113                this.parser.wrapperEntryPoint();
114            }
115            catch ( TokenStreamException e )
116            {
117                String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
118                throw new ParseException( msg, 0 );
119            }
120            catch ( RecognitionException e )
121            {
122                String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
123                throw new ParseException( msg, e.getColumn() );
124            }
125            catch ( Exception e )
126            {
127                String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
128                throw new ParseException( msg, 0 );
129            }
130        }
131    
132    }