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.shared.ldap.trigger;
022
023
024import java.io.StringReader;
025import java.text.ParseException;
026
027import org.apache.directory.shared.i18n.I18n;
028import org.apache.directory.shared.ldap.model.schema.NormalizerMappingResolver;
029
030import antlr.RecognitionException;
031import antlr.TokenStreamException;
032
033
034/**
035 * A reusable wrapper around the ANTLR generated parser for a
036 * TriggerSpecification. This class enables the reuse of the antlr parser/lexer
037 * pair without having to recreate them every time.
038 * 
039 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
040 */
041public class TriggerSpecificationParser
042{
043    /** the antlr generated parser being wrapped */
044    private ReusableAntlrTriggerSpecificationParser parser;
045
046    /** the antlr generated lexer being wrapped */
047    private ReusableAntlrTriggerSpecificationLexer lexer;
048
049    private final boolean isNormalizing;
050
051
052    /**
053     * Creates a TriggerSpecification parser.
054     */
055    public TriggerSpecificationParser()
056    {
057        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
058        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
059
060        this.parser.init(); // this method MUST be called while we cannot do
061        // constructor overloading for antlr generated parser
062        this.isNormalizing = false;
063    }
064
065
066    /**
067     * Creates a normalizing TriggerSpecification parser.
068     *
069     * @param resolver the resolver
070     */
071    public TriggerSpecificationParser( NormalizerMappingResolver resolver )
072    {
073        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
074        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
075
076        this.parser.setNormalizerMappingResolver( resolver );
077        this.parser.init(); // this method MUST be called while we cannot do
078        // constructor overloading for ANTLR generated parser
079        this.isNormalizing = true;
080    }
081
082
083    /**
084     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
085     * pair with it.
086     * 
087     * @param
088     *          spec the specification to be parsed
089     */
090    private synchronized void reset( String spec )
091    {
092        StringReader in = new StringReader( spec );
093        this.lexer.prepareNextInput( in );
094        this.parser.resetState();
095    }
096
097
098    /**
099     * Parses an TriggerSpecification without exhausting the parser.
100     * 
101     * @param spec
102     *          the specification to be parsed
103     * @return the specification bean
104     * @throws ParseException
105     *          if there are any recognition errors (bad syntax)
106     */
107    public synchronized TriggerSpecification parse( String spec ) throws ParseException
108    {
109        TriggerSpecification triggerSpecification = null;
110
111        if ( spec == null || spec.trim().equals( "" ) )
112        {
113            return null;
114        }
115
116        reset( spec ); // reset and initialize the parser / lexer pair
117
118        try
119        {
120            triggerSpecification = this.parser.wrapperEntryPoint();
121        }
122        catch ( TokenStreamException e )
123        {
124            String msg = I18n.err( I18n.ERR_04333, spec, e.getLocalizedMessage() );
125            throw new ParseException( msg, 0 );
126        }
127        catch ( RecognitionException e )
128        {
129            String msg = I18n.err( I18n.ERR_04333, spec, e.getLocalizedMessage() );
130            throw new ParseException( msg, e.getColumn() );
131        }
132        
133        return triggerSpecification;
134
135    }
136
137
138    /**
139     * Tests to see if this parser is normalizing.
140     * 
141     * @return true if it normalizes false otherwise
142     */
143    public boolean isNormizing()
144    {
145        return this.isNormalizing;
146    }
147}