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.trigger;
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.Normalizer;
029import org.apache.directory.api.ldap.model.schema.NormalizerMappingResolver;
030import org.apache.directory.api.util.Strings;
031
032import antlr.RecognitionException;
033import antlr.TokenStreamException;
034
035
036/**
037 * A reusable wrapper around the ANTLR generated parser for a
038 * TriggerSpecification. This class enables the reuse of the antlr parser/lexer
039 * pair without having to recreate them every time.
040 * 
041 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
042 */
043public class TriggerSpecificationParser
044{
045    /** the antlr generated parser being wrapped */
046    private ReusableAntlrTriggerSpecificationParser parser;
047
048    /** the antlr generated lexer being wrapped */
049    private ReusableAntlrTriggerSpecificationLexer lexer;
050
051    private final boolean isNormalizing;
052
053
054    /**
055     * Creates a TriggerSpecification parser.
056     */
057    public TriggerSpecificationParser()
058    {
059        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
060        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
061
062        // this method MUST be called while we cannot do
063        // constructor overloading for antlr generated parser
064        this.parser.init();
065        this.isNormalizing = false;
066    }
067
068
069    /**
070     * Creates a normalizing TriggerSpecification parser.
071     *
072     * @param resolver the resolver
073     */
074    public TriggerSpecificationParser( NormalizerMappingResolver<Normalizer> resolver )
075    {
076        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
077        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
078
079        this.parser.setNormalizerMappingResolver( resolver );
080        // this method MUST be called while we cannot do
081        // constructor overloading for ANTLR generated parser
082        this.parser.init();
083        this.isNormalizing = true;
084    }
085
086
087    /**
088     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
089     * pair with it.
090     * 
091     * @param
092     *          spec the specification to be parsed
093     */
094    private synchronized void reset( String spec )
095    {
096        StringReader in = new StringReader( spec );
097        this.lexer.prepareNextInput( in );
098        this.parser.resetState();
099    }
100
101
102    /**
103     * Parses an TriggerSpecification without exhausting the parser.
104     * 
105     * @param spec
106     *          the specification to be parsed
107     * @return the specification bean
108     * @throws ParseException
109     *          if there are any recognition errors (bad syntax)
110     */
111    public synchronized TriggerSpecification parse( String spec ) throws ParseException
112    {
113        TriggerSpecification triggerSpecification;
114
115        if ( Strings.isEmpty( spec ) )
116        {
117            return null;
118        }
119
120        // reset and initialize the parser / lexer pair
121        reset( spec );
122
123        try
124        {
125            triggerSpecification = this.parser.wrapperEntryPoint();
126        }
127        catch ( TokenStreamException e )
128        {
129            String msg = I18n.err( I18n.ERR_11002_TRIGGER_SPECIFICATION_PARSER_FAILURE, spec, e.getLocalizedMessage() );
130            
131            throw new ParseException( msg, 0 );
132        }
133        catch ( RecognitionException e )
134        {
135            String msg = I18n.err( I18n.ERR_11002_TRIGGER_SPECIFICATION_PARSER_FAILURE, spec, e.getLocalizedMessage() );
136            
137            throw new ParseException( msg, e.getColumn() );
138        }
139
140        return triggerSpecification;
141
142    }
143
144
145    /**
146     * Tests to see if this parser is normalizing.
147     * 
148     * @return true if it normalizes false otherwise
149     */
150    public boolean isNormizing()
151    {
152        return this.isNormalizing;
153    }
154}