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;
030
031import antlr.RecognitionException;
032import antlr.TokenStreamException;
033
034
035/**
036 * A reusable wrapper around the ANTLR generated parser for a
037 * TriggerSpecification. This class enables the reuse of the antlr parser/lexer
038 * pair without having to recreate them every time.
039 * 
040 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
041 */
042public class TriggerSpecificationParser
043{
044    /** the antlr generated parser being wrapped */
045    private ReusableAntlrTriggerSpecificationParser parser;
046
047    /** the antlr generated lexer being wrapped */
048    private ReusableAntlrTriggerSpecificationLexer lexer;
049
050    private final boolean isNormalizing;
051
052
053    /**
054     * Creates a TriggerSpecification parser.
055     */
056    public TriggerSpecificationParser()
057    {
058        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
059        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
060
061        this.parser.init(); // this method MUST be called while we cannot do
062        // constructor overloading for antlr generated parser
063        this.isNormalizing = false;
064    }
065
066
067    /**
068     * Creates a normalizing TriggerSpecification parser.
069     *
070     * @param resolver the resolver
071     */
072    public TriggerSpecificationParser( NormalizerMappingResolver<Normalizer> resolver )
073    {
074        this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
075        this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
076
077        this.parser.setNormalizerMappingResolver( resolver );
078        this.parser.init(); // this method MUST be called while we cannot do
079        // constructor overloading for ANTLR generated parser
080        this.isNormalizing = true;
081    }
082
083
084    /**
085     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
086     * pair with it.
087     * 
088     * @param
089     *          spec the specification to be parsed
090     */
091    private synchronized void reset( String spec )
092    {
093        StringReader in = new StringReader( spec );
094        this.lexer.prepareNextInput( in );
095        this.parser.resetState();
096    }
097
098
099    /**
100     * Parses an TriggerSpecification without exhausting the parser.
101     * 
102     * @param spec
103     *          the specification to be parsed
104     * @return the specification bean
105     * @throws ParseException
106     *          if there are any recognition errors (bad syntax)
107     */
108    public synchronized TriggerSpecification parse( String spec ) throws ParseException
109    {
110        TriggerSpecification triggerSpecification = null;
111
112        if ( spec == null || spec.trim().equals( "" ) )
113        {
114            return null;
115        }
116
117        reset( spec ); // reset and initialize the parser / lexer pair
118
119        try
120        {
121            triggerSpecification = this.parser.wrapperEntryPoint();
122        }
123        catch ( TokenStreamException e )
124        {
125            String msg = I18n.err( I18n.ERR_04333, spec, e.getLocalizedMessage() );
126            throw new ParseException( msg, 0 );
127        }
128        catch ( RecognitionException e )
129        {
130            String msg = I18n.err( I18n.ERR_04333, spec, e.getLocalizedMessage() );
131            throw new ParseException( msg, e.getColumn() );
132        }
133
134        return triggerSpecification;
135
136    }
137
138
139    /**
140     * Tests to see if this parser is normalizing.
141     * 
142     * @return true if it normalizes false otherwise
143     */
144    public boolean isNormizing()
145    {
146        return this.isNormalizing;
147    }
148}