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.model.subtree;
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.NormalizerMappingResolver;
029import org.apache.directory.api.ldap.model.schema.SchemaManager;
030
031import antlr.RecognitionException;
032import antlr.TokenStreamException;
033
034
035/**
036 * A reusable wrapper around the antlr generated parser for an LDAP subtree
037 * specification as defined by <a href="http://www.faqs.org/rfcs/rfc3672.html">
038 * RFC 3672</a>. This class enables the reuse of the antlr parser/lexer pair
039 * without having to recreate the pair every time.
040 * 
041 * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
042 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
043 */
044public class SubtreeSpecificationParser
045{
046    /** the antlr generated parser being wrapped */
047    private ReusableAntlrSubtreeSpecificationParser parser;
048
049    /** the antlr generated lexer being wrapped */
050    private ReusableAntlrSubtreeSpecificationLexer lexer;
051
052    private final boolean isNormalizing;
053
054
055    /**
056     * Creates a subtree specification parser.
057     */
058    public SubtreeSpecificationParser( SchemaManager schemaManager )
059    {
060        StringReader in = new StringReader( "" ); // place holder for the
061                                                  // first input
062        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
063        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
064        this.parser.init( schemaManager ); // this method MUST be called while we cannot do
065        // constructor overloading for antlr generated parser
066        this.isNormalizing = false;
067    }
068
069
070    /**
071     * Creates a normalizing subtree specification parser.
072     */
073    public SubtreeSpecificationParser( @SuppressWarnings("rawtypes") NormalizerMappingResolver resolver,
074        SchemaManager schemaManager )
075    {
076        StringReader in = new StringReader( "" ); // place holder for the
077                                                  // first input
078        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
079        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
080        this.parser.setNormalizerMappingResolver( resolver );
081        this.parser.init( schemaManager ); // this method MUST be called while we cannot do
082        // constructor overloading for antlr generated parser
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. param spec the specification to be parsed
090     */
091    private synchronized void reset( String spec )
092    {
093        StringReader in = new StringReader( spec + "end" ); // append end of
094                                                            // input token
095        this.lexer.prepareNextInput( in );
096        this.parser.resetState();
097    }
098
099
100    /**
101     * Parses a subtree specification without exhausting the parser.
102     * 
103     * @param spec
104     *            the specification to be parsed
105     * @return the specification bean
106     * @throws ParseException
107     *             if there are any recognition errors (bad syntax)
108     */
109    public synchronized SubtreeSpecification parse( String spec ) throws ParseException
110    {
111        SubtreeSpecification ss = null;
112
113        if ( spec == null || spec.trim().equals( "" ) )
114        {
115            return null;
116        }
117
118        reset( spec ); // reset and initialize the parser / lexer pair
119
120        try
121        {
122            ss = this.parser.wrapperEntryPoint();
123        }
124        catch ( TokenStreamException e )
125        {
126            String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
127            throw new ParseException( msg, 0 );
128        }
129        catch ( RecognitionException e )
130        {
131            String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
132            throw new ParseException( msg, e.getColumn() );
133        }
134        catch ( Exception e )
135        {
136            String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
137            throw new ParseException( msg, 0 );
138        }
139
140        return ss;
141    }
142
143
144    /**
145     * Tests to see if this parser is normalizing.
146     * 
147     * @return true if it normalizes false otherwise
148     */
149    public boolean isNormizing()
150    {
151        return this.isNormalizing;
152    }
153}