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     * @param schemaManager The SchemaManager
059     */
060    public SubtreeSpecificationParser( SchemaManager schemaManager )
061    {
062        // place holder for the first input
063        StringReader in = new StringReader( "" );
064        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
065        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
066        // this method MUST be called while we cannot do
067        // constructor overloading for antlr generated parser
068        this.parser.init( schemaManager );
069        this.isNormalizing = false;
070    }
071
072
073    /**
074     * Creates a normalizing subtree specification parser.
075     * 
076     * @param resolver The resolver to use
077     * @param schemaManager The SchemaManager
078     */
079    public SubtreeSpecificationParser( @SuppressWarnings("rawtypes") NormalizerMappingResolver resolver,
080        SchemaManager schemaManager )
081    {
082        // place holder for the first input
083        StringReader in = new StringReader( "" );
084        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
085        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
086        this.parser.setNormalizerMappingResolver( resolver );
087        // this method MUST be called while we cannot do
088        // constructor overloading for antlr generated parser
089        this.parser.init( schemaManager );
090        this.isNormalizing = true;
091    }
092
093
094    /**
095     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
096     * pair with it. param spec the specification to be parsed
097     */
098    private synchronized void reset( String spec )
099    {
100        // append end of input token
101        StringReader in = new StringReader( spec + "end" );
102        this.lexer.prepareNextInput( in );
103        this.parser.resetState();
104    }
105
106
107    /**
108     * Parses a subtree specification without exhausting the parser.
109     * 
110     * @param spec
111     *            the specification to be parsed
112     * @return the specification bean
113     * @throws ParseException
114     *             if there are any recognition errors (bad syntax)
115     */
116    public synchronized SubtreeSpecification parse( String spec ) throws ParseException
117    {
118        SubtreeSpecification ss;
119
120        if ( ( spec == null ) || ( spec.trim().length() == 0 ) )
121        {
122            return null;
123        }
124
125        // reset and initialize the parser / lexer pair
126        reset( spec );
127
128        try
129        {
130            ss = this.parser.wrapperEntryPoint();
131        }
132        catch ( TokenStreamException | RecognitionException e )
133        {
134            String msg = I18n.err( I18n.ERR_04329, spec, e.getLocalizedMessage() );
135            throw new ParseException( msg, 0 );
136        }
137
138        return ss;
139    }
140
141
142    /**
143     * Tests to see if this parser is normalizing.
144     * 
145     * @return true if it normalizes false otherwise
146     */
147    public boolean isNormizing()
148    {
149        return this.isNormalizing;
150    }
151}