001/*
002
003
004 *  Licensed to the Apache Software Foundation (ASF) under one
005 *  or more contributor license agreements.  See the NOTICE file
006 *  distributed with this work for additional information
007 *  regarding copyright ownership.  The ASF licenses this file
008 *  to you under the Apache License, Version 2.0 (the
009 *  "License"); you may not use this file except in compliance
010 *  with the License.  You may obtain a copy of the License at
011 *  
012 *    http://www.apache.org/licenses/LICENSE-2.0
013 *  
014 *  Unless required by applicable law or agreed to in writing,
015 *  software distributed under the License is distributed on an
016 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 *  KIND, either express or implied.  See the License for the
018 *  specific language governing permissions and limitations
019 *  under the License. 
020 *  
021 */
022
023package org.apache.directory.api.ldap.model.subtree;
024
025
026import java.io.StringReader;
027import java.text.ParseException;
028
029import org.apache.directory.api.i18n.I18n;
030import org.apache.directory.api.ldap.model.schema.NormalizerMappingResolver;
031import org.apache.directory.api.ldap.model.schema.SchemaManager;
032import org.apache.directory.api.util.Strings;
033
034import antlr.RecognitionException;
035import antlr.TokenStreamException;
036
037
038/**
039 * A reusable wrapper around the antlr generated parser for an LDAP subtree
040 * specification as defined by <a href="http://www.faqs.org/rfcs/rfc3672.html">
041 * RFC 3672</a>. This class enables the reuse of the antlr parser/lexer pair
042 * without having to recreate the pair every time.
043 * 
044 * @see <a href="http://www.faqs.org/rfcs/rfc3672.html">RFC 3672</a>
045 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
046 */
047public class SubtreeSpecificationParser
048{
049    /** the antlr generated parser being wrapped */
050    private ReusableAntlrSubtreeSpecificationParser parser;
051
052    /** the antlr generated lexer being wrapped */
053    private ReusableAntlrSubtreeSpecificationLexer lexer;
054
055    private final boolean isNormalizing;
056
057
058    /**
059     * Creates a subtree specification parser.
060     * 
061     * @param schemaManager The SchemaManager
062     */
063    public SubtreeSpecificationParser( SchemaManager schemaManager )
064    {
065        // place holder for the first input
066        StringReader in = new StringReader( "" );
067        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
068        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
069        // this method MUST be called while we cannot do
070        // constructor overloading for antlr generated parser
071        this.parser.init( schemaManager );
072        this.isNormalizing = false;
073    }
074
075
076    /**
077     * Creates a normalizing subtree specification parser.
078     * 
079     * @param resolver The resolver to use
080     * @param schemaManager The SchemaManager
081     */
082    public SubtreeSpecificationParser( @SuppressWarnings("rawtypes") NormalizerMappingResolver resolver,
083        SchemaManager schemaManager )
084    {
085        // place holder for the first input
086        StringReader in = new StringReader( "" );
087        this.lexer = new ReusableAntlrSubtreeSpecificationLexer( in );
088        this.parser = new ReusableAntlrSubtreeSpecificationParser( lexer );
089        this.parser.setNormalizerMappingResolver( resolver );
090        // this method MUST be called while we cannot do
091        // constructor overloading for antlr generated parser
092        this.parser.init( schemaManager );
093        this.isNormalizing = true;
094    }
095
096
097    /**
098     * Initializes the plumbing by creating a pipe and coupling the parser/lexer
099     * pair with it.
100     * 
101     * @param spec The specification to parse
102     */
103    private synchronized void reset( String spec )
104    {
105        // append end of input token
106        StringReader in = new StringReader( spec + "end" );
107        this.lexer.prepareNextInput( in );
108        this.parser.resetState();
109    }
110
111
112    /**
113     * Parses a subtree specification without exhausting the parser.
114     * 
115     * @param spec
116     *            the specification to be parsed
117     * @return the specification bean
118     * @throws ParseException
119     *             if there are any recognition errors (bad syntax)
120     */
121    public synchronized SubtreeSpecification parse( String spec ) throws ParseException
122    {
123        SubtreeSpecification ss;
124
125        if ( ( spec == null ) || Strings.isEmpty( spec.trim() ) )
126        {
127            return null;
128        }
129
130        // reset and initialize the parser / lexer pair
131        reset( spec );
132
133        try
134        {
135            ss = this.parser.wrapperEntryPoint();
136        }
137        catch ( TokenStreamException | RecognitionException e )
138        {
139            String msg = I18n.err( I18n.ERR_13028_SUBTREE_SPEC_PARSER_FAILURE, spec, e.getLocalizedMessage() );
140            throw new ParseException( msg, 0 );
141        }
142
143        return ss;
144    }
145
146
147    /**
148     * Tests to see if this parser is normalizing.
149     * 
150     * @return true if it normalizes false otherwise
151     */
152    public boolean isNormizing()
153    {
154        return this.isNormalizing;
155    }
156}