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
021 package org.apache.directory.shared.ldap.trigger;
022
023
024 import java.io.StringReader;
025 import java.text.ParseException;
026
027 import org.apache.directory.shared.ldap.schema.NormalizerMappingResolver;
028
029 import antlr.RecognitionException;
030 import antlr.TokenStreamException;
031
032
033 /**
034 * A reusable wrapper around the ANTLR generated parser for a
035 * TriggerSpecification. This class enables the reuse of the antlr parser/lexer
036 * pair without having to recreate them every time.
037 *
038 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
039 * @version $Rev:$, $Date:$
040 */
041 public class TriggerSpecificationParser
042 {
043 /** the antlr generated parser being wrapped */
044 private ReusableAntlrTriggerSpecificationParser parser;
045
046 /** the antlr generated lexer being wrapped */
047 private ReusableAntlrTriggerSpecificationLexer lexer;
048
049 private final boolean isNormalizing;
050
051
052 /**
053 * Creates a TriggerSpecification parser.
054 */
055 public TriggerSpecificationParser()
056 {
057 this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
058 this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
059
060 this.parser.init(); // this method MUST be called while we cannot do
061 // constructor overloading for antlr generated parser
062 this.isNormalizing = false;
063 }
064
065
066 /**
067 * Creates a normalizing TriggerSpecification parser.
068 */
069 public TriggerSpecificationParser( NormalizerMappingResolver resolver )
070 {
071 this.lexer = new ReusableAntlrTriggerSpecificationLexer( new StringReader( "" ) );
072 this.parser = new ReusableAntlrTriggerSpecificationParser( lexer );
073
074 this.parser.setNormalizerMappingResolver( resolver );
075 this.parser.init(); // this method MUST be called while we cannot do
076 // constructor overloading for ANTLR generated parser
077 this.isNormalizing = true;
078 }
079
080
081 /**
082 * Initializes the plumbing by creating a pipe and coupling the parser/lexer
083 * pair with it.
084 *
085 * @param
086 * spec the specification to be parsed
087 */
088 private synchronized void reset( String spec )
089 {
090 StringReader in = new StringReader( spec );
091 this.lexer.prepareNextInput( in );
092 this.parser.resetState();
093 }
094
095
096 /**
097 * Parses an TriggerSpecification without exhausting the parser.
098 *
099 * @param spec
100 * the specification to be parsed
101 * @return the specification bean
102 * @throws ParseException
103 * if there are any recognition errors (bad syntax)
104 */
105 public synchronized TriggerSpecification parse( String spec ) throws ParseException
106 {
107 TriggerSpecification triggerSpecification = null;
108
109 if ( spec == null || spec.trim().equals( "" ) )
110 {
111 return null;
112 }
113
114 reset( spec ); // reset and initialize the parser / lexer pair
115
116 try
117 {
118 triggerSpecification = this.parser.wrapperEntryPoint();
119 }
120 catch ( TokenStreamException e )
121 {
122 String msg = "Parser failure on Trigger Specification:\n\t" + spec;
123 msg += "\nAntlr exception trace:\n" + e.getMessage();
124 throw new ParseException( msg, 0 );
125 }
126 catch ( RecognitionException e )
127 {
128 String msg = "Parser failure on Trigger Specification:\n\t" + spec;
129 msg += "\nAntlr exception trace:\n" + e.getMessage();
130 throw new ParseException( msg, e.getColumn() );
131 }
132
133 return triggerSpecification;
134
135 }
136
137
138 /**
139 * Tests to see if this parser is normalizing.
140 *
141 * @return true if it normalizes false otherwise
142 */
143 public boolean isNormizing()
144 {
145 return this.isNormalizing;
146 }
147 }