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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  
21  package org.apache.directory.api.ldap.aci;
22  
23  
24  import java.io.StringReader;
25  import java.text.ParseException;
26  
27  import org.apache.directory.api.i18n.I18n;
28  import org.apache.directory.api.ldap.model.schema.SchemaManager;
29  import org.apache.directory.api.util.StringConstants;
30  
31  import antlr.RecognitionException;
32  import antlr.TokenStreamException;
33  
34  
35  /**
36   * A reusable wrapper around the antlr generated parser for an ACIItem as
37   * defined by X.501. This class enables the reuse of the antlr parser/lexer pair
38   * without having to recreate them every time.
39   * 
40   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
41   */
42  public class ACIItemChecker
43  {
44      /** the antlr generated parser being wrapped */
45      private ReusableAntlrACIItemParser checker;
46  
47      /** the antlr generated lexer being wrapped */
48      private ReusableAntlrACIItemLexer lexer;
49  
50  
51      /**
52       * Creates a ACIItem parser.
53       *
54       * @param schemaManager the schema manager
55       */
56      public ACIItemChecker( SchemaManager schemaManager )
57      {
58          this.lexer = new ReusableAntlrACIItemLexer( new StringReader( "" ) );
59          this.checker = new ReusableAntlrACIItemParser( lexer );
60          this.checker.init( schemaManager );
61      }
62  
63  
64      /**
65       * Initializes the plumbing by creating a pipe and coupling the parser/lexer
66       * pair with it. param spec the specification to be parsed
67       */
68      private synchronized void reset( String spec )
69      {
70          StringReader in = new StringReader( spec );
71          this.lexer.prepareNextInput( in );
72          this.checker.resetState();
73      }
74  
75  
76      /**
77       * Parses an ACIItem without exhausting the parser.
78       * 
79       * @param spec
80       *            the specification to be parsed
81       * @throws ParseException
82       *             if there are any recognition errors (bad syntax)
83       */
84      public synchronized void parse( String spec ) throws ParseException
85      {
86          if ( spec == null || StringConstants.EMPTY .equals( spec.trim() ) )
87          {
88              return;
89          }
90  
91          // reset and initialize the parser / lexer pair
92          reset( spec );
93  
94          try
95          {
96              this.checker.wrapperEntryPoint();
97          }
98          catch ( TokenStreamException e )
99          {
100             throw new ParseException( I18n
101                 .err( I18n.ERR_04004_PARSER_FAILURE_ACI_ITEM, spec, e.getLocalizedMessage() ), 0 );
102         }
103         catch ( RecognitionException e )
104         {
105             throw new ParseException( I18n
106                 .err( I18n.ERR_04004_PARSER_FAILURE_ACI_ITEM, spec, e.getLocalizedMessage() ), e.getColumn() );
107         }
108     }
109 
110 }