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Java > Open Source Codes > org > exolab > jms > selector > parser > PatternValidator


1 /**
2  * Redistribution and use of this software and associated documentation
3  * ("Software"), with or without modification, are permitted provided
4  * that the following conditions are met:
5  *
6  * 1. Redistributions of source code must retain copyright
7  * statements and notices. Redistributions must also contain a
8  * copy of this document.
9  *
10  * 2. Redistributions in binary form must reproduce the
11  * above copyright notice, this list of conditions and the
12  * following disclaimer in the documentation and/or other
13  * materials provided with the distribution.
14  *
15  * 3. The name "Exolab" must not be used to endorse or promote
16  * products derived from this Software without prior written
17  * permission of Exoffice Technologies. For written permission,
18  * please contact info@exolab.org.
19  *
20  * 4. Products derived from this Software may not be called "Exolab"
21  * nor may "Exolab" appear in their names without prior written
22  * permission of Exoffice Technologies. Exolab is a registered
23  * trademark of Exoffice Technologies.
24  *
25  * 5. Due credit should be given to the Exolab Project
26  * (http://www.exolab.org/).
27  *
28  * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
32  * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39  * OF THE POSSIBILITY OF SUCH DAMAGE.
40  *
41  * Copyright 2000-2001,2003 (C) Exoffice Technologies Inc. All Rights Reserved.
42  */
43
44 package org.exolab.jms.selector.parser;
45
46 import org.exolab.jms.selector.SelectorException;
47
48
49 /**
50  * This class validates the format of patterns and escape characters used
51  * in 'like' expressions.
52  *
53  * @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:45 $
54  * @author <a HREF="mailto:tma@netspace.net.au">Tim Anderson</a>
55  * @see SelectorAST
56  * @see SelectorParser
57  */
58 final class PatternValidator {
59
60     /**
61      * Private constructor
62      */
63     private PatternValidator() {
64     }
65
66     /**
67      * Validate a pattern and escape
68      *
69      * @param patternNode the pattern node
70      * @param escapeNode the escape node. May be null.
71      * @throws SelectorException if the pattern or escape node are invalid
72      */
73     public static void validate(final SelectorAST patternNode,
74                                 final SelectorAST escapeNode)
75         throws SelectorException {
76
77         String JavaDoc pattern = patternNode.getText();
78
79         if (escapeNode != null) {
80             String JavaDoc escape = escapeNode.getText();
81             if (escape.length() != 1) {
82                 String JavaDoc msg = "escape must be a single character";
83                 throw new SelectorException(escapeNode.getContext(), msg);
84             }
85
86             char esc = escape.charAt(0);
87             for (int i = 0; i < pattern.length(); ++i) {
88                 char ch = pattern.charAt(i);
89                 if (pattern.charAt(i) == esc) {
90                     if (++i >= pattern.length()) {
91                         String JavaDoc msg = "invalid pattern: no character "
92                             + "following last escape character";
93                         throw new SelectorException(patternNode.getContext(),
94                                                     msg);
95                     }
96                 }
97             }
98         }
99     }
100
101 } //-- PatternValidator
102
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