KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > exolab > jms > selector > LikeExpression


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;
45
46 import javax.jms.Message JavaDoc;
47
48 import org.apache.oro.text.regex.Pattern;
49 import org.apache.oro.text.regex.PatternMatcher;
50 import org.apache.oro.text.regex.Perl5Matcher;
51
52
53 /**
54  * This class implements a 'like' expression.
55  * This is an expression that returns true if a identifier's value matches
56  * a pattern
57  *
58  * @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:44 $
59  * @author <a HREF="mailto:tma@netspace.net.au">Tim Anderson</a>
60  * @see Identifier
61  * @see IdentifierExpression
62  * @see RegexpFactory
63  */
64 class LikeExpression extends IdentifierExpression {
65
66     /**
67      * The regular expression
68      */
69     private final Pattern _regexp;
70
71     /**
72      * The pattern matcher
73      */
74     private final PatternMatcher _matcher;
75
76     /**
77      * The pattern
78      */
79     private final String JavaDoc _pattern;
80
81     /**
82      * The escape character. May be null.
83      */
84     private final String JavaDoc _escape;
85
86
87     /**
88      * Construct a new <code>LikeExpression</code>
89      *
90      * @param identifier the identifier
91      * @param pattern the pattern
92      * @param escape the escape character. May be null.
93      * @throws SelectorException if <code>pattern</code> or <code>escape</code>
94      * are invalid
95      */
96     public LikeExpression(final Identifier identifier, final String JavaDoc pattern,
97                           final String JavaDoc escape) throws SelectorException {
98         super(identifier);
99         _pattern = pattern;
100         _escape = escape;
101         _regexp = getRegexp(_pattern, _escape);
102         _matcher = new Perl5Matcher();
103     }
104
105     /**
106      * Evaluate the expression
107      *
108      * @param msg the message to use to obtain any header identifier and
109      * property values
110      * @return the evaluated result, or <code>null</code> if the value of the
111      * expression is unknown
112      * @throws TypeMismatchException if the expression tries to evaluate
113      * mismatched types.
114      */
115     public final SObject evaluate(final Message JavaDoc msg)
116         throws TypeMismatchException {
117         SBool result = null;
118         SString value = TypeCaster.castToString(identifier().evaluate(msg),
119             "like expression");
120         if (value != null) {
121             if (_matcher.matches((String JavaDoc) value.getObject(), _regexp)) {
122                 result = SBool.TRUE;
123             } else {
124                 result = SBool.FALSE;
125             }
126         }
127         return result;
128     }
129
130     /**
131      * Return a string representation of this expression.
132      *
133      * @return a string representation of this expression
134      */
135     public final String JavaDoc toString() {
136         StringBuffer JavaDoc result = new StringBuffer JavaDoc();
137         result.append('(');
138         result.append(identifier().toString());
139         result.append(" like '");
140         result.append(_pattern);
141         result.append('\'');
142         if (_escape != null) {
143             result.append(" escape '");
144             result.append(_escape);
145             result.append('\'');
146         }
147         result.append(')');
148         return result.toString();
149     }
150
151     /**
152      * Converts the pattern and escape to an ORO <code>Pattern</code>
153      *
154      * @param pattern the pattern
155      * @param escape the escape character. May be null
156      * @return an ORO <code>Pattern</code> corresponding to
157      * <code>pattern</code> and <code>escape</code>
158      * @throws SelectorException if <code>pattern</code> or <code>escape</code>
159      * are invalid
160      */
161     private Pattern getRegexp(final String JavaDoc pattern, final String JavaDoc escape)
162         throws SelectorException {
163         Pattern result = null;
164         Character JavaDoc esc = null;
165
166         if (escape != null) {
167             if (escape.length() != 1) {
168                 throw new SelectorException("Invalid escape: " + escape);
169             }
170             esc = new Character JavaDoc(escape.charAt(0));
171         }
172
173         try {
174             result = RegexpFactory.create(pattern, esc);
175         } catch (InvalidRegexpException err) {
176             throw new SelectorException("Invalid pattern: " + pattern);
177         }
178         return result;
179     }
180
181 } //-- LikeExpression
182
Popular Tags