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;
47
48
49 /***
50 * This class implements a unary minus operator.
51 *
52 * @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:45 $
53 * @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
54 * @see Expression
55 * @see SNumber
56 * @see UnaryOperator
57 */
58 class UnaryMinus extends UnaryOperator {
59
60 /***
61 * The expression context, for error reporting purposes
62 */
63 private static final String CONTEXT = "unary minus";
64
65 /***
66 * Helper for -1
67 */
68 private static final SLong MINUS1 = new SLong(-1);
69
70 /***
71 * Construct a new <code>UnaryMinus</code> operator
72 *
73 * @param operand the operand
74 */
75 public UnaryMinus(final Expression operand) {
76 super("-", operand);
77 }
78
79 /***
80 * Evaluate the expression
81 *
82 * @param msg the message to evaluate this expression against
83 * @return the result of expression
84 * @throws TypeMismatchException if the operand doesn't evaluate to
85 * a numeric or null
86 */
87 public final SObject evaluate(final Message msg)
88 throws TypeMismatchException {
89 SObject result = null;
90 SNumber value = TypeCaster.castToNumber(operand().evaluate(msg),
91 CONTEXT);
92 if (value != null) {
93 result = value.multiply(MINUS1);
94 }
95 return result;
96 }
97
98 }