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Java > Open Source Codes > org > mr > api > jms > selector > syntax > Not


1 /*
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7  * 1.1 (the "License"); you may not use this file except in compliance with the
8  * License. You may obtain a copy of the License at
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16  * The Original Code is "MantaRay" (TM).
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46 package org.mr.api.jms.selector.syntax;
47
48 import javax.jms.Message JavaDoc;
49
50
51 /**
52  * This class implements a 'not' operator.
53  *
54  */
55 class Not extends UnaryOperator {
56
57     /**
58      * The expression context, for error reporting purposes
59      */
60     private static final String JavaDoc CONTEXT = "not operator";
61
62
63     /**
64      * Construct a new Not operator
65      *
66      * @param operand the operand
67      */
68     public Not(final Expression operand) {
69         super("not", operand);
70     }//Not
71
72     
73     /**
74      * Evaluate the expression
75      *
76      * @param msg the message to evaluate this expression against
77      * @return the result of expression
78      * @throws TypeMismatchException if the operand doesn't evaluate to
79      * a boolean or null
80      */
81     public MantaObject evaluate(final Message JavaDoc msg) throws TypeMismatchException {
82     
83         MantaBoolean result = null;
84         MantaBoolean value = TypeCaster.castToBool(operand().evaluate(msg), CONTEXT);
85         
86         if (value != null) {
87             result = value.not();
88         }//if
89 return result;
90     }//evaluate
91 }//Not
92
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