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Java > Open Source Codes > org > mr > api > jms > selector > syntax > And


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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14  * License.
15  *
16  * The Original Code is "MantaRay" (TM).
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18  * The Initial Developer of the Original Code is Coridan.
19  * Portions created by the Initial Developer are Copyright (C) 2006
20  * Coridan Inc. All Rights Reserved.
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25  * Alternatively, the contents of this file may be used under the terms of the
26  * LGPL license (the "GNU LESSER GENERAL PUBLIC LICENSE"), in which case the
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38  * Lesser General Public License as published by the Free Software Foundation;
39  * either version 2.1 of the License, or any later version.
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41  * This library is distributed in the hope that it will be useful, but WITHOUT
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45  */
46 package org.mr.api.jms.selector.syntax;
47
48 import javax.jms.Message JavaDoc;
49
50
51 /**
52  * This class implements an 'and' expression.
53  *
54  */
55 class And extends LogicalOperator {
56
57     /**
58      * The expression context, for error reporting purposes
59      */
60     private static final String JavaDoc CONTEXT = "and operator";
61
62
63     /**
64      * Construct a new And operator
65      *
66      * @param leftHand the left hand side of the expression
67      * @param rightHand the right hand side of the expression
68      */
69     public And(final Expression leftHand, final Expression rightHand) {
70         super("and", leftHand, rightHand);
71     }//And
72
73
74     /**
75      * Evaluate the expression
76      *
77      * @param msg the message to use to obtain any header identifier and
78      * property values
79      * @return the evaluated result, or null if the value of the
80      * expression is unknown
81      * @throws TypeMismatchException if the expression tries to evaluate
82      * mismatched types.
83      */
84     public final MantaObject evaluate(final Message JavaDoc msg) throws TypeMismatchException {
85     
86         MantaBoolean result = null;
87         MantaBoolean leftHand = TypeCaster.castToBool(left().evaluate(msg), CONTEXT);
88         if (leftHand!= null) {
89             if (!leftHand.value()) {
90                 result = MantaBoolean.FALSE;
91             } //if
92 else {
93                 MantaBoolean rightHand= TypeCaster.castToBool(right().evaluate(msg), CONTEXT);
94                 result = leftHand.and(rightHand);
95             }//else
96 }//if
97 else {
98             MantaBoolean rightHand= TypeCaster.castToBool(right().evaluate(msg), CONTEXT);
99             if (rightHand!= null) {
100                 result = rightHand.and(leftHand);
101             }//if
102 }//else
103 return result;
104     }//evaluate
105 }//And
106
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