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


1 /**
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3  * ("Software"), with or without modification, are permitted provided
4  * that the following conditions are met:
5  *
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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
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14  *
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16  * products derived from this Software without prior written
17  * permission of Exoffice Technologies. For written permission,
18  * please contact info@exolab.org.
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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
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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
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37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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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
47 /**
48  * This class is the base class for classes adapting simple Java types.
49  * This is necessary to:
50  * <ul>
51  * <li>reduce the number of types that the selector has to deal with.
52  * Expressions only evaluate to boolean, numeric and string types.
53  * </li>
54  * <li>Simplify operations (comparison, type checking etc.) on these types.
55  * </li>
56  * </ul>
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 Expression
61  * @see SObjectFactory
62  */
63 abstract class SObject {
64
65     /**
66      * Returns the underlying object
67      *
68      * @return the underlying object
69      */
70     public abstract Object JavaDoc getObject();
71
72     /**
73      * Determines if this is equal to another object.
74      *
75      * @param obj the object to compare
76      * @return <code>null</code> if the comparison is undefined,
77      * <code>SBool.TRUE</code> if <code>this = obj</code>, otherwise
78      * <code>SBool.FALSE</code> if <code>this &lt;&gt; obj</code>
79      */
80     public SBool equal(final SObject obj) {
81         SBool result = SBool.FALSE;
82         if (getObject().equals(obj.getObject())) {
83             result = SBool.TRUE;
84         }
85         return result;
86     }
87
88     /**
89      * Determines if this is not equal to another object
90      *
91      * @param obj the object to compare
92      * @return <code>null</code> if the comparison is undefined,
93      * <code>SBool.TRUE</code> if <code>this &lt;&gt; obj</code>, otherwise
94      * <code>SBool.FALSE</code> if <code>this = obj</code>
95      */
96     public SBool notEqual(final SObject obj) {
97         SBool result = equal(obj);
98         if (result != null) {
99             result = result.not();
100         }
101         return result;
102     }
103
104     /**
105      * Determines if this is less than another object.
106      *
107      * @param obj the object to compare
108      * @return <code>null</code> if the comparison is undefined,
109      * <code>SBool.TRUE</code> if <code>this &lt; obj</code>, otherwise
110      * <code>SBool.FALSE</code> if <code>this &gt;= obj</code>
111      */
112     public SBool less(final SObject obj) {
113         return null;
114     }
115
116     /**
117      * Determines if this is greater than another object.
118      *
119      * @param obj the object to compare
120      * @return <code>null</code> if the comparison is undefined,
121      * <code>SBool.TRUE</code> if <code>this &gt; obj</code>, otherwise
122      * <code>SBool.FALSE</code> if <code>this &lt;= obj</code>
123      */
124     public SBool greater(final SObject obj) {
125         return null;
126     }
127
128     /**
129      * Determines if this is less than or equal to another object.
130      *
131      * @param obj the object to compare
132      * @return <code>null</code> if the comparison is undefined,
133      * <code>SBool.TRUE</code> if <code>this &lt;= obj</code>, otherwise
134      * <code>SBool.FALSE</code> if <code>this &gt; obj</code>
135      */
136     public SBool lessEqual(final SObject obj) {
137         SBool result = less(obj);
138         if (result != null && !result.value()) {
139             result = equal(obj);
140         }
141         return result;
142     }
143
144     /**
145      * Determines if this is greater than or equal to another object.
146      *
147      * @param obj the object to compare
148      * @return <code>null</code> if the comparison is undefined,
149      * <code>SBool.TRUE</code> if <code>this &gt;= obj</code>, otherwise
150      * <code>SBool.FALSE</code> if <code>this &lt; obj</code>
151      */
152     public SBool greaterEqual(final SObject obj) {
153         SBool result = greater(obj);
154         if (result != null && !result.value()) {
155             result = equal(obj);
156         }
157         return result;
158     }
159
160     /**
161      * Returns a string representation of this
162      *
163      * @return a string representation of this
164      */
165     public String JavaDoc toString() {
166         return getObject().toString();
167     }
168
169     /**
170      * Determines the type of this
171      *
172      * @return the type of this
173      */
174     public abstract Type type();
175
176 } //-- SObject
177
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