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
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 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 <> 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 <> 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 < obj</code>, otherwise
110 * <code>SBool.FALSE</code> if <code>this >= 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 > obj</code>, otherwise
122 * <code>SBool.FALSE</code> if <code>this <= 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 <= obj</code>, otherwise
134 * <code>SBool.FALSE</code> if <code>this > 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 >= obj</code>, otherwise
150 * <code>SBool.FALSE</code> if <code>this < 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 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 }