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 literal expression.
51 *
52 * @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:44 $
53 * @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
54 * @see Expression
55 */
56 class Literal implements Expression {
57
58 /***
59 * The literal value
60 */
61 private SObject _value = null;
62
63 /***
64 * Construct a new <code>Literal</code> expression
65 *
66 * @param value the value of the literal
67 */
68 protected Literal(final SObject value) {
69 _value = value;
70 }
71
72 /***
73 * Construct an approximate numeric literal expression
74 *
75 * @param text the literal text
76 * @return an approximate numeric literal expression
77 * @throws SelectorException if <code>text</code> is not a valid
78 * approximate numeric literal
79 */
80 public static Literal approxNumericLiteral(final String text)
81 throws SelectorException {
82 SDouble value = null;
83 try {
84 value = new SDouble(Double.parseDouble(text));
85 } catch (NumberFormatException exception) {
86 throw new SelectorException("invalid float: " + text);
87 }
88 return new Literal(value);
89 }
90
91 /***
92 * Construct an exact numeric literal expression
93 *
94 * @param text the literal text
95 * @return an exact numeric literal expression
96 * @throws SelectorException if <code>text</code> is not a valid exact
97 * numeric literal
98 */
99 public static Literal exactNumericLiteral(final String text)
100 throws SelectorException {
101 SLong value = null;
102 try {
103 value = new SLong(Long.decode(text).longValue());
104 } catch (NumberFormatException exception) {
105 throw new SelectorException("invalid integer: " + text);
106 }
107 return new Literal(value);
108 }
109
110 /***
111 * Construct a string literal expression
112 *
113 * @param text the literal text
114 * @return a string literal expression
115 */
116 public static Literal stringLiteral(final String text) {
117 return new Literal(new SString(text)) {
118
119 public final String toString() {
120 return "'" + this.getValue().toString() + "'";
121 }
122 };
123 }
124
125 /***
126 * Construct a boolean literal expression
127 *
128 * @param value the boolean literal value
129 * @return a boolean literal expression
130 */
131 public static Literal booleanLiteral(final boolean value) {
132 SBool bool = SBool.FALSE;
133 if (value) {
134 bool = SBool.TRUE;
135 }
136 return new Literal(bool);
137 }
138
139 /***
140 * Evaluate the expression
141 *
142 * @param msg the message to use to obtain any header identifier and
143 * property values
144 * @return the evaluated result, or <code>null</code> if the value of the
145 * expression is unknown
146 */
147 public final SObject evaluate(final Message msg) {
148 return _value;
149 }
150
151 /***
152 * Return a string representation of the literal
153 *
154 * @return a string representation of the literal
155 */
156 public String toString() {
157 return getValue().toString();
158 }
159
160 /***
161 * Returns the value of the literal
162 *
163 * @return the value of the literal
164 */
165 protected final SObject getValue() {
166 return _value;
167 }
168
169 }