KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > caucho > jms > selector > UnarySelector


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free SoftwareFoundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.jms.selector;
30
31 import com.caucho.util.L10N;
32
33 import javax.jms.JMSException JavaDoc;
34 import javax.jms.Message JavaDoc;
35
36 /**
37  * The base selector.
38  */
39 public class UnarySelector extends Selector {
40   static L10N L = new L10N(Selector.class);
41
42   private int _token;
43   private Selector _expr;
44
45   UnarySelector(int token, Selector expr)
46   {
47     _token = token;
48     _expr = expr;
49   }
50
51   boolean isBoolean()
52   {
53     switch (_token) {
54     case SelectorParser.NOT:
55     case SelectorParser.NULL:
56       return true;
57     }
58     
59     return false;
60   }
61
62   boolean isNumber()
63   {
64     switch (_token) {
65     case '-':
66     case '+':
67       return true;
68     }
69     
70     return false;
71   }
72
73   boolean isUnknown()
74   {
75     return false;
76   }
77
78   /**
79    * Evaluate the message. The boolean literal selector returns
80    * the value of the boolean.
81    */
82   Object JavaDoc evaluate(Message JavaDoc message)
83     throws JMSException JavaDoc
84   {
85     Object JavaDoc value = _expr.evaluate(message);
86     
87     switch (_token) {
88     case SelectorParser.NOT:
89       if (! (value instanceof Boolean JavaDoc))
90         return NULL;
91       else
92         return toBoolean(! ((Boolean JavaDoc) value).booleanValue());
93       
94     case SelectorParser.NULL:
95       return toBoolean(value == null);
96       
97     case '+':
98       if (! (value instanceof Number JavaDoc))
99         return NULL;
100       else
101         return value;
102       
103     case '-':
104       if (! (value instanceof Number JavaDoc))
105         return NULL;
106       else if (isInteger(value))
107         return new Long JavaDoc(- toLong(value));
108       else
109         return new Double JavaDoc(- ((Number JavaDoc) value).doubleValue());
110       
111     default:
112       throw new JMSException JavaDoc("NOTONE");
113     }
114   }
115 }
116
Popular Tags