Selector


1   /*
2    * JORAM: Java(TM) Open Reliable Asynchronous Messaging
3    * Copyright (C) 2001 - 2004 ScalAgent Distributed Technologies
4    * Copyright (C) 1996 - 2000 Dyade
5    *
6    * This library is free software; you can redistribute it and/or
7    * modify it under the terms of the GNU Lesser General Public
8    * License as published by the Free Software Foundation; either
9    * version 2.1 of the License, or any later version.
10   * 
11   * This library is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   * Lesser General Public License for more details.
15   * 
16   * You should have received a copy of the GNU Lesser General Public
17   * License along with this library; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
19   * USA.
20   *
21   * Initial developer(s): Frederic Maistre (INRIA)
22   * Contributor(s):  ScalAgent Distributed Technologies
23   */
24  package org.objectweb.joram.shared.selectors;
25  
26  import org.objectweb.joram.shared.excepts.SelectorException;
27  import org.objectweb.joram.shared.messages.Message;
28  
29  /**
30   * The <code>Selector</code> class is used for filtering messages according
31   * to their header fields and properties.
32   */
33  public class Selector
34  {
35    /**
36     * Clients call this method to check a selector syntax.
37     *
38     * @return  <code>true</code> when the syntax is ok.
39     * @exception SelectorException  When the selector syntax is incorrect.
40     */
41    public static boolean checks(String   selector) throws SelectorException
42    {
43      if (selector == null || selector.equals(""))
44        return true;
45  
46      try {
47        Checker checker = new Checker(new Lexer(selector));
48        return ((Boolean  ) checker.parse().value).booleanValue();
49      }
50      catch (SelectorException sE) {
51        throw sE;
52      }
53      catch (Throwable   t) {
54        throw new SelectorException("Invalid selector: " + t.getMessage());
55      }
56    }
57  
58    /**
59     * Destinations call this method to filter a message according to a selector.
60     *
61     * @return  <code>true</code> when the selection matches, <code>false</code>
62     *          otherwise.
63     */
64    public static boolean matches(Message message, String   selector)
65    {
66      if (selector == null || selector.equals(""))
67        return true;
68  
69      try {
70        Filter filter = new Filter(new Lexer(selector), message, "JMS");
71        Boolean   result = (Boolean  ) filter.parse().value;
72  
73        if (result == null)
74          return false;
75      
76        return result.booleanValue();
77      }
78      catch (Throwable   t) {
79        return false;
80      }
81    }
82  }
83    
84
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