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Java > Open Source Codes > com > caucho > quercus > env > NullThisValue


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  *
23  * Free Software Foundation, Inc.
24  * 59 Temple Place, Suite 330
25  * Boston, MA 02111-1307 USA
26  *
27  * @author Scott Ferguson
28  */

29
30 package com.caucho.quercus.env;
31
32 import java.io.Serializable JavaDoc;
33
34 import com.caucho.quercus.QuercusException;
35
36 /**
37  * Represents a PHP null value.
38  */

39 public class NullThisValue extends NullValue
40   implements Serializable JavaDoc
41 {
42   public static final NullThisValue NULL = new NullThisValue();
43
44   protected NullThisValue()
45   {
46   }
47
48   /**
49    * Returns the null value singleton.
50    */

51   public static NullThisValue create()
52   {
53     return NULL;
54   }
55
56   /**
57    * Evaluates a method.
58    */

59   public Value callMethod(Env env, String JavaDoc methodName, Value []args)
60   {
61     throw new QuercusException(L.l("$this value of NULL cannot dispatch to method '{0}'.", methodName));
62   }
63   
64   //
65
// Java Serialization
66
//
67

68   private Object JavaDoc readResolve()
69   {
70     return NULL;
71   }
72 }
73
74
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