01: /* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
02: *
03: * ***** BEGIN LICENSE BLOCK *****
04: * Version: MPL 1.1/GPL 2.0
05: *
06: * The contents of this file are subject to the Mozilla Public License Version
07: * 1.1 (the "License"); you may not use this file except in compliance with
08: * the License. You may obtain a copy of the License at
09: * http://www.mozilla.org/MPL/
10: *
11: * Software distributed under the License is distributed on an "AS IS" basis,
12: * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13: * for the specific language governing rights and limitations under the
14: * License.
15: *
16: * The Original Code is Rhino code, released
17: * May 6, 1999.
18: *
19: * The Initial Developer of the Original Code is
20: * Netscape Communications Corporation.
21: * Portions created by the Initial Developer are Copyright (C) 1997-1999
22: * the Initial Developer. All Rights Reserved.
23: *
24: * Contributor(s):
25: * Norris Boyd
26: *
27: * Alternatively, the contents of this file may be used under the terms of
28: * the GNU General Public License Version 2 or later (the "GPL"), in which
29: * case the provisions of the GPL are applicable instead of those above. If
30: * you wish to allow use of your version of this file only under the terms of
31: * the GPL and not to allow others to use your version of this file under the
32: * MPL, indicate your decision by deleting the provisions above and replacing
33: * them with the notice and other provisions required by the GPL. If you do
34: * not delete the provisions above, a recipient may use your version of this
35: * file under either the MPL or the GPL.
36: *
37: * ***** END LICENSE BLOCK ***** */
38:
39: package org.mozilla.javascript;
40:
41: import java.io.Serializable;
42:
43: /**
44: * This class implements the Undefined value in JavaScript.
45: */
46: public class Undefined implements Serializable {
47: static final long serialVersionUID = 9195680630202616767L;
48:
49: public static final Object instance = new Undefined();
50:
51: private Undefined() {
52: }
53:
54: public Object readResolve() {
55: return instance;
56: }
57: }
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