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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Rhino code, released
* May 6, 1999.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1997-1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Igor Bukanov
*
* Alternatively, the contents of this file may be used under the terms of
* the GNU General Public License Version 2 or later (the "GPL"), in which
* case the provisions of the GPL are applicable instead of those above. If
* you wish to allow use of your version of this file only under the terms of
* the GPL and not to allow others to use your version of this file under the
* MPL, indicate your decision by deleting the provisions above and replacing
* them with the notice and other provisions required by the GPL. If you do
* not delete the provisions above, a recipient may use your version of this
* file under either the MPL or the GPL.
*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.javascript;
import java.io.Serializable;
/**
* Class instances represent serializable tags to mark special Object values.
* <p>
* Compatibility note: under jdk 1.1 use
* org.mozilla.javascript.serialize.ScriptableInputStream to read serialized
* instances of UniqueTag as under this JDK version the default
* ObjectInputStream would not restore them correctly as it lacks support
* for readResolve method
*/
public final class UniqueTag implements Serializable
{
static final long serialVersionUID = -4320556826714577259L;
private static final int ID_NOT_FOUND = 1;
private static final int ID_NULL_VALUE = 2;
private static final int ID_DOUBLE_MARK = 3;
/**
* Tag to mark non-existing values.
*/
public static final UniqueTag
NOT_FOUND = new UniqueTag(ID_NOT_FOUND);
/**
* Tag to distinguish between uninitialized and null values.
*/
public static final UniqueTag
NULL_VALUE = new UniqueTag(ID_NULL_VALUE);
/**
* Tag to indicate that a object represents "double" with the real value
* stored somewhere else.
*/
public static final UniqueTag
DOUBLE_MARK = new UniqueTag(ID_DOUBLE_MARK);
private final int tagId;
private UniqueTag(int tagId)
{
this.tagId = tagId;
}
public Object readResolve()
{
switch (tagId) {
case ID_NOT_FOUND:
return NOT_FOUND;
case ID_NULL_VALUE:
return NULL_VALUE;
case ID_DOUBLE_MARK:
return DOUBLE_MARK;
}
throw new IllegalStateException(String.valueOf(tagId));
}
// Overridden for better debug printouts
public String toString()
{
String name;
switch (tagId) {
case ID_NOT_FOUND:
name = "NOT_FOUND";
break;
case ID_NULL_VALUE:
name = "NULL_VALUE";
break;
case ID_DOUBLE_MARK:
name = "DOUBLE_MARK";
break;
default:
throw Kit.codeBug();
}
return super.toString()+": "+name;
}
}
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