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