/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * The contents of this file are subject to the Netscape 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/NPL/ * * Software distributed under the License is distributed on an "AS * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express oqr * 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 Netscape are * Copyright (C) 1997-1999 Netscape Communications Corporation. All * Rights Reserved. * * Contributor(s): * Igor Bukanov * * Alternatively, the contents of this file may be used under the * terms of the GNU Public License (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 NPL, indicate your decision by * deleting the provisions above and replace 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 NPL or the GPL. */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;    }}