1/*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package jdk.nashorn.internal.runtime;
27
28import java.io.Serializable;
29import jdk.nashorn.internal.objects.NativeSymbol;
30
31/**
32 * This class represents a unique, non-String Object property key as defined in ECMAScript 6.
33 */
34public final class Symbol implements Serializable {
35
36    private final String name;
37
38    private static final long serialVersionUID = -2988436597549486913L;
39
40    /**
41     * Symbol constructor
42     * @param name symbol name
43     */
44    public Symbol(final String name) {
45        this.name = name;
46    }
47
48    @Override
49    public String toString() {
50        return "Symbol(" + name + ")";
51    }
52
53    /**
54     * Return the symbol's name
55     * @return the name
56     */
57    public final String getName() {
58        return name;
59    }
60
61    private Object writeReplace() {
62        // If this symbol is a globally registered one, replace it with a
63        // GlobalSymbol in serialized stream.
64        return NativeSymbol.keyFor(null, this) == name ? new GlobalSymbol(name) : this;
65    }
66
67    /**
68     * Represents a globally registered (with NativeSymbol._for) symbol in the
69     * serialized stream. Upon deserialization, it resolves to the globally
70     * registered symbol.
71     */
72    private static class GlobalSymbol implements Serializable {
73        private static final long serialVersionUID = 1L;
74
75        private final String name;
76
77        GlobalSymbol(final String name) {
78            this.name = name;
79        }
80
81        private Object readResolve() {
82            return NativeSymbol._for(null, name);
83        }
84    }
85}
86