PrototypeObject.java revision 1416:a750a66640e0 
1/*
2 * Copyright (c) 2010, 2013, 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 static jdk.nashorn.internal.lookup.Lookup.MH;
29import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;
30
31import java.lang.invoke.MethodHandle;
32import java.lang.invoke.MethodHandles;
33import java.util.ArrayList;
34import jdk.nashorn.internal.objects.Global;
35
36/**
37 * Instances of this class serve as "prototype" object for script functions.
38 * The purpose is to expose "constructor" property from "prototype". Also, nasgen
39 * generated prototype classes extend from this class.
40 */
41public class PrototypeObject extends ScriptObject {
42    private static final PropertyMap map$;
43
44    private Object constructor;
45
46    private static final MethodHandle GET_CONSTRUCTOR = findOwnMH("getConstructor", Object.class, Object.class);
47    private static final MethodHandle SET_CONSTRUCTOR = findOwnMH("setConstructor", void.class, Object.class, Object.class);
48
49    static {
50        final ArrayList<Property> properties = new ArrayList<>(1);
51        properties.add(AccessorProperty.create("constructor", Property.NOT_ENUMERABLE, GET_CONSTRUCTOR, SET_CONSTRUCTOR));
52        map$ = PropertyMap.newMap(properties);
53    }
54
55    private PrototypeObject(final Global global, final PropertyMap map) {
56        super(global.getObjectPrototype(), map != map$? map.addAll(map$) : map$);
57    }
58
59    /**
60     * Prototype constructor
61     */
62    protected PrototypeObject() {
63        this(Global.instance(), map$);
64    }
65
66    /**
67     * PropertyObject constructor
68     *
69     * @param map property map
70     */
71    protected PrototypeObject(final PropertyMap map) {
72        this(Global.instance(), map);
73    }
74
75    /**
76     * PropertyObject constructor
77     *
78     * @param func constructor function
79     */
80    protected PrototypeObject(final ScriptFunction func) {
81        this(Global.instance(), map$);
82        this.constructor = func;
83    }
84
85    /**
86     * Get the constructor for this {@code PrototypeObject}
87     * @param self self reference
88     * @return constructor, probably, but not necessarily, a {@link ScriptFunction}
89     */
90    public static Object getConstructor(final Object self) {
91        return (self instanceof PrototypeObject) ?
92            ((PrototypeObject)self).getConstructor() :
93            UNDEFINED;
94    }
95
96    /**
97     * Reset the constructor for this {@code PrototypeObject}
98     * @param self self reference
99     * @param constructor constructor, probably, but not necessarily, a {@link ScriptFunction}
100     */
101    public static void setConstructor(final Object self, final Object constructor) {
102        if (self instanceof PrototypeObject) {
103            ((PrototypeObject)self).setConstructor(constructor);
104        }
105    }
106
107    private Object getConstructor() {
108        return constructor;
109    }
110
111    private void setConstructor(final Object constructor) {
112        this.constructor = constructor;
113    }
114
115    private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {
116        return MH.findStatic(MethodHandles.lookup(), PrototypeObject.class, name, MH.type(rtype, types));
117    }
118}
119