1/*
2 * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include "ArgumentsMode.h"
29#include "JSObject.h"
30
31namespace JSC {
32
33// This is an Arguments-class object that we create when you do function.arguments, or you say
34// "arguments" inside a function in strict mode. It behaves almpst entirely like an ordinary
35// JavaScript object. All of the arguments values are simply copied from the stack (possibly via
36// some sophisticated ValueRecovery's if an optimizing compiler is in play) and the appropriate
37// properties of the object are populated. The only reason why we need a special class is to make
38// the object claim to be "Arguments" from a toString standpoint, and to avoid materializing the
39// caller/callee/@@iterator properties unless someone asks for them.
40class ClonedArguments final : public JSNonFinalObject {
41public:
42 typedef JSNonFinalObject Base;
43 static const unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetPropertyNames;
44
45private:
46 ClonedArguments(VM&, Structure*, Butterfly*);
47
48public:
49 static ClonedArguments* createEmpty(VM&, Structure*, JSFunction* callee, unsigned length);
50 static ClonedArguments* createEmpty(ExecState*, JSFunction* callee, unsigned length);
51 static ClonedArguments* createWithInlineFrame(ExecState* myFrame, ExecState* targetFrame, InlineCallFrame*, ArgumentsMode);
52 static ClonedArguments* createWithMachineFrame(ExecState* myFrame, ExecState* targetFrame, ArgumentsMode);
53 static ClonedArguments* createByCopyingFrom(ExecState*, Structure*, Register* argumentsStart, unsigned length, JSFunction* callee);
54
55 static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
56 static Structure* createSlowPutStructure(VM&, JSGlobalObject*, JSValue prototype);
57
58 static void visitChildren(JSCell*, SlotVisitor&);
59
60 DECLARE_INFO;
61
62private:
63 static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype, IndexingType);
64
65 static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
66 static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
67 static bool put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
68 static bool deleteProperty(JSCell*, ExecState*, PropertyName);
69 static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
70
71 bool specialsMaterialized() const { return !m_callee; }
72 void materializeSpecials(ExecState*);
73 void materializeSpecialsIfNecessary(ExecState*);
74
75 WriteBarrier<JSFunction> m_callee; // Set to nullptr when we materialize all of our special properties.
76};
77
78static const PropertyOffset clonedArgumentsLengthPropertyOffset = 100;
79
80} // namespace JSC
81