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/*
* Copyright (C) 2015-2024 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "ArgumentsMode.h"
#include "JSObject.h"
namespace JSC {
// This is an Arguments-class object that we create when you do function.arguments, or you say
// "arguments" inside a function in strict mode. It behaves almpst entirely like an ordinary
// JavaScript object. All of the arguments values are simply copied from the stack (possibly via
// some sophisticated ValueRecovery's if an optimizing compiler is in play) and the appropriate
// properties of the object are populated. The only reason why we need a special class is to make
// the object claim to be "Arguments" from a toString standpoint, and to avoid materializing the
// caller/callee/@@iterator properties unless someone asks for them.
static constexpr PropertyOffset clonedArgumentsLengthPropertyOffset = firstOutOfLineOffset;
class ClonedArguments final : public JSNonFinalObject {
public:
using Base = JSNonFinalObject;
static constexpr unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetOwnSpecialPropertyNames | OverridesPut;
template<typename CellType, SubspaceAccess mode>
static GCClient::IsoSubspace* subspaceFor(VM& vm)
{
static_assert(CellType::needsDestruction == DoesNotNeedDestruction);
return &vm.clonedArgumentsSpace();
}
uint64_t length(JSGlobalObject* globalObject) const
{
VM& vm = getVM(globalObject);
auto scope = DECLARE_THROW_SCOPE(vm);
JSValue lengthValue;
if (LIKELY(!structure()->didTransition())) {
lengthValue = getDirect(clonedArgumentsLengthPropertyOffset);
if (LIKELY(lengthValue.isInt32()))
return std::max(lengthValue.asInt32(), 0);
} else {
lengthValue = get(globalObject, vm.propertyNames->length);
RETURN_IF_EXCEPTION(scope, 0);
}
RELEASE_AND_RETURN(scope, lengthValue.toLength(globalObject));
}
void copyToArguments(JSGlobalObject*, JSValue* firstElementDest, unsigned offset, unsigned length);
JS_EXPORT_PRIVATE bool isIteratorProtocolFastAndNonObservable();
private:
ClonedArguments(VM&, Structure*, Butterfly*);
public:
static ClonedArguments* createEmpty(VM&, JSGlobalObject* nullOrGlobalObjectForOOM, Structure*, JSFunction* callee, unsigned length, Butterfly*);
static ClonedArguments* createWithInlineFrame(JSGlobalObject*, CallFrame* targetFrame, InlineCallFrame*, ArgumentsMode);
static ClonedArguments* createWithMachineFrame(JSGlobalObject*, CallFrame* targetFrame, ArgumentsMode);
static ClonedArguments* createByCopyingFrom(JSGlobalObject*, Structure*, Register* argumentsStart, unsigned length, JSFunction* callee, Butterfly*);
static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
static Structure* createSlowPutStructure(VM&, JSGlobalObject*, JSValue prototype);
static constexpr ptrdiff_t offsetOfCallee()
{
return OBJECT_OFFSETOF(ClonedArguments, m_callee);
}
static size_t allocationSize(Checked<size_t> inlineCapacity)
{
ASSERT_UNUSED(inlineCapacity, !inlineCapacity);
return sizeof(ClonedArguments);
}
DECLARE_VISIT_CHILDREN;
DECLARE_INFO;
private:
static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype, IndexingType);
static bool getOwnPropertySlot(JSObject*, JSGlobalObject*, PropertyName, PropertySlot&);
static void getOwnSpecialPropertyNames(JSObject*, JSGlobalObject*, PropertyNameArray&, DontEnumPropertiesMode);
static bool put(JSCell*, JSGlobalObject*, PropertyName, JSValue, PutPropertySlot&);
static bool deleteProperty(JSCell*, JSGlobalObject*, PropertyName, DeletePropertySlot&);
static bool defineOwnProperty(JSObject*, JSGlobalObject*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
bool specialsMaterialized() const { return !m_callee; }
void materializeSpecials(JSGlobalObject*);
void materializeSpecialsIfNecessary(JSGlobalObject*);
WriteBarrier<JSFunction> m_callee; // Set to nullptr when we materialize all of our special properties.
};
} // namespace JSC
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