Source/JavaScriptCore/runtime/StructureChain.h

/*
 * Copyright (C) 2008-2022 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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 *    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
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#pragma once

#include "JSCast.h"
#include "JSObject.h"
#include "Structure.h"
#include <wtf/StdLibExtras.h>
#include <wtf/UniqueArray.h>

namespace JSC {

class LLIntOffsetsExtractor;
class Structure;

class StructureChain final : public JSCell {
    friend class JIT;

public:
    using Base = JSCell;
    static constexpr unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;

    template<typename CellType, SubspaceAccess>
    static GCClient::IsoSubspace* subspaceFor(VM& vm)
    {
        return &vm.structureChainSpace();
    }

    static StructureChain* create(VM&, JSObject*);
    StructureID* head() { return m_vector.get(); }
    DECLARE_VISIT_CHILDREN;

    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
    {
        return Structure::create(vm, globalObject, prototype, TypeInfo(CellType, StructureFlags), info());
    }

    DECLARE_INFO;

private:
    friend class LLIntOffsetsExtractor;

    void finishCreation(VM&, JSObject* head);

    StructureChain(VM&, Structure*, StructureID*);
    AuxiliaryBarrier<StructureID*> m_vector;
};

} // namespace JSC