Source/JavaScriptCore/runtime/JSPromiseReaction.h

/*
 * Copyright (C) 2025 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
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#pragma once

#include "JSInternalFieldObjectImpl.h"
#include "Microtask.h"
#include <wtf/CompactPointerTuple.h>

namespace JSC {
class JSPromiseReaction;
}
WTF_ALLOW_COMPACT_POINTERS_TO_INCOMPLETE_TYPE(JSC::JSPromiseReaction);

namespace JSC {

class JSPromiseReaction : public JSCell {
public:
    using Base = JSCell;

    DECLARE_EXPORT_INFO;
    DECLARE_VISIT_CHILDREN;

    JSValue promise() const { return m_promise.get(); }
    JSPromiseReaction* next() const LIFETIME_BOUND { return m_next.pointer(); }
    InternalMicrotask internalMicrotask() const { return static_cast<InternalMicrotask>(m_next.type()); }

    void setPromise(VM& vm, JSValue value) { m_promise.set(vm, this, value); }
    void setNext(VM& vm, JSPromiseReaction* value)
    {
        m_next.setPointer(value);
        vm.writeBarrier(this, value);
    }

    static JSValue tryGetContext(JSValue reactionsValue);

protected:
    JSPromiseReaction(VM& vm, Structure* structure, JSValue promise, JSPromiseReaction* next, InternalMicrotask task = InternalMicrotask::None)
        : Base(vm, structure)
        , m_promise(promise, WriteBarrierEarlyInit)
        , m_next(next, static_cast<uint8_t>(task))
    {
    }

    WriteBarrier<Unknown> m_promise;
    CompactPointerTuple<JSPromiseReaction*, uint8_t> m_next;
};

class JSSlimPromiseReaction final : public JSPromiseReaction {
public:
    using Base = JSPromiseReaction;

    DECLARE_EXPORT_INFO;
    DECLARE_VISIT_CHILDREN;

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

    static Structure* createStructure(VM&, JSGlobalObject*, JSValue);

    static JSSlimPromiseReaction* create(VM&, JSValue promise, JSValue handler, bool isFulfill, JSPromiseReaction* next);
    static JSSlimPromiseReaction* create(VM&, JSValue promise, InternalMicrotask, JSValue context, JSPromiseReaction* next);

    bool isFulfillHandler() const { return perCellBit(); }

    JSValue handlerOrContext() const { return m_handlerOrContext.get(); }
    void setHandlerOrContext(VM& vm, JSValue value) { m_handlerOrContext.set(vm, this, value); }

private:
    JSSlimPromiseReaction(VM& vm, Structure* structure, JSValue promise, JSValue handlerOrContext, JSPromiseReaction* next, InternalMicrotask task, bool isFulfill)
        : Base(vm, structure, promise, next, task)
        , m_handlerOrContext(handlerOrContext, WriteBarrierEarlyInit)
    {
        if (isFulfill)
            setPerCellBit(true);
    }

    WriteBarrier<Unknown> m_handlerOrContext;
};

class JSFullPromiseReaction final : public JSPromiseReaction {
public:
    using Base = JSPromiseReaction;

    DECLARE_EXPORT_INFO;
    DECLARE_VISIT_CHILDREN;

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

    static Structure* createStructure(VM&, JSGlobalObject*, JSValue);

    static JSFullPromiseReaction* create(VM&, JSValue promise, JSValue onFulfilled, JSValue onRejected, JSValue context, JSPromiseReaction* next);

    JSValue onFulfilled() const { return m_onFulfilled.get(); }
    JSValue onRejected() const { return m_onRejected.get(); }
    JSValue context() const { return m_context.get(); }

    void setOnFulfilled(VM& vm, JSValue value) { m_onFulfilled.set(vm, this, value); }
    void setOnRejected(VM& vm, JSValue value) { m_onRejected.set(vm, this, value); }
    void setContext(VM& vm, JSValue value) { m_context.set(vm, this, value); }

private:
    JSFullPromiseReaction(VM& vm, Structure* structure, JSValue promise, JSValue onFulfilled, JSValue onRejected, JSValue context, JSPromiseReaction* next)
        : Base(vm, structure, promise, next)
        , m_onFulfilled(onFulfilled, WriteBarrierEarlyInit)
        , m_onRejected(onRejected, WriteBarrierEarlyInit)
        , m_context(context, WriteBarrierEarlyInit)
    {
    }

    WriteBarrier<Unknown> m_onFulfilled;
    WriteBarrier<Unknown> m_onRejected;
    WriteBarrier<Unknown> m_context;
};

STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(JSSlimPromiseReaction);
STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(JSFullPromiseReaction);

} // namespace JSC