VVMAccessor.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#if WITH_VERSE_VM || defined(__INTELLISENSE__)
 
#include "CoreTypes.h"
#include "HAL/Platform.h"
#include "VVMContext.h"
#include "VVMGlobalTrivialEmergentTypePtr.h"
#include "VerseVM/VVMEnumerator.h"
#include "VerseVM/VVMFunction.h"
#include "VerseVM/VVMUniqueString.h"
#include "VerseVM/VVMValue.h"
 
namespace Verse
{
 
struct VAccessor : VCell
{
    DECLARE_DERIVED_VCPPCLASSINFO(COREUOBJECT_API, VCell);
    COREUOBJECT_API static TGlobalTrivialEmergentTypePtr<&StaticCppClassInfo> GlobalTrivialEmergentType;
 
    static VAccessor& NewUninitialized(FAllocationContext Context, uint32 InNumAccessors)
    {
        FLayout Layout = CalcLayout(InNumAccessors);
        return *new (Context.AllocateFastCell(Layout.TotalSize)) VAccessor(Context, InNumAccessors);
    }
 
    static void SerializeLayout(FAllocationContext Context, VAccessor*& This, FStructuredArchiveVisitor& Visitor);
    COREUOBJECT_API void SerializeImpl(FAllocationContext Context, FStructuredArchiveVisitor& Visitor);
 
    // `NumParams` -1 and -2 for getters and setters respectively to align them to trailing array positions
    TWriteBarrier<VUniqueString>* FindGetter(uint32 NumParams)
    {
        return (GetGettersBegin() + (NumParams - 1));
    }
    TWriteBarrier<VUniqueString>* FindSetter(uint32 NumParams)
    {
        return (GetSettersBegin() + (NumParams - 2));
    }
    void AddGetter(FAllocationContext Context, uint32 NumParams, VUniqueString& Name)
    {
        FindGetter(NumParams)->Set(Context, Name);
    }
    void AddSetter(FAllocationContext Context, uint32 NumParams, VUniqueString& Name)
    {
        FindSetter(NumParams)->Set(Context, Name);
    }
 
private:
    friend struct VAccessChain;
    TWriteBarrier<VUniqueString>* GetGettersBegin() { return BitCast<TWriteBarrier<VUniqueString>*>(BitCast<std::byte*>(this) + GetLayout().GettersOffset); }
    TWriteBarrier<VUniqueString>* GetGettersEnd() { return GetGettersBegin() + NumAccessors; }
 
    TWriteBarrier<VUniqueString>* GetSettersBegin() { return BitCast<TWriteBarrier<VUniqueString>*>(BitCast<std::byte*>(this) + GetLayout().SettersOffset); }
    TWriteBarrier<VUniqueString>* GetSettersEnd() { return GetSettersBegin() + NumAccessors; }
 
    uint32 NumAccessors;
    TWriteBarrier<VCell> Trailing[];
 
    struct FLayout
    {
        int32 GettersOffset;
        int32 SettersOffset;
        int32 TotalSize;
    };
 
    static FLayout CalcLayout(uint32 NumAccessors)
    {
        FStructBuilder StructBuilder;
        StructBuilder.AddMember(offsetof(VAccessor, Trailing), alignof(VAccessor));
 
        FLayout Layout;
        Layout.GettersOffset = StructBuilder.AddMember(sizeof(TWriteBarrier<VUniqueString>) * NumAccessors, alignof(TWriteBarrier<VUniqueString>));
        Layout.SettersOffset = StructBuilder.AddMember(sizeof(TWriteBarrier<VUniqueString>) * NumAccessors, alignof(TWriteBarrier<VUniqueString>));
        Layout.TotalSize = StructBuilder.GetSize();
        return Layout;
    }
 
    FLayout GetLayout() const
    {
        return CalcLayout(NumAccessors);
    }
 
    VAccessor(FAllocationContext Context, uint32 InNumAccessors)
        : VCell(Context, &GlobalTrivialEmergentType.Get(Context))
        , NumAccessors(InNumAccessors)
    {
        for (TWriteBarrier<VUniqueString>* Getter = GetGettersBegin(); Getter != GetGettersEnd(); ++Getter)
        {
            new (Getter) TWriteBarrier<VUniqueString>{};
        }
        for (TWriteBarrier<VUniqueString>* Setter = GetSettersBegin(); Setter != GetGettersEnd(); ++Setter)
        {
            new (Setter) TWriteBarrier<VUniqueString>{};
        }
    }
};
 
struct VAccessChain : VHeapValue
{
    DECLARE_DERIVED_VCPPCLASSINFO(COREUOBJECT_API, VHeapValue);
    COREUOBJECT_API static TGlobalTrivialEmergentTypePtr<&StaticCppClassInfo> GlobalTrivialEmergentType;
 
    COREUOBJECT_API static TGlobalHeapPtr<VEnumerator> AccessorEnum;
 
    uint32 ChainNum;
    TWriteBarrier<VAccessor> Accessor;
    TWriteBarrier<VValue> Self;
 
    static VAccessChain& New(FAllocationContext Context, VAccessor* InAccessor, VValue InSelf)
    {
        FLayout Layout = CalcLayout(InAccessor->NumAccessors);
        return *new (Context.AllocateFastCell(Layout.TotalSize)) VAccessChain(Context, InAccessor, InSelf);
    }
 
    static VAccessChain& New(FAllocationContext Context, VAccessChain& Other, VValue Value)
    {
        FLayout Layout = CalcLayout(Other.Accessor->NumAccessors);
        return *new (Context.AllocateFastCell(Layout.TotalSize)) VAccessChain(Context, Other, Value);
    }
 
    TArrayView<TWriteBarrier<VValue>> GetChain()
    {
        return TArrayView<TWriteBarrier<VValue>>(GetChainBegin(), ChainNum);
    }
 
private:
    TWriteBarrier<VCell> Trailing[];
 
    void Add(FAllocationContext Context, VValue Value)
    {
        checkSlow(ChainNum + 1 <= MaxArgs());
        (GetChainBegin() + ChainNum)->Set(Context, Value);
        ++ChainNum;
    }
 
    TWriteBarrier<VValue>* GetChainBegin() { return BitCast<TWriteBarrier<VValue>*>(BitCast<std::byte*>(this) + GetLayout().ChainOffset); }
    TWriteBarrier<VValue>* GetChainEnd() { return GetChainBegin() + MaxArgs(); }
 
    struct FLayout
    {
        int32 ChainOffset;
        int32 TotalSize;
    };
 
    uint32 MaxArgs()
    {
        return Accessor->NumAccessors + 1;
    }
 
    static FLayout CalcLayout(uint32 NumAccessors)
    {
        FStructBuilder StructBuilder;
        StructBuilder.AddMember(offsetof(VAccessChain, Trailing), alignof(VAccessChain));
 
        FLayout Layout;
        Layout.ChainOffset = StructBuilder.AddMember(sizeof(TWriteBarrier<VValue>) * NumAccessors + 1, alignof(TWriteBarrier<VValue>));
        Layout.TotalSize = StructBuilder.GetSize();
        return Layout;
    }
 
    FLayout GetLayout() const
    {
        return CalcLayout(Accessor->NumAccessors);
    }
 
    VAccessChain(FAllocationContext Context, VAccessor* InAccessor, VValue InSelf)
        : VHeapValue(Context, &GlobalTrivialEmergentType.Get(Context))
        , ChainNum(0)
        , Accessor(Context, InAccessor)
        , Self(Context, InSelf)
    {
        checkSlow(Accessor.Get() != nullptr);
        for (TWriteBarrier<VValue>* Arg = GetChainBegin(); Arg != GetChainEnd(); ++Arg)
        {
            new (Arg) TWriteBarrier<VValue>{};
        }
        Add(Context, *AccessorEnum.Get());
    }
 
    VAccessChain(FAllocationContext Context, VAccessChain& Other, VValue Value)
        : VAccessChain(Context, Other.Accessor.Get(), Other.Self.Get())
    {
        ChainNum = Other.ChainNum;
        for (uint32 Index = 0; Index < ChainNum; ++Index)
        {
            (GetChainBegin() + Index)->Set(Context, (Other.GetChainBegin() + Index)->Get());
        }
        Add(Context, Value);
    }
};
 
} // namespace Verse
#endif // WITH_VERSE_VM