Field.h

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#pragma once
 
#include "UObjectGlobals.h"
 
namespace Karma
{
    class UObject;
    class UClass;
    class FField;
    class FFieldClass;

    class KARMA_API FFieldVariant
    {
        union FFieldObjectUnion
        {
            FField* Field;
            UObject* Object;
        } Container;
 
        bool bIsUObject;
 
    public:

        FFieldVariant()
            : bIsUObject(false)
        {
            Container.Field = nullptr;
        }

        FFieldVariant(const FField* InField)
            : bIsUObject(false)
        {
            Container.Field = const_cast<FField*>(InField);
        }

        template <
            typename T,
            decltype(ImplicitConv<const UObject*>(std::declval<T>()))* = nullptr
        >
        FFieldVariant(T&& InObject)
            : bIsUObject(true)
        {
            Container.Object = const_cast<UObject*>(ImplicitConv<const UObject*>(InObject));
        }

        inline bool IsUObject() const
        {
            return bIsUObject;
        }

        inline bool IsValid() const
        {
            return !!Container.Object;
        }

        bool IsValidLowLevel() const;

        inline operator bool() const
        {
            return IsValid();
        }

        bool IsA(const UClass* InClass) const;

        bool IsA(const FFieldClass* InClass) const;
 
        template <typename T>
        bool IsA() const
        {
            static_assert(sizeof(T) > 0, "T must not be an incomplete type");
            return IsA(T::StaticClass());
        }
 
        /*
        template <typename T>
        typename TEnableIf<TIsDerivedFrom<T, UObject>::IsDerived, T*>::Type Get() const
        {
            static_assert(sizeof(T) > 0, "T must not be an incomplete type");
            if (IsA(T::StaticClass()))
            {
                return static_cast<T*>(Container.Object);
            }
            return nullptr;
        }
 
        template <typename T>
        typename TEnableIf<!TIsDerivedFrom<T, UObject>::IsDerived, T*>::Type Get() const
        {
            static_assert(sizeof(T) > 0, "T must not be an incomplete type");
            if (IsA(T::StaticClass()))
            {
                return static_cast<T*>(Container.Field);
            }
            return nullptr;
        }
        */

        UObject* ToUObject() const
        {
            if (bIsUObject)
            {
                return Container.Object;
            }
            else
            {
                return nullptr;
            }
        }

        FField* ToField() const
        {
            if (!bIsUObject)
            {
                return Container.Field;
            }
            else
            {
                return nullptr;
            }
        }

        FORCEINLINE FField* ToFieldUnsafe() const
        {
            return Container.Field;
        }

        FORCEINLINE UObject* ToUObjectUnsafe() const
        {
            return Container.Object;
        }

        void* GetRawPointer() const
        {
            return Container.Field;
        }
 
        FFieldVariant GetOwnerVariant() const;
        UClass* GetOwnerClass() const;
        const std::string& GetFullName() const;
        const std::string& GetPathName() const;
        const std::string& GetName() const;
        const std::string& GetClassName() const;
        const std::string& GetFName() const;
        bool IsNative() const;
        //UPackage* GetOutermost() const;
 
        bool operator==(const FFieldVariant& Other) const
        {
            return Container.Field == Other.Container.Field;
        }
        
        bool operator!=(const FFieldVariant& Other) const
        {
            return Container.Field != Other.Container.Field;
        }
/*
#if WITH_EDITORONLY_DATA
        bool HasMetaData(const FName& Key) const;
#endif*/

        /*friend uint32_t GetTypeHash(const FFieldVariant& InFieldVariant)
        {
            return GetTypeHash(InFieldVariant.GetRawPointer());
        }
 
        KARMA_API friend FArchive& operator << (FArchive& Ar, FFieldVariant& InOutField);*/
    };

    class KARMA_API FFieldClass
    {
        std::string m_Name;

        uint64_t m_Id;
        
        uint64_t m_CastFlags;
        
        EClassFlags ClassFlags;
        
        FFieldClass* SuperClass;
        
        FField* DefaultObject;
        
        FField* (*ConstructFn)(const FFieldVariant&, const std::string&, EObjectFlags);
        
        //FThreadSafeCounter UnqiueNameIndexCounter;

        FField* ConstructDefaultObject();
 
    public:
        KR_NONCOPYABLE(FFieldClass);

        static KarmaVector<FFieldClass*>& GetAllFieldClasses();

        static std::unordered_map<std::string, FFieldClass*>& GetNameToFieldClassMap();

        explicit FFieldClass(const char* InCPPName, uint64_t InId, uint64_t InCastFlags, FFieldClass* InSuperClass, FField* (*ConstructFnPtr)(const FFieldVariant&, const std::string&, EObjectFlags));

        ~FFieldClass();

        inline const std::string& GetName() const
        {
            return m_Name;
        }
        
        inline uint64_t GetId() const
        {
            return m_Id;
        }

        inline uint64_t GetCastFlags() const
        {
            return m_CastFlags;
        }
        inline bool HasAnyCastFlags(const uint64_t InCastFlags) const
        {
            return !!(m_CastFlags & InCastFlags);
        }
        inline bool HasAllCastFlags(const uint64_t InCastFlags) const
        {
            return (m_CastFlags & InCastFlags) == InCastFlags;
        }

        inline bool IsChildOf(const FFieldClass* InClass) const
        {
            const uint64_t OtherClassId = InClass->GetId();
            return OtherClassId ? !!(m_CastFlags & OtherClassId) : IsChildOf_Walk(InClass);
        }
 
        const std::string& GetDescription() const;
        const std::string& GetDisplayNameText() const;
 
        FField* Construct(const FFieldVariant& InOwner, const std::string& InName, EObjectFlags InFlags = RF_NoFlags) const
        {
            return ConstructFn(InOwner, InName, InFlags);
        }
 
        FFieldClass* GetSuperClass() const
        {
            return SuperClass;
        }

        FField* GetDefaultObject()
        {
            if (!DefaultObject)
            {
                DefaultObject = ConstructDefaultObject();
                KR_CORE_ASSERT(DefaultObject, "Default object is null");
            }
            return DefaultObject;
        }
 
        /*
        bool HasAnyClassFlags(EClassFlags FlagsToCheck) const
        {
            return EnumHasAnyFlags(ClassFlags, FlagsToCheck) != 0;
        }
 
        int32_t GetNextUniqueNameIndex()
        {
            return UnqiueNameIndexCounter.Increment();
        }
 
        friend FArchive& operator << (FArchive& Ar, FFieldClass& InField)
        {
            check(false);
            return Ar;
        }
        KARMA_API friend FArchive& operator << (FArchive& Ar, FFieldClass*& InOutFieldClass);*/
 
    private:
        bool IsChildOf_Walk(const FFieldClass* InBaseClass) const
        {
            for (const FFieldClass* TempField = this; TempField; TempField = TempField->GetSuperClass())
            {
                if (TempField == InBaseClass)
                {
                    return true;
                }
            }
            return false;
        }
    };

    class KARMA_API FField
    {
        FFieldClass* ClassPrivate;
 
    public:
        KR_NONCOPYABLE(FField)
 
        typedef FField Super;
        typedef FField ThisClass;
        typedef FField BaseFieldClass;
        typedef FFieldClass FieldTypeClass;

        FFieldVariant m_Owner;

        FField* m_Next;

        std::string m_NamePrivate;

        EObjectFlags m_FlagsPrivate;
 
    public:
        void Rename(const std::string& NewName);
 
        //static FFieldClass* StaticClass();
    };
}