StructuredArchiveSlotBase.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
 
class FArchive;
class FStructuredArchive;
struct FArchiveState;
 
namespace UE::StructuredArchive::Private
{
    struct FElementId
    {
        FElementId() = default;
 
        explicit FElementId(uint32 InId)
            : Id(InId)
        {
        }
 
        bool IsValid() const
        {
            return Id != 0;
        }
 
        void Reset()
        {
            Id = 0;
        }
 
        bool operator==(const FElementId& Rhs) const
        {
            return Id == Rhs.Id;
        }
 
        bool operator!=(const FElementId& Rhs) const
        {
            return Id != Rhs.Id;
        }
 
    private:
        uint32 Id = 0;
    };
 
    // Represents a position of a slot within the hierarchy.
    class FSlotPosition
    {
        friend FStructuredArchive;
 
    public:
        int32 Depth;
        FElementId ElementId;
 
        inline explicit FSlotPosition(int32 InDepth, FElementId InElementId)
            : Depth(InDepth)
            , ElementId(InElementId)
        {
        }
    };
 
    // The base class of all slot types
    class FSlotBase
#if WITH_TEXT_ARCHIVE_SUPPORT
        : protected FSlotPosition
#endif
    {
        friend FStructuredArchive;
 
    protected:
        // Token which needs to be passed to the constructor, so only friends are able to do so, but
        // still allows emplacement without the container being a friend.
        enum class EPrivateToken {};
 
    public:
#if WITH_TEXT_ARCHIVE_SUPPORT
        inline explicit FSlotBase(EPrivateToken, FStructuredArchive& InStructuredArchive, int32 InDepth, FElementId InElementId)
            : FSlotPosition(InDepth, InElementId)
            , StructuredArchive(InStructuredArchive)
        {
        }
#else
        UE_FORCEINLINE_HINT explicit FSlotBase(EPrivateToken, FStructuredArchive& InStructuredArchive)
            : StructuredArchive(InStructuredArchive)
        {
        }
#endif
 
        CORE_API FArchive& GetUnderlyingArchive() const;
        CORE_API const FArchiveState& GetArchiveState() const;
 
    protected:
        FStructuredArchive& StructuredArchive;
    };
}