ArchiveReferenceMarker.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/Object.h"
#include "Serialization/ArchiveUObject.h"
 
enum class EArchiveReferenceMarkerFlags : uint32
{
    None = 0,
    SkipCompilingAssets = 1 // Skip serialization of assets still being compiled, some data might be missing.
};
 
ENUM_CLASS_FLAGS(EArchiveReferenceMarkerFlags);
 
class FArchiveReferenceMarker : public FArchiveUObject
{
public:
    FArchiveReferenceMarker( TArray<UObject*>& SourceObjects, EArchiveReferenceMarkerFlags InFlags = EArchiveReferenceMarkerFlags::None)
    {
        ArIsObjectReferenceCollector = true;
        ArIgnoreOuterRef = true;
        SetShouldSkipCompilingAssets((InFlags & EArchiveReferenceMarkerFlags::SkipCompilingAssets) != EArchiveReferenceMarkerFlags::None);
 
        for ( int32 ObjectIndex = 0; ObjectIndex < SourceObjects.Num(); ObjectIndex++ )
        {
            UObject* Object = SourceObjects[ObjectIndex];
            Object->Mark(OBJECTMARK_TagImp);
 
            // OBJECTMARK_TagImp is used to allow serialization of objects which we would otherwise ignore.
            Object->Serialize(*this);
        }
 
        for ( int32 ObjectIndex = 0; ObjectIndex < SourceObjects.Num(); ObjectIndex++ )
        {
            UObject* Object = SourceObjects[ObjectIndex];
            Object->UnMark(OBJECTMARK_TagImp);
        }
    }
 
    FArchive& operator<<( UObject*& Object )
    {
        if (Object != NULL && !(Object->HasAnyMarks(OBJECTMARK_TagExp) || !IsValidChecked(Object) || Object->IsUnreachable()) )
        {
            Object->Mark(OBJECTMARK_TagExp);
 
            const bool bIgnoreObject = 
                // No need to call Serialize from here for any objects that were part of our root set.
                // By preventing re-entrant serialization using the OBJECTMARK_TagImp flag (instead of just marking each object in the root set with
                // OBJECTMARK_TagExp prior to calling Serialize) we can determine which objects from our root set are being referenced
                // by other objects in our root set.
                Object->HasAnyMarks(OBJECTMARK_TagImp);
 
            if ( bIgnoreObject == false )
            {
                Object->Serialize( *this );
            }
        }
 
        return *this;
    }
};