FindObjectReferencers.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/Package.h"
#include "UObject/UObjectIterator.h"
#include "Serialization/FindReferencersArchive.h"
 
template< class T >
class TFindObjectReferencers : public TMultiMap<T*, UObject*>
{
public:
 
    TFindObjectReferencers( TArray< T* > TargetObjects, UPackage* PackageToCheck=NULL, bool bIgnoreTemplates = true, bool bFindAlsoWeakReferences = false)
    : TMultiMap< T*, UObject* >()
    {
        TArray<UObject*> ReferencedObjects;
        TMap<UObject*, int32> ReferenceCounts;
 
        FFindReferencersArchive FindReferencerAr(nullptr, (TArray<UObject*>&)TargetObjects, bFindAlsoWeakReferences);
 
        // Loop over every object to find any reference that may exist for the target objects
        for (FThreadSafeObjectIterator It; It; ++It)
        {
            UObject* PotentialReferencer = *It;
            if ( !TargetObjects.Contains(PotentialReferencer)
            &&  (PackageToCheck == NULL || PotentialReferencer->IsIn(PackageToCheck))
            &&  (!bIgnoreTemplates || !PotentialReferencer->IsTemplate()) )
            {
                FindReferencerAr.ResetPotentialReferencer(PotentialReferencer);
 
                ReferenceCounts.Reset();
                if ( FindReferencerAr.GetReferenceCounts(ReferenceCounts) > 0 )
                {
                    // here we don't really care about the number of references from PotentialReferencer to the target object...just that it's a referencer
                    ReferencedObjects.Reset();
                    ReferenceCounts.GenerateKeyArray(ReferencedObjects);
                    for ( int32 RefIndex = 0; RefIndex < ReferencedObjects.Num(); RefIndex++ )
                    {
                        this->Add(static_cast<T*>(ReferencedObjects[RefIndex]), PotentialReferencer);
                    }
                }
            }
        }
    }
 
private:
//  TMap< T*, TMultiMap<UObject*, FProperty*> >     ReferenceProperties;
};