EM_Task/CoreUObject/Private/UObject/PropertyClass.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "CoreMinimal.h"
#include "UObject/ObjectMacros.h"
#include "Templates/Casts.h"
#include "UObject/UnrealType.h"
#include "UObject/UnrealTypePrivate.h"
#include "UObject/LinkerPlaceholderClass.h"
#include "Misc/ConfigCacheIni.h"
#include "UObject/PropertyHelper.h"

// WARNING: This should always be the last include in any file that needs it (except .generated.h)
#include "UObject/UndefineUPropertyMacros.h"

/*-----------------------------------------------------------------------------
        FClassProperty.
-----------------------------------------------------------------------------*/
IMPLEMENT_FIELD(FClassProperty)

#if WITH_EDITORONLY_DATA
FClassProperty::FClassProperty(UField* InField)
    : FObjectProperty(InField)
{
    UClassProperty* SourceProperty = CastChecked<UClassProperty>(InField);
    MetaClass                      = SourceProperty->MetaClass;
}
#endif  // WITH_EDITORONLY_DATA

void FClassProperty::BeginDestroy()
{
#if USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING
    if (ULinkerPlaceholderClass* PlaceholderClass = Cast<ULinkerPlaceholderClass>(MetaClass))
    {
        PlaceholderClass->RemoveReferencingProperty(this);
    }
#endif  // USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING

    Super::BeginDestroy();
}

void FClassProperty::PostDuplicate(const FField& InField)
{
    const FClassProperty& Source = static_cast<const FClassProperty&>(InField);
    MetaClass                    = Source.MetaClass;
    Super::PostDuplicate(InField);
}

void FClassProperty::Serialize(FArchive& Ar)
{
    Super::Serialize(Ar);
    Ar << MetaClass;

#if USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING
    if (Ar.IsLoading() || Ar.IsObjectReferenceCollector())
    {
        if (ULinkerPlaceholderClass* PlaceholderClass = Cast<ULinkerPlaceholderClass>(MetaClass))
        {
            PlaceholderClass->AddReferencingProperty(this);
        }
    }
#endif  // USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING

    if (!MetaClass)
    {
        // If we failed to load the MetaClass and we're not a CDO, that means we relied on a class that has been removed or doesn't exist.
        // The most likely cause for this is either an incomplete recompile, or if content was migrated between games that had native class dependencies
        // that do not exist in this game.  We allow blueprint classes to continue, because compile on load will error out, and stub the class that was using it
        UClass* TestClass = dynamic_cast<UClass*>(GetOwnerStruct());
        if (TestClass && TestClass->HasAllClassFlags(CLASS_Native) && !TestClass->HasAllClassFlags(CLASS_NewerVersionExists) && (TestClass->GetOutermost() != GetTransientPackage()))
        {
            checkf(false, TEXT("Class property tried to serialize a missing class.  Did you remove a native class and not fully recompile?"));
        }
    }
}

#if USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING
void FClassProperty::SetMetaClass(UClass* NewMetaClass)
{
    if (ULinkerPlaceholderClass* NewPlaceholderClass = Cast<ULinkerPlaceholderClass>(NewMetaClass))
    {
        NewPlaceholderClass->AddReferencingProperty(this);
    }

    if (ULinkerPlaceholderClass* OldPlaceholderClass = Cast<ULinkerPlaceholderClass>(MetaClass))
    {
        OldPlaceholderClass->RemoveReferencingProperty(this);
    }
    MetaClass = NewMetaClass;
}
#endif  // USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING

void FClassProperty::AddReferencedObjects(FReferenceCollector& Collector)
{
    Collector.AddReferencedObject(MetaClass);
    Super::AddReferencedObjects(Collector);
}

const TCHAR* FClassProperty::ImportText_Internal(const TCHAR* Buffer, void* Data, int32 PortFlags, UObject* Parent, FOutputDevice* ErrorText) const
{
    const TCHAR* Result = FObjectProperty::ImportText_Internal(Buffer, Data, PortFlags, Parent, ErrorText);
    if (Result)
    {
        if (UClass* AssignedPropertyClass = dynamic_cast<UClass*>(GetObjectPropertyValue(Data)))
        {
#if USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING
            FLinkerLoad* ObjectLinker = (Parent != nullptr) ? Parent->GetClass()->GetLinker() : GetLinker();
            auto IsDeferringValueLoad = [](const UClass* Class) -> bool
            {
                const ULinkerPlaceholderClass* Placeholder = Cast<ULinkerPlaceholderClass>(Class);
                return Placeholder && !Placeholder->IsMarkedResolved();
            };
            const bool bIsDeferringValueLoad = IsDeferringValueLoad(MetaClass) || ((!ObjectLinker || (ObjectLinker->LoadFlags & LOAD_DeferDependencyLoads) != 0) && IsDeferringValueLoad(AssignedPropertyClass));

#if USE_DEFERRED_DEPENDENCY_CHECK_VERIFICATION_TESTS
            check(bIsDeferringValueLoad || !(Cast<ULinkerPlaceholderClass>(MetaClass) || Cast<ULinkerPlaceholderClass>(AssignedPropertyClass)));
#endif  // USE_DEFERRED_DEPENDENCY_CHECK_VERIFICATION_TESTS

#else   // USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING
            bool const bIsDeferringValueLoad = false;
#endif  // USE_CIRCULAR_DEPENDENCY_LOAD_DEFERRING

            // Validate metaclass.
            if ((!AssignedPropertyClass->IsChildOf(MetaClass)) && !bIsDeferringValueLoad)
            {
                // the object we imported doesn't implement our interface class
                ErrorText->Logf(TEXT("Invalid object '%s' specified for property '%s'"), *AssignedPropertyClass->GetFullName(), *GetName());
                SetObjectPropertyValue(Data, NULL);
                Result = NULL;
            }
        }
    }
    return Result;
}

FString FClassProperty::GetCPPType(FString* ExtendedTypeText, uint32 CPPExportFlags) const
{
    check(MetaClass);
    return GetCPPTypeCustom(ExtendedTypeText, CPPExportFlags,
                            FString::Printf(TEXT("%s%s"), MetaClass->GetPrefixCPP(), *MetaClass->GetName()));
}

FString FClassProperty::GetCPPTypeCustom(FString* ExtendedTypeText, uint32 CPPExportFlags, const FString& InnerNativeTypeName) const
{
    if (PropertyFlags & CPF_UObjectWrapper)
    {
        ensure(!InnerNativeTypeName.IsEmpty());
        return FString::Printf(TEXT("TSubclassOf<%s> "), *InnerNativeTypeName);
    }
    else
    {
        return TEXT("UClass*");
    }
}

FString FClassProperty::GetCPPTypeForwardDeclaration() const
{
    return FString::Printf(TEXT("class %s%s;"), MetaClass->GetPrefixCPP(), *MetaClass->GetName());
}

FString FClassProperty::GetCPPMacroType(FString& ExtendedTypeText) const
{
    ExtendedTypeText = TEXT("UClass");
    return TEXT("OBJECT");
}

bool FClassProperty::SameType(const FProperty* Other) const
{
    return Super::SameType(Other) && (MetaClass == ((FClassProperty*)Other)->MetaClass);
}

bool FClassProperty::Identical(const void* A, const void* B, uint32 PortFlags) const
{
    UObject* ObjectA = A ? GetObjectPropertyValue(A) : nullptr;
    UObject* ObjectB = B ? GetObjectPropertyValue(B) : nullptr;

    check(ObjectA == nullptr || ObjectA->IsA<UClass>());
    check(ObjectB == nullptr || ObjectB->IsA<UClass>());
    return (ObjectA == ObjectB);
}

#include "UObject/DefineUPropertyMacros.h"