UE 共享指针 共享引用

class FTestA {
public:
	FTestA() {
		UE_LOG(LogTemp, Warning, TEXT("FTestA 构造"));
	}
	void TestFun() {
		UE_LOG(LogTemp, Warning, TEXT("FTestA TestFun方法"));
	}
	~FTestA() {
		UE_LOG(LogTemp, Warning, TEXT("FTestA 析构"));
	}
};

class FTestAChild : public FTestA {
public:
	FTestAChild() {
		UE_LOG(LogTemp, Warning, TEXT("FTestAChild 构造"));
	}
	void TestFunChild() {
		UE_LOG(LogTemp, Warning, TEXT("FTestAChild TestFunChild方法"));
	}
	~FTestAChild() {
		UE_LOG(LogTemp, Warning, TEXT("FTestAChild 析构"));
	}
};

UFUNCTION(BlueprintCallable)
void MyTest();

void AMyIntelligentPointer::MyTest()
{
	//共享指针
	{
		TSharedPtr<FTestA, ESPMode::NotThreadSafe> SharedPtr = MakeShareable(new FTestA);	//创建时SharedReferenceCount=1
		if (SharedPtr.IsValid()) {
			SharedPtr->TestFun();

			int32 SharedReferenceCount = SharedPtr.GetSharedReferenceCount();
			UE_LOG(LogTemp, Warning, TEXT("SharedReferenceCount : %d"), SharedReferenceCount);

			//手动释放
			//SharedPtr = nullptr;
			UE_LOG(LogTemp, Warning, TEXT("SharedPtr.IsUnique : %d"), SharedPtr.IsUnique());
			SharedPtr.Reset();
		}
	}

	//共享引用
	{
		//TSharedRef<FTestA, ESPMode::NotThreadSafe> SharedRef = MakeShareable(new FTestA()); //将共享指针隐式转换成引用
		TSharedRef<FTestA, ESPMode::NotThreadSafe> SharedRef(new FTestA);
		SharedRef->TestFun();
		int32 SharedReferenceCount = SharedRef.GetSharedReferenceCount();
		UE_LOG(LogTemp, Warning, TEXT("SharedReferenceCount : %d"), SharedReferenceCount);
		UE_LOG(LogTemp, Warning, TEXT("SharedRef.IsUnique : %d"), SharedRef.IsUnique());
	}

	//相互转化
	{
		//共享引用转化成共享指针
		UE_LOG(LogTemp, Warning, TEXT("共享引用转化成共享指针"));
		TSharedRef<FTestA, ESPMode::NotThreadSafe> SharedRef(new FTestA);
		TSharedPtr<FTestA, ESPMode::NotThreadSafe> SharedPtr = SharedRef;
	}
	{
		//共享指针转化成共享引用
		UE_LOG(LogTemp, Warning, TEXT("共享指针转化成共享引用"));
		TSharedPtr<FTestA, ESPMode::NotThreadSafe> SharedPtr = MakeShareable(new FTestA);
		TSharedRef<FTestA, ESPMode::NotThreadSafe> SharedRef = SharedPtr.ToSharedRef();
	}

	//继承关系转化
	{
		TSharedPtr<FTestA, ESPMode::NotThreadSafe> SharedPtr = MakeShareable(new FTestAChild);
		if(SharedPtr.IsValid()) {
			SharedPtr->TestFun();
			TSharedPtr<FTestAChild, ESPMode::NotThreadSafe> SharedPtr2 = StaticCastSharedPtr<FTestAChild>(SharedPtr);	//ConstCastSharedPtr：常量共享指针转化
			if (SharedPtr2.IsValid()) {
				SharedPtr2->TestFunChild();
			}
		}
	}
}