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#pragma once


/** An RAII wrapper for std::atomic<T*>. */
template <typename T> class cAtomicUniquePtr
{
  public:
	static_assert(!std::is_array<T>::value, "cAtomicUniquePtr does not support arrays");
	DISALLOW_COPY_AND_ASSIGN(cAtomicUniquePtr);

	cAtomicUniquePtr() noexcept :
		m_Ptr(nullptr)
	{
	}


	cAtomicUniquePtr(std::unique_ptr<T> a_Ptr) noexcept :
		m_Ptr(a_Ptr.release())
	{
	}

	cAtomicUniquePtr & operator=(std::unique_ptr<T> a_Ptr) noexcept
	{
		store(std::move(a_Ptr));
		return *this;
	}

	~cAtomicUniquePtr() noexcept { delete load(); }

	operator T *() const noexcept { return load(); }

	bool compare_exchange_weak(
		T *& a_Expected,
		std::unique_ptr<T> && a_Desired,
		std::memory_order a_Order = std::memory_order_seq_cst
	) noexcept
	{
		bool DidExchange = m_Ptr.compare_exchange_weak(a_Expected, a_Desired.get(), a_Order);
		if (DidExchange)
		{
			// Only release ownership from the caller if the exchange occurred
			a_Desired.release();
		}
		return DidExchange;
	}

	bool compare_exchange_strong(
		T *& a_Expected,
		std::unique_ptr<T> && a_Desired,
		std::memory_order a_Order = std::memory_order_seq_cst
	) noexcept
	{
		bool DidExchange = m_Ptr.compare_exchange_strong(a_Expected, a_Desired.get(), a_Order);
		if (DidExchange)
		{
			// Only release ownership from the caller if the exchange occurred
			a_Desired.release();
		}
		return DidExchange;
	}

	std::unique_ptr<T> exchange(
		std::unique_ptr<T> a_Ptr,
		std::memory_order a_Order = std::memory_order_seq_cst
	) noexcept
	{
		return std::unique_ptr<T> {m_Ptr.exchange(a_Ptr.release(), a_Order)};
	}

	T * load(std::memory_order a_Order = std::memory_order_seq_cst) const noexcept { return m_Ptr.load(a_Order); }

	void store(std::unique_ptr<T> a_Ptr, std::memory_order a_Order = std::memory_order_seq_cst) noexcept
	{
		// Store new value and delete old value
		delete m_Ptr.exchange(a_Ptr.release(), a_Order);
	}

  private:
	std::atomic<T *> m_Ptr;
};