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#pragma once
#include <concepts>
#include <memory>
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
template <size_t MaxByteSize>
class TErasedStorage;
////////////////////////////////////////////////////////////////////////////////
namespace NDetail {
template <class T>
struct TIsErasedStorage
: public std::false_type
{ };
template <size_t N>
struct TIsErasedStorage<TErasedStorage<N>>
: public std::true_type
{ };
} // namespace NDetail
////////////////////////////////////////////////////////////////////////////////
template <class T, size_t ErasedStorageMaxByteSize>
concept CTriviallyErasable =
std::default_initializable<T> &&
std::is_trivially_destructible_v<T> &&
std::is_trivially_copyable_v<T> &&
(sizeof(T) <= ErasedStorageMaxByteSize) &&
(alignof(T) <= ErasedStorageMaxByteSize) &&
!std::is_reference_v<T> &&
!NDetail::TIsErasedStorage<T>::value;
////////////////////////////////////////////////////////////////////////////////
// This class does not call dtor of erased object
// thus we require trivial destructability.
template <size_t MaxByteSize>
class TErasedStorage
{
public:
static constexpr size_t ByteSize = MaxByteSize;
template <CTriviallyErasable<MaxByteSize> TDecayedConcrete>
explicit TErasedStorage(TDecayedConcrete concrete) noexcept;
TErasedStorage(const TErasedStorage& other) = default;
TErasedStorage& operator=(const TErasedStorage& other) = default;
template <CTriviallyErasable<MaxByteSize> TDecayedConcrete>
TDecayedConcrete& AsConcrete() & noexcept;
template <CTriviallyErasable<MaxByteSize> TDecayedConcrete>
const TDecayedConcrete& AsConcrete() const & noexcept;
template <CTriviallyErasable<MaxByteSize> TDecayedConcrete>
TDecayedConcrete&& AsConcrete() && noexcept;
bool operator==(const TErasedStorage& other) const = default;
private:
// NB(arkady-e1ppa): aligned_storage is deprecated.
alignas(MaxByteSize) std::byte Bytes_[MaxByteSize];
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define ERASED_STORAGE_INL_H_
#include "erased_storage-inl.h"
#undef ERASED_STORAGE_INL_H_
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