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#pragma once
#include <util/system/align.h>
#include <util/system/defaults.h>
#include <new>
namespace NPrivate {
class TAdditionalStorageInfo {
public:
constexpr TAdditionalStorageInfo(size_t length) noexcept
: Length_(length)
{
}
constexpr size_t Length() const noexcept {
return Length_;
}
private:
size_t Length_;
};
}
template <class T>
class alignas(::NPrivate::TAdditionalStorageInfo) TAdditionalStorage {
using TInfo = ::NPrivate::TAdditionalStorageInfo;
public:
inline TAdditionalStorage() noexcept = default;
inline ~TAdditionalStorage() = default;
inline void* operator new(size_t len1, size_t len2) {
static_assert(alignof(T) >= alignof(TInfo));
Y_ASSERT(len1 == sizeof(T));
void* data = ::operator new(CombinedSizeOfInstanceWithTInfo() + len2);
void* info = InfoPtr(static_cast<T*>(data));
Y_UNUSED(new (info) TInfo(len2));
return data;
}
inline void operator delete(void* ptr) noexcept {
DoDelete(ptr);
}
inline void operator delete(void* ptr, size_t) noexcept {
DoDelete(ptr);
}
inline void operator delete(void* ptr, size_t, size_t) noexcept {
/*
* this delete operator can be called automagically by compiler
*/
DoDelete(ptr);
}
inline void* AdditionalData() const noexcept {
return (char*)(static_cast<const T*>(this)) + CombinedSizeOfInstanceWithTInfo();
}
static inline T* ObjectFromData(void* data) noexcept {
return reinterpret_cast<T*>(static_cast<char*>(data) - CombinedSizeOfInstanceWithTInfo());
}
inline size_t AdditionalDataLength() const noexcept {
return InfoPtr(static_cast<const T*>(this))->Length();
}
private:
static inline void DoDelete(void* ptr) noexcept {
TInfo* info = InfoPtr(static_cast<T*>(ptr));
info->~TInfo();
::operator delete(ptr);
}
static constexpr size_t CombinedSizeOfInstanceWithTInfo() noexcept {
return AlignUp(sizeof(T), alignof(TInfo)) + sizeof(TInfo);
}
static constexpr TInfo* InfoPtr(T* instance) noexcept {
return const_cast<TInfo*>(InfoPtr(static_cast<const T*>(instance)));
}
static constexpr const TInfo* InfoPtr(const T* instance) noexcept {
return reinterpret_cast<const TInfo*>(reinterpret_cast<const char*>(instance) + CombinedSizeOfInstanceWithTInfo() - sizeof(TInfo));
}
private:
void* operator new(size_t) = delete;
};
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