ClickHouse/libs/libcommon/include/ext/bit_cast.hpp

43 lines
1.2 KiB
C++
Raw Normal View History

2015-11-06 14:49:24 +00:00
#pragma once
#include <type_traits>
namespace ext
{
template <typename To, typename From>
union bit_cast_helper_t
{
using dst = std::decay_t<To>;
using src = std::decay_t<From>;
static_assert(std::is_copy_constructible<dst>::value, "destination type must be CopyConstructible");
static_assert(std::is_copy_constructible<src>::value, "source type must be CopyConstructible");
/** value-initialize member `to` first in case destination type is larger than source */
dst to{};
src from;
bit_cast_helper_t(const From & from) : from{from} {}
operator dst() const { return to; }
};
/** \brief Returns value `from` converted to type `To` while retaining bit representation.
* `To` and `From` must satisfy `CopyConstructible`. */
template <typename To, typename From>
std::decay_t<To> bit_cast(const From & from)
{
return bit_cast_helper_t<To, From>{from};
};
/** \brief Returns value `from` converted to type `To` while retaining bit representation.
* `To` and `From` must satisfy `CopyConstructible`. */
template <typename To, typename From>
std::decay_t<To> safe_bit_cast(const From & from)
{
static_assert(sizeof(To) == sizeof(From), "bit cast on types of different width");
return bit_cast_helper_t<To, From>{from};
};
}