Duckstation/dep/rapidyaml/include/c4/szconv.hpp

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2024-02-03 16:18:15 +00:00
#ifndef _C4_SZCONV_HPP_
#define _C4_SZCONV_HPP_
/** @file szconv.hpp utilities to deal safely with narrowing conversions */
#include "c4/config.hpp"
#include "c4/error.hpp"
#include <limits>
namespace c4 {
C4_SUPPRESS_WARNING_GCC_CLANG_WITH_PUSH("-Wold-style-cast")
/** @todo this would be so much easier with calls to numeric_limits::max()... */
template<class SizeOut, class SizeIn>
struct is_narrower_size : std::conditional
<
(std::is_signed<SizeOut>::value == std::is_signed<SizeIn>::value)
?
(sizeof(SizeOut) < sizeof(SizeIn))
:
(
(sizeof(SizeOut) < sizeof(SizeIn))
||
(
(sizeof(SizeOut) == sizeof(SizeIn))
&&
(std::is_signed<SizeOut>::value && std::is_unsigned<SizeIn>::value)
)
),
std::true_type,
std::false_type
>::type
{
static_assert(std::is_integral<SizeIn >::value, "must be integral type");
static_assert(std::is_integral<SizeOut>::value, "must be integral type");
};
/** when SizeOut is wider than SizeIn, assignment can occur without reservations */
template<class SizeOut, class SizeIn>
C4_ALWAYS_INLINE
typename std::enable_if< ! is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
szconv(SizeIn sz) noexcept
{
return static_cast<SizeOut>(sz);
}
/** when SizeOut is narrower than SizeIn, narrowing will occur, so we check
* for overflow. Note that this check is done only if C4_XASSERT is enabled.
* @see C4_XASSERT */
template<class SizeOut, class SizeIn>
C4_ALWAYS_INLINE
typename std::enable_if<is_narrower_size<SizeOut, SizeIn>::value, SizeOut>::type
szconv(SizeIn sz) C4_NOEXCEPT_X
{
C4_XASSERT(sz >= 0);
C4_XASSERT_MSG((SizeIn)sz <= (SizeIn)std::numeric_limits<SizeOut>::max(), "size conversion overflow: in=%zu", (size_t)sz);
SizeOut szo = static_cast<SizeOut>(sz);
return szo;
}
C4_SUPPRESS_WARNING_GCC_CLANG_POP
} // namespace c4
#endif /* _C4_SZCONV_HPP_ */