Refactor narrow - simplify & move is_same_signedness into function, remove uneeded detail namespace. Merge 2 if's with a ||.

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Robert Andrzejuk 2020-04-29 20:11:44 +02:00 committed by GitHub
parent 1999b48a51
commit 1e5f44d3ea
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@ -100,15 +100,6 @@ struct narrowing_error : public std::exception
{
};
namespace details
{
template <class T, class U>
struct is_same_signedness
: public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value>
{
};
} // namespace details
// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
template <class T, class U>
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
@ -118,10 +109,17 @@ constexpr
#endif
T narrow(U u) noexcept(false)
{
T t = narrow_cast<T>(u);
if (static_cast<U>(t) != u) throw narrowing_error{};
if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
constexpr const bool is_same_signedness = std::is_signed<T>::value == std::is_signed<U>::value;
const T t = narrow_cast<T>(u);
if (static_cast<U>(t) != u
|| (!is_same_signedness
&& ((t < T{}) != (u < U{}))))
{
throw narrowing_error{};
}
return t;
}