feat: narrow for non totally ordered types (#986)

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Johel Ernesto Guerrero Peña 2021-06-23 18:28:45 -04:00 committed by GitHub
parent b26f6d5ec7
commit 8a4b9ed0bf
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2 changed files with 23 additions and 1 deletions

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@ -26,7 +26,7 @@ struct narrowing_error : public std::exception
};
// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
template <class T, class U>
template <class T, class U, typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
// clang-format off
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
@ -45,5 +45,22 @@ GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recogn
return t;
}
template <class T, class U, typename std::enable_if<!std::is_arithmetic<T>::value>::type* = nullptr>
// clang-format off
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
// clang-format on
constexpr T narrow(U u) noexcept(false)
{
const T t = narrow_cast<T>(u);
if (static_cast<U>(t) != u)
{
throw narrowing_error{};
}
return t;
}
} // namespace gsl
#endif // GSL_NARROW_H

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@ -17,6 +17,7 @@
#include <gtest/gtest.h>
#include <algorithm> // for move
#include <complex>
#include <cstddef> // for std::ptrdiff_t
#include <functional> // for reference_wrapper, _Bind_helper<>::type
#include <gsl/narrow> // for narrow, narrowing_error
@ -144,5 +145,9 @@ TEST(utils_tests, narrow)
n = -42;
EXPECT_THROW(narrow<unsigned>(n), narrowing_error);
EXPECT_TRUE(
narrow<std::complex<float>>(std::complex<double>(4, 2)) == std::complex<float>(4, 2));
EXPECT_THROW(narrow<std::complex<float>>(std::complex<double>(4.2)), narrowing_error);
}
#endif // GSL_KERNEL_MODE