77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
// (C) Copyright Matt Borland 2021.
|
|
// Use, modification and distribution are subject to the
|
|
// Boost Software License, Version 1.0. (See accompanying file
|
|
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
//
|
|
// Constepxr implementation of abs (see c.math.abs secion 26.8.2 of the ISO standard)
|
|
|
|
#ifndef BOOST_MATH_CCMATH_ABS
|
|
#define BOOST_MATH_CCMATH_ABS
|
|
|
|
#include <cmath>
|
|
#include <type_traits>
|
|
#include <limits>
|
|
#include <boost/math/tools/is_constant_evaluated.hpp>
|
|
#include <boost/math/ccmath/isnan.hpp>
|
|
#include <boost/math/ccmath/isinf.hpp>
|
|
|
|
namespace boost::math::ccmath {
|
|
|
|
namespace detail {
|
|
|
|
template <typename T>
|
|
inline constexpr T abs_impl(T x) noexcept
|
|
{
|
|
return boost::math::ccmath::isnan(x) ? std::numeric_limits<T>::quiet_NaN() :
|
|
boost::math::ccmath::isinf(x) ? std::numeric_limits<T>::infinity() :
|
|
x == -0 ? T(0) :
|
|
x == (std::numeric_limits<T>::min)() ? std::numeric_limits<T>::quiet_NaN() :
|
|
x > 0 ? x : -x;
|
|
}
|
|
|
|
} // Namespace detail
|
|
|
|
template <typename T, std::enable_if_t<!std::is_unsigned_v<T>, bool> = true>
|
|
inline constexpr T abs(T x) noexcept
|
|
{
|
|
if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
|
|
{
|
|
return detail::abs_impl<T>(x);
|
|
}
|
|
else
|
|
{
|
|
using std::abs;
|
|
return abs(x);
|
|
}
|
|
}
|
|
|
|
// If abs() is called with an argument of type X for which is_unsigned_v<X> is true and if X
|
|
// cannot be converted to int by integral promotion (7.3.7), the program is ill-formed.
|
|
template <typename T, std::enable_if_t<std::is_unsigned_v<T>, bool> = true>
|
|
inline constexpr T abs(T x) noexcept
|
|
{
|
|
if constexpr (std::is_convertible_v<T, int>)
|
|
{
|
|
return detail::abs_impl<int>(static_cast<int>(x));
|
|
}
|
|
else
|
|
{
|
|
static_assert(sizeof(T) == 0, "Taking the absolute value of an unsigned value not covertible to int is UB.");
|
|
return T(0); // Unreachable, but suppresses warnings
|
|
}
|
|
}
|
|
|
|
inline constexpr long int labs(long int j) noexcept
|
|
{
|
|
return boost::math::ccmath::abs(j);
|
|
}
|
|
|
|
inline constexpr long long int llabs(long long int j) noexcept
|
|
{
|
|
return boost::math::ccmath::abs(j);
|
|
}
|
|
|
|
} // Namespaces
|
|
|
|
#endif // BOOST_MATH_CCMATH_ABS
|