math/ccmath/trunc.hpp

0001 //  (C) Copyright Matt Borland 2021.
0002 //  Use, modification and distribution are subject to the
0003 //  Boost Software License, Version 1.0. (See accompanying file
0004 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_MATH_CCMATH_TRUNC_HPP
0007 #define BOOST_MATH_CCMATH_TRUNC_HPP
0008
0009 #include <boost/math/ccmath/detail/config.hpp>
0010
0011 #ifdef BOOST_MATH_NO_CCMATH
0012 #error "The header <boost/math/trunc.hpp> can only be used in C++17 and later."
0013 #endif
0014
0015 #include <boost/math/ccmath/abs.hpp>
0016 #include <boost/math/ccmath/isinf.hpp>
0017 #include <boost/math/ccmath/isnan.hpp>
0018 #include <boost/math/ccmath/floor.hpp>
0019 #include <boost/math/ccmath/ceil.hpp>
0020
0021 namespace boost::math::ccmath {
0022
0023 namespace detail {
0024
0025 template <typename T>
0026 inline constexpr T trunc_impl(T arg) noexcept
0027 {
0028     return (arg > 0) ? boost::math::ccmath::floor(arg) : boost::math::ccmath::ceil(arg);
0029 }
0030
0031 } // Namespace detail
0032
0033 template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
0034 inline constexpr Real trunc(Real arg) noexcept
0035 {
0036     if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
0037     {
0038         return boost::math::ccmath::abs(arg) == Real(0) ? arg :
0039                boost::math::ccmath::isinf(arg) ? arg :
0040                boost::math::ccmath::isnan(arg) ? arg :
0041                boost::math::ccmath::detail::trunc_impl(arg);
0042     }
0043     else
0044     {
0045         using std::trunc;
0046         return trunc(arg);
0047     }
0048 }
0049
0050 template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
0051 inline constexpr double trunc(Z arg) noexcept
0052 {
0053     return boost::math::ccmath::trunc(static_cast<double>(arg));
0054 }
0055
0056 inline constexpr float truncf(float arg) noexcept
0057 {
0058     return boost::math::ccmath::trunc(arg);
0059 }
0060
0061 #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
0062 inline constexpr long double truncl(long double arg) noexcept
0063 {
0064     return boost::math::ccmath::trunc(arg);
0065 }
0066 #endif
0067
0068 } // Namespaces
0069
0070 #endif // BOOST_MATH_CCMATH_TRUNC_HPP