math/special_functions/trunc.hpp

0001 //  Copyright John Maddock 2007.
0002 //  Copyright Matt Borland 2023.
0003 //  Use, modification and distribution are subject to the
0004 //  Boost Software License, Version 1.0. (See accompanying file
0005 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_MATH_TRUNC_HPP
0008 #define BOOST_MATH_TRUNC_HPP
0009
0010 #ifdef _MSC_VER
0011 #pragma once
0012 #endif
0013
0014 #include <type_traits>
0015 #include <boost/math/special_functions/math_fwd.hpp>
0016 #include <boost/math/tools/config.hpp>
0017 #include <boost/math/ccmath/detail/config.hpp>
0018 #include <boost/math/policies/error_handling.hpp>
0019 #include <boost/math/special_functions/fpclassify.hpp>
0020 #include <boost/math/tools/is_constant_evaluated.hpp>
0021
0022 #if !defined(BOOST_MATH_NO_CCMATH) && !defined(BOOST_MATH_NO_CONSTEXPR_DETECTION)
0023 #include <boost/math/ccmath/ldexp.hpp>
0024 #    define BOOST_MATH_HAS_CONSTEXPR_LDEXP
0025 #endif
0026
0027 namespace boost{ namespace math{ namespace detail{
0028
0029 template <class T, class Policy>
0030 inline tools::promote_args_t<T> trunc(const T& v, const Policy& pol, const std::false_type&)
0031 {
0032    BOOST_MATH_STD_USING
0033    using result_type = tools::promote_args_t<T>;
0034    if(!(boost::math::isfinite)(v))
0035    {
0036       return policies::raise_rounding_error("boost::math::trunc<%1%>(%1%)", nullptr, static_cast<result_type>(v), static_cast<result_type>(v), pol);
0037    }
0038    return (v >= 0) ? static_cast<result_type>(floor(v)) : static_cast<result_type>(ceil(v));
0039 }
0040
0041 template <class T, class Policy>
0042 inline tools::promote_args_t<T> trunc(const T& v, const Policy&, const std::true_type&)
0043 {
0044    return v;
0045 }
0046
0047 }
0048
0049 template <class T, class Policy>
0050 inline tools::promote_args_t<T> trunc(const T& v, const Policy& pol)
0051 {
0052    return detail::trunc(v, pol, std::integral_constant<bool, detail::is_integer_for_rounding<T>::value>());
0053 }
0054 template <class T>
0055 inline tools::promote_args_t<T> trunc(const T& v)
0056 {
0057    return trunc(v, policies::policy<>());
0058 }
0059 //
0060 // The following functions will not compile unless T has an
0061 // implicit conversion to the integer types.  For user-defined
0062 // number types this will likely not be the case.  In that case
0063 // these functions should either be specialized for the UDT in
0064 // question, or else overloads should be placed in the same
0065 // namespace as the UDT: these will then be found via argument
0066 // dependent lookup.  See our concept archetypes for examples.
0067 //
0068 // Non-standard numeric limits syntax "(std::numeric_limits<int>::max)()"
0069 // is to avoid macro substiution from MSVC
0070 // https://stackoverflow.com/questions/27442885/syntax-error-with-stdnumeric-limitsmax
0071 //
0072 template <class T, class Policy>
0073 inline int itrunc(const T& v, const Policy& pol)
0074 {
0075    BOOST_MATH_STD_USING
0076    using result_type = tools::promote_args_t<T>;
0077    result_type r = boost::math::trunc(v, pol);
0078
0079    #ifdef BOOST_MATH_HAS_CONSTEXPR_LDEXP
0080    if constexpr (std::is_arithmetic_v<result_type>
0081                  #ifdef BOOST_MATH_FLOAT128_TYPE
0082                  && !std::is_same_v<BOOST_MATH_FLOAT128_TYPE, result_type>
0083                  #endif
0084                 )
0085    {
0086       constexpr result_type max_val = boost::math::ccmath::ldexp(static_cast<result_type>(1), std::numeric_limits<int>::digits);
0087
0088       if (r >= max_val || r < -max_val)
0089       {
0090          return static_cast<int>(boost::math::policies::raise_rounding_error("boost::math::itrunc<%1%>(%1%)", nullptr, v, static_cast<int>(0), pol));
0091       }
0092    }
0093    else
0094    {
0095       static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<int>::digits);
0096
0097       if (r >= max_val || r < -max_val)
0098       {
0099          return static_cast<int>(boost::math::policies::raise_rounding_error("boost::math::itrunc<%1%>(%1%)", nullptr, v, static_cast<int>(0), pol));
0100       }
0101    }
0102    #else
0103    static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<int>::digits);
0104
0105    if (r >= max_val || r < -max_val)
0106    {
0107       return static_cast<int>(boost::math::policies::raise_rounding_error("boost::math::itrunc<%1%>(%1%)", nullptr, v, static_cast<int>(0), pol));
0108    }
0109    #endif
0110
0111    return static_cast<int>(r);
0112 }
0113 template <class T>
0114 inline int itrunc(const T& v)
0115 {
0116    return itrunc(v, policies::policy<>());
0117 }
0118
0119 template <class T, class Policy>
0120 inline long ltrunc(const T& v, const Policy& pol)
0121 {
0122    BOOST_MATH_STD_USING
0123    using result_type = tools::promote_args_t<T>;
0124    result_type r = boost::math::trunc(v, pol);
0125
0126    #ifdef BOOST_MATH_HAS_CONSTEXPR_LDEXP
0127    if constexpr (std::is_arithmetic_v<result_type>
0128                  #ifdef BOOST_MATH_FLOAT128_TYPE
0129                  && !std::is_same_v<BOOST_MATH_FLOAT128_TYPE, result_type>
0130                  #endif
0131                 )
0132    {
0133       constexpr result_type max_val = boost::math::ccmath::ldexp(static_cast<result_type>(1), std::numeric_limits<long>::digits);
0134
0135       if (r >= max_val || r < -max_val)
0136       {
0137          return static_cast<long>(boost::math::policies::raise_rounding_error("boost::math::ltrunc<%1%>(%1%)", nullptr, v, static_cast<long>(0), pol));
0138       }
0139    }
0140    else
0141    {
0142       static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<long>::digits);
0143
0144       if (r >= max_val || r < -max_val)
0145       {
0146          return static_cast<long>(boost::math::policies::raise_rounding_error("boost::math::ltrunc<%1%>(%1%)", nullptr, v, static_cast<long>(0), pol));
0147       }
0148    }
0149    #else
0150    static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<long>::digits);
0151
0152    if (r >= max_val || r < -max_val)
0153    {
0154       return static_cast<long>(boost::math::policies::raise_rounding_error("boost::math::ltrunc<%1%>(%1%)", nullptr, v, static_cast<long>(0), pol));
0155    }
0156    #endif
0157
0158    return static_cast<long>(r);
0159 }
0160 template <class T>
0161 inline long ltrunc(const T& v)
0162 {
0163    return ltrunc(v, policies::policy<>());
0164 }
0165
0166 template <class T, class Policy>
0167 inline long long lltrunc(const T& v, const Policy& pol)
0168 {
0169    BOOST_MATH_STD_USING
0170    using result_type = tools::promote_args_t<T>;
0171    result_type r = boost::math::trunc(v, pol);
0172
0173    #ifdef BOOST_MATH_HAS_CONSTEXPR_LDEXP
0174    if constexpr (std::is_arithmetic_v<result_type>
0175                  #ifdef BOOST_MATH_FLOAT128_TYPE
0176                  && !std::is_same_v<BOOST_MATH_FLOAT128_TYPE, result_type>
0177                  #endif
0178                 )
0179    {
0180       constexpr result_type max_val = boost::math::ccmath::ldexp(static_cast<result_type>(1), std::numeric_limits<long long>::digits);
0181
0182       if (r >= max_val || r < -max_val)
0183       {
0184          return static_cast<long long>(boost::math::policies::raise_rounding_error("boost::math::lltrunc<%1%>(%1%)", nullptr, v, static_cast<long long>(0), pol));
0185       }
0186    }
0187    else
0188    {
0189       static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<long long>::digits);
0190
0191       if (r >= max_val || r < -max_val)
0192       {
0193          return static_cast<long long>(boost::math::policies::raise_rounding_error("boost::math::lltrunc<%1%>(%1%)", nullptr, v, static_cast<long long>(0), pol));
0194       }
0195    }
0196    #else
0197    static const result_type max_val = ldexp(static_cast<result_type>(1), std::numeric_limits<long long>::digits);
0198
0199    if (r >= max_val || r < -max_val)
0200    {
0201       return static_cast<long long>(boost::math::policies::raise_rounding_error("boost::math::lltrunc<%1%>(%1%)", nullptr, v, static_cast<long long>(0), pol));
0202    }
0203    #endif
0204
0205    return static_cast<long long>(r);
0206 }
0207 template <class T>
0208 inline long long lltrunc(const T& v)
0209 {
0210    return lltrunc(v, policies::policy<>());
0211 }
0212
0213 template <class T, class Policy>
0214 inline typename std::enable_if<std::is_constructible<int, T>::value, int>::type
0215    iconvert(const T& v, const Policy&)
0216 {
0217    return static_cast<int>(v);
0218 }
0219
0220 template <class T, class Policy>
0221 inline typename std::enable_if<!std::is_constructible<int, T>::value, int>::type
0222    iconvert(const T& v, const Policy& pol)
0223 {
0224    using boost::math::itrunc;
0225    return itrunc(v, pol);
0226 }
0227
0228 template <class T, class Policy>
0229 inline typename std::enable_if<std::is_constructible<long, T>::value, long>::type
0230    lconvert(const T& v, const Policy&)
0231 {
0232    return static_cast<long>(v);
0233 }
0234
0235 template <class T, class Policy>
0236 inline typename std::enable_if<!std::is_constructible<long, T>::value, long>::type
0237    lconvert(const T& v, const Policy& pol)
0238 {
0239    using boost::math::ltrunc;
0240    return ltrunc(v, pol);
0241 }
0242
0243 template <class T, class Policy>
0244 inline typename std::enable_if<std::is_constructible<long long, T>::value, long long>::type
0245    llconvertert(const T& v, const Policy&)
0246 {
0247    return static_cast<long long>(v);
0248 }
0249
0250 template <class T, class Policy>
0251 inline typename std::enable_if<!std::is_constructible<long long, T>::value, long long>::type
0252    llconvertert(const T& v, const Policy& pol)
0253 {
0254    using boost::math::lltrunc;
0255    return lltrunc(v, pol);
0256 }
0257
0258 }} // namespaces
0259
0260 #endif // BOOST_MATH_TRUNC_HPP