| // boost\math\tools\promotion.hpp |
| |
| // Copyright John Maddock 2006. |
| // Copyright Paul A. Bristow 2006. |
| |
| // 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) |
| |
| // Promote arguments functions to allow math functions to have arguments |
| // provided as integer OR real (floating-point, built-in or UDT) |
| // (called ArithmeticType in functions that use promotion) |
| // that help to reduce the risk of creating multiple instantiations. |
| // Allows creation of an inline wrapper that forwards to a foo(RT, RT) function, |
| // so you never get to instantiate any mixed foo(RT, IT) functions. |
| |
| #ifndef BOOST_MATH_PROMOTION_HPP |
| #define BOOST_MATH_PROMOTION_HPP |
| |
| #ifdef _MSC_VER |
| #pragma once |
| #endif |
| |
| // Boost type traits: |
| #include <boost/math/tools/config.hpp> |
| #include <boost/type_traits/is_floating_point.hpp> // for boost::is_floating_point; |
| #include <boost/type_traits/is_integral.hpp> // for boost::is_integral |
| #include <boost/type_traits/is_convertible.hpp> // for boost::is_convertible |
| #include <boost/type_traits/is_same.hpp>// for boost::is_same |
| #include <boost/type_traits/remove_cv.hpp>// for boost::remove_cv |
| // Boost Template meta programming: |
| #include <boost/mpl/if.hpp> // for boost::mpl::if_c. |
| #include <boost/mpl/and.hpp> // for boost::mpl::if_c. |
| #include <boost/mpl/or.hpp> // for boost::mpl::if_c. |
| |
| #ifdef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS |
| #include <boost/static_assert.hpp> |
| #endif |
| |
| namespace boost |
| { |
| namespace math |
| { |
| namespace tools |
| { |
| // If either T1 or T2 is an integer type, |
| // pretend it was a double (for the purposes of further analysis). |
| // Then pick the wider of the two floating-point types |
| // as the actual signature to forward to. |
| // For example: |
| // foo(int, short) -> double foo(double, double); |
| // foo(int, float) -> double foo(double, double); |
| // Note: NOT float foo(float, float) |
| // foo(int, double) -> foo(double, double); |
| // foo(double, float) -> double foo(double, double); |
| // foo(double, float) -> double foo(double, double); |
| // foo(any-int-or-float-type, long double) -> foo(long double, long double); |
| // but ONLY float foo(float, float) is unchanged. |
| // So the only way to get an entirely float version is to call foo(1.F, 2.F), |
| // But since most (all?) the math functions convert to double internally, |
| // probably there would not be the hoped-for gain by using float here. |
| |
| // This follows the C-compatible conversion rules of pow, etc |
| // where pow(int, float) is converted to pow(double, double). |
| |
| template <class T> |
| struct promote_arg |
| { // If T is integral type, then promote to double. |
| typedef typename mpl::if_<is_integral<T>, double, T>::type type; |
| }; |
| // These full specialisations reduce mpl::if_ usage and speed up |
| // compilation: |
| template <> struct promote_arg<float> { typedef float type; }; |
| template <> struct promote_arg<double>{ typedef double type; }; |
| template <> struct promote_arg<long double> { typedef long double type; }; |
| template <> struct promote_arg<int> { typedef double type; }; |
| |
| template <class T1, class T2> |
| struct promote_args_2 |
| { // Promote, if necessary, & pick the wider of the two floating-point types. |
| // for both parameter types, if integral promote to double. |
| typedef typename promote_arg<T1>::type T1P; // T1 perhaps promoted. |
| typedef typename promote_arg<T2>::type T2P; // T2 perhaps promoted. |
| |
| typedef typename mpl::if_< |
| typename mpl::and_<is_floating_point<T1P>, is_floating_point<T2P> >::type, // both T1P and T2P are floating-point? |
| typename mpl::if_< typename mpl::or_<is_same<long double, T1P>, is_same<long double, T2P> >::type, // either long double? |
| long double, // then result type is long double. |
| typename mpl::if_< typename mpl::or_<is_same<double, T1P>, is_same<double, T2P> >::type, // either double? |
| double, // result type is double. |
| float // else result type is float. |
| >::type |
| >::type, |
| // else one or the other is a user-defined type: |
| typename mpl::if_< ::boost::is_convertible<T1P, T2P>, T2P, T1P>::type>::type type; |
| }; // promote_arg2 |
| // These full specialisations reduce mpl::if_ usage and speed up |
| // compilation: |
| template <> struct promote_args_2<float, float> { typedef float type; }; |
| template <> struct promote_args_2<double, double>{ typedef double type; }; |
| template <> struct promote_args_2<long double, long double> { typedef long double type; }; |
| template <> struct promote_args_2<int, int> { typedef double type; }; |
| template <> struct promote_args_2<int, float> { typedef double type; }; |
| template <> struct promote_args_2<float, int> { typedef double type; }; |
| template <> struct promote_args_2<int, double> { typedef double type; }; |
| template <> struct promote_args_2<double, int> { typedef double type; }; |
| template <> struct promote_args_2<int, long double> { typedef long double type; }; |
| template <> struct promote_args_2<long double, int> { typedef long double type; }; |
| template <> struct promote_args_2<float, double> { typedef double type; }; |
| template <> struct promote_args_2<double, float> { typedef double type; }; |
| template <> struct promote_args_2<float, long double> { typedef long double type; }; |
| template <> struct promote_args_2<long double, float> { typedef long double type; }; |
| template <> struct promote_args_2<double, long double> { typedef long double type; }; |
| template <> struct promote_args_2<long double, double> { typedef long double type; }; |
| |
| template <class T1, class T2=float, class T3=float, class T4=float, class T5=float, class T6=float> |
| struct promote_args |
| { |
| typedef typename promote_args_2< |
| typename remove_cv<T1>::type, |
| typename promote_args_2< |
| typename remove_cv<T2>::type, |
| typename promote_args_2< |
| typename remove_cv<T3>::type, |
| typename promote_args_2< |
| typename remove_cv<T4>::type, |
| typename promote_args_2< |
| typename remove_cv<T5>::type, typename remove_cv<T6>::type |
| >::type |
| >::type |
| >::type |
| >::type |
| >::type type; |
| |
| #ifdef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS |
| // |
| // Guard against use of long double if it's not supported: |
| // |
| BOOST_STATIC_ASSERT((0 == ::boost::is_same<type, long double>::value)); |
| #endif |
| }; |
| |
| } // namespace tools |
| } // namespace math |
| } // namespace boost |
| |
| #endif // BOOST_MATH_PROMOTION_HPP |
| |
