1 /////////////////////////////////////////////////////////////////////////////// 2 // Copyright 2015 John Maddock. Distributed under the Boost 3 // Software License, Version 1.0. (See accompanying file 4 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 5 6 #ifndef BOOST_MP_IS_BACKEND_HPP 7 #define BOOST_MP_IS_BACKEND_HPP 8 9 #include <boost/mpl/has_xxx.hpp> 10 #include <boost/type_traits/conditional.hpp> 11 #include <boost/type_traits/is_convertible.hpp> 12 #include <boost/multiprecision/detail/number_base.hpp> 13 14 namespace boost { namespace multiprecision { namespace detail { 15 16 BOOST_MPL_HAS_XXX_TRAIT_DEF(signed_types) 17 BOOST_MPL_HAS_XXX_TRAIT_DEF(unsigned_types) 18 BOOST_MPL_HAS_XXX_TRAIT_DEF(float_types) 19 20 template <class T> 21 struct is_backend 22 { 23 static const bool value = has_signed_types<T>::value && has_unsigned_types<T>::value && has_float_types<T>::value; 24 }; 25 26 template <class Backend> 27 struct other_backend 28 { 29 typedef typename boost::conditional< 30 boost::is_same<number<Backend>, number<Backend, et_on> >::value, 31 number<Backend, et_off>, number<Backend, et_on> >::type type; 32 }; 33 34 template <class B, class V> 35 struct number_from_backend 36 { 37 typedef typename boost::conditional< 38 boost::is_convertible<V, number<B> >::value, 39 number<B>, 40 typename other_backend<B>::type>::type type; 41 }; 42 43 template <bool b, class T, class U> 44 struct is_first_backend_imp 45 { 46 static const bool value = false; 47 }; 48 template <class T, class U> 49 struct is_first_backend_imp<true, T, U> 50 { 51 static const bool value = is_convertible<U, number<T, et_on> >::value || is_convertible<U, number<T, et_off> >::value; 52 }; 53 54 template <class T, class U> 55 struct is_first_backend : is_first_backend_imp<is_backend<T>::value, T, U> 56 {}; 57 58 template <bool b, class T, class U> 59 struct is_second_backend_imp 60 { 61 static const bool value = false; 62 }; 63 template <class T, class U> 64 struct is_second_backend_imp<true, T, U> 65 { 66 static const bool value = (is_convertible<T, number<U, et_on> >::value || is_convertible<T, number<U, et_off> >::value) && !is_first_backend<T, U>::value; 67 }; 68 69 template <class T, class U> 70 struct is_second_backend : is_second_backend_imp<is_backend<U>::value, T, U> 71 {}; 72 73 } 74 } 75 } // namespace boost::multiprecision::detail 76 77 #endif // BOOST_MP_IS_BACKEND_HPP 78