1 /////////////////////////////////////////////////////////////////////////////// 2 // Copyright Vicente J. Botet Escriba 2009-2011 3 // Copyright 2012 John Maddock. Distributed under the Boost 4 // Software License, Version 1.0. (See accompanying file 5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 7 #ifndef BOOST_MP_EXPLICIT_CONVERTIBLE_HPP 8 #define BOOST_MP_EXPLICIT_CONVERTIBLE_HPP 9 10 #include <boost/config.hpp> 11 #include <boost/type_traits/conditional.hpp> 12 #include <boost/type_traits/integral_constant.hpp> 13 #include <boost/type_traits/is_convertible.hpp> 14 #include <boost/type_traits/declval.hpp> 15 #include <boost/multiprecision/detail/number_base.hpp> // number_category 16 17 namespace boost { 18 namespace multiprecision { 19 namespace detail { 20 21 template <unsigned int N> 22 struct dummy_size 23 {}; 24 25 template <typename S, typename T> 26 struct has_generic_interconversion 27 { 28 typedef typename boost::conditional< 29 is_number<S>::value && is_number<T>::value, 30 typename boost::conditional< 31 number_category<S>::value == number_kind_integer, 32 typename boost::conditional< 33 number_category<T>::value == number_kind_integer || number_category<T>::value == number_kind_floating_point || number_category<T>::value == number_kind_rational || number_category<T>::value == number_kind_fixed_point, 34 boost::true_type, 35 boost::false_type>::type, 36 typename boost::conditional< 37 number_category<S>::value == number_kind_rational, 38 typename boost::conditional< 39 number_category<T>::value == number_kind_rational || number_category<T>::value == number_kind_rational, 40 boost::true_type, 41 boost::false_type>::type, 42 typename boost::conditional< 43 number_category<T>::value == number_kind_floating_point, 44 boost::true_type, 45 boost::false_type>::type>::type>::type, 46 boost::false_type>::type type; 47 }; 48 49 template <typename S, typename T> 50 struct is_explicitly_convertible_imp 51 { 52 #ifndef BOOST_NO_SFINAE_EXPR 53 template <typename S1, typename T1> 54 static type_traits::yes_type selector(dummy_size<sizeof(new T1(boost::declval< 55 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) 56 S1 57 #else 58 S1 const& 59 #endif 60 >()))>*); 61 62 template <typename S1, typename T1> 63 static type_traits::no_type selector(...); 64 65 static const bool value = sizeof(selector<S, T>(0)) == sizeof(type_traits::yes_type); 66 67 typedef boost::integral_constant<bool, value> type; 68 #else 69 typedef typename has_generic_interconversion<S, T>::type gen_type; 70 typedef boost::integral_constant<bool, boost::is_convertible<S, T>::value || gen_type::value> type; 71 #endif 72 }; 73 74 template <typename From, typename To> 75 struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type 76 { 77 }; 78 79 #ifdef BOOST_NO_SFINAE_EXPR 80 template <class Backend1, expression_template_option ExpressionTemplates1, class Backend2, expression_template_option ExpressionTemplates2> 81 struct is_explicitly_convertible<number<Backend1, ExpressionTemplates1>, number<Backend2, ExpressionTemplates2> > 82 : public is_explicitly_convertible<Backend1, Backend2> 83 { 84 }; 85 #endif 86 87 }}} // namespace boost::multiprecision::detail 88 89 #endif 90