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/type_traits/is_convertible.hpp> 11 #include <boost/utility/declval.hpp> 12 13 14 namespace boost{ namespace multiprecision{ namespace detail{ 15 16 template <int N> 17 struct dummy_size{}; 18 19 template<typename S, typename T> 20 struct has_generic_interconversion 21 { 22 typedef typename mpl::if_c< 23 is_number<S>::value && is_number<T>::value, 24 typename mpl::if_c< 25 number_category<S>::value == number_kind_integer, 26 typename mpl::if_c< 27 number_category<T>::value == number_kind_integer 28 || number_category<T>::value == number_kind_floating_point 29 || number_category<T>::value == number_kind_rational 30 || number_category<T>::value == number_kind_fixed_point, 31 mpl::true_, 32 mpl::false_ 33 >::type, 34 typename mpl::if_c< 35 number_category<S>::value == number_kind_rational, 36 typename mpl::if_c< 37 number_category<T>::value == number_kind_rational 38 || number_category<T>::value == number_kind_rational, 39 mpl::true_, 40 mpl::false_ 41 >::type, 42 typename mpl::if_c< 43 number_category<T>::value == number_kind_floating_point, 44 mpl::true_, 45 mpl::false_ 46 >::type 47 >::type 48 >::type, 49 mpl::false_ 50 >::type type; 51 }; 52 53 template<typename S, typename T> 54 struct is_explicitly_convertible_imp 55 { 56 #ifndef BOOST_NO_SFINAE_EXPR 57 template<typename S1, typename T1> 58 static type_traits::yes_type selector(dummy_size<sizeof(static_cast<T1>(declval<S1>()))>*); 59 60 template<typename S1, typename T1> 61 static type_traits::no_type selector(...); 62 63 static const bool value = sizeof(selector<S,T>(0)) == sizeof(type_traits::yes_type); 64 65 typedef boost::integral_constant<bool,value> type; 66 #else 67 typedef typename has_generic_interconversion<S, T>::type gen_type; 68 typedef mpl::bool_<boost::is_convertible<S, T>::value || gen_type::value> type; 69 #endif 70 }; 71 72 template<typename From, typename To> 73 struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type 74 { 75 }; 76 77 }}} // namespaces 78 79 #endif 80 81