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)
7 #ifndef BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
8 #define BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
10 #include <boost/type_traits/is_convertible.hpp>
11 #include <boost/utility/declval.hpp>
15 namespace multiprecision {
21 template<typename S, typename T>
22 struct has_generic_interconversion
24 typedef typename mpl::if_c <
25 is_number<S>::value && is_number<T>::value,
27 number_category<S>::value == number_kind_integer,
29 number_category<T>::value == number_kind_integer
30 || number_category<T>::value == number_kind_floating_point
31 || number_category<T>::value == number_kind_rational
32 || number_category<T>::value == number_kind_fixed_point,
37 number_category<S>::value == number_kind_rational,
39 number_category<T>::value == number_kind_rational
40 || number_category<T>::value == number_kind_rational,
45 number_category<T>::value == number_kind_floating_point,
55 template<typename S, typename T>
56 struct is_explicitly_convertible_imp
58 #ifndef BOOST_NO_SFINAE_EXPR
59 template<typename S1, typename T1>
60 static type_traits::yes_type selector(dummy_size<sizeof(static_cast<T1>(declval<S1>()))>*);
62 template<typename S1, typename T1>
63 static type_traits::no_type selector(...);
65 static const bool value = sizeof(selector<S, T>(0)) == sizeof(type_traits::yes_type);
67 typedef boost::integral_constant<bool, value> type;
69 typedef typename has_generic_interconversion<S, T>::type gen_type;
70 typedef mpl::bool_<boost::is_convertible<S, T>::value || gen_type::value> type;
74 template<typename From, typename To>
75 struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type
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>