Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: //  Copyright Vicente J. Botet Escriba 2009-2011
Chris@16: //  Copyright 2012 John Maddock. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
Chris@16: #define BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
Chris@16: 
Chris@16: #include <boost/type_traits/is_convertible.hpp>
Chris@16: #include <boost/utility/declval.hpp>
Chris@16: 
Chris@16: 
Chris@16: namespace boost{ namespace multiprecision{ namespace detail{
Chris@16: 
Chris@16: template <int N>
Chris@16: struct dummy_size{};
Chris@16: 
Chris@16: template<typename S, typename T>
Chris@16: struct has_generic_interconversion
Chris@16: {
Chris@16:    typedef typename mpl::if_c<
Chris@16:       is_number<S>::value && is_number<T>::value,
Chris@16:       typename mpl::if_c<
Chris@16:          number_category<S>::value == number_kind_integer,
Chris@16:          typename mpl::if_c<
Chris@16:             number_category<T>::value == number_kind_integer 
Chris@16:             || number_category<T>::value == number_kind_floating_point
Chris@16:             || number_category<T>::value == number_kind_rational
Chris@16:             || number_category<T>::value == number_kind_fixed_point,
Chris@16:             mpl::true_, 
Chris@16:             mpl::false_
Chris@16:          >::type,
Chris@16:          typename mpl::if_c<
Chris@16:             number_category<S>::value == number_kind_rational,
Chris@16:             typename mpl::if_c<
Chris@16:                number_category<T>::value == number_kind_rational
Chris@16:                || number_category<T>::value == number_kind_rational,
Chris@16:                mpl::true_,
Chris@16:                mpl::false_
Chris@16:             >::type,
Chris@16:             typename mpl::if_c<
Chris@16:                number_category<T>::value == number_kind_floating_point,
Chris@16:                mpl::true_,
Chris@16:                mpl::false_
Chris@16:             >::type
Chris@16:          >::type
Chris@16:       >::type,
Chris@16:       mpl::false_
Chris@16:    >::type type;
Chris@16: };
Chris@16: 
Chris@16: template<typename S, typename T>
Chris@16: struct is_explicitly_convertible_imp
Chris@16: {
Chris@16: #ifndef BOOST_NO_SFINAE_EXPR
Chris@16:    template<typename S1, typename T1>
Chris@16:    static type_traits::yes_type selector(dummy_size<sizeof(static_cast<T1>(declval<S1>()))>*);
Chris@16: 
Chris@16:    template<typename S1, typename T1>
Chris@16:    static type_traits::no_type selector(...);
Chris@16: 
Chris@16:    static const bool value = sizeof(selector<S,T>(0)) == sizeof(type_traits::yes_type);
Chris@16: 
Chris@16:    typedef boost::integral_constant<bool,value> type;
Chris@16: #else
Chris@16:    typedef typename has_generic_interconversion<S, T>::type gen_type;
Chris@16:    typedef mpl::bool_<boost::is_convertible<S, T>::value || gen_type::value> type;
Chris@16: #endif
Chris@16: };
Chris@16: 
Chris@16: template<typename From, typename To>
Chris@16: struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type
Chris@16: {
Chris@16: };
Chris@16: 
Chris@16: }}} // namespaces
Chris@16: 
Chris@16: #endif
Chris@16: