Boost C++ Libraries

boost/multiprecision/traits/is_restricted_conversion.hpp

///////////////////////////////////////////////////////////////////////////////
//  Copyright Vicente J. Botet Escriba 2009-2011
//  Copyright 2012 John Maddock. Distributed under the Boost
//  Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_MP_IS_RESTRICTED_CONVERSION_HPP
#define BOOST_MP_IS_RESTRICTED_CONVERSION_HPP

#include <boost/multiprecision/traits/explicit_conversion.hpp>
#include <boost/multiprecision/detail/number_base.hpp>

namespace boost { namespace multiprecision { namespace detail {

template <class From, class To>
struct is_lossy_conversion
{
   static constexpr bool category_conditional_is_true =
         (   (static_cast<boost::multiprecision::number_category_type>(number_category<From>::value) == number_kind_floating_point)
          && (static_cast<boost::multiprecision::number_category_type>(number_category<To  >::value) == number_kind_integer))
      || (   (static_cast<boost::multiprecision::number_category_type>(number_category<From>::value) == number_kind_rational)
          && (static_cast<boost::multiprecision::number_category_type>(number_category<To  >::value) == number_kind_integer))
      || (   (static_cast<boost::multiprecision::number_category_type>(number_category<From>::value) == number_kind_fixed_point)
          && (static_cast<boost::multiprecision::number_category_type>(number_category<To  >::value) == number_kind_integer))
      ||     (static_cast<boost::multiprecision::number_category_type>(number_category<From>::value) == number_kind_unknown)
      ||     (static_cast<boost::multiprecision::number_category_type>(number_category<To  >::value) == number_kind_unknown);

   using type = typename std::conditional<category_conditional_is_true,
                                          std::integral_constant<bool, true>,
                                          std::integral_constant<bool, false>>::type;

   static constexpr bool value = type::value;
};

template <typename From, typename To>
struct is_restricted_conversion
{
   using type = typename std::conditional<
       ((is_explicitly_convertible<From, To>::value && !std::is_convertible<From, To>::value) || is_lossy_conversion<From, To>::value),
       std::integral_constant<bool, true>,
       std::integral_constant<bool, false>>::type;
   static constexpr const bool                     value = type::value;
};

}}} // namespace boost::multiprecision::detail

#endif // BOOST_MP_IS_RESTRICTED_CONVERSION_HPP