ceph/src/boost/libs/multiprecision/include/boost/multiprecision/traits/explicit_conversion.hpp

   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 {
  15    namespace multiprecision {
  16       namespace detail {
  17
  18          template <int N>
  19          struct dummy_size {};
  20
  21          template<typename S, typename T>
  22          struct has_generic_interconversion
  23          {
  24             typedef typename mpl::if_c <
  25                is_number<S>::value && is_number<T>::value,
  26                typename mpl::if_c <
  27                number_category<S>::value == number_kind_integer,
  28                typename mpl::if_c<
  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,
  33                mpl::true_,
  34                mpl::false_
  35                >::type,
  36                typename mpl::if_c<
  37                number_category<S>::value == number_kind_rational,
  38                typename mpl::if_c<
  39                number_category<T>::value == number_kind_rational
  40                || number_category<T>::value == number_kind_rational,
  41                mpl::true_,
  42                mpl::false_
  43                >::type,
  44                typename mpl::if_c<
  45                number_category<T>::value == number_kind_floating_point,
  46                mpl::true_,
  47                mpl::false_
  48                >::type
  49                >::type
  50                > ::type,
  51                mpl::false_
  52             > ::type type;
  53          };
  54
  55          template<typename S, typename T>
  56          struct is_explicitly_convertible_imp
  57          {
  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>()))>*);
  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 mpl::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 }}} // namespaces
  88
  89 #endif
  90