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///////////////////////////////////////////////////////////////////////////////
// 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_EXPLICIT_CONVERTIBLE_HPP
#define BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
#include <boost/type_traits/is_convertible.hpp>
#include <boost/utility/declval.hpp>
namespace boost {
namespace multiprecision {
namespace detail {
template <int N>
struct dummy_size {};
template<typename S, typename T>
struct has_generic_interconversion
{
typedef typename mpl::if_c <
is_number<S>::value && is_number<T>::value,
typename mpl::if_c <
number_category<S>::value == number_kind_integer,
typename mpl::if_c<
number_category<T>::value == number_kind_integer
|| number_category<T>::value == number_kind_floating_point
|| number_category<T>::value == number_kind_rational
|| number_category<T>::value == number_kind_fixed_point,
mpl::true_,
mpl::false_
>::type,
typename mpl::if_c<
number_category<S>::value == number_kind_rational,
typename mpl::if_c<
number_category<T>::value == number_kind_rational
|| number_category<T>::value == number_kind_rational,
mpl::true_,
mpl::false_
>::type,
typename mpl::if_c<
number_category<T>::value == number_kind_floating_point,
mpl::true_,
mpl::false_
>::type
>::type
> ::type,
mpl::false_
> ::type type;
};
template<typename S, typename T>
struct is_explicitly_convertible_imp
{
#ifndef BOOST_NO_SFINAE_EXPR
template<typename S1, typename T1>
static type_traits::yes_type selector(dummy_size<sizeof(static_cast<T1>(declval<S1>()))>*);
template<typename S1, typename T1>
static type_traits::no_type selector(...);
static const bool value = sizeof(selector<S, T>(0)) == sizeof(type_traits::yes_type);
typedef boost::integral_constant<bool, value> type;
#else
typedef typename has_generic_interconversion<S, T>::type gen_type;
typedef mpl::bool_<boost::is_convertible<S, T>::value || gen_type::value> type;
#endif
};
template<typename From, typename To>
struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type
{
};
#ifdef BOOST_NO_SFINAE_EXPR
template<class Backend1, expression_template_option ExpressionTemplates1, class Backend2, expression_template_option ExpressionTemplates2>
struct is_explicitly_convertible<number<Backend1, ExpressionTemplates1>, number<Backend2, ExpressionTemplates2> >
: public is_explicitly_convertible<Backend1, Backend2>
{
};
#endif
}}} // namespaces
#endif
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