91 lines
3.2 KiB
Plaintext
91 lines
3.2 KiB
Plaintext
///////////////////////////////////////////////////////////////////////////////
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// Copyright Vicente J. Botet Escriba 2009-2011
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// Copyright 2012 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
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#define BOOST_MP_EXPLICIT_CONVERTIBLE_HPP
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#include <boost/type_traits/is_convertible.hpp>
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#include <boost/utility/declval.hpp>
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namespace boost {
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namespace multiprecision {
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namespace detail {
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template <int N>
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struct dummy_size {};
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template<typename S, typename T>
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struct has_generic_interconversion
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{
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typedef typename mpl::if_c <
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is_number<S>::value && is_number<T>::value,
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typename mpl::if_c <
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number_category<S>::value == number_kind_integer,
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typename mpl::if_c<
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number_category<T>::value == number_kind_integer
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|| number_category<T>::value == number_kind_floating_point
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|| number_category<T>::value == number_kind_rational
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|| number_category<T>::value == number_kind_fixed_point,
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mpl::true_,
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mpl::false_
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>::type,
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typename mpl::if_c<
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number_category<S>::value == number_kind_rational,
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typename mpl::if_c<
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number_category<T>::value == number_kind_rational
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|| number_category<T>::value == number_kind_rational,
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mpl::true_,
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mpl::false_
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>::type,
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typename mpl::if_c<
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number_category<T>::value == number_kind_floating_point,
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mpl::true_,
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mpl::false_
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>::type
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>::type
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> ::type,
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mpl::false_
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> ::type type;
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};
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template<typename S, typename T>
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struct is_explicitly_convertible_imp
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{
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#ifndef BOOST_NO_SFINAE_EXPR
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template<typename S1, typename T1>
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static type_traits::yes_type selector(dummy_size<sizeof(static_cast<T1>(declval<S1>()))>*);
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template<typename S1, typename T1>
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static type_traits::no_type selector(...);
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static const bool value = sizeof(selector<S, T>(0)) == sizeof(type_traits::yes_type);
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typedef boost::integral_constant<bool, value> type;
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#else
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typedef typename has_generic_interconversion<S, T>::type gen_type;
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typedef mpl::bool_<boost::is_convertible<S, T>::value || gen_type::value> type;
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#endif
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};
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template<typename From, typename To>
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struct is_explicitly_convertible : public is_explicitly_convertible_imp<From, To>::type
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{
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};
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#ifdef BOOST_NO_SFINAE_EXPR
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template<class Backend1, expression_template_option ExpressionTemplates1, class Backend2, expression_template_option ExpressionTemplates2>
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struct is_explicitly_convertible<number<Backend1, ExpressionTemplates1>, number<Backend2, ExpressionTemplates2> >
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: public is_explicitly_convertible<Backend1, Backend2>
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{
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};
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#endif
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}}} // namespaces
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#endif
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