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- // (C) Copyright John Maddock 2015.
- // Use, modification and distribution are subject to 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).
- //
- // See http://www.boost.org/libs/type_traits for most recent version including documentation.
- #ifndef BOOST_TT_IS_ASSIGNABLE_HPP_INCLUDED
- #define BOOST_TT_IS_ASSIGNABLE_HPP_INCLUDED
- #include <cstddef> // size_t
- #include <boost/type_traits/integral_constant.hpp>
- #include <boost/detail/workaround.hpp>
- #include <boost/type_traits/is_complete.hpp>
- #include <boost/static_assert.hpp>
- namespace boost{
- template <class T, class U = T> struct is_assignable;
- }
- #if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800)
- #include <boost/type_traits/detail/yes_no_type.hpp>
- #include <boost/type_traits/declval.hpp>
- namespace boost{
- namespace detail{
- struct is_assignable_imp
- {
- template<typename T, typename U, typename = decltype(boost::declval<T>() = boost::declval<U>())>
- static boost::type_traits::yes_type test(int);
- template<typename, typename>
- static boost::type_traits::no_type test(...);
- };
- }
- template <class T, class U> struct is_assignable : public integral_constant<bool, sizeof(detail::is_assignable_imp::test<T, U>(0)) == sizeof(boost::type_traits::yes_type)>
- {
- BOOST_STATIC_ASSERT_MSG(boost::is_complete<T>::value, "Arguments to is_assignable must be complete types");
- };
- template <class T, std::size_t N, class U> struct is_assignable<T[N], U> : public is_assignable<T, U>{};
- template <class T, std::size_t N, class U> struct is_assignable<T(&)[N], U> : public is_assignable<T&, U>{};
- template <class T, class U> struct is_assignable<T[], U> : public is_assignable<T, U>{};
- template <class T, class U> struct is_assignable<T(&)[], U> : public is_assignable<T&, U>{};
- template <class U> struct is_assignable<void, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void const, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void volatile, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void const volatile, U> : public integral_constant<bool, false>{};
- #else
- #include <boost/type_traits/has_trivial_assign.hpp>
- #include <boost/type_traits/remove_reference.hpp>
- namespace boost{
- // We don't know how to implement this:
- template <class T, class U> struct is_assignable : public integral_constant<bool, false>
- {
- BOOST_STATIC_ASSERT_MSG(boost::is_complete<T>::value, "Arguments to is_assignable must be complete types");
- };
- template <class T, class U> struct is_assignable<T&, U> : public integral_constant<bool, is_pod<T>::value && is_pod<typename remove_reference<U>::type>::value>{};
- template <class T, class U> struct is_assignable<const T&, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void const, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void volatile, U> : public integral_constant<bool, false>{};
- template <class U> struct is_assignable<void const volatile, U> : public integral_constant<bool, false>{};
- /*
- template <> struct is_assignable<void, void> : public integral_constant<bool, false>{};
- template <> struct is_assignable<void const, void const> : public integral_constant<bool, false>{};
- template <> struct is_assignable<void volatile, void volatile> : public integral_constant<bool, false>{};
- template <> struct is_assignable<void const volatile, void const volatile> : public integral_constant<bool, false>{};
- */
- #endif
- } // namespace boost
- #endif // BOOST_TT_IS_ASSIGNABLE_HPP_INCLUDED
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