| |
| // (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> |
| |
| 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)>{}; |
| 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>{}; |
| 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 |