// (C) Copyright Ion Gaztanaga 2014. // // 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_COPY_ASSIGNABLE_HPP_INCLUDED #define BOOST_TT_IS_COPY_ASSIGNABLE_HPP_INCLUDED #include <boost/config.hpp> #include <boost/type_traits/detail/yes_no_type.hpp> #include <boost/type_traits/is_base_and_derived.hpp> #include <boost/noncopyable.hpp> #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) && !defined(BOOST_NO_CXX11_DECLTYPE) \ && !defined(BOOST_INTEL_CXX_VERSION) && \ !(defined(BOOST_MSVC) && _MSC_VER == 1800) #define BOOST_TT_CXX11_IS_COPY_ASSIGNABLE #include <boost/type_traits/declval.hpp> #else //For compilers without decltype #include <boost/type_traits/is_const.hpp> #include <boost/type_traits/is_array.hpp> #include <boost/type_traits/add_reference.hpp> #include <boost/type_traits/remove_reference.hpp> #endif namespace boost { namespace detail{ template <bool DerivedFromNoncopyable, class T> struct is_copy_assignable_impl2 { // Intel compiler has problems with SFINAE for copy constructors and deleted functions: // // error: function *function_name* cannot be referenced -- it is a deleted function // static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0); // ^ // // MSVC 12.0 (Visual 2013) has problems when the copy constructor has been deleted. See: // https://connect.microsoft.com/VisualStudio/feedback/details/800328/std-is-copy-constructible-is-broken #if defined(BOOST_TT_CXX11_IS_COPY_ASSIGNABLE) typedef boost::type_traits::yes_type yes_type; typedef boost::type_traits::no_type no_type; template <class U> static decltype(::boost::declval<U&>() = ::boost::declval<const U&>(), yes_type() ) test(int); template <class> static no_type test(...); static const bool value = sizeof(test<T>(0)) == sizeof(yes_type); #else static BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type produce(); template <class T1> static boost::type_traits::no_type test(T1&, typename T1::boost_move_no_copy_constructor_or_assign* = 0); static boost::type_traits::yes_type test(...); // If you see errors like this: // // `'T::operator=(const T&)' is private` // `boost/type_traits/is_copy_assignable.hpp:NN:M: error: within this context` // // then you are trying to call that macro for a structure defined like that: // // struct T { // ... // private: // T & operator=(const T &); // ... // }; // // To fix that you must modify your structure: // // // C++03 and C++11 version // struct T: private boost::noncopyable { // ... // private: // T & operator=(const T &); // ... // }; // // // C++11 version // struct T { // ... // private: // T& operator=(const T &) = delete; // ... // }; BOOST_STATIC_CONSTANT(bool, value = ( sizeof(test(produce())) == sizeof(boost::type_traits::yes_type) )); #endif }; template <class T> struct is_copy_assignable_impl2<true, T> { BOOST_STATIC_CONSTANT(bool, value = false); }; template <class T> struct is_copy_assignable_impl { #if !defined(BOOST_TT_CXX11_IS_COPY_ASSIGNABLE) //For compilers without decltype, at least return false on const types, arrays //types derived from boost::noncopyable and types defined as BOOST_MOVEABLE_BUT_NOT_COPYABLE typedef BOOST_DEDUCED_TYPENAME boost::remove_reference<T>::type unreferenced_t; BOOST_STATIC_CONSTANT(bool, value = ( boost::detail::is_copy_assignable_impl2< boost::is_base_and_derived<boost::noncopyable, T>::value || boost::is_const<unreferenced_t>::value || boost::is_array<unreferenced_t>::value ,T >::value )); #else BOOST_STATIC_CONSTANT(bool, value = ( boost::detail::is_copy_assignable_impl2< boost::is_base_and_derived<boost::noncopyable, T>::value,T >::value )); #endif }; } // namespace detail template <class T> struct is_copy_assignable : public integral_constant<bool, ::boost::detail::is_copy_assignable_impl<T>::value>{}; template <> struct is_copy_assignable<void> : public false_type{}; #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS template <> struct is_copy_assignable<void const> : public false_type{}; template <> struct is_copy_assignable<void const volatile> : public false_type{}; template <> struct is_copy_assignable<void volatile> : public false_type{}; #endif } // namespace boost #endif // BOOST_TT_IS_COPY_ASSIGNABLE_HPP_INCLUDED