2 // (C) Copyright John Maddock 2015.
3 // Use, modification and distribution are subject to the Boost Software License,
4 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5 // http://www.boost.org/LICENSE_1_0.txt).
7 // See http://www.boost.org/libs/type_traits for most recent version including documentation.
9 #ifndef BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
10 #define BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
12 #include <cstddef> // size_t
13 #include <boost/type_traits/integral_constant.hpp>
14 #include <boost/detail/workaround.hpp>
16 #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
17 #include <boost/type_traits/is_abstract.hpp>
20 #if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
22 #include <boost/type_traits/detail/yes_no_type.hpp>
28 struct is_default_constructible_imp
30 template<typename _Tp, typename = decltype(_Tp())>
31 static boost::type_traits::yes_type test(int);
34 static boost::type_traits::no_type test(...);
36 #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
37 template<class T, bool b>
38 struct is_default_constructible_abstract_filter
40 static const bool value = sizeof(is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type);
43 struct is_default_constructible_abstract_filter<T, true>
45 static const bool value = false;
50 #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
51 template <class T> struct is_default_constructible : public integral_constant<bool, detail::is_default_constructible_abstract_filter<T, boost::is_abstract<T>::value>::value>{};
53 template <class T> struct is_default_constructible : public integral_constant<bool, sizeof(detail::is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type)>{};
55 template <class T, std::size_t N> struct is_default_constructible<T[N]> : public is_default_constructible<T>{};
56 template <class T> struct is_default_constructible<T[]> : public is_default_constructible<T>{};
57 template <class T> struct is_default_constructible<T&> : public integral_constant<bool, false>{};
58 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
59 template <class T> struct is_default_constructible<T&&> : public integral_constant<bool, false>{};
61 template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
62 template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
63 template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
64 template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
68 #include <boost/type_traits/is_pod.hpp>
72 // We don't know how to implement this, note we can not use has_trivial_constructor here
73 // because the correct implementation of that trait requires this one:
74 template <class T> struct is_default_constructible : public is_pod<T>{};
75 template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
76 template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
77 template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
78 template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
84 #endif // BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED