1
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).
6//
7// See http://www.boost.org/libs/type_traits for most recent version including documentation.
8
9#ifndef BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
10#define BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
11
12#include <boost/type_traits/integral_constant.hpp>
13#include <boost/detail/workaround.hpp>
14
15#if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
16
17#include <boost/type_traits/detail/yes_no_type.hpp>
18
19namespace boost{
20
21 namespace detail{
22
23 struct is_default_constructible_imp
24 {
25 template<typename _Tp, typename = decltype(_Tp())>
26 static boost::type_traits::yes_type test(int);
27
28 template<typename>
29 static boost::type_traits::no_type test(...);
30 };
31
32 }
33
34 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)>{};
35 template <class T, std::size_t N> struct is_default_constructible<T[N]> : public is_default_constructible<T>{};
36 template <class T> struct is_default_constructible<T[]> : public is_default_constructible<T>{};
37 template <class T> struct is_default_constructible<T&> : public integral_constant<bool, false>{};
38#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
39 template <class T> struct is_default_constructible<T&&> : public integral_constant<bool, false>{};
40#endif
41 template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
42 template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
43 template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
44 template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
45
46#else
47
48#include <boost/type_traits/is_pod.hpp>
49
50namespace boost{
51
52 // We don't know how to implement this, note we can not use has_trivial_constructor here
53 // because the correct implementation of that trait requires this one:
54 template <class T> struct is_default_constructible : public is_pod<T>{};
55 template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
56 template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
57 template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
58 template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
59
60#endif
61
62} // namespace boost
63
64#endif // BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
65