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 <cstddef> // size_t
13#include <boost/type_traits/integral_constant.hpp>
14#include <boost/detail/workaround.hpp>
15
16#if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
17#include <boost/type_traits/is_abstract.hpp>
18#endif
19
20#if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
21
22#include <boost/type_traits/detail/yes_no_type.hpp>
23
24namespace boost{
25
26 namespace detail{
27
28 struct is_default_constructible_imp
29 {
30 template<typename _Tp, typename = decltype(_Tp())>
31 static boost::type_traits::yes_type test(int);
32
33 template<typename>
34 static boost::type_traits::no_type test(...);
35 };
36#if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
37 template<class T, bool b>
38 struct is_default_constructible_abstract_filter
39 {
40 static const bool value = sizeof(is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type);
41 };
42 template<class T>
43 struct is_default_constructible_abstract_filter<T, true>
44 {
45 static const bool value = false;
46 };
47#endif
48 }
49
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>{};
52#else
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)>{};
54#endif
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>{};
60#endif
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>{};
65
66#else
67
68#include <boost/type_traits/is_pod.hpp>
69
70namespace boost{
71
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>{};
79
80#endif
81
82} // namespace boost
83
84#endif // BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
85