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 | |
24 | namespace 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 | |
70 | namespace 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 | |