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_CONSTRUCTIBLE_HPP_INCLUDED |
10 | #define BOOST_TT_IS_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_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500) |
16 | |
17 | #include <boost/type_traits/is_destructible.hpp> |
18 | #include <boost/type_traits/is_default_constructible.hpp> |
19 | #include <boost/type_traits/detail/yes_no_type.hpp> |
20 | #include <boost/type_traits/declval.hpp> |
21 | |
22 | namespace boost{ |
23 | |
24 | namespace detail{ |
25 | |
26 | struct is_constructible_imp |
27 | { |
28 | template<typename T, typename ...TheArgs, typename = decltype(T(boost::declval<TheArgs>()...))> |
29 | static boost::type_traits::yes_type test(int); |
30 | template<typename, typename...> |
31 | static boost::type_traits::no_type test(...); |
32 | |
33 | template<typename T, typename Arg, typename = decltype(::new T(boost::declval<Arg>()))> |
34 | static boost::type_traits::yes_type test1(int); |
35 | template<typename, typename> |
36 | static boost::type_traits::no_type test1(...); |
37 | |
38 | template <typename T> |
39 | static boost::type_traits::yes_type ref_test(T); |
40 | template <typename T> |
41 | static boost::type_traits::no_type ref_test(...); |
42 | }; |
43 | |
44 | } |
45 | |
46 | template <class T, class ...Args> struct is_constructible : public integral_constant<bool, sizeof(detail::is_constructible_imp::test<T, Args...>(0)) == sizeof(boost::type_traits::yes_type)>{}; |
47 | template <class T, class Arg> struct is_constructible<T, Arg> : public integral_constant<bool, is_destructible<T>::value && sizeof(detail::is_constructible_imp::test1<T, Arg>(0)) == sizeof(boost::type_traits::yes_type)>{}; |
48 | template <class Ref, class Arg> struct is_constructible<Ref&, Arg> : public integral_constant<bool, sizeof(detail::is_constructible_imp::ref_test<Ref&>(boost::declval<Arg>())) == sizeof(boost::type_traits::yes_type)>{}; |
49 | template <class Ref, class Arg> struct is_constructible<Ref&&, Arg> : public integral_constant<bool, sizeof(detail::is_constructible_imp::ref_test<Ref&&>(boost::declval<Arg>())) == sizeof(boost::type_traits::yes_type)>{}; |
50 | |
51 | template <> struct is_constructible<void> : public false_type{}; |
52 | template <> struct is_constructible<void const> : public false_type{}; |
53 | template <> struct is_constructible<void const volatile> : public false_type{}; |
54 | template <> struct is_constructible<void volatile> : public false_type{}; |
55 | |
56 | template <class T> struct is_constructible<T> : public is_default_constructible<T>{}; |
57 | |
58 | #else |
59 | |
60 | #include <boost/type_traits/is_convertible.hpp> |
61 | #include <boost/type_traits/is_default_constructible.hpp> |
62 | |
63 | namespace boost{ |
64 | |
65 | // We don't know how to implement this: |
66 | template <class T, class U = void> struct is_constructible : public is_convertible<U, T>{}; |
67 | template <class T> struct is_constructible<T, void> : public is_default_constructible<T>{}; |
68 | template <> struct is_constructible<void, void> : public false_type{}; |
69 | template <> struct is_constructible<void const, void> : public false_type{}; |
70 | template <> struct is_constructible<void const volatile, void> : public false_type{}; |
71 | template <> struct is_constructible<void volatile, void> : public false_type{}; |
72 | template <class Ref> struct is_constructible<Ref&, void> : public false_type{}; |
73 | #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES |
74 | template <class Ref> struct is_constructible<Ref&&, void> : public false_type{}; |
75 | #endif |
76 | #endif |
77 | |
78 | } // namespace boost |
79 | |
80 | #endif // BOOST_TT_IS_CONSTRUCTIBLE_HPP_INCLUDED |
81 | |