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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 |