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Move is_swappable implementation, correct MSC_VER check

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This commit is contained in:
Simon Brand
2019-02-19 14:58:09 +00:00
parent 7ef0154330
commit d2c6fa68c7
1 changed files with 73 additions and 73 deletions
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146
tl/optional.hpp
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@ -204,6 +204,79 @@ using invoke_result = invoke_result_impl<F, void, Us...>;
template <class F, class... Us>
using invoke_result_t = typename invoke_result<F, Us...>::type;
#if defined(_MSC_VER) && _MSC_VER <= 1900
// TODO make a version which works with MSVC 2015
template <class T, class U = T> struct is_swappable : std::true_type {};
template <class T, class U = T> struct is_nothrow_swappable : std::true_type {};
#else
// https://stackoverflow.com/questions/26744589/what-is-a-proper-way-to-implement-is-swappable-to-test-for-the-swappable-concept
namespace swap_adl_tests {
// if swap ADL finds this then it would call std::swap otherwise (same
// signature)
struct tag {};
template <class T> tag swap(T &, T &);
template <class T, std::size_t N> tag swap(T (&a)[N], T (&b)[N]);
// helper functions to test if an unqualified swap is possible, and if it
// becomes std::swap
template <class, class> std::false_type can_swap(...) noexcept(false);
template <class T, class U,
class = decltype(swap(std::declval<T &>(), std::declval<U &>()))>
std::true_type can_swap(int) noexcept(noexcept(swap(std::declval<T &>(),
std::declval<U &>())));
template <class, class> std::false_type uses_std(...);
template <class T, class U>
std::is_same<decltype(swap(std::declval<T &>(), std::declval<U &>())), tag>
uses_std(int);
template <class T>
struct is_std_swap_noexcept
: std::integral_constant<bool,
std::is_nothrow_move_constructible<T>::value &&
std::is_nothrow_move_assignable<T>::value> {};
template <class T, std::size_t N>
struct is_std_swap_noexcept<T[N]> : is_std_swap_noexcept<T> {};
template <class T, class U>
struct is_adl_swap_noexcept
: std::integral_constant<bool, noexcept(can_swap<T, U>(0))> {};
} // namespace swap_adl_tests
template <class T, class U = T>
struct is_swappable
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap<T, U>(0))::value &&
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value ||
(std::is_move_assignable<T>::value &&
std::is_move_constructible<T>::value))> {};
template <class T, std::size_t N>
struct is_swappable<T[N], T[N]>
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap<T[N], T[N]>(0))::value &&
(!decltype(
detail::swap_adl_tests::uses_std<T[N], T[N]>(0))::value ||
is_swappable<T, T>::value)> {};
template <class T, class U = T>
struct is_nothrow_swappable
: std::integral_constant<
bool,
is_swappable<T, U>::value &&
((decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value
&&detail::swap_adl_tests::is_std_swap_noexcept<T>::value) ||
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value &&
detail::swap_adl_tests::is_adl_swap_noexcept<T,
U>::value))> {
};
#endif
#endif
// std::void_t from C++17
@ -278,79 +351,6 @@ using enable_assign_from_other = detail::enable_if_t<
!std::is_assignable<T &, const optional<U> &>::value &&
!std::is_assignable<T &, const optional<U> &&>::value>;
#if defined(_MSC_VER) && _MSC_VER < 1900
// TODO make a version which works with MSVC 2015
template <class T, class U = T> struct is_swappable : std::true_type {};
template <class T, class U = T> struct is_nothrow_swappable : std::true_type {};
#else
// https://stackoverflow.com/questions/26744589/what-is-a-proper-way-to-implement-is-swappable-to-test-for-the-swappable-concept
namespace swap_adl_tests {
// if swap ADL finds this then it would call std::swap otherwise (same
// signature)
struct tag {};
template <class T> tag swap(T &, T &);
template <class T, std::size_t N> tag swap(T (&a)[N], T (&b)[N]);
// helper functions to test if an unqualified swap is possible, and if it
// becomes std::swap
template <class, class> std::false_type can_swap(...) noexcept(false);
template <class T, class U,
class = decltype(swap(std::declval<T &>(), std::declval<U &>()))>
std::true_type can_swap(int) noexcept(noexcept(swap(std::declval<T &>(),
std::declval<U &>())));
template <class, class> std::false_type uses_std(...);
template <class T, class U>
std::is_same<decltype(swap(std::declval<T &>(), std::declval<U &>())), tag>
uses_std(int);
template <class T>
struct is_std_swap_noexcept
: std::integral_constant<bool,
std::is_nothrow_move_constructible<T>::value &&
std::is_nothrow_move_assignable<T>::value> {};
template <class T, std::size_t N>
struct is_std_swap_noexcept<T[N]> : is_std_swap_noexcept<T> {};
template <class T, class U>
struct is_adl_swap_noexcept
: std::integral_constant<bool, noexcept(can_swap<T, U>(0))> {};
} // namespace swap_adl_tests
template <class T, class U = T>
struct is_swappable
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap<T, U>(0))::value &&
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value ||
(std::is_move_assignable<T>::value &&
std::is_move_constructible<T>::value))> {};
template <class T, std::size_t N>
struct is_swappable<T[N], T[N]>
: std::integral_constant<
bool,
decltype(detail::swap_adl_tests::can_swap<T[N], T[N]>(0))::value &&
(!decltype(
detail::swap_adl_tests::uses_std<T[N], T[N]>(0))::value ||
is_swappable<T, T>::value)> {};
template <class T, class U = T>
struct is_nothrow_swappable
: std::integral_constant<
bool,
is_swappable<T, U>::value &&
((decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value
&&detail::swap_adl_tests::is_std_swap_noexcept<T>::value) ||
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value &&
detail::swap_adl_tests::is_adl_swap_noexcept<T,
U>::value))> {
};
#endif
// The storage base manages the actual storage, and correctly propagates
// trivial destruction from T. This case is for when T is not trivially
// destructible.