Viewing file:  construct_at.h (1.58 KB) -rw-r--r--
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// A minimal conforming implementation of std::construct_at/destroy_at,
// used by some C++20 constexpr tests to avoid including all of <memory>.
namespace std
{
typedef __SIZE_TYPE__ size_t;
template <typename T>
struct allocator
{
constexpr allocator () noexcept {}
constexpr T *allocate (size_t n)
{ return static_cast<T *> (::operator new (n * sizeof(T))); }
constexpr void
deallocate (T *p, size_t n)
{ ::operator delete (p); }
};
template <typename T, typename U = T &&>
U __declval (int);
template <typename T>
T __declval (long);
template <typename T>
auto declval () noexcept -> decltype (__declval<T> (0));
template <typename T>
struct remove_reference
{ typedef T type; };
template <typename T>
struct remove_reference<T &>
{ typedef T type; };
template <typename T>
struct remove_reference<T &&>
{ typedef T type; };
template <typename T>
constexpr T &&
forward (typename std::remove_reference<T>::type &t) noexcept
{ return static_cast<T&&> (t); }
template<typename T>
constexpr T &&
forward (typename std::remove_reference<T>::type &&t) noexcept
{ return static_cast<T&&> (t); }
template <typename T, typename... A>
constexpr auto
construct_at (T *l, A &&... a)
noexcept (noexcept (::new ((void *) 0) T (std::declval<A> ()...)))
-> decltype (::new ((void *) 0) T (std::declval<A> ()...))
{ return ::new ((void *) l) T (std::forward<A> (a)...); }
template <typename T>
constexpr inline void
destroy_at (T *l)
{ l->~T (); }
}
inline void *operator new (std::size_t, void *p) noexcept
{ return p; }
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