alloc.hpp

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#ifndef ZEN_ALLOC_HPP
#define ZEN_ALLOC_HPP
 
#include <concepts>
#include <new>
#include <utility>
 
#include "zen/config.hpp"
 
ZEN_NAMESPACE_START

using destroy_fn = void (*)(void *);

template<typename T>
concept DynamicAllocator = requires (
  T& t,
  std::size_t size,
  std::size_t alignment,
  destroy_fn destroy
) {
  { t.allocate(size, alignment, destroy) } -> std::same_as<void*>;
};

template<typename R, DynamicAllocator Alloc, typename ...Ts>
R* construct(Alloc& allocator, Ts&& ...args) {
  auto ptr = allocator.allocate(
    sizeof(R),
    alignof(R),
    [](void* ptr) { static_cast<R*>(ptr)->~R(); }
  );
  if (ZEN_UNLIKELY(!ptr)) {
    return nullptr;
  }
  ::new (ptr) R (std::forward<Ts>(args)...);
  return std::launder(reinterpret_cast<R*>(ptr));
}
 
ZEN_NAMESPACE_END
 
#endif // of #ifndef ZEN_ALLOC_HPP