compat.hpp

#ifndef ZEN_COMPAT_HPP
#define ZEN_COMPAT_HPP
 
#include <iterator>
 
#include "zen/config.hpp"
 
ZEN_NAMESPACE_START

template<std::indirectly_readable T>
using iter_const_reference_t = std::common_reference_t<
  const std::iter_value_t<T>&&,
  std::iter_reference_t<T>
>;
 
template<typename T, typename ... U>
concept neither = (!std::same_as<T, U> && ...);
 
template<typename T>
concept strict_unsigned_integral = std::unsigned_integral<T> &&
  neither<T, bool, char, char8_t, char16_t, char32_t, wchar_t>;

constexpr bool has_single_bit(strict_unsigned_integral auto x) noexcept {
  return x && !(x & (x - 1));
}
 
ZEN_NAMESPACE_END
 
#endif // of #ifndef ZEN_COMPAT_HPP