meta::equality_comparable_with¶

Defined in header <mgs/meta/concepts/equality_comparable_with.hpp>.

template <typename T, typename U>
concept equality_comparable_with =
  meta::equality_comparable<T> &&
  meta::equality_comparable<U> &&
  meta::common_reference_with<
    std::remove_reference_t<T> const&,
    std::remove_reference_t<U> const&> &&
  meta::equality_comparable<
    meta::common_reference_t<
      std::remove_reference_t<T> const&,
      std::remove_reference_t<U> const&>> &&
  meta::weakly_equality_comparable_with<T, U>;

Pre-C++20 implementation of the std::equality_comparable_with concept.

Concept emulation¶

namespace mgs {
namespace meta {

template <typename T, typename U>
struct is_equality_comparable_with { /* ... */ };

template <typename T, typename U>
constexpr auto is_equality_comparable_with_v =
                  is_equality_comparable_with<T, U>::value;

template <typename T, typename U,
          typename = std::enable_if_t<is_equality_comparable_v<T, U>>>
using equality_comparable_with = T;

} // namespace meta
} // namespace mgs

Example¶

#include <mgs/meta/concepts/equality_comparable_with.hpp>

using namespace mgs::meta;

static_assert(is_equality_comparable_with_v<int, float>, "");
static_assert(!is_equality_comparable_with_v<std::mutex, int>, "");

See also¶