std::common_comparison_category

template<class... Ts>
struct common_comparison_category {
  using type = /*see below*/ ;
};

The class template std::common_comparison_category provides an alias (as the member typedef type) for the strongest comparison category to which all of the template arguments Ts... can be converted.

In detail, the common comparison type of a list of n types T0...Tn-1 is defined as follows:

• If any Ti is not a comparison category type (std::weak_equality, std::strong_equality, std::partial_ordering, std::weak_ordering, std::strong_ordering), U is void.
• Otherwise, if at least one Ti is std::weak_equality or at least one Ti is std::strong_equality and at least one Ti is std::partial_ordering or std::weak_ordering, U is std::weak_equality
• Otherwise, if at least one Ti is std::strong_equality, U is std::strong_equality
• Otherwise, (if there is no std::weak_equality and no std::strong_equality) if at least one Ti is std::partial_ordering, U is std::partial_ordering
• Otherwise, if at least one Ti is std::weak_ordering, U is std::weak_ordering
• Otherwise (if every Ti is std::strong_ordering, or if the list is empty), U is std::strong_ordering.

Template parameters

Helper template

template< class... Ts >
using common_comparison_category_t = typename common_comparison_category<Ts...>::type;

Member types

Example

See also