17 Language support library [support] (original) (raw)

The header <compare> specifies types, objects, and functions for use primarily in connection with the three-way comparison operator.

namespace std {

class partial_ordering; class weak_ordering; class strong_ordering;

constexpr bool is_eq (partial_ordering cmp) noexcept { return cmp == 0; } constexpr bool is_neq (partial_ordering cmp) noexcept { return cmp != 0; } constexpr bool is_lt (partial_ordering cmp) noexcept { return cmp < 0; } constexpr bool is_lteq(partial_ordering cmp) noexcept { return cmp <= 0; } constexpr bool is_gt (partial_ordering cmp) noexcept { return cmp > 0; } constexpr bool is_gteq(partial_ordering cmp) noexcept { return cmp >= 0; }

template<class... Ts> struct common_comparison_category { using type = see below; }; template<class... Ts> using common_comparison_category_t = typename common_comparison_category<Ts...>::type;

template<class T, class Cat = partial_ordering> concept three_way_comparable = see below; template<class T, class U, class Cat = partial_ordering> concept three_way_comparable_with = see below;

template<class T, class U = T> struct compare_three_way_result;

template<class T, class U = T> using compare_three_way_result_t = typename compare_three_way_result<T, U>::type;

struct compare_three_way;

inline namespace unspecified { inline constexpr unspecified strong_order = unspecified; inline constexpr unspecified weak_order = unspecified; inline constexpr unspecified partial_order = unspecified; inline constexpr unspecified compare_strong_order_fallback = unspecified; inline constexpr unspecified compare_weak_order_fallback = unspecified; inline constexpr unspecified compare_partial_order_fallback = unspecified; } }