[cmp.strongord] (original) (raw)

17 Language support library [support]

17.11 Comparisons [cmp]

17.11.2 Comparison category types [cmp.categories]

17.11.2.4 Class strong_­ordering [cmp.strongord]

The strong_­ordering type is typically used as the result type of a three-way comparison operatorthat (a) admits all of the six two-way comparison operators ([expr.rel], [expr.eq]), and (b) does imply substitutability.

namespace std { class strong_ordering { int value;

constexpr explicit strong_ordering(eq v) noexcept : value(int(v)) {}    
constexpr explicit strong_ordering(ord v) noexcept : value(int(v)) {}   

public:

static const strong_ordering less;
static const strong_ordering equal;
static const strong_ordering equivalent;
static const strong_ordering greater;


constexpr operator partial_ordering() const noexcept;
constexpr operator weak_ordering() const noexcept;


friend constexpr bool operator==(strong_ordering v, unspecified) noexcept;
friend constexpr bool operator==(strong_ordering v, strong_ordering w) noexcept = default;
friend constexpr bool operator< (strong_ordering v, unspecified) noexcept;
friend constexpr bool operator> (strong_ordering v, unspecified) noexcept;
friend constexpr bool operator<=(strong_ordering v, unspecified) noexcept;
friend constexpr bool operator>=(strong_ordering v, unspecified) noexcept;
friend constexpr bool operator< (unspecified, strong_ordering v) noexcept;
friend constexpr bool operator> (unspecified, strong_ordering v) noexcept;
friend constexpr bool operator<=(unspecified, strong_ordering v) noexcept;
friend constexpr bool operator>=(unspecified, strong_ordering v) noexcept;
friend constexpr strong_ordering operator<=>(strong_ordering v, unspecified) noexcept;
friend constexpr strong_ordering operator<=>(unspecified, strong_ordering v) noexcept;

};

inline constexpr strong_ordering strong_ordering::less(ord::less); inline constexpr strong_ordering strong_ordering::equal(eq::equal); inline constexpr strong_ordering strong_ordering::equivalent(eq::equivalent); inline constexpr strong_ordering strong_ordering::greater(ord::greater); }

constexpr operator partial_ordering() const noexcept;

Returns:

value == 0 ? partial_ordering::equivalent : value < 0 ? partial_ordering::less : partial_ordering::greater

constexpr operator weak_ordering() const noexcept;

Returns:

value == 0 ? weak_ordering::equivalent : value < 0 ? weak_ordering::less : weak_ordering::greater

constexpr bool operator==(strong_ordering v, unspecified) noexcept;constexpr bool operator< (strong_ordering v, unspecified) noexcept;constexpr bool operator> (strong_ordering v, unspecified) noexcept;constexpr bool operator<=(strong_ordering v, unspecified) noexcept;constexpr bool operator>=(strong_ordering v, unspecified) noexcept;

Returns: v.value @ 0 for operator@.

constexpr bool operator< (unspecified, strong_ordering v) noexcept;constexpr bool operator> (unspecified, strong_ordering v) noexcept;constexpr bool operator<=(unspecified, strong_ordering v) noexcept;constexpr bool operator>=(unspecified, strong_ordering v) noexcept;

Returns: 0 @ v.value for operator@.

constexpr strong_ordering operator<=>(strong_ordering v, unspecified) noexcept;

constexpr strong_ordering operator<=>(unspecified, strong_ordering v) noexcept;

Returns: v < 0 ? strong_­ordering​::​greater : v > 0 ? strong_­ordering​::​less : v.