This header is part of the general utility library.
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(C++20) | the result type of 3-way comparison that supports only equality/inequality and is not substitutable (class) |
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(C++20) | the result type of 3-way comparison that supports only equality/inequality and is substitutable (class) |
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(C++20) | the result type of 3-way comparison that supports all 6 operators, is not substitutable, and allows incomparable values (class) |
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(C++20) | the result type of 3-way comparison that supports all 6 operators and is not substitutable (class) |
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(C++20) | the result type of 3-way comparison that supports all 6 operators and is substitutable (class) |
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(C++20) | the strongest comparison category to which all of the given types can be converted (class template) |
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(C++20) | named comparison functions (function) |
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(C++20) | performs 3-way comparison and produces a result of type std::strong_ordering (function template) |
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(C++20) | performs 3-way comparison and produces a result of type std::weak_ordering (function template) |
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(C++20) | performs 3-way comparison and produces a result of type std::partial_ordering (function template) |
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(C++20) | performs 3-way comparison and produces a result of type std::strong_equality (function template) |
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(C++20) | performs 3-way comparison and produces a result of type std::weak_equality (function template) |
namespace std {
// comparison category types
class weak_equality;
class strong_equality;
class partial_ordering;
class weak_ordering;
class strong_ordering;
// named comparison functions
constexpr bool is_eq (weak_equality cmp) noexcept { return cmp == 0; }
constexpr bool is_neq (weak_equality 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; }
// common comparison category type
template<class... Ts>
struct common_comparison_category {
using type = /* see definition */ ;
};
template<class... Ts>
using common_comparison_category_t = typename common_comparison_category<Ts...>::type;
// comparison algorithms
template<class T> constexpr strong_ordering strong_order(const T& a, const T& b);
template<class T> constexpr weak_ordering weak_order(const T& a, const T& b);
template<class T> constexpr partial_ordering partial_order(const T& a, const T& b);
template<class T> constexpr strong_equality strong_equal(const T& a, const T& b);
template<class T> constexpr weak_equality weak_equal(const T& a, const T& b);
}std::weak_equality
namespace std {
class weak_equality {
int value; // exposition only
// exposition-only constructor
explicit constexpr weak_equality(eq v) noexcept : value(int(v)) {} // exposition only
public:
// valid values
static const weak_equality equivalent;
static const weak_equality nonequivalent;
// comparisons
friend constexpr bool operator==(weak_equality v, /*unspecified*/ ) noexcept;
friend constexpr bool operator!=(weak_equality v, /*unspecified*/ ) noexcept;
friend constexpr bool operator==(/*unspecified*/ , weak_equality v) noexcept;
friend constexpr bool operator!=(/*unspecified*/ , weak_equality v) noexcept;
};
// valid values’ definitions
inline constexpr weak_equality weak_equality::equivalent(eq::equivalent);
inline constexpr weak_equality weak_equality::nonequivalent(eq::nonequivalent);
}std::strong_equality
namespace std {
class strong_equality {
int value; // exposition only
// exposition-only constructor
explicit constexpr strong_equality(eq v) noexcept : value(int(v)) {} // exposition only
public:
// valid values
static const strong_equality equal;
static const strong_equality nonequal;
static const strong_equality equivalent;
static const strong_equality nonequivalent;
// conversion
constexpr operator weak_equality() const noexcept;
// comparisons
friend constexpr bool operator==(strong_equality v, /*unspecified*/ ) noexcept;
friend constexpr bool operator!=(strong_equality v, /*unspecified*/ ) noexcept;
friend constexpr bool operator==(/*unspecified*/ , strong_equality v) noexcept;
friend constexpr bool operator!=(/*unspecified*/ , strong_equality v) noexcept;
};
// valid values’ definitions
inline constexpr strong_equality strong_equality::equal(eq::equal);
inline constexpr strong_equality strong_equality::nonequal(eq::nonequal);
inline constexpr strong_equality strong_equality::equivalent(eq::equivalent);
inline constexpr strong_equality strong_equality::nonequivalent(eq::nonequivalent);
}std::partial_ordering
namespace std {
class partial_ordering {
int value; // exposition only
bool is_ordered; // exposition only
// exposition-only constructors
explicit constexpr
partial_ordering(eq v) noexcept : value(int(v)), is_ordered(true) {} // exposition only
explicit constexpr
partial_ordering(ord v) noexcept : value(int(v)), is_ordered(true) {} // exposition only
explicit constexpr
partial_ordering(ncmp v) noexcept : value(int(v)), is_ordered(false) {} // exposition only
public:
// valid values
static const partial_ordering less;
static const partial_ordering equivalent;
static const partial_ordering greater;
static const partial_ordering unordered;
// conversion
constexpr operator weak_equality() const noexcept;
// comparisons
friend constexpr bool operator==(partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator!=(partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator< (partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator<=(partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator> (partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator>=(partial_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator==(/*unspecified*/ , partial_ordering v) noexcept;
friend constexpr bool operator!=(/*unspecified*/ , partial_ordering v) noexcept;
friend constexpr bool operator< (/*unspecified*/ , partial_ordering v) noexcept;
friend constexpr bool operator<=(/*unspecified*/ , partial_ordering v) noexcept;
friend constexpr bool operator> (/*unspecified*/ , partial_ordering v) noexcept;
friend constexpr bool operator>=(/*unspecified*/ , partial_ordering v) noexcept;
};
// valid values’ definitions
inline constexpr partial_ordering partial_ordering::less(ord::less);
inline constexpr partial_ordering partial_ordering::equivalent(eq::equivalent);
inline constexpr partial_ordering partial_ordering::greater(ord::greater);
inline constexpr partial_ordering partial_ordering::unordered(ncmp::unordered);
}std::weak_ordering
namespace std {
class weak_ordering {
int value; // exposition only
// exposition-only constructors
explicit constexpr weak_ordering(eq v) noexcept : value(int(v)) {} // exposition only
explicit constexpr weak_ordering(ord v) noexcept : value(int(v)) {} // exposition only
public:
// valid values
static const weak_ordering less;
static const weak_ordering equivalent;
static const weak_ordering greater;
// conversions
constexpr operator weak_equality() const noexcept;
constexpr operator partial_ordering() const noexcept;
// comparisons
friend constexpr bool operator==(weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator!=(weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator< (weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator<=(weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator> (weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator>=(weak_ordering v, /*unspecified*/ ) noexcept;
friend constexpr bool operator==(/*unspecified*/ , weak_ordering v) noexcept;
friend constexpr bool operator!=(/*unspecified*/ , weak_ordering v) noexcept;
friend constexpr bool operator< (/*unspecified*/ , weak_ordering v) noexcept;
friend constexpr bool operator<=(/*unspecified*/ , weak_ordering v) noexcept;
friend constexpr bool operator> (/*unspecified*/ , weak_ordering v) noexcept;
friend constexpr bool operator>=(/*unspecified*/ , weak_ordering v) noexcept;
};
// valid values’ definitions
inline constexpr weak_ordering weak_ordering::less(ord::less);
inline constexpr weak_ordering weak_ordering::equivalent(eq::equivalent);
inline constexpr weak_ordering weak_ordering::greater(ord::greater);
}std::strong_ordering
namespace std {
class strong_ordering {
int value; // exposition only
// exposition-only constructors
explicit constexpr strong_ordering(eq v) noexcept : value(int(v)) {} // exposition only
explicit constexpr strong_ordering(ord v) noexcept : value(int(v)) {} // exposition only
public:
// valid values
static const strong_ordering less;
static const strong_ordering equal;
static const strong_ordering equivalent;
static const strong_ordering greater;
// conversions
constexpr operator weak_equality() const noexcept;
constexpr operator strong_equality() const noexcept;
constexpr operator partial_ordering() const noexcept;
constexpr operator weak_ordering() const noexcept;
// comparisons
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> (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 bool operator> (/*unspecified*/ , strong_ordering v) noexcept;
friend constexpr bool operator>=(/*unspecified*/ , strong_ordering v) noexcept;
};
// valid values’ definitions
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);
} C++ documentation for three-way comparison operator (C++20) |
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