Difference between revisions of "cpp/header/compare"
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{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc h1 | Concepts}} | + | {{dsc h1|Concepts}} |
| − | {{dsc inc | cpp/utility/compare/dsc three_way_comparable}} | + | {{dsc inc|cpp/utility/compare/dsc three_way_comparable}} |
| − | {{dsc h1 | Classes}} | + | {{dsc h1|Classes}} |
| − | {{dsc inc | cpp/utility/compare/dsc partial_ordering}} | + | {{dsc inc|cpp/utility/compare/dsc partial_ordering}} |
| − | {{dsc inc | cpp/utility/compare/dsc weak_ordering}} | + | {{dsc inc|cpp/utility/compare/dsc weak_ordering}} |
| − | {{dsc inc | cpp/utility/compare/dsc strong_ordering}} | + | {{dsc inc|cpp/utility/compare/dsc strong_ordering}} |
| − | {{dsc inc | cpp/utility/compare/dsc common_comparison_category}} | + | {{dsc inc|cpp/utility/compare/dsc common_comparison_category}} |
| − | {{dsc inc | cpp/utility/compare/dsc compare_three_way_result}} | + | {{dsc inc|cpp/utility/compare/dsc compare_three_way_result}} |
| − | {{dsc inc | cpp/utility/compare/dsc compare_three_way}} | + | {{dsc inc|cpp/utility/compare/dsc compare_three_way}} |
| − | {{dsc h1 | Customization point objects}} | + | {{dsc h1|Customization point objects}} |
| − | {{dsc inc | cpp/utility/compare/dsc strong_order}} | + | {{dsc inc|cpp/utility/compare/dsc strong_order}} |
| − | {{dsc inc | cpp/utility/compare/dsc weak_order}} | + | {{dsc inc|cpp/utility/compare/dsc weak_order}} |
| − | {{dsc inc | cpp/utility/compare/dsc partial_order}} | + | {{dsc inc|cpp/utility/compare/dsc partial_order}} |
| − | {{dsc inc | cpp/utility/compare/dsc compare_strong_order_fallback}} | + | {{dsc inc|cpp/utility/compare/dsc compare_strong_order_fallback}} |
| − | {{dsc inc | cpp/utility/compare/dsc compare_weak_order_fallback}} | + | {{dsc inc|cpp/utility/compare/dsc compare_weak_order_fallback}} |
| − | {{dsc inc | cpp/utility/compare/dsc compare_partial_order_fallback}} | + | {{dsc inc|cpp/utility/compare/dsc compare_partial_order_fallback}} |
| − | {{dsc h1 | Functions}} | + | {{dsc h1|Functions}} |
| − | {{dsc inc | cpp/utility/compare/dsc named_comparison_functions}} | + | {{dsc inc|cpp/utility/compare/dsc named_comparison_functions}} |
{{dsc end}} | {{dsc end}} | ||
===Synopsis=== | ===Synopsis=== | ||
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===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc | + | {{dsc|[[cpp/language/operator comparison#Three-way comparison|'''three-way comparison operator''']] expression ''lhs'' {{ttb|1= <=>}} ''rhs'' {{mark c++20}}}} |
{{dsc end}} | {{dsc end}} | ||
| − | {{langlinks|es|ja|zh}} | + | {{langlinks|de|es|ja|ru|zh}} |
Latest revision as of 03:26, 7 January 2024
This header is part of the language support library.
Concepts | ||
| specifies that operator <=> produces consistent result on given types (concept) | ||
Classes | ||
| (C++20) |
the result type of 3-way comparison that supports all 6 operators, is not substitutable, and allows incomparable values (class) | |
| (C++20) |
the result type of 3-way comparison that supports all 6 operators and is not substitutable (class) | |
| (C++20) |
the result type of 3-way comparison that supports all 6 operators and is substitutable (class) | |
| (C++20) |
the strongest comparison category to which all of the given types can be converted (class template) | |
| (C++20) |
obtains the result type of the three-way comparison operator <=> on given types (class template) | |
| (C++20) |
constrained function object implementing x <=> y (class) | |
Customization point objects | ||
| (C++20) |
performs 3-way comparison and produces a result of type std::strong_ordering(customization point object) | |
| (C++20) |
performs 3-way comparison and produces a result of type std::weak_ordering(customization point object) | |
| (C++20) |
performs 3-way comparison and produces a result of type std::partial_ordering(customization point object) | |
performs 3-way comparison and produces a result of type std::strong_ordering, even if operator<=> is unavailable(customization point object) | ||
| (C++20) |
performs 3-way comparison and produces a result of type std::weak_ordering, even if operator<=> is unavailable(customization point object) | |
performs 3-way comparison and produces a result of type std::partial_ordering, even if operator<=> is unavailable(customization point object) | ||
Functions | ||
| named comparison functions (function) | ||
[edit] Synopsis
namespace std { // comparison category types class partial_ordering; class weak_ordering; class strong_ordering; // named comparison functions 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; } // common comparison category type template<class... Ts> struct common_comparison_category { using type = /* see description */; }; template<class... Ts> using common_comparison_category_t = typename common_comparison_category<Ts...>::type; // concept three_way_comparable template<class T, class Cat = partial_ordering> concept three_way_comparable = /* see description */; template<class T, class U, class Cat = partial_ordering> concept three_way_comparable_with = /* see description */; // result of three-way comparison 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; // class compare_three_way struct compare_three_way; // comparison algorithms 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 */; } }
[edit] Concept three_way_comparable
namespace std { template<class T, class Cat> concept __ComparesAs = // exposition only same_as<common_comparison_category_t<T, Cat>, Cat>; template<class T, class U> concept __PartiallyOrderedWith = // exposition only requires(const remove_reference_t<T>& t, const remove_reference_t<U>& u) { { t < u } -> boolean-testable; { t > u } -> boolean-testable; { t <= u } -> boolean-testable; { t >= u } -> boolean-testable; { u < t } -> boolean-testable; { u > t } -> boolean-testable; { u <= t } -> boolean-testable; { u >= t } -> boolean-testable; }; template<class T, class Cat = partial_ordering> concept three_way_comparable = __WeaklyEqualityComparableWith<T, T> && __PartiallyOrderedWith<T, T> && requires(const remove_reference_t<T>& a, const remove_reference_t<T>& b) { { a <=> b } -> __ComparesAs<Cat>; }; }
[edit] Concept three_way_comparable_with
namespace std { template<class T, class U, class Cat = partial_ordering> concept three_way_comparable_with = __WeaklyEqualityComparableWith<T, U> && __PartiallyOrderedWith<T, U> && three_way_comparable<T, Cat> && three_way_comparable<U, Cat> && common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&> && three_way_comparable< common_reference_t< const remove_reference_t<T>&, const remove_reference_t<U>&>, Cat> && requires(const remove_reference_t<T>& t, const remove_reference_t<U>& u) { { t <=> u } -> __ComparesAs<Cat>; { u <=> t } -> __ComparesAs<Cat>; }; }
[edit] Class std::partial_ordering
namespace std { class partial_ordering { int value; // exposition only bool is_ordered; // exposition only // exposition-only constructors constexpr explicit partial_ordering(eq v) noexcept : value(int(v)), is_ordered(true) {} // exposition only constexpr explicit partial_ordering(ord v) noexcept : value(int(v)), is_ordered(true) {} // exposition only constexpr explicit 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; // comparisons friend constexpr bool operator==(partial_ordering v, /* unspecified */) noexcept; friend constexpr bool operator==(partial_ordering v, partial_ordering w) noexcept = default; 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 partial_ordering operator<=>(partial_ordering v, /* unspecified */) noexcept; friend constexpr partial_ordering 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); }
[edit] Class std::weak_ordering
namespace std { class weak_ordering { int value; // exposition only // exposition-only constructors constexpr explicit weak_ordering(eq v) noexcept : value(int(v)) {} // exposition only constexpr explicit 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 partial_ordering() const noexcept; // comparisons friend constexpr bool operator==(weak_ordering v, /* unspecified */) noexcept; friend constexpr bool operator==(weak_ordering v, weak_ordering w) noexcept = default; 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 weak_ordering operator<=>(weak_ordering v, /* unspecified */) noexcept; friend constexpr weak_ordering 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); }
[edit] Class std::strong_ordering
namespace std { class strong_ordering { int value; // exposition only // exposition-only constructors constexpr explicit strong_ordering(eq v) noexcept : value(int(v)) {} // exposition only constexpr explicit 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 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, 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; }; // 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); }
[edit] Class std::compare_three_way
namespace std { struct compare_three_way { template<class T, class U> constexpr auto operator()(T&& t, U&& u) const; using is_transparent = /* unspecified */; }; }
[edit] See also
three-way comparison operator expression lhs <=> rhs (C++20)
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