97 lines
4.9 KiB
Markdown
97 lines
4.9 KiB
Markdown
[cmp.strongord]
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# 17 Language support library [[support]](./#support)
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## 17.12 Comparisons [[cmp]](cmp#strongord)
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### 17.12.2 Comparison category types [[cmp.categories]](cmp.categories#cmp.strongord)
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#### 17.12.2.4 Class strong_ordering [cmp.strongord]
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5144)
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The strong_ordering type is typically used
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as the result type of a three-way comparison operator ([[expr.spaceship]](expr.spaceship "7.6.8 Three-way comparison operator"))
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for a type that admits
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all of the six two-way comparison operators ([[expr.rel]](expr.rel "7.6.9 Relational operators"), [[expr.eq]](expr.eq "7.6.10 Equality operators"))
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and for which equality does imply substitutability[.](#1.sentence-1)
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[ð](#lib:strong_ordering)
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namespace std {class strong_ordering {int *value*; // *exposition only*// exposition-only constructorsconstexpr explicit strong_ordering(*ord* v) noexcept : *value*(int(v)) {} // *exposition only*public:// valid valuesstatic const strong_ordering less; static const strong_ordering equal; static const strong_ordering equivalent; static const strong_ordering greater; // conversionsconstexpr operator partial_ordering() const noexcept; constexpr operator weak_ordering() const noexcept; // comparisonsfriend 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' definitionsinline constexpr strong_ordering strong_ordering::less(*ord*::*less*); inline constexpr strong_ordering strong_ordering::equal(*ord*::*equal*); inline constexpr strong_ordering strong_ordering::equivalent(*ord*::*equivalent*); inline constexpr strong_ordering strong_ordering::greater(*ord*::*greater*);}
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[ð](#lib:operator_partial_ordering,strong_ordering)
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`constexpr operator partial_ordering() const noexcept;
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`
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5204)
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*Returns*: *value* == 0 ? partial_ordering::equivalent :*value* < 0 ? partial_ordering::less : partial_ordering::greater
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[ð](#lib:operator_weak_ordering,strong_ordering)
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`constexpr operator weak_ordering() const noexcept;
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`
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5219)
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*Returns*: *value* == 0 ? weak_ordering::equivalent :*value* < 0 ? weak_ordering::less : weak_ordering::greater
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[ð](#lib:operator==,strong_ordering)
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`constexpr bool operator==(strong_ordering v, unspecified) noexcept;
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constexpr bool operator< (strong_ordering v, unspecified) noexcept;
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constexpr bool operator> (strong_ordering v, unspecified) noexcept;
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constexpr bool operator<=(strong_ordering v, unspecified) noexcept;
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constexpr bool operator>=(strong_ordering v, unspecified) noexcept;
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`
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5242)
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*Returns*: v.*value* @ 0 for operator@[.](#4.sentence-1)
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[ð](#lib:operator%3c,strong_ordering_)
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`constexpr bool operator< (unspecified, strong_ordering v) noexcept;
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constexpr bool operator> (unspecified, strong_ordering v) noexcept;
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constexpr bool operator<=(unspecified, strong_ordering v) noexcept;
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constexpr bool operator>=(unspecified, strong_ordering v) noexcept;
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`
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5259)
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*Returns*: 0 @ v.*value* for operator@[.](#5.sentence-1)
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[ð](#lib:operator%3c=%3e,strong_ordering)
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`constexpr strong_ordering operator<=>(strong_ordering v, unspecified) noexcept;
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`
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[6](#6)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5270)
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*Returns*: v[.](#6.sentence-1)
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[ð](#lib:operator%3c=%3e,strong_ordering_)
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`constexpr strong_ordering operator<=>(unspecified, strong_ordering v) noexcept;
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`
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[7](#7)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5281)
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*Returns*: v < 0 ? strong_ordering::greater : v > 0 ? strong_ordering::less : v[.](#7.sentence-1)
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