93 lines
3.1 KiB
Markdown
93 lines
3.1 KiB
Markdown
[time.hash]
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# 30 Time library [[time]](./#time)
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## 30.14 Hash support [time.hash]
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[ð](#lib:hash,duration)
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`template<class Rep, class Period> struct hash<chrono::duration<Rep, Period>>;
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L11501)
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The specialization hash<chrono::duration<Rep, Period>> is enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))
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if and only if
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hash<Rep> is enabled[.](#1.sentence-2)
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The member functions are not guaranteed to be noexcept[.](#1.sentence-3)
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[ð](#lib:hash,time_point)
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`template<class Clock, class Duration> struct hash<chrono::time_point<Clock, Duration>>;
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`
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L11514)
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The specialization hash<chrono::time_point<Clock, Duration>> is enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))
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if and only if hash<Duration> is enabled[.](#2.sentence-1)
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The member functions are not guaranteed to be noexcept[.](#2.sentence-2)
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[ð](#lib:hash,day)
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`template<> struct hash<chrono::day>;
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template<> struct hash<chrono::month>;
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template<> struct hash<chrono::year>;
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template<> struct hash<chrono::weekday>;
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template<> struct hash<chrono::weekday_indexed>;
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template<> struct hash<chrono::weekday_last>;
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template<> struct hash<chrono::month_day>;
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template<> struct hash<chrono::month_day_last>;
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template<> struct hash<chrono::month_weekday>;
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template<> struct hash<chrono::month_weekday_last>;
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template<> struct hash<chrono::year_month>;
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template<> struct hash<chrono::year_month_day>;
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template<> struct hash<chrono::year_month_day_last>;
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template<> struct hash<chrono::year_month_weekday>;
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template<> struct hash<chrono::year_month_weekday_last>;
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`
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L11554)
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The specializations are enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))[.](#3.sentence-1)
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[*Note [1](#note-1)*:
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All the hash<Key> specializations listed above meet the[*Cpp17Hash*](hash.requirements#:Cpp17Hash "16.4.4.5 Cpp17Hash requirements [hash.requirements]") requirements, even when called on objects k of type Key such that k.ok() is false[.](#3.sentence-2)
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â *end note*]
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[ð](#lib:hash,zoned_time)
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`template<class Duration, class TimeZonePtr>
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struct hash<chrono::zoned_time<Duration, TimeZonePtr>>;
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`
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L11570)
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The specialization hash<chrono::zoned_time<Duration, TimeZonePtr>> is enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))
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if and only if hash<Duration> is enabled andhash<TimeZonePtr> is enabled[.](#4.sentence-1)
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The member functions are not guaranteed to be noexcept[.](#4.sentence-2)
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[ð](#lib:hash,leap_second)
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`template<> struct hash<chrono::leap_second>;
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`
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L11584)
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The specialization is enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))[.](#5.sentence-1)
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