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P2592R3 Hashing support for std::chrono value classes #6332

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Merged
merged 1 commit into from
Jul 16, 2023
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P2592R3 Hashing support for std::chrono value classes #6332

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2 changes: 1 addition & 1 deletion source/support.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -585,7 +585,7 @@
#define @\defnlibxname{cpp_lib_byteswap}@ 202110L // also in \libheader{bit}
#define @\defnlibxname{cpp_lib_char8_t}@ 201907L
// also in \libheader{atomic}, \libheader{filesystem}, \libheader{istream}, \libheader{limits}, \libheader{locale}, \libheader{ostream}, \libheader{string}, \libheader{string_view}
#define @\defnlibxname{cpp_lib_chrono}@ 201907L // also in \libheader{chrono}
#define @\defnlibxname{cpp_lib_chrono}@ 202306L // also in \libheader{chrono}
#define @\defnlibxname{cpp_lib_chrono_udls}@ 201304L // also in \libheader{chrono}
#define @\defnlibxname{cpp_lib_clamp}@ 201603L // also in \libheader{algorithm}
#define @\defnlibxname{cpp_lib_common_reference}@ 202302L // also in \libheader{type_traits}
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120 changes: 120 additions & 0 deletions source/time.tex
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Original file line number Diff line number Diff line change
Expand Up @@ -942,6 +942,31 @@
namespace std::chrono {
using namespace literals::chrono_literals;
}

namespace std {
// \ref{time.hash}, hash support
template<class T> struct hash;
template<class Rep, class Period> struct hash<chrono::duration<Rep, Period>>;
template<class Clock, class Duration> struct hash<chrono::time_point<Clock, Duration>>;
template<> struct hash<chrono::day>;
template<> struct hash<chrono::month>;
template<> struct hash<chrono::year>;
template<> struct hash<chrono::weekday>;
template<> struct hash<chrono::weekday_indexed>;
template<> struct hash<chrono::weekday_last>;
template<> struct hash<chrono::month_day>;
template<> struct hash<chrono::month_day_last>;
template<> struct hash<chrono::month_weekday>;
template<> struct hash<chrono::month_weekday_last>;
template<> struct hash<chrono::year_month>;
template<> struct hash<chrono::year_month_day>;
template<> struct hash<chrono::year_month_day_last>;
template<> struct hash<chrono::year_month_weekday>;
template<> struct hash<chrono::year_month_weekday_last>;
template<class Duration, class TimeZonePtr>
struct hash<chrono::zoned_time<Duration, TimeZonePtr>>;
template<> struct hash<chrono::leap_second>;
}
\end{codeblock}

\rSec1[time.clock.req]{\oldconcept{Clock} requirements}
Expand Down Expand Up @@ -11449,6 +11474,101 @@

\indexlibrary{\idxcode{parse}|)}

\rSec1[time.hash]{Hash support}

\indexlibrarymember{hash}{duration}%
\begin{itemdecl}
template<class Rep, class Period> struct hash<chrono::duration<Rep, Period>>;
\end{itemdecl}

\begin{itemdescr}
\pnum
The specialization \tcode{hash<chrono::duration<Rep, Period>>} is enabled\iref{unord.hash}
if and only if \\% newline to fix overfull hbox
\tcode{hash<Rep>} is enabled.
The member functions are not guaranteed to be \keyword{noexcept}.
\end{itemdescr}

\indexlibrarymember{hash}{time_point}%
\begin{itemdecl}
template<class Clock, class Duration> struct hash<chrono::time_point<Clock, Duration>>;
\end{itemdecl}

\begin{itemdescr}
\pnum
The specialization \tcode{hash<chrono::time_point<Clock, Duration>>} is enabled\iref{unord.hash}
if and only if \tcode{hash<Duration>} is enabled.
The member functions are not guaranteed to be \keyword{noexcept}.
\end{itemdescr}

\indexlibrarymember{hash}{day}%
\indexlibrarymember{hash}{month}%
\indexlibrarymember{hash}{year}%
\indexlibrarymember{hash}{weekday}%
\indexlibrarymember{hash}{weekday_indexed}%
\indexlibrarymember{hash}{weekday_last}%
\indexlibrarymember{hash}{month_day}%
\indexlibrarymember{hash}{month_day_last}%
\indexlibrarymember{hash}{month_weekday}%
\indexlibrarymember{hash}{month_weekday_last}%
\indexlibrarymember{hash}{year_month}%
\indexlibrarymember{hash}{year_month_day}%
\indexlibrarymember{hash}{year_month_day_last}%
\indexlibrarymember{hash}{year_month_weekday}%
\indexlibrarymember{hash}{year_month_weekday_last}%
\begin{itemdecl}
template<> struct hash<chrono::day>;
template<> struct hash<chrono::month>;
template<> struct hash<chrono::year>;
template<> struct hash<chrono::weekday>;
template<> struct hash<chrono::weekday_indexed>;
template<> struct hash<chrono::weekday_last>;
template<> struct hash<chrono::month_day>;
template<> struct hash<chrono::month_day_last>;
template<> struct hash<chrono::month_weekday>;
template<> struct hash<chrono::month_weekday_last>;
template<> struct hash<chrono::year_month>;
template<> struct hash<chrono::year_month_day>;
template<> struct hash<chrono::year_month_day_last>;
template<> struct hash<chrono::year_month_weekday>;
template<> struct hash<chrono::year_month_weekday_last>;
\end{itemdecl}

\begin{itemdescr}
\pnum
The specializations are enabled\iref{unord.hash}.
\begin{note}
All the \tcode{hash<Key>} specializations listed above meet the
\oldconcept{Cpp17Hash} requirements, even when called on objects \tcode{k}
of type \tcode{Key} such that \tcode{k.ok()} is \tcode{false}.
\end{note}
\end{itemdescr}

\indexlibrarymember{hash}{zoned_time}%
\begin{itemdecl}
template<class Duration, class TimeZonePtr>
struct hash<chrono::zoned_time<Duration, TimeZonePtr>>;
\end{itemdecl}

\begin{itemdescr}
\pnum
The specialization \tcode{hash<chrono::zoned_time<Durationm TimeZonePtr>>}
is enabled\iref{unord.hash}
if and only if \tcode{hash<Duration>} is enabled and
\tcode{hash<TimeZonePtr>} is enabled.
The member functions are not guaranteed to be \keyword{noexcept}.
\end{itemdescr}

\indexlibrarymember{hash}{leap_second}%
\begin{itemdecl}
template<> struct hash<chrono::leap_second>;
\end{itemdecl}

\begin{itemdescr}
\pnum
The specialization is enabled\iref{unord.hash}.
\end{itemdescr}

\rSec1[ctime.syn]{Header \tcode{<ctime>} synopsis}

\indexheader{ctime}%
Expand Down