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Implemented clock_cast for local_time.

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Implemented clock_time_conversion<D, local_t> calling D::from_local
and clock_time_conversion<locat_t, S> calling S::to_local.

To avoid ambiguities addes:
* clock_time_conversion<local_t, local_t> - idenitity
* clock_time_conversion<local_t, utc_clock> - same as default (utc_clock::to_local)
* clock_time_conversion<utc_clock, local_t> - same as default (utc_clock::from_local)

In addition, as std::chrono::system_clock cannot be edited, added:
* clock_time_conversion<local_t, std::chrono::system_clock> - assumes same epoch
* clock_time_conversion<std::chrono::system_clock, local_t> - assumes same epoch
They will be required to resolve amibiguity anyway.
This commit is contained in:
Tomasz Kamiński 2017-11-28 15:20:45 +01:00 committed by Howard Hinnant
parent da15227f6c
commit 9f1c4b0110
1 changed files with 116 additions and 1 deletions
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117
include/date/tz.h
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@ -2293,6 +2293,17 @@ struct clock_time_conversion<utc_clock, utc_clock>
}
};
template<>
struct clock_time_conversion<local_t, local_t>
{
template <class Duration>
local_time<Duration>
operator()(const local_time<Duration>& lt) const
{
return lt;
}
};
template <>
struct clock_time_conversion<utc_clock, std::chrono::system_clock>
{
@ -2315,7 +2326,51 @@ struct clock_time_conversion<std::chrono::system_clock, utc_clock>
}
};
template <class Clock>
template<>
struct clock_time_conversion<local_t, std::chrono::system_clock>
{
template <class Duration>
local_time<Duration>
operator()(const sys_time<Duration>& st) const
{
return local_time<Duration>{st.time_since_epoch()};
}
};
template<>
struct clock_time_conversion<std::chrono::system_clock, local_t>
{
template <class Duration>
sys_time<Duration>
operator()(const local_time<Duration>& lt) const
{
return sys_time<Duration>{lt.time_sine_epoch()};
}
};
template<>
struct clock_time_conversion<utc_clock, local_t>
{
template <class Duration>
utc_time<typename std::common_type<Duration, std::chrono::seconds>::type>
operator()(const local_time<Duration>& lt) const
{
return utc_clock::from_local(lt);
}
};
template<>
struct clock_time_conversion<local_t, utc_clock>
{
template <class Duration>
local_time<typename std::common_type<Duration, std::chrono::seconds>::type>
operator()(const utc_time<Duration>& ut) const
{
return utc_clock::to_local(ut);
}
};
template<typename Clock>
struct clock_time_conversion<Clock, Clock>
{
template <class Duration>
@ -2421,6 +2476,44 @@ struct return_from_utc
>
{};
// Similiar to above
template<typename Clock, typename Duration, typename = void>
struct return_to_local
{};
template<typename Clock, typename Duration>
struct return_to_local
<
Clock, Duration,
decltype(Clock::to_local(declval<time_point<Clock, Duration> const&>()),
void())
>
: return_clock_time
<
local_t,
decltype(Clock::to_local(declval<time_point<Clock, Duration> const&>()))
>
{};
// Similiar to above
template<typename Clock, typename Duration, typename = void>
struct return_from_local
{};
template<typename Clock, typename Duration>
struct return_from_local
<
Clock, Duration,
decltype(Clock::from_local(declval<time_point<local_t, Duration> const&>()),
void())
>
: return_clock_time
<
Clock,
decltype(Clock::from_local(declval<time_point<local_t, Duration> const&>()))
>
{};
} // namespace ctc_detail
template <class SrcClock>
@ -2467,6 +2560,28 @@ struct clock_time_conversion<DstClock, utc_clock>
}
};
template<typename SrcClock>
struct clock_time_conversion<local_t, SrcClock>
{
template <class Duration>
typename ctc_detail::return_to_local<SrcClock, Duration>::type
operator()(const std::chrono::time_point<SrcClock, Duration>& tp) const
{
return SrcClock::to_local(tp);
}
};
template<typename DstClock>
struct clock_time_conversion<DstClock, local_t>
{
template <class Duration>
typename ctc_detail::return_from_local<DstClock, Duration>::type
operator()(const local_time<Duration>& lt) const
{
return DstClock::from_local(lt);
}
};
namespace clock_cast_detail
{