Tomasz Kamiński e1099ef3ab Implemented clock_cast function. ...

Added an clock_time_conversion trait, that should be specialized
with SourceClock and DestClock respectively and provide an function
that convert time_point in SourceClock to equivalent time_point
in DestClock.

This function has following specializations:
1) <sys_clock, utc_clock> - convert sys_time to utc_time
2) <utc_clock, sys_clock> - convert utc_time to sys_time
3) <Clock, sys_clock>     - calls Clock::to_sys if it returns sys_time
4) <Clock, utc_clock>     - calls Clock::to_utc if it returns utc_time
5) <sys_clock, Clock>     - calls Clock::from_sys if it returns time_point<Clock>
5) <utc_clock, Clock>     - calls Clock::from_utc if it returns time_point<Clock>

Implemented an clock_cast<DestClock>(time_point<SourceClock, Dur> st), that
works as follow:
1) If DestClock is same as SourceClock, returns std
2) Otherwise, if clock_conversion<SourceClock, DestClock> available, uses it
3) Otherwise, if tries using clock_conversion<SourceClock, CommClock>
   and clock_conversion<CommClock, DestClock> for CommClock being utc_time
   or sys_time
4) Otherwise, tries using clock_conversion<SourceClock, utc_clock>
   and clock_conversion<sys_clock, DestinationClock> or reversed (firstly
   convert to sys_clock, then to utc_clock) to convert.

2017-11-24 17:55:15 +01:00

..

date

Implemented clock_cast function.

2017-11-24 17:55:15 +01:00