Change the implementation, in the way that mismatch in return
type of the from/to_sys/utc functions (not returning time_point,
or returning time_point with inappropriate clock) leads to
hard error.
Added appropariate fail test for to_sys function, including:
* returning an int
* returning time_point of wrong clock
* reutrning reference to time_point
Added test that detects if clock_cast<Dest>(Source) properly
SFINAEs if clock's are not castable, this includes test for
steady_clock that is not castable to any wall-clock.
Secondly added steady_based_clock based on steady_clock
(as name indicates), that clock_cast may be extended to clock
non-related to wall-time (sys/utc) using conversion traits.
Final example is pair of ambiguous clocks (amb1/amb2_clock) that can convert
to each other either using sys_clock or utc_clock.
Then the conversion from amb2 to amb1 is disambiguated
via trait specialization.
Created mil_clock and s2s_clock, that are both using to_sys/from_sys
function and are fully interoperable with existing clocks (including
ones based on utc).
Implemented an trait is used to provide direct conversion
from s2s_clock to mil_clock without converting to sys_clock
(conversion counter is used for this purpose).
Implemented test for conversions between existing clocks
(sys_clock, utc_clock, tai_clock, gps_clock) showing that
they can be used instead of to_clock_time functions.
* Avoids the need to download the IANA database.
* Heavily based on contributions by Aaron Bishop.
* Turn on with -DUSE_OS_TZDB, off by default.
* Not supported on Windows.
* Disables HAS_REMOTE_API.
* get_tzdb().version only supported on Apple. This string has
the value "unknown" elsewhere.
* Leap second support is missing on Apple, and may not be on your
platform either (please report). Leap second support is enabled,
disabled with -DMISSING_LEAP_SECONDS.
Without leap second support, utc_time, tai_time, and gps_time (and
those clocks) are not available.
* On Apple, time zone transitions are only supported in the range:
1901-12-13 20:45:52 to 2038-01-19 03:14:07
* On Linux, time zone transitions are only as far in the future as
the OS-provided transitions go. There is no support for POSIX-
style transitions.
* For format, all a type must do is implement to_stream.
* For parse, each type X must specialize parse_manip<X,CharT,Traits>.
Each specialization must include a public typedef to itself named
type.
* Each parse_manip specialization must have a stream extraction
operator.
* This commit depends on expression-SFINAE. If this commit breaks
your build, it is likely that your compiler/version does not
support expression-SFINAE. To fix this NO_EXPRESSION_SFINAE
needs to be defined in the configuration area of date.h for
that compiler/version.
Make validate work for C++11 because the library supports it.
Fix an unused variable mistake i made earlier.
Make constructor public, seems it should be. Possible compiler bug?
