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set of utility functions that wrap the calendar module and erlangs now() date() and time() functions
-module(date_util).
-compile(export_all).
epoch() ->
now_to_seconds(now())
.
epoch_hires() ->
now_to_seconds_hires(now())
.
now_to_seconds({Mega, Sec, _}) ->
(Mega * 1000000) + Sec
.
now_to_milliseconds({Mega, Sec, Micro}) ->
now_to_seconds({Mega, Sec, Micro}) * 1000
.
now_to_seconds_hires({Mega, Sec, Micro}) ->
now_to_seconds({Mega, Sec, Micro}) + (Micro / 1000000)
.
now_to_milliseconds_hires({Mega, Sec, Micro}) ->
now_to_seconds_hires({Mega, Sec, Micro}) * 1000
.
epoch_gregorian_seconds() ->
calendar:datetime_to_gregorian_seconds({{1970,1,1}, {0,0,0}})
.
now_to_gregorian_seconds() ->
epoch_to_gregorian_seconds(now())
.
epoch_to_gregorian_seconds({Mega, Sec, Micro}) ->
epoch_to_gregorian_seconds(now_to_seconds({Mega, Sec, Micro}));
epoch_to_gregorian_seconds(Now) ->
EpochSecs = epoch_gregorian_seconds()
, Now + EpochSecs
.
gregorian_seconds_to_epoch(Secs) ->
EpochSecs = epoch_gregorian_seconds()
, Secs - EpochSecs
.
date_to_epoch(Date) ->
datetime_to_epoch({Date, {0,0,0} })
.
datetime_to_epoch({Date, Time}) ->
gregorian_seconds_to_epoch(
calendar:datetime_to_gregorian_seconds({Date, Time}))
.
is_older_by(T1, T2, {days, N}) ->
N1 = day_difference(T1, T2)
, case N1 of
N2 when (-N < N2) ->
true;
_ ->
false
end
.
is_sooner_by(T1, T2, {days, N}) ->
case day_difference(T1, T2) of
N1 when N > N1 ->
true;
_ ->
false
end
.
is_time_older_than({Date, Time}, Mark) ->
is_time_older_than(calendar:datetime_to_gregorian_seconds({Date, Time})
, Mark);
is_time_older_than(Time, {DateMark, TimeMark}) ->
is_time_older_than(Time
, calendar:datetime_to_gregorian_seconds({DateMark, TimeMark}));
is_time_older_than(Time, Mark) when is_integer(Time), is_integer(Mark) ->
Time < Mark
.
day_difference({D1, _}, D2) ->
day_difference(D1, D2);
day_difference(D1, {D2, _}) ->
day_difference(D1, D2);
day_difference(D1, D2) ->
Days1 = calendar:date_to_gregorian_days(D1)
, Days2 = calendar:date_to_gregorian_days(D2)
, Days1 - Days2
.
is_time_sooner_than({Date, Time}, Mark) ->
is_time_sooner_than(calendar:datetime_to_gregorian_seconds({Date, Time})
, Mark);
is_time_sooner_than(Time, {DateMark, TimeMark}) ->
is_time_sooner_than(Time
, calendar:datetime_to_gregorian_seconds({DateMark, TimeMark}));
is_time_sooner_than(Time, Mark) when is_integer(Time), is_integer(Mark) ->
Time > Mark
.
subtract(Date, {days, N}) ->
New = calendar:date_to_gregorian_days(Date) - N
, calendar:gregorian_days_to_date(New)
.
add(Date, {days, N}) ->
New = calendar:date_to_gregorian_days(Date) + N
, calendar:gregorian_days_to_date(New)
.
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