%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
-module(calendar).
%% local and universal time, time conversions
-export([date_to_gregorian_days/1,
date_to_gregorian_days/3,
datetime_to_gregorian_seconds/1,
day_of_the_week/1,
day_of_the_week/3,
gregorian_days_to_date/1,
gregorian_seconds_to_datetime/1,
is_leap_year/1,
iso_week_number/0,
iso_week_number/1,
last_day_of_the_month/2,
local_time/0,
local_time_to_universal_time/1,
local_time_to_universal_time/2,
local_time_to_universal_time_dst/1,
now_to_datetime/1, % = now_to_universal_time/1
now_to_local_time/1,
now_to_universal_time/1,
seconds_to_daystime/1,
seconds_to_time/1,
time_difference/2,
time_to_seconds/1,
universal_time/0,
universal_time_to_local_time/1,
valid_date/1,
valid_date/3]).
-deprecated([{local_time_to_universal_time,1}]).
-define(SECONDS_PER_MINUTE, 60).
-define(SECONDS_PER_HOUR, 3600).
-define(SECONDS_PER_DAY, 86400).
-define(DAYS_PER_YEAR, 365).
-define(DAYS_PER_LEAP_YEAR, 366).
-define(DAYS_PER_4YEARS, 1461).
-define(DAYS_PER_100YEARS, 36524).
-define(DAYS_PER_400YEARS, 146097).
-define(DAYS_FROM_0_TO_1970, 719528).
%%----------------------------------------------------------------------
%% Types
%%----------------------------------------------------------------------
-type year() :: non_neg_integer().
-type year1970() :: 1970..10000. % should probably be 1970..
-type month() :: 1..12.
-type day() :: 1..31.
-type hour() :: 0..23.
-type minute() :: 0..59.
-type second() :: 0..59.
-type daynum() :: 1..7.
-type ldom() :: 28 | 29 | 30 | 31. % last day of month
-type weeknum() :: 1..53.
-type t_now() :: {non_neg_integer(),non_neg_integer(),non_neg_integer()}.
-type t_date() :: {year(),month(),day()}.
-type t_time() :: {hour(),minute(),second()}.
-type t_datetime() :: {t_date(),t_time()}.
-type t_datetime1970() :: {{year1970(),month(),day()},t_time()}.
-type t_yearweeknum() :: {year(),weeknum()}.
%%----------------------------------------------------------------------
%% All dates are according the the Gregorian calendar. In this module
%% the Gregorian calendar is extended back to year 0 for convenience.
%%
%% A year Y is a leap year if and only if either
%%
%% (1) Y is divisible by 4, but not by 100, or
%% (2) Y is divisible by 400.
%%
%% Hence, e.g. 1996 is a leap year, 1900 is not, but 2000 is.
%%
%%
%% EXPORTS
%%
%% date_to_gregorian_days(Year, Month, Day) = Integer
%% date_to_gregorian_days({Year, Month, Day}) = Integer
%%
%% Computes the total number of days starting from year 0,
%% January 1st.
%%
%% df/2 catches the case Year<0
-spec date_to_gregorian_days(year(),month(),day()) -> non_neg_integer().
date_to_gregorian_days(Year, Month, Day) when is_integer(Day), Day > 0 ->
Last = last_day_of_the_month(Year, Month),
if
Day =< Last ->
dy(Year) + dm(Month) + df(Year, Month) + Day - 1
end.
-spec date_to_gregorian_days(t_date()) -> non_neg_integer().
date_to_gregorian_days({Year, Month, Day}) ->
date_to_gregorian_days(Year, Month, Day).
%% datetime_to_gregorian_seconds(DateTime) = Integer
%%
%% Computes the total number of seconds starting from year 0,
%% January 1st.
%%
-spec datetime_to_gregorian_seconds(t_datetime()) -> non_neg_integer().
datetime_to_gregorian_seconds({Date, Time}) ->
?SECONDS_PER_DAY*date_to_gregorian_days(Date) +
time_to_seconds(Time).
%% day_of_the_week(Year, Month, Day)
%% day_of_the_week({Year, Month, Day})
%%
%% Returns: 1 | .. | 7. Monday = 1, Tuesday = 2, ..., Sunday = 7.
%%
-spec day_of_the_week(year(), month(), day()) -> daynum().
day_of_the_week(Year, Month, Day) ->
(date_to_gregorian_days(Year, Month, Day) + 5) rem 7 + 1.
-spec day_of_the_week(t_date()) -> daynum().
day_of_the_week({Year, Month, Day}) ->
day_of_the_week(Year, Month, Day).
%% gregorian_days_to_date(Days) = {Year, Month, Day}
%%
-spec gregorian_days_to_date(non_neg_integer()) -> t_date().
gregorian_days_to_date(Days) ->
{Year, DayOfYear} = day_to_year(Days),
{Month, DayOfMonth} = year_day_to_date(Year, DayOfYear),
{Year, Month, DayOfMonth}.
%% gregorian_seconds_to_datetime(Secs)
%%
-spec gregorian_seconds_to_datetime(non_neg_integer()) -> t_datetime().
gregorian_seconds_to_datetime(Secs) when Secs >= 0 ->
Days = Secs div ?SECONDS_PER_DAY,
Rest = Secs rem ?SECONDS_PER_DAY,
{gregorian_days_to_date(Days), seconds_to_time(Rest)}.
%% is_leap_year(Year) = true | false
%%
-spec is_leap_year(year()) -> boolean().
is_leap_year(Y) when is_integer(Y), Y >= 0 ->
is_leap_year1(Y).
-spec is_leap_year1(year()) -> boolean().
is_leap_year1(Year) when Year rem 4 =:= 0, Year rem 100 > 0 ->
true;
is_leap_year1(Year) when Year rem 400 =:= 0 ->
true;
is_leap_year1(_) -> false.
%%
%% Calculates the iso week number for the current date.
%%
-spec iso_week_number() -> t_yearweeknum().
iso_week_number() ->
{Date, _} = local_time(),
iso_week_number(Date).
%%
%% Calculates the iso week number for the given date.
%%
-spec iso_week_number(t_date()) -> t_yearweeknum().
iso_week_number({Year, Month, Day}) ->
D = date_to_gregorian_days({Year, Month, Day}),
W01_1_Year = gregorian_days_of_iso_w01_1(Year),
W01_1_NextYear = gregorian_days_of_iso_w01_1(Year + 1),
if W01_1_Year =< D andalso D < W01_1_NextYear ->
% Current Year Week 01..52(,53)
{Year, (D - W01_1_Year) div 7 + 1};
D < W01_1_Year ->
% Previous Year 52 or 53
PWN = case day_of_the_week(Year - 1, 1, 1) of
4 -> 53;
_ -> case day_of_the_week(Year - 1, 12, 31) of
4 -> 53;
_ -> 52
end
end,
{Year - 1, PWN};
W01_1_NextYear =< D ->
% Next Year, Week 01
{Year + 1, 1}
end.
%% last_day_of_the_month(Year, Month)
%%
%% Returns the number of days in a month.
%%
-spec last_day_of_the_month(year(), month()) -> ldom().
last_day_of_the_month(Y, M) when is_integer(Y), Y >= 0 ->
last_day_of_the_month1(Y, M).
-spec last_day_of_the_month1(year(),month()) -> ldom().
last_day_of_the_month1(_, 4) -> 30;
last_day_of_the_month1(_, 6) -> 30;
last_day_of_the_month1(_, 9) -> 30;
last_day_of_the_month1(_,11) -> 30;
last_day_of_the_month1(Y, 2) ->
case is_leap_year(Y) of
true -> 29;
_ -> 28
end;
last_day_of_the_month1(_, M) when is_integer(M), M > 0, M < 13 ->
31.
%% local_time()
%%
%% Returns: {date(), time()}, date() = {Y, M, D}, time() = {H, M, S}.
-spec local_time() -> t_datetime().
local_time() ->
erlang:localtime().
%% local_time_to_universal_time(DateTime)
%%
-spec local_time_to_universal_time(t_datetime1970()) -> t_datetime1970().
local_time_to_universal_time(DateTime) ->
erlang:localtime_to_universaltime(DateTime).
-spec local_time_to_universal_time(t_datetime1970(),
'true' | 'false' | 'undefined') ->
t_datetime1970().
local_time_to_universal_time(DateTime, IsDst) ->
erlang:localtime_to_universaltime(DateTime, IsDst).
-spec local_time_to_universal_time_dst(t_datetime1970()) -> [t_datetime1970()].
local_time_to_universal_time_dst(DateTime) ->
UtDst = erlang:localtime_to_universaltime(DateTime, true),
Ut = erlang:localtime_to_universaltime(DateTime, false),
%% Reverse check the universal times
LtDst = erlang:universaltime_to_localtime(UtDst),
Lt = erlang:universaltime_to_localtime(Ut),
%% Return the valid universal times
case {LtDst,Lt} of
{DateTime,DateTime} when UtDst =/= Ut ->
[UtDst,Ut];
{DateTime,_} ->
[UtDst];
{_,DateTime} ->
[Ut];
{_,_} ->
[]
end.
%% now_to_universal_time(Now)
%% now_to_datetime(Now)
%%
%% Convert from now() to UTC.
%%
%% Args: Now = now(); now() = {MegaSec, Sec, MilliSec}, MegaSec = Sec
%% = MilliSec = integer()
%% Returns: {date(), time()}, date() = {Y, M, D}, time() = {H, M, S}.
%%
-spec now_to_datetime(t_now()) -> t_datetime1970().
now_to_datetime({MSec, Sec, _uSec}) ->
Sec0 = MSec*1000000 + Sec + ?DAYS_FROM_0_TO_1970*?SECONDS_PER_DAY,
gregorian_seconds_to_datetime(Sec0).
-spec now_to_universal_time(t_now()) -> t_datetime1970().
now_to_universal_time(Now) ->
now_to_datetime(Now).
%% now_to_local_time(Now)
%%
%% Args: Now = now()
%%
-spec now_to_local_time(t_now()) -> t_datetime1970().
now_to_local_time({MSec, Sec, _uSec}) ->
erlang:universaltime_to_localtime(
now_to_universal_time({MSec, Sec, _uSec})).
%% seconds_to_daystime(Secs) = {Days, {Hour, Minute, Second}}
%%
-spec seconds_to_daystime(integer()) -> {integer(), t_time()}.
seconds_to_daystime(Secs) ->
Days0 = Secs div ?SECONDS_PER_DAY,
Secs0 = Secs rem ?SECONDS_PER_DAY,
if
Secs0 < 0 ->
{Days0 - 1, seconds_to_time(Secs0 + ?SECONDS_PER_DAY)};
true ->
{Days0, seconds_to_time(Secs0)}
end.
%%
%% seconds_to_time(Secs)
%%
%% Wraps.
%%
-type secs_per_day() :: 0..?SECONDS_PER_DAY.
-spec seconds_to_time(secs_per_day()) -> t_time().
seconds_to_time(Secs) when Secs >= 0, Secs < ?SECONDS_PER_DAY ->
Secs0 = Secs rem ?SECONDS_PER_DAY,
Hour = Secs0 div ?SECONDS_PER_HOUR,
Secs1 = Secs0 rem ?SECONDS_PER_HOUR,
Minute = Secs1 div ?SECONDS_PER_MINUTE,
Second = Secs1 rem ?SECONDS_PER_MINUTE,
{Hour, Minute, Second}.
%% time_difference(T1, T2) = Tdiff
%%
%% Returns the difference between two {Date, Time} structures.
%%
%% T1 = T2 = {Date, Time}, Tdiff = {Day, {Hour, Min, Sec}},
%% Date = {Year, Month, Day}, Time = {Hour, Minute, Sec},
%% Year = Month = Day = Hour = Minute = Sec = integer()
%%
-type timediff() :: {integer(), t_time()}.
-spec time_difference(t_datetime(), t_datetime()) -> timediff().
time_difference({{Y1, Mo1, D1}, {H1, Mi1, S1}},
{{Y2, Mo2, D2}, {H2, Mi2, S2}}) ->
Secs = datetime_to_gregorian_seconds({{Y2, Mo2, D2}, {H2, Mi2, S2}}) -
datetime_to_gregorian_seconds({{Y1, Mo1, D1}, {H1, Mi1, S1}}),
seconds_to_daystime(Secs).
%%
%% time_to_seconds(Time)
%%
-spec time_to_seconds(t_time()) -> secs_per_day().
time_to_seconds({H, M, S}) when is_integer(H), is_integer(M), is_integer(S) ->
H * ?SECONDS_PER_HOUR +
M * ?SECONDS_PER_MINUTE + S.
%% universal_time()
%%
%% Returns: {date(), time()}, date() = {Y, M, D}, time() = {H, M, S}.
-spec universal_time() -> t_datetime().
universal_time() ->
erlang:universaltime().
%% universal_time_to_local_time(DateTime)
%%
-spec universal_time_to_local_time(t_datetime()) -> t_datetime().
universal_time_to_local_time(DateTime) ->
erlang:universaltime_to_localtime(DateTime).
%% valid_date(Year, Month, Day) = true | false
%% valid_date({Year, Month, Day}) = true | false
%%
-spec valid_date(integer(), integer(), integer()) -> boolean().
valid_date(Y, M, D) when is_integer(Y), is_integer(M), is_integer(D) ->
valid_date1(Y, M, D).
-spec valid_date1(integer(), integer(), integer()) -> boolean().
valid_date1(Y, M, D) when Y >= 0, M > 0, M < 13, D > 0 ->
D =< last_day_of_the_month(Y, M);
valid_date1(_, _, _) ->
false.
-spec valid_date({integer(),integer(),integer()}) -> boolean().
valid_date({Y, M, D}) ->
valid_date(Y, M, D).
%%
%% LOCAL FUNCTIONS
%%
-type day_of_year() :: 0..365.
%% day_to_year(DayOfEpoch) = {Year, DayOfYear}
%%
%% The idea here is to first guess a year, and then adjust. Although
%% the implementation is recursive, at most 1 or 2 recursive steps
%% are taken.
%% If DayOfEpoch is very large, we need far more than 1 or 2 iterations,
%% since we just subtract a yearful of days at a time until we're there.
%%
-spec day_to_year(non_neg_integer()) -> {year(), day_of_year()}.
day_to_year(DayOfEpoch) when DayOfEpoch >= 0 ->
Y0 = DayOfEpoch div ?DAYS_PER_YEAR,
{Y1, D1} = dty(Y0, DayOfEpoch, dy(Y0)),
{Y1, DayOfEpoch - D1}.
-spec dty(year(), non_neg_integer(), non_neg_integer()) ->
{year(), non_neg_integer()}.
dty(Y, D1, D2) when D1 < D2 ->
dty(Y-1, D1, dy(Y-1));
dty(Y, _D1, D2) ->
{Y, D2}.
%%
%% The Gregorian days of the iso week 01 day 1 for a given year.
%%
-spec gregorian_days_of_iso_w01_1(year()) -> non_neg_integer().
gregorian_days_of_iso_w01_1(Year) ->
D0101 = date_to_gregorian_days(Year, 1, 1),
DOW = day_of_the_week(Year, 1, 1),
if DOW =< 4 ->
D0101 - DOW + 1;
true ->
D0101 + 7 - DOW + 1
end.
%% year_day_to_date(Year, DayOfYear) = {Month, DayOfMonth}
%%
%% Note: 1 is the first day of the month.
%%
-spec year_day_to_date(year(), day_of_year()) -> {month(), day()}.
year_day_to_date(Year, DayOfYear) ->
ExtraDay = case is_leap_year(Year) of
true ->
1;
false ->
0
end,
{Month, Day} = year_day_to_date2(ExtraDay, DayOfYear),
{Month, Day + 1}.
%% Note: 0 is the first day of the month
%%
-spec year_day_to_date2(0 | 1, day_of_year()) -> {month(), 0..30}.
year_day_to_date2(_, Day) when Day < 31 ->
{1, Day};
year_day_to_date2(E, Day) when 31 =< Day, Day < 59 + E ->
{2, Day - 31};
year_day_to_date2(E, Day) when 59 + E =< Day, Day < 90 + E ->
{3, Day - (59 + E)};
year_day_to_date2(E, Day) when 90 + E =< Day, Day < 120 + E ->
{4, Day - (90 + E)};
year_day_to_date2(E, Day) when 120 + E =< Day, Day < 151 + E ->
{5, Day - (120 + E)};
year_day_to_date2(E, Day) when 151 + E =< Day, Day < 181 + E ->
{6, Day - (151 + E)};
year_day_to_date2(E, Day) when 181 + E =< Day, Day < 212 + E ->
{7, Day - (181 + E)};
year_day_to_date2(E, Day) when 212 + E =< Day, Day < 243 + E ->
{8, Day - (212 + E)};
year_day_to_date2(E, Day) when 243 + E =< Day, Day < 273 + E ->
{9, Day - (243 + E)};
year_day_to_date2(E, Day) when 273 + E =< Day, Day < 304 + E ->
{10, Day - (273 + E)};
year_day_to_date2(E, Day) when 304 + E =< Day, Day < 334 + E ->
{11, Day - (304 + E)};
year_day_to_date2(E, Day) when 334 + E =< Day ->
{12, Day - (334 + E)}.
%% dy(Year)
%%
%% Days in previous years.
%%
-spec dy(integer()) -> non_neg_integer().
dy(Y) when Y =< 0 ->
0;
dy(Y) ->
X = Y - 1,
(X div 4) - (X div 100) + (X div 400) +
X*?DAYS_PER_YEAR + ?DAYS_PER_LEAP_YEAR.
%% dm(Month)
%%
%% Returns the total number of days in all months
%% preceeding Month, for an ordinary year.
%%
-spec dm(month()) ->
0 | 31 | 59 | 90 | 120 | 151 | 181 | 212 | 243 | 273 | 304 | 334.
dm(1) -> 0; dm(2) -> 31; dm(3) -> 59; dm(4) -> 90;
dm(5) -> 120; dm(6) -> 151; dm(7) -> 181; dm(8) -> 212;
dm(9) -> 243; dm(10) -> 273; dm(11) -> 304; dm(12) -> 334.
%% df(Year, Month)
%%
%% Accounts for an extra day in February if Year is
%% a leap year, and if Month > 2.
%%
-spec df(year(), month()) -> 0 | 1.
df(_, Month) when Month < 3 ->
0;
df(Year, _) ->
case is_leap_year(Year) of
true -> 1;
false -> 0
end.
