/* Part of SWI-Prolog
Author: Jan Wielemaker and Willem Robert van Hage
E-mail: wielemak@science.uva.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2006-2014, University of Amsterdam
All rights reserved.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/
:- module(date,
[ date_time_value/3, % ?Field, ?DaTime, ?Value
parse_time/2, % +Date, -Stamp
parse_time/3, % +Date, ?Format, -Stamp
day_of_the_week/2, % +Date, -DayOfTheWeek
day_of_the_year/2 % +Date, -DayOfTheYear
]).
/** <module> Process dates and times
*/
%! date_time_value(?Field:atom, +Struct:datime, -Value) is nondet.
%
% Extract values from a date-time structure. Provided fields are
%
% | year | integer | |
% | month | 1..12 | |
% | day | 1..31 | |
% | hour | 0..23 | |
% | minute | 0..59 | |
% | second | 0.0..60.0 | |
% | utc_offset | integer | Offset to UTC in seconds (positive is west) |
% | daylight_saving | bool | Name of timezone; fails if unknown |
% | date | date(Y,M,D) | |
% | time | time(H,M,S) | |
date_time_value(year, date(Y,_,_,_,_,_,_,_,_), Y).
date_time_value(month, date(_,M,_,_,_,_,_,_,_), M).
date_time_value(day, date(_,_,D,_,_,_,_,_,_), D).
date_time_value(hour, date(_,_,_,H,_,_,_,_,_), H).
date_time_value(minute, date(_,_,_,_,M,_,_,_,_), M).
date_time_value(second, date(_,_,_,_,_,S,_,_,_), S).
date_time_value(utc_offset, date(_,_,_,_,_,_,O,_,_), O).
date_time_value(time_zone, date(_,_,_,_,_,_,_,Z,_), Z) :- Z \== (-).
date_time_value(daylight_saving, date(_,_,_,_,_,_,_,_,D), D) :- D \== (-).
date_time_value(date, date(Y,M,D,_,_,_,_,_,_), date(Y,M,D)).
date_time_value(time, date(_,_,_,H,M,S,_,_,_), time(H,M,S)).
%! parse_time(+Text, -Stamp) is semidet.
%! parse_time(+Text, ?Format, -Stamp) is semidet.
%
% Stamp is a timestamp created from parsing Text using the
% representation Format. Currently supported formats are:
%
% * rfc_1123
% Used for the HTTP protocol to represent time-stamps
% * iso_8601
% Commonly used in XML documents.
parse_time(Text, Stamp) :-
parse_time(Text, _Format, Stamp).
parse_time(Text, Format, Stamp) :-
atom_codes(Text, Codes),
phrase(date(Format, Y,Mon,D,H,Min,S,UTCOffset), Codes),
!,
date_time_stamp(date(Y,Mon,D,H,Min,S,UTCOffset,-,-), Stamp).
date(iso_8601, Yr, Mon, D, H, Min, S, 0) --> % BC
"-", date(iso_8601, Y, Mon, D, H, Min, S, 0),
{ Yr is -1 * Y }.
date(iso_8601, Y, Mon, D, H, Min, S, 0) -->
year(Y),
iso_8601_rest(Y, Mon, D, H, Min, S).
date(rfc_1123, Y, Mon, D, Hr, Min, Sec, 0) --> % RFC 1123: "Fri, 08 Dec 2006 15:29:44 GMT"
day_name(_), ", ", ws,
day_of_the_month(D), ws,
month_name(Mon), ws,
year(Y), ws,
hour(H), ":", minute(M), ":", second(S), ws,
timezone(DH, DM, DS),
{ Hr is H + DH, Min is M + DM, Sec is S + DS }.
%! iso_8601_rest(+Year:int, -Mon, -Day, -H, -M, -S)
%
% Process ISO 8601 time-values after parsing the 4-digit year.
iso_8601_rest(_, Mon, D, H, Min, S) -->
"-", month(Mon), "-", day(D),
opt_time(H, Min, S).
iso_8601_rest(_, Mon, 0, 0, 0, 0) -->
"-", month(Mon).
iso_8601_rest(_, Mon, D, H, Min, S) -->
month(Mon), day(D),
opt_time(H, Min, S).
iso_8601_rest(_, 1, D, H, Min, S) -->
"-", ordinal(D),
opt_time(H, Min, S).
iso_8601_rest(Yr, 1, D, H, Min, S) -->
"-W", week(W), "-", day_of_the_week(DW),
opt_time(H, Min, S),
{ week_ordinal(Yr, W, DW, D) }.
iso_8601_rest(Yr, 1, D, H, Min, S) -->
"W", week(W), day_of_the_week(DW),
opt_time(H, Min, S),
{ week_ordinal(Yr, W, DW, D) }.
iso_8601_rest(Yr, 1, D, 0, 0, 0) -->
"W", week(W),
{ week_ordinal(Yr, W, 1, D) }.
opt_time(Hr, Min, Sec) -->
("T";" "), !, iso_time(Hr, Min, Sec).
opt_time(0, 0, 0) --> "".
% TIMEX2 ISO: "2006-12-08T15:29:44 UTC" or "20061208T"
iso_time(Hr, Min, Sec) -->
hour(H), ":", minute(M), ":", second(S),
timezone(DH, DM, DS),
{ Hr is H + DH, Min is M + DM, Sec is S + DS }.
iso_time(Hr, Min, Sec) -->
hour(H), ":", minute(M),
timezone(DH, DM, DS),
{ Hr is H + DH, Min is M + DM, Sec is DS }.
iso_time(Hr, Min, Sec) -->
hour(H), minute(M), second(S),
timezone(DH, DM, DS),
{ Hr is H + DH, Min is M + DM, Sec is S + DS }.
iso_time(Hr, Min, Sec) -->
hour(H), minute(M),
timezone(DH, DM, DS),
{ Hr is H + DH, Min is M + DM, Sec is DS }.
iso_time(Hr, Min, Sec) -->
hour(H),
timezone(DH, DM, DS),
{ Hr is H + DH, Min is DM, Sec is DS }.
% FIXME: deal with leap seconds
timezone(Hr, Min, 0) -->
"+", hour(H), ":", minute(M), { Hr is -1 * H, Min is -1 * M }.
timezone(Hr, Min, 0) -->
"+", hour(H), minute(M), { Hr is -1 * H, Min is -1 * M }.
timezone(Hr, 0, 0) -->
"+", hour(H), { Hr is -1 * H }.
timezone(Hr, Min, 0) -->
"-", hour(H), ":", minute(M), { Hr is H, Min is M }.
timezone(Hr, Min, 0) -->
"-", hour(H), minute(M), { Hr is H, Min is M }.
timezone(Hr, 0, 0) -->
"-", hour(H), { Hr is H }.
timezone(0, 0, 0) -->
"Z".
timezone(0, 0, 0) -->
ws, "UTC".
timezone(0, 0, 0) -->
ws, "GMT". % remove this?
timezone(0, 0, 0) -->
[].
day_name(0) --> "Sun".
day_name(1) --> "Mon".
day_name(2) --> "Tue".
day_name(3) --> "Wed".
day_name(4) --> "Thu".
day_name(5) --> "Fri".
day_name(6) --> "Sat".
day_name(7) --> "Sun".
month_name(1) --> "Jan".
month_name(2) --> "Feb".
month_name(3) --> "Mar".
month_name(4) --> "Apr".
month_name(5) --> "May".
month_name(6) --> "Jun".
month_name(7) --> "Jul".
month_name(8) --> "Aug".
month_name(9) --> "Sep".
month_name(10) --> "Oct".
month_name(11) --> "Nov".
month_name(12) --> "Dec".
day_of_the_month(N) --> int2digit(N), { between(1, 31, N) }.
day_of_the_week(N) --> digit(N), { between(1, 7, N) }.
month(M) --> int2digit(M), { between(1, 12, M) }.
week(W) --> int2digit(W), { between(1, 53, W) }.
day(D) --> int2digit(D), { between(1, 31, D) }.
hour(N) --> int2digit(N), { between(0, 23, N) }.
minute(N) --> int2digit(N), { between(0, 59, N) }.
second(S) --> int2digit(N), { between(0, 60, N) }, % leap second
opt_fraction(N, S).
opt_fraction(I, F) -->
( "." ; "," ),
!,
digits(D),
{ length(D, N),
N > 0,
number_codes(FP, D),
F is I + FP/(10^N)
}.
opt_fraction(I, I) -->
[].
int2digit(N) -->
digit(D0),
digit(D1),
{ N is D0*10+D1 }.
year(Y) -->
digit(D0),
digit(D1),
digit(D2),
digit(D3),
{ Y is D0*1000+D1*100+D2*10+D3 }.
ordinal(N) --> % Nth day of the year, jan 1 = 1, dec 31 = 365 or 366
digit(D0),
digit(D1),
digit(D2),
{ N is D0*100+D1*10+D2, between(1, 366, N) }.
digit(D) -->
[C],
{ code_type(C, digit(D)) }.
digits([C|T]) -->
[C],
{ code_type(C, digit) },
!,
digits(T).
digits([]) --> [].
ws -->
" ",
!,
ws.
ws -->
[].
%! day_of_the_week(+Date, -DayOfTheWeek) is det.
%
% Computes the day of the week for a given date. Days of the week
% are numbered from one to seven: monday = 1, tuesday = 2, ...,
% sunday = 7.
%
% @param Date is a term of the form date(+Year, +Month, +Day)
day_of_the_week(date(Year, Mon, Day), DotW) :-
format_time(atom(A), '%u', date(Year, Mon, Day, 0, 0, 0, 0, -, -)),
atom_number(A, DotW).
week_ordinal(Year, Week, Day, Ordinal) :-
format_time(atom(A), '%w', date(Year, 1, 1, 0, 0, 0, 0, -, -)),
atom_number(A, DotW0),
Ordinal is ((Week-1) * 7) - DotW0 + Day + 1.
%! day_of_the_year(+Date, -DayOfTheYear) is det.
%
% Computes the day of the year for a given date. Days of the year
% are numbered from 1 to 365 (366 for a leap year).
%
% @param Date is a term of the form date(+Year, +Month, +Day)
day_of_the_year(date(Year, Mon, Day), DotY) :-
format_time(atom(A), '%j', date(Year, Mon, Day, 0, 0, 0, 0, -, -)),
atom_number(A, DotY).