259 lines
7.7 KiB
Prolog
259 lines
7.7 KiB
Prolog
/* $Id$
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Part of SWI-Prolog
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Author: Jan Wielemaker and Willem Robert van Hage
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E-mail: wielemak@science.uva.nl
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WWW: http://www.swi-prolog.org
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Copyright (C): 1985-2005, University of Amsterdam
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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As a special exception, if you link this library with other files,
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compiled with a Free Software compiler, to produce an executable, this
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library does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however
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invalidate any other reasons why the executable file might be covered by
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the GNU General Public License.
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*/
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:- module(date,
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[ date_time_value/3, % ?Field, ?DaTime, ?Value
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parse_time/2, % +Date, -Stamp
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parse_time/3, % +Date, ?Format, -Stamp
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day_of_the_week/2 % +Date, -DayOfTheWeek
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]).
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/** <module> date time routines
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@ingroup swi
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*/
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%% date_time_value(?Field:atom, +Struct:datime, -Value) is nondet.
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%
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% Extract values from a date-time structure. Provided fields are
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%
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% | year | integer | |
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% | month | 1..12 | |
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% | day | 1..31 | |
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% | hour | 0..23 | |
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% | minute | 0..59 | |
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% | second | 0.0..60.0 | |
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% | utc_offset | integer | Offset to UTC in seconds (positive is west) |
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% | daylight_saving | bool | Name of timezone; fails if unknown |
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% | date | date(Y,M,D) | |
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% | time | time(H,M,S) | |
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date_time_value(year, date(Y,_,_,_,_,_,_,_,_), Y).
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date_time_value(month, date(_,M,_,_,_,_,_,_,_), M).
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date_time_value(day, date(_,_,D,_,_,_,_,_,_), D).
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date_time_value(hour, date(_,_,_,H,_,_,_,_,_), H).
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date_time_value(minute, date(_,_,_,_,M,_,_,_,_), M).
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date_time_value(second, date(_,_,_,_,_,S,_,_,_), S).
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date_time_value(utc_offset, date(_,_,_,_,_,_,O,_,_), O).
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date_time_value(time_zone, date(_,_,_,_,_,_,_,Z,_), Z) :- Z \== (-).
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date_time_value(daylight_saving, date(_,_,_,_,_,_,_,_,D), D) :- D \== (-).
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date_time_value(date, date(Y,M,D,_,_,_,_,_,_), date(Y,M,D)).
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date_time_value(time, date(_,_,_,H,M,S,_,_,_), time(H,M,S)).
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%% parse_time(+Text, -Stamp) is semidet.
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%% parse_time(+Text, ?Format, -Stamp) is semidet.
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%
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% Stamp is a timestamp created from parsing Text using the
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% representation Format. Currently supported formats are:
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%
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% * rfc_1123
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% Used for the HTTP protocol to represent time-stamps
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% * iso_8601
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% Commonly used in XML documents.
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parse_time(Text, Stamp) :-
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parse_time(Text, _Format, Stamp).
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parse_time(Text, Format, Stamp) :-
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atom_codes(Text, Codes),
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phrase(date(Format, Y,Mon,D,H,Min,S,UTCOffset), Codes), !,
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date_time_stamp(date(Y,Mon,D,H,Min,S,UTCOffset,-,-), Stamp).
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date(iso_8601, Yr, Mon, D, H, Min, S, 0) --> % BC
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"-", date(iso_8601, Y, Mon, D, H, Min, S, 0),
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{ Yr is -1 * Y }.
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date(iso_8601, Y, Mon, D, H, Min, S, 0) -->
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year(Y),
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iso_8601_rest(Y, Mon, D, H, Min, S).
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date(rfc_1123, Y, Mon, D, H, Min, S, 0) --> % RFC 1123: "Fri, 08 Dec 2006 15:29:44 GMT"
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day_name(_), ", ", ws,
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day_of_the_month(D), ws,
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month_name(Mon), ws,
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year(Y), ws,
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hour(H), ":", minute(Min), ":", second(S), ws,
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( "GMT"
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-> []
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; []
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).
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%% iso_8601_rest(+Year:int, -Mon, -Day, -H, -M, -S)
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%
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% Process ISO 8601 time-values after parsing the 4-digit year.
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iso_8601_rest(_, Mon, D, H, Min, S) -->
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"-", month(Mon), "-", day(D),
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opt_time(H, Min, S).
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iso_8601_rest(_, Mon, 0, 0, 0, 0) -->
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"-", month(Mon).
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iso_8601_rest(_, Mon, D, H, Min, S) -->
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month(Mon), day(D),
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opt_time(H, Min, S).
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iso_8601_rest(_, 1, D, H, Min, S) -->
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"-", ordinal(D),
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opt_time(H, Min, S).
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iso_8601_rest(Yr, 1, D, H, Min, S) -->
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"-W", week(W), "-", day_of_the_week(DW),
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opt_time(H, Min, S),
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{ week_ordinal(Yr, W, DW, D) }.
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iso_8601_rest(Yr, 1, D, H, Min, S) -->
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"W", week(W), day_of_the_week(DW),
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opt_time(H, Min, S),
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{ week_ordinal(Yr, W, DW, D) }.
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iso_8601_rest(Yr, 1, D, 0, 0, 0) -->
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"W", week(W),
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{ week_ordinal(Yr, W, 1, D) }.
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opt_time(Hr, Min, Sec) -->
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"T", !, iso_time(Hr, Min, Sec).
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opt_time(0, 0, 0) --> "".
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% TIMEX2 ISO: "2006-12-08T15:29:44 UTC" or "20061208T"
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iso_time(Hr, Min, Sec) -->
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hour(H), ":", minute(M), ":", second(S),
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timezone(DH, DM, DS),
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{ Hr is H + DH, Min is M + DM, Sec is S + DS }.
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iso_time(Hr, Min, Sec) -->
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hour(H), ":", minute(M),
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timezone(DH, DM, DS),
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{ Hr is H + DH, Min is M + DM, Sec is DS }.
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iso_time(Hr, Min, Sec) -->
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hour(H), minute(M), second(S),
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timezone(DH, DM, DS),
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{ Hr is H + DH, Min is M + DM, Sec is S + DS }.
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iso_time(Hr, Min, Sec) -->
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hour(H), minute(M),
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timezone(DH, DM, DS),
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{ Hr is H + DH, Min is M + DM, Sec is DS }.
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iso_time(Hr, Min, Sec) -->
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hour(H),
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timezone(DH, DM, DS),
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{ Hr is H + DH, Min is DM, Sec is DS }.
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% FIXME: deal with leap seconds
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timezone(Hr, Min, 0) -->
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"+", hour(H), ":", minute(M), { Hr is -1 * H, Min is -1 * M }.
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timezone(Hr, Min, 0) -->
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"+", hour(H), minute(M), { Hr is -1 * H, Min is -1 * M }.
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timezone(Hr, 0, 0) -->
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"+", hour(H), { Hr is -1 * H }.
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timezone(Hr, Min, 0) -->
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"-", hour(H), ":", minute(M), { Hr is H, Min is M }.
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timezone(Hr, Min, 0) -->
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"-", hour(H), minute(M), { Hr is H, Min is M }.
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timezone(Hr, 0, 0) -->
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"-", hour(H), { Hr is H }.
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timezone(0, 0, 0) -->
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"Z".
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timezone(0, 0, 0) -->
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ws, "UTC".
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timezone(0, 0, 0) -->
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ws, "GMT". % remove this?
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timezone(0, 0, 0) -->
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[].
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day_name(0) --> "Sun".
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day_name(1) --> "Mon".
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day_name(2) --> "Tue".
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day_name(3) --> "Wed".
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day_name(4) --> "Thu".
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day_name(5) --> "Fri".
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day_name(6) --> "Sat".
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day_name(7) --> "Sun".
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month_name(1) --> "Jan".
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month_name(2) --> "Feb".
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month_name(3) --> "Mar".
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month_name(4) --> "Apr".
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month_name(5) --> "May".
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month_name(6) --> "Jun".
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month_name(7) --> "Jul".
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month_name(8) --> "Aug".
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month_name(9) --> "Sep".
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month_name(10) --> "Oct".
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month_name(11) --> "Nov".
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month_name(12) --> "Dec".
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day_of_the_month(N) --> int2digit(N), { between(1, 31, N) }.
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day_of_the_week(N) --> digit(N), { between(1, 7, N) }.
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month(M) --> int2digit(M), { between(1, 12, M) }.
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week(W) --> int2digit(W), { between(1, 53, W) }.
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day(D) --> int2digit(D), { between(1, 31, D) }.
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hour(N) --> int2digit(N), { between(0, 23, N) }.
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minute(N) --> int2digit(N), { between(0, 59, N) }.
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second(N) --> int2digit(N), { between(0, 60, N) }. % leap second
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int2digit(N) -->
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digit(D0),
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digit(D1),
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{ N is D0*10+D1 }.
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year(Y) -->
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digit(D0),
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digit(D1),
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digit(D2),
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digit(D3),
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{ Y is D0*1000+D1*100+D2*10+D3 }.
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ordinal(N) --> % Nth day of the year, jan 1 = 1, dec 31 = 365 or 366
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digit(D0),
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digit(D1),
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digit(D2),
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{ N is D0*100+D1*10+D2, between(1, 366, N) }.
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digit(D) -->
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[C],
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{ code_type(C, digit(D)) }.
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ws -->
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" ", !,
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ws.
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ws -->
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[].
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%% day_of_the_week(+Date, -DayOfTheWeek) is det.
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%
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% Computes the day of the week for a given date.
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% Days of the week are numbered from one to seven:
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% monday = 1, tuesday = 2, ..., sunday = 7.
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%
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% @param Date is a term of the form date(+Year, +Month, +Day)
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day_of_the_week(date(Year, Mon, Day), DotW) :-
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format_time(atom(A), '%u', date(Year, Mon, Day, 0, 0, 0, 0, -, -)),
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atom_number(A, DotW).
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week_ordinal(Year, Week, Day, Ordinal) :-
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format_time(atom(A), '%w', date(Year, 1, 1, 0, 0, 0, 0, -, -)),
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atom_number(A, DotW0),
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Ordinal is ((Week-1) * 7) - DotW0 + Day + 1.
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