[bpt/emacs.git] / lisp / timezone.el

;;; Timezone package for GNU Emacs

;; Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.

;;; Author: Masanobu Umeda
;;; Maintainer: umerin@mse.kyutech.ac.jp
;;; Keywords: news

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Code:

(provide 'timezone)

(defvar timezone-world-timezones
  '(("PST" .  -800)
    ("PDT" .  -700)
    ("MST" .  -700)
    ("MDT" .  -600)
    ("CST" .  -600)
    ("CDT" .  -500)
    ("EST" .  -500)
    ("EDT" .  -400)
    ("AST" .  -400)			;by <clamen@CS.CMU.EDU>
    ("NST" .  -330)			;by <clamen@CS.CMU.EDU>
    ("UT"  .  +000)
    ("GMT" .  +000)
    ("BST" .  +100)
    ("MET" .  +100)
    ("EET" .  +200)
    ("JST" .  +900)
    ("GMT+1"  .  +100) ("GMT+2"  .  +200) ("GMT+3"  .  +300)
    ("GMT+4"  .  +400) ("GMT+5"  .  +500) ("GMT+6"  .  +600)
    ("GMT+7"  .  +700) ("GMT+8"  .  +800) ("GMT+9"  .  +900)
    ("GMT+10" . +1000) ("GMT+11" . +1100) ("GMT+12" . +1200) ("GMT+13" . +1300)
    ("GMT-1"  .  -100) ("GMT-2"  .  -200) ("GMT-3"  .  -300)
    ("GMT-4"  .  -400) ("GMT-5"  .  -500) ("GMT-6"  .  -600)
    ("GMT-7"  .  -700) ("GMT-8"  .  -800) ("GMT-9"  .  -900)
    ("GMT-10" . -1000) ("GMT-11" . -1100) ("GMT-12" . -1200))
  "*Time differentials of timezone from GMT in +-HHMM form.
This list is obsolescent, and is present only for backwards compatibility,
because time zone names are ambiguous in practice.
Use `current-time-zone' instead.")

(defvar timezone-months-assoc
  '(("JAN" .  1)("FEB" .  2)("MAR" .  3)
    ("APR" .  4)("MAY" .  5)("JUN" .  6)
    ("JUL" .  7)("AUG" .  8)("SEP" .  9)
    ("OCT" . 10)("NOV" . 11)("DEC" . 12))
  "Alist of first three letters of a month and its numerical representation.")

(defun timezone-make-date-arpa-standard (date &optional local timezone)
  "Convert DATE to an arpanet standard date.
Optional 1st argument LOCAL specifies the default local timezone of the DATE;
if nil, GMT is assumed.
Optional 2nd argument TIMEZONE specifies a time zone to be represented in;
if nil, the local time zone is assumed."
  (let ((new (timezone-fix-time date local timezone)))
    (timezone-make-arpa-date (aref new 0) (aref new 1) (aref new 2)
			     (timezone-make-time-string
			      (aref new 3) (aref new 4) (aref new 5))
			     (aref new 6))
    ))

(defun timezone-make-date-sortable (date &optional local timezone)
  "Convert DATE to a sortable date string.
Optional 1st argument LOCAL specifies the default local timezone of the DATE;
if nil, GMT is assumed.
Optional 2nd argument TIMEZONE specifies a timezone to be represented in;
if nil, the local time zone is assumed."
  (let ((new (timezone-fix-time date local timezone)))
    (timezone-make-sortable-date (aref new 0) (aref new 1) (aref new 2)
				 (timezone-make-time-string
				  (aref new 3) (aref new 4) (aref new 5)))
    ))

\f
;;
;; Parsers and Constructors of Date and Time
;;

(defun timezone-make-arpa-date (year month day time &optional timezone)
  "Make arpanet standard date string from YEAR, MONTH, DAY, and TIME.
Optional argument TIMEZONE specifies a time zone."
  (let ((zone
	 (if (listp timezone)
	     (let* ((m (timezone-zone-to-minute timezone))
		    (absm (if (< m 0) (- m) m)))
	       (format "%c%02d%02d"
		       (if (< m 0) ?- ?+) (/ absm 60) (% absm 60)))
	   timezone)))
    (format "%02d %s %04d %s %s"
	    day
	    (capitalize (car (rassq month timezone-months-assoc)))
	    year
	    time
	    zone)))

(defun timezone-make-sortable-date (year month day time)
  "Make sortable date string from YEAR, MONTH, DAY, and TIME."
  (format "%4d%02d%02d%s"
	  year month day time))

(defun timezone-make-time-string (hour minute second)
  "Make time string from HOUR, MINUTE, and SECOND."
  (format "%02d:%02d:%02d" hour minute second))

(defun timezone-parse-date (date)
  "Parse DATE and return a vector [YEAR MONTH DAY TIME TIMEZONE].
19 is prepended to year if necessary.  Timezone may be nil if nothing.
Understands the following styles:
 (1) 14 Apr 89 03:20[:12] [GMT]
 (2) Fri, 17 Mar 89 4:01[:33] [GMT]
 (3) Mon Jan 16 16:12[:37] [GMT] 1989
 (4) 6 May 1992 1641-JST (Wednesday)
 (5) 22-AUG-1993 10:59:12.82
 (6) Thu, 11 Apr 16:17:12 91 [MET]
 (7) Mon, 6  Jul 16:47:20 T 1992 [MET]"
  (let ((date (or date ""))
	(year nil)
	(month nil)
	(day nil)
	(time nil)
	(zone nil))			;This may be nil.
    (cond ((string-match
	    "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\'" date)
	   ;; Styles: (6) and (7) without timezone
	   (setq year 6 month 3 day 2 time 4 zone nil))
	  ((string-match
	    "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	   ;; Styles: (6) and (7) with timezone and buggy timezone
	   (setq year 6 month 3 day 2 time 4 zone 7))
	  ((string-match
	    "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\'" date)
	   ;; Styles: (1) and (2) without timezone
	   (setq year 3 month 2 day 1 time 4 zone nil))
	  ((string-match
	    "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	   ;; Styles: (1) and (2) with timezone and buggy timezone
	   (setq year 3 month 2 day 1 time 4 zone 5))
	  ((string-match
	    "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([0-9]+\\)" date)
	   ;; Styles: (3) without timezone
	   (setq year 4 month 1 day 2 time 3 zone nil))
	  ((string-match
	    "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)[ \t]+\\([0-9]+\\)" date)
	   ;; Styles: (3) with timezone
	   (setq year 5 month 1 day 2 time 3 zone 4))
	  ((string-match
	    "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	   ;; Styles: (4) with timezone
	   (setq year 3 month 2 day 1 time 4 zone 5))
	  ((string-match
	    "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\.[0-9]+" date)
	   ;; Styles: (5) without timezone.
	   (setq year 3 month 2 day 1 time 4 zone nil))
	  )
    (if year
	(progn
	  (setq year
		(substring date (match-beginning year) (match-end year)))
	  ;; It is now Dec 1992.  8 years before the end of the World.
	  (if (< (length year) 4)
	      (setq year (concat "19" (substring year -2 nil))))
	  (setq month
		(int-to-string
		 (cdr
		  (assoc
		   (upcase
		    ;; Don't use `match-end' in order to take 3
		    ;; letters from the beginning.
		    (substring date
			       (match-beginning month)
			       (+ (match-beginning month) 3)))
		   timezone-months-assoc))))
	  (setq day
		(substring date (match-beginning day) (match-end day)))
	  (setq time
		(substring date (match-beginning time) (match-end time)))))
    (if zone
	(setq zone
	      (substring date (match-beginning zone) (match-end zone))))
    ;; Return a vector.
    (if year
	(vector year month day time zone)
      (vector "0" "0" "0" "0" nil))
    ))

(defun timezone-parse-time (time)
  "Parse TIME (HH:MM:SS) and return a vector [hour minute second].
Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
  (let ((time (or time ""))
	(hour nil)
	(minute nil)
	(second nil))
    (cond ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)\\'" time)
	   ;; HH:MM:SS
	   (setq hour 1 minute 2 second 3))
	  ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\)\\'" time)
	   ;; HH:MM
	   (setq hour 1 minute 2 second nil))
	  ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
	   ;; HHMMSS
	   (setq hour 1 minute 2 second 3))
	  ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
	   ;; HHMM
	   (setq hour 1 minute 2 second nil))
	  )
    ;; Return [hour minute second]
    (vector
     (if hour
	 (substring time (match-beginning hour) (match-end hour)) "0")
     (if minute
	 (substring time (match-beginning minute) (match-end minute)) "0")
     (if second
	 (substring time (match-beginning second) (match-end second)) "0"))
    ))

\f
;; Miscellaneous

(defun timezone-zone-to-minute (timezone)
  "Translate TIMEZONE to an integer minute offset from GMT.
TIMEZONE can be a cons cell containing the output of current-time-zone,
or an integer of the form +-HHMM, or a time zone name."
  (cond
     ((consp timezone)
      (/ (car timezone) 60))
     (timezone
      (progn
	(setq timezone
	      (or (cdr (assoc (upcase timezone) timezone-world-timezones))
		  ;; +900
		  timezone))
	(if (stringp timezone)
	    (setq timezone (string-to-int timezone)))
	;; Taking account of minute in timezone.
	;; HHMM -> MM
	(let* ((abszone (abs timezone))
 	       (minutes (+ (* 60 (/ abszone 100)) (% abszone 100))))
 	  (if (< timezone 0) (- minutes) minutes))))
     (t 0)))

(defun timezone-time-from-absolute (date seconds)
  "Compute the UTC time equivalent to DATE at time SECONDS after midnight.
Return a list suitable as an argument to current-time-zone,
or nil if the date cannot be thus represented.
DATE is the number of days elapsed since the (imaginary)
Gregorian date Sunday, December 31, 1 BC."
  (let* ((current-time-origin 719162)
	    ;; (timezone-absolute-from-gregorian 1 1 1970)
	 (days (- date current-time-origin))
	 (seconds-per-day (float 86400))
	 (seconds (+ seconds (* days seconds-per-day)))
	 (current-time-arithmetic-base (float 65536))
	 (hi (floor (/ seconds current-time-arithmetic-base)))
	 (hibase (* hi current-time-arithmetic-base))
	 (lo (floor (- seconds hibase))))
     (and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow.
	  (cons hi lo))))

(defun timezone-time-zone-from-absolute (date seconds)
  "Compute the local time zone for DATE at time SECONDS after midnight.
Return a list in the same format as current-time-zone's result,
or nil if the local time zone could not be computed.
DATE is the number of days elapsed since the (imaginary)
Gregorian date Sunday, December 31, 1 BC."
   (and (fboundp 'current-time-zone)
	(let ((utc-time (timezone-time-from-absolute date seconds)))
	  (and utc-time
	       (let ((zone (current-time-zone utc-time)))
		 (and (car zone) zone))))))

(defun timezone-fix-time (date local timezone)
  "Convert DATE (default timezone LOCAL) to YYYY-MM-DD-HH-MM-SS-ZONE vector.
If LOCAL is nil, it is assumed to be GMT.
If TIMEZONE is nil, use the local time zone."
  (let* ((date   (timezone-parse-date date))
	 (year   (string-to-int (aref date 0)))
	 (year	 (if (< year 100) (+ year 1900) year))
	 (month  (string-to-int (aref date 1)))
	 (day    (string-to-int (aref date 2)))
	 (time   (timezone-parse-time (aref date 3)))
	 (hour   (string-to-int (aref time 0)))
	 (minute (string-to-int (aref time 1)))
	 (second (string-to-int (aref time 2)))
	 (local  (or (aref date 4) local)) ;Use original if defined
	 (timezone
	  (or timezone
	      (timezone-time-zone-from-absolute
	       (timezone-absolute-from-gregorian month day year)
	       (+ second (* 60 (+ minute (* 60 hour)))))))
	 (diff   (- (timezone-zone-to-minute timezone)
		    (timezone-zone-to-minute local)))
	 (minute (+ minute diff))
	 (hour-fix (floor minute 60)))
    (setq hour (+ hour hour-fix))
    (setq minute (- minute (* 60 hour-fix)))
    ;; HOUR may be larger than 24 or smaller than 0.
    (cond ((<= 24 hour)			;24 -> 00
	   (setq hour (- hour 24))
	   (setq day  (1+ day))
	   (if (< (timezone-last-day-of-month month year) day)
	       (progn
		 (setq month (1+ month))
		 (setq day 1)
		 (if (< 12 month)
		     (progn
		       (setq month 1)
		       (setq year (1+ year))
		       ))
		 )))
	  ((> 0 hour)
	   (setq hour (+ hour 24))
	   (setq day  (1- day))
	   (if (> 1 day)
	       (progn
		 (setq month (1- month))
		 (if (> 1 month)
		     (progn
		       (setq month 12)
		       (setq year (1- year))
		       ))
		 (setq day (timezone-last-day-of-month month year))
		 )))
	  )
    (vector year month day hour minute second timezone)))

;; Partly copied from Calendar program by Edward M. Reingold.
;; Thanks a lot.

(defun timezone-last-day-of-month (month year)
  "The last day in MONTH during YEAR."
  (if (and (= month 2) (timezone-leap-year-p year))
      29
    (aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month))))

(defun timezone-leap-year-p (year)
  "Returns t if YEAR is a Gregorian leap year."
  (or (and (zerop  (% year 4))
	   (not (zerop (% year 100))))
      (zerop (% year 400))))

(defun timezone-day-number (month day year)
  "Return the day number within the year of the date month/day/year."
  (let ((day-of-year (+ day (* 31 (1- month)))))
    (if (> month 2)
	(progn
	  (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
	  (if (timezone-leap-year-p year)
	      (setq day-of-year (1+ day-of-year)))))
    day-of-year))

(defun timezone-absolute-from-gregorian (month day year)
  "The number of days between the Gregorian date 12/31/1 BC and month/day/year.
The Gregorian date Sunday, December 31, 1 BC is imaginary."
  (+ (timezone-day-number month day year);; Days this year
     (* 365 (1- year));;	+ Days in prior years
     (/ (1- year) 4);;		+ Julian leap years
     (- (/ (1- year) 100));;	- century years
     (/ (1- year) 400)));;	+ Gregorian leap years

;;; timezone.el ends here
Commit	Line	Data
a47a5be5 RS	1	;;; Timezone package for GNU Emacs
a47a5be5 RS	2
aa56d805 RS	3	;; Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
	4
	5	;;; Author: Masanobu Umeda
	6	;;; Maintainer: umerin@mse.kyutech.ac.jp
8c54a3ce	7	;;; Keywords: news
a47a5be5 RS	8
	9	;; This file is part of GNU Emacs.
	10
	11	;; GNU Emacs is free software; you can redistribute it and/or modify
	12	;; it under the terms of the GNU General Public License as published by
	13	;; the Free Software Foundation; either version 2, or (at your option)
	14	;; any later version.
	15
	16	;; GNU Emacs is distributed in the hope that it will be useful,
	17	;; but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	19	;; GNU General Public License for more details.
	20
	21	;; You should have received a copy of the GNU General Public License
	22	;; along with GNU Emacs; see the file COPYING. If not, write to
	23	;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
	24
	25	;;; Code:
	26
	27	(provide 'timezone)
	28
	29	(defvar timezone-world-timezones
	30	'(("PST" . -800)
	31	("PDT" . -700)
	32	("MST" . -700)
	33	("MDT" . -600)
	34	("CST" . -600)
	35	("CDT" . -500)
	36	("EST" . -500)
	37	("EDT" . -400)
	38	("AST" . -400) ;by <clamen@CS.CMU.EDU>
	39	("NST" . -330) ;by <clamen@CS.CMU.EDU>
dbc6c26a	40	("UT" . +000)
a47a5be5 RS	41	("GMT" . +000)
	42	("BST" . +100)
	43	("MET" . +100)
	44	("EET" . +200)
	45	("JST" . +900)
	46	("GMT+1" . +100) ("GMT+2" . +200) ("GMT+3" . +300)
	47	("GMT+4" . +400) ("GMT+5" . +500) ("GMT+6" . +600)
	48	("GMT+7" . +700) ("GMT+8" . +800) ("GMT+9" . +900)
	49	("GMT+10" . +1000) ("GMT+11" . +1100) ("GMT+12" . +1200) ("GMT+13" . +1300)
	50	("GMT-1" . -100) ("GMT-2" . -200) ("GMT-3" . -300)
	51	("GMT-4" . -400) ("GMT-5" . -500) ("GMT-6" . -600)
	52	("GMT-7" . -700) ("GMT-8" . -800) ("GMT-9" . -900)
	53	("GMT-10" . -1000) ("GMT-11" . -1100) ("GMT-12" . -1200))
d51c3cda RS	54	"*Time differentials of timezone from GMT in +-HHMM form.
	55	This list is obsolescent, and is present only for backwards compatibility,
	56	because time zone names are ambiguous in practice.
	57	Use `current-time-zone' instead.")
a47a5be5 RS	58
	59	(defvar timezone-months-assoc
	60	'(("JAN" . 1)("FEB" . 2)("MAR" . 3)
	61	("APR" . 4)("MAY" . 5)("JUN" . 6)
	62	("JUL" . 7)("AUG" . 8)("SEP" . 9)
	63	("OCT" . 10)("NOV" . 11)("DEC" . 12))
	64	"Alist of first three letters of a month and its numerical representation.")
	65
	66	(defun timezone-make-date-arpa-standard (date &optional local timezone)
	67	"Convert DATE to an arpanet standard date.
d51c3cda RS	68	Optional 1st argument LOCAL specifies the default local timezone of the DATE;
	69	if nil, GMT is assumed.
	70	Optional 2nd argument TIMEZONE specifies a time zone to be represented in;
	71	if nil, the local time zone is assumed."
	72	(let ((new (timezone-fix-time date local timezone)))
a47a5be5 RS	73	(timezone-make-arpa-date (aref new 0) (aref new 1) (aref new 2)
	74	(timezone-make-time-string
	75	(aref new 3) (aref new 4) (aref new 5))
d51c3cda	76	(aref new 6))
a47a5be5 RS	77	))
	78
	79	(defun timezone-make-date-sortable (date &optional local timezone)
	80	"Convert DATE to a sortable date string.
d51c3cda RS	81	Optional 1st argument LOCAL specifies the default local timezone of the DATE;
	82	if nil, GMT is assumed.
	83	Optional 2nd argument TIMEZONE specifies a timezone to be represented in;
	84	if nil, the local time zone is assumed."
	85	(let ((new (timezone-fix-time date local timezone)))
a47a5be5 RS	86	(timezone-make-sortable-date (aref new 0) (aref new 1) (aref new 2)
	87	(timezone-make-time-string
	88	(aref new 3) (aref new 4) (aref new 5)))
	89	))
	90
	91	\f
	92	;;
	93	;; Parsers and Constructors of Date and Time
	94	;;
	95
	96	(defun timezone-make-arpa-date (year month day time &optional timezone)
	97	"Make arpanet standard date string from YEAR, MONTH, DAY, and TIME.
	98	Optional argument TIMEZONE specifies a time zone."
d51c3cda RS	99	(let ((zone
	100	(if (listp timezone)
	101	(let* ((m (timezone-zone-to-minute timezone))
	102	(absm (if (< m 0) (- m) m)))
	103	(format "%c%02d%02d"
	104	(if (< m 0) ?- ?+) (/ absm 60) (% absm 60)))
	105	timezone)))
	106	(format "%02d %s %04d %s %s"
	107	day
	108	(capitalize (car (rassq month timezone-months-assoc)))
	109	year
	110	time
	111	zone)))
a47a5be5 RS	112
	113	(defun timezone-make-sortable-date (year month day time)
	114	"Make sortable date string from YEAR, MONTH, DAY, and TIME."
	115	(format "%4d%02d%02d%s"
d51c3cda	116	year month day time))
a47a5be5 RS	117
	118	(defun timezone-make-time-string (hour minute second)
	119	"Make time string from HOUR, MINUTE, and SECOND."
	120	(format "%02d:%02d:%02d" hour minute second))
	121
	122	(defun timezone-parse-date (date)
6b77e539 RS	123	"Parse DATE and return a vector [YEAR MONTH DAY TIME TIMEZONE].
	124	19 is prepended to year if necessary. Timezone may be nil if nothing.
	125	Understands the following styles:
a47a5be5 RS	126	(1) 14 Apr 89 03:20[:12] [GMT]
	127	(2) Fri, 17 Mar 89 4:01[:33] [GMT]
	128	(3) Mon Jan 16 16:12[:37] [GMT] 1989
6b77e539	129	(4) 6 May 1992 1641-JST (Wednesday)
2f9a1ee2 RS	130	(5) 22-AUG-1993 10:59:12.82
	131	(6) Thu, 11 Apr 16:17:12 91 [MET]
	132	(7) Mon, 6 Jul 16:47:20 T 1992 [MET]"
a47a5be5 RS	133	(let ((date (or date ""))
	134	(year nil)
	135	(month nil)
	136	(day nil)
	137	(time nil)
	138	(zone nil)) ;This may be nil.
	139	(cond ((string-match
2f9a1ee2 RS	140	"\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\\|\\)\\([0-9]+\\)[ \t]*\\'" date)
	141	;; Styles: (6) and (7) without timezone
	142	(setq year 6 month 3 day 2 time 4 zone nil))
	143	((string-match
	144	"\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\\|\\)\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	145	;; Styles: (6) and (7) with timezone and buggy timezone
	146	(setq year 6 month 3 day 2 time 4 zone 7))
	147	((string-match
a47a5be5 RS	148	"\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\'" date)
	149	;; Styles: (1) and (2) without timezone
	150	(setq year 3 month 2 day 1 time 4 zone nil))
	151	((string-match
	152	"\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	153	;; Styles: (1) and (2) with timezone and buggy timezone
	154	(setq year 3 month 2 day 1 time 4 zone 5))
	155	((string-match
	156	"\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([0-9]+\\)" date)
	157	;; Styles: (3) without timezone
	158	(setq year 4 month 1 day 2 time 3 zone nil))
	159	((string-match
	160	"\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)[ \t]+\\([0-9]+\\)" date)
6b77e539	161	;; Styles: (3) with timezone
a47a5be5 RS	162	(setq year 5 month 1 day 2 time 3 zone 4))
	163	((string-match
	164	"\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
	165	;; Styles: (4) with timezone
	166	(setq year 3 month 2 day 1 time 4 zone 5))
6b77e539 RS	167	((string-match
	168	"\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\.[0-9]+" date)
	169	;; Styles: (5) without timezone.
	170	(setq year 3 month 2 day 1 time 4 zone nil))
a47a5be5 RS	171	)
	172	(if year
	173	(progn
	174	(setq year
	175	(substring date (match-beginning year) (match-end year)))
	176	;; It is now Dec 1992. 8 years before the end of the World.
	177	(if (< (length year) 4)
	178	(setq year (concat "19" (substring year -2 nil))))
	179	(setq month
	180	(int-to-string
	181	(cdr
	182	(assoc
	183	(upcase
	184	;; Don't use `match-end' in order to take 3
	185	;; letters from the beginning.
	186	(substring date
	187	(match-beginning month)
	188	(+ (match-beginning month) 3)))
	189	timezone-months-assoc))))
	190	(setq day
	191	(substring date (match-beginning day) (match-end day)))
	192	(setq time
	193	(substring date (match-beginning time) (match-end time)))))
	194	(if zone
	195	(setq zone
	196	(substring date (match-beginning zone) (match-end zone))))
	197	;; Return a vector.
	198	(if year
	199	(vector year month day time zone)
	200	(vector "0" "0" "0" "0" nil))
	201	))
	202
	203	(defun timezone-parse-time (time)
	204	"Parse TIME (HH:MM:SS) and return a vector [hour minute second].
	205	Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
	206	(let ((time (or time ""))
	207	(hour nil)
	208	(minute nil)
	209	(second nil))
	210	(cond ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)\\'" time)
	211	;; HH:MM:SS
	212	(setq hour 1 minute 2 second 3))
	213	((string-match "\\`\\([0-9]+\\):\\([0-9]+\\)\\'" time)
	214	;; HH:MM
	215	(setq hour 1 minute 2 second nil))
	216	((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
	217	;; HHMMSS
	218	(setq hour 1 minute 2 second 3))
	219	((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
	220	;; HHMM
	221	(setq hour 1 minute 2 second nil))
	222	)
	223	;; Return [hour minute second]
	224	(vector
	225	(if hour
	226	(substring time (match-beginning hour) (match-end hour)) "0")
	227	(if minute
	228	(substring time (match-beginning minute) (match-end minute)) "0")
	229	(if second
	230	(substring time (match-beginning second) (match-end second)) "0"))
	231	))
	232
	233	\f
	234	;; Miscellaneous
235
236	(defun timezone-zone-to-minute (timezone)
d51c3cda RS	237	"Translate TIMEZONE to an integer minute offset from GMT.
	238	TIMEZONE can be a cons cell containing the output of current-time-zone,
	239	or an integer of the form +-HHMM, or a time zone name."
	240	(cond
	241	((consp timezone)
	242	(/ (car timezone) 60))
	243	(timezone
a47a5be5 RS	244	(progn
	245	(setq timezone
	246	(or (cdr (assoc (upcase timezone) timezone-world-timezones))
	247	;; +900
	248	timezone))
	249	(if (stringp timezone)
	250	(setq timezone (string-to-int timezone)))
	251	;; Taking account of minute in timezone.
	252	;; HHMM -> MM
9b1868cc	253	(let* ((abszone (abs timezone))
a47a5be5	254	(minutes (+ (* 60 (/ abszone 100)) (% abszone 100))))
d51c3cda RS	255	(if (< timezone 0) (- minutes) minutes))))
	256	(t 0)))
	257
	258	(defun timezone-time-from-absolute (date seconds)
	259	"Compute the UTC time equivalent to DATE at time SECONDS after midnight.
	260	Return a list suitable as an argument to current-time-zone,
	261	or nil if the date cannot be thus represented.
	262	DATE is the number of days elapsed since the (imaginary)
	263	Gregorian date Sunday, December 31, 1 BC."
	264	(let* ((current-time-origin 719162)
	265	;; (timezone-absolute-from-gregorian 1 1 1970)
	266	(days (- date current-time-origin))
	267	(seconds-per-day (float 86400))
	268	(seconds (+ seconds (* days seconds-per-day)))
	269	(current-time-arithmetic-base (float 65536))
	270	(hi (floor (/ seconds current-time-arithmetic-base)))
	271	(hibase (* hi current-time-arithmetic-base))
	272	(lo (floor (- seconds hibase))))
	273	(and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow.
	274	(cons hi lo))))
a47a5be5	275
d51c3cda RS	276	(defun timezone-time-zone-from-absolute (date seconds)
	277	"Compute the local time zone for DATE at time SECONDS after midnight.
	278	Return a list in the same format as current-time-zone's result,
	279	or nil if the local time zone could not be computed.
	280	DATE is the number of days elapsed since the (imaginary)
	281	Gregorian date Sunday, December 31, 1 BC."
	282	(and (fboundp 'current-time-zone)
	283	(let ((utc-time (timezone-time-from-absolute date seconds)))
	284	(and utc-time
	285	(let ((zone (current-time-zone utc-time)))
	286	(and (car zone) zone))))))
	287
	288	(defun timezone-fix-time (date local timezone)
dce33aad	289	"Convert DATE (default timezone LOCAL) to YYYY-MM-DD-HH-MM-SS-ZONE vector.
d51c3cda RS	290	If LOCAL is nil, it is assumed to be GMT.
	291	If TIMEZONE is nil, use the local time zone."
	292	(let* ((date (timezone-parse-date date))
	293	(year (string-to-int (aref date 0)))
	294	(year (if (< year 100) (+ year 1900) year))
	295	(month (string-to-int (aref date 1)))
	296	(day (string-to-int (aref date 2)))
	297	(time (timezone-parse-time (aref date 3)))
	298	(hour (string-to-int (aref time 0)))
	299	(minute (string-to-int (aref time 1)))
	300	(second (string-to-int (aref time 2)))
	301	(local (or (aref date 4) local)) ;Use original if defined
	302	(timezone
	303	(or timezone
	304	(timezone-time-zone-from-absolute
	305	(timezone-absolute-from-gregorian month day year)
	306	(+ second (* 60 (+ minute (* 60 hour)))))))
	307	(diff (- (timezone-zone-to-minute timezone)
	308	(timezone-zone-to-minute local)))
	309	(minute (+ minute diff))
9b1868cc	310	(hour-fix (floor minute 60)))
a47a5be5	311	(setq hour (+ hour hour-fix))
d51c3cda RS	312	(setq minute (- minute (* 60 hour-fix)))
	313	;; HOUR may be larger than 24 or smaller than 0.
	314	(cond ((<= 24 hour) ;24 -> 00
	315	(setq hour (- hour 24))
	316	(setq day (1+ day))
	317	(if (< (timezone-last-day-of-month month year) day)
	318	(progn
	319	(setq month (1+ month))
	320	(setq day 1)
	321	(if (< 12 month)
	322	(progn
	323	(setq month 1)
	324	(setq year (1+ year))
	325	))
	326	)))
	327	((> 0 hour)
	328	(setq hour (+ hour 24))
	329	(setq day (1- day))
	330	(if (> 1 day)
	331	(progn
	332	(setq month (1- month))
	333	(if (> 1 month)
	334	(progn
	335	(setq month 12)
	336	(setq year (1- year))
	337	))
	338	(setq day (timezone-last-day-of-month month year))
	339	)))
	340	)
	341	(vector year month day hour minute second timezone)))
a47a5be5 RS	342
	343	;; Partly copied from Calendar program by Edward M. Reingold.
	344	;; Thanks a lot.
	345
	346	(defun timezone-last-day-of-month (month year)
	347	"The last day in MONTH during YEAR."
	348	(if (and (= month 2) (timezone-leap-year-p year))
	349	29
	350	(aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month))))
	351
	352	(defun timezone-leap-year-p (year)
	353	"Returns t if YEAR is a Gregorian leap year."
	354	(or (and (zerop (% year 4))
	355	(not (zerop (% year 100))))
	356	(zerop (% year 400))))
aa56d805	357
d51c3cda RS	358	(defun timezone-day-number (month day year)
	359	"Return the day number within the year of the date month/day/year."
	360	(let ((day-of-year (+ day (* 31 (1- month)))))
	361	(if (> month 2)
	362	(progn
	363	(setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
	364	(if (timezone-leap-year-p year)
	365	(setq day-of-year (1+ day-of-year)))))
	366	day-of-year))
	367
	368	(defun timezone-absolute-from-gregorian (month day year)
	369	"The number of days between the Gregorian date 12/31/1 BC and month/day/year.
	370	The Gregorian date Sunday, December 31, 1 BC is imaginary."
	371	(+ (timezone-day-number month day year);; Days this year
	372	(* 365 (1- year));; + Days in prior years
	373	(/ (1- year) 4);; + Julian leap years
	374	(- (/ (1- year) 100));; - century years
	375	(/ (1- year) 400)));; + Gregorian leap years
	376
aa56d805	377	;;; timezone.el ends here