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1 ;;; timezone.el --- time zone package for GNU Emacs
3 ;; Copyright (C) 1990, 1991, 1992, 1993, 1996, 1999, 2002, 2003,
4 ;; 2004, 2005 Free Software Foundation, Inc.
6 ;; Author: Masanobu Umeda
7 ;; Maintainer: umerin@mse.kyutech.ac.jp
8 ;; Keywords: news
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software; you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25 ;; Boston, MA 02110-1301, USA.
27 ;;; Commentary:
29 ;;; Code:
31 (defvar timezone-world-timezones
32 '(("PST" . -800)
33 ("PDT" . -700)
34 ("MST" . -700)
35 ("MDT" . -600)
36 ("CST" . -600)
37 ("CDT" . -500)
38 ("EST" . -500)
39 ("EDT" . -400)
40 ("AST" . -400) ;by <clamen@CS.CMU.EDU>
41 ("NST" . -330) ;by <clamen@CS.CMU.EDU>
42 ("UT" . +000)
43 ("GMT" . +000)
44 ("BST" . +100)
45 ("MET" . +100)
46 ("EET" . +200)
47 ("JST" . +900)
48 ("GMT+1" . +100) ("GMT+2" . +200) ("GMT+3" . +300)
49 ("GMT+4" . +400) ("GMT+5" . +500) ("GMT+6" . +600)
50 ("GMT+7" . +700) ("GMT+8" . +800) ("GMT+9" . +900)
51 ("GMT+10" . +1000) ("GMT+11" . +1100) ("GMT+12" . +1200) ("GMT+13" . +1300)
52 ("GMT-1" . -100) ("GMT-2" . -200) ("GMT-3" . -300)
53 ("GMT-4" . -400) ("GMT-5" . -500) ("GMT-6" . -600)
54 ("GMT-7" . -700) ("GMT-8" . -800) ("GMT-9" . -900)
55 ("GMT-10" . -1000) ("GMT-11" . -1100) ("GMT-12" . -1200))
56 "*Time differentials of timezone from GMT in +-HHMM form.
57 This list is obsolescent, and is present only for backwards compatibility,
58 because time zone names are ambiguous in practice.
59 Use `current-time-zone' instead.")
61 (defvar timezone-months-assoc
62 '(("JAN" . 1)("FEB" . 2)("MAR" . 3)
63 ("APR" . 4)("MAY" . 5)("JUN" . 6)
64 ("JUL" . 7)("AUG" . 8)("SEP" . 9)
65 ("OCT" . 10)("NOV" . 11)("DEC" . 12))
66 "Alist of first three letters of a month and its numerical representation.")
68 (defun timezone-make-date-arpa-standard (date &optional local timezone)
69 "Convert DATE to an arpanet standard date.
70 Optional 2nd argument LOCAL specifies the default local timezone of the DATE;
71 if nil, GMT is assumed.
72 Optional 3rd argument TIMEZONE specifies a time zone to be represented in;
73 if nil, the local time zone is assumed."
74 (let ((new (timezone-fix-time date local timezone)))
75 (timezone-make-arpa-date (aref new 0) (aref new 1) (aref new 2)
76 (timezone-make-time-string
77 (aref new 3) (aref new 4) (aref new 5))
78 (aref new 6))
81 (defun timezone-make-date-sortable (date &optional local timezone)
82 "Convert DATE to a sortable date string.
83 Optional 2nd argument LOCAL specifies the default local timezone of the DATE;
84 if nil, GMT is assumed.
85 Optional 3rd argument TIMEZONE specifies a timezone to be represented in;
86 if nil, the local time zone is assumed."
87 (let ((new (timezone-fix-time date local timezone)))
88 (timezone-make-sortable-date (aref new 0) (aref new 1) (aref new 2)
89 (timezone-make-time-string
90 (aref new 3) (aref new 4) (aref new 5)))
95 ;; Parsers and Constructors of Date and Time
98 (defun timezone-make-arpa-date (year month day time &optional timezone)
99 "Make arpanet standard date string from YEAR, MONTH, DAY, and TIME.
100 Optional argument TIMEZONE specifies a time zone."
101 (let ((zone
102 (if (listp timezone)
103 (let* ((m (timezone-zone-to-minute timezone))
104 (absm (if (< m 0) (- m) m)))
105 (format "%c%02d%02d"
106 (if (< m 0) ?- ?+) (/ absm 60) (% absm 60)))
107 timezone)))
108 (format "%02d %s %04d %s %s"
110 (capitalize (car (rassq month timezone-months-assoc)))
111 year
112 time
113 zone)))
115 (defun timezone-make-sortable-date (year month day time)
116 "Make sortable date string from YEAR, MONTH, DAY, and TIME."
117 (format "%4d%02d%02d%s"
118 year month day time))
120 (defun timezone-make-time-string (hour minute second)
121 "Make time string from HOUR, MINUTE, and SECOND."
122 (format "%02d:%02d:%02d" hour minute second))
124 (defun timezone-parse-date (date)
125 "Parse DATE and return a vector [YEAR MONTH DAY TIME TIMEZONE].
126 Two-digit dates are `windowed'. Those <69 have 2000 added; otherwise 1900
127 is added. Three-digit dates have 1900 added.
128 TIMEZONE is nil for DATEs without a zone field.
130 Understands the following styles:
131 (1) 14 Apr 89 03:20[:12] [GMT]
132 (2) Fri, 17 Mar 89 4:01[:33] [GMT]
133 (3) Mon Jan 16 16:12[:37] [GMT] 1989
134 (4) 6 May 1992 1641-JST (Wednesday)
135 (5) 22-AUG-1993 10:59:12.82
136 (6) Thu, 11 Apr 16:17:12 91 [MET]
137 (7) Mon, 6 Jul 16:47:20 T 1992 [MET]
138 (8) 1996-06-24 21:13:12 [GMT]
139 (9) 1996-06-24 21:13-ZONE"
140 ;; Get rid of any text properties.
141 (and (stringp date)
142 (or (text-properties-at 0 date)
143 (next-property-change 0 date))
144 (setq date (copy-sequence date))
145 (set-text-properties 0 (length date) nil date))
146 (let ((date (or date ""))
147 (year nil)
148 (month nil)
149 (day nil)
150 (time nil)
151 (zone nil)) ;This may be nil.
152 (cond ((string-match
153 "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)" date)
154 ;; Styles: (1) and (2) with timezone and buggy timezone
155 ;; This is most common in mail and news,
156 ;; so it is worth trying first.
157 (setq year 3 month 2 day 1 time 4 zone 5))
158 ((string-match
159 "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\'" date)
160 ;; Styles: (1) and (2) without timezone
161 (setq year 3 month 2 day 1 time 4 zone nil))
162 ((string-match
163 "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\'" date)
164 ;; Styles: (6) and (7) without timezone
165 (setq year 6 month 3 day 2 time 4 zone nil))
166 ((string-match
167 "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
168 ;; Styles: (6) and (7) with timezone and buggy timezone
169 (setq year 6 month 3 day 2 time 4 zone 7))
170 ((string-match
171 "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([0-9]+\\)" date)
172 ;; Styles: (3) without timezone
173 (setq year 4 month 1 day 2 time 3 zone nil))
174 ((string-match
175 "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)[ \t]+\\([0-9]+\\)" date)
176 ;; Styles: (3) with timezone
177 (setq year 5 month 1 day 2 time 3 zone 4))
178 ((string-match
179 "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
180 ;; Styles: (4) with timezone
181 (setq year 3 month 2 day 1 time 4 zone 5))
182 ((string-match
183 "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\(\\.[0-9]+\\)?[ \t]+\\([-+a-zA-Z0-9]+\\)" date)
184 ;; Styles: (5) with timezone.
185 (setq year 3 month 2 day 1 time 4 zone 6))
186 ((string-match
187 "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\(\\.[0-9]+\\)?" date)
188 ;; Styles: (5) without timezone.
189 (setq year 3 month 2 day 1 time 4 zone nil))
190 ((string-match
191 "\\([0-9]+\\)-\\([0-9]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)" date)
192 ;; Styles: (8) with timezone.
193 (setq year 1 month 2 day 3 time 4 zone 5))
194 ((string-match
195 "\\([0-9]+\\)-\\([0-9]+\\)-\\([0-9]+\\)[T \t]+\\([0-9]+:[0-9]+\\)[ \t]+\\([-+a-zA-Z0-9:]+\\)" date)
196 ;; Styles: (8) with timezone with a colon in it.
197 (setq year 1 month 2 day 3 time 4 zone 5))
198 ((string-match
199 "\\([0-9]+\\)-\\([0-9]+\\)-\\([0-9]+\\)[T \t]+\\([0-9]+:[0-9]+:[0-9]+\\)" date)
200 ;; Styles: (8) without timezone.
201 (setq year 1 month 2 day 3 time 4 zone nil))
203 (when year
204 (setq year (match-string year date))
205 ;; Guess ambiguous years. Assume years < 69 don't predate the
206 ;; Unix Epoch, so are 2000+. Three-digit years are assumed to
207 ;; be relative to 1900.
208 (if (< (length year) 4)
209 (let ((y (string-to-number year)))
210 (if (< y 69)
211 (setq y (+ y 100)))
212 (setq year (int-to-string (+ 1900 y)))))
213 (setq month
214 (if (= (aref date (+ (match-beginning month) 2)) ?-)
215 ;; Handle numeric months, spanning exactly two digits.
216 (substring date
217 (match-beginning month)
218 (+ (match-beginning month) 2))
219 (let* ((string (substring date
220 (match-beginning month)
221 (+ (match-beginning month) 3)))
222 (monthnum
223 (cdr (assoc (upcase string) timezone-months-assoc))))
224 (if monthnum
225 (int-to-string monthnum)))))
226 (setq day (match-string day date))
227 (setq time (match-string time date)))
228 (if zone (setq zone (match-string zone date)))
229 ;; Return a vector.
230 (if (and year month)
231 (vector year month day time zone)
232 (vector "0" "0" "0" "0" nil))))
234 (defun timezone-parse-time (time)
235 "Parse TIME (HH:MM:SS) and return a vector [hour minute second].
236 Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
237 (let ((time (or time ""))
238 hour minute second)
239 (cond ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)\\'" time)
240 ;; HH:MM:SS
241 (setq hour 1 minute 2 second 3))
242 ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\)\\'" time)
243 ;; HH:MM
244 (setq hour 1 minute 2 second nil))
245 ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
246 ;; HHMMSS
247 (setq hour 1 minute 2 second 3))
248 ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
249 ;; HHMM
250 (setq hour 1 minute 2 second nil))
252 ;; Return [hour minute second]
253 (vector
254 (if hour (match-string hour time) "0")
255 (if minute (match-string minute time) "0")
256 (if second (match-string second time) "0"))))
259 ;; Miscellaneous
261 (defun timezone-zone-to-minute (timezone)
262 "Translate TIMEZONE to an integer minute offset from GMT.
263 TIMEZONE can be a cons cell containing the output of current-time-zone,
264 or an integer of the form +-HHMM, or a time zone name."
265 (cond
266 ((consp timezone)
267 (/ (car timezone) 60))
268 (timezone
269 (progn
270 (setq timezone
271 (or (cdr (assoc (upcase timezone) timezone-world-timezones))
272 ;; +900
273 timezone))
274 (if (stringp timezone)
275 (setq timezone (string-to-number timezone)))
276 ;; Taking account of minute in timezone.
277 ;; HHMM -> MM
278 (let* ((abszone (abs timezone))
279 (minutes (+ (* 60 (/ abszone 100)) (% abszone 100))))
280 (if (< timezone 0) (- minutes) minutes))))
281 (t 0)))
283 (defun timezone-time-from-absolute (date seconds)
284 "Compute the UTC time equivalent to DATE at time SECONDS after midnight.
285 Return a list suitable as an argument to current-time-zone,
286 or nil if the date cannot be thus represented.
287 DATE is the number of days elapsed since the (imaginary)
288 Gregorian date Sunday, December 31, 1 BC."
289 (let* ((current-time-origin 719163)
290 ;; (timezone-absolute-from-gregorian 1 1 1970)
291 (days (- date current-time-origin))
292 (seconds-per-day (float 86400))
293 (seconds (+ seconds (* days seconds-per-day)))
294 (current-time-arithmetic-base (float 65536))
295 (hi (floor (/ seconds current-time-arithmetic-base)))
296 (hibase (* hi current-time-arithmetic-base))
297 (lo (floor (- seconds hibase))))
298 (and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow.
299 (cons hi lo))))
301 (defun timezone-time-zone-from-absolute (date seconds)
302 "Compute the local time zone for DATE at time SECONDS after midnight.
303 Return a list in the same format as current-time-zone's result,
304 or nil if the local time zone could not be computed.
305 DATE is the number of days elapsed since the (imaginary)
306 Gregorian date Sunday, December 31, 1 BC."
307 (and (fboundp 'current-time-zone)
308 (let ((utc-time (timezone-time-from-absolute date seconds)))
309 (and utc-time
310 (let ((zone (current-time-zone utc-time)))
311 (and (car zone) zone))))))
313 (defun timezone-fix-time (date local timezone)
314 "Convert DATE (default timezone LOCAL) to YYYY-MM-DD-HH-MM-SS-ZONE vector.
315 If LOCAL is nil, it is assumed to be GMT.
316 If TIMEZONE is nil, use the local time zone."
317 (let* ((date (timezone-parse-date date))
318 (year (string-to-number (aref date 0)))
319 (year (cond ((< year 69)
320 (+ year 2000))
321 ((< year 100)
322 (+ year 1900))
323 ((< year 1000) ; possible 3-digit years.
324 (+ year 1900))
325 (t year)))
326 (month (string-to-number (aref date 1)))
327 (day (string-to-number (aref date 2)))
328 (time (timezone-parse-time (aref date 3)))
329 (hour (string-to-number (aref time 0)))
330 (minute (string-to-number (aref time 1)))
331 (second (string-to-number (aref time 2)))
332 (local (or (aref date 4) local)) ;Use original if defined
333 (timezone
334 (or timezone
335 (timezone-time-zone-from-absolute
336 (timezone-absolute-from-gregorian month day year)
337 (+ second (* 60 (+ minute (* 60 hour)))))))
338 (diff (- (timezone-zone-to-minute timezone)
339 (timezone-zone-to-minute local)))
340 (minute (+ minute diff))
341 (hour-fix (floor minute 60)))
342 (setq hour (+ hour hour-fix))
343 (setq minute (- minute (* 60 hour-fix)))
344 ;; HOUR may be larger than 24 or smaller than 0.
345 (cond ((<= 24 hour) ;24 -> 00
346 (setq hour (- hour 24))
347 (setq day (1+ day))
348 (when (< (timezone-last-day-of-month month year) day)
349 (setq month (1+ month))
350 (setq day 1)
351 (when (< 12 month)
352 (setq month 1)
353 (setq year (1+ year)))))
354 ((> 0 hour)
355 (setq hour (+ hour 24))
356 (setq day (1- day))
357 (when (> 1 day)
358 (setq month (1- month))
359 (when (> 1 month)
360 (setq month 12)
361 (setq year (1- year)))
362 (setq day (timezone-last-day-of-month month year)))))
363 (vector year month day hour minute second timezone)))
365 ;; Partly copied from Calendar program by Edward M. Reingold.
366 ;; Thanks a lot.
368 (defun timezone-last-day-of-month (month year)
369 "The last day in MONTH during YEAR."
370 (if (and (= month 2) (timezone-leap-year-p year))
372 (aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month))))
374 (defun timezone-leap-year-p (year)
375 "Returns t if YEAR is a Gregorian leap year."
376 (or (and (zerop (% year 4))
377 (not (zerop (% year 100))))
378 (zerop (% year 400))))
380 (defun timezone-day-number (month day year)
381 "Return the day number within the year of the date month/day/year."
382 (let ((day-of-year (+ day (* 31 (1- month)))))
383 (if (> month 2)
384 (progn
385 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
386 (if (timezone-leap-year-p year)
387 (setq day-of-year (1+ day-of-year)))))
388 day-of-year))
390 (defun timezone-absolute-from-gregorian (month day year)
391 "The number of days between the Gregorian date 12/31/1 BC and month/day/year.
392 The Gregorian date Sunday, December 31, 1 BC is imaginary."
393 (+ (timezone-day-number month day year);; Days this year
394 (* 365 (1- year));; + Days in prior years
395 (/ (1- year) 4);; + Julian leap years
396 (- (/ (1- year) 100));; - century years
397 (/ (1- year) 400)));; + Gregorian leap years
399 (provide 'timezone)
401 ;;; arch-tag: e23d5bc6-f32d-48ba-8996-323e9d654b3f
402 ;;; timezone.el ends here