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be010748 | 1 | ;;; timezone.el --- time zone package for GNU Emacs |
a47a5be5 | 2 | |
acaf905b | 3 | ;; Copyright (C) 1990-1993, 1996, 1999, 2001-2012 |
95df8112 | 4 | ;; Free Software Foundation, Inc. |
aa56d805 | 5 | |
be010748 RS |
6 | ;; Author: Masanobu Umeda |
7 | ;; Maintainer: umerin@mse.kyutech.ac.jp | |
8 | ;; Keywords: news | |
a47a5be5 RS |
9 | |
10 | ;; This file is part of GNU Emacs. | |
11 | ||
eb3fa2cf | 12 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
a47a5be5 | 13 | ;; it under the terms of the GNU General Public License as published by |
eb3fa2cf GM |
14 | ;; the Free Software Foundation, either version 3 of the License, or |
15 | ;; (at your option) any later version. | |
a47a5be5 RS |
16 | |
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. | |
21 | ||
22 | ;; You should have received a copy of the GNU General Public License | |
eb3fa2cf | 23 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
a47a5be5 | 24 | |
e8af40ee PJ |
25 | ;;; Commentary: |
26 | ||
a47a5be5 RS |
27 | ;;; Code: |
28 | ||
a47a5be5 RS |
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. | |
a184d9bf | 68 | Optional 2nd argument LOCAL specifies the default local timezone of the DATE; |
d51c3cda | 69 | if nil, GMT is assumed. |
a184d9bf | 70 | Optional 3rd argument TIMEZONE specifies a time zone to be represented in; |
d51c3cda RS |
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. | |
a184d9bf | 81 | Optional 2nd argument LOCAL specifies the default local timezone of the DATE; |
d51c3cda | 82 | if nil, GMT is assumed. |
a184d9bf | 83 | Optional 3rd argument TIMEZONE specifies a timezone to be represented in; |
d51c3cda RS |
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 | 123 | "Parse DATE and return a vector [YEAR MONTH DAY TIME TIMEZONE]. |
ca87e960 DL |
124 | Two-digit dates are `windowed'. Those <69 have 2000 added; otherwise 1900 |
125 | is added. Three-digit dates have 1900 added. | |
126 | TIMEZONE is nil for DATEs without a zone field. | |
127 | ||
6b77e539 | 128 | Understands the following styles: |
a47a5be5 RS |
129 | (1) 14 Apr 89 03:20[:12] [GMT] |
130 | (2) Fri, 17 Mar 89 4:01[:33] [GMT] | |
131 | (3) Mon Jan 16 16:12[:37] [GMT] 1989 | |
6b77e539 | 132 | (4) 6 May 1992 1641-JST (Wednesday) |
2f9a1ee2 RS |
133 | (5) 22-AUG-1993 10:59:12.82 |
134 | (6) Thu, 11 Apr 16:17:12 91 [MET] | |
9d02faa7 | 135 | (7) Mon, 6 Jul 16:47:20 T 1992 [MET] |
43776ca0 | 136 | (8) 1996-06-24 21:13:12 [GMT] |
b6377f1d MH |
137 | (9) 1996-06-24 21:13-ZONE |
138 | (10) 19960624T211312" | |
139 | ;; Get rid of any text properties. | |
f4573839 RS |
140 | (and (stringp date) |
141 | (or (text-properties-at 0 date) | |
b6377f1d | 142 | (next-property-change 0 date)) |
f4573839 RS |
143 | (setq date (copy-sequence date)) |
144 | (set-text-properties 0 (length date) nil date)) | |
a47a5be5 | 145 | (let ((date (or date "")) |
b6377f1d MH |
146 | (year nil) |
147 | (month nil) | |
148 | (day nil) | |
149 | (time nil) | |
150 | (zone nil)) ;This may be nil. | |
a47a5be5 | 151 | (cond ((string-match |
b6377f1d MH |
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 | ;; This is most common in mail and news, | |
155 | ;; so it is worth trying first. | |
156 | (setq year 3 month 2 day 1 time 4 zone 5)) | |
157 | ((string-match | |
158 | "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\'" date) | |
159 | ;; Styles: (1) and (2) without timezone | |
160 | (setq year 3 month 2 day 1 time 4 zone nil)) | |
161 | ((string-match | |
162 | "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\'" date) | |
163 | ;; Styles: (6) and (7) without timezone | |
164 | (setq year 6 month 3 day 2 time 4 zone nil)) | |
165 | ((string-match | |
166 | "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date) | |
167 | ;; Styles: (6) and (7) with timezone and buggy timezone | |
168 | (setq year 6 month 3 day 2 time 4 zone 7)) | |
169 | ((string-match | |
170 | "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([0-9]+\\)" date) | |
171 | ;; Styles: (3) without timezone | |
172 | (setq year 4 month 1 day 2 time 3 zone nil)) | |
173 | ((string-match | |
174 | "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)[ \t]+\\([0-9]+\\)" date) | |
175 | ;; Styles: (3) with timezone | |
176 | (setq year 5 month 1 day 2 time 3 zone 4)) | |
177 | ((string-match | |
178 | "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date) | |
179 | ;; Styles: (4) with timezone | |
180 | (setq year 3 month 2 day 1 time 4 zone 5)) | |
181 | ((string-match | |
182 | "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\(\\.[0-9]+\\)?[ \t]+\\([-+a-zA-Z0-9]+\\)" date) | |
183 | ;; Styles: (5) with timezone. | |
184 | (setq year 3 month 2 day 1 time 4 zone 6)) | |
185 | ((string-match | |
186 | "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\(\\.[0-9]+\\)?" date) | |
187 | ;; Styles: (5) without timezone. | |
188 | (setq year 3 month 2 day 1 time 4 zone nil)) | |
189 | ((string-match | |
190 | "\\([0-9]+\\)-\\([0-9]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)" date) | |
191 | ;; Styles: (8) with timezone. | |
192 | (setq year 1 month 2 day 3 time 4 zone 5)) | |
193 | ((string-match | |
194 | "\\([0-9]\\{4\\}\\)-?\\([0-9]\\{0,2\\}\\)-?\\([0-9]\\{0,2\\}\\)[T \t]+\\([0-9]\\{0,2\\}:?[0-9]\\{0,2\\}:?[0-9]\\{0,2\\}\\)[ \t]*\\([-+a-zA-Z]+[0-9:]*\\)" date) | |
195 | ;; Styles: (8) with timezone with a colon in it. | |
196 | (setq year 1 month 2 day 3 time 4 zone 5)) | |
197 | ((string-match | |
198 | "\\([0-9]\\{4\\}\\)-?\\([0-9]\\{0,2\\}\\)-?\\([0-9]\\{0,2\\}\\)[T \t]+\\([0-9]+:?[0-9]+:?[0-9]+\\)" date) | |
199 | ;; Styles: (8) without timezone. | |
200 | (setq year 1 month 2 day 3 time 4 zone nil)) | |
201 | ) | |
202 | ||
64606d07 DL |
203 | (when year |
204 | (setq year (match-string year date)) | |
162100b5 | 205 | ;; Guess ambiguous years. Assume years < 69 don't predate the |
d1912872 DL |
206 | ;; Unix Epoch, so are 2000+. Three-digit years are assumed to |
207 | ;; be relative to 1900. | |
b6377f1d MH |
208 | (when (< (length year) 4) |
209 | (let ((y (string-to-number year))) | |
210 | (when (< y 69) | |
211 | (setq y (+ y 100))) | |
212 | (setq year (int-to-string (+ 1900 y))))) | |
64606d07 | 213 | (setq month |
b6377f1d MH |
214 | (if (or (= (aref date (+ (match-beginning month) 2)) ?-) |
215 | (let ((n (string-to-number | |
216 | (char-to-string | |
217 | (aref date (+ (match-beginning month) 2)))))) | |
218 | (= (aref (number-to-string n) 0) | |
219 | (aref date (+ (match-beginning month) 2))))) | |
220 | ;; Handle numeric months, spanning exactly two digits. | |
221 | (substring date | |
222 | (match-beginning month) | |
223 | (+ (match-beginning month) 2)) | |
224 | (let* ((string (substring date | |
225 | (match-beginning month) | |
226 | (+ (match-beginning month) 3))) | |
227 | (monthnum | |
228 | (cdr (assoc (upcase string) timezone-months-assoc)))) | |
229 | (when monthnum | |
230 | (int-to-string monthnum))))) | |
64606d07 DL |
231 | (setq day (match-string day date)) |
232 | (setq time (match-string time date))) | |
b6377f1d | 233 | (when zone (setq zone (match-string zone date))) |
a47a5be5 | 234 | ;; Return a vector. |
dd713b75 | 235 | (if (and year month) |
b6377f1d | 236 | (vector year month day time zone) |
64606d07 | 237 | (vector "0" "0" "0" "0" nil)))) |
a47a5be5 RS |
238 | |
239 | (defun timezone-parse-time (time) | |
240 | "Parse TIME (HH:MM:SS) and return a vector [hour minute second]. | |
241 | Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM." | |
242 | (let ((time (or time "")) | |
64606d07 | 243 | hour minute second) |
a47a5be5 RS |
244 | (cond ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)\\'" time) |
245 | ;; HH:MM:SS | |
246 | (setq hour 1 minute 2 second 3)) | |
247 | ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\)\\'" time) | |
248 | ;; HH:MM | |
249 | (setq hour 1 minute 2 second nil)) | |
250 | ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time) | |
251 | ;; HHMMSS | |
252 | (setq hour 1 minute 2 second 3)) | |
253 | ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time) | |
254 | ;; HHMM | |
255 | (setq hour 1 minute 2 second nil)) | |
256 | ) | |
257 | ;; Return [hour minute second] | |
258 | (vector | |
64606d07 DL |
259 | (if hour (match-string hour time) "0") |
260 | (if minute (match-string minute time) "0") | |
261 | (if second (match-string second time) "0")))) | |
a47a5be5 RS |
262 | |
263 | \f | |
264 | ;; Miscellaneous | |
265 | ||
266 | (defun timezone-zone-to-minute (timezone) | |
d51c3cda | 267 | "Translate TIMEZONE to an integer minute offset from GMT. |
6cda144f | 268 | TIMEZONE can be a cons cell containing the output of `current-time-zone', |
d51c3cda RS |
269 | or an integer of the form +-HHMM, or a time zone name." |
270 | (cond | |
271 | ((consp timezone) | |
272 | (/ (car timezone) 60)) | |
273 | (timezone | |
a47a5be5 RS |
274 | (progn |
275 | (setq timezone | |
276 | (or (cdr (assoc (upcase timezone) timezone-world-timezones)) | |
277 | ;; +900 | |
278 | timezone)) | |
279 | (if (stringp timezone) | |
027a4b6b | 280 | (setq timezone (string-to-number timezone))) |
a47a5be5 RS |
281 | ;; Taking account of minute in timezone. |
282 | ;; HHMM -> MM | |
9b1868cc | 283 | (let* ((abszone (abs timezone)) |
a47a5be5 | 284 | (minutes (+ (* 60 (/ abszone 100)) (% abszone 100)))) |
d51c3cda RS |
285 | (if (< timezone 0) (- minutes) minutes)))) |
286 | (t 0))) | |
287 | ||
288 | (defun timezone-time-from-absolute (date seconds) | |
289 | "Compute the UTC time equivalent to DATE at time SECONDS after midnight. | |
6cda144f | 290 | Return a list suitable as an argument to `current-time-zone', |
d51c3cda RS |
291 | or nil if the date cannot be thus represented. |
292 | DATE is the number of days elapsed since the (imaginary) | |
293 | Gregorian date Sunday, December 31, 1 BC." | |
db853edc | 294 | (let* ((current-time-origin 719163) |
d51c3cda RS |
295 | ;; (timezone-absolute-from-gregorian 1 1 1970) |
296 | (days (- date current-time-origin)) | |
297 | (seconds-per-day (float 86400)) | |
298 | (seconds (+ seconds (* days seconds-per-day))) | |
299 | (current-time-arithmetic-base (float 65536)) | |
300 | (hi (floor (/ seconds current-time-arithmetic-base))) | |
301 | (hibase (* hi current-time-arithmetic-base)) | |
302 | (lo (floor (- seconds hibase)))) | |
303 | (and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow. | |
304 | (cons hi lo)))) | |
a47a5be5 | 305 | |
d51c3cda RS |
306 | (defun timezone-time-zone-from-absolute (date seconds) |
307 | "Compute the local time zone for DATE at time SECONDS after midnight. | |
6cda144f | 308 | Return a list in the same format as `current-time-zone's result, |
d51c3cda RS |
309 | or nil if the local time zone could not be computed. |
310 | DATE is the number of days elapsed since the (imaginary) | |
311 | Gregorian date Sunday, December 31, 1 BC." | |
312 | (and (fboundp 'current-time-zone) | |
313 | (let ((utc-time (timezone-time-from-absolute date seconds))) | |
314 | (and utc-time | |
315 | (let ((zone (current-time-zone utc-time))) | |
316 | (and (car zone) zone)))))) | |
317 | ||
318 | (defun timezone-fix-time (date local timezone) | |
dce33aad | 319 | "Convert DATE (default timezone LOCAL) to YYYY-MM-DD-HH-MM-SS-ZONE vector. |
d51c3cda RS |
320 | If LOCAL is nil, it is assumed to be GMT. |
321 | If TIMEZONE is nil, use the local time zone." | |
322 | (let* ((date (timezone-parse-date date)) | |
027a4b6b | 323 | (year (string-to-number (aref date 0))) |
d1912872 | 324 | (year (cond ((< year 69) |
13d76d1c RS |
325 | (+ year 2000)) |
326 | ((< year 100) | |
327 | (+ year 1900)) | |
d1912872 DL |
328 | ((< year 1000) ; possible 3-digit years. |
329 | (+ year 1900)) | |
13d76d1c | 330 | (t year))) |
027a4b6b JB |
331 | (month (string-to-number (aref date 1))) |
332 | (day (string-to-number (aref date 2))) | |
d51c3cda | 333 | (time (timezone-parse-time (aref date 3))) |
027a4b6b JB |
334 | (hour (string-to-number (aref time 0))) |
335 | (minute (string-to-number (aref time 1))) | |
336 | (second (string-to-number (aref time 2))) | |
d51c3cda RS |
337 | (local (or (aref date 4) local)) ;Use original if defined |
338 | (timezone | |
339 | (or timezone | |
340 | (timezone-time-zone-from-absolute | |
341 | (timezone-absolute-from-gregorian month day year) | |
342 | (+ second (* 60 (+ minute (* 60 hour))))))) | |
343 | (diff (- (timezone-zone-to-minute timezone) | |
344 | (timezone-zone-to-minute local))) | |
345 | (minute (+ minute diff)) | |
9b1868cc | 346 | (hour-fix (floor minute 60))) |
a47a5be5 | 347 | (setq hour (+ hour hour-fix)) |
d51c3cda RS |
348 | (setq minute (- minute (* 60 hour-fix))) |
349 | ;; HOUR may be larger than 24 or smaller than 0. | |
350 | (cond ((<= 24 hour) ;24 -> 00 | |
351 | (setq hour (- hour 24)) | |
352 | (setq day (1+ day)) | |
ca87e960 DL |
353 | (when (< (timezone-last-day-of-month month year) day) |
354 | (setq month (1+ month)) | |
355 | (setq day 1) | |
356 | (when (< 12 month) | |
357 | (setq month 1) | |
358 | (setq year (1+ year))))) | |
d51c3cda RS |
359 | ((> 0 hour) |
360 | (setq hour (+ hour 24)) | |
361 | (setq day (1- day)) | |
ca87e960 DL |
362 | (when (> 1 day) |
363 | (setq month (1- month)) | |
364 | (when (> 1 month) | |
365 | (setq month 12) | |
366 | (setq year (1- year))) | |
367 | (setq day (timezone-last-day-of-month month year))))) | |
d51c3cda | 368 | (vector year month day hour minute second timezone))) |
a47a5be5 RS |
369 | |
370 | ;; Partly copied from Calendar program by Edward M. Reingold. | |
371 | ;; Thanks a lot. | |
372 | ||
373 | (defun timezone-last-day-of-month (month year) | |
374 | "The last day in MONTH during YEAR." | |
375 | (if (and (= month 2) (timezone-leap-year-p year)) | |
376 | 29 | |
377 | (aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month)))) | |
378 | ||
379 | (defun timezone-leap-year-p (year) | |
6cda144f | 380 | "Return t if YEAR is a Gregorian leap year." |
a47a5be5 RS |
381 | (or (and (zerop (% year 4)) |
382 | (not (zerop (% year 100)))) | |
383 | (zerop (% year 400)))) | |
aa56d805 | 384 | |
d51c3cda RS |
385 | (defun timezone-day-number (month day year) |
386 | "Return the day number within the year of the date month/day/year." | |
387 | (let ((day-of-year (+ day (* 31 (1- month))))) | |
388 | (if (> month 2) | |
389 | (progn | |
390 | (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10))) | |
391 | (if (timezone-leap-year-p year) | |
392 | (setq day-of-year (1+ day-of-year))))) | |
393 | day-of-year)) | |
394 | ||
395 | (defun timezone-absolute-from-gregorian (month day year) | |
396 | "The number of days between the Gregorian date 12/31/1 BC and month/day/year. | |
397 | The Gregorian date Sunday, December 31, 1 BC is imaginary." | |
398 | (+ (timezone-day-number month day year);; Days this year | |
399 | (* 365 (1- year));; + Days in prior years | |
400 | (/ (1- year) 4);; + Julian leap years | |
401 | (- (/ (1- year) 100));; - century years | |
402 | (/ (1- year) 400)));; + Gregorian leap years | |
403 | ||
64606d07 DL |
404 | (provide 'timezone) |
405 | ||
aa56d805 | 406 | ;;; timezone.el ends here |