Commit | Line | Data |
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1a06eabd | 1 | ;;; holidays.el --- holiday functions for the calendar package |
fc68affa | 2 | |
a96a5fca | 3 | ;; Copyright (C) 1989, 90, 92, 93, 94, 1997 Free Software Foundation, Inc. |
3a801d0c | 4 | |
fc68affa | 5 | ;; Author: Edward M. Reingold <reingold@cs.uiuc.edu> |
7e1dae73 | 6 | ;; Keywords: holidays, calendar |
fc68affa | 7 | |
1802278a JB |
8 | ;; This file is part of GNU Emacs. |
9 | ||
59243403 RS |
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation; either version 2, or (at your option) | |
13 | ;; any later version. | |
8ec105a0 | 14 | |
1802278a | 15 | ;; GNU Emacs is distributed in the hope that it will be useful, |
59243403 RS |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
b578f267 EN |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
1802278a | 24 | |
fc68affa ER |
25 | ;;; Commentary: |
26 | ||
1802278a JB |
27 | ;; This collection of functions implements the holiday features as described |
28 | ;; in calendar.el. | |
29 | ||
1802278a JB |
30 | ;; Technical details of all the calendrical calculations can be found in |
31 | ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold, | |
a96a5fca PE |
32 | ;; Cambridge University Press (1997). |
33 | ||
34 | ;; An earlier version of the technical details appeared in | |
35 | ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold, | |
1802278a | 36 | ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990), |
7e1dae73 JB |
37 | ;; pages 899-928. ``Calendrical Calculations, Part II: Three Historical |
38 | ;; Calendars'' by E. M. Reingold, N. Dershowitz, and S. M. Clamen, | |
c8d190a5 JB |
39 | ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993), |
40 | ;; pages 383-404. | |
7e1dae73 JB |
41 | |
42 | ;; Hard copies of these two papers can be obtained by sending email to | |
43 | ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and | |
44 | ;; the message BODY containing your mailing address (snail). | |
1802278a | 45 | |
a96a5fca PE |
46 | ;; Comments, corrections, and improvements should be sent to |
47 | ;; Edward M. Reingold Department of Computer Science | |
48 | ;; (217) 333-6733 University of Illinois at Urbana-Champaign | |
49 | ;; reingold@cs.uiuc.edu 1304 West Springfield Avenue | |
50 | ;; Urbana, Illinois 61801 | |
51 | ||
fc68affa ER |
52 | ;;; Code: |
53 | ||
1802278a | 54 | (require 'calendar) |
e5d77022 | 55 | |
32933edb ER |
56 | (autoload 'holiday-julian "cal-julian" |
57 | "Holiday on MONTH, DAY (Julian) called STRING." | |
58 | t) | |
59 | ||
60 | (autoload 'holiday-hebrew "cal-hebrew" | |
61 | "Holiday on MONTH, DAY (Hebrew) called STRING." | |
62 | t) | |
63 | ||
64 | (autoload 'holiday-rosh-hashanah-etc "cal-hebrew" | |
65 | "List of dates related to Rosh Hashanah, as visible in calendar window." | |
66 | t) | |
67 | ||
68 | (autoload 'holiday-hanukkah "cal-hebrew" | |
69 | "List of dates related to Hanukkah, as visible in calendar window." | |
70 | t) | |
71 | ||
72 | (autoload 'holiday-passover-etc "cal-hebrew" | |
73 | "List of dates related to Passover, as visible in calendar window." | |
74 | t) | |
75 | ||
76 | (autoload 'holiday-tisha-b-av-etc "cal-hebrew" | |
77 | "List of dates around Tisha B'Av, as visible in calendar window." | |
78 | t) | |
79 | ||
327b6868 | 80 | (autoload 'holiday-islamic "cal-islam" |
32933edb ER |
81 | "Holiday on MONTH, DAY (Islamic) called STRING." |
82 | t) | |
83 | ||
327b6868 | 84 | (autoload 'holiday-chinese-new-year "cal-china" |
32933edb ER |
85 | "Date of Chinese New Year." |
86 | t) | |
87 | ||
8ec105a0 | 88 | (autoload 'solar-equinoxes-solstices "solar" |
7e1dae73 JB |
89 | "Date and time of equinoxes and solstices, if visible in the calendar window. |
90 | Requires floating point." | |
91 | t) | |
92 | ||
c8224de6 | 93 | ;;;###autoload |
7e1dae73 | 94 | (defun holidays (&optional arg) |
1802278a | 95 | "Display the holidays for last month, this month, and next month. |
7e1dae73 JB |
96 | If called with an optional prefix argument, prompts for month and year. |
97 | ||
1802278a | 98 | This function is suitable for execution in a .emacs file." |
7e1dae73 | 99 | (interactive "P") |
1802278a | 100 | (save-excursion |
7e1dae73 | 101 | (let* ((completion-ignore-case t) |
c99d4526 ER |
102 | (date (if arg |
103 | (calendar-read-date t) | |
104 | (calendar-current-date))) | |
105 | (displayed-month (extract-calendar-month date)) | |
106 | (displayed-year (extract-calendar-year date))) | |
1802278a JB |
107 | (list-calendar-holidays)))) |
108 | ||
40b14a0c | 109 | ;;;###autoload |
056a21c4 RS |
110 | (defun list-holidays (y1 y2 &optional l label) |
111 | "Display holidays for years Y1 to Y2 (inclusive). | |
112 | ||
113 | The optional list of holidays L defaults to `calendar-holidays'. See the | |
114 | documentation for that variable for a description of holiday lists. | |
115 | ||
116 | The optional LABEL is used to label the buffer created." | |
117 | (interactive | |
118 | (let* ((start-year (calendar-read | |
119 | "Starting year of holidays (>0): " | |
120 | '(lambda (x) (> x 0)) | |
121 | (int-to-string (extract-calendar-year | |
122 | (calendar-current-date))))) | |
123 | (end-year (calendar-read | |
124 | (format "Ending year (inclusive) of holidays (>=%s): " | |
125 | start-year) | |
126 | '(lambda (x) (>= x start-year)) | |
127 | (int-to-string start-year))) | |
128 | (completion-ignore-case t) | |
129 | (lists | |
130 | (list | |
131 | (cons "All" calendar-holidays) | |
132 | (if (fboundp 'atan) | |
133 | (cons "Equinoxes/Solstices" | |
134 | (list (list 'solar-equinoxes-solstices)))) | |
135 | (if general-holidays (cons "General" general-holidays)) | |
136 | (if local-holidays (cons "Local" local-holidays)) | |
137 | (if other-holidays (cons "Other" other-holidays)) | |
138 | (if christian-holidays (cons "Christian" christian-holidays)) | |
139 | (if hebrew-holidays (cons "Hebrew" hebrew-holidays)) | |
140 | (if islamic-holidays (cons "Islamic" islamic-holidays)) | |
141 | (if oriental-holidays (cons "Oriental" oriental-holidays)) | |
142 | (if solar-holidays (cons "Solar" solar-holidays)) | |
143 | (cons "Ask" nil))) | |
144 | (choice (capitalize | |
145 | (completing-read "List (TAB for choices): " lists nil t))) | |
146 | (which (if (string-equal choice "Ask") | |
147 | (eval (read-variable "Enter list name: ")) | |
148 | (cdr (assoc choice lists)))) | |
149 | (name (if (string-equal choice "Equinoxes/Solstices") | |
150 | choice | |
ebad70de | 151 | (if (member choice '("Ask" "")) |
a1506d29 | 152 | "Holidays" |
056a21c4 RS |
153 | (format "%s Holidays" choice))))) |
154 | (list start-year end-year which name))) | |
155 | (message "Computing holidays...") | |
156 | (let* ((holiday-buffer "*Holidays*") | |
157 | (calendar-holidays (if l l calendar-holidays)) | |
ebad70de | 158 | (title (or label "Holidays")) |
056a21c4 RS |
159 | (holiday-list nil) |
160 | (s (calendar-absolute-from-gregorian (list 2 1 y1))) | |
161 | (e (calendar-absolute-from-gregorian (list 11 1 y2))) | |
162 | (d s) | |
163 | (never t) | |
164 | (displayed-month 2) | |
165 | (displayed-year y1)) | |
166 | (while (or never (<= d e)) | |
167 | (setq holiday-list (append holiday-list (calendar-holiday-list))) | |
168 | (setq never nil) | |
169 | (increment-calendar-month displayed-month displayed-year 3) | |
170 | (setq d (calendar-absolute-from-gregorian | |
171 | (list displayed-month 1 displayed-year)))) | |
ebad70de RS |
172 | (save-excursion |
173 | (set-buffer (get-buffer-create holiday-buffer)) | |
174 | (setq buffer-read-only nil) | |
175 | (calendar-set-mode-line | |
176 | (if (= y1 y2) | |
177 | (format "%s for %s" title y1) | |
178 | (format "%s for %s-%s" title y1 y2))) | |
179 | (erase-buffer) | |
180 | (goto-char (point-min)) | |
181 | (insert | |
182 | (mapconcat | |
183 | '(lambda (x) (concat (calendar-date-string (car x)) | |
184 | ": " (car (cdr x)))) | |
185 | holiday-list "\n")) | |
186 | (goto-char (point-min)) | |
187 | (set-buffer-modified-p nil) | |
188 | (setq buffer-read-only t) | |
189 | (display-buffer holiday-buffer) | |
190 | (message "Computing holidays...done")))) | |
191 | ||
056a21c4 | 192 | |
1802278a JB |
193 | (defun check-calendar-holidays (date) |
194 | "Check the list of holidays for any that occur on DATE. | |
195 | The value returned is a list of strings of relevant holiday descriptions. | |
196 | The holidays are those in the list calendar-holidays." | |
197 | (let* ((displayed-month (extract-calendar-month date)) | |
198 | (displayed-year (extract-calendar-year date)) | |
199 | (h (calendar-holiday-list)) | |
200 | (holiday-list)) | |
201 | (while h | |
202 | (if (calendar-date-equal date (car (car h))) | |
203 | (setq holiday-list (append holiday-list (cdr (car h))))) | |
204 | (setq h (cdr h))) | |
205 | holiday-list)) | |
206 | ||
207 | (defun calendar-cursor-holidays () | |
208 | "Find holidays for the date specified by the cursor in the calendar window." | |
209 | (interactive) | |
210 | (message "Checking holidays...") | |
56e7830d | 211 | (let* ((date (calendar-cursor-to-date t)) |
1802278a JB |
212 | (date-string (calendar-date-string date)) |
213 | (holiday-list (check-calendar-holidays date)) | |
214 | (holiday-string (mapconcat 'identity holiday-list "; ")) | |
215 | (msg (format "%s: %s" date-string holiday-string))) | |
216 | (if (not holiday-list) | |
217 | (message "No holidays known for %s" date-string) | |
8ec105a0 | 218 | (if (<= (length msg) (frame-width)) |
eec5a2e4 | 219 | (message "%s" msg) |
1802278a JB |
220 | (set-buffer (get-buffer-create holiday-buffer)) |
221 | (setq buffer-read-only nil) | |
7e1dae73 | 222 | (calendar-set-mode-line date-string) |
1802278a JB |
223 | (erase-buffer) |
224 | (insert (mapconcat 'identity holiday-list "\n")) | |
225 | (goto-char (point-min)) | |
226 | (set-buffer-modified-p nil) | |
227 | (setq buffer-read-only t) | |
228 | (display-buffer holiday-buffer) | |
229 | (message "Checking holidays...done"))))) | |
230 | ||
231 | (defun mark-calendar-holidays () | |
232 | "Mark notable days in the calendar window." | |
233 | (interactive) | |
234 | (setq mark-holidays-in-calendar t) | |
235 | (message "Marking holidays...") | |
236 | (let ((holiday-list (calendar-holiday-list))) | |
237 | (while holiday-list | |
238 | (mark-visible-calendar-date | |
239 | (car (car holiday-list)) calendar-holiday-marker) | |
240 | (setq holiday-list (cdr holiday-list)))) | |
241 | (message "Marking holidays...done")) | |
242 | ||
243 | (defun list-calendar-holidays () | |
244 | "Create a buffer containing the holidays for the current calendar window. | |
245 | The holidays are those in the list calendar-notable-days. Returns t if any | |
246 | holidays are found, nil if not." | |
247 | (interactive) | |
248 | (message "Looking up holidays...") | |
249 | (let ((holiday-list (calendar-holiday-list)) | |
250 | (m1 displayed-month) | |
251 | (y1 displayed-year) | |
252 | (m2 displayed-month) | |
253 | (y2 displayed-year)) | |
254 | (if (not holiday-list) | |
255 | (progn | |
256 | (message "Looking up holidays...none found") | |
257 | nil) | |
258 | (set-buffer (get-buffer-create holiday-buffer)) | |
259 | (setq buffer-read-only nil) | |
260 | (increment-calendar-month m1 y1 -1) | |
261 | (increment-calendar-month m2 y2 1) | |
7e1dae73 | 262 | (calendar-set-mode-line |
1d34f349 RS |
263 | (if (= y1 y2) |
264 | (format "Notable Dates from %s to %s, %d%%-" | |
265 | (calendar-month-name m1) (calendar-month-name m2) y2) | |
266 | (format "Notable Dates from %s, %d to %s, %d%%-" | |
267 | (calendar-month-name m1) y1 (calendar-month-name m2) y2))) | |
1802278a JB |
268 | (erase-buffer) |
269 | (insert | |
270 | (mapconcat | |
271 | '(lambda (x) (concat (calendar-date-string (car x)) | |
272 | ": " (car (cdr x)))) | |
273 | holiday-list "\n")) | |
274 | (goto-char (point-min)) | |
275 | (set-buffer-modified-p nil) | |
276 | (setq buffer-read-only t) | |
277 | (display-buffer holiday-buffer) | |
278 | (message "Looking up holidays...done") | |
279 | t))) | |
280 | ||
281 | (defun calendar-holiday-list () | |
282 | "Form the list of holidays that occur on dates in the calendar window. | |
283 | The holidays are those in the list calendar-holidays." | |
8ec105a0 | 284 | (let ((p calendar-holidays) |
1802278a JB |
285 | (holiday-list)) |
286 | (while p | |
8ec105a0 JB |
287 | (let* ((holidays |
288 | (if calendar-debug-sexp | |
289 | (let ((stack-trace-on-error t)) | |
290 | (eval (car p))) | |
291 | (condition-case nil | |
292 | (eval (car p)) | |
293 | (error (beep) | |
294 | (message "Bad holiday list item: %s" (car p)) | |
295 | (sleep-for 2)))))) | |
1802278a JB |
296 | (if holidays |
297 | (setq holiday-list (append holidays holiday-list)))) | |
298 | (setq p (cdr p))) | |
299 | (setq holiday-list (sort holiday-list 'calendar-date-compare)))) | |
300 | ||
301 | ;; Below are the functions that calculate the dates of holidays; these | |
8ec105a0 JB |
302 | ;; are eval'ed in the function calendar-holiday-list. If you |
303 | ;; write other such functions, be sure to imitate the style used below. | |
304 | ;; Remember that each function must return a list of items of the form | |
305 | ;; ((month day year) string) of VISIBLE dates in the calendar window. | |
306 | ||
307 | (defun holiday-fixed (month day string) | |
308 | "Holiday on MONTH, DAY (Gregorian) called STRING. | |
309 | If MONTH, DAY is visible, the value returned is the list (((MONTH DAY year) | |
310 | STRING)). Returns nil if it is not visible in the current calendar window." | |
311 | (let ((m displayed-month) | |
312 | (y displayed-year)) | |
1802278a JB |
313 | (increment-calendar-month m y (- 11 month)) |
314 | (if (> m 9) | |
315 | (list (list (list month day y) string))))) | |
316 | ||
8ec105a0 | 317 | (defun holiday-float (month dayname n string &optional day) |
151eeaa7 | 318 | "Holiday on MONTH, DAYNAME (Nth occurrence) called STRING. |
8ec105a0 | 319 | If the Nth DAYNAME in MONTH is visible, the value returned is the list |
a4e104bf | 320 | \(((MONTH DAY year) STRING)). |
8ec105a0 JB |
321 | |
322 | If N<0, count backward from the end of MONTH. | |
323 | ||
151eeaa7 | 324 | An optional parameter DAY means the Nth DAYNAME on or after/before MONTH DAY. |
8ec105a0 | 325 | |
1802278a | 326 | Returns nil if it is not visible in the current calendar window." |
151eeaa7 RS |
327 | ;; This is messy because the holiday may be visible, while the date on which |
328 | ;; it is based is not. For example, the first Monday after December 30 may be | |
329 | ;; visible when January is not. For large values of |n| the problem is more | |
330 | ;; grotesque. If we didn't have to worry about such cases, we could just use | |
331 | ||
332 | ;; (let ((m displayed-month) | |
333 | ;; (y displayed-year)) | |
334 | ;; (increment-calendar-month m y (- 11 month)) | |
335 | ;; (if (> m 9); month in year y is visible | |
336 | ;; (list (list (calendar-nth-named-day n dayname month y day) string))))) | |
337 | ||
338 | ;; which is the way the function was originally written. | |
339 | ||
340 | (let* ((m1 displayed-month) | |
341 | (y1 displayed-year) | |
342 | (m2 m1) | |
343 | (y2 y1)) | |
344 | (increment-calendar-month m1 y1 -1) | |
345 | (increment-calendar-month m2 y2 1) | |
346 | (let* ((d1; first possible base date for holiday | |
347 | (+ (calendar-nth-named-absday 1 dayname m1 y1) | |
348 | (* -7 n) | |
349 | (if (> n 0) 1 -7))) | |
350 | (d2; last possible base date for holiday | |
351 | (+ (calendar-nth-named-absday -1 dayname m2 y2) | |
352 | (* -7 n) | |
353 | (if (> n 0) 7 -1))) | |
354 | (y1 (extract-calendar-year (calendar-gregorian-from-absolute d1))) | |
355 | (y2 (extract-calendar-year (calendar-gregorian-from-absolute d2))) | |
356 | (y; year of base date | |
357 | (if (or (= y1 y2) (> month 9)) | |
358 | y1 | |
359 | y2)) | |
360 | (d; day of base date | |
361 | (or day (if (> n 0) | |
362 | 1 | |
363 | (calendar-last-day-of-month month y)))) | |
364 | (date; base date for holiday | |
365 | (calendar-absolute-from-gregorian (list month d y)))) | |
366 | (if (and (<= d1 date) (<= date d2)) | |
367 | (list (list (calendar-nth-named-day n dayname month y d) | |
368 | string)))))) | |
8ec105a0 | 369 | |
8ec105a0 | 370 | (defun holiday-sexp (sexp string) |
7e1dae73 | 371 | "Sexp holiday for dates in the calendar window. |
8ec105a0 JB |
372 | SEXP is an expression in variable `year' evaluates to `date'. |
373 | ||
374 | STRING is an expression in `date' that evaluates to the holiday description | |
375 | of `date'. | |
376 | ||
377 | If `date' is visible in the calendar window, the holiday STRING is on that | |
378 | date. If date is nil, or if the date is not visible, there is no holiday." | |
7e1dae73 JB |
379 | (let ((m displayed-month) |
380 | (y displayed-year)) | |
381 | (increment-calendar-month m y -1) | |
382 | (filter-visible-calendar-holidays | |
383 | (append | |
8ec105a0 JB |
384 | (let* ((year y) |
385 | (date (eval sexp)) | |
386 | (string (if date (eval string)))) | |
387 | (list (list date string))) | |
388 | (let* ((year (1+ y)) | |
389 | (date (eval sexp)) | |
390 | (string (if date (eval string)))) | |
391 | (list (list date string))))))) | |
392 | ||
393 | (defun holiday-advent () | |
1802278a JB |
394 | "Date of Advent, if visible in calendar window." |
395 | (let ((year displayed-year) | |
396 | (month displayed-month)) | |
397 | (increment-calendar-month month year -1) | |
398 | (let ((advent (calendar-gregorian-from-absolute | |
399 | (calendar-dayname-on-or-before 0 | |
400 | (calendar-absolute-from-gregorian | |
401 | (list 12 3 year)))))) | |
402 | (if (calendar-date-is-visible-p advent) | |
403 | (list (list advent "Advent")))))) | |
404 | ||
8ec105a0 | 405 | (defun holiday-easter-etc () |
1802278a JB |
406 | "List of dates related to Easter, as visible in calendar window." |
407 | (if (and (> displayed-month 5) (not all-christian-calendar-holidays)) | |
408 | nil;; Ash Wednesday, Good Friday, and Easter are not visible. | |
409 | (let* ((century (1+ (/ displayed-year 100))) | |
410 | (shifted-epact ;; Age of moon for April 5... | |
411 | (% (+ 14 (* 11 (% displayed-year 19));; ...by Nicaean rule | |
412 | (- ;; ...corrected for the Gregorian century rule | |
413 | (/ (* 3 century) 4)) | |
414 | (/ ;; ...corrected for Metonic cycle inaccuracy. | |
415 | (+ 5 (* 8 century)) 25) | |
416 | (* 30 century));; Keeps value positive. | |
417 | 30)) | |
418 | (adjusted-epact ;; Adjust for 29.5 day month. | |
419 | (if (or (= shifted-epact 0) | |
420 | (and (= shifted-epact 1) (< 10 (% displayed-year 19)))) | |
421 | (1+ shifted-epact) | |
422 | shifted-epact)) | |
423 | (paschal-moon ;; Day after the full moon on or after March 21. | |
424 | (- (calendar-absolute-from-gregorian (list 4 19 displayed-year)) | |
425 | adjusted-epact)) | |
426 | (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7))) | |
427 | (mandatory | |
428 | (list | |
429 | (list (calendar-gregorian-from-absolute abs-easter) | |
430 | "Easter Sunday") | |
431 | (list (calendar-gregorian-from-absolute (- abs-easter 2)) | |
432 | "Good Friday") | |
433 | (list (calendar-gregorian-from-absolute (- abs-easter 46)) | |
434 | "Ash Wednesday"))) | |
435 | (optional | |
436 | (list | |
437 | (list (calendar-gregorian-from-absolute (- abs-easter 63)) | |
438 | "Septuagesima Sunday") | |
439 | (list (calendar-gregorian-from-absolute (- abs-easter 56)) | |
440 | "Sexagesima Sunday") | |
441 | (list (calendar-gregorian-from-absolute (- abs-easter 49)) | |
442 | "Shrove Sunday") | |
443 | (list (calendar-gregorian-from-absolute (- abs-easter 48)) | |
444 | "Shrove Monday") | |
445 | (list (calendar-gregorian-from-absolute (- abs-easter 47)) | |
446 | "Shrove Tuesday") | |
447 | (list (calendar-gregorian-from-absolute (- abs-easter 14)) | |
448 | "Passion Sunday") | |
449 | (list (calendar-gregorian-from-absolute (- abs-easter 7)) | |
450 | "Palm Sunday") | |
451 | (list (calendar-gregorian-from-absolute (- abs-easter 3)) | |
452 | "Maundy Thursday") | |
453 | (list (calendar-gregorian-from-absolute (+ abs-easter 35)) | |
454 | "Rogation Sunday") | |
455 | (list (calendar-gregorian-from-absolute (+ abs-easter 39)) | |
2ba08787 | 456 | "Ascension Day") |
1802278a JB |
457 | (list (calendar-gregorian-from-absolute (+ abs-easter 49)) |
458 | "Pentecost (Whitsunday)") | |
459 | (list (calendar-gregorian-from-absolute (+ abs-easter 50)) | |
69f5afe4 | 460 | "Whitmonday") |
1802278a JB |
461 | (list (calendar-gregorian-from-absolute (+ abs-easter 56)) |
462 | "Trinity Sunday") | |
463 | (list (calendar-gregorian-from-absolute (+ abs-easter 60)) | |
464 | "Corpus Christi"))) | |
465 | (output-list | |
466 | (filter-visible-calendar-holidays mandatory))) | |
467 | (if all-christian-calendar-holidays | |
468 | (setq output-list | |
a1506d29 | 469 | (append |
1802278a JB |
470 | (filter-visible-calendar-holidays optional) |
471 | output-list))) | |
472 | output-list))) | |
473 | ||
8ec105a0 JB |
474 | (defun holiday-greek-orthodox-easter () |
475 | "Date of Easter according to the rule of the Council of Nicaea." | |
7e1dae73 JB |
476 | (let ((m displayed-month) |
477 | (y displayed-year)) | |
478 | (increment-calendar-month m y 1) | |
479 | (let* ((julian-year | |
480 | (extract-calendar-year | |
481 | (calendar-julian-from-absolute | |
482 | (calendar-absolute-from-gregorian | |
483 | (list m (calendar-last-day-of-month m y) y))))) | |
484 | (shifted-epact ;; Age of moon for April 5. | |
485 | (% (+ 14 | |
486 | (* 11 (% julian-year 19))) | |
487 | 30)) | |
488 | (paschal-moon ;; Day after full moon on or after March 21. | |
489 | (- (calendar-absolute-from-julian (list 4 19 julian-year)) | |
490 | shifted-epact)) | |
491 | (nicaean-easter;; Sunday following the Paschal moon | |
492 | (calendar-gregorian-from-absolute | |
493 | (calendar-dayname-on-or-before 0 (+ paschal-moon 7))))) | |
494 | (if (calendar-date-is-visible-p nicaean-easter) | |
495 | (list (list nicaean-easter "Pascha (Greek Orthodox Easter)")))))) | |
496 | ||
1802278a JB |
497 | (defun filter-visible-calendar-holidays (l) |
498 | "Return a list of all visible holidays of those on L." | |
499 | (let ((visible) | |
500 | (p l)) | |
501 | (while p | |
c8d190a5 JB |
502 | (and (car (car p)) |
503 | (calendar-date-is-visible-p (car (car p))) | |
504 | (setq visible (append (list (car p)) visible))) | |
1802278a JB |
505 | (setq p (cdr p))) |
506 | visible)) | |
49116ac0 JB |
507 | |
508 | (provide 'holidays) | |
509 | ||
1a06eabd | 510 | ;;; holidays.el ends here |