1 ;;; cal-bahai.el --- calendar functions for the Bahá'í calendar. -*- coding: utf-8 -*-
3 ;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 ;; Free Software Foundation, Inc.
6 ;; Author: John Wiegley <johnw@gnu.org>
8 ;; Human-Keywords: Bahá'í calendar, Bahá'í, Baha'i, Bahai, calendar, diary
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 3, or (at your option)
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.
29 ;; This collection of functions implements the features of calendar.el
30 ;; and diary.el that deal with the Bahá'í calendar.
32 ;; The Bahá'í (http://www.bahai.org) calendar system is based on a
33 ;; solar cycle of 19 months with 19 days each. The four remaining
34 ;; "intercalary" days are called the Ayyám-i-Há (days of Há), and are
35 ;; placed between the 18th and 19th months. They are meant as a time
36 ;; of festivals preceding the 19th month, which is the month of
37 ;; fasting. In Gregorian leap years, there are 5 of these days (Há
38 ;; has the numerical value of 5 in the arabic abjad, or
39 ;; letter-to-number, reckoning).
41 ;; Each month is named after an attribute of God, as are the 19 days
42 ;; -- which have the same names as the months. There is also a name
43 ;; for each year in every 19 year cycle. These cycles are called
44 ;; Váhids. A cycle of 19 Váhids (361 years) is called a Kullu-Shay,
45 ;; which means "all things".
47 ;; The calendar was named the "Badí` calendar" by its author, the Báb.
48 ;; It uses a week of seven days, corresponding to the Gregorian week,
49 ;; each of which has its own name, again patterned after the
52 ;; Note: The days of Ayyám-i-Há are encoded as zero and negative
53 ;; offsets from the first day of the final month. So, (19 -3 157) is
54 ;; the first day of Ayyám-i-Há, in the year 157 BE.
59 (defvar displayed-month)
60 (defvar displayed-year)
62 (defvar original-date)
66 (defconst calendar-bahai-month-name-array
67 ["Bahá" "Jalál" "Jamál" "`Azamat" "Núr" "Rahmat" "Kalimát" "Kamál"
68 "Asmá" "`Izzat" "Mashiyyat" "`Ilm" "Qudrat" "Qawl" "Masá'il"
69 "Sharaf" "Sultán" "Mulk" "`Alá"])
71 (defconst calendar-bahai-epoch (calendar-absolute-from-gregorian '(3 21 1844))
72 "Absolute date of start of Bahá'í calendar = March 19, 622 A.D. (Julian).")
74 (defun calendar-bahai-leap-year-p (year)
75 "True if YEAR is a leap year on the Bahá'í calendar."
76 (calendar-leap-year-p (+ year 1844)))
78 (defconst calendar-bahai-leap-base
79 (+ (/ 1844 4) (- (/ 1844 100)) (/ 1844 400)))
81 (defun calendar-absolute-from-bahai (date)
82 "Compute absolute date from Bahá'í date DATE.
83 The absolute date is the number of days elapsed since the (imaginary)
84 Gregorian date Sunday, December 31, 1 BC."
85 (let* ((month (extract-calendar-month date))
86 (day (extract-calendar-day date))
87 (year (extract-calendar-year date))
88 (prior-years (+ (1- year) 1844))
89 (leap-days (- (+ (/ prior-years 4) ; Leap days in prior years.
90 (- (/ prior-years 100))
92 calendar-bahai-leap-base)))
93 (+ (1- calendar-bahai-epoch) ; Days before epoch
94 (* 365 (1- year)) ; Days in prior years.
96 (calendar-sum m 1 (< m month) 19)
98 day))) ; Days so far this month.
100 (defun calendar-bahai-from-absolute (date)
101 "Bahá'í year corresponding to the absolute DATE."
102 (if (< date calendar-bahai-epoch)
103 (list 0 0 0) ;; pre-Bahá'í date
104 (let* ((greg (calendar-gregorian-from-absolute date))
105 (year (+ (- (extract-calendar-year greg) 1844)
106 (if (or (> (extract-calendar-month greg) 3)
107 (and (= (extract-calendar-month greg) 3)
108 (>= (extract-calendar-day greg) 21)))
110 (month ;; Search forward from Baha.
111 (1+ (calendar-sum m 1
113 (calendar-absolute-from-bahai
116 (day ;; Calculate the day by subtraction.
118 (1- (calendar-absolute-from-bahai (list month 1 year))))))
119 (list month day year))))
121 (defun calendar-bahai-date-string (&optional date)
122 "String of Bahá'í date of Gregorian DATE.
123 Defaults to today's date if DATE is not given."
124 (let* ((bahai-date (calendar-bahai-from-absolute
125 (calendar-absolute-from-gregorian
126 (or date (calendar-current-date)))))
127 (y (extract-calendar-year bahai-date))
128 (m (extract-calendar-month bahai-date))
129 (d (extract-calendar-day bahai-date)))
134 (aref calendar-bahai-month-name-array (1- m))))
137 (if (calendar-bahai-leap-year-p y)
142 (month (int-to-string m))
143 (year (int-to-string y)))
144 (mapconcat 'eval calendar-date-display-form ""))))
146 (defun calendar-bahai-print-date ()
147 "Show the Bahá'í calendar equivalent of the selected date."
149 (message "Bahá'í date: %s"
150 (calendar-bahai-date-string (calendar-cursor-to-date t))))
152 (defun calendar-bahai-goto-date (date &optional noecho)
153 "Move cursor to Bahá'í date DATE.
154 Echo Bahá'í date unless NOECHO is t."
155 (interactive (calendar-bahai-prompt-for-date))
156 (calendar-goto-date (calendar-gregorian-from-absolute
157 (calendar-absolute-from-bahai date)))
158 (or noecho (calendar-bahai-print-date)))
160 (defun calendar-bahai-prompt-for-date ()
161 "Ask for a Bahá'í date."
162 (let* ((today (calendar-current-date))
164 "Bahá'í calendar year (not 0): "
165 '(lambda (x) (/= x 0))
167 (extract-calendar-year
168 (calendar-bahai-from-absolute
169 (calendar-absolute-from-gregorian today))))))
170 (completion-ignore-case t)
173 "Bahá'í calendar month name: "
175 (append calendar-bahai-month-name-array nil))
177 (calendar-make-alist calendar-bahai-month-name-array
179 (day (calendar-read "Bahá'í calendar day (1-19): "
180 '(lambda (x) (and (< 0 x) (<= x 19))))))
181 (list (list month day year))))
183 (defun diary-bahai-date ()
184 "Bahá'í calendar equivalent of date diary entry."
185 (format "Bahá'í date: %s" (calendar-bahai-date-string date)))
187 (defun holiday-bahai (month day string)
188 "Holiday on MONTH, DAY (Bahá'í) called STRING.
189 If MONTH, DAY (Bahá'í) is visible, the value returned is corresponding
190 Gregorian date in the form of the list (((month day year) STRING)). Returns
191 nil if it is not visible in the current calendar window."
192 (let* ((bahai-date (calendar-bahai-from-absolute
193 (calendar-absolute-from-gregorian
194 (list displayed-month 15 displayed-year))))
195 (m (extract-calendar-month bahai-date))
196 (y (extract-calendar-year bahai-date))
199 nil ;; Bahá'í calendar doesn't apply.
200 (increment-calendar-month m y (- 10 month))
201 (if (> m 7) ;; Bahá'í date might be visible
202 (let ((date (calendar-gregorian-from-absolute
203 (calendar-absolute-from-bahai (list month day y)))))
204 (if (calendar-date-is-visible-p date)
205 (list (list date string))))))))
207 (defun diary-bahai-list-entries ()
208 "Add any Bahá'í date entries from the diary file to `diary-entries-list'.
209 Bahá'í date diary entries must be prefaced by an
210 `bahai-diary-entry-symbol' (normally a `B'). The same diary date
211 forms govern the style of the Bahá'í calendar entries, except that the
212 Bahá'í month names must be given numerically. The Bahá'í months are
213 numbered from 1 to 19 with Bahá being 1 and 19 being `Alá. If a
214 Bahá'í date diary entry begins with a `diary-nonmarking-symbol', the
215 entry will appear in the diary listing, but will not be marked in the
216 calendar. This function is provided for use with the
217 `nongregorian-diary-listing-hook'."
219 (let ((buffer-read-only nil)
220 (diary-modified (buffer-modified-p))
221 (gdate original-date)
222 (mark (regexp-quote diary-nonmarking-symbol)))
223 (dotimes (idummy number)
224 (let* ((d diary-date-forms)
225 (bdate (calendar-bahai-from-absolute
226 (calendar-absolute-from-gregorian gdate)))
227 (month (extract-calendar-month bdate))
228 (day (extract-calendar-day bdate))
229 (year (extract-calendar-year bdate)))
232 ((date-form (if (equal (car (car d)) 'backup)
235 (backup (equal (car (car d)) 'backup))
238 (calendar-day-name gdate) "\\|"
239 (substring (calendar-day-name gdate) 0 3) ".?"))
240 (calendar-month-name-array
241 calendar-bahai-month-name-array)
245 (calendar-month-name month)))
246 (month (concat "\\*\\|0*" (int-to-string month)))
247 (day (concat "\\*\\|0*" (int-to-string day)))
250 "\\*\\|0*" (int-to-string year)
251 (if abbreviated-calendar-year
252 (concat "\\|" (int-to-string (% year 100)))
256 "\\(\\`\\|\^M\\|\n\\)" mark "?"
257 (regexp-quote bahai-diary-entry-symbol)
259 (mapconcat 'eval date-form "\\)\\(")
261 (case-fold-search t))
262 (goto-char (point-min))
263 (while (re-search-forward regexp nil t)
264 (if backup (re-search-backward "\\<" nil t))
265 (if (and (or (char-equal (preceding-char) ?\^M)
266 (char-equal (preceding-char) ?\n))
267 (not (looking-at " \\|\^I")))
268 ;; Diary entry that consists only of date.
270 ;; Found a nonempty diary entry--make it visible and
271 ;; add it to the list.
272 (let ((entry-start (point))
274 (re-search-backward "\^M\\|\n\\|\\`")
275 (setq date-start (point))
276 (re-search-forward "\^M\\|\n" nil t 2)
277 (while (looking-at " \\|\^I")
278 (re-search-forward "\^M\\|\n" nil t))
280 (subst-char-in-region date-start (point) ?\^M ?\n t)
283 (buffer-substring-no-properties entry-start (point))
284 (buffer-substring-no-properties
285 (1+ date-start) (1- entry-start)))))))
288 (calendar-gregorian-from-absolute
289 (1+ (calendar-absolute-from-gregorian gdate)))))
290 (set-buffer-modified-p diary-modified))
291 (goto-char (point-min))))
293 (defun diary-bahai-mark-entries ()
294 "Mark days in the calendar window that have Bahá'í date diary entries.
295 Each entry in diary-file (or included files) visible in the calendar
296 window is marked. Bahá'í date entries are prefaced by a
297 bahai-diary-entry-symbol \(normally a B`I'). The same
298 diary-date-forms govern the style of the Bahá'í calendar entries,
299 except that the Bahá'í month names must be spelled in full. The
300 Bahá'í months are numbered from 1 to 12 with Bahá being 1 and 12 being
301 `Alá. Bahá'í date diary entries that begin with a
302 diary-nonmarking-symbol will not be marked in the calendar. This
303 function is provided for use as part of the
304 nongregorian-diary-marking-hook."
305 (let ((d diary-date-forms))
308 ((date-form (if (equal (car (car d)) 'backup)
310 (car d)));; ignore 'backup directive
311 (dayname (diary-name-pattern calendar-day-name-array))
314 (diary-name-pattern calendar-bahai-month-name-array t)
316 (month "[0-9]+\\|\\*")
318 (year "[0-9]+\\|\\*")
319 (l (length date-form))
320 (d-name-pos (- l (length (memq 'dayname date-form))))
321 (d-name-pos (if (/= l d-name-pos) (+ 2 d-name-pos)))
322 (m-name-pos (- l (length (memq 'monthname date-form))))
323 (m-name-pos (if (/= l m-name-pos) (+ 2 m-name-pos)))
324 (d-pos (- l (length (memq 'day date-form))))
325 (d-pos (if (/= l d-pos) (+ 2 d-pos)))
326 (m-pos (- l (length (memq 'month date-form))))
327 (m-pos (if (/= l m-pos) (+ 2 m-pos)))
328 (y-pos (- l (length (memq 'year date-form))))
329 (y-pos (if (/= l y-pos) (+ 2 y-pos)))
332 "\\(\\`\\|\^M\\|\n\\)"
333 (regexp-quote bahai-diary-entry-symbol)
335 (mapconcat 'eval date-form "\\)\\(")
337 (case-fold-search t))
338 (goto-char (point-min))
339 (while (re-search-forward regexp nil t)
343 (match-beginning d-name-pos)
344 (match-end d-name-pos))))
348 (match-beginning m-name-pos)
349 (match-end m-name-pos))))
350 (mm (string-to-number
353 (match-beginning m-pos)
356 (dd (string-to-number
359 (match-beginning d-pos)
364 (match-beginning y-pos)
368 (if (and (= (length y-str) 2)
369 abbreviated-calendar-year)
371 (extract-calendar-year
372 (calendar-bahai-from-absolute
373 (calendar-absolute-from-gregorian
374 (calendar-current-date)))))
375 (y (+ (string-to-number y-str)
376 (* 100 (/ current-y 100)))))
377 (if (> (- y current-y) 50)
379 (if (> (- current-y y) 50)
382 (string-to-number y-str)))))
384 (mark-calendar-days-named
385 (cdr (assoc-string (substring dd-name 0 3)
387 calendar-day-name-array
389 '(lambda (x) (substring x 0 3)))
392 (if (string-equal mm-name "*")
398 calendar-bahai-month-name-array)
400 (calendar-bahai-mark-date-pattern mm dd yy)))))
403 (defun calendar-bahai-mark-date-pattern (month day year)
404 "Mark dates in calendar window that conform to Bahá'í date MONTH/DAY/YEAR.
405 A value of 0 in any position is a wildcard."
407 (set-buffer calendar-buffer)
408 (if (and (/= 0 month) (/= 0 day))
410 ;; Fully specified Bahá'í date.
411 (let ((date (calendar-gregorian-from-absolute
412 (calendar-absolute-from-bahai
413 (list month day year)))))
414 (if (calendar-date-is-visible-p date)
415 (mark-visible-calendar-date date)))
416 ;; Month and day in any year--this taken from the holiday stuff.
417 (let* ((bahai-date (calendar-bahai-from-absolute
418 (calendar-absolute-from-gregorian
419 (list displayed-month 15 displayed-year))))
420 (m (extract-calendar-month bahai-date))
421 (y (extract-calendar-year bahai-date))
424 nil;; Bahá'í calendar doesn't apply.
425 (increment-calendar-month m y (- 10 month))
426 (if (> m 7);; Bahá'í date might be visible
427 (let ((date (calendar-gregorian-from-absolute
428 (calendar-absolute-from-bahai
429 (list month day y)))))
430 (if (calendar-date-is-visible-p date)
431 (mark-visible-calendar-date date)))))))
432 ;; Not one of the simple cases--check all visible dates for match.
433 ;; Actually, the following code takes care of ALL of the cases, but
434 ;; it's much too slow to be used for the simple (common) cases.
435 (let ((m displayed-month)
439 (increment-calendar-month m y -1)
441 (calendar-absolute-from-gregorian
443 (increment-calendar-month m y 2)
445 (calendar-absolute-from-gregorian
446 (list m (calendar-last-day-of-month m y) y)))
447 (calendar-for-loop date from first-date to last-date do
448 (let* ((b-date (calendar-bahai-from-absolute date))
449 (i-month (extract-calendar-month b-date))
450 (i-day (extract-calendar-day b-date))
451 (i-year (extract-calendar-year b-date)))
452 (and (or (zerop month)
458 (mark-visible-calendar-date
459 (calendar-gregorian-from-absolute date)))))))))
461 (defun diary-bahai-insert-entry (arg)
462 "Insert a diary entry.
463 For the Bahá'í date corresponding to the date indicated by point.
464 Prefix arg will make the entry nonmarking."
466 (let* ((calendar-month-name-array calendar-bahai-month-name-array))
469 bahai-diary-entry-symbol
470 (calendar-date-string
471 (calendar-bahai-from-absolute
472 (calendar-absolute-from-gregorian
473 (calendar-cursor-to-date t)))
477 (defun diary-bahai-insert-monthly-entry (arg)
478 "Insert a monthly diary entry.
479 For the day of the Bahá'í month corresponding to the date indicated by point.
480 Prefix arg will make the entry nonmarking."
482 (let* ((calendar-date-display-form
483 (if european-calendar-style '(day " * ") '("* " day )))
484 (calendar-month-name-array calendar-bahai-month-name-array))
487 bahai-diary-entry-symbol
488 (calendar-date-string
489 (calendar-bahai-from-absolute
490 (calendar-absolute-from-gregorian
491 (calendar-cursor-to-date t)))))
494 (defun diary-bahai-insert-yearly-entry (arg)
495 "Insert an annual diary entry.
496 For the day of the Bahá'í year corresponding to the date indicated by point.
497 Prefix arg will make the entry nonmarking."
499 (let* ((calendar-date-display-form
500 (if european-calendar-style
502 '(monthname " " day)))
503 (calendar-month-name-array calendar-bahai-month-name-array))
506 bahai-diary-entry-symbol
507 (calendar-date-string
508 (calendar-bahai-from-absolute
509 (calendar-absolute-from-gregorian
510 (calendar-cursor-to-date t)))))
513 ;; Backward compatibility.
514 (define-obsolete-function-alias
515 'list-bahai-diary-entries 'diary-bahai-list-entries "23.1")
516 (define-obsolete-function-alias
517 'mark-bahai-diary-entries 'diary-bahai-mark-entries "23.1")
518 (define-obsolete-function-alias
519 'insert-bahai-diary-entry 'diary-bahai-insert-entry "23.1")
520 (define-obsolete-function-alias
521 'insert-monthly-bahai-diary-entry 'diary-bahai-insert-monthly-entry "23.1")
522 (define-obsolete-function-alias
523 'insert-yearly-bahai-diary-entry 'diary-bahai-insert-yearly-entry "23.1")
524 (define-obsolete-function-alias
525 'mark-bahai-calendar-date-pattern 'calendar-bahai-mark-date-pattern "23.1")
526 (define-obsolete-function-alias
527 'calendar-goto-bahai-date 'calendar-bahai-goto-date "23.1")
528 (define-obsolete-function-alias
529 'calendar-print-bahai-date 'calendar-bahai-print-date "23.1")
533 ;; arch-tag: c1cb1d67-862a-4264-a01c-41cb4df01f14
534 ;;; cal-bahai.el ends here