code.delx.au - gnu-emacs/blob - lisp/calendar/holidays.el

   1 ;;; holidays.el --- holiday functions for the calendar package
   2
   3 ;;; Copyright (C) 1989, 1990, 1992 Free Software Foundation, Inc.
   4
   5 ;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
   6 ;; Keywords: holidays, calendar
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is distributed in the hope that it will be useful,
  11 ;; but WITHOUT ANY WARRANTY.  No author or distributor
  12 ;; accepts responsibility to anyone for the consequences of using it
  13 ;; or for whether it serves any particular purpose or works at all,
  14 ;; unless he says so in writing.  Refer to the GNU Emacs General Public
  15 ;; License for full details.
  16
  17 ;; Everyone is granted permission to copy, modify and redistribute
  18 ;; GNU Emacs, but only under the conditions described in the
  19 ;; GNU Emacs General Public License.   A copy of this license is
  20 ;; supposed to have been given to you along with GNU Emacs so you
  21 ;; can know your rights and responsibilities.  It should be in a
  22 ;; file named COPYING.  Among other things, the copyright notice
  23 ;; and this notice must be preserved on all copies.
  24
  25 ;;; Commentary:
  26
  27 ;; This collection of functions implements the holiday features as described
  28 ;; in calendar.el.
  29
  30 ;; Comments, corrections, and improvements should be sent to
  31 ;;  Edward M. Reingold               Department of Computer Science
  32 ;;  (217) 333-6733                   University of Illinois at Urbana-Champaign
  33 ;;  reingold@cs.uiuc.edu             1304 West Springfield Avenue
  34 ;;                                   Urbana, Illinois 61801
  35
  36 ;; Technical details of all the calendrical calculations can be found in
  37 ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold,
  38 ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
  39 ;; pages 899-928.  ``Calendrical Calculations, Part II: Three Historical
  40 ;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
  41 ;; Report Number UIUCDCS-R-92-1743, Department of Computer Science,
  42 ;; University of Illinois, April, 1992.
  43
  44 ;; Hard copies of these two papers can be obtained by sending email to
  45 ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
  46 ;; the message BODY containing your mailing address (snail).
  47
  48 ;;; Code:
  49
  50 (require 'calendar)
  51
  52 (autoload 'calendar-holiday-function-solar-equinoxes-solstices "solar"
  53   "Date and time of equinoxes and solstices, if visible in the calendar window.
  54 Requires floating point."
  55   t)
  56
  57 (defun holidays (&optional arg)
  58   "Display the holidays for last month, this month, and next month.
  59 If called with an optional prefix argument, prompts for month and year.
  60
  61 This function is suitable for execution in a .emacs file."
  62   (interactive "P")
  63   (save-excursion
  64     (let* ((completion-ignore-case t)
  65            (date (calendar-current-date))
  66            (displayed-month
  67             (if arg
  68                 (cdr (assoc
  69                       (capitalize
  70                        (completing-read
  71                         "Month name: "
  72                         (mapcar 'list (append calendar-month-name-array nil))
  73                         nil t))
  74                       (calendar-make-alist calendar-month-name-array)))
  75               (extract-calendar-month date)))
  76            (displayed-year
  77             (if arg
  78                 (calendar-read
  79                  "Year (>0): "
  80                  '(lambda (x) (> x 0))
  81                  (int-to-string
  82                   (extract-calendar-year (calendar-current-date))))
  83               (extract-calendar-year date))))
  84       (list-calendar-holidays))))
  85
  86 (defun check-calendar-holidays (date)
  87   "Check the list of holidays for any that occur on DATE.
  88 The value returned is a list of strings of relevant holiday descriptions.
  89 The holidays are those in the list calendar-holidays."
  90   (let* ((displayed-month (extract-calendar-month date))
  91          (displayed-year (extract-calendar-year date))
  92          (h (calendar-holiday-list))
  93          (holiday-list))
  94     (while h
  95       (if (calendar-date-equal date (car (car h)))
  96           (setq holiday-list (append holiday-list (cdr (car h)))))
  97       (setq h (cdr h)))
  98     holiday-list))
  99
 100 (defun calendar-cursor-holidays ()
 101   "Find holidays for the date specified by the cursor in the calendar window."
 102   (interactive)
 103   (message "Checking holidays...")
 104   (let* ((date (or (calendar-cursor-to-date)
 105                    (error "Cursor is not on a date!")))
 106          (date-string (calendar-date-string date))
 107          (holiday-list (check-calendar-holidays date))
 108          (holiday-string (mapconcat 'identity holiday-list ";  "))
 109          (msg (format "%s:  %s" date-string holiday-string)))
 110     (if (not holiday-list)
 111         (message "No holidays known for %s" date-string)
 112       (if (<= (length msg) (screen-width))
 113           (message msg)
 114         (set-buffer (get-buffer-create holiday-buffer))
 115         (setq buffer-read-only nil)
 116         (calendar-set-mode-line date-string)
 117         (erase-buffer)
 118         (insert (mapconcat 'identity holiday-list "\n"))
 119         (goto-char (point-min))
 120         (set-buffer-modified-p nil)
 121         (setq buffer-read-only t)
 122         (display-buffer holiday-buffer)
 123         (message "Checking holidays...done")))))
 124
 125 (defun mark-calendar-holidays ()
 126   "Mark notable days in the calendar window."
 127   (interactive)
 128   (setq mark-holidays-in-calendar t)
 129   (message "Marking holidays...")
 130   (let ((holiday-list (calendar-holiday-list)))
 131     (while holiday-list
 132       (mark-visible-calendar-date
 133        (car (car holiday-list)) calendar-holiday-marker)
 134       (setq holiday-list (cdr holiday-list))))
 135   (message "Marking holidays...done"))
 136
 137 (defun list-calendar-holidays ()
 138   "Create a buffer containing the holidays for the current calendar window.
 139 The holidays are those in the list calendar-notable-days.  Returns t if any
 140 holidays are found, nil if not."
 141   (interactive)
 142   (message "Looking up holidays...")
 143   (let ((holiday-list (calendar-holiday-list))
 144         (m1 displayed-month)
 145         (y1 displayed-year)
 146         (m2 displayed-month)
 147         (y2 displayed-year))
 148     (if (not holiday-list)
 149         (progn
 150           (message "Looking up holidays...none found")
 151           nil)
 152       (set-buffer (get-buffer-create holiday-buffer))
 153       (setq buffer-read-only nil)
 154       (increment-calendar-month m1 y1 -1)
 155       (increment-calendar-month m2 y2 1)
 156       (calendar-set-mode-line
 157             (format "Notable Dates from %s, %d to %s, %d%%-"
 158                     (calendar-month-name m1) y1 (calendar-month-name m2) y2))
 159       (erase-buffer)
 160       (insert
 161        (mapconcat
 162         '(lambda (x) (concat (calendar-date-string (car x))
 163                              ": " (car (cdr x))))
 164         holiday-list "\n"))
 165       (goto-char (point-min))
 166       (set-buffer-modified-p nil)
 167       (setq buffer-read-only t)
 168       (display-buffer holiday-buffer)
 169       (message "Looking up holidays...done")
 170       t)))
 171
 172 (defun calendar-holiday-list ()
 173   "Form the list of holidays that occur on dates in the calendar window.
 174 The holidays are those in the list calendar-holidays."
 175   (let ((p calendar-holidays)
 176         (holiday-list))
 177     (while p
 178       (let* ((function-name
 179               (intern (format "calendar-holiday-function-%s" (car (car p)))))
 180              (holidays
 181               (condition-case nil
 182                   (if (cdr (car p));; optional arguments
 183                       (funcall function-name (cdr (car p)))
 184                     (funcall function-name))
 185                 (error
 186                  (beep)
 187                  (message "Bad holiday list item: %s" (car p))
 188                  (sleep-for 2)))))
 189         (if holidays
 190             (setq holiday-list (append holidays holiday-list))))
 191       (setq p (cdr p)))
 192     (setq holiday-list (sort holiday-list 'calendar-date-compare))))
 193
 194 ;; Below are the functions that calculate the dates of holidays; these
 195 ;; are called by the funcall in the function calendar-holiday-list.  If you
 196 ;; write other such functions, be sure to imitate the style used below,
 197 ;; including the evaluation of each element in the list that constitutes
 198 ;; the argument to the function.  If you don't do this evaluation, the
 199 ;; list calendar-holidays cannot contain expressions (as, for example, in
 200 ;; the entry for the Islamic new year.)  Also remember that each function
 201 ;; must return a list of items of the form ((month day year) string);
 202 ;; the date (month day year) should be visible in the calendar window.
 203
 204 (defun calendar-holiday-function-fixed (x)
 205   "Returns the corresponding Gregorian date, if visible in the window, to
 206 (month day) where month is (car X) and day is (car (cdr X)).  If it is
 207 visible, the value returned is the list (((month day year) string)) where
 208 string is (car (nthcdr 2 X)).  Returns nil if it is not visible in the
 209 current calendar window."
 210   (let* ((month (eval (car x)))
 211          (day (eval (car (cdr x))))
 212          (string (eval (car (nthcdr 2 x))))
 213          (m displayed-month)
 214          (y displayed-year))
 215     (increment-calendar-month m y (- 11 month))
 216     (if (> m 9)
 217       (list (list (list month day y) string)))))
 218
 219 (defun calendar-holiday-function-float (x)
 220   "Returns the corresponding Gregorian date, if visible in the window, to the
 221 n-th occurrence (negative counts from the end of the month) of dayname in
 222 month where month is (car X), dayname is (car (cdr X)), and n is
 223 (car (nthcdr 2 X)).  If it is visible, the value returned is the list
 224 (((month day year) string)) where string is (car (nthcdr 3 X)).
 225 Returns nil if it is not visible in the current calendar window."
 226   (let* ((month (eval (car x)))
 227          (dayname (eval (car (cdr x))))
 228          (n (eval (car (nthcdr 2 x))))
 229          (string (eval (car (nthcdr 3 x))))
 230          (m displayed-month)
 231          (y displayed-year))
 232     (increment-calendar-month m y (- 11 month))
 233     (if (> m 9)
 234       (list (list (calendar-nth-named-day n dayname month y) string)))))
 235
 236 (defun calendar-holiday-function-julian (x)
 237   "Returns the corresponding Gregorian date, if visible in the window, to the
 238 Julian date (month day) where month is (car X) and day is (car (cdr X)).
 239 If it is visible, the value returned is the list (((month day year) string))
 240 where string is (car (nthcdr 2 X)).  Returns nil if it is not visible in the
 241 current calendar window."
 242   (let* ((month (eval (car x)))
 243          (day (eval (car (cdr x))))
 244          (string (eval (car (nthcdr 2 x))))
 245          (m1 displayed-month)
 246          (y1 displayed-year)
 247          (m2 displayed-month)
 248          (y2 displayed-year)
 249          (year))
 250     (increment-calendar-month m1 y1 -1)
 251     (increment-calendar-month m2 y2 1)
 252     (let* ((start-date (calendar-absolute-from-gregorian
 253                         (list m1 1 y1)))
 254            (end-date (calendar-absolute-from-gregorian
 255                       (list m2 (calendar-last-day-of-month m2 y2) y2)))
 256            (julian-start (calendar-julian-from-absolute start-date))
 257            (julian-end (calendar-julian-from-absolute end-date))
 258            (julian-y1 (extract-calendar-year julian-start))
 259            (julian-y2 (extract-calendar-year julian-end)))
 260       (setq year (if (< 10 month) julian-y1 julian-y2))
 261       (let ((date (calendar-gregorian-from-absolute
 262                    (calendar-absolute-from-julian
 263                     (list month day year)))))
 264         (if (calendar-date-is-visible-p date)
 265             (list (list date string)))))))
 266
 267 (defun calendar-holiday-function-islamic (x)
 268   "Returns the corresponding Gregorian date, if visible in the window, to the
 269 Islamic date (month day) where month is (car X) and day is (car (cdr X)).
 270 If it is visible, the value returned is the list (((month day year) string))
 271 where string is (car (nthcdr 2 X)).  Returns nil if it is not visible in
 272 the current calendar window."
 273   (let* ((month (eval (car x)))
 274          (day (eval (car (cdr x))))
 275          (string (eval (car (nthcdr 2 x))))
 276          (islamic-date (calendar-islamic-from-absolute
 277                         (calendar-absolute-from-gregorian
 278                          (list displayed-month 15 displayed-year))))
 279          (m (extract-calendar-month islamic-date))
 280          (y (extract-calendar-year islamic-date))
 281         (date))
 282     (if (< m 1)
 283         nil;;   Islamic calendar doesn't apply.
 284       (increment-calendar-month m y (- 10 month))
 285       (if (> m 7);;  Islamic date might be visible
 286           (let ((date (calendar-gregorian-from-absolute
 287                        (calendar-absolute-from-islamic (list month day y)))))
 288             (if (calendar-date-is-visible-p date)
 289                 (list (list date string))))))))
 290
 291 (defun calendar-holiday-function-hebrew (x)
 292   "Returns the corresponding Gregorian date, if visible in the window, to the
 293 Hebrew date (month day) where month is (car X) and day is (car (cdr X)).
 294 If it is visible, the value returned is the list (((month day year) string))
 295 where string is (car (nthcdr 2 X)).  Returns nil if it is not visible in
 296 the current calendar window."
 297   (let* ((month (eval (car x)))
 298          (day (eval (car (cdr x))))
 299          (string (eval (car (nthcdr 2 x)))))
 300     (if (memq displayed-month;;  This test is only to speed things up a bit;
 301               (list          ;;  it works fine without the test too.
 302                (if (< 11 month) (- month 11) (+ month 1))
 303                (if (< 10 month) (- month 10) (+ month 2))
 304                (if (<  9 month) (- month  9) (+ month 3))
 305                (if (<  8 month) (- month  8) (+ month 4))
 306                (if (<  7 month) (- month  7) (+ month 5))))
 307         (let ((m1 displayed-month)
 308               (y1 displayed-year)
 309               (m2 displayed-month)
 310               (y2 displayed-year)
 311               (year))
 312           (increment-calendar-month m1 y1 -1)
 313           (increment-calendar-month m2 y2 1)
 314           (let* ((start-date (calendar-absolute-from-gregorian
 315                               (list m1 1 y1)))
 316                  (end-date (calendar-absolute-from-gregorian
 317                             (list m2 (calendar-last-day-of-month m2 y2) y2)))
 318                  (hebrew-start (calendar-hebrew-from-absolute start-date))
 319                  (hebrew-end (calendar-hebrew-from-absolute end-date))
 320                  (hebrew-y1 (extract-calendar-year hebrew-start))
 321                  (hebrew-y2 (extract-calendar-year hebrew-end)))
 322             (setq year (if (< 6 month) hebrew-y2 hebrew-y1))
 323             (let ((date (calendar-gregorian-from-absolute
 324                          (calendar-absolute-from-hebrew
 325                           (list month day year)))))
 326               (if (calendar-date-is-visible-p date)
 327                   (list (list date string)))))))))
 328
 329 (defun calendar-holiday-function-if (x)
 330   "Conditional holiday for dates in the calendar window.
 331 The boolean condition is (car X).  If t, the holiday (car (cdr X)) is
 332 checked.  If nil, the holiday (car (cdr (cdr X))), if there, is checked."
 333   (let* ((boolean (eval (car x)))
 334          (h (if boolean (car (cdr x)) (car (cdr (cdr x))))))
 335     (if h
 336      (let* ((function-name
 337               (intern (format "calendar-holiday-function-%s" (car h))))
 338             (holidays
 339               (if (cdr h);; optional arguments
 340                   (funcall function-name (cdr h))
 341                 (funcall function-name))))
 342        holidays))))
 343
 344 (defun calendar-holiday-function-sexp (x)
 345   "Sexp holiday for dates in the calendar window.
 346 The sexp (in `year') is (car X).  If the sexp evals to a date visible in the
 347 calendar window, the holiday (car (cdr X)) is on that date.  If the sexp evals
 348 to nil, or if the date is not visible, there is no holiday."
 349   (let ((m displayed-month)
 350         (y displayed-year))
 351     (increment-calendar-month m y -1)
 352     (filter-visible-calendar-holidays
 353      (append
 354       (let ((year y))
 355         (list (list (eval (car x)) (eval (car (cdr x))))))
 356       (let ((year (1+ y)))
 357         (list (list (eval (car x)) (eval (car (cdr x))))))))))
 358
 359 (defun calendar-holiday-function-advent ()
 360   "Date of Advent, if visible in calendar window."
 361   (let ((year displayed-year)
 362         (month displayed-month))
 363     (increment-calendar-month month year -1)
 364     (let ((advent (calendar-gregorian-from-absolute
 365                    (calendar-dayname-on-or-before 0
 366                     (calendar-absolute-from-gregorian
 367                      (list 12 3 year))))))
 368       (if (calendar-date-is-visible-p advent)
 369           (list (list advent "Advent"))))))
 370
 371 (defun calendar-holiday-function-easter-etc ()
 372   "List of dates related to Easter, as visible in calendar window."
 373  (if (and (> displayed-month 5) (not all-christian-calendar-holidays))
 374      nil;; Ash Wednesday, Good Friday, and Easter are not visible.
 375    (let* ((century (1+ (/ displayed-year 100)))
 376           (shifted-epact        ;; Age of moon for April 5...
 377            (% (+ 14 (* 11 (% displayed-year 19));;     ...by Nicaean rule
 378                  (-           ;; ...corrected for the Gregorian century rule
 379                   (/ (* 3 century) 4))
 380                  (/    ;; ...corrected for Metonic cycle inaccuracy.
 381                   (+ 5 (* 8 century)) 25)
 382                  (* 30 century));;              Keeps value positive.
 383               30))
 384           (adjusted-epact       ;;  Adjust for 29.5 day month.
 385            (if (or (= shifted-epact 0)
 386                    (and (= shifted-epact 1) (< 10 (% displayed-year 19))))
 387                (1+ shifted-epact)
 388              shifted-epact))
 389           (paschal-moon       ;; Day after the full moon on or after March 21.
 390            (- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
 391               adjusted-epact))
 392           (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))
 393           (mandatory
 394            (list
 395             (list (calendar-gregorian-from-absolute abs-easter)
 396                   "Easter Sunday")
 397             (list (calendar-gregorian-from-absolute (- abs-easter 2))
 398                   "Good Friday")
 399             (list (calendar-gregorian-from-absolute (- abs-easter 46))
 400                   "Ash Wednesday")))
 401           (optional
 402            (list
 403             (list (calendar-gregorian-from-absolute (- abs-easter 63))
 404                   "Septuagesima Sunday")
 405             (list (calendar-gregorian-from-absolute (- abs-easter 56))
 406                   "Sexagesima Sunday")
 407             (list (calendar-gregorian-from-absolute (- abs-easter 49))
 408                   "Shrove Sunday")
 409             (list (calendar-gregorian-from-absolute (- abs-easter 48))
 410                   "Shrove Monday")
 411             (list (calendar-gregorian-from-absolute (- abs-easter 47))
 412                   "Shrove Tuesday")
 413             (list (calendar-gregorian-from-absolute (- abs-easter 14))
 414                   "Passion Sunday")
 415             (list (calendar-gregorian-from-absolute (- abs-easter 7))
 416                   "Palm Sunday")
 417             (list (calendar-gregorian-from-absolute (- abs-easter 3))
 418                   "Maundy Thursday")
 419             (list (calendar-gregorian-from-absolute (+ abs-easter 35))
 420                   "Rogation Sunday")
 421             (list (calendar-gregorian-from-absolute (+ abs-easter 39))
 422                   "Ascension Sunday")
 423             (list (calendar-gregorian-from-absolute (+ abs-easter 49))
 424                   "Pentecost (Whitsunday)")
 425             (list (calendar-gregorian-from-absolute (+ abs-easter 50))
 426                   "Whitmunday")
 427             (list (calendar-gregorian-from-absolute (+ abs-easter 56))
 428                   "Trinity Sunday")
 429             (list (calendar-gregorian-from-absolute (+ abs-easter 60))
 430                   "Corpus Christi")))
 431           (output-list
 432            (filter-visible-calendar-holidays mandatory)))
 433      (if all-christian-calendar-holidays
 434          (setq output-list
 435                (append
 436                 (filter-visible-calendar-holidays optional)
 437                 output-list)))
 438      output-list)))
 439
 440 (defun calendar-holiday-function-greek-orthodox-easter ()
 441   "Date of Easter according to the rule of the Council of Nicaea, if visible
 442 in the calendar window."
 443   (let ((m displayed-month)
 444         (y displayed-year))
 445     (increment-calendar-month m y 1)
 446     (let* ((julian-year
 447             (extract-calendar-year
 448              (calendar-julian-from-absolute
 449               (calendar-absolute-from-gregorian
 450                (list m (calendar-last-day-of-month m y) y)))))
 451            (shifted-epact ;; Age of moon for April 5.
 452             (% (+ 14
 453                   (* 11 (% julian-year 19)))
 454                30))
 455            (paschal-moon  ;; Day after full moon on or after March 21.
 456             (- (calendar-absolute-from-julian (list 4 19 julian-year))
 457                shifted-epact))
 458            (nicaean-easter;; Sunday following the Paschal moon
 459             (calendar-gregorian-from-absolute
 460              (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))))
 461       (if (calendar-date-is-visible-p nicaean-easter)
 462           (list (list nicaean-easter "Pascha (Greek Orthodox Easter)"))))))
 463
 464 (defun calendar-holiday-function-rosh-hashanah-etc ()
 465   "List of dates related to Rosh Hashanah, as visible in calendar window."
 466   (if (or (< displayed-month 8)
 467           (> displayed-month 11))
 468       nil;; None of the dates is visible
 469     (let* ((abs-r-h (calendar-absolute-from-hebrew
 470                       (list 7 1 (+ displayed-year 3761))))
 471             (mandatory
 472              (list
 473               (list (calendar-gregorian-from-absolute abs-r-h)
 474                     (format "Rosh HaShanah %d" (+ 3761 displayed-year)))
 475               (list (calendar-gregorian-from-absolute (+ abs-r-h 9))
 476                     "Yom Kippur")
 477               (list (calendar-gregorian-from-absolute (+ abs-r-h 14))
 478                     "Sukkot")
 479               (list (calendar-gregorian-from-absolute (+ abs-r-h 21))
 480                     "Shemini Atzeret")
 481               (list (calendar-gregorian-from-absolute (+ abs-r-h 22))
 482                     "Simchat Torah")))
 483            (optional
 484             (list
 485              (list (calendar-gregorian-from-absolute
 486                     (calendar-dayname-on-or-before 6 (- abs-r-h 4)))
 487                    "Selichot (night)")
 488              (list (calendar-gregorian-from-absolute (1- abs-r-h))
 489                    "Erev Rosh HaShannah")
 490              (list (calendar-gregorian-from-absolute (1+ abs-r-h))
 491                    "Rosh HaShanah (second day)")
 492              (list (calendar-gregorian-from-absolute
 493                     (if (= (% abs-r-h 7) 4) (+ abs-r-h 3) (+ abs-r-h 2)))
 494                    "Tzom Gedaliah")
 495              (list (calendar-gregorian-from-absolute
 496                     (calendar-dayname-on-or-before 6 (+ 7 abs-r-h)))
 497                    "Shabbat Shuvah")
 498              (list (calendar-gregorian-from-absolute (+ abs-r-h 8))
 499                    "Erev Yom Kippur")
 500              (list (calendar-gregorian-from-absolute (+ abs-r-h 13))
 501                    "Erev Sukkot")
 502              (list (calendar-gregorian-from-absolute (+ abs-r-h 15))
 503                    "Sukkot (second day)")
 504              (list (calendar-gregorian-from-absolute (+ abs-r-h 16))
 505                    "Hol Hamoed Sukkot (first day)")
 506              (list (calendar-gregorian-from-absolute (+ abs-r-h 17))
 507                    "Hol Hamoed Sukkot (second day)")
 508              (list (calendar-gregorian-from-absolute (+ abs-r-h 18))
 509                    "Hol Hamoed Sukkot (third day)")
 510              (list (calendar-gregorian-from-absolute (+ abs-r-h 19))
 511                    "Hol Hamoed Sukkot (fourth day)")
 512              (list (calendar-gregorian-from-absolute (+ abs-r-h 20))
 513                    "Hoshannah Rabbah")))
 514             (output-list
 515              (filter-visible-calendar-holidays mandatory)))
 516       (if all-hebrew-calendar-holidays
 517           (setq output-list
 518                 (append
 519                  (filter-visible-calendar-holidays optional)
 520                  output-list)))
 521       output-list)))
 522
 523 (defun calendar-holiday-function-hanukkah ()
 524   "List of dates related to Hanukkah, as visible in calendar window."
 525     (if (memq displayed-month;;  This test is only to speed things up a bit;
 526               '(10 11 12 1 2));; it works fine without the test too.
 527         (let ((m displayed-month)
 528               (y displayed-year))
 529           (increment-calendar-month m y 1)
 530           (let* ((h-y (extract-calendar-year
 531                          (calendar-hebrew-from-absolute
 532                           (calendar-absolute-from-gregorian
 533                            (list m (calendar-last-day-of-month m y) y)))))
 534                  (abs-h (calendar-absolute-from-hebrew (list 9 25 h-y))))
 535             (filter-visible-calendar-holidays
 536              (list
 537               (list (calendar-gregorian-from-absolute (1- abs-h))
 538                     "Erev Hanukkah")
 539               (list (calendar-gregorian-from-absolute abs-h)
 540                     "Hanukkah (first day)")
 541               (list (calendar-gregorian-from-absolute (1+ abs-h))
 542                     "Hanukkah (second day)")
 543               (list (calendar-gregorian-from-absolute (+ abs-h 2))
 544                     "Hanukkah (third day)")
 545               (list (calendar-gregorian-from-absolute (+ abs-h 3))
 546                     "Hanukkah (fourth day)")
 547               (list (calendar-gregorian-from-absolute (+ abs-h 4))
 548                     "Hanukkah (fifth day)")
 549               (list (calendar-gregorian-from-absolute (+ abs-h 5))
 550                     "Hanukkah (sixth day)")
 551               (list (calendar-gregorian-from-absolute (+ abs-h 6))
 552                     "Hanukkah (seventh day)")
 553               (list (calendar-gregorian-from-absolute (+ abs-h 7))
 554                     "Hanukkah (eighth day)")))))))
 555
 556 (defun calendar-holiday-function-passover-etc ()
 557   "List of dates related to Passover, as visible in calendar window."
 558  (if (< 7 displayed-month)
 559       nil;; None of the dates is visible
 560     (let* ((abs-p (calendar-absolute-from-hebrew
 561                       (list 1 15 (+ displayed-year 3760))))
 562            (mandatory
 563             (list
 564              (list (calendar-gregorian-from-absolute abs-p)
 565                    "Passover")
 566              (list (calendar-gregorian-from-absolute (+ abs-p 50))
 567                    "Shavuot")))
 568            (optional
 569             (list
 570              (list (calendar-gregorian-from-absolute
 571                     (calendar-dayname-on-or-before 6 (- abs-p 43)))
 572                    "Shabbat Shekalim")
 573              (list (calendar-gregorian-from-absolute
 574                     (calendar-dayname-on-or-before 6 (- abs-p 30)))
 575                    "Shabbat Zachor")
 576              (list (calendar-gregorian-from-absolute
 577                     (if (= (% abs-p 7) 2) (- abs-p 33) (- abs-p 31)))
 578                    "Fast of Esther")
 579              (list (calendar-gregorian-from-absolute (- abs-p 31))
 580                    "Erev Purim")
 581              (list (calendar-gregorian-from-absolute (- abs-p 30))
 582                    "Purim")
 583              (list (calendar-gregorian-from-absolute
 584                     (if (zerop (% abs-p 7)) (- abs-p 28) (- abs-p 29)))
 585                    "Shushan Purim")
 586              (list (calendar-gregorian-from-absolute
 587                     (- (calendar-dayname-on-or-before 6 (- abs-p 14)) 7))
 588                    "Shabbat Parah")
 589              (list (calendar-gregorian-from-absolute
 590                     (calendar-dayname-on-or-before 6 (- abs-p 14)))
 591                    "Shabbat HaHodesh")
 592              (list (calendar-gregorian-from-absolute
 593                     (calendar-dayname-on-or-before 6 (1- abs-p)))
 594                    "Shabbat HaGadol")
 595              (list (calendar-gregorian-from-absolute (1- abs-p))
 596                    "Erev Passover")
 597              (list (calendar-gregorian-from-absolute (1+ abs-p))
 598                    "Passover (second day)")
 599              (list (calendar-gregorian-from-absolute (+ abs-p 2))
 600                    "Hol Hamoed Passover (first day)")
 601              (list (calendar-gregorian-from-absolute (+ abs-p 3))
 602                    "Hol Hamoed Passover (second day)")
 603              (list (calendar-gregorian-from-absolute (+ abs-p 4))
 604                    "Hol Hamoed Passover (third day)")
 605              (list (calendar-gregorian-from-absolute (+ abs-p 5))
 606                    "Hol Hamoed Passover (fourth day)")
 607              (list (calendar-gregorian-from-absolute (+ abs-p 6))
 608                    "Passover (seventh day)")
 609              (list (calendar-gregorian-from-absolute (+ abs-p 7))
 610                    "Passover (eighth day)")
 611              (list (calendar-gregorian-from-absolute (+ abs-p 12))
 612                    "Yom HaShoah")
 613              (list (calendar-gregorian-from-absolute
 614                     (if (zerop (% abs-p 7))
 615                         (+ abs-p 18)
 616                       (if (= (% abs-p 7) 6)
 617                           (+ abs-p 19)
 618                         (+ abs-p 20))))
 619                    "Yom HaAtzma'ut")
 620              (list (calendar-gregorian-from-absolute (+ abs-p 33))
 621                    "Lag BaOmer")
 622              (list (calendar-gregorian-from-absolute (+ abs-p 43))
 623                    "Yom Yerushalim")
 624              (list (calendar-gregorian-from-absolute (+ abs-p 49))
 625                    "Erev Shavuot")
 626              (list (calendar-gregorian-from-absolute (+ abs-p 51))
 627                    "Shavuot (second day)")))
 628            (output-list
 629              (filter-visible-calendar-holidays mandatory)))
 630       (if all-hebrew-calendar-holidays
 631           (setq output-list
 632                 (append
 633                  (filter-visible-calendar-holidays optional)
 634                  output-list)))
 635       output-list)))
 636
 637 (defun calendar-holiday-function-tisha-b-av-etc ()
 638   "List of dates around Tisha B'Av, as visible in calendar window."
 639   (if (or (< displayed-month 5)
 640           (> displayed-month 9))
 641       nil;; None of the dates is visible
 642     (let* ((abs-t-a (calendar-absolute-from-hebrew
 643                       (list 5 9 (+ displayed-year 3760)))))
 644
 645       (filter-visible-calendar-holidays
 646        (list
 647         (list (calendar-gregorian-from-absolute
 648                (if (= (% abs-t-a 7) 6) (- abs-t-a 20) (- abs-t-a 21)))
 649               "Tzom Tammuz")
 650         (list (calendar-gregorian-from-absolute
 651                (calendar-dayname-on-or-before 6 abs-t-a))
 652               "Shabbat Hazon")
 653         (list (calendar-gregorian-from-absolute
 654                (if (= (% abs-t-a 7) 6) (1+ abs-t-a) abs-t-a))
 655               "Tisha B'Av")
 656         (list (calendar-gregorian-from-absolute
 657                (calendar-dayname-on-or-before 6 (+ abs-t-a 7)))
 658               "Shabbat Nahamu"))))))
 659
 660 (defun filter-visible-calendar-holidays (l)
 661   "Return a list of all visible holidays of those on L."
 662   (let ((visible)
 663         (p l))
 664     (while p
 665       (if (calendar-date-is-visible-p (car (car p)))
 666           (setq visible (append (list (car p)) visible)))
 667       (setq p (cdr p)))
 668     visible))
 669
 670 (provide 'holidays)
 671
 672 ;;; holidays.el ends here