lisp/calendar/holidays.el

   1 ;;; holidays.el --- holiday functions for the calendar package
   2
   3 ;;; Copyright (C) 1989, 1990, 1992, 1993 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 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.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  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
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; This collection of functions implements the holiday features as described
  27 ;; in calendar.el.
  28
  29 ;; Comments, corrections, and improvements should be sent to
  30 ;;  Edward M. Reingold               Department of Computer Science
  31 ;;  (217) 333-6733                   University of Illinois at Urbana-Champaign
  32 ;;  reingold@cs.uiuc.edu             1304 West Springfield Avenue
  33 ;;                                   Urbana, Illinois 61801
  34
  35 ;; Technical details of all the calendrical calculations can be found in
  36 ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold,
  37 ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
  38 ;; pages 899-928.  ``Calendrical Calculations, Part II: Three Historical
  39 ;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
  40 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
  41 ;; pages 383-404.
  42
  43 ;; Hard copies of these two papers can be obtained by sending email to
  44 ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
  45 ;; the message BODY containing your mailing address (snail).
  46
  47 ;;; Code:
  48
  49 (require 'calendar)
  50
  51 (autoload 'solar-equinoxes-solstices "solar"
  52   "Date and time of equinoxes and solstices, if visible in the calendar window.
  53 Requires floating point."
  54   t)
  55
  56 (defun holidays (&optional arg)
  57   "Display the holidays for last month, this month, and next month.
  58 If called with an optional prefix argument, prompts for month and year.
  59
  60 This function is suitable for execution in a .emacs file."
  61   (interactive "P")
  62   (save-excursion
  63     (let* ((completion-ignore-case t)
  64            (date (calendar-current-date))
  65            (displayed-month
  66             (if arg
  67                 (cdr (assoc
  68                       (capitalize
  69                        (completing-read
  70                         "Month name: "
  71                         (mapcar 'list (append calendar-month-name-array nil))
  72                         nil t))
  73                       (calendar-make-alist calendar-month-name-array)))
  74               (extract-calendar-month date)))
  75            (displayed-year
  76             (if arg
  77                 (calendar-read
  78                  "Year (>0): "
  79                  '(lambda (x) (> x 0))
  80                  (int-to-string
  81                   (extract-calendar-year (calendar-current-date))))
  82               (extract-calendar-year date))))
  83       (list-calendar-holidays))))
  84
  85 (defun check-calendar-holidays (date)
  86   "Check the list of holidays for any that occur on DATE.
  87 The value returned is a list of strings of relevant holiday descriptions.
  88 The holidays are those in the list calendar-holidays."
  89   (let* ((displayed-month (extract-calendar-month date))
  90          (displayed-year (extract-calendar-year date))
  91          (h (calendar-holiday-list))
  92          (holiday-list))
  93     (while h
  94       (if (calendar-date-equal date (car (car h)))
  95           (setq holiday-list (append holiday-list (cdr (car h)))))
  96       (setq h (cdr h)))
  97     holiday-list))
  98
  99 (defun calendar-cursor-holidays ()
 100   "Find holidays for the date specified by the cursor in the calendar window."
 101   (interactive)
 102   (message "Checking holidays...")
 103   (let* ((date (calendar-cursor-to-date t))
 104          (date-string (calendar-date-string date))
 105          (holiday-list (check-calendar-holidays date))
 106          (holiday-string (mapconcat 'identity holiday-list ";  "))
 107          (msg (format "%s:  %s" date-string holiday-string)))
 108     (if (not holiday-list)
 109         (message "No holidays known for %s" date-string)
 110       (if (<= (length msg) (frame-width))
 111           (message msg)
 112         (set-buffer (get-buffer-create holiday-buffer))
 113         (setq buffer-read-only nil)
 114         (calendar-set-mode-line date-string)
 115         (erase-buffer)
 116         (insert (mapconcat 'identity holiday-list "\n"))
 117         (goto-char (point-min))
 118         (set-buffer-modified-p nil)
 119         (setq buffer-read-only t)
 120         (display-buffer holiday-buffer)
 121         (message "Checking holidays...done")))))
 122
 123 (defun mark-calendar-holidays ()
 124   "Mark notable days in the calendar window."
 125   (interactive)
 126   (setq mark-holidays-in-calendar t)
 127   (message "Marking holidays...")
 128   (let ((holiday-list (calendar-holiday-list)))
 129     (while holiday-list
 130       (mark-visible-calendar-date
 131        (car (car holiday-list)) calendar-holiday-marker)
 132       (setq holiday-list (cdr holiday-list))))
 133   (message "Marking holidays...done"))
 134
 135 (defun list-calendar-holidays ()
 136   "Create a buffer containing the holidays for the current calendar window.
 137 The holidays are those in the list calendar-notable-days.  Returns t if any
 138 holidays are found, nil if not."
 139   (interactive)
 140   (message "Looking up holidays...")
 141   (let ((holiday-list (calendar-holiday-list))
 142         (m1 displayed-month)
 143         (y1 displayed-year)
 144         (m2 displayed-month)
 145         (y2 displayed-year))
 146     (if (not holiday-list)
 147         (progn
 148           (message "Looking up holidays...none found")
 149           nil)
 150       (set-buffer (get-buffer-create holiday-buffer))
 151       (setq buffer-read-only nil)
 152       (increment-calendar-month m1 y1 -1)
 153       (increment-calendar-month m2 y2 1)
 154       (calendar-set-mode-line
 155        (if (= y1 y2)
 156            (format "Notable Dates from %s to %s, %d%%-"
 157                    (calendar-month-name m1) (calendar-month-name m2) y2)
 158          (format "Notable Dates from %s, %d to %s, %d%%-"
 159                  (calendar-month-name m1) y1 (calendar-month-name m2) y2)))
 160       (erase-buffer)
 161       (insert
 162        (mapconcat
 163         '(lambda (x) (concat (calendar-date-string (car x))
 164                              ": " (car (cdr x))))
 165         holiday-list "\n"))
 166       (goto-char (point-min))
 167       (set-buffer-modified-p nil)
 168       (setq buffer-read-only t)
 169       (display-buffer holiday-buffer)
 170       (message "Looking up holidays...done")
 171       t)))
 172
 173 (defun calendar-holiday-list ()
 174   "Form the list of holidays that occur on dates in the calendar window.
 175 The holidays are those in the list calendar-holidays."
 176   (let ((p calendar-holidays)
 177         (holiday-list))
 178     (while p
 179       (let* ((holidays
 180               (if calendar-debug-sexp
 181                   (let ((stack-trace-on-error t))
 182                     (eval (car p)))
 183                 (condition-case nil
 184                     (eval (car p))
 185                   (error (beep)
 186                          (message "Bad holiday list item: %s" (car p))
 187                          (sleep-for 2))))))
 188         (if holidays
 189             (setq holiday-list (append holidays holiday-list))))
 190       (setq p (cdr p)))
 191     (setq holiday-list (sort holiday-list 'calendar-date-compare))))
 192
 193 ;; Below are the functions that calculate the dates of holidays; these
 194 ;; are eval'ed in the function calendar-holiday-list.  If you
 195 ;; write other such functions, be sure to imitate the style used below.
 196 ;; Remember that each function must return a list of items of the form
 197 ;; ((month day year) string) of VISIBLE dates in the calendar window.
 198
 199 (defun holiday-fixed (month day string)
 200   "Holiday on MONTH, DAY (Gregorian) called STRING.
 201 If MONTH, DAY is visible, the value returned is the list (((MONTH DAY year)
 202 STRING)).  Returns nil if it is not visible in the current calendar window."
 203   (let ((m displayed-month)
 204         (y displayed-year))
 205     (increment-calendar-month m y (- 11 month))
 206     (if (> m 9)
 207       (list (list (list month day y) string)))))
 208
 209 (defun holiday-float (month dayname n string &optional day)
 210   "Holiday on MONTH, DAYNAME (Nth occurrence, Gregorian) called STRING.
 211 If the Nth DAYNAME in MONTH is visible, the value returned is the list
 212 (((MONTH DAY year) STRING)).
 213
 214 If N<0, count backward from the end of MONTH.
 215
 216 An optional parameter DAY means the Nth DAYNAME after/before MONTH DAY.
 217
 218 Returns nil if it is not visible in the current calendar window."
 219   (let ((m displayed-month)
 220         (y displayed-year))
 221     (increment-calendar-month m y (- 11 month))
 222     (if (> m 9)
 223       (list (list (calendar-nth-named-day n dayname month y day) string)))))
 224
 225 (defun holiday-julian (month day string)
 226   "Holiday on MONTH, DAY  (Julian) called STRING.
 227 If MONTH, DAY (Julian) is visible, the value returned is corresponding
 228 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 229 nil if it is not visible in the current calendar window."
 230   (let ((m1 displayed-month)
 231         (y1 displayed-year)
 232         (m2 displayed-month)
 233         (y2 displayed-year)
 234         (year))
 235     (increment-calendar-month m1 y1 -1)
 236     (increment-calendar-month m2 y2 1)
 237     (let* ((start-date (calendar-absolute-from-gregorian
 238                         (list m1 1 y1)))
 239            (end-date (calendar-absolute-from-gregorian
 240                       (list m2 (calendar-last-day-of-month m2 y2) y2)))
 241            (julian-start (calendar-julian-from-absolute start-date))
 242            (julian-end (calendar-julian-from-absolute end-date))
 243            (julian-y1 (extract-calendar-year julian-start))
 244            (julian-y2 (extract-calendar-year julian-end)))
 245       (setq year (if (< 10 month) julian-y1 julian-y2))
 246       (let ((date (calendar-gregorian-from-absolute
 247                    (calendar-absolute-from-julian
 248                     (list month day year)))))
 249         (if (calendar-date-is-visible-p date)
 250             (list (list date string)))))))
 251
 252 (defun holiday-islamic (month day string)
 253   "Holiday on MONTH, DAY (Islamic) called STRING.
 254 If MONTH, DAY (Islamic) is visible, the value returned is corresponding
 255 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 256 nil if it is not visible in the current calendar window."
 257   (let* ((islamic-date (calendar-islamic-from-absolute
 258                         (calendar-absolute-from-gregorian
 259                          (list displayed-month 15 displayed-year))))
 260          (m (extract-calendar-month islamic-date))
 261          (y (extract-calendar-year islamic-date))
 262         (date))
 263     (if (< m 1)
 264         nil;;   Islamic calendar doesn't apply.
 265       (increment-calendar-month m y (- 10 month))
 266       (if (> m 7);;  Islamic date might be visible
 267           (let ((date (calendar-gregorian-from-absolute
 268                        (calendar-absolute-from-islamic (list month day y)))))
 269             (if (calendar-date-is-visible-p date)
 270                 (list (list date string))))))))
 271
 272 (defun holiday-hebrew (month day string)
 273   "Holiday on MONTH, DAY (Hebrew) called STRING.
 274 If MONTH, DAY (Hebrew) is visible, the value returned is corresponding
 275 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 276 nil if it is not visible in the current calendar window."
 277   (if (memq displayed-month;;  This test is only to speed things up a bit;
 278             (list          ;;  it works fine without the test too.
 279              (if (< 11 month) (- month 11) (+ month 1))
 280              (if (< 10 month) (- month 10) (+ month 2))
 281              (if (<  9 month) (- month  9) (+ month 3))
 282              (if (<  8 month) (- month  8) (+ month 4))
 283              (if (<  7 month) (- month  7) (+ month 5))))
 284       (let ((m1 displayed-month)
 285             (y1 displayed-year)
 286             (m2 displayed-month)
 287             (y2 displayed-year)
 288             (year))
 289         (increment-calendar-month m1 y1 -1)
 290         (increment-calendar-month m2 y2 1)
 291         (let* ((start-date (calendar-absolute-from-gregorian
 292                             (list m1 1 y1)))
 293                (end-date (calendar-absolute-from-gregorian
 294                           (list m2 (calendar-last-day-of-month m2 y2) y2)))
 295                (hebrew-start (calendar-hebrew-from-absolute start-date))
 296                (hebrew-end (calendar-hebrew-from-absolute end-date))
 297                (hebrew-y1 (extract-calendar-year hebrew-start))
 298                (hebrew-y2 (extract-calendar-year hebrew-end)))
 299           (setq year (if (< 6 month) hebrew-y2 hebrew-y1))
 300           (let ((date (calendar-gregorian-from-absolute
 301                        (calendar-absolute-from-hebrew
 302                         (list month day year)))))
 303             (if (calendar-date-is-visible-p date)
 304                 (list (list date string))))))))
 305
 306 (defun holiday-sexp (sexp string)
 307   "Sexp holiday for dates in the calendar window.
 308 SEXP is an expression in variable `year' evaluates to `date'.
 309
 310 STRING is an expression in `date' that evaluates to the holiday description
 311 of `date'.
 312
 313 If `date' is visible in the calendar window, the holiday STRING is on that
 314 date.  If date is nil, or if the date is not visible, there is no holiday."
 315   (let ((m displayed-month)
 316         (y displayed-year))
 317     (increment-calendar-month m y -1)
 318     (filter-visible-calendar-holidays
 319      (append
 320       (let* ((year y)
 321              (date (eval sexp))
 322              (string (if date (eval string))))
 323         (list (list date string)))
 324       (let* ((year (1+ y))
 325              (date (eval sexp))
 326              (string (if date (eval string))))
 327         (list (list date string)))))))
 328
 329 (defun holiday-advent ()
 330   "Date of Advent, if visible in calendar window."
 331   (let ((year displayed-year)
 332         (month displayed-month))
 333     (increment-calendar-month month year -1)
 334     (let ((advent (calendar-gregorian-from-absolute
 335                    (calendar-dayname-on-or-before 0
 336                     (calendar-absolute-from-gregorian
 337                      (list 12 3 year))))))
 338       (if (calendar-date-is-visible-p advent)
 339           (list (list advent "Advent"))))))
 340
 341 (defun holiday-easter-etc ()
 342   "List of dates related to Easter, as visible in calendar window."
 343  (if (and (> displayed-month 5) (not all-christian-calendar-holidays))
 344      nil;; Ash Wednesday, Good Friday, and Easter are not visible.
 345    (let* ((century (1+ (/ displayed-year 100)))
 346           (shifted-epact        ;; Age of moon for April 5...
 347            (% (+ 14 (* 11 (% displayed-year 19));;     ...by Nicaean rule
 348                  (-           ;; ...corrected for the Gregorian century rule
 349                   (/ (* 3 century) 4))
 350                  (/    ;; ...corrected for Metonic cycle inaccuracy.
 351                   (+ 5 (* 8 century)) 25)
 352                  (* 30 century));;              Keeps value positive.
 353               30))
 354           (adjusted-epact       ;;  Adjust for 29.5 day month.
 355            (if (or (= shifted-epact 0)
 356                    (and (= shifted-epact 1) (< 10 (% displayed-year 19))))
 357                (1+ shifted-epact)
 358              shifted-epact))
 359           (paschal-moon       ;; Day after the full moon on or after March 21.
 360            (- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
 361               adjusted-epact))
 362           (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))
 363           (mandatory
 364            (list
 365             (list (calendar-gregorian-from-absolute abs-easter)
 366                   "Easter Sunday")
 367             (list (calendar-gregorian-from-absolute (- abs-easter 2))
 368                   "Good Friday")
 369             (list (calendar-gregorian-from-absolute (- abs-easter 46))
 370                   "Ash Wednesday")))
 371           (optional
 372            (list
 373             (list (calendar-gregorian-from-absolute (- abs-easter 63))
 374                   "Septuagesima Sunday")
 375             (list (calendar-gregorian-from-absolute (- abs-easter 56))
 376                   "Sexagesima Sunday")
 377             (list (calendar-gregorian-from-absolute (- abs-easter 49))
 378                   "Shrove Sunday")
 379             (list (calendar-gregorian-from-absolute (- abs-easter 48))
 380                   "Shrove Monday")
 381             (list (calendar-gregorian-from-absolute (- abs-easter 47))
 382                   "Shrove Tuesday")
 383             (list (calendar-gregorian-from-absolute (- abs-easter 14))
 384                   "Passion Sunday")
 385             (list (calendar-gregorian-from-absolute (- abs-easter 7))
 386                   "Palm Sunday")
 387             (list (calendar-gregorian-from-absolute (- abs-easter 3))
 388                   "Maundy Thursday")
 389             (list (calendar-gregorian-from-absolute (+ abs-easter 35))
 390                   "Rogation Sunday")
 391             (list (calendar-gregorian-from-absolute (+ abs-easter 39))
 392                   "Ascension Day")
 393             (list (calendar-gregorian-from-absolute (+ abs-easter 49))
 394                   "Pentecost (Whitsunday)")
 395             (list (calendar-gregorian-from-absolute (+ abs-easter 50))
 396                   "Whitmunday")
 397             (list (calendar-gregorian-from-absolute (+ abs-easter 56))
 398                   "Trinity Sunday")
 399             (list (calendar-gregorian-from-absolute (+ abs-easter 60))
 400                   "Corpus Christi")))
 401           (output-list
 402            (filter-visible-calendar-holidays mandatory)))
 403      (if all-christian-calendar-holidays
 404          (setq output-list
 405                (append
 406                 (filter-visible-calendar-holidays optional)
 407                 output-list)))
 408      output-list)))
 409
 410 (defun holiday-greek-orthodox-easter ()
 411   "Date of Easter according to the rule of the Council of Nicaea."
 412   (let ((m displayed-month)
 413         (y displayed-year))
 414     (increment-calendar-month m y 1)
 415     (let* ((julian-year
 416             (extract-calendar-year
 417              (calendar-julian-from-absolute
 418               (calendar-absolute-from-gregorian
 419                (list m (calendar-last-day-of-month m y) y)))))
 420            (shifted-epact ;; Age of moon for April 5.
 421             (% (+ 14
 422                   (* 11 (% julian-year 19)))
 423                30))
 424            (paschal-moon  ;; Day after full moon on or after March 21.
 425             (- (calendar-absolute-from-julian (list 4 19 julian-year))
 426                shifted-epact))
 427            (nicaean-easter;; Sunday following the Paschal moon
 428             (calendar-gregorian-from-absolute
 429              (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))))
 430       (if (calendar-date-is-visible-p nicaean-easter)
 431           (list (list nicaean-easter "Pascha (Greek Orthodox Easter)"))))))
 432
 433 (defun holiday-rosh-hashanah-etc ()
 434   "List of dates related to Rosh Hashanah, as visible in calendar window."
 435   (if (or (< displayed-month 8)
 436           (> displayed-month 11))
 437       nil;; None of the dates is visible
 438     (let* ((abs-r-h (calendar-absolute-from-hebrew
 439                       (list 7 1 (+ displayed-year 3761))))
 440             (mandatory
 441              (list
 442               (list (calendar-gregorian-from-absolute abs-r-h)
 443                     (format "Rosh HaShanah %d" (+ 3761 displayed-year)))
 444               (list (calendar-gregorian-from-absolute (+ abs-r-h 9))
 445                     "Yom Kippur")
 446               (list (calendar-gregorian-from-absolute (+ abs-r-h 14))
 447                     "Sukkot")
 448               (list (calendar-gregorian-from-absolute (+ abs-r-h 21))
 449                     "Shemini Atzeret")
 450               (list (calendar-gregorian-from-absolute (+ abs-r-h 22))
 451                     "Simchat Torah")))
 452            (optional
 453             (list
 454              (list (calendar-gregorian-from-absolute
 455                     (calendar-dayname-on-or-before 6 (- abs-r-h 4)))
 456                    "Selichot (night)")
 457              (list (calendar-gregorian-from-absolute (1- abs-r-h))
 458                    "Erev Rosh HaShannah")
 459              (list (calendar-gregorian-from-absolute (1+ abs-r-h))
 460                    "Rosh HaShanah (second day)")
 461              (list (calendar-gregorian-from-absolute
 462                     (if (= (% abs-r-h 7) 4) (+ abs-r-h 3) (+ abs-r-h 2)))
 463                    "Tzom Gedaliah")
 464              (list (calendar-gregorian-from-absolute
 465                     (calendar-dayname-on-or-before 6 (+ 7 abs-r-h)))
 466                    "Shabbat Shuvah")
 467              (list (calendar-gregorian-from-absolute (+ abs-r-h 8))
 468                    "Erev Yom Kippur")
 469              (list (calendar-gregorian-from-absolute (+ abs-r-h 13))
 470                    "Erev Sukkot")
 471              (list (calendar-gregorian-from-absolute (+ abs-r-h 15))
 472                    "Sukkot (second day)")
 473              (list (calendar-gregorian-from-absolute (+ abs-r-h 16))
 474                    "Hol Hamoed Sukkot (first day)")
 475              (list (calendar-gregorian-from-absolute (+ abs-r-h 17))
 476                    "Hol Hamoed Sukkot (second day)")
 477              (list (calendar-gregorian-from-absolute (+ abs-r-h 18))
 478                    "Hol Hamoed Sukkot (third day)")
 479              (list (calendar-gregorian-from-absolute (+ abs-r-h 19))
 480                    "Hol Hamoed Sukkot (fourth day)")
 481              (list (calendar-gregorian-from-absolute (+ abs-r-h 20))
 482                    "Hoshannah Rabbah")))
 483             (output-list
 484              (filter-visible-calendar-holidays mandatory)))
 485       (if all-hebrew-calendar-holidays
 486           (setq output-list
 487                 (append
 488                  (filter-visible-calendar-holidays optional)
 489                  output-list)))
 490       output-list)))
 491
 492 (defun holiday-hanukkah ()
 493   "List of dates related to Hanukkah, as visible in calendar window."
 494     (if (memq displayed-month;;  This test is only to speed things up a bit;
 495               '(10 11 12 1 2));; it works fine without the test too.
 496         (let ((m displayed-month)
 497               (y displayed-year))
 498           (increment-calendar-month m y 1)
 499           (let* ((h-y (extract-calendar-year
 500                          (calendar-hebrew-from-absolute
 501                           (calendar-absolute-from-gregorian
 502                            (list m (calendar-last-day-of-month m y) y)))))
 503                  (abs-h (calendar-absolute-from-hebrew (list 9 25 h-y))))
 504             (filter-visible-calendar-holidays
 505              (list
 506               (list (calendar-gregorian-from-absolute (1- abs-h))
 507                     "Erev Hanukkah")
 508               (list (calendar-gregorian-from-absolute abs-h)
 509                     "Hanukkah (first day)")
 510               (list (calendar-gregorian-from-absolute (1+ abs-h))
 511                     "Hanukkah (second day)")
 512               (list (calendar-gregorian-from-absolute (+ abs-h 2))
 513                     "Hanukkah (third day)")
 514               (list (calendar-gregorian-from-absolute (+ abs-h 3))
 515                     "Hanukkah (fourth day)")
 516               (list (calendar-gregorian-from-absolute (+ abs-h 4))
 517                     "Hanukkah (fifth day)")
 518               (list (calendar-gregorian-from-absolute (+ abs-h 5))
 519                     "Hanukkah (sixth day)")
 520               (list (calendar-gregorian-from-absolute (+ abs-h 6))
 521                     "Hanukkah (seventh day)")
 522               (list (calendar-gregorian-from-absolute (+ abs-h 7))
 523                     "Hanukkah (eighth day)")))))))
 524
 525 (defun holiday-passover-etc ()
 526   "List of dates related to Passover, as visible in calendar window."
 527  (if (< 7 displayed-month)
 528       nil;; None of the dates is visible
 529     (let* ((abs-p (calendar-absolute-from-hebrew
 530                       (list 1 15 (+ displayed-year 3760))))
 531            (mandatory
 532             (list
 533              (list (calendar-gregorian-from-absolute abs-p)
 534                    "Passover")
 535              (list (calendar-gregorian-from-absolute (+ abs-p 50))
 536                    "Shavuot")))
 537            (optional
 538             (list
 539              (list (calendar-gregorian-from-absolute
 540                     (calendar-dayname-on-or-before 6 (- abs-p 43)))
 541                    "Shabbat Shekalim")
 542              (list (calendar-gregorian-from-absolute
 543                     (calendar-dayname-on-or-before 6 (- abs-p 30)))
 544                    "Shabbat Zachor")
 545              (list (calendar-gregorian-from-absolute
 546                     (if (= (% abs-p 7) 2) (- abs-p 33) (- abs-p 31)))
 547                    "Fast of Esther")
 548              (list (calendar-gregorian-from-absolute (- abs-p 31))
 549                    "Erev Purim")
 550              (list (calendar-gregorian-from-absolute (- abs-p 30))
 551                    "Purim")
 552              (list (calendar-gregorian-from-absolute
 553                     (if (zerop (% abs-p 7)) (- abs-p 28) (- abs-p 29)))
 554                    "Shushan Purim")
 555              (list (calendar-gregorian-from-absolute
 556                     (- (calendar-dayname-on-or-before 6 (- abs-p 14)) 7))
 557                    "Shabbat Parah")
 558              (list (calendar-gregorian-from-absolute
 559                     (calendar-dayname-on-or-before 6 (- abs-p 14)))
 560                    "Shabbat HaHodesh")
 561              (list (calendar-gregorian-from-absolute
 562                     (calendar-dayname-on-or-before 6 (1- abs-p)))
 563                    "Shabbat HaGadol")
 564              (list (calendar-gregorian-from-absolute (1- abs-p))
 565                    "Erev Passover")
 566              (list (calendar-gregorian-from-absolute (1+ abs-p))
 567                    "Passover (second day)")
 568              (list (calendar-gregorian-from-absolute (+ abs-p 2))
 569                    "Hol Hamoed Passover (first day)")
 570              (list (calendar-gregorian-from-absolute (+ abs-p 3))
 571                    "Hol Hamoed Passover (second day)")
 572              (list (calendar-gregorian-from-absolute (+ abs-p 4))
 573                    "Hol Hamoed Passover (third day)")
 574              (list (calendar-gregorian-from-absolute (+ abs-p 5))
 575                    "Hol Hamoed Passover (fourth day)")
 576              (list (calendar-gregorian-from-absolute (+ abs-p 6))
 577                    "Passover (seventh day)")
 578              (list (calendar-gregorian-from-absolute (+ abs-p 7))
 579                    "Passover (eighth day)")
 580              (list (calendar-gregorian-from-absolute (+ abs-p 12))
 581                    "Yom HaShoah")
 582              (list (calendar-gregorian-from-absolute
 583                     (if (zerop (% abs-p 7))
 584                         (+ abs-p 18)
 585                       (if (= (% abs-p 7) 6)
 586                           (+ abs-p 19)
 587                         (+ abs-p 20))))
 588                    "Yom HaAtzma'ut")
 589              (list (calendar-gregorian-from-absolute (+ abs-p 33))
 590                    "Lag BaOmer")
 591              (list (calendar-gregorian-from-absolute (+ abs-p 43))
 592                    "Yom Yerushalim")
 593              (list (calendar-gregorian-from-absolute (+ abs-p 49))
 594                    "Erev Shavuot")
 595              (list (calendar-gregorian-from-absolute (+ abs-p 51))
 596                    "Shavuot (second day)")))
 597            (output-list
 598              (filter-visible-calendar-holidays mandatory)))
 599       (if all-hebrew-calendar-holidays
 600           (setq output-list
 601                 (append
 602                  (filter-visible-calendar-holidays optional)
 603                  output-list)))
 604       output-list)))
 605
 606 (defun holiday-tisha-b-av-etc ()
 607   "List of dates around Tisha B'Av, as visible in calendar window."
 608   (if (or (< displayed-month 5)
 609           (> displayed-month 9))
 610       nil;; None of the dates is visible
 611     (let* ((abs-t-a (calendar-absolute-from-hebrew
 612                       (list 5 9 (+ displayed-year 3760)))))
 613
 614       (filter-visible-calendar-holidays
 615        (list
 616         (list (calendar-gregorian-from-absolute
 617                (if (= (% abs-t-a 7) 6) (- abs-t-a 20) (- abs-t-a 21)))
 618               "Tzom Tammuz")
 619         (list (calendar-gregorian-from-absolute
 620                (calendar-dayname-on-or-before 6 abs-t-a))
 621               "Shabbat Hazon")
 622         (list (calendar-gregorian-from-absolute
 623                (if (= (% abs-t-a 7) 6) (1+ abs-t-a) abs-t-a))
 624               "Tisha B'Av")
 625         (list (calendar-gregorian-from-absolute
 626                (calendar-dayname-on-or-before 6 (+ abs-t-a 7)))
 627               "Shabbat Nahamu"))))))
 628
 629 (defun filter-visible-calendar-holidays (l)
 630   "Return a list of all visible holidays of those on L."
 631   (let ((visible)
 632         (p l))
 633     (while p
 634       (and (car (car p))
 635            (calendar-date-is-visible-p (car (car p)))
 636            (setq visible (append (list (car p)) visible)))
 637       (setq p (cdr p)))
 638     visible))
 639
 640 (provide 'holidays)
 641
 642 ;;; holidays.el ends here