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, 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
  11 ;; GNU Emacs is distributed in the hope that it will be useful,
  12 ;; but WITHOUT ANY WARRANTY.  No author or distributor
  13 ;; accepts responsibility to anyone for the consequences of using it
  14 ;; or for whether it serves any particular purpose or works at all,
  15 ;; unless he says so in writing.  Refer to the GNU Emacs General Public
  16 ;; License for full details.
  17
  18 ;; Everyone is granted permission to copy, modify and redistribute
  19 ;; GNU Emacs, but only under the conditions described in the
  20 ;; GNU Emacs General Public License.   A copy of this license is
  21 ;; supposed to have been given to you along with GNU Emacs so you
  22 ;; can know your rights and responsibilities.  It should be in a
  23 ;; file named COPYING.  Among other things, the copyright notice
  24 ;; and this notice must be preserved on all copies.
  25
  26 ;;; Commentary:
  27
  28 ;; This collection of functions implements the holiday features as described
  29 ;; in calendar.el.
  30
  31 ;; Comments, corrections, and improvements should be sent to
  32 ;;  Edward M. Reingold               Department of Computer Science
  33 ;;  (217) 333-6733                   University of Illinois at Urbana-Champaign
  34 ;;  reingold@cs.uiuc.edu             1304 West Springfield Avenue
  35 ;;                                   Urbana, Illinois 61801
  36
  37 ;; Technical details of all the calendrical calculations can be found in
  38 ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold,
  39 ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
  40 ;; pages 899-928.  ``Calendrical Calculations, Part II: Three Historical
  41 ;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
  42 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
  43 ;; pages 383-404.
  44
  45 ;; Hard copies of these two papers can be obtained by sending email to
  46 ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
  47 ;; the message BODY containing your mailing address (snail).
  48
  49 ;;; Code:
  50
  51 (require 'calendar)
  52
  53 (autoload 'solar-equinoxes-solstices "solar"
  54   "Date and time of equinoxes and solstices, if visible in the calendar window.
  55 Requires floating point."
  56   t)
  57
  58 (defun holidays (&optional arg)
  59   "Display the holidays for last month, this month, and next month.
  60 If called with an optional prefix argument, prompts for month and year.
  61
  62 This function is suitable for execution in a .emacs file."
  63   (interactive "P")
  64   (save-excursion
  65     (let* ((completion-ignore-case t)
  66            (date (calendar-current-date))
  67            (displayed-month
  68             (if arg
  69                 (cdr (assoc
  70                       (capitalize
  71                        (completing-read
  72                         "Month name: "
  73                         (mapcar 'list (append calendar-month-name-array nil))
  74                         nil t))
  75                       (calendar-make-alist calendar-month-name-array)))
  76               (extract-calendar-month date)))
  77            (displayed-year
  78             (if arg
  79                 (calendar-read
  80                  "Year (>0): "
  81                  '(lambda (x) (> x 0))
  82                  (int-to-string
  83                   (extract-calendar-year (calendar-current-date))))
  84               (extract-calendar-year date))))
  85       (list-calendar-holidays))))
  86
  87 (defun check-calendar-holidays (date)
  88   "Check the list of holidays for any that occur on DATE.
  89 The value returned is a list of strings of relevant holiday descriptions.
  90 The holidays are those in the list calendar-holidays."
  91   (let* ((displayed-month (extract-calendar-month date))
  92          (displayed-year (extract-calendar-year date))
  93          (h (calendar-holiday-list))
  94          (holiday-list))
  95     (while h
  96       (if (calendar-date-equal date (car (car h)))
  97           (setq holiday-list (append holiday-list (cdr (car h)))))
  98       (setq h (cdr h)))
  99     holiday-list))
 100
 101 (defun calendar-cursor-holidays ()
 102   "Find holidays for the date specified by the cursor in the calendar window."
 103   (interactive)
 104   (message "Checking holidays...")
 105   (let* ((date (calendar-cursor-to-date t))
 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) (frame-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        (if (= y1 y2)
 158            (format "Notable Dates from %s to %s, %d%%-"
 159                    (calendar-month-name m1) (calendar-month-name m2) y2)
 160          (format "Notable Dates from %s, %d to %s, %d%%-"
 161                  (calendar-month-name m1) y1 (calendar-month-name m2) y2)))
 162       (erase-buffer)
 163       (insert
 164        (mapconcat
 165         '(lambda (x) (concat (calendar-date-string (car x))
 166                              ": " (car (cdr x))))
 167         holiday-list "\n"))
 168       (goto-char (point-min))
 169       (set-buffer-modified-p nil)
 170       (setq buffer-read-only t)
 171       (display-buffer holiday-buffer)
 172       (message "Looking up holidays...done")
 173       t)))
 174
 175 (defun calendar-holiday-list ()
 176   "Form the list of holidays that occur on dates in the calendar window.
 177 The holidays are those in the list calendar-holidays."
 178   (let ((p calendar-holidays)
 179         (holiday-list))
 180     (while p
 181       (let* ((holidays
 182               (if calendar-debug-sexp
 183                   (let ((stack-trace-on-error t))
 184                     (eval (car p)))
 185                 (condition-case nil
 186                     (eval (car p))
 187                   (error (beep)
 188                          (message "Bad holiday list item: %s" (car p))
 189                          (sleep-for 2))))))
 190         (if holidays
 191             (setq holiday-list (append holidays holiday-list))))
 192       (setq p (cdr p)))
 193     (setq holiday-list (sort holiday-list 'calendar-date-compare))))
 194
 195 ;; Below are the functions that calculate the dates of holidays; these
 196 ;; are eval'ed in the function calendar-holiday-list.  If you
 197 ;; write other such functions, be sure to imitate the style used below.
 198 ;; Remember that each function must return a list of items of the form
 199 ;; ((month day year) string) of VISIBLE dates in the calendar window.
 200
 201 (defun holiday-fixed (month day string)
 202   "Holiday on MONTH, DAY (Gregorian) called STRING.
 203 If MONTH, DAY is visible, the value returned is the list (((MONTH DAY year)
 204 STRING)).  Returns nil if it is not visible in the current calendar window."
 205   (let ((m displayed-month)
 206         (y displayed-year))
 207     (increment-calendar-month m y (- 11 month))
 208     (if (> m 9)
 209       (list (list (list month day y) string)))))
 210
 211 (defun holiday-float (month dayname n string &optional day)
 212   "Holiday on MONTH, DAYNAME (Nth occurrence, Gregorian) called STRING.
 213 If the Nth DAYNAME in MONTH is visible, the value returned is the list
 214 (((MONTH DAY year) STRING)).
 215
 216 If N<0, count backward from the end of MONTH.
 217
 218 An optional parameter DAY means the Nth DAYNAME after/before MONTH DAY.
 219
 220 Returns nil if it is not visible in the current calendar window."
 221   (let ((m displayed-month)
 222         (y displayed-year))
 223     (increment-calendar-month m y (- 11 month))
 224     (if (> m 9)
 225       (list (list (calendar-nth-named-day n dayname month y day) string)))))
 226
 227 (defun holiday-julian (month day string)
 228   "Holiday on MONTH, DAY  (Julian) called STRING.
 229 If MONTH, DAY (Julian) is visible, the value returned is corresponding
 230 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 231 nil if it is not visible in the current calendar window."
 232   (let ((m1 displayed-month)
 233         (y1 displayed-year)
 234         (m2 displayed-month)
 235         (y2 displayed-year)
 236         (year))
 237     (increment-calendar-month m1 y1 -1)
 238     (increment-calendar-month m2 y2 1)
 239     (let* ((start-date (calendar-absolute-from-gregorian
 240                         (list m1 1 y1)))
 241            (end-date (calendar-absolute-from-gregorian
 242                       (list m2 (calendar-last-day-of-month m2 y2) y2)))
 243            (julian-start (calendar-julian-from-absolute start-date))
 244            (julian-end (calendar-julian-from-absolute end-date))
 245            (julian-y1 (extract-calendar-year julian-start))
 246            (julian-y2 (extract-calendar-year julian-end)))
 247       (setq year (if (< 10 month) julian-y1 julian-y2))
 248       (let ((date (calendar-gregorian-from-absolute
 249                    (calendar-absolute-from-julian
 250                     (list month day year)))))
 251         (if (calendar-date-is-visible-p date)
 252             (list (list date string)))))))
 253
 254 (defun holiday-islamic (month day string)
 255   "Holiday on MONTH, DAY (Islamic) called STRING.
 256 If MONTH, DAY (Islamic) is visible, the value returned is corresponding
 257 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 258 nil if it is not visible in the current calendar window."
 259   (let* ((islamic-date (calendar-islamic-from-absolute
 260                         (calendar-absolute-from-gregorian
 261                          (list displayed-month 15 displayed-year))))
 262          (m (extract-calendar-month islamic-date))
 263          (y (extract-calendar-year islamic-date))
 264         (date))
 265     (if (< m 1)
 266         nil;;   Islamic calendar doesn't apply.
 267       (increment-calendar-month m y (- 10 month))
 268       (if (> m 7);;  Islamic date might be visible
 269           (let ((date (calendar-gregorian-from-absolute
 270                        (calendar-absolute-from-islamic (list month day y)))))
 271             (if (calendar-date-is-visible-p date)
 272                 (list (list date string))))))))
 273
 274 (defun holiday-hebrew (month day string)
 275   "Holiday on MONTH, DAY (Hebrew) called STRING.
 276 If MONTH, DAY (Hebrew) is visible, the value returned is corresponding
 277 Gregorian date in the form of the list (((month day year) STRING)).  Returns
 278 nil if it is not visible in the current calendar window."
 279   (if (memq displayed-month;;  This test is only to speed things up a bit;
 280             (list          ;;  it works fine without the test too.
 281              (if (< 11 month) (- month 11) (+ month 1))
 282              (if (< 10 month) (- month 10) (+ month 2))
 283              (if (<  9 month) (- month  9) (+ month 3))
 284              (if (<  8 month) (- month  8) (+ month 4))
 285              (if (<  7 month) (- month  7) (+ month 5))))
 286       (let ((m1 displayed-month)
 287             (y1 displayed-year)
 288             (m2 displayed-month)
 289             (y2 displayed-year)
 290             (year))
 291         (increment-calendar-month m1 y1 -1)
 292         (increment-calendar-month m2 y2 1)
 293         (let* ((start-date (calendar-absolute-from-gregorian
 294                             (list m1 1 y1)))
 295                (end-date (calendar-absolute-from-gregorian
 296                           (list m2 (calendar-last-day-of-month m2 y2) y2)))
 297                (hebrew-start (calendar-hebrew-from-absolute start-date))
 298                (hebrew-end (calendar-hebrew-from-absolute end-date))
 299                (hebrew-y1 (extract-calendar-year hebrew-start))
 300                (hebrew-y2 (extract-calendar-year hebrew-end)))
 301           (setq year (if (< 6 month) hebrew-y2 hebrew-y1))
 302           (let ((date (calendar-gregorian-from-absolute
 303                        (calendar-absolute-from-hebrew
 304                         (list month day year)))))
 305             (if (calendar-date-is-visible-p date)
 306                 (list (list date string))))))))
 307
 308 (defun holiday-sexp (sexp string)
 309   "Sexp holiday for dates in the calendar window.
 310 SEXP is an expression in variable `year' evaluates to `date'.
 311
 312 STRING is an expression in `date' that evaluates to the holiday description
 313 of `date'.
 314
 315 If `date' is visible in the calendar window, the holiday STRING is on that
 316 date.  If date is nil, or if the date is not visible, there is no holiday."
 317   (let ((m displayed-month)
 318         (y displayed-year))
 319     (increment-calendar-month m y -1)
 320     (filter-visible-calendar-holidays
 321      (append
 322       (let* ((year y)
 323              (date (eval sexp))
 324              (string (if date (eval string))))
 325         (list (list date string)))
 326       (let* ((year (1+ y))
 327              (date (eval sexp))
 328              (string (if date (eval string))))
 329         (list (list date string)))))))
 330
 331 (defun holiday-advent ()
 332   "Date of Advent, if visible in calendar window."
 333   (let ((year displayed-year)
 334         (month displayed-month))
 335     (increment-calendar-month month year -1)
 336     (let ((advent (calendar-gregorian-from-absolute
 337                    (calendar-dayname-on-or-before 0
 338                     (calendar-absolute-from-gregorian
 339                      (list 12 3 year))))))
 340       (if (calendar-date-is-visible-p advent)
 341           (list (list advent "Advent"))))))
 342
 343 (defun holiday-easter-etc ()
 344   "List of dates related to Easter, as visible in calendar window."
 345  (if (and (> displayed-month 5) (not all-christian-calendar-holidays))
 346      nil;; Ash Wednesday, Good Friday, and Easter are not visible.
 347    (let* ((century (1+ (/ displayed-year 100)))
 348           (shifted-epact        ;; Age of moon for April 5...
 349            (% (+ 14 (* 11 (% displayed-year 19));;     ...by Nicaean rule
 350                  (-           ;; ...corrected for the Gregorian century rule
 351                   (/ (* 3 century) 4))
 352                  (/    ;; ...corrected for Metonic cycle inaccuracy.
 353                   (+ 5 (* 8 century)) 25)
 354                  (* 30 century));;              Keeps value positive.
 355               30))
 356           (adjusted-epact       ;;  Adjust for 29.5 day month.
 357            (if (or (= shifted-epact 0)
 358                    (and (= shifted-epact 1) (< 10 (% displayed-year 19))))
 359                (1+ shifted-epact)
 360              shifted-epact))
 361           (paschal-moon       ;; Day after the full moon on or after March 21.
 362            (- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
 363               adjusted-epact))
 364           (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))
 365           (mandatory
 366            (list
 367             (list (calendar-gregorian-from-absolute abs-easter)
 368                   "Easter Sunday")
 369             (list (calendar-gregorian-from-absolute (- abs-easter 2))
 370                   "Good Friday")
 371             (list (calendar-gregorian-from-absolute (- abs-easter 46))
 372                   "Ash Wednesday")))
 373           (optional
 374            (list
 375             (list (calendar-gregorian-from-absolute (- abs-easter 63))
 376                   "Septuagesima Sunday")
 377             (list (calendar-gregorian-from-absolute (- abs-easter 56))
 378                   "Sexagesima Sunday")
 379             (list (calendar-gregorian-from-absolute (- abs-easter 49))
 380                   "Shrove Sunday")
 381             (list (calendar-gregorian-from-absolute (- abs-easter 48))
 382                   "Shrove Monday")
 383             (list (calendar-gregorian-from-absolute (- abs-easter 47))
 384                   "Shrove Tuesday")
 385             (list (calendar-gregorian-from-absolute (- abs-easter 14))
 386                   "Passion Sunday")
 387             (list (calendar-gregorian-from-absolute (- abs-easter 7))
 388                   "Palm Sunday")
 389             (list (calendar-gregorian-from-absolute (- abs-easter 3))
 390                   "Maundy Thursday")
 391             (list (calendar-gregorian-from-absolute (+ abs-easter 35))
 392                   "Rogation Sunday")
 393             (list (calendar-gregorian-from-absolute (+ abs-easter 39))
 394                   "Ascension Day")
 395             (list (calendar-gregorian-from-absolute (+ abs-easter 49))
 396                   "Pentecost (Whitsunday)")
 397             (list (calendar-gregorian-from-absolute (+ abs-easter 50))
 398                   "Whitmunday")
 399             (list (calendar-gregorian-from-absolute (+ abs-easter 56))
 400                   "Trinity Sunday")
 401             (list (calendar-gregorian-from-absolute (+ abs-easter 60))
 402                   "Corpus Christi")))
 403           (output-list
 404            (filter-visible-calendar-holidays mandatory)))
 405      (if all-christian-calendar-holidays
 406          (setq output-list
 407                (append
 408                 (filter-visible-calendar-holidays optional)
 409                 output-list)))
 410      output-list)))
 411
 412 (defun holiday-greek-orthodox-easter ()
 413   "Date of Easter according to the rule of the Council of Nicaea."
 414   (let ((m displayed-month)
 415         (y displayed-year))
 416     (increment-calendar-month m y 1)
 417     (let* ((julian-year
 418             (extract-calendar-year
 419              (calendar-julian-from-absolute
 420               (calendar-absolute-from-gregorian
 421                (list m (calendar-last-day-of-month m y) y)))))
 422            (shifted-epact ;; Age of moon for April 5.
 423             (% (+ 14
 424                   (* 11 (% julian-year 19)))
 425                30))
 426            (paschal-moon  ;; Day after full moon on or after March 21.
 427             (- (calendar-absolute-from-julian (list 4 19 julian-year))
 428                shifted-epact))
 429            (nicaean-easter;; Sunday following the Paschal moon
 430             (calendar-gregorian-from-absolute
 431              (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))))
 432       (if (calendar-date-is-visible-p nicaean-easter)
 433           (list (list nicaean-easter "Pascha (Greek Orthodox Easter)"))))))
 434
 435 (defun holiday-rosh-hashanah-etc ()
 436   "List of dates related to Rosh Hashanah, as visible in calendar window."
 437   (if (or (< displayed-month 8)
 438           (> displayed-month 11))
 439       nil;; None of the dates is visible
 440     (let* ((abs-r-h (calendar-absolute-from-hebrew
 441                       (list 7 1 (+ displayed-year 3761))))
 442             (mandatory
 443              (list
 444               (list (calendar-gregorian-from-absolute abs-r-h)
 445                     (format "Rosh HaShanah %d" (+ 3761 displayed-year)))
 446               (list (calendar-gregorian-from-absolute (+ abs-r-h 9))
 447                     "Yom Kippur")
 448               (list (calendar-gregorian-from-absolute (+ abs-r-h 14))
 449                     "Sukkot")
 450               (list (calendar-gregorian-from-absolute (+ abs-r-h 21))
 451                     "Shemini Atzeret")
 452               (list (calendar-gregorian-from-absolute (+ abs-r-h 22))
 453                     "Simchat Torah")))
 454            (optional
 455             (list
 456              (list (calendar-gregorian-from-absolute
 457                     (calendar-dayname-on-or-before 6 (- abs-r-h 4)))
 458                    "Selichot (night)")
 459              (list (calendar-gregorian-from-absolute (1- abs-r-h))
 460                    "Erev Rosh HaShannah")
 461              (list (calendar-gregorian-from-absolute (1+ abs-r-h))
 462                    "Rosh HaShanah (second day)")
 463              (list (calendar-gregorian-from-absolute
 464                     (if (= (% abs-r-h 7) 4) (+ abs-r-h 3) (+ abs-r-h 2)))
 465                    "Tzom Gedaliah")
 466              (list (calendar-gregorian-from-absolute
 467                     (calendar-dayname-on-or-before 6 (+ 7 abs-r-h)))
 468                    "Shabbat Shuvah")
 469              (list (calendar-gregorian-from-absolute (+ abs-r-h 8))
 470                    "Erev Yom Kippur")
 471              (list (calendar-gregorian-from-absolute (+ abs-r-h 13))
 472                    "Erev Sukkot")
 473              (list (calendar-gregorian-from-absolute (+ abs-r-h 15))
 474                    "Sukkot (second day)")
 475              (list (calendar-gregorian-from-absolute (+ abs-r-h 16))
 476                    "Hol Hamoed Sukkot (first day)")
 477              (list (calendar-gregorian-from-absolute (+ abs-r-h 17))
 478                    "Hol Hamoed Sukkot (second day)")
 479              (list (calendar-gregorian-from-absolute (+ abs-r-h 18))
 480                    "Hol Hamoed Sukkot (third day)")
 481              (list (calendar-gregorian-from-absolute (+ abs-r-h 19))
 482                    "Hol Hamoed Sukkot (fourth day)")
 483              (list (calendar-gregorian-from-absolute (+ abs-r-h 20))
 484                    "Hoshannah Rabbah")))
 485             (output-list
 486              (filter-visible-calendar-holidays mandatory)))
 487       (if all-hebrew-calendar-holidays
 488           (setq output-list
 489                 (append
 490                  (filter-visible-calendar-holidays optional)
 491                  output-list)))
 492       output-list)))
 493
 494 (defun holiday-hanukkah ()
 495   "List of dates related to Hanukkah, as visible in calendar window."
 496     (if (memq displayed-month;;  This test is only to speed things up a bit;
 497               '(10 11 12 1 2));; it works fine without the test too.
 498         (let ((m displayed-month)
 499               (y displayed-year))
 500           (increment-calendar-month m y 1)
 501           (let* ((h-y (extract-calendar-year
 502                          (calendar-hebrew-from-absolute
 503                           (calendar-absolute-from-gregorian
 504                            (list m (calendar-last-day-of-month m y) y)))))
 505                  (abs-h (calendar-absolute-from-hebrew (list 9 25 h-y))))
 506             (filter-visible-calendar-holidays
 507              (list
 508               (list (calendar-gregorian-from-absolute (1- abs-h))
 509                     "Erev Hanukkah")
 510               (list (calendar-gregorian-from-absolute abs-h)
 511                     "Hanukkah (first day)")
 512               (list (calendar-gregorian-from-absolute (1+ abs-h))
 513                     "Hanukkah (second day)")
 514               (list (calendar-gregorian-from-absolute (+ abs-h 2))
 515                     "Hanukkah (third day)")
 516               (list (calendar-gregorian-from-absolute (+ abs-h 3))
 517                     "Hanukkah (fourth day)")
 518               (list (calendar-gregorian-from-absolute (+ abs-h 4))
 519                     "Hanukkah (fifth day)")
 520               (list (calendar-gregorian-from-absolute (+ abs-h 5))
 521                     "Hanukkah (sixth day)")
 522               (list (calendar-gregorian-from-absolute (+ abs-h 6))
 523                     "Hanukkah (seventh day)")
 524               (list (calendar-gregorian-from-absolute (+ abs-h 7))
 525                     "Hanukkah (eighth day)")))))))
 526
 527 (defun holiday-passover-etc ()
 528   "List of dates related to Passover, as visible in calendar window."
 529  (if (< 7 displayed-month)
 530       nil;; None of the dates is visible
 531     (let* ((abs-p (calendar-absolute-from-hebrew
 532                       (list 1 15 (+ displayed-year 3760))))
 533            (mandatory
 534             (list
 535              (list (calendar-gregorian-from-absolute abs-p)
 536                    "Passover")
 537              (list (calendar-gregorian-from-absolute (+ abs-p 50))
 538                    "Shavuot")))
 539            (optional
 540             (list
 541              (list (calendar-gregorian-from-absolute
 542                     (calendar-dayname-on-or-before 6 (- abs-p 43)))
 543                    "Shabbat Shekalim")
 544              (list (calendar-gregorian-from-absolute
 545                     (calendar-dayname-on-or-before 6 (- abs-p 30)))
 546                    "Shabbat Zachor")
 547              (list (calendar-gregorian-from-absolute
 548                     (if (= (% abs-p 7) 2) (- abs-p 33) (- abs-p 31)))
 549                    "Fast of Esther")
 550              (list (calendar-gregorian-from-absolute (- abs-p 31))
 551                    "Erev Purim")
 552              (list (calendar-gregorian-from-absolute (- abs-p 30))
 553                    "Purim")
 554              (list (calendar-gregorian-from-absolute
 555                     (if (zerop (% abs-p 7)) (- abs-p 28) (- abs-p 29)))
 556                    "Shushan Purim")
 557              (list (calendar-gregorian-from-absolute
 558                     (- (calendar-dayname-on-or-before 6 (- abs-p 14)) 7))
 559                    "Shabbat Parah")
 560              (list (calendar-gregorian-from-absolute
 561                     (calendar-dayname-on-or-before 6 (- abs-p 14)))
 562                    "Shabbat HaHodesh")
 563              (list (calendar-gregorian-from-absolute
 564                     (calendar-dayname-on-or-before 6 (1- abs-p)))
 565                    "Shabbat HaGadol")
 566              (list (calendar-gregorian-from-absolute (1- abs-p))
 567                    "Erev Passover")
 568              (list (calendar-gregorian-from-absolute (1+ abs-p))
 569                    "Passover (second day)")
 570              (list (calendar-gregorian-from-absolute (+ abs-p 2))
 571                    "Hol Hamoed Passover (first day)")
 572              (list (calendar-gregorian-from-absolute (+ abs-p 3))
 573                    "Hol Hamoed Passover (second day)")
 574              (list (calendar-gregorian-from-absolute (+ abs-p 4))
 575                    "Hol Hamoed Passover (third day)")
 576              (list (calendar-gregorian-from-absolute (+ abs-p 5))
 577                    "Hol Hamoed Passover (fourth day)")
 578              (list (calendar-gregorian-from-absolute (+ abs-p 6))
 579                    "Passover (seventh day)")
 580              (list (calendar-gregorian-from-absolute (+ abs-p 7))
 581                    "Passover (eighth day)")
 582              (list (calendar-gregorian-from-absolute (+ abs-p 12))
 583                    "Yom HaShoah")
 584              (list (calendar-gregorian-from-absolute
 585                     (if (zerop (% abs-p 7))
 586                         (+ abs-p 18)
 587                       (if (= (% abs-p 7) 6)
 588                           (+ abs-p 19)
 589                         (+ abs-p 20))))
 590                    "Yom HaAtzma'ut")
 591              (list (calendar-gregorian-from-absolute (+ abs-p 33))
 592                    "Lag BaOmer")
 593              (list (calendar-gregorian-from-absolute (+ abs-p 43))
 594                    "Yom Yerushalim")
 595              (list (calendar-gregorian-from-absolute (+ abs-p 49))
 596                    "Erev Shavuot")
 597              (list (calendar-gregorian-from-absolute (+ abs-p 51))
 598                    "Shavuot (second day)")))
 599            (output-list
 600              (filter-visible-calendar-holidays mandatory)))
 601       (if all-hebrew-calendar-holidays
 602           (setq output-list
 603                 (append
 604                  (filter-visible-calendar-holidays optional)
 605                  output-list)))
 606       output-list)))
 607
 608 (defun holiday-tisha-b-av-etc ()
 609   "List of dates around Tisha B'Av, as visible in calendar window."
 610   (if (or (< displayed-month 5)
 611           (> displayed-month 9))
 612       nil;; None of the dates is visible
 613     (let* ((abs-t-a (calendar-absolute-from-hebrew
 614                       (list 5 9 (+ displayed-year 3760)))))
 615
 616       (filter-visible-calendar-holidays
 617        (list
 618         (list (calendar-gregorian-from-absolute
 619                (if (= (% abs-t-a 7) 6) (- abs-t-a 20) (- abs-t-a 21)))
 620               "Tzom Tammuz")
 621         (list (calendar-gregorian-from-absolute
 622                (calendar-dayname-on-or-before 6 abs-t-a))
 623               "Shabbat Hazon")
 624         (list (calendar-gregorian-from-absolute
 625                (if (= (% abs-t-a 7) 6) (1+ abs-t-a) abs-t-a))
 626               "Tisha B'Av")
 627         (list (calendar-gregorian-from-absolute
 628                (calendar-dayname-on-or-before 6 (+ abs-t-a 7)))
 629               "Shabbat Nahamu"))))))
 630
 631 (defun filter-visible-calendar-holidays (l)
 632   "Return a list of all visible holidays of those on L."
 633   (let ((visible)
 634         (p l))
 635     (while p
 636       (and (car (car p))
 637            (calendar-date-is-visible-p (car (car p)))
 638            (setq visible (append (list (car p)) visible)))
 639       (setq p (cdr p)))
 640     visible))
 641
 642 (provide 'holidays)
 643
 644 ;;; holidays.el ends here