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, 1994 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 the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  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 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
  42 ;; pages 383-404.
  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 'holiday-julian "cal-julian"
  53   "Holiday on MONTH, DAY  (Julian) called STRING."
  54   t)
  55
  56 (autoload 'holiday-hebrew "cal-hebrew"
  57   "Holiday on MONTH, DAY (Hebrew) called STRING."
  58   t)
  59
  60 (autoload 'holiday-rosh-hashanah-etc "cal-hebrew"
  61   "List of dates related to Rosh Hashanah, as visible in calendar window."
  62   t)
  63
  64 (autoload 'holiday-hanukkah "cal-hebrew"
  65   "List of dates related to Hanukkah, as visible in calendar window."
  66   t)
  67
  68 (autoload 'holiday-passover-etc "cal-hebrew"
  69   "List of dates related to Passover, as visible in calendar window."
  70   t)
  71
  72 (autoload 'holiday-tisha-b-av-etc "cal-hebrew"
  73   "List of dates around Tisha B'Av, as visible in calendar window."
  74   t)
  75
  76 (autoload 'holiday-islamic "cal-islam"
  77   "Holiday on MONTH, DAY (Islamic) called STRING."
  78   t)
  79
  80 (autoload 'holiday-chinese-new-year "cal-china"
  81   "Date of Chinese New Year."
  82   t)
  83
  84 (autoload 'solar-equinoxes-solstices "solar"
  85   "Date and time of equinoxes and solstices, if visible in the calendar window.
  86 Requires floating point."
  87   t)
  88
  89 (defun holidays (&optional arg)
  90   "Display the holidays for last month, this month, and next month.
  91 If called with an optional prefix argument, prompts for month and year.
  92
  93 This function is suitable for execution in a .emacs file."
  94   (interactive "P")
  95   (save-excursion
  96     (let* ((completion-ignore-case t)
  97            (date (if arg
  98                      (calendar-read-date t)
  99                    (calendar-current-date)))
 100            (displayed-month (extract-calendar-month date))
 101            (displayed-year (extract-calendar-year date)))
 102       (list-calendar-holidays))))
 103
 104 (defun list-holidays (y1 y2 &optional l label)
 105   "Display holidays for years Y1 to Y2 (inclusive).
 106
 107 The optional list of holidays L defaults to `calendar-holidays'.  See the
 108 documentation for that variable for a description of holiday lists.
 109
 110 The optional LABEL is used to label the buffer created."
 111   (interactive
 112    (let* ((start-year (calendar-read
 113                        "Starting year of holidays (>0): "
 114                        '(lambda (x) (> x 0))
 115                        (int-to-string (extract-calendar-year
 116                                        (calendar-current-date)))))
 117           (end-year (calendar-read
 118                        (format "Ending year (inclusive) of holidays (>=%s): "
 119                                start-year)
 120                        '(lambda (x) (>= x start-year))
 121                        (int-to-string start-year)))
 122           (completion-ignore-case t)
 123           (lists
 124            (list
 125             (cons "All" calendar-holidays)
 126             (if (fboundp 'atan)
 127                 (cons "Equinoxes/Solstices"
 128                       (list (list 'solar-equinoxes-solstices))))
 129             (if general-holidays (cons "General" general-holidays))
 130             (if local-holidays (cons "Local" local-holidays))
 131             (if other-holidays (cons "Other" other-holidays))
 132             (if christian-holidays (cons "Christian" christian-holidays))
 133             (if hebrew-holidays (cons "Hebrew" hebrew-holidays))
 134             (if islamic-holidays (cons "Islamic" islamic-holidays))
 135             (if oriental-holidays (cons "Oriental" oriental-holidays))
 136             (if solar-holidays (cons "Solar" solar-holidays))
 137             (cons "Ask" nil)))
 138           (choice (capitalize
 139                    (completing-read "List (TAB for choices): " lists nil t)))
 140           (which (if (string-equal choice "Ask")
 141                      (eval (read-variable "Enter list name: "))
 142                    (cdr (assoc choice lists))))
 143           (name (if (string-equal choice "Equinoxes/Solstices")
 144                     choice
 145                   (if (string-equal choice "Ask")
 146                       "Holidays"
 147                     (format "%s Holidays" choice)))))
 148      (list start-year end-year which name)))
 149   (message "Computing holidays...")
 150   (let* ((holiday-buffer "*Holidays*")
 151          (calendar-holidays (if l l calendar-holidays))
 152          (title (if label label "Holidays"))
 153          (holiday-list nil)
 154          (s (calendar-absolute-from-gregorian (list 2 1 y1)))
 155          (e (calendar-absolute-from-gregorian (list 11 1 y2)))
 156          (d s)
 157          (never t)
 158          (displayed-month 2)
 159          (displayed-year y1))
 160     (while (or never (<= d e))
 161       (setq holiday-list (append holiday-list (calendar-holiday-list)))
 162       (setq never nil)
 163       (increment-calendar-month displayed-month displayed-year 3)
 164       (setq d (calendar-absolute-from-gregorian
 165                (list displayed-month 1 displayed-year))))
 166     (set-buffer (get-buffer-create holiday-buffer))
 167     (setq buffer-read-only nil)
 168     (calendar-set-mode-line
 169      (if (= y1 y2)
 170          (format "%s for %s" label y1)
 171        (format "%s for %s-%s" label y1 y2)))
 172     (erase-buffer)
 173     (goto-char (point-min))
 174     (insert
 175      (mapconcat
 176       '(lambda (x) (concat (calendar-date-string (car x)) ": " (car (cdr x))))
 177       holiday-list "\n"))
 178     (goto-char (point-min))
 179     (set-buffer-modified-p nil)
 180     (setq buffer-read-only t)
 181     (display-buffer holiday-buffer)
 182     (message "Computing holidays...done")))
 183
 184 (defun check-calendar-holidays (date)
 185   "Check the list of holidays for any that occur on DATE.
 186 The value returned is a list of strings of relevant holiday descriptions.
 187 The holidays are those in the list calendar-holidays."
 188   (let* ((displayed-month (extract-calendar-month date))
 189          (displayed-year (extract-calendar-year date))
 190          (h (calendar-holiday-list))
 191          (holiday-list))
 192     (while h
 193       (if (calendar-date-equal date (car (car h)))
 194           (setq holiday-list (append holiday-list (cdr (car h)))))
 195       (setq h (cdr h)))
 196     holiday-list))
 197
 198 (defun calendar-cursor-holidays ()
 199   "Find holidays for the date specified by the cursor in the calendar window."
 200   (interactive)
 201   (message "Checking holidays...")
 202   (let* ((date (calendar-cursor-to-date t))
 203          (date-string (calendar-date-string date))
 204          (holiday-list (check-calendar-holidays date))
 205          (holiday-string (mapconcat 'identity holiday-list ";  "))
 206          (msg (format "%s:  %s" date-string holiday-string)))
 207     (if (not holiday-list)
 208         (message "No holidays known for %s" date-string)
 209       (if (<= (length msg) (frame-width))
 210           (message "%s" msg)
 211         (set-buffer (get-buffer-create holiday-buffer))
 212         (setq buffer-read-only nil)
 213         (calendar-set-mode-line date-string)
 214         (erase-buffer)
 215         (insert (mapconcat 'identity holiday-list "\n"))
 216         (goto-char (point-min))
 217         (set-buffer-modified-p nil)
 218         (setq buffer-read-only t)
 219         (display-buffer holiday-buffer)
 220         (message "Checking holidays...done")))))
 221
 222 (defun mark-calendar-holidays ()
 223   "Mark notable days in the calendar window."
 224   (interactive)
 225   (setq mark-holidays-in-calendar t)
 226   (message "Marking holidays...")
 227   (let ((holiday-list (calendar-holiday-list)))
 228     (while holiday-list
 229       (mark-visible-calendar-date
 230        (car (car holiday-list)) calendar-holiday-marker)
 231       (setq holiday-list (cdr holiday-list))))
 232   (message "Marking holidays...done"))
 233
 234 (defun list-calendar-holidays ()
 235   "Create a buffer containing the holidays for the current calendar window.
 236 The holidays are those in the list calendar-notable-days.  Returns t if any
 237 holidays are found, nil if not."
 238   (interactive)
 239   (message "Looking up holidays...")
 240   (let ((holiday-list (calendar-holiday-list))
 241         (m1 displayed-month)
 242         (y1 displayed-year)
 243         (m2 displayed-month)
 244         (y2 displayed-year))
 245     (if (not holiday-list)
 246         (progn
 247           (message "Looking up holidays...none found")
 248           nil)
 249       (set-buffer (get-buffer-create holiday-buffer))
 250       (setq buffer-read-only nil)
 251       (increment-calendar-month m1 y1 -1)
 252       (increment-calendar-month m2 y2 1)
 253       (calendar-set-mode-line
 254        (if (= y1 y2)
 255            (format "Notable Dates from %s to %s, %d%%-"
 256                    (calendar-month-name m1) (calendar-month-name m2) y2)
 257          (format "Notable Dates from %s, %d to %s, %d%%-"
 258                  (calendar-month-name m1) y1 (calendar-month-name m2) y2)))
 259       (erase-buffer)
 260       (insert
 261        (mapconcat
 262         '(lambda (x) (concat (calendar-date-string (car x))
 263                              ": " (car (cdr x))))
 264         holiday-list "\n"))
 265       (goto-char (point-min))
 266       (set-buffer-modified-p nil)
 267       (setq buffer-read-only t)
 268       (display-buffer holiday-buffer)
 269       (message "Looking up holidays...done")
 270       t)))
 271
 272 (defun calendar-holiday-list ()
 273   "Form the list of holidays that occur on dates in the calendar window.
 274 The holidays are those in the list calendar-holidays."
 275   (let ((p calendar-holidays)
 276         (holiday-list))
 277     (while p
 278       (let* ((holidays
 279               (if calendar-debug-sexp
 280                   (let ((stack-trace-on-error t))
 281                     (eval (car p)))
 282                 (condition-case nil
 283                     (eval (car p))
 284                   (error (beep)
 285                          (message "Bad holiday list item: %s" (car p))
 286                          (sleep-for 2))))))
 287         (if holidays
 288             (setq holiday-list (append holidays holiday-list))))
 289       (setq p (cdr p)))
 290     (setq holiday-list (sort holiday-list 'calendar-date-compare))))
 291
 292 ;; Below are the functions that calculate the dates of holidays; these
 293 ;; are eval'ed in the function calendar-holiday-list.  If you
 294 ;; write other such functions, be sure to imitate the style used below.
 295 ;; Remember that each function must return a list of items of the form
 296 ;; ((month day year) string) of VISIBLE dates in the calendar window.
 297
 298 (defun holiday-fixed (month day string)
 299   "Holiday on MONTH, DAY (Gregorian) called STRING.
 300 If MONTH, DAY is visible, the value returned is the list (((MONTH DAY year)
 301 STRING)).  Returns nil if it is not visible in the current calendar window."
 302   (let ((m displayed-month)
 303         (y displayed-year))
 304     (increment-calendar-month m y (- 11 month))
 305     (if (> m 9)
 306       (list (list (list month day y) string)))))
 307
 308 (defun holiday-float (month dayname n string &optional day)
 309   "Holiday on MONTH, DAYNAME (Nth occurrence, Gregorian) called STRING.
 310 If the Nth DAYNAME in MONTH is visible, the value returned is the list
 311 \(((MONTH DAY year) STRING)).
 312
 313 If N<0, count backward from the end of MONTH.
 314
 315 An optional parameter DAY means the Nth DAYNAME after/before MONTH DAY.
 316
 317 Returns nil if it is not visible in the current calendar window."
 318   (let ((m displayed-month)
 319         (y displayed-year))
 320     (increment-calendar-month m y (- 11 month))
 321     (if (> m 9)
 322       (list (list (calendar-nth-named-day n dayname month y day) string)))))
 323
 324 (defun holiday-sexp (sexp string)
 325   "Sexp holiday for dates in the calendar window.
 326 SEXP is an expression in variable `year' evaluates to `date'.
 327
 328 STRING is an expression in `date' that evaluates to the holiday description
 329 of `date'.
 330
 331 If `date' is visible in the calendar window, the holiday STRING is on that
 332 date.  If date is nil, or if the date is not visible, there is no holiday."
 333   (let ((m displayed-month)
 334         (y displayed-year))
 335     (increment-calendar-month m y -1)
 336     (filter-visible-calendar-holidays
 337      (append
 338       (let* ((year y)
 339              (date (eval sexp))
 340              (string (if date (eval string))))
 341         (list (list date string)))
 342       (let* ((year (1+ y))
 343              (date (eval sexp))
 344              (string (if date (eval string))))
 345         (list (list date string)))))))
 346
 347 (defun holiday-advent ()
 348   "Date of Advent, if visible in calendar window."
 349   (let ((year displayed-year)
 350         (month displayed-month))
 351     (increment-calendar-month month year -1)
 352     (let ((advent (calendar-gregorian-from-absolute
 353                    (calendar-dayname-on-or-before 0
 354                     (calendar-absolute-from-gregorian
 355                      (list 12 3 year))))))
 356       (if (calendar-date-is-visible-p advent)
 357           (list (list advent "Advent"))))))
 358
 359 (defun holiday-easter-etc ()
 360   "List of dates related to Easter, as visible in calendar window."
 361  (if (and (> displayed-month 5) (not all-christian-calendar-holidays))
 362      nil;; Ash Wednesday, Good Friday, and Easter are not visible.
 363    (let* ((century (1+ (/ displayed-year 100)))
 364           (shifted-epact        ;; Age of moon for April 5...
 365            (% (+ 14 (* 11 (% displayed-year 19));;     ...by Nicaean rule
 366                  (-           ;; ...corrected for the Gregorian century rule
 367                   (/ (* 3 century) 4))
 368                  (/    ;; ...corrected for Metonic cycle inaccuracy.
 369                   (+ 5 (* 8 century)) 25)
 370                  (* 30 century));;              Keeps value positive.
 371               30))
 372           (adjusted-epact       ;;  Adjust for 29.5 day month.
 373            (if (or (= shifted-epact 0)
 374                    (and (= shifted-epact 1) (< 10 (% displayed-year 19))))
 375                (1+ shifted-epact)
 376              shifted-epact))
 377           (paschal-moon       ;; Day after the full moon on or after March 21.
 378            (- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
 379               adjusted-epact))
 380           (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))
 381           (mandatory
 382            (list
 383             (list (calendar-gregorian-from-absolute abs-easter)
 384                   "Easter Sunday")
 385             (list (calendar-gregorian-from-absolute (- abs-easter 2))
 386                   "Good Friday")
 387             (list (calendar-gregorian-from-absolute (- abs-easter 46))
 388                   "Ash Wednesday")))
 389           (optional
 390            (list
 391             (list (calendar-gregorian-from-absolute (- abs-easter 63))
 392                   "Septuagesima Sunday")
 393             (list (calendar-gregorian-from-absolute (- abs-easter 56))
 394                   "Sexagesima Sunday")
 395             (list (calendar-gregorian-from-absolute (- abs-easter 49))
 396                   "Shrove Sunday")
 397             (list (calendar-gregorian-from-absolute (- abs-easter 48))
 398                   "Shrove Monday")
 399             (list (calendar-gregorian-from-absolute (- abs-easter 47))
 400                   "Shrove Tuesday")
 401             (list (calendar-gregorian-from-absolute (- abs-easter 14))
 402                   "Passion Sunday")
 403             (list (calendar-gregorian-from-absolute (- abs-easter 7))
 404                   "Palm Sunday")
 405             (list (calendar-gregorian-from-absolute (- abs-easter 3))
 406                   "Maundy Thursday")
 407             (list (calendar-gregorian-from-absolute (+ abs-easter 35))
 408                   "Rogation Sunday")
 409             (list (calendar-gregorian-from-absolute (+ abs-easter 39))
 410                   "Ascension Day")
 411             (list (calendar-gregorian-from-absolute (+ abs-easter 49))
 412                   "Pentecost (Whitsunday)")
 413             (list (calendar-gregorian-from-absolute (+ abs-easter 50))
 414                   "Whitmonday")
 415             (list (calendar-gregorian-from-absolute (+ abs-easter 56))
 416                   "Trinity Sunday")
 417             (list (calendar-gregorian-from-absolute (+ abs-easter 60))
 418                   "Corpus Christi")))
 419           (output-list
 420            (filter-visible-calendar-holidays mandatory)))
 421      (if all-christian-calendar-holidays
 422          (setq output-list
 423                (append
 424                 (filter-visible-calendar-holidays optional)
 425                 output-list)))
 426      output-list)))
 427
 428 (defun holiday-greek-orthodox-easter ()
 429   "Date of Easter according to the rule of the Council of Nicaea."
 430   (let ((m displayed-month)
 431         (y displayed-year))
 432     (increment-calendar-month m y 1)
 433     (let* ((julian-year
 434             (extract-calendar-year
 435              (calendar-julian-from-absolute
 436               (calendar-absolute-from-gregorian
 437                (list m (calendar-last-day-of-month m y) y)))))
 438            (shifted-epact ;; Age of moon for April 5.
 439             (% (+ 14
 440                   (* 11 (% julian-year 19)))
 441                30))
 442            (paschal-moon  ;; Day after full moon on or after March 21.
 443             (- (calendar-absolute-from-julian (list 4 19 julian-year))
 444                shifted-epact))
 445            (nicaean-easter;; Sunday following the Paschal moon
 446             (calendar-gregorian-from-absolute
 447              (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))))
 448       (if (calendar-date-is-visible-p nicaean-easter)
 449           (list (list nicaean-easter "Pascha (Greek Orthodox Easter)"))))))
 450
 451 (defun filter-visible-calendar-holidays (l)
 452   "Return a list of all visible holidays of those on L."
 453   (let ((visible)
 454         (p l))
 455     (while p
 456       (and (car (car p))
 457            (calendar-date-is-visible-p (car (car p)))
 458            (setq visible (append (list (car p)) visible)))
 459       (setq p (cdr p)))
 460     visible))
 461
 462 (provide 'holidays)
 463
 464 ;;; holidays.el ends here