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

   1 ;;; calendar.el --- Calendar functions.
   2
   3 ;; Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1997
   4 ;;        Free Software Foundation, Inc.
   5
   6 ;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
   7 ;; Keywords: calendar
   8 ;; Human-Keywords: calendar, Gregorian calendar, diary, holidays
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; This collection of functions implements a calendar window.  It generates a
  30 ;; calendar for the current month, together with the previous and coming
  31 ;; months, or for any other three-month period.  The calendar can be scrolled
  32 ;; forward and backward in the window to show months in the past or future;
  33 ;; the cursor can move forward and backward by days, weeks, or months, making
  34 ;; it possible, for instance, to jump to the date a specified number of days,
  35 ;; weeks, or months from the date under the cursor.  The user can display a
  36 ;; list of holidays and other notable days for the period shown; the notable
  37 ;; days can be marked on the calendar, if desired.  The user can also specify
  38 ;; that dates having corresponding diary entries (in a file that the user
  39 ;; specifies) be marked; the diary entries for any date can be viewed in a
  40 ;; separate window.  The diary and the notable days can be viewed
  41 ;; independently of the calendar.  Dates can be translated from the (usual)
  42 ;; Gregorian calendar to the day of the year/days remaining in year, to the
  43 ;; ISO commercial calendar, to the Julian (old style) calendar, to the Hebrew
  44 ;; calendar, to the Islamic calendar, to the French Revolutionary calendar, to
  45 ;; the Mayan calendar, to the Chinese calendar, to the Coptic calendar, to the
  46 ;; Ethiopic calendar, and to the astronomical (Julian) day number.  When
  47 ;; floating point is available, times of sunrise/sunset can be displayed, as
  48 ;; can the phases of the moon.  Appointment notification for diary entries is
  49 ;; available.  Calendar printing via LaTeX is available.
  50
  51 ;; The following files are part of the calendar/diary code:
  52
  53 ;;       appt.el                       Appointment notification
  54 ;;       cal-china.el                  Chinese calendar
  55 ;;       cal-coptic.el                 Coptic/Ethiopic calendars
  56 ;;       cal-dst.el                    Daylight savings time rules
  57 ;;       cal-hebrew.el                 Hebrew calendar
  58 ;;       cal-islam.el                  Islamic calendar
  59 ;;       cal-iso.el                    ISO calendar
  60 ;;       cal-julian.el                 Julian/astronomical calendars
  61 ;;       cal-mayan.el                  Mayan calendars
  62 ;;       cal-menu.el                   Menu support
  63 ;;       cal-move.el                   Movement in the calendar
  64 ;;       cal-persia.el                 Persian calendar
  65 ;;       cal-tex.el                    Calendars in LaTeX
  66 ;;       cal-x.el                      X-windows dedicated frame functions
  67 ;;       diary-lib.el                  Diary functions
  68 ;;       holidays.el                   Holiday functions
  69 ;;       lunar.el                      Phases of the moon
  70 ;;       solar.el                      Sunrise/sunset, equinoxes/solstices
  71
  72 ;; Comments, corrections, and improvements should be sent to
  73 ;;  Edward M. Reingold               Department of Computer Science
  74 ;;  (217) 333-6733                   University of Illinois at Urbana-Champaign
  75 ;;  reingold@cs.uiuc.edu             1304 West Springfield Avenue
  76 ;;                                   Urbana, Illinois 61801
  77
  78 ;; Technical details of all the calendrical calculations can be found in
  79
  80 ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold,
  81 ;; Software--Practice and Experience, Volume 20, Number 9 (September, 1990),
  82 ;; pages 899-928.  ``Calendrical Calculations, Part II: Three Historical
  83 ;; Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
  84 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
  85 ;; pages 383-404.
  86
  87 ;; Hard copies of these two papers can be obtained by sending email to
  88 ;; reingold@cs.uiuc.edu with the SUBJECT "send-paper-cal" (no quotes) and
  89 ;; the message BODY containing your mailing address (snail).
  90
  91 ;;; Code:
  92
  93 (defun calendar-version ()
  94   (interactive)
  95   (message "Version 6, October 12, 1995"))
  96
  97 (defgroup calendar nil
  98   "Calendar and time management support."
  99   :group 'applications)
 100
 101 (defgroup diary nil
 102   "Emacs diary."
 103   :group 'calendar)
 104
 105 (defgroup appt nil
 106   "Appointment notification."
 107   :group 'calendar)
 108
 109 (defgroup holidays nil
 110   "Holidays support in calendar."
 111   :group 'calendar
 112   :prefix "calendar-"
 113   :group 'local)
 114
 115 (defgroup chinese-calendar nil
 116   "Chinese calendar support."
 117   :group 'calendar)
 118
 119 (defgroup calendar-tex nil
 120   "Options for printing calendar with LaTeX."
 121   :prefix "cal-tex-"
 122   :group 'calendar)
 123
 124 (defgroup calendar-hooks nil
 125   "Calendar hooks."
 126   :prefix "calendar-"
 127   :group 'calendar)
 128
 129
 130 ;;;###autoload
 131 (defcustom calendar-week-start-day 0
 132   "*The day of the week on which a week in the calendar begins.
 133 0 means Sunday (default), 1 means Monday, and so on."
 134   :type 'integer
 135   :group 'calendar)
 136
 137 ;;;###autoload
 138 (defcustom calendar-offset 0
 139   "*The offset of the principal month from the center of the calendar window.
 140 0 means the principal month is in the center (default), -1 means on the left,
 141 +1 means on the right.  Larger (or smaller) values push the principal month off
 142 the screen."
 143   :type 'integer
 144   :group 'calendar)
 145
 146 ;;;###autoload
 147 (defcustom view-diary-entries-initially nil
 148   "*Non-nil means display current date's diary entries on entry.
 149 The diary is displayed in another window when the calendar is first displayed,
 150 if the current date is visible.  The number of days of diary entries displayed
 151 is governed by the variable `number-of-diary-entries'."
 152   :type 'boolean
 153   :group 'diary)
 154
 155 ;;;###autoload
 156 (defcustom number-of-diary-entries 1
 157   "*Specifies how many days of diary entries are to be displayed initially.
 158 This variable affects the diary display when the command M-x diary is used,
 159 or if the value of the variable `view-diary-entries-initially' is t.  For
 160 example, if the default value 1 is used, then only the current day's diary
 161 entries will be displayed.  If the value 2 is used, then both the current
 162 day's and the next day's entries will be displayed.
 163
 164 The value can also be a vector such as [0 2 2 2 2 4 1]; this value
 165 says to display no diary entries on Sunday, the display the entries
 166 for the current date and the day after on Monday through Thursday,
 167 display Friday through Monday's entries on Friday, and display only
 168 Saturday's entries on Saturday.
 169
 170 This variable does not affect the diary display with the `d' command
 171 from the calendar; in that case, the prefix argument controls the
 172 number of days of diary entries displayed."
 173   :type '(choice (integer :tag "Entries")
 174                  (vector :value [0 0 0 0 0 0 0]
 175                          (integer :tag "Sunday")
 176                          (integer :tag "Monday")
 177                          (integer :tag "Tuesday")
 178                          (integer :tag "Wednesday")
 179                          (integer :tag "Thursday")
 180                          (integer :tag "Friday")
 181                          (integer :tag "Saturday")))
 182   :group 'diary)
 183
 184 ;;;###autoload
 185 (defcustom mark-diary-entries-in-calendar nil
 186   "*Non-nil means mark dates with diary entries, in the calendar window.
 187 The marking symbol is specified by the variable `diary-entry-marker'."
 188   :type 'boolean
 189   :group 'diary)
 190
 191 (defcustom diary-entry-marker
 192   (if (not window-system)
 193       "+"
 194     (require 'faces)
 195     (add-to-list 'facemenu-unlisted-faces 'diary-face)
 196     (make-face 'diary-face)
 197     (cond ((face-differs-from-default-p 'diary-face))
 198           ((x-display-color-p) (set-face-foreground 'diary-face "red"))
 199           (t (copy-face 'bold 'diary-face)))
 200     'diary-face)
 201   "*Used to mark dates that have diary entries.
 202 Can be either a single-character string or a face."
 203   :type '(choice string face)
 204   :group 'diary)
 205
 206 (defcustom calendar-today-marker
 207   (if (not window-system)
 208       "="
 209     (require 'faces)
 210     (add-to-list 'facemenu-unlisted-faces 'calendar-today-face)
 211     (make-face 'calendar-today-face)
 212     (if (not (face-differs-from-default-p 'calendar-today-face))
 213         (set-face-underline-p 'calendar-today-face t))
 214     'calendar-today-face)
 215   "*Used to mark today's date.
 216 Can be either a single-character string or a face."
 217   :type '(choice string face)
 218   :group 'calendar)
 219
 220 (defcustom calendar-holiday-marker
 221   (if (not window-system)
 222       "*"
 223     (require 'faces)
 224     (add-to-list 'facemenu-unlisted-faces 'holiday-face)
 225     (make-face 'holiday-face)
 226     (cond ((face-differs-from-default-p 'holiday-face))
 227           ((x-display-color-p) (set-face-background 'holiday-face "pink"))
 228           (t (set-face-background 'holiday-face "black")
 229              (set-face-foreground 'holiday-face "white")))
 230     'holiday-face)
 231   "*Used to mark notable dates in the calendar.
 232 Can be either a single-character string or a face."
 233   :type '(choice string face)
 234   :group 'calendar)
 235
 236 ;;;###autoload
 237 (defcustom view-calendar-holidays-initially nil
 238   "*Non-nil means display holidays for current three month period on entry.
 239 The holidays are displayed in another window when the calendar is first
 240 displayed."
 241   :type 'boolean
 242   :group 'holidays)
 243
 244 ;;;###autoload
 245 (defcustom mark-holidays-in-calendar nil
 246   "*Non-nil means mark dates of holidays in the calendar window.
 247 The marking symbol is specified by the variable `calendar-holiday-marker'."
 248   :type 'boolean
 249   :group 'holidays)
 250
 251 ;;;###autoload
 252 (defcustom all-hebrew-calendar-holidays nil
 253   "*If nil, show only major holidays from the Hebrew calendar.
 254 This means only those Jewish holidays that appear on secular calendars.
 255
 256 If t, show all the holidays that would appear in a complete Hebrew calendar."
 257   :type 'boolean
 258   :group 'holidays)
 259
 260 ;;;###autoload
 261 (defcustom all-christian-calendar-holidays nil
 262   "*If nil, show only major holidays from the Christian calendar.
 263 This means only those Christian holidays that appear on secular calendars.
 264
 265 If t, show all the holidays that would appear in a complete Christian
 266 calendar."
 267   :type 'boolean
 268   :group 'holidays)
 269
 270 ;;;###autoload
 271 (defcustom all-islamic-calendar-holidays nil
 272   "*If nil, show only major holidays from the Islamic calendar.
 273 This means only those Islamic holidays that appear on secular calendars.
 274
 275 If t, show all the holidays that would appear in a complete Islamic
 276 calendar."
 277   :type 'boolean
 278   :group 'holidays)
 279
 280 ;;;###autoload
 281 (defcustom calendar-load-hook nil
 282   "*List of functions to be called after the calendar is first loaded.
 283 This is the place to add key bindings to `calendar-mode-map'."
 284   :type 'hook
 285   :group 'calendar-hooks)
 286
 287 ;;;###autoload
 288 (defcustom initial-calendar-window-hook nil
 289   "*List of functions to be called when the calendar window is first opened.
 290 The functions invoked are called after the calendar window is opened, but
 291 once opened is never called again.  Leaving the calendar with the `q' command
 292 and reentering it will cause these functions to be called again."
 293   :type 'hook
 294   :group 'calendar-hooks)
 295
 296 ;;;###autoload
 297 (defcustom today-visible-calendar-hook nil
 298   "*List of functions called whenever the current date is visible.
 299 This can be used, for example, to replace today's date with asterisks; a
 300 function `calendar-star-date' is included for this purpose:
 301     (setq today-visible-calendar-hook 'calendar-star-date)
 302 It can also be used to mark the current date with `calendar-today-marker';
 303 a function is also provided for this:
 304     (setq today-visible-calendar-hook 'calendar-mark-today)
 305
 306 The corresponding variable `today-invisible-calendar-hook' is the list of
 307 functions called when the calendar function was called when the current
 308 date is not visible in the window.
 309
 310 Other than the use of the provided functions, the changing of any
 311 characters in the calendar buffer by the hooks may cause the failure of the
 312 functions that move by days and weeks."
 313   :type 'hook
 314   :group 'calendar-hooks)
 315
 316 ;;;###autoload
 317 (defcustom today-invisible-calendar-hook nil
 318   "*List of functions called whenever the current date is not visible.
 319
 320 The corresponding variable `today-visible-calendar-hook' is the list of
 321 functions called when the calendar function was called when the current
 322 date is visible in the window.
 323
 324 Other than the use of the provided functions, the changing of any
 325 characters in the calendar buffer by the hooks may cause the failure of the
 326 functions that move by days and weeks."
 327   :type 'hook
 328   :group 'calendar-hooks)
 329
 330 ;;;###autoload
 331 (defcustom diary-file "~/diary"
 332   "*Name of the file in which one's personal diary of dates is kept.
 333
 334 The file's entries are lines in any of the forms
 335
 336             MONTH/DAY
 337             MONTH/DAY/YEAR
 338             MONTHNAME DAY
 339             MONTHNAME DAY, YEAR
 340             DAYNAME
 341
 342 at the beginning of the line; the remainder of the line is the diary entry
 343 string for that date.  MONTH and DAY are one or two digit numbers, YEAR is
 344 a number and may be written in full or abbreviated to the final two digits.
 345 If the date does not contain a year, it is generic and applies to any year.
 346 DAYNAME entries apply to any date on which is on that day of the week.
 347 MONTHNAME and DAYNAME can be spelled in full, abbreviated to three
 348 characters (with or without a period), capitalized or not.  Any of DAY,
 349 MONTH, or MONTHNAME, YEAR can be `*' which matches any day, month, or year,
 350 respectively.
 351
 352 The European style (in which the day precedes the month) can be used
 353 instead, if you execute `european-calendar' when in the calendar, or set
 354 `european-calendar-style' to t in your .emacs file.  The European forms are
 355
 356             DAY/MONTH
 357             DAY/MONTH/YEAR
 358             DAY MONTHNAME
 359             DAY MONTHNAME YEAR
 360             DAYNAME
 361
 362 To revert to the default American style from the European style, execute
 363 `american-calendar' in the calendar.
 364
 365 A diary entry can be preceded by the character
 366 `diary-nonmarking-symbol' (ordinarily `&') to make that entry
 367 nonmarking--that is, it will not be marked on dates in the calendar
 368 window but will appear in a diary window.
 369
 370 Multiline diary entries are made by indenting lines after the first with
 371 either a TAB or one or more spaces.
 372
 373 Lines not in one the above formats are ignored.  Here are some sample diary
 374 entries (in the default American style):
 375
 376      12/22/1988 Twentieth wedding anniversary!!
 377      &1/1. Happy New Year!
 378      10/22 Ruth's birthday.
 379      21: Payday
 380      Tuesday--weekly meeting with grad students at 10am
 381               Supowit, Shen, Bitner, and Kapoor to attend.
 382      1/13/89 Friday the thirteenth!!
 383      &thu 4pm squash game with Lloyd.
 384      mar 16 Dad's birthday
 385      April 15, 1989 Income tax due.
 386      &* 15 time cards due.
 387
 388 If the first line of a diary entry consists only of the date or day name with
 389 no trailing blanks or punctuation, then that line is not displayed in the
 390 diary window; only the continuation lines is shown.  For example, the
 391 single diary entry
 392
 393      02/11/1989
 394       Bill Blattner visits Princeton today
 395       2pm Cognitive Studies Committee meeting
 396       2:30-5:30 Lizzie at Lawrenceville for `Group Initiative'
 397       4:00pm Jamie Tappenden
 398       7:30pm Dinner at George and Ed's for Alan Ryan
 399       7:30-10:00pm dance at Stewart Country Day School
 400
 401 will appear in the diary window without the date line at the beginning.  This
 402 facility allows the diary window to look neater, but can cause confusion if
 403 used with more than one day's entries displayed.
 404
 405 Diary entries can be based on Lisp sexps.  For example, the diary entry
 406
 407       %%(diary-block 11 1 1990 11 10 1990) Vacation
 408
 409 causes the diary entry \"Vacation\" to appear from November 1 through November
 410 10, 1990.  Other functions available are `diary-float', `diary-anniversary',
 411 `diary-cyclic', `diary-day-of-year', `diary-iso-date', `diary-french-date',
 412 `diary-hebrew-date', `diary-islamic-date', `diary-mayan-date',
 413 `diary-chinese-date', `diary-coptic-date', `diary-ethiopic-date',
 414 `diary-persian-date', `diary-yahrzeit', `diary-sunrise-sunset',
 415 `diary-phases-of-moon', `diary-parasha', `diary-omer', `diary-rosh-hodesh',
 416 and `diary-sabbath-candles'.  See the documentation for the function
 417 `list-sexp-diary-entries' for more details.
 418
 419 Diary entries based on the Hebrew and/or the Islamic calendar are also
 420 possible, but because these are somewhat slow, they are ignored
 421 unless you set the `nongregorian-diary-listing-hook' and the
 422 `nongregorian-diary-marking-hook' appropriately.  See the documentation
 423 for these functions for details.
 424
 425 Diary files can contain directives to include the contents of other files; for
 426 details, see the documentation for the variable `list-diary-entries-hook'."
 427   :type 'file
 428   :group 'diary)
 429
 430 ;;;###autoload
 431 (defcustom diary-nonmarking-symbol "&"
 432   "*Symbol indicating that a diary entry is not to be marked in the calendar."
 433   :type 'string
 434   :group 'diary)
 435
 436 ;;;###autoload
 437 (defcustom hebrew-diary-entry-symbol "H"
 438   "*Symbol indicating a diary entry according to the Hebrew calendar."
 439   :type 'string
 440   :group 'diary)
 441
 442 ;;;###autoload
 443 (defcustom islamic-diary-entry-symbol "I"
 444   "*Symbol indicating a diary entry according to the Islamic calendar."
 445   :type 'string
 446   :group 'diary)
 447
 448 ;;;###autoload
 449 (defcustom diary-include-string "#include"
 450   "*The string indicating inclusion of another file of diary entries.
 451 See the documentation for the function `include-other-diary-files'."
 452   :type 'string
 453   :group 'diary)
 454
 455 ;;;###autoload
 456 (defcustom sexp-diary-entry-symbol "%%"
 457   "*The string used to indicate a sexp diary entry in diary-file.
 458 See the documentation for the function `list-sexp-diary-entries'."
 459   :type 'string
 460   :group 'diary)
 461
 462 ;;;###autoload
 463 (defcustom abbreviated-calendar-year t
 464   "*Interpret a two-digit year DD in a diary entry as either 19DD or 20DD.
 465 For the Gregorian calendar; similarly for the Hebrew and Islamic calendars.
 466 If this variable is nil, years must be written in full."
 467   :type 'boolean
 468   :group 'diary)
 469
 470 ;;;###autoload
 471 (defcustom european-calendar-style nil
 472   "*Use the European style of dates in the diary and in any displays.
 473 If this variable is t, a date 1/2/1990 would be interpreted as February 1,
 474 1990.  The accepted European date styles are
 475
 476             DAY/MONTH
 477             DAY/MONTH/YEAR
 478             DAY MONTHNAME
 479             DAY MONTHNAME YEAR
 480             DAYNAME
 481
 482 Names can be capitalized or not, written in full, or abbreviated to three
 483 characters with or without a period."
 484   :type 'boolean
 485   :group 'diary)
 486
 487 ;;;###autoload
 488 (defcustom american-date-diary-pattern
 489   '((month "/" day "[^/0-9]")
 490     (month "/" day "/" year "[^0-9]")
 491     (monthname " *" day "[^,0-9]")
 492     (monthname " *" day ", *" year "[^0-9]")
 493     (dayname "\\W"))
 494   "*List of pseudo-patterns describing the American patterns of date used.
 495 See the documentation of `diary-date-forms' for an explanation."
 496   :type '(repeat (choice (cons :tag "Backup"
 497                                :value (backup . nil)
 498                                (const backup)
 499                                (repeat (list :inline t :format "%v"
 500                                              (symbol :tag "Keyword")
 501                                              (choice symbol regexp))))
 502                          (repeat (list :inline t :format "%v"
 503                                        (symbol :tag "Keyword")
 504                                        (choice symbol regexp)))))
 505   :group 'diary)
 506
 507 ;;;###autoload
 508 (defcustom european-date-diary-pattern
 509   '((day "/" month "[^/0-9]")
 510     (day "/" month "/" year "[^0-9]")
 511     (backup day " *" monthname "\\W+\\<[^*0-9]")
 512     (day " *" monthname " *" year "[^0-9]")
 513     (dayname "\\W"))
 514   "*List of pseudo-patterns describing the European patterns of date used.
 515 See the documentation of `diary-date-forms' for an explanation."
 516   :type '(repeat (choice (cons :tag "Backup"
 517                                :value (backup . nil)
 518                                (const backup)
 519                                (repeat (list :inline t :format "%v"
 520                                              (symbol :tag "Keyword")
 521                                              (choice symbol regexp))))
 522                          (repeat (list :inline t :format "%v"
 523                                        (symbol :tag "Keyword")
 524                                        (choice symbol regexp)))))
 525   :group 'diary)
 526
 527 (defcustom diary-date-forms
 528   (if european-calendar-style
 529       european-date-diary-pattern
 530     american-date-diary-pattern)
 531   "*List of pseudo-patterns describing the forms of date used in the diary.
 532 The patterns on the list must be MUTUALLY EXCLUSIVE and must should not match
 533 any portion of the diary entry itself, just the date component.
 534
 535 A pseudo-pattern is a list of regular expressions and the keywords `month',
 536 `day', `year', `monthname', and `dayname'.  The keyword `monthname' will
 537 match the name of the month, capitalized or not, or its three-letter
 538 abbreviation, followed by a period or not; it will also match `*'.
 539 Similarly, `dayname' will match the name of the day, capitalized or not, or
 540 its three-letter abbreviation, followed by a period or not.  The keywords
 541 `month', `day', and `year' will match those numerical values, preceded by
 542 arbitrarily many zeros; they will also match `*'.
 543
 544 The matching of the diary entries with the date forms is done with the
 545 standard syntax table from Fundamental mode, but with the `*' changed so
 546 that it is a word constituent.
 547
 548 If, to be mutually exclusive, a pseudo-pattern must match a portion of the
 549 diary entry itself, the first element of the pattern MUST be `backup'.  This
 550 directive causes the date recognizer to back up to the beginning of the
 551 current word of the diary entry, so in no case can the pattern match more than
 552 a portion of the first word of the diary entry."
 553   :type '(repeat (choice (cons :tag "Backup"
 554                                :value (backup . nil)
 555                                (const backup)
 556                                (repeat (list :inline t :format "%v"
 557                                              (symbol :tag "Keyword")
 558                                              (choice symbol regexp))))
 559                          (repeat (list :inline t :format "%v"
 560                                        (symbol :tag "Keyword")
 561                                        (choice symbol regexp)))))
 562   :group 'diary)
 563
 564 ;;;###autoload
 565 (defcustom european-calendar-display-form
 566   '((if dayname (concat dayname ", ")) day " " monthname " " year)
 567   "*Pseudo-pattern governing the way a date appears in the European style.
 568 See the documentation of calendar-date-display-form for an explanation."
 569   :type 'sexp
 570   :group 'calendar)
 571
 572 ;;;###autoload
 573 (defcustom american-calendar-display-form
 574   '((if dayname (concat dayname ", ")) monthname " " day ", " year)
 575   "*Pseudo-pattern governing the way a date appears in the American style.
 576 See the documentation of `calendar-date-display-form' for an explanation."
 577   :type 'sexp
 578   :group 'calendar)
 579
 580 (defcustom calendar-date-display-form
 581   (if european-calendar-style
 582       european-calendar-display-form
 583     american-calendar-display-form)
 584   "*Pseudo-pattern governing the way a date appears.
 585
 586 Used by the function `calendar-date-string', a pseudo-pattern is a list of
 587 expressions that can involve the keywords `month', `day', and `year', all
 588 numbers in string form, and `monthname' and `dayname', both alphabetic
 589 strings.  For example, the ISO standard would use the pseudo- pattern
 590
 591        '(year \"-\" month \"-\" day)
 592
 593 while a typical American form would be
 594
 595        '(month \"/\" day \"/\" (substring year -2))
 596
 597 and
 598
 599        '((format \"%9s, %9s %2s, %4s\" dayname monthname day year))
 600
 601 would give the usual American style in fixed-length fields.
 602
 603 See the documentation of the function `calendar-date-string'."
 604   :type 'sexp
 605   :group 'calendar)
 606
 607 (defun european-calendar ()
 608   "Set the interpretation and display of dates to the European style."
 609   (interactive)
 610   (setq european-calendar-style t)
 611   (setq calendar-date-display-form european-calendar-display-form)
 612   (setq diary-date-forms european-date-diary-pattern)
 613   (update-calendar-mode-line))
 614
 615 (defun american-calendar ()
 616   "Set the interpretation and display of dates to the American style."
 617   (interactive)
 618   (setq european-calendar-style nil)
 619   (setq calendar-date-display-form american-calendar-display-form)
 620   (setq diary-date-forms american-date-diary-pattern)
 621   (update-calendar-mode-line))
 622
 623 ;;;###autoload
 624 (defcustom print-diary-entries-hook 'lpr-buffer
 625   "*List of functions called after a temporary diary buffer is prepared.
 626 The buffer shows only the diary entries currently visible in the diary
 627 buffer.  The default just does the printing.  Other uses might include, for
 628 example, rearranging the lines into order by day and time, saving the buffer
 629 instead of deleting it, or changing the function used to do the printing."
 630   :type 'hook
 631   :group 'diary)
 632
 633 ;;;###autoload
 634 (defcustom list-diary-entries-hook nil
 635   "*List of functions called after diary file is culled for relevant entries.
 636 It is to be used for diary entries that are not found in the diary file.
 637
 638 A function `include-other-diary-files' is provided for use as the value of
 639 this hook.  This function enables you to use shared diary files together
 640 with your own.  The files included are specified in the diary file by lines
 641 of the form
 642
 643         #include \"filename\"
 644
 645 This is recursive; that is, #include directives in files thus included are
 646 obeyed.  You can change the \"#include\" to some other string by changing
 647 the variable `diary-include-string'.  When you use `include-other-diary-files'
 648 as part of the list-diary-entries-hook, you will probably also want to use the
 649 function `mark-included-diary-files' as part of `mark-diary-entries-hook'.
 650
 651 For example, you could use
 652
 653      (setq list-diary-entries-hook
 654        '(include-other-diary-files sort-diary-entries))
 655      (setq diary-display-hook 'fancy-diary-display)
 656
 657 in your `.emacs' file to cause the fancy diary buffer to be displayed with
 658 diary entries from various included files, each day's entries sorted into
 659 lexicographic order."
 660   :type 'hook
 661   :group 'diary)
 662
 663 ;;;###autoload
 664 (defcustom diary-hook nil
 665   "*List of functions called after the display of the diary.
 666 Can be used for appointment notification."
 667   :type 'hook
 668   :group 'diary)
 669
 670 ;;;###autoload
 671 (defcustom diary-display-hook nil
 672   "*List of functions that handle the display of the diary.
 673 If nil (the default), `simple-diary-display' is used.  Use `ignore' for no
 674 diary display.
 675
 676 Ordinarily, this just displays the diary buffer (with holidays indicated in
 677 the mode line), if there are any relevant entries.  At the time these
 678 functions are called, the variable `diary-entries-list' is a list, in order
 679 by date, of all relevant diary entries in the form of ((MONTH DAY YEAR)
 680 STRING), where string is the diary entry for the given date.  This can be
 681 used, for example, a different buffer for display (perhaps combined with
 682 holidays), or produce hard copy output.
 683
 684 A function `fancy-diary-display' is provided as an alternative
 685 choice for this hook; this function prepares a special noneditable diary
 686 buffer with the relevant diary entries that has neat day-by-day arrangement
 687 with headings.  The fancy diary buffer will show the holidays unless the
 688 variable `holidays-in-diary-buffer' is set to nil.  Ordinarily, the fancy
 689 diary buffer will not show days for which there are no diary entries, even
 690 if that day is a holiday; if you want such days to be shown in the fancy
 691 diary buffer, set the variable `diary-list-include-blanks' to t."
 692   :type 'hook
 693   :group 'diary)
 694
 695 ;;;###autoload
 696 (defcustom nongregorian-diary-listing-hook nil
 697   "*List of functions called for listing diary file and included files.
 698 As the files are processed for diary entries, these functions are used to cull
 699 relevant entries.  You can use either or both of `list-hebrew-diary-entries'
 700 and `list-islamic-diary-entries'.  The documentation for these functions
 701 describes the style of such diary entries."
 702   :type 'hook
 703   :group 'diary)
 704
 705 ;;;###autoload
 706 (defcustom mark-diary-entries-hook nil
 707   "*List of functions called after marking diary entries in the calendar.
 708
 709 A function `mark-included-diary-files' is also provided for use as the
 710 mark-diary-entries-hook; it enables you to use shared diary files together
 711 with your own.  The files included are specified in the diary file by lines
 712 of the form
 713         #include \"filename\"
 714 This is recursive; that is, #include directives in files thus included are
 715 obeyed.  You can change the \"#include\" to some other string by changing the
 716 variable `diary-include-string'.  When you use `mark-included-diary-files' as
 717 part of the mark-diary-entries-hook, you will probably also want to use the
 718 function `include-other-diary-files' as part of `list-diary-entries-hook'."
 719   :type 'hook
 720   :group 'diary)
 721
 722 ;;;###autoload
 723 (defcustom nongregorian-diary-marking-hook nil
 724   "*List of functions called for marking diary file and included files.
 725 As the files are processed for diary entries, these functions are used to cull
 726 relevant entries.  You can use either or both of `mark-hebrew-diary-entries'
 727 and `mark-islamic-diary-entries'.  The documentation for these functions
 728 describes the style of such diary entries."
 729   :type 'hook
 730   :group 'diary)
 731
 732 ;;;###autoload
 733 (defcustom diary-list-include-blanks nil
 734   "*If nil, do not include days with no diary entry in the list of diary entries.
 735 Such days will then not be shown in the the fancy diary buffer, even if they
 736 are holidays."
 737   :type 'boolean
 738   :group 'diary)
 739
 740 ;;;###autoload
 741 (defcustom holidays-in-diary-buffer t
 742   "*Non-nil means include holidays in the diary display.
 743 The holidays appear in the mode line of the diary buffer, or in the
 744 fancy diary buffer next to the date.  This slows down the diary functions
 745 somewhat; setting it to nil makes the diary display faster."
 746   :type 'boolean
 747   :group 'holidays)
 748
 749 (defvar calendar-mark-ring nil)
 750
 751 ;;;###autoload
 752 (put 'general-holidays 'risky-local-variable t)
 753 ;;;###autoload
 754 (defcustom general-holidays
 755   '((holiday-fixed 1 1 "New Year's Day")
 756     (holiday-float 1 1 3 "Martin Luther King Day")
 757     (holiday-fixed 2 2 "Ground Hog Day")
 758     (holiday-fixed 2 14 "Valentine's Day")
 759     (holiday-float 2 1 3 "President's Day")
 760     (holiday-fixed 3 17 "St. Patrick's Day")
 761     (holiday-fixed 4 1 "April Fools' Day")
 762     (holiday-float 5 0 2 "Mother's Day")
 763     (holiday-float 5 1 -1 "Memorial Day")
 764     (holiday-fixed 6 14 "Flag Day")
 765     (holiday-float 6 0 3 "Father's Day")
 766     (holiday-fixed 7 4 "Independence Day")
 767     (holiday-float 9 1 1 "Labor Day")
 768     (holiday-float 10 1 2 "Columbus Day")
 769     (holiday-fixed 10 31 "Halloween")
 770     (holiday-fixed 11 11 "Veteran's Day")
 771     (holiday-float 11 4 4 "Thanksgiving"))
 772   "*General holidays.  Default value is for the United States.
 773 See the documentation for `calendar-holidays' for details."
 774   :type 'sexp
 775   :group 'holidays)
 776
 777 ;;;###autoload
 778 (put 'oriental-holidays 'risky-local-variable t)
 779 ;;;###autoload
 780 (defcustom oriental-holidays
 781   '((if (fboundp 'atan)
 782         (holiday-chinese-new-year)))
 783   "*Oriental holidays.
 784 See the documentation for `calendar-holidays' for details."
 785   :type 'sexp
 786   :group 'holidays)
 787
 788 ;;;###autoload
 789 (put 'local-holidays 'risky-local-variable t)
 790 ;;;###autoload
 791 (defcustom local-holidays nil
 792   "*Local holidays.
 793 See the documentation for `calendar-holidays' for details."
 794   :type 'sexp
 795   :group 'holidays)
 796
 797 ;;;###autoload
 798 (put 'other-holidays 'risky-local-variable t)
 799 ;;;###autoload
 800 (defcustom other-holidays nil
 801   "*User defined holidays.
 802 See the documentation for `calendar-holidays' for details."
 803   :type 'sexp
 804   :group 'holidays)
 805
 806 ;;;###autoload
 807 (put 'hebrew-holidays-1 'risky-local-variable t)
 808 ;;;###autoload
 809 (defvar hebrew-holidays-1
 810   '((holiday-rosh-hashanah-etc)
 811     (if all-hebrew-calendar-holidays
 812         (holiday-julian
 813          11
 814          (let* ((m displayed-month)
 815                 (y displayed-year)
 816                 (year))
 817            (increment-calendar-month m y -1)
 818            (let ((year (extract-calendar-year
 819                         (calendar-julian-from-absolute
 820                          (calendar-absolute-from-gregorian
 821                           (list m 1 y))))))
 822              (if (zerop (% (1+ year) 4))
 823                  22
 824                21))) "\"Tal Umatar\" (evening)"))))
 825
 826 ;;;###autoload
 827 (put 'hebrew-holidays-2 'risky-local-variable t)
 828 ;;;###autoload
 829 (defvar hebrew-holidays-2
 830   '((if all-hebrew-calendar-holidays
 831         (holiday-hanukkah)
 832       (holiday-hebrew 9 25 "Hanukkah"))
 833     (if all-hebrew-calendar-holidays
 834       (holiday-hebrew
 835        10
 836        (let ((h-year (extract-calendar-year
 837                       (calendar-hebrew-from-absolute
 838                        (calendar-absolute-from-gregorian
 839                         (list displayed-month 28 displayed-year))))))
 840          (if (= (% (calendar-absolute-from-hebrew (list 10 10 h-year))
 841                    7)
 842                 6)
 843              11 10))
 844        "Tzom Teveth"))
 845     (if all-hebrew-calendar-holidays
 846         (holiday-hebrew 11 15 "Tu B'Shevat"))))
 847
 848 ;;;###autoload
 849 (put 'hebrew-holidays-3 'risky-local-variable t)
 850 ;;;###autoload
 851 (defvar hebrew-holidays-3
 852   '((if all-hebrew-calendar-holidays
 853         (holiday-hebrew
 854          11
 855          (let ((m displayed-month)
 856                (y displayed-year))
 857            (increment-calendar-month m y 1)
 858            (let* ((h-year (extract-calendar-year
 859                            (calendar-hebrew-from-absolute
 860                             (calendar-absolute-from-gregorian
 861                              (list m
 862                                    (calendar-last-day-of-month m y)
 863                                    y)))))
 864                   (s-s
 865                    (calendar-hebrew-from-absolute
 866                     (if (=
 867                          (% (calendar-absolute-from-hebrew
 868                              (list 7 1 h-year))
 869                             7)
 870                          6)
 871                         (calendar-dayname-on-or-before
 872                          6 (calendar-absolute-from-hebrew
 873                             (list 11 17 h-year)))
 874                       (calendar-dayname-on-or-before
 875                        6 (calendar-absolute-from-hebrew
 876                           (list 11 16 h-year))))))
 877                   (day (extract-calendar-day s-s)))
 878              day))
 879          "Shabbat Shirah"))))
 880
 881 ;;;###autoload
 882 (put 'hebrew-holidays-4 'risky-local-variable t)
 883 ;;;###autoload
 884 (defvar hebrew-holidays-4
 885   '((holiday-passover-etc)
 886     (if (and all-hebrew-calendar-holidays
 887              (let* ((m displayed-month)
 888                     (y displayed-year)
 889                     (year))
 890                (increment-calendar-month m y -1)
 891                (let ((year (extract-calendar-year
 892                             (calendar-julian-from-absolute
 893                              (calendar-absolute-from-gregorian
 894                               (list m 1 y))))))
 895                  (= 21 (% year 28)))))
 896         (holiday-julian 3 26 "Kiddush HaHamah"))
 897     (if all-hebrew-calendar-holidays
 898         (holiday-tisha-b-av-etc))))
 899
 900 ;;;###autoload
 901 (put 'hebrew-holidays 'risky-local-variable t)
 902 ;;;###autoload
 903 (defcustom hebrew-holidays (append hebrew-holidays-1 hebrew-holidays-2
 904                                 hebrew-holidays-3 hebrew-holidays-4)
 905   "*Jewish holidays.
 906 See the documentation for `calendar-holidays' for details."
 907   :type 'sexp
 908   :group 'holidays)
 909
 910 ;;;###autoload
 911 (put 'christian-holidays 'risky-local-variable t)
 912 ;;;###autoload
 913 (defcustom christian-holidays
 914   '((if all-christian-calendar-holidays
 915         (holiday-fixed 1 6 "Epiphany"))
 916     (holiday-easter-etc)
 917     (if all-christian-calendar-holidays
 918         (holiday-greek-orthodox-easter))
 919     (if all-christian-calendar-holidays
 920         (holiday-fixed 8 15 "Assumption"))
 921     (if all-christian-calendar-holidays
 922         (holiday-advent))
 923     (holiday-fixed 12 25 "Christmas")
 924     (if all-christian-calendar-holidays
 925         (holiday-julian 12 25 "Eastern Orthodox Christmas")))
 926   "*Christian holidays.
 927 See the documentation for `calendar-holidays' for details."
 928   :type 'sexp
 929   :group 'holidays)
 930
 931 ;;;###autoload
 932 (put 'islamic-holidays 'risky-local-variable t)
 933 ;;;###autoload
 934 (defcustom islamic-holidays
 935   '((holiday-islamic
 936      1 1
 937      (format "Islamic New Year %d"
 938              (let ((m displayed-month)
 939                    (y displayed-year))
 940                (increment-calendar-month m y 1)
 941                (extract-calendar-year
 942                 (calendar-islamic-from-absolute
 943                  (calendar-absolute-from-gregorian
 944                   (list
 945                    m (calendar-last-day-of-month m y) y)))))))
 946     (if all-islamic-calendar-holidays
 947         (holiday-islamic 1 10 "Ashura"))
 948     (if all-islamic-calendar-holidays
 949         (holiday-islamic 3 12 "Mulad-al-Nabi"))
 950     (if all-islamic-calendar-holidays
 951         (holiday-islamic 7 26 "Shab-e-Mi'raj"))
 952     (if all-islamic-calendar-holidays
 953         (holiday-islamic 8 15 "Shab-e-Bara't"))
 954     (holiday-islamic 9 1 "Ramadan Begins")
 955     (if all-islamic-calendar-holidays
 956         (holiday-islamic 9 27 "Shab-e Qadr"))
 957     (if all-islamic-calendar-holidays
 958         (holiday-islamic 10 1 "Id-al-Fitr"))
 959     (if all-islamic-calendar-holidays
 960         (holiday-islamic 12 10 "Id-al-Adha")))
 961   "*Islamic holidays.
 962 See the documentation for `calendar-holidays' for details."
 963   :type 'sexp
 964   :group 'holidays)
 965
 966 ;;;###autoload
 967 (put 'solar-holidays 'risky-local-variable t)
 968 ;;;###autoload
 969 (defcustom solar-holidays
 970   '((if (fboundp 'atan)
 971         (solar-equinoxes-solstices))
 972     (if (progn
 973           (require 'cal-dst)
 974           t)
 975       (funcall
 976        'holiday-sexp
 977         calendar-daylight-savings-starts
 978         '(format "Daylight Savings Time Begins %s"
 979                   (if (fboundp 'atan)
 980                       (solar-time-string
 981                        (/ calendar-daylight-savings-starts-time (float 60))
 982                        calendar-standard-time-zone-name)
 983                     ""))))
 984     (funcall
 985      'holiday-sexp
 986      calendar-daylight-savings-ends
 987      '(format "Daylight Savings Time Ends %s"
 988               (if (fboundp 'atan)
 989                   (solar-time-string
 990                    (/ calendar-daylight-savings-ends-time (float 60))
 991                    calendar-daylight-time-zone-name)
 992                 ""))))
 993   "*Sun-related holidays.
 994 See the documentation for `calendar-holidays' for details."
 995   :type 'sexp
 996   :group 'holidays)
 997
 998 ;;;###autoload
 999 (put 'calendar-holidays 'risky-local-variable t)
1000 (defcustom calendar-holidays
1001   (append general-holidays local-holidays other-holidays
1002           christian-holidays hebrew-holidays islamic-holidays
1003           oriental-holidays solar-holidays)
1004   "*List of notable days for the command M-x holidays.
1005
1006 Additional holidays are easy to add to the list, just put them in the list
1007 `other-holidays' in your .emacs file.  Similarly, by setting any of
1008 `general-holidays', `local-holidays' `christian-holidays', `hebrew-holidays',
1009 `islamic-holidays', `oriental-holidays', or `solar-holidays' to nil in your
1010 .emacs file, you can eliminate unwanted categories of holidays.  The intention
1011 is that (in the US) `local-holidays' be set in site-init.el and
1012 `other-holidays' be set by the user.
1013
1014 Entries on the list are expressions that return (possibly empty) lists of
1015 items of the form ((month day year) string) of a holiday in the in the
1016 three-month period centered around `displayed-month' of `displayed-year'.
1017 Several basic functions are provided for this purpose:
1018
1019     (holiday-fixed MONTH DAY STRING) is a fixed date on the Gregorian calendar
1020     (holiday-float MONTH DAYNAME K STRING &optional day) is the Kth DAYNAME in
1021                                MONTH on the Gregorian calendar (0 for Sunday,
1022                                etc.); K<0 means count back from the end of the
1023                                month. An optional parameter DAY means the Kth
1024                                DAYNAME after/before MONTH DAY.
1025     (holiday-hebrew MONTH DAY STRING)  a fixed date on the Hebrew calendar
1026     (holiday-islamic MONTH DAY STRING) a fixed date on the Islamic calendar
1027     (holiday-julian MONTH DAY STRING)  a fixed date on the Julian calendar
1028     (holiday-sexp SEXP STRING) SEXP is a Gregorian-date-valued expression
1029                                in the variable `year'; if it evaluates to
1030                                a visible date, that's the holiday; if it
1031                                evaluates to nil, there's no holiday.  STRING
1032                                is an expression in the variable `date'.
1033
1034 For example, to add Bastille Day, celebrated in France on July 14, add
1035
1036      (holiday-fixed 7 14 \"Bastille Day\")
1037
1038 to the list.  To add Hurricane Supplication Day, celebrated in the Virgin
1039 Islands on the fourth Monday in August, add
1040
1041      (holiday-float 8 1 4 \"Hurricane Supplication Day\")
1042
1043 to the list (the last Monday would be specified with `-1' instead of `4').
1044 To add the last day of Hanukkah to the list, use
1045
1046      (holiday-hebrew 10 2 \"Last day of Hanukkah\")
1047
1048 since the Hebrew months are numbered with 1 starting from Nisan, while to
1049 add the Islamic feast celebrating Mohammed's birthday use
1050
1051      (holiday-islamic 3 12 \"Mohammed's Birthday\")
1052
1053 since the Islamic months are numbered from 1 starting with Muharram.  To
1054 add Thomas Jefferson's birthday, April 2, 1743 (Julian), use
1055
1056      (holiday-julian 4 2 \"Jefferson's Birthday\")
1057
1058 To include a holiday conditionally, use the sexp form or a conditional.  For
1059 example, to include American presidential elections, which occur on the first
1060 Tuesday after the first Monday in November of years divisible by 4, add
1061
1062      (holiday-sexp
1063        (if (zerop (% year 4))
1064            (calendar-gregorian-from-absolute
1065              (1+ (calendar-dayname-on-or-before
1066                    1 (+ 6 (calendar-absolute-from-gregorian
1067                             (list 11 1 year)))))))
1068        \"US Presidential Election\")
1069
1070 or
1071
1072      (if (zerop (% displayed-year 4))
1073          (holiday-fixed 11
1074                 (extract-calendar-day
1075                  (calendar-gregorian-from-absolute
1076                   (1+ (calendar-dayname-on-or-before
1077                        1 (+ 6 (calendar-absolute-from-gregorian
1078                                (list 11 1 displayed-year)))))))
1079                 \"US Presidential Election\"))
1080
1081 to the list.  To include the phases of the moon, add
1082
1083      (lunar-phases)
1084
1085 to the holiday list, where `lunar-phases' is an Emacs-Lisp function that
1086 you've written to return a (possibly empty) list of the relevant VISIBLE dates
1087 with descriptive strings such as
1088
1089      (((2 6 1989) \"New Moon\") ((2 12 1989) \"First Quarter Moon\") ... )."
1090   :type 'sexp
1091   :group 'holidays)
1092
1093 (defconst calendar-buffer "*Calendar*"
1094   "Name of the buffer used for the calendar.")
1095
1096 (defconst holiday-buffer "*Holidays*"
1097   "Name of the buffer used for the displaying the holidays.")
1098
1099 (defconst fancy-diary-buffer "*Fancy Diary Entries*"
1100   "Name of the buffer used for the optional fancy display of the diary.")
1101
1102 (defconst lunar-phases-buffer "*Phases of Moon*"
1103   "Name of the buffer used for the lunar phases.")
1104
1105 (defmacro increment-calendar-month (mon yr n)
1106   "Move the variables MON and YR to the month and year by N months.
1107 Forward if N is positive or backward if N is negative."
1108   (` (let (( macro-y (+ (* (, yr) 12) (, mon) -1 (, n) )))
1109        (setq (, mon) (1+ (% macro-y 12) ))
1110        (setq (, yr) (/ macro-y 12)))))
1111
1112 (defmacro calendar-for-loop (var from init to final do &rest body)
1113   "Execute a for loop."
1114   (` (let (( (, var) (1- (, init)) ))
1115        (while (>= (, final) (setq (, var) (1+ (, var))))
1116          (,@ body)))))
1117
1118 (defmacro calendar-sum (index initial condition expression)
1119   "For INDEX = INITIAL et seq, as long as CONDITION holds, sum EXPRESSION."
1120   (` (let (( (, index) (, initial))
1121              (sum 0))
1122        (while (, condition)
1123          (setq sum (+ sum (, expression) ))
1124          (setq (, index) (1+ (, index))))
1125        sum)))
1126
1127 ;; The following are in-line for speed; they can be called thousands of times
1128 ;; when looking up holidays or processing the diary.  Here, for example, are
1129 ;; the numbers of calls to calendar/diary/holiday functions in preparing the
1130 ;; fancy diary display, for a moderately complex diary file, with functions
1131 ;; used instead of macros.  There were a total of 10000 such calls:
1132 ;;
1133 ;;  1934   extract-calendar-month
1134 ;;  1852   extract-calendar-year
1135 ;;  1819   extract-calendar-day
1136 ;;   845   calendar-leap-year-p
1137 ;;   837   calendar-day-number
1138 ;;   775   calendar-absolute-from-gregorian
1139 ;;   346   calendar-last-day-of-month
1140 ;;   286   hebrew-calendar-last-day-of-month
1141 ;;   188   hebrew-calendar-leap-year-p
1142 ;;   180   hebrew-calendar-elapsed-days
1143 ;;   163   hebrew-calendar-last-month-of-year
1144 ;;    66   calendar-date-compare
1145 ;;    65   hebrew-calendar-days-in-year
1146 ;;    60   calendar-absolute-from-julian
1147 ;;    50   calendar-absolute-from-hebrew
1148 ;;    43   calendar-date-equal
1149 ;;    38   calendar-gregorian-from-absolute
1150 ;;     .
1151 ;;     .
1152 ;;     .
1153 ;;
1154 ;; The use of these seven macros eliminates the overhead of 92% of the function
1155 ;; calls; it's faster this way.
1156
1157 (defsubst extract-calendar-month (date)
1158   "Extract the month part of DATE which has the form (month day year)."
1159   (car date))
1160
1161 (defsubst extract-calendar-day (date)
1162   "Extract the day part of DATE which has the form (month day year)."
1163   (car (cdr date)))
1164
1165 (defsubst extract-calendar-year (date)
1166   "Extract the year part of DATE which has the form (month day year)."
1167   (car (cdr (cdr date))))
1168
1169 (defsubst calendar-leap-year-p (year)
1170   "Returns t if YEAR is a Gregorian leap year."
1171   (and (zerop (% year 4))
1172        (or (not (zerop (% year 100)))
1173            (zerop (% year 400)))))
1174
1175 ;; The foregoing is a bit faster, but not as clear as the following:
1176 ;;
1177 ;;(defsubst calendar-leap-year-p (year)
1178 ;;  "Returns t if YEAR is a Gregorian leap year."
1179 ;;  (or
1180 ;;    (and (=  (% year   4) 0)
1181 ;;         (/= (% year 100) 0))
1182 ;;    (= (% year 400) 0)))
1183
1184 (defsubst calendar-last-day-of-month (month year)
1185   "The last day in MONTH during YEAR."
1186   (if (and (= month 2) (calendar-leap-year-p year))
1187       29
1188     (aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month))))
1189
1190 ;; An explanation of the calculation can be found in PascAlgorithms by
1191 ;; Edward and Ruth Reingold, Scott-Foresman/Little, Brown, 1988.
1192
1193 (defsubst calendar-day-number (date)
1194   "Return the day number within the year of the date DATE.
1195 For example, (calendar-day-number '(1 1 1987)) returns the value 1,
1196 while (calendar-day-number '(12 31 1980)) returns 366."
1197     (let* ((month (extract-calendar-month date))
1198            (day (extract-calendar-day date))
1199            (year (extract-calendar-year date))
1200          (day-of-year (+ day (* 31 (1- month)))))
1201       (if (> month 2)
1202           (progn
1203             (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
1204             (if (calendar-leap-year-p year)
1205                 (setq day-of-year (1+ day-of-year)))))
1206       day-of-year))
1207
1208 (defsubst calendar-absolute-from-gregorian (date)
1209   "The number of days elapsed between the Gregorian date 12/31/1 BC and DATE.
1210 The Gregorian date Sunday, December 31, 1 BC is imaginary."
1211   (let ((prior-years (1- (extract-calendar-year date))))
1212     (+ (calendar-day-number date);; Days this year
1213        (* 365 prior-years);;        + Days in prior years
1214        (/ prior-years 4);;          + Julian leap years
1215        (- (/ prior-years 100));;    - century years
1216        (/ prior-years 400))));;     + Gregorian leap years
1217
1218 (autoload 'calendar-goto-today "cal-move"
1219   "Reposition the calendar window so the current date is visible."
1220   t)
1221
1222 (autoload 'calendar-forward-month "cal-move"
1223   "Move the cursor forward ARG months."
1224   t)
1225
1226 (autoload 'calendar-forward-year "cal-move"
1227   "Move the cursor forward by ARG years."
1228   t)
1229
1230 (autoload 'calendar-backward-month "cal-move"
1231   "Move the cursor backward by ARG months."
1232   t)
1233
1234 (autoload 'calendar-backward-year "cal-move"
1235   "Move the cursor backward ARG years."
1236   t)
1237
1238 (autoload 'scroll-calendar-left "cal-move"
1239   "Scroll the displayed calendar left by ARG months."
1240   t)
1241
1242 (autoload 'scroll-calendar-right "cal-move"
1243   "Scroll the displayed calendar window right by ARG months."
1244   t)
1245
1246 (autoload 'scroll-calendar-left-three-months "cal-move"
1247   "Scroll the displayed calendar window left by 3*ARG months."
1248   t)
1249
1250 (autoload 'scroll-calendar-right-three-months "cal-move"
1251   "Scroll the displayed calendar window right by 3*ARG months."
1252   t)
1253
1254 (autoload 'calendar-cursor-to-nearest-date "cal-move"
1255   "Move the cursor to the closest date."
1256   t)
1257
1258 (autoload 'calendar-forward-day "cal-move"
1259   "Move the cursor forward ARG days."
1260   t)
1261
1262 (autoload 'calendar-backward-day "cal-move"
1263   "Move the cursor back ARG days."
1264   t)
1265
1266 (autoload 'calendar-forward-week "cal-move"
1267   "Move the cursor forward ARG weeks."
1268   t)
1269
1270 (autoload 'calendar-backward-week "cal-move"
1271   "Move the cursor back ARG weeks."
1272   t)
1273
1274 (autoload 'calendar-beginning-of-week "cal-move"
1275   "Move the cursor back ARG calendar-week-start-day's."
1276   t)
1277
1278 (autoload 'calendar-end-of-week "cal-move"
1279   "Move the cursor forward ARG calendar-week-start-day+6's."
1280   t)
1281
1282 (autoload 'calendar-beginning-of-month "cal-move"
1283   "Move the cursor backward ARG month beginnings."
1284   t)
1285
1286 (autoload 'calendar-end-of-month "cal-move"
1287   "Move the cursor forward ARG month ends."
1288   t)
1289
1290 (autoload 'calendar-beginning-of-year "cal-move"
1291   "Move the cursor backward ARG year beginnings."
1292   t)
1293
1294 (autoload 'calendar-end-of-year "cal-move"
1295   "Move the cursor forward ARG year beginnings."
1296   t)
1297
1298 (autoload 'calendar-cursor-to-visible-date "cal-move"
1299   "Move the cursor to DATE that is on the screen."
1300   t)
1301
1302 (autoload 'calendar-goto-date "cal-move"
1303   "Move cursor to DATE."
1304   t)
1305
1306 (autoload 'calendar-one-frame-setup "cal-x"
1307   "Start calendar and display it in a dedicated frame together with the diary.")
1308
1309 (autoload 'calendar-two-frame-setup "cal-x"
1310   "Start calendar and diary in separate, dedicated frames.")
1311
1312 ;;;###autoload
1313 (defvar calendar-setup nil
1314   "The frame set up of the calendar.
1315 The choices are `one-frame' (calendar and diary together in one separate,
1316 dedicated frame) or `two-frames' (calendar and diary in separate, dedicated
1317 frames); with any other value the current frame is used.")
1318
1319 ;;;###autoload
1320 (defun calendar (&optional arg)
1321   "Choose between the one frame, two frame, or basic calendar displays.
1322 The original function `calendar' has been renamed `calendar-basic-setup'."
1323   (interactive "P")
1324   (cond ((equal calendar-setup 'one-frame) (calendar-one-frame-setup arg))
1325         ((equal calendar-setup 'two-frames) (calendar-two-frame-setup arg))
1326         (t (calendar-basic-setup arg))))
1327
1328 (defun calendar-basic-setup (&optional arg)
1329   "Display a three-month calendar in another window.
1330 The three months appear side by side, with the current month in the middle
1331 surrounded by the previous and next months.  The cursor is put on today's date.
1332
1333 If called with an optional prefix argument, prompts for month and year.
1334
1335 This function is suitable for execution in a .emacs file; appropriate setting
1336 of the variable `view-diary-entries-initially' will cause the diary entries for
1337 the current date to be displayed in another window.  The value of the variable
1338 `number-of-diary-entries' controls the number of days of diary entries
1339 displayed upon initial display of the calendar.
1340
1341 An optional prefix argument ARG causes the calendar displayed to be ARG
1342 months in the future if ARG is positive or in the past if ARG is negative;
1343 in this case the cursor goes on the first day of the month.
1344
1345 Once in the calendar window, future or past months can be moved into view.
1346 Arbitrary months can be displayed, or the calendar can be scrolled forward
1347 or backward.
1348
1349 The cursor can be moved forward or backward by one day, one week, one month,
1350 or one year.  All of these commands take prefix arguments which, when negative,
1351 cause movement in the opposite direction.  For convenience, the digit keys
1352 and the minus sign are automatically prefixes.  The window is replotted as
1353 necessary to display the desired date.
1354
1355 Diary entries can be marked on the calendar or displayed in another window.
1356
1357 Use M-x describe-mode for details of the key bindings in the calendar window.
1358
1359 The Gregorian calendar is assumed.
1360
1361 After loading the calendar, the hooks given by the variable
1362 `calendar-load-hook' are run.  This is the place to add key bindings to the
1363 calendar-mode-map.
1364
1365 After preparing the calendar window initially, the hooks given by the variable
1366 `initial-calendar-window-hook' are run.
1367
1368 The hooks given by the variable `today-visible-calendar-hook' are run
1369 every time the calendar window gets scrolled, if the current date is visible
1370 in the window.  If it is not visible, the hooks given by the variable
1371 `today-invisible-calendar-hook' are run.  Thus, for example, setting
1372 `today-visible-calendar-hook' to 'calendar-star-date will cause today's date
1373 to be replaced by asterisks to highlight it whenever it is in the window."
1374   (interactive "P")
1375   (set-buffer (get-buffer-create calendar-buffer))
1376   (calendar-mode)
1377   (let* ((pop-up-windows t)
1378          (split-height-threshold 1000)
1379          (date (if arg
1380                    (calendar-read-date t)
1381                  (calendar-current-date)))
1382          (month (extract-calendar-month date))
1383          (year (extract-calendar-year date)))
1384     (pop-to-buffer calendar-buffer)
1385     (increment-calendar-month month year (- calendar-offset))
1386     (generate-calendar-window month year)
1387     (if (and view-diary-entries-initially (calendar-date-is-visible-p date))
1388         (view-diary-entries
1389          (if (vectorp number-of-diary-entries)
1390              (aref number-of-diary-entries (calendar-day-of-week date))
1391            number-of-diary-entries))))
1392   (let* ((diary-buffer (get-file-buffer diary-file))
1393          (diary-window (if diary-buffer (get-buffer-window diary-buffer)))
1394          (split-height-threshold (if diary-window 2 1000)))
1395     (if view-calendar-holidays-initially
1396         (list-calendar-holidays)))
1397   (run-hooks 'initial-calendar-window-hook))
1398
1399 (autoload 'view-diary-entries "diary-lib"
1400   "Prepare and display a buffer with diary entries.
1401 Searches your diary file for entries that match ARG days starting with
1402 the date indicated by the cursor position in the displayed three-month
1403 calendar."
1404   t)
1405
1406 (autoload 'calendar-sunrise-sunset "solar"
1407   "Local time of sunrise and sunset for date under cursor."
1408   t)
1409
1410 (autoload 'calendar-phases-of-moon "lunar"
1411   "Create a buffer of the phases of the moon for the current calendar window."
1412   t)
1413
1414 (autoload 'calendar-print-french-date "cal-french"
1415   "Show the French Revolutionary calendar equivalent of the date under the cursor."
1416   t)
1417
1418 (autoload 'calendar-goto-french-date "cal-french"
1419  "Move cursor to French Revolutionary date."
1420   t)
1421
1422 (autoload 'calendar-french-date-string "cal-french"
1423   "String of French Revolutionary date of Gregorian date."
1424   t)
1425
1426 (autoload 'calendar-mayan-date-string "cal-mayan"
1427   "String of Mayan date of Gregorian date."
1428   t)
1429
1430 (autoload 'calendar-print-mayan-date "cal-mayan"
1431   "Show the Mayan long count, Tzolkin, and Haab equivalents of the date under the cursor."
1432   t)
1433
1434 (autoload 'calendar-goto-mayan-long-count-date "cal-mayan"
1435  "Move cursor to Mayan long count date."
1436   t)
1437
1438 (autoload 'calendar-next-haab-date "cal-mayan"
1439   "Move cursor to next instance of Mayan Haab date."
1440   t)
1441
1442 (autoload 'calendar-previous-haab-date "cal-mayan"
1443   "Move cursor to previous instance of Mayan Haab date."
1444   t)
1445
1446 (autoload 'calendar-next-tzolkin-date "cal-mayan"
1447   "Move cursor to next instance of Mayan Tzolkin date."
1448   t)
1449
1450 (autoload 'calendar-previous-tzolkin-date "cal-mayan"
1451   "Move cursor to previous instance of Mayan Tzolkin date."
1452   t)
1453
1454 (autoload 'calendar-next-calendar-round-date "cal-mayan"
1455   "Move cursor to next instance of Mayan Haab/Tzolkin combination."
1456   t)
1457
1458 (autoload 'calendar-previous-calendar-round-date "cal-mayan"
1459   "Move cursor to previous instance of Mayan Haab/Tzolkin combination."
1460   t)
1461
1462 (autoload 'calendar-goto-chinese-date "cal-china"
1463    "Move cursor to Chinese date."
1464    t)
1465
1466 (autoload 'calendar-print-chinese-date "cal-china"
1467  "Show the Chinese date equivalents of date."
1468  t)
1469
1470 (autoload 'calendar-chinese-date-string "cal-china"
1471   "String of Chinese date of Gregorian date."
1472   t)
1473
1474 (autoload 'calendar-absolute-from-astro
1475   "Absolute date of astronomical (Julian) day number D."
1476   "cal-julian")
1477
1478 (autoload 'calendar-astro-from-absolute "cal-julian"
1479   "Astronomical (Julian) day number of absolute date D.")
1480
1481 (autoload 'calendar-astro-date-string "cal-julian"
1482   "String of astronomical (Julian) day number of Gregorian date."
1483   t)
1484
1485 (autoload 'calendar-goto-astro-date "cal-julian"
1486    "Move cursor to astronomical (Julian) day number."
1487    t)
1488
1489 (autoload 'calendar-julian-from-absolute "cal-julian"
1490   "Compute the Julian (month day year) corresponding to the absolute DATE.
1491 The absolute date is the number of days elapsed since the (imaginary)
1492 Gregorian date Sunday, December 31, 1 BC.")
1493
1494 (autoload 'calendar-goto-julian-date "cal-julian"
1495   "Move cursor to Julian DATE; echo Julian date unless NOECHO is t."
1496   t)
1497
1498 (autoload 'calendar-julian-date-string "cal-julian"
1499   "String of Julian date of Gregorian DATE.
1500 Defaults to today's date if DATE is not given.
1501 Driven by the variable `calendar-date-display-form'."
1502   t)
1503
1504 (autoload 'calendar-goto-iso-date "cal-iso"
1505   "Move cursor to ISO date."
1506   t)
1507
1508 (autoload 'calendar-print-iso-date "cal-iso"
1509   "Show the ISO date equivalents of date."
1510   t)
1511
1512 (autoload 'calendar-iso-date-string "cal-iso"
1513   "String of ISO date of Gregorian date."
1514   t)
1515
1516 (autoload 'calendar-print-islamic-date "cal-islam"
1517   "Show the Islamic date equivalents of date."
1518   t)
1519
1520 (autoload 'calendar-islamic-date-string "cal-islam"
1521   "String of Islamic date of Gregorian date."
1522   t)
1523
1524 (autoload 'calendar-goto-hebrew-date "cal-hebrew"
1525   "Move cursor to Hebrew date date."
1526   t)
1527
1528 (autoload 'calendar-print-hebrew-date "cal-hebrew"
1529   "Show the Hebrew date equivalents of date."
1530   t)
1531
1532 (autoload 'calendar-hebrew-date-string "cal-hebrew"
1533   "String of Hebrew date of Gregorian date."
1534   t)
1535
1536 (autoload 'calendar-goto-coptic-date "cal-coptic"
1537    "Move cursor to Coptic date date."
1538    t)
1539
1540 (autoload 'calendar-print-coptic-date "cal-coptic"
1541  "Show the Coptic date equivalents of date."
1542  t)
1543
1544 (autoload 'calendar-coptic-date-string "cal-coptic"
1545   "String of Coptic date of Gregorian date."
1546   t)
1547
1548 (autoload 'calendar-goto-ethiopic-date "cal-coptic"
1549    "Move cursor to Ethiopic date date."
1550    t)
1551
1552 (autoload 'calendar-print-ethiopic-date "cal-coptic"
1553  "Show the Ethiopic date equivalents of date."
1554  t)
1555
1556 (autoload 'calendar-ethiopic-date-string "cal-coptic"
1557   "String of Ethiopic date of Gregorian date."
1558   t)
1559
1560 (autoload 'calendar-goto-persian-date "cal-persia"
1561    "Move cursor to Persian date date."
1562    t)
1563
1564 (autoload 'calendar-print-persian-date "cal-persia"
1565  "Show the Persian date equivalents of date."
1566  t)
1567
1568 (autoload 'calendar-persian-date-string "cal-persia"
1569   "String of Persian date of Gregorian date."
1570   t)
1571
1572 (autoload 'show-all-diary-entries "diary-lib"
1573   "Show all of the diary entries in the diary file.
1574 This function gets rid of the selective display of the diary file so that
1575 all entries, not just some, are visible.  If there is no diary buffer, one
1576 is created."
1577   t)
1578
1579 (autoload 'mark-diary-entries "diary-lib"
1580   "Mark days in the calendar window that have diary entries.
1581 Each entry in diary file visible in the calendar window is marked."
1582   t)
1583
1584 (autoload 'make-diary-entry "diary-lib"
1585   "Insert a diary entry STRING which may be NONMARKING in FILE."
1586   t)
1587
1588 (autoload 'insert-diary-entry "diary-lib"
1589   "Insert a diary entry for the date indicated by point."
1590   t)
1591
1592 (autoload 'insert-weekly-diary-entry "diary-lib"
1593   "Insert a weekly diary entry for the day of the week indicated by point."
1594   t)
1595
1596
1597 (autoload 'insert-monthly-diary-entry "diary-lib"
1598   "Insert a monthly diary entry for the day of the month indicated by point."
1599   t)
1600
1601 (autoload 'insert-yearly-diary-entry "diary-lib"
1602   "Insert an annual diary entry for the day of the year indicated by point."
1603   t)
1604
1605 (autoload 'insert-anniversary-diary-entry "diary-lib"
1606   "Insert an anniversary diary entry for the date indicated by point."
1607   t)
1608
1609 (autoload 'insert-block-diary-entry "diary-lib"
1610   "Insert a block diary entry for the dates indicated by point and mark."
1611   t)
1612
1613 (autoload 'insert-cyclic-diary-entry "diary-lib"
1614   "Insert a cyclic diary entry starting at the date indicated by point."
1615   t)
1616
1617 (autoload 'insert-hebrew-diary-entry "cal-hebrew"
1618   "Insert a diary entry for the Hebrew date corresponding to the date
1619 indicated by point."
1620   t)
1621
1622 (autoload 'insert-monthly-hebrew-diary-entry "cal-hebrew"
1623   "Insert a monthly diary entry for the day of the Hebrew month corresponding
1624 to the date indicated by point."
1625   t)
1626
1627 (autoload 'insert-yearly-hebrew-diary-entry "cal-hebrew"
1628   "Insert an annual diary entry for the day of the Hebrew year corresponding
1629 to the date indicated by point."
1630   t)
1631
1632 (autoload 'insert-islamic-diary-entry "cal-islam"
1633   "Insert a diary entry for the Islamic date corresponding to the date
1634 indicated by point."
1635   t)
1636
1637 (autoload 'insert-monthly-islamic-diary-entry "cal-islam"
1638   "Insert a monthly diary entry for the day of the Islamic month corresponding
1639 to the date indicated by point."
1640   t)
1641
1642 (autoload 'insert-yearly-islamic-diary-entry "cal-islam"
1643   "Insert an annual diary entry for the day of the Islamic year corresponding
1644 to the date indicated by point."
1645   t)
1646
1647 (autoload 'list-calendar-holidays "holidays"
1648   "Create a buffer containing the holidays for the current calendar window.
1649 The holidays are those in the list `calendar-notable-days'.  Returns t if any
1650 holidays are found, nil if not."
1651   t)
1652
1653 (autoload 'cal-tex-cursor-month "cal-tex"
1654   "Make a buffer with LaTeX commands for the month cursor is on.
1655 Optional prefix argument specifies number of months to be produced.
1656 Calendar is condensed onto one page.")
1657
1658 (autoload 'cal-tex-cursor-month-landscape "cal-tex"
1659   "Make a buffer with LaTeX commands for the month cursor is on.
1660 Optional prefix argument specifies number of months to be produced.")
1661
1662 (autoload 'cal-tex-cursor-day "cal-tex"
1663   "Make a buffer with LaTeX commands for the day cursor is on.")
1664
1665 (autoload 'cal-tex-cursor-week "cal-tex"
1666   "Make a buffer with LaTeX commands for a two-page one-week calendar.
1667 It applies to the week that point is in.
1668 Optional prefix argument specifies number of weeks.
1669 Holidays are included if `cal-tex-holidays' is t.")
1670
1671 (autoload 'cal-tex-cursor-week2 "cal-tex"
1672   "Make a buffer with LaTeX commands for a two-page one-week calendar.
1673 It applies to the week that point is in.
1674 Optional prefix argument specifies number of weeks.
1675 Holidays are included if `cal-tex-holidays' is t.")
1676
1677 (autoload 'cal-tex-cursor-week-iso "cal-tex"
1678   "Make a buffer with LaTeX commands for a one page ISO-style weekly calendar.
1679 Optional prefix argument specifies number of weeks.
1680 Diary entries are included if `cal-tex-diary' is t.
1681 Holidays are included if `cal-tex-holidays' is t.")
1682
1683 (autoload 'cal-tex-cursor-week-monday "cal-tex"
1684   "Make a buffer with LaTeX commands for a two-page one-week calendar.
1685 It applies to the week that point is in, and starts on Monday.
1686 Optional prefix argument specifies number of weeks.
1687 Holidays are included if `cal-tex-holidays' is t.")
1688
1689 (autoload 'cal-tex-cursor-filofax-2week "cal-tex"
1690   "Two-weeks-at-a-glance Filofax style calendar for week indicated by cursor.
1691 Optional prefix argument specifies number of weeks.
1692 Diary entries are included if cal-tex-diary is t.
1693 Holidays are included if `cal-tex-holidays' is t.")
1694
1695 (autoload 'cal-tex-cursor-filofax-week "cal-tex"
1696   "One-week-at-a-glance Filofax style calendar for week indicated by cursor.
1697 Optional prefix argument specifies number of weeks.
1698 Weeks start on Monday.
1699 Diary entries are included if cal-tex-diary is t.
1700 Holidays are included if `cal-tex-holidays' is t.")
1701
1702 (autoload 'cal-tex-cursor-year "cal-tex"
1703   "Make a buffer with LaTeX commands for a year's calendar.
1704 Optional prefix argument specifies number of years.")
1705
1706 (autoload 'cal-tex-cursor-year-landscape "cal-tex"
1707   "Make a buffer with LaTeX commands for a year's calendar (landscape).
1708 Optional prefix argument specifies number of years.")
1709
1710 (autoload 'cal-tex-cursor-filofax-year "cal-tex"
1711   "Make a buffer with LaTeX commands for a year's calendar (Filofax).
1712 Optional prefix argument specifies number of years.")
1713
1714 (autoload 'mark-calendar-holidays "holidays"
1715   "Mark notable days in the calendar window."
1716   t)
1717
1718 (autoload 'calendar-cursor-holidays "holidays"
1719   "Find holidays for the date specified by the cursor in the calendar window."
1720   t)
1721
1722 (defun generate-calendar-window (&optional mon yr)
1723   "Generate the calendar window for the current date.
1724 Or, for optional MON, YR."
1725   (let* ((buffer-read-only nil)
1726          (today (calendar-current-date))
1727          (month (extract-calendar-month today))
1728          (day (extract-calendar-day today))
1729          (year (extract-calendar-year today))
1730          (today-visible
1731           (or (not mon)
1732               (let ((offset (calendar-interval mon yr month year)))
1733                 (and (<= offset 1) (>= offset -1)))))
1734          (day-in-week (calendar-day-of-week today)))
1735     (update-calendar-mode-line)
1736     (if mon
1737         (generate-calendar mon yr)
1738         (generate-calendar month year))
1739     (calendar-cursor-to-visible-date
1740      (if today-visible today (list displayed-month 1 displayed-year)))
1741     (set-buffer-modified-p nil)
1742     (or (one-window-p t)
1743         (/= (frame-width) (window-width))
1744         (shrink-window (- (window-height) 9)))
1745     (sit-for 0)
1746     (and mark-holidays-in-calendar
1747          (mark-calendar-holidays)
1748          (sit-for 0))
1749     (unwind-protect
1750         (if mark-diary-entries-in-calendar (mark-diary-entries))
1751       (if today-visible
1752           (run-hooks 'today-visible-calendar-hook)
1753         (run-hooks 'today-invisible-calendar-hook)))))
1754
1755 (defun generate-calendar (month year)
1756   "Generate a three-month Gregorian calendar centered around MONTH, YEAR."
1757   (if (< (+ month (* 12 (1- year))) 2)
1758       (error "Months before February, 1 AD are not available."))
1759   (setq displayed-month month)
1760   (setq displayed-year year)
1761   (erase-buffer)
1762   (increment-calendar-month month year -1)
1763   (calendar-for-loop i from 0 to 2 do
1764        (generate-calendar-month month year (+ 5 (* 25 i)))
1765        (increment-calendar-month month year 1)))
1766
1767 (defun generate-calendar-month (month year indent)
1768   "Produce a calendar for MONTH, YEAR on the Gregorian calendar.
1769 The calendar is inserted in the buffer starting at the line on which point
1770 is currently located, but indented INDENT spaces.  The indentation is done
1771 from the first character on the line and does not disturb the first INDENT
1772 characters on the line."
1773   (let* ((blank-days;; at start of month
1774           (mod
1775            (- (calendar-day-of-week (list month 1 year))
1776               calendar-week-start-day)
1777            7))
1778          (last (calendar-last-day-of-month month year)))
1779    (goto-char (point-min))
1780    (calendar-insert-indented
1781     (calendar-string-spread
1782      (list (format "%s %d" (calendar-month-name month) year)) ?  20)
1783     indent t)
1784    (calendar-insert-indented "" indent);; Go to proper spot
1785    (calendar-for-loop i from 0 to 6 do
1786       (insert (substring (aref calendar-day-name-array
1787                                (mod (+ calendar-week-start-day i) 7))
1788                          0 2))
1789       (insert " "))
1790    (calendar-insert-indented "" 0 t);; Force onto following line
1791    (calendar-insert-indented "" indent);; Go to proper spot
1792    ;; Add blank days before the first of the month
1793    (calendar-for-loop i from 1 to blank-days do (insert "   "))
1794    ;; Put in the days of the month
1795    (calendar-for-loop i from 1 to last do
1796       (insert (format "%2d " i))
1797       (put-text-property (- (point) 3) (1- (point))
1798                          'mouse-face 'highlight)
1799       (and (zerop (mod (+ i blank-days) 7))
1800            (/= i last)
1801            (calendar-insert-indented "" 0 t)    ;; Force onto following line
1802            (calendar-insert-indented "" indent)))));; Go to proper spot
1803
1804 (defun calendar-insert-indented (string indent &optional newline)
1805   "Insert STRING at column INDENT.
1806 If the optional parameter NEWLINE is t, leave point at start of next line,
1807 inserting a newline if there was no next line; otherwise, leave point after
1808 the inserted text.  Value is always t."
1809   ;; Try to move to that column.
1810   (move-to-column indent)
1811   ;; If line is too short, indent out to that column.
1812   (if (< (current-column) indent)
1813       (indent-to indent))
1814   (insert string)
1815   ;; Advance to next line, if requested.
1816   (if newline
1817       (progn
1818         (end-of-line)
1819         (if (eobp)
1820             (newline)
1821           (forward-line 1))))
1822   t)
1823
1824 (defun redraw-calendar ()
1825   "Redraw the calendar display."
1826   (interactive)
1827   (let ((cursor-date (calendar-cursor-to-date)))
1828     (generate-calendar-window displayed-month displayed-year)
1829     (calendar-cursor-to-visible-date cursor-date)))
1830
1831 (defcustom calendar-debug-sexp nil
1832   "*Turn debugging on when evaluating a sexp in the diary or holiday list."
1833   :type 'boolean
1834   :group 'calendar)
1835
1836 (defvar calendar-mode-map nil)
1837 (if calendar-mode-map
1838     nil
1839   (setq calendar-mode-map (make-sparse-keymap))
1840   (if window-system (require 'cal-menu))
1841   (calendar-for-loop i from 0 to 9 do
1842        (define-key calendar-mode-map (int-to-string i) 'digit-argument))
1843   (let ((l (list 'narrow-to-region 'mark-word 'mark-sexp 'mark-paragraph
1844                  'mark-defun 'mark-whole-buffer 'mark-page
1845                  'downcase-region 'upcase-region 'kill-region
1846                  'copy-region-as-kill 'capitalize-region 'write-region)))
1847     (while l
1848       (substitute-key-definition (car l) 'calendar-not-implemented
1849                                  calendar-mode-map global-map)
1850       (setq l (cdr l))))
1851   (define-key calendar-mode-map "-"     'negative-argument)
1852   (define-key calendar-mode-map "\C-x>" 'scroll-calendar-right)
1853   (define-key calendar-mode-map [prior] 'scroll-calendar-right-three-months)
1854   (define-key calendar-mode-map "\ev"   'scroll-calendar-right-three-months)
1855   (define-key calendar-mode-map "\C-x<" 'scroll-calendar-left)
1856   (define-key calendar-mode-map [next]  'scroll-calendar-left-three-months)
1857   (define-key calendar-mode-map "\C-v"  'scroll-calendar-left-three-months)
1858   (define-key calendar-mode-map "\C-b"  'calendar-backward-day)
1859   (define-key calendar-mode-map "\C-p"  'calendar-backward-week)
1860   (define-key calendar-mode-map "\e{"   'calendar-backward-month)
1861   (define-key calendar-mode-map "\C-x[" 'calendar-backward-year)
1862   (define-key calendar-mode-map "\C-f"  'calendar-forward-day)
1863   (define-key calendar-mode-map "\C-n"  'calendar-forward-week)
1864   (define-key calendar-mode-map [left]  'calendar-backward-day)
1865   (define-key calendar-mode-map [up]    'calendar-backward-week)
1866   (define-key calendar-mode-map [right] 'calendar-forward-day)
1867   (define-key calendar-mode-map [down]  'calendar-forward-week)
1868   (define-key calendar-mode-map "\e}"   'calendar-forward-month)
1869   (define-key calendar-mode-map "\C-x]" 'calendar-forward-year)
1870   (define-key calendar-mode-map "\C-a"  'calendar-beginning-of-week)
1871   (define-key calendar-mode-map "\C-e"  'calendar-end-of-week)
1872   (define-key calendar-mode-map "\ea"   'calendar-beginning-of-month)
1873   (define-key calendar-mode-map "\ee"   'calendar-end-of-month)
1874   (define-key calendar-mode-map "\e<"   'calendar-beginning-of-year)
1875   (define-key calendar-mode-map "\e>"   'calendar-end-of-year)
1876   (define-key calendar-mode-map "\C-@"  'calendar-set-mark)
1877   ;; Many people are used to typing C-SPC and getting C-@.
1878   (define-key calendar-mode-map [?\C-\ ] 'calendar-set-mark)
1879   (define-key calendar-mode-map "\C-x\C-x" 'calendar-exchange-point-and-mark)
1880   (define-key calendar-mode-map "\e=" 'calendar-count-days-region)
1881   (define-key calendar-mode-map "gd"  'calendar-goto-date)
1882   (define-key calendar-mode-map "gj"  'calendar-goto-julian-date)
1883   (define-key calendar-mode-map "ga"  'calendar-goto-astro-day-number)
1884   (define-key calendar-mode-map "gh"  'calendar-goto-hebrew-date)
1885   (define-key calendar-mode-map "gi"  'calendar-goto-islamic-date)
1886   (define-key calendar-mode-map "gC"  'calendar-goto-chinese-date)
1887   (define-key calendar-mode-map "gk"  'calendar-goto-coptic-date)
1888   (define-key calendar-mode-map "ge"  'calendar-goto-ethiopic-date)
1889   (define-key calendar-mode-map "gp"  'calendar-goto-persian-date)
1890   (define-key calendar-mode-map "gc"  'calendar-goto-iso-date)
1891   (define-key calendar-mode-map "gf"  'calendar-goto-french-date)
1892   (define-key calendar-mode-map "gml"  'calendar-goto-mayan-long-count-date)
1893   (define-key calendar-mode-map "gmpc" 'calendar-previous-calendar-round-date)
1894   (define-key calendar-mode-map "gmnc" 'calendar-next-calendar-round-date)
1895   (define-key calendar-mode-map "gmph" 'calendar-previous-haab-date)
1896   (define-key calendar-mode-map "gmnh" 'calendar-next-haab-date)
1897   (define-key calendar-mode-map "gmpt" 'calendar-previous-tzolkin-date)
1898   (define-key calendar-mode-map "gmnt" 'calendar-next-tzolkin-date)
1899   (define-key calendar-mode-map "S"   'calendar-sunrise-sunset)
1900   (define-key calendar-mode-map "M"   'calendar-phases-of-moon)
1901   (define-key calendar-mode-map " "   'scroll-other-window)
1902   (define-key calendar-mode-map "\C-c\C-l" 'redraw-calendar)
1903   (define-key calendar-mode-map "."   'calendar-goto-today)
1904   (define-key calendar-mode-map "o"   'calendar-other-month)
1905   (define-key calendar-mode-map "q"   'exit-calendar)
1906   (define-key calendar-mode-map "a"   'list-calendar-holidays)
1907   (define-key calendar-mode-map "h"   'calendar-cursor-holidays)
1908   (define-key calendar-mode-map "x"   'mark-calendar-holidays)
1909   (define-key calendar-mode-map "u"   'calendar-unmark)
1910   (define-key calendar-mode-map "m"   'mark-diary-entries)
1911   (define-key calendar-mode-map "d"   'view-diary-entries)
1912   (define-key calendar-mode-map "D"   'view-other-diary-entries)
1913   (define-key calendar-mode-map "s"   'show-all-diary-entries)
1914   (define-key calendar-mode-map "pd"  'calendar-print-day-of-year)
1915   (define-key calendar-mode-map "pC"  'calendar-print-chinese-date)
1916   (define-key calendar-mode-map "pk"  'calendar-print-coptic-date)
1917   (define-key calendar-mode-map "pe"  'calendar-print-ethiopic-date)
1918   (define-key calendar-mode-map "pp"  'calendar-print-persian-date)
1919   (define-key calendar-mode-map "pc"  'calendar-print-iso-date)
1920   (define-key calendar-mode-map "pj"  'calendar-print-julian-date)
1921   (define-key calendar-mode-map "pa"  'calendar-print-astro-day-number)
1922   (define-key calendar-mode-map "ph"  'calendar-print-hebrew-date)
1923   (define-key calendar-mode-map "pi"  'calendar-print-islamic-date)
1924   (define-key calendar-mode-map "pf"  'calendar-print-french-date)
1925   (define-key calendar-mode-map "pm"  'calendar-print-mayan-date)
1926   (define-key calendar-mode-map "id"  'insert-diary-entry)
1927   (define-key calendar-mode-map "iw"  'insert-weekly-diary-entry)
1928   (define-key calendar-mode-map "im"  'insert-monthly-diary-entry)
1929   (define-key calendar-mode-map "iy"  'insert-yearly-diary-entry)
1930   (define-key calendar-mode-map "ia"  'insert-anniversary-diary-entry)
1931   (define-key calendar-mode-map "ib"  'insert-block-diary-entry)
1932   (define-key calendar-mode-map "ic"  'insert-cyclic-diary-entry)
1933   (define-key calendar-mode-map "ihd" 'insert-hebrew-diary-entry)
1934   (define-key calendar-mode-map "ihm" 'insert-monthly-hebrew-diary-entry)
1935   (define-key calendar-mode-map "ihy" 'insert-yearly-hebrew-diary-entry)
1936   (define-key calendar-mode-map "iid" 'insert-islamic-diary-entry)
1937   (define-key calendar-mode-map "iim" 'insert-monthly-islamic-diary-entry)
1938   (define-key calendar-mode-map "iiy" 'insert-yearly-islamic-diary-entry)
1939   (define-key calendar-mode-map "?"   'calendar-goto-info-node)
1940   (define-key calendar-mode-map "tm" 'cal-tex-cursor-month)
1941   (define-key calendar-mode-map "tM" 'cal-tex-cursor-month-landscape)
1942   (define-key calendar-mode-map "td" 'cal-tex-cursor-day)
1943   (define-key calendar-mode-map "tw1" 'cal-tex-cursor-week)
1944   (define-key calendar-mode-map "tw2" 'cal-tex-cursor-week2)
1945   (define-key calendar-mode-map "tw3" 'cal-tex-cursor-week-iso)
1946   (define-key calendar-mode-map "tw4" 'cal-tex-cursor-week-monday)
1947   (define-key calendar-mode-map "tfw" 'cal-tex-cursor-filofax-2week)
1948   (define-key calendar-mode-map "tfW" 'cal-tex-cursor-filofax-week)
1949   (define-key calendar-mode-map "tfy" 'cal-tex-cursor-filofax-year)
1950   (define-key calendar-mode-map "ty" 'cal-tex-cursor-year)
1951   (define-key calendar-mode-map "tY" 'cal-tex-cursor-year-landscape))
1952
1953 (defun describe-calendar-mode ()
1954   "Create a help buffer with a brief description of the calendar-mode."
1955   (interactive)
1956   (with-output-to-temp-buffer "*Help*"
1957     (princ
1958      (format
1959       "Calendar Mode:\nFor a complete description, type %s\n%s\n"
1960       (substitute-command-keys
1961        "\\<calendar-mode-map>\\[describe-mode] from within the calendar")
1962       (substitute-command-keys "\\{calendar-mode-map}")))
1963     (save-excursion
1964       (set-buffer standard-output)
1965       (help-mode))
1966     (print-help-return-message)))
1967
1968 ;; Calendar mode is suitable only for specially formatted data.
1969 (put 'calendar-mode 'mode-class 'special)
1970
1971 (defvar calendar-mode-line-format
1972   (list
1973    (substitute-command-keys "\\<calendar-mode-map>\\[scroll-calendar-left]")
1974    "Calendar"
1975    (substitute-command-keys "\\<calendar-mode-map>\\[calendar-goto-info-node] info/\\[calendar-other-month] other/\\[calendar-goto-today] today")
1976    '(calendar-date-string (calendar-current-date) t)
1977    (substitute-command-keys "\\<calendar-mode-map>\\[scroll-calendar-right]"))
1978   "The mode line of the calendar buffer.")
1979
1980 (defun calendar-goto-info-node ()
1981   "Go to the info node for the calendar."
1982   (interactive)
1983   (require 'info)
1984   (let ((where (save-window-excursion
1985                  (Info-find-emacs-command-nodes 'calendar))))
1986     (if (not where)
1987         (error "Couldn't find documentation for the calendar.")
1988       (let (same-window-buffer-names)
1989         (info))
1990       (Info-find-node (car (car where)) (car (cdr (car where)))))))
1991
1992 (defun calendar-mode ()
1993   "A major mode for the calendar window.
1994
1995 For a complete description, type \
1996 \\<calendar-mode-map>\\[calendar-goto-info-node] from within the calendar.
1997
1998 \\<calendar-mode-map>\\{calendar-mode-map}"
1999
2000   (kill-all-local-variables)
2001   (setq major-mode 'calendar-mode)
2002   (setq mode-name "Calendar")
2003   (use-local-map calendar-mode-map)
2004   (setq buffer-read-only t)
2005   (setq indent-tabs-mode nil)
2006   (update-calendar-mode-line)
2007   (make-local-variable 'calendar-mark-ring)
2008   (make-local-variable 'displayed-month);;  Month in middle of window.
2009   (make-local-variable 'displayed-year));;  Year in middle of window.
2010
2011 (defun calendar-string-spread (strings char length)
2012   "Concatenate list of STRINGS separated with copies of CHAR to fill LENGTH.
2013 The effect is like mapconcat but the separating pieces are as balanced as
2014 possible.  Each item of STRINGS is evaluated before concatenation so it can
2015 actually be an expression that evaluates to a string.  If LENGTH is too short,
2016 the STRINGS are just concatenated and the result truncated."
2017 ;; The algorithm is based on equation (3.25) on page 85 of Concrete
2018 ;; Mathematics by Ronald L. Graham, Donald E. Knuth, and Oren Patashnik,
2019 ;; Addison-Wesley, Reading, MA, 1989
2020   (let* ((strings (mapcar 'eval
2021                           (if (< (length strings) 2)
2022                               (append (list "") strings (list ""))
2023                             strings)))
2024          (n (- length (length (apply 'concat strings))))
2025          (m (1- (length strings)))
2026          (s (car strings))
2027          (strings (cdr strings))
2028          (i 0))
2029     (while strings
2030       (setq s (concat s
2031                       (make-string (max 0 (/ (+ n i) m)) char)
2032                       (car strings)))
2033       (setq i (1+ i))
2034       (setq strings (cdr strings)))
2035     (substring s 0 length)))
2036
2037 (defun update-calendar-mode-line ()
2038   "Update the calendar mode line with the current date and date style."
2039   (if (bufferp (get-buffer calendar-buffer))
2040       (save-excursion
2041         (set-buffer calendar-buffer)
2042         (setq mode-line-format
2043               (calendar-string-spread
2044                calendar-mode-line-format ?  (frame-width))))))
2045
2046 (defun calendar-window-list ()
2047   "List of all calendar-related windows."
2048   (let ((calendar-buffers (calendar-buffer-list))
2049         list)
2050     (walk-windows '(lambda (w)
2051                      (if (memq (window-buffer w) calendar-buffers)
2052                          (setq list (cons w list))))
2053                   nil t)
2054     list))
2055
2056 (defun calendar-buffer-list ()
2057   "List of all calendar-related buffers."
2058   (let* ((diary-buffer (get-file-buffer diary-file))
2059          (buffers (list "*Yahrzeits*" lunar-phases-buffer holiday-buffer
2060                         fancy-diary-buffer diary-buffer calendar-buffer))
2061          (buffer-list nil)
2062          b)
2063     (while buffers
2064       (setq b (car buffers))
2065       (setq b (cond ((stringp b) (get-buffer b))
2066                     ((bufferp b) b)
2067                     (t nil)))
2068       (if b (setq buffer-list (cons b buffer-list)))
2069       (setq buffers (cdr buffers)))
2070     buffer-list))
2071
2072 (defun exit-calendar ()
2073   "Get out of the calendar window and hide it and related buffers."
2074   (interactive)
2075   (let* ((diary-buffer (get-file-buffer diary-file)))
2076     (if (and diary-buffer (buffer-modified-p diary-buffer)
2077              (not
2078               (yes-or-no-p
2079                "Diary modified; do you really want to exit the calendar? ")))
2080         (error)
2081       ;; Need to do this multiple times because one time can replace some
2082       ;; calendar-related buffers with other calendar-related buffers
2083       (mapcar (lambda (x)
2084                 (mapcar 'calendar-hide-window (calendar-window-list)))
2085               (calendar-window-list)))))
2086
2087 (defun calendar-hide-window (window)
2088   "Hide WINDOW if it is calendar-related."
2089   (let ((buffer (if (window-live-p window) (window-buffer window))))
2090     (if (memq buffer (calendar-buffer-list))
2091         (cond
2092          ((and window-system
2093                (eq 'icon (cdr (assoc 'visibility
2094                                      (frame-parameters
2095                                       (window-frame window))))))
2096           nil)
2097          ((and window-system (window-dedicated-p window))
2098           (iconify-frame (window-frame window)))
2099          ((not (and (select-window window) (one-window-p window)))
2100           (delete-window window))
2101          (t (set-buffer buffer)
2102             (bury-buffer))))))
2103
2104 (defun calendar-current-date ()
2105   "Returns the current date in a list (month day year)."
2106   (let ((now (decode-time)))
2107     (list (nth 4 now) (nth 3 now) (nth 5 now))))
2108
2109 (defun calendar-cursor-to-date (&optional error)
2110   "Returns a list (month day year) of current cursor position.
2111 If cursor is not on a specific date, signals an error if optional parameter
2112 ERROR is t, otherwise just returns nil."
2113   (let* ((segment (/ (current-column) 25))
2114          (month (% (+ displayed-month segment -1) 12))
2115          (month (if (= 0 month) 12 month))
2116          (year
2117           (cond
2118            ((and (=  12 month) (= segment 0)) (1- displayed-year))
2119            ((and (=   1 month) (= segment 2)) (1+ displayed-year))
2120            (t displayed-year))))
2121     (if (and (looking-at "[ 0-9]?[0-9][^0-9]")
2122              (< 2 (count-lines (point-min) (point))))
2123         (save-excursion
2124           (if (not (looking-at " "))
2125                    (re-search-backward "[^0-9]"))
2126           (list month
2127                 (string-to-int (buffer-substring (1+ (point)) (+ 4 (point))))
2128                 year))
2129       (if (looking-at "\\*")
2130           (save-excursion
2131             (re-search-backward "[^*]")
2132             (if (looking-at ".\\*\\*")
2133                 (list month calendar-starred-day year)
2134               (if error (error "Not on a date!"))))
2135         (if error (error "Not on a date!"))))))
2136
2137 ;; The following version of calendar-gregorian-from-absolute is preferred for
2138 ;; reasons of clarity, BUT it's much slower than the version that follows it.
2139
2140 ;;(defun calendar-gregorian-from-absolute (date)
2141 ;;  "Compute the list (month day year) corresponding to the absolute DATE.
2142 ;;The absolute date is the number of days elapsed since the (imaginary)
2143 ;;Gregorian date Sunday, December 31, 1 BC."
2144 ;;  (let* ((approx (/ date 366));; Approximation from below.
2145 ;;         (year                ;; Search forward from the approximation.
2146 ;;          (+ approx
2147 ;;             (calendar-sum y approx
2148 ;;                 (>= date (calendar-absolute-from-gregorian (list 1 1 (1+ y))))
2149 ;;                  1)))
2150 ;;         (month         ;; Search forward from January.
2151 ;;          (1+ (calendar-sum m 1
2152 ;;                   (> date
2153 ;;                      (calendar-absolute-from-gregorian
2154 ;;                       (list m (calendar-last-day-of-month m year) year)))
2155 ;;                   1)))
2156 ;;         (day           ;; Calculate the day by subtraction.
2157 ;;          (- date
2158 ;;             (1- (calendar-absolute-from-gregorian (list month 1 year))))))
2159 ;;    (list month day year)))
2160
2161 (defun calendar-gregorian-from-absolute (date)
2162   "Compute the list (month day year) corresponding to the absolute DATE.
2163 The absolute date is the number of days elapsed since the (imaginary)
2164 Gregorian date Sunday, December 31, 1 BC."
2165 ;; See the footnote on page 384 of ``Calendrical Calculations, Part II:
2166 ;; Three Historical Calendars'' by E. M. Reingold,  N. Dershowitz, and S. M.
2167 ;; Clamen, Software--Practice and Experience, Volume 23, Number 4
2168 ;; (April, 1993), pages 383-404 for an explanation.
2169   (let* ((d0 (1- date))
2170          (n400 (/ d0 146097))
2171          (d1 (% d0 146097))
2172          (n100 (/ d1 36524))
2173          (d2 (% d1 36524))
2174          (n4 (/ d2 1461))
2175          (d3 (% d2 1461))
2176          (n1 (/ d3 365))
2177          (day (1+ (% d3 365)))
2178          (year (+ (* 400 n400) (* 100 n100) (* n4 4) n1)))
2179     (if (or (= n100 4) (= n1 4))
2180         (list 12 31 year)
2181       (let ((year (1+ year))
2182             (month 1))
2183         (while (let ((mdays (calendar-last-day-of-month month year)))
2184                  (and (< mdays day)
2185                       (setq day (- day mdays))))
2186           (setq month (1+ month)))
2187         (list month day year)))))
2188
2189 (defun calendar-other-month (month year)
2190   "Display a three-month calendar centered around MONTH and YEAR."
2191   (interactive (calendar-read-date 'noday))
2192   (if (and (= month displayed-month)
2193            (= year displayed-year))
2194       nil
2195     (let ((old-date (calendar-cursor-to-date))
2196           (today (calendar-current-date)))
2197       (generate-calendar-window month year)
2198       (calendar-cursor-to-visible-date
2199        (cond
2200         ((calendar-date-is-visible-p old-date) old-date)
2201         ((calendar-date-is-visible-p today) today)
2202         (t (list month 1 year)))))))
2203
2204 (defun calendar-set-mark (arg)
2205   "Mark the date under the cursor, or jump to marked date.
2206 With no prefix argument, push current date onto marked date ring.
2207 With argument, jump to mark, pop it, and put point at end of ring."
2208   (interactive "P")
2209   (let ((date (calendar-cursor-to-date t)))
2210     (if (null arg)
2211         (progn
2212           (setq calendar-mark-ring (cons date calendar-mark-ring))
2213           ;; Since the top of the mark ring is the marked date in the
2214           ;; calendar, the mark ring in the calendar is one longer than
2215           ;; in other buffers to get the same effect.
2216           (if (> (length calendar-mark-ring) (1+ mark-ring-max))
2217               (setcdr (nthcdr mark-ring-max calendar-mark-ring) nil))
2218           (message "Mark set"))
2219       (if (null calendar-mark-ring)
2220           (error "No mark set in this buffer")
2221         (calendar-goto-date (car calendar-mark-ring))
2222         (setq calendar-mark-ring
2223               (cdr (nconc calendar-mark-ring (list date))))))))
2224
2225 (defun calendar-exchange-point-and-mark ()
2226   "Exchange the current cursor position with the marked date."
2227   (interactive)
2228   (let ((mark (car calendar-mark-ring))
2229         (date (calendar-cursor-to-date t)))
2230     (if (null mark)
2231         (error "No mark set in this buffer")
2232       (setq calendar-mark-ring (cons date (cdr calendar-mark-ring)))
2233       (calendar-goto-date mark))))
2234
2235 (defun calendar-count-days-region ()
2236   "Count the number of days (inclusive) between point and the mark."
2237   (interactive)
2238   (let* ((days (- (calendar-absolute-from-gregorian
2239                    (calendar-cursor-to-date t))
2240                   (calendar-absolute-from-gregorian
2241                    (or (car calendar-mark-ring)
2242                        (error "No mark set in this buffer")))))
2243          (days (1+ (if (> days 0) days (- days)))))
2244     (message "Region has %d day%s (inclusive)"
2245              days (if (> days 1) "s" ""))))
2246
2247 (defun calendar-not-implemented ()
2248   "Not implemented."
2249   (interactive)
2250   (error "%s not available in the calendar"
2251          (global-key-binding (this-command-keys))))
2252
2253 (defun calendar-read (prompt acceptable &optional initial-contents)
2254   "Return an object read from the minibuffer.
2255 Prompt with the string PROMPT and use the function ACCEPTABLE to decide if
2256 entered item is acceptable.  If non-nil, optional third arg INITIAL-CONTENTS
2257 is a string to insert in the minibuffer before reading."
2258   (let ((value (read-minibuffer prompt initial-contents)))
2259     (while (not (funcall acceptable value))
2260       (setq value (read-minibuffer prompt initial-contents)))
2261     value))
2262
2263 (defun calendar-read-date (&optional noday)
2264   "Prompt for Gregorian date.  Returns a list (month day year).
2265 If optional NODAY is t, does not ask for day, but just returns
2266 (month nil year); if NODAY is any other non-nil value the value returned is
2267 (month year) "
2268   (let* ((year (calendar-read
2269                 "Year (>0): "
2270                 '(lambda (x) (> x 0))
2271                 (int-to-string (extract-calendar-year
2272                                 (calendar-current-date)))))
2273          (month-array calendar-month-name-array)
2274          (completion-ignore-case t)
2275          (month (cdr (assoc
2276                       (capitalize
2277                        (completing-read
2278                         "Month name: "
2279                         (mapcar 'list (append month-array nil))
2280                         nil t))
2281                       (calendar-make-alist month-array 1 'capitalize))))
2282          (last (calendar-last-day-of-month month year)))
2283     (if noday
2284         (if (eq noday t)
2285             (list month nil year)
2286           (list month year))
2287       (list month
2288             (calendar-read (format "Day (1-%d): " last)
2289                                    '(lambda (x) (and (< 0 x) (<= x last))))
2290             year))))
2291
2292 (defun calendar-interval (mon1 yr1 mon2 yr2)
2293   "The number of months difference between MON1, YR1 and MON2, YR2."
2294   (+ (* 12 (- yr2 yr1))
2295      (- mon2 mon1)))
2296
2297 (defun calendar-day-name (date)
2298   "Returns a string with the name of the day of the week of DATE."
2299   (aref calendar-day-name-array (calendar-day-of-week date)))
2300
2301 (defvar calendar-day-name-array
2302   ["Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"])
2303
2304 (defvar calendar-month-name-array
2305   ["January" "February" "March"     "April"   "May"      "June"
2306    "July"    "August"   "September" "October" "November" "December"])
2307
2308 (defun calendar-make-alist (sequence &optional start-index filter)
2309   "Make an assoc list corresponding to SEQUENCE.
2310 Start at index 1, unless optional START-INDEX is provided.
2311 If FILTER is provided, apply it to each item in the list."
2312   (let ((index (if start-index (1- start-index) 0)))
2313     (mapcar
2314      '(lambda (x)
2315         (setq index (1+ index))
2316         (cons (if filter (funcall filter x) x)
2317               index))
2318      (append sequence nil))))
2319
2320 (defun calendar-month-name (month)
2321   "The name of MONTH."
2322   (aref calendar-month-name-array (1- month)))
2323
2324 (defun calendar-day-of-week (date)
2325   "Returns the day-of-the-week index of DATE, 0 for Sunday, 1 for Monday, etc."
2326   (% (calendar-absolute-from-gregorian date) 7))
2327
2328 (defun calendar-unmark ()
2329   "Delete all diary/holiday marks/highlighting from the calendar."
2330   (interactive)
2331   (setq mark-holidays-in-calendar nil)
2332   (setq mark-diary-entries-in-calendar nil)
2333   (redraw-calendar))
2334
2335 (defun calendar-date-is-visible-p (date)
2336   "Returns t if DATE is legal and is visible in the calendar window."
2337   (let ((gap (calendar-interval
2338               displayed-month displayed-year
2339               (extract-calendar-month date) (extract-calendar-year date))))
2340     (and (calendar-date-is-legal-p date) (> 2 gap) (< -2 gap))))
2341
2342 (defun calendar-date-is-legal-p (date)
2343   "Returns t if DATE is a legal date."
2344   (let ((month (extract-calendar-month date))
2345         (day (extract-calendar-day date))
2346         (year (extract-calendar-year date)))
2347     (and (<= 1 month) (<= month 12)
2348          (<= 1 day) (<= day (calendar-last-day-of-month month year))
2349          (<= 1 year))))
2350
2351 (defun calendar-date-equal (date1 date2)
2352   "Returns t if the DATE1 and DATE2 are the same."
2353   (and
2354    (= (extract-calendar-month date1) (extract-calendar-month date2))
2355    (= (extract-calendar-day date1) (extract-calendar-day date2))
2356    (= (extract-calendar-year date1) (extract-calendar-year date2))))
2357
2358 (defun mark-visible-calendar-date (date &optional mark)
2359   "Mark DATE in the calendar window with MARK.
2360 MARK is either a single-character string or a face.
2361 MARK defaults to diary-entry-marker."
2362   (if (calendar-date-is-legal-p date)
2363       (save-excursion
2364         (set-buffer calendar-buffer)
2365         (calendar-cursor-to-visible-date date)
2366         (let ((mark (or mark diary-entry-marker)))
2367           (if (stringp mark)
2368               (let ((buffer-read-only nil))
2369                 (forward-char 1)
2370                 (delete-char 1)
2371                 (insert mark)
2372                 (forward-char -2))
2373             (overlay-put
2374              (make-overlay (1- (point)) (1+ (point))) 'face mark))))))
2375
2376 (defun calendar-star-date ()
2377   "Replace the date under the cursor in the calendar window with asterisks.
2378 This function can be used with the today-visible-calendar-hook run after the
2379 calendar window has been prepared."
2380   (let ((buffer-read-only nil))
2381     (make-variable-buffer-local 'calendar-starred-day)
2382     (forward-char 1)
2383     (setq calendar-starred-day
2384           (string-to-int
2385            (buffer-substring (point) (- (point) 2))))
2386     (delete-char -2)
2387     (insert "**")
2388     (backward-char 1)
2389     (set-buffer-modified-p nil)))
2390
2391 (defun calendar-mark-today ()
2392   "Mark the date under the cursor in the calendar window.
2393 The date is marked with calendar-today-marker.  This function can be used with
2394 the today-visible-calendar-hook run after the calendar window has been
2395 prepared."
2396   (mark-visible-calendar-date
2397    (calendar-cursor-to-date)
2398    calendar-today-marker))
2399
2400 (defun calendar-date-compare (date1 date2)
2401   "Returns t if DATE1 is before DATE2, nil otherwise.
2402 The actual dates are in the car of DATE1 and DATE2."
2403   (< (calendar-absolute-from-gregorian (car date1))
2404      (calendar-absolute-from-gregorian (car date2))))
2405
2406 (defun calendar-date-string (date &optional abbreviate nodayname)
2407   "A string form of DATE, driven by the variable `calendar-date-display-form'.
2408 An optional parameter ABBREVIATE, when t, causes the month and day names to be
2409 abbreviated to three characters.  An optional parameter NODAYNAME, when t,
2410 omits the name of the day of the week."
2411   (let* ((dayname
2412           (if nodayname
2413               nil
2414             (if abbreviate
2415                 (substring (calendar-day-name date) 0 3)
2416               (calendar-day-name date))))
2417          (month (extract-calendar-month date))
2418          (monthname
2419           (if abbreviate
2420               (substring
2421                (calendar-month-name month) 0 3)
2422             (calendar-month-name month)))
2423          (day (int-to-string (extract-calendar-day date)))
2424          (month (int-to-string month))
2425          (year (int-to-string (extract-calendar-year date))))
2426     (mapconcat 'eval calendar-date-display-form "")))
2427
2428 (defun calendar-dayname-on-or-before (dayname date)
2429   "Returns the absolute date of the DAYNAME on or before absolute DATE.
2430 DAYNAME=0 means Sunday, DAYNAME=1 means Monday, and so on.
2431
2432 Note: Applying this function to d+6 gives us the DAYNAME on or after an
2433 absolute day d.  Similarly, applying it to d+3 gives the DAYNAME nearest to
2434 absolute date d, applying it to d-1 gives the DAYNAME previous to absolute
2435 date d, and applying it to d+7 gives the DAYNAME following absolute date d."
2436   (- date (% (- date dayname) 7)))
2437
2438 (defun calendar-nth-named-absday (n dayname month year &optional day)
2439   "The absolute date of Nth DAYNAME in MONTH, YEAR before/after optional DAY.
2440 A DAYNAME of 0 means Sunday, 1 means Monday, and so on.  If N<0,
2441 return the Nth DAYNAME before MONTH DAY, YEAR (inclusive).
2442 If N>0, return the Nth DAYNAME after MONTH DAY, YEAR (inclusive).
2443
2444 If DAY is omitted, it defaults to 1 if N>0, and MONTH's last day otherwise."
2445   (if (> n 0)
2446       (+ (* 7 (1- n))
2447          (calendar-dayname-on-or-before
2448           dayname
2449           (+ 6 (calendar-absolute-from-gregorian
2450                 (list month (or day 1) year)))))
2451     (+ (* 7 (1+ n))
2452        (calendar-dayname-on-or-before
2453         dayname
2454         (calendar-absolute-from-gregorian
2455          (list month
2456                (or day (calendar-last-day-of-month month year))
2457                year))))))
2458
2459 (defun calendar-nth-named-day (n dayname month year &optional day)
2460   "The date of Nth DAYNAME in MONTH, YEAR before/after optional DAY.
2461 A DAYNAME of 0 means Sunday, 1 means Monday, and so on.  If N<0,
2462 return the Nth DAYNAME before MONTH DAY, YEAR (inclusive).
2463 If N>0, return the Nth DAYNAME after MONTH DAY, YEAR (inclusive).
2464
2465 If DAY is omitted, it defaults to 1 if N>0, and MONTH's last day otherwise."
2466   (calendar-gregorian-from-absolute
2467    (calendar-nth-named-absday n dayname month year day)))
2468
2469 (defun calendar-day-of-year-string (&optional date)
2470   "String of day number of year of Gregorian DATE.
2471 Defaults to today's date if DATE is not given."
2472   (let* ((d (or date (calendar-current-date)))
2473          (year (extract-calendar-year d))
2474          (day (calendar-day-number d))
2475          (days-remaining (- (calendar-day-number (list 12 31 year)) day)))
2476     (format "Day %d of %d; %d day%s remaining in the year"
2477             day year days-remaining (if (= days-remaining 1) "" "s"))))
2478
2479 (defun calendar-print-day-of-year ()
2480   "Show day number in year/days remaining in year for date under the cursor."
2481   (interactive)
2482   (message (calendar-day-of-year-string (calendar-cursor-to-date t))))
2483
2484 (defun calendar-set-mode-line (str)
2485   "Set mode line to STR, centered, surrounded by dashes."
2486   (setq mode-line-format
2487         (calendar-string-spread (list str) ?- (frame-width))))
2488
2489 (defun calendar-mod (m n)
2490   "Non-negative remainder of M/N with N instead of 0."
2491   (1+ (mod (1- m) n)))
2492
2493 (run-hooks 'calendar-load-hook)
2494
2495 (provide 'calendar)
2496
2497 ;;; Local variables:
2498 ;;; byte-compile-dynamic: t
2499 ;;; End:
2500
2501 ;;; calendar.el ends here