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Diffstat (limited to 'lisp/calendar/cal-coptic.el')
-rw-r--r-- | lisp/calendar/cal-coptic.el | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/lisp/calendar/cal-coptic.el b/lisp/calendar/cal-coptic.el new file mode 100644 index 00000000000..04b786ec84c --- /dev/null +++ b/lisp/calendar/cal-coptic.el @@ -0,0 +1,233 @@ +;;; cal-coptic.el --- calendar functions for the Coptic/Ethiopic calendars. + +;; Copyright (C) 1995 Free Software Foundation, Inc. + +;; Author: Edward M. Reingold <reingold@cs.uiuc.edu> +;; Keywords: calendar +;; Human-Keywords: Coptic calendar, Ethiopic calendar, calendar, diary + +;; This file is part of GNU Emacs. + +;; GNU Emacs is free software; you can redistribute it and/or modify +;; it under the terms of the GNU General Public License as published by +;; the Free Software Foundation; either version 2, or (at your option) +;; any later version. + +;; GNU Emacs is distributed in the hope that it will be useful, +;; but WITHOUT ANY WARRANTY; without even the implied warranty of +;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;; GNU General Public License for more details. + +;; You should have received a copy of the GNU General Public License +;; along with GNU Emacs; see the file COPYING. If not, write to +;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + +;;; Commentary: + +;; This collection of functions implements the features of calendar.el and +;; diary.el that deal with the Coptic and Ethiopic calendars. + +;; Comments, corrections, and improvements should be sent to +;; Edward M. Reingold Department of Computer Science +;; (217) 333-6733 University of Illinois at Urbana-Champaign +;; reingold@cs.uiuc.edu 1304 West Springfield Avenue +;; Urbana, Illinois 61801 + +;;; Code: + +(require 'cal-julian) + +(defvar coptic-calendar-month-name-array + ["Tot" "Babe" "Hatur" "Kihak" "Tube" "Amshir" "Baramhat" "Barmuda" + "Bashnas" "Bauna" "Abib" "Misra" "Nisi"]) + +(defvar coptic-calendar-epoch (calendar-absolute-from-julian '(8 29 284)) + "Absolute date of start of Coptic calendar = August 29, 284 A.D. (Julian).") + +(defconst coptic-name "Coptic") + +(defun coptic-calendar-leap-year-p (year) + "True if YEAR is a leap year on the Coptic calendar." + (zerop (mod (1+ year) 4))) + +(defun coptic-calendar-last-day-of-month (month year) + "Return last day of MONTH, YEAR on the Coptic calendar. +The 13th month is not really a month, but the 5 (6 in leap years) day period of +Nisi (Kebus) at the end of the year." + (if (< month 13) + 30 + (if (coptic-calendar-leap-year-p year) + 6 + 5))) + +(defun calendar-absolute-from-coptic (date) + "Compute absolute date from Coptic date DATE. +The absolute date is the number of days elapsed since the (imaginary) +Gregorian date Sunday, December 31, 1 BC." + (let ((month (extract-calendar-month date)) + (day (extract-calendar-day date)) + (year (extract-calendar-year date))) + (+ (1- coptic-calendar-epoch);; Days before start of calendar + (* 365 (1- year)) ;; Days in prior years + (/ year 4) ;; Leap days in prior years + (* 30 (1- month)) ;; Days in prior months this year + day))) ;; Days so far this month + + +(defun calendar-coptic-from-absolute (date) + "Compute the Coptic equivalent for absolute date DATE. +The result is a list of the form (MONTH DAY YEAR). +The absolute date is the number of days elapsed since the imaginary +Gregorian date Sunday, December 31, 1 BC." + (if (< date coptic-calendar-epoch) + (list 0 0 0);; pre-Coptic date + (let* ((approx (/ (- date coptic-calendar-epoch) + 366)) ;; Approximation from below. + (year ;; Search forward from the approximation. + (+ approx + (calendar-sum y approx + (>= date (calendar-absolute-from-coptic (list 1 1 (1+ y)))) + 1))) + (month ;; Search forward from Tot. + (1+ (calendar-sum m 1 + (> date + (calendar-absolute-from-coptic + (list m + (coptic-calendar-last-day-of-month m year) + year))) + 1))) + (day ;; Calculate the day by subtraction. + (- date + (1- (calendar-absolute-from-coptic (list month 1 year)))))) + (list month day year)))) + +(defun calendar-coptic-date-string (&optional date) + "String of Coptic date of Gregorian DATE. +Returns the empty string if DATE is pre-Coptic calendar. +Defaults to today's date if DATE is not given." + (let* ((coptic-date (calendar-coptic-from-absolute + (calendar-absolute-from-gregorian + (or date (calendar-current-date))))) + (y (extract-calendar-year coptic-date)) + (m (extract-calendar-month coptic-date))) + (if (< y 1) + "" + (let ((monthname (aref coptic-calendar-month-name-array (1- m))) + (day (int-to-string (extract-calendar-day coptic-date))) + (dayname nil) + (month (int-to-string m)) + (year (int-to-string y))) + (mapconcat 'eval calendar-date-display-form ""))))) + +(defun calendar-print-coptic-date () + "Show the Coptic calendar equivalent of the selected date." + (interactive) + (let ((f (calendar-coptic-date-string (calendar-cursor-to-date t)))) + (if (string-equal f "") + (message "Date is pre-%s calendar" coptic-name) + (message f)))) + +(defun calendar-goto-coptic-date (date &optional noecho) + "Move cursor to Coptic date DATE. +Echo Coptic date unless NOECHO is t." + (interactive (coptic-prompt-for-date)) + (calendar-goto-date (calendar-gregorian-from-absolute + (calendar-absolute-from-coptic date))) + (or noecho (calendar-print-coptic-date))) + +(defun coptic-prompt-for-date () + "Ask for a Coptic date." + (let* ((today (calendar-current-date)) + (year (calendar-read + (format "%s calendar year (>0): " coptic-name) + '(lambda (x) (> x 0)) + (int-to-string + (extract-calendar-year + (calendar-coptic-from-absolute + (calendar-absolute-from-gregorian today)))))) + (completion-ignore-case t) + (month (cdr (assoc + (capitalize + (completing-read + (format "%s calendar month name: " coptic-name) + (mapcar 'list + (append coptic-calendar-month-name-array nil)) + nil t)) + (calendar-make-alist coptic-calendar-month-name-array + 1 'capitalize)))) + (last (coptic-calendar-last-day-of-month month year)) + (day (calendar-read + (format "%s calendar day (1-%d): " coptic-name last) + '(lambda (x) (and (< 0 x) (<= x last)))))) + (list (list month day year)))) + +(defun diary-coptic-date () + "Coptic calendar equivalent of date diary entry." + (let ((f (calendar-coptic-date-string (calendar-cursor-to-date t)))) + (if (string-equal f "") + (format "Date is pre-%s calendar" coptic-name) + f))) + +(defconst ethiopic-calendar-month-name-array + ["Maskarram" "Tekemt" "Hadar" "Tahsas" "Tarr" "Yekatit" "Magawit" "Miaziah" + "Genbot" "Sanni" "Hamle" "Nas'hi" "Pagnem"]) + +(defconst ethiopic-calendar-epoch (calendar-absolute-from-julian '(8 29 7)) + "Absolute date of start of Ethiopic calendar = August 29, 7 A.D. (Julian).") + +(defconst ethiopic-name "Ethiopic") + +(defun calendar-absolute-from-ethiopic (date) + "Compute absolute date from Ethiopic date DATE. +The absolute date is the number of days elapsed since the (imaginary) +Gregorian date Sunday, December 31, 1 BC." + (let ((coptic-calendar-epoch ethiopic-calendar-epoch)) + (calendar-absolute-from-coptic date))) + +(defun calendar-ethiopic-from-absolute (date) + "Compute the Ethiopic equivalent for absolute date DATE. +The result is a list of the form (MONTH DAY YEAR). +The absolute date is the number of days elapsed since the imaginary +Gregorian date Sunday, December 31, 1 BC." + (let ((coptic-calendar-epoch ethiopic-calendar-epoch)) + (calendar-coptic-from-absolute date))) + +(defun calendar-ethiopic-date-string (&optional date) + "String of Ethiopic date of Gregorian DATE. +Returns the empty string if DATE is pre-Ethiopic calendar. +Defaults to today's date if DATE is not given." + (let ((coptic-calendar-epoch ethiopic-calendar-epoch) + (coptic-name ethiopic-name) + (coptic-calendar-month-name-array ethiopic-calendar-month-name-array)) + (calendar-coptic-date-string date))) + +(defun calendar-print-ethiopic-date () + "Show the Ethiopic calendar equivalent of the selected date." + (interactive) + (let ((coptic-calendar-epoch ethiopic-calendar-epoch) + (coptic-name ethiopic-name) + (coptic-calendar-month-name-array ethiopic-calendar-month-name-array)) + (call-interactively 'calendar-print-coptic-date))) + +(defun calendar-goto-ethiopic-date (date &optional noecho) + "Move cursor to Ethiopic date DATE. +Echo Ethiopic date unless NOECHO is t." + (interactive + (let ((coptic-calendar-epoch ethiopic-calendar-epoch) + (coptic-name ethiopic-name) + (coptic-calendar-month-name-array ethiopic-calendar-month-name-array)) + (coptic-prompt-for-date))) + (calendar-goto-date (calendar-gregorian-from-absolute + (calendar-absolute-from-ethiopic date))) + (or noecho (calendar-print-ethiopic-date))) + +(defun diary-ethiopic-date () + "Ethiopic calendar equivalent of date diary entry." + (let ((coptic-calendar-epoch ethiopic-calendar-epoch) + (coptic-name ethiopic-name) + (coptic-calendar-month-name-array ethiopic-calendar-month-name-array)) + (diary-coptic-date))) + +(provide 'cal-coptic) + +;;; cal-coptic.el ends here |