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(holiday-easter-etc): Make arguments optional for backwards

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compatability.  Doc fix.  Remove un-necessary local vars mandatory,
output-list.
This commit is contained in:
Glenn Morris 2004-12-07 00:46:08 +00:00
parent c9ba50dd01
commit 3cd74de74c
1 changed files with 58 additions and 26 deletions
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84
lisp/calendar/holidays.el
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@ -414,32 +414,64 @@ date. If date is nil, or if the date is not visible, there is no holiday."
(if (calendar-date-is-visible-p advent)
(list (list advent string))))))
(defun holiday-easter-etc (n string)
"Date of Nth day after Easter (named STRING), if visible in calendar window."
(let* ((century (1+ (/ displayed-year 100)))
(shifted-epact ;; Age of moon for April 5...
(% (+ 14 (* 11 (% displayed-year 19));; ...by Nicaean rule
(- ;; ...corrected for the Gregorian century rule
(/ (* 3 century) 4))
(/ ;; ...corrected for Metonic cycle inaccuracy.
(+ 5 (* 8 century)) 25)
(* 30 century));; Keeps value positive.
30))
(adjusted-epact ;; Adjust for 29.5 day month.
(if (or (= shifted-epact 0)
(and (= shifted-epact 1) (< 10 (% displayed-year 19))))
(1+ shifted-epact)
shifted-epact))
(paschal-moon ;; Day after the full moon on or after March 21.
(- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
adjusted-epact))
(abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7)))
(mandatory
(list
(list (calendar-gregorian-from-absolute (+ abs-easter n))
string)))
(output-list (filter-visible-calendar-holidays mandatory)))
output-list))
(defun holiday-easter-etc (&optional n string)
"Date of Nth day after Easter (named STRING), if visible in calendar window.
Negative values of N are interpreted as days before Easter.
STRING is used purely for display purposes. The return value has
the form ((MONTH DAY YEAR) STRING), where the date is that of the
Nth day before or after Easter.
For backwards compatability, if this function is called with no
arguments, then it returns a list of \"standard\" Easter-related
holidays (with more entries if `all-christian-calendar-holidays'
is non-nil)."
;; Backwards compatability layer.
(if (not n)
(let (res-list res)
(dolist (elem (append
(if all-christian-calendar-holidays
'((-63 . "Septuagesima Sunday")
(-56 . "Sexagesima Sunday")
(-49 . "Shrove Sunday")
(-48 . "Shrove Monday")
(-47 . "Shrove Tuesday")
(-14 . "Passion Sunday")
(-7 . "Palm Sunday")
(-3 . "Maundy Thursday")
(35 . "Rogation Sunday")
(39 . "Ascension Day")
(49 . "Pentecost (Whitsunday)")
(50 . "Whitmonday")
(56 . "Trinity Sunday")
(60 . "Corpus Christi")))
'((0 . "Easter Sunday")
(-2 . "Good Friday")
(-46 . "Ash Wednesday")))
res-list)
;; Filter out nil (not visible) values.
(if (setq res (holiday-easter-etc (car elem) (cdr elem)))
(setq res-list (append res res-list)))))
(let* ((century (1+ (/ displayed-year 100)))
(shifted-epact ;; Age of moon for April 5...
(% (+ 14 (* 11 (% displayed-year 19)) ;; ...by Nicaean rule
(- ;; ...corrected for the Gregorian century rule
(/ (* 3 century) 4))
(/ ;; ...corrected for Metonic cycle inaccuracy.
(+ 5 (* 8 century)) 25)
(* 30 century)) ;; Keeps value positive.
30))
(adjusted-epact ;; Adjust for 29.5 day month.
(if (or (zerop shifted-epact)
(and (= shifted-epact 1) (< 10 (% displayed-year 19))))
(1+ shifted-epact)
shifted-epact))
(paschal-moon ;; Day after the full moon on or after March 21.
(- (calendar-absolute-from-gregorian (list 4 19 displayed-year))
adjusted-epact))
(abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7))))
(filter-visible-calendar-holidays
(list (list (calendar-gregorian-from-absolute (+ abs-easter n))
string))))))
(defun holiday-greek-orthodox-easter ()
"Date of Easter according to the rule of the Council of Nicaea."