Commit 06e9110e authored by Glenn Morris's avatar Glenn Morris
Browse files

(calendar-bahai-leap-year-p)

(calendar-bahai-leap-base, calendar-bahai-from-absolute): Doc fixes.
(calendar-absolute-from-bahai): Fix the leap-year case.
(calendar-bahai-from-absolute): Store the month.
(calendar-bahai-date-string, calendar-bahai-print-date): Handle
pre-Bahai dates.
parent 01633b01
......@@ -67,12 +67,13 @@
"Absolute date of start of Bahá'í calendar = March 19, 622 AD (Julian).")
(defun calendar-bahai-leap-year-p (year)
"True if YEAR is a leap year on the Bahá'í calendar."
"True if Bahá'í YEAR is a leap year in the Bahá'í calendar."
(calendar-leap-year-p (+ year 1844)))
(defconst calendar-bahai-leap-base
(+ (/ 1844 4) (- (/ 1844 100)) (/ 1844 400))
"Used by `calendar-absolute-from-bahai'.")
"Number of leap years between 1 and 1844 AD, inclusive.
Used by `calendar-absolute-from-bahai'.")
(defun calendar-absolute-from-bahai (date)
"Compute absolute date from Bahá'í date DATE.
......@@ -90,24 +91,25 @@ Gregorian date Sunday, December 31, 1 BC."
(* 365 (1- year)) ; days in prior years
leap-days
(calendar-sum m 1 (< m month) 19)
(if (= month 19) 4 0)
(if (= month 19)
(if (calendar-bahai-leap-year-p year) 5 4)
0)
day))) ; days so far this month
(defun calendar-bahai-from-absolute (date)
"Bahá'í year corresponding to the absolute DATE."
"Bahá'í date (month day year) corresponding to the absolute DATE."
(if (< date calendar-bahai-epoch)
(list 0 0 0) ; pre-Bahá'í date
(let* ((greg (calendar-gregorian-from-absolute date))
(gmonth (extract-calendar-month greg))
(year (+ (- (extract-calendar-year greg) 1844)
(if (or (> (extract-calendar-month greg) 3)
(and (= (extract-calendar-month greg) 3)
(if (or (> gmonth 3)
(and (= gmonth 3)
(>= (extract-calendar-day greg) 21)))
1 0)))
(month ; search forward from Baha
(1+ (calendar-sum m 1
(> date
(calendar-absolute-from-bahai
(list m 19 year)))
(> date (calendar-absolute-from-bahai (list m 19 year)))
1)))
(day ; calculate the day by subtraction
(- date
......@@ -130,21 +132,24 @@ Defaults to today's date if DATE is not given."
(aref calendar-bahai-month-name-array (1- m))))
(day (int-to-string
(if (<= d 0)
(if (calendar-bahai-leap-year-p y)
(+ d 5)
(+ d 4))
(+ d (if (calendar-bahai-leap-year-p y) 5 4))
d)))
(year (int-to-string y))
(month (int-to-string m))
dayname)
(mapconcat 'eval calendar-date-display-form "")))
(if (< y 1)
""
;; Can't call calendar-date-string because of monthname oddity.
(mapconcat 'eval calendar-date-display-form ""))))
;;;###cal-autoload
(defun calendar-bahai-print-date ()
"Show the Bahá'í calendar equivalent of the selected date."
(interactive)
(message "Bahá'í date: %s"
(calendar-bahai-date-string (calendar-cursor-to-date t))))
(let ((s (calendar-bahai-date-string (calendar-cursor-to-date t))))
(if (string-equal s "")
(message "Date is pre-Bahá'í")
(message "Bahá'í date: %s" s))))
(define-obsolete-function-alias
'calendar-print-bahai-date 'calendar-bahai-print-date "23.1")
......
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