("GMT-4" . -400) ("GMT-5" . -500) ("GMT-6" . -600)
("GMT-7" . -700) ("GMT-8" . -800) ("GMT-9" . -900)
("GMT-10" . -1000) ("GMT-11" . -1100) ("GMT-12" . -1200))
- "*Time differentials of timezone from GMT in hour.")
+ "*Time differentials of timezone from GMT in +-HHMM form.
+This list is obsolescent, and is present only for backwards compatibility,
+because time zone names are ambiguous in practice.
+Use `current-time-zone' instead.")
(defvar timezone-months-assoc
'(("JAN" . 1)("FEB" . 2)("MAR" . 3)
(defun timezone-make-date-arpa-standard (date &optional local timezone)
"Convert DATE to an arpanet standard date.
-Optional 1st argumetn LOCAL specifies the default local timezone of the DATE.
-Optional 2nd argument TIMEZONE specifies a timezone to be represented in."
- (let* ((date (timezone-parse-date date))
- (year (string-to-int (aref date 0)))
- (month (string-to-int (aref date 1)))
- (day (string-to-int (aref date 2)))
- (time (timezone-parse-time (aref date 3)))
- (hour (string-to-int (aref time 0)))
- (minute (string-to-int (aref time 1)))
- (second (string-to-int (aref time 2)))
- (local (or (aref date 4) local)) ;Use original if defined
- (timezone (or timezone local))
- (diff (- (timezone-zone-to-minute timezone)
- (timezone-zone-to-minute local)))
- (new (timezone-fix-time year month day
- hour (+ minute diff) second)))
+Optional 1st argument LOCAL specifies the default local timezone of the DATE;
+if nil, GMT is assumed.
+Optional 2nd argument TIMEZONE specifies a time zone to be represented in;
+if nil, the local time zone is assumed."
+ (let ((new (timezone-fix-time date local timezone)))
(timezone-make-arpa-date (aref new 0) (aref new 1) (aref new 2)
(timezone-make-time-string
(aref new 3) (aref new 4) (aref new 5))
- timezone)
+ (aref new 6))
))
(defun timezone-make-date-sortable (date &optional local timezone)
"Convert DATE to a sortable date string.
-Optional 1st argumetn LOCAL specifies the default local timezone of the DATE.
-Optional 2nd argument TIMEZONE specifies a timezone to be represented in."
- (let* ((date (timezone-parse-date date))
- (year (string-to-int (aref date 0)))
- (month (string-to-int (aref date 1)))
- (day (string-to-int (aref date 2)))
- (time (timezone-parse-time (aref date 3)))
- (hour (string-to-int (aref time 0)))
- (minute (string-to-int (aref time 1)))
- (second (string-to-int (aref time 2)))
- (local (or (aref date 4) local)) ;Use original if defined
- (timezone (or timezone local))
- (diff (- (timezone-zone-to-minute timezone)
- (timezone-zone-to-minute local)))
- (new (timezone-fix-time year month day
- hour (+ minute diff) second)))
+Optional 1st argument LOCAL specifies the default local timezone of the DATE;
+if nil, GMT is assumed.
+Optional 2nd argument TIMEZONE specifies a timezone to be represented in;
+if nil, the local time zone is assumed."
+ (let ((new (timezone-fix-time date local timezone)))
(timezone-make-sortable-date (aref new 0) (aref new 1) (aref new 2)
(timezone-make-time-string
(aref new 3) (aref new 4) (aref new 5)))
(defun timezone-make-arpa-date (year month day time &optional timezone)
"Make arpanet standard date string from YEAR, MONTH, DAY, and TIME.
Optional argument TIMEZONE specifies a time zone."
- (format "%02d %s %4d %s%s"
- day
- (capitalize (car (rassq month timezone-months-assoc)))
- ;;(- year (* (/ year 100) 100)) ;1990 -> 90
- (if (< year 100) (+ year 1900) year) ;90->1990
- time
- (if timezone (concat " " timezone) "")
- ))
+ (let ((zone
+ (if (listp timezone)
+ (let* ((m (timezone-zone-to-minute timezone))
+ (absm (if (< m 0) (- m) m)))
+ (format "%c%02d%02d"
+ (if (< m 0) ?- ?+) (/ absm 60) (% absm 60)))
+ timezone)))
+ (format "%02d %s %04d %s %s"
+ day
+ (capitalize (car (rassq month timezone-months-assoc)))
+ year
+ time
+ zone)))
(defun timezone-make-sortable-date (year month day time)
"Make sortable date string from YEAR, MONTH, DAY, and TIME."
(format "%4d%02d%02d%s"
- ;;(- year (* (/ year 100) 100)) ;1990 -> 90
- (if (< year 100) (+ year 1900) year) ;90->1990
- month day time))
+ year month day time))
(defun timezone-make-time-string (hour minute second)
"Make time string from HOUR, MINUTE, and SECOND."
;; Miscellaneous
(defun timezone-zone-to-minute (timezone)
- "Translate TIMEZONE (in zone name or integer) to integer minute."
- (if timezone
+ "Translate TIMEZONE to an integer minute offset from GMT.
+TIMEZONE can be a cons cell containing the output of current-time-zone,
+or an integer of the form +-HHMM, or a time zone name."
+ (cond
+ ((consp timezone)
+ (/ (car timezone) 60))
+ (timezone
(progn
(setq timezone
(or (cdr (assoc (upcase timezone) timezone-world-timezones))
;; by eggert@twinsun.com (Paul Eggert)
(let* ((abszone (max timezone (- timezone)))
(minutes (+ (* 60 (/ abszone 100)) (% abszone 100))))
- (if (< timezone 0) (- minutes) minutes)))
- 0))
+ (if (< timezone 0) (- minutes) minutes))))
+ (t 0)))
+
+(defun timezone-time-from-absolute (date seconds)
+ "Compute the UTC time equivalent to DATE at time SECONDS after midnight.
+Return a list suitable as an argument to current-time-zone,
+or nil if the date cannot be thus represented.
+DATE is the number of days elapsed since the (imaginary)
+Gregorian date Sunday, December 31, 1 BC."
+ (let* ((current-time-origin 719162)
+ ;; (timezone-absolute-from-gregorian 1 1 1970)
+ (days (- date current-time-origin))
+ (seconds-per-day (float 86400))
+ (seconds (+ seconds (* days seconds-per-day)))
+ (current-time-arithmetic-base (float 65536))
+ (hi (floor (/ seconds current-time-arithmetic-base)))
+ (hibase (* hi current-time-arithmetic-base))
+ (lo (floor (- seconds hibase))))
+ (and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow.
+ (cons hi lo))))
-(defun timezone-fix-time (year month day hour minute second)
- "Fix date and time."
- ;; MINUTE may be larger than 60 or smaller than -60.
- (let ((hour-fix
- (if (< minute 0)
+(defun timezone-time-zone-from-absolute (date seconds)
+ "Compute the local time zone for DATE at time SECONDS after midnight.
+Return a list in the same format as current-time-zone's result,
+or nil if the local time zone could not be computed.
+DATE is the number of days elapsed since the (imaginary)
+Gregorian date Sunday, December 31, 1 BC."
+ (and (fboundp 'current-time-zone)
+ (let ((utc-time (timezone-time-from-absolute date seconds)))
+ (and utc-time
+ (let ((zone (current-time-zone utc-time)))
+ (and (car zone) zone))))))
+
+(defun timezone-fix-time (date local timezone)
+ "Find the time represented by the string DATE (with default timezone LOCAL),
+and represent it as a YY-MM-DD-HH-MM-SS-TIMEZONE vector.
+If LOCAL is nil, it is assumed to be GMT.
+If TIMEZONE is nil, use the local time zone."
+ (let* ((date (timezone-parse-date date))
+ (year (string-to-int (aref date 0)))
+ (year (if (< year 100) (+ year 1900) year))
+ (month (string-to-int (aref date 1)))
+ (day (string-to-int (aref date 2)))
+ (time (timezone-parse-time (aref date 3)))
+ (hour (string-to-int (aref time 0)))
+ (minute (string-to-int (aref time 1)))
+ (second (string-to-int (aref time 2)))
+ (local (or (aref date 4) local)) ;Use original if defined
+ (timezone
+ (or timezone
+ (timezone-time-zone-from-absolute
+ (timezone-absolute-from-gregorian month day year)
+ (+ second (* 60 (+ minute (* 60 hour)))))))
+ (diff (- (timezone-zone-to-minute timezone)
+ (timezone-zone-to-minute local)))
+ (minute (+ minute diff))
+ (hour-fix
+ (if (< minute 0)
;;(/ (- minute 59) 60) (/ minute 60)
;; ANSI C compliance about truncation of integer division
;; by eggert@twinsun.com (Paul Eggert)
(- (/ (- 59 minute) 60)) (/ minute 60))))
(setq hour (+ hour hour-fix))
- (setq minute (- minute (* 60 hour-fix))))
- ;; HOUR may be larger than 24 or smaller than 0.
- (cond ((<= 24 hour) ;24 -> 00
- (setq hour (- hour 24))
- (setq day (1+ day))
- (if (< (timezone-last-day-of-month month year) day)
- (progn
- (setq month (1+ month))
- (setq day 1)
- (if (< 12 month)
- (progn
- (setq month 1)
- (setq year (1+ year))
- ))
- )))
- ((> 0 hour)
- (setq hour (+ hour 24))
- (setq day (1- day))
- (if (> 1 day)
- (progn
- (setq month (1- month))
- (if (> 1 month)
- (progn
- (setq month 12)
- (setq year (1- year))
- ))
- (setq day (timezone-last-day-of-month month year))
- )))
- )
- (vector year month day hour minute second))
+ (setq minute (- minute (* 60 hour-fix)))
+ ;; HOUR may be larger than 24 or smaller than 0.
+ (cond ((<= 24 hour) ;24 -> 00
+ (setq hour (- hour 24))
+ (setq day (1+ day))
+ (if (< (timezone-last-day-of-month month year) day)
+ (progn
+ (setq month (1+ month))
+ (setq day 1)
+ (if (< 12 month)
+ (progn
+ (setq month 1)
+ (setq year (1+ year))
+ ))
+ )))
+ ((> 0 hour)
+ (setq hour (+ hour 24))
+ (setq day (1- day))
+ (if (> 1 day)
+ (progn
+ (setq month (1- month))
+ (if (> 1 month)
+ (progn
+ (setq month 12)
+ (setq year (1- year))
+ ))
+ (setq day (timezone-last-day-of-month month year))
+ )))
+ )
+ (vector year month day hour minute second timezone)))
;; Partly copied from Calendar program by Edward M. Reingold.
;; Thanks a lot.
(not (zerop (% year 100))))
(zerop (% year 400))))
+(defun timezone-day-number (month day year)
+ "Return the day number within the year of the date month/day/year."
+ (let ((day-of-year (+ day (* 31 (1- month)))))
+ (if (> month 2)
+ (progn
+ (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
+ (if (timezone-leap-year-p year)
+ (setq day-of-year (1+ day-of-year)))))
+ day-of-year))
+
+(defun timezone-absolute-from-gregorian (month day year)
+ "The number of days between the Gregorian date 12/31/1 BC and month/day/year.
+The Gregorian date Sunday, December 31, 1 BC is imaginary."
+ (+ (timezone-day-number month day year);; Days this year
+ (* 365 (1- year));; + Days in prior years
+ (/ (1- year) 4);; + Julian leap years
+ (- (/ (1- year) 100));; - century years
+ (/ (1- year) 400)));; + Gregorian leap years
+
;;; timezone.el ends here
projects / emacs.git / commitdiff