*** empty log message ***

1 files changed, 142 insertions, 84 deletions

diff --git a/lisp/timezone.el b/lisp/timezone.el
index c2f932b16dd..8f3335d17d9 100644
--- a/lisp/timezone.el
+++ b/lisp/timezone.el
@@ -49,7 +49,10 @@
     ("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)
@@ -60,46 +63,24 @@
 
 (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)))
@@ -113,21 +94,24 @@ Optional 2nd argument TIMEZONE specifies a timezone to be represented in."
 (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."
@@ -233,8 +217,13 @@ Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
 ;; 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))
@@ -249,49 +238,99 @@ Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
 	;; 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.
@@ -308,4 +347,23 @@ Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
 	   (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