;;; cal-dst.el --- calendar functions for daylight savings rules.
-;; Copyright (C) 1993 Free Software Foundation, Inc.
+;; Copyright (C) 1993, 1994, 1995, 1996 Free Software Foundation, Inc.
;; Author: Paul Eggert <eggert@twinsun.com>
;; Edward M. Reingold <reingold@cs.uiuc.edu>
;; 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. No author or distributor
-;; accepts responsibility to anyone for the consequences of using it
-;; or for whether it serves any particular purpose or works at all,
-;; unless he says so in writing. Refer to the GNU Emacs General Public
-;; License for full details.
-
-;; Everyone is granted permission to copy, modify and redistribute
-;; GNU Emacs, but only under the conditions described in the
-;; GNU Emacs General Public License. A copy of this license is
-;; supposed to have been given to you along with GNU Emacs so you
-;; can know your rights and responsibilities. It should be in a
-;; file named COPYING. Among other things, the copyright notice
-;; and this notice must be preserved on all copies.
+;; 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, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
;;; Commentary:
;;; Code:
(require 'calendar)
+(require 'cal-persia)
(defvar calendar-current-time-zone-cache nil
"Cache for result of calendar-current-time-zone.")
(defun calendar-time-zone-daylight-rules (abs-date utc-diff)
"Return daylight transition rule for ABS-DATE, UTC-DIFF sec offset from UTC.
-ABS-DIFF must specify a day that contains a daylight savings transition.
+ABS-DATE must specify a day that contains a daylight savings transition.
The result has the proper form for calendar-daylight-savings-starts'."
(let* ((date (calendar-gregorian-from-absolute abs-date))
(weekday (% abs-date 7))
(cons
(list 'calendar-nth-named-day 1 weekday m 'year j)
l)))
- l)))
+ l)
+ ;; 01-01 and 07-01 for this year's Persian calendar.
+ (if (and (= m 3) (<= 20 d) (<= d 21))
+ '((calendar-gregorian-from-absolute
+ (calendar-absolute-from-persian
+ (list 1 1 (- year 621))))))
+ (if (and (= m 9) (<= 22 d) (<= d 23))
+ '((calendar-gregorian-from-absolute
+ (calendar-absolute-from-persian
+ (list 7 1 (- year 621))))))))
(prevday-sec (- -1 utc-diff)) ;; last sec of previous local day
(year (1+ y)))
;; Scan through the next few years until only one rule remains.
(cons
(/ (abs (- t0-utc-diff t1-utc-diff)) 60)
(if (< t0-utc-diff t1-utc-diff)
- (list t0-name t1-name t1-rules t2-rules t2-time t1-time)
- (list t1-name t0-name t2-rules t1-rules t1-time t2-time)
+ (list t0-name t1-name t1-rules t2-rules t1-time t2-time)
+ (list t1-name t0-name t2-rules t1-rules t2-time t1-time)
)))))))))))
-;;; The following six defvars relating to daylight savings time should NOT be
+;;; The following eight defvars relating to daylight savings time should NOT be
;;; marked to go into loaddefs.el where they would be evaluated when Emacs is
;;; dumped. These variables' appropriate values depend on the conditions under
;;; which the code is INVOKED; so it's inappropriate to initialize them when
If the locale never uses daylight savings time, set this to nil.")
;;;###autoload
-(put 'calendar-daylight-savings-starts 'risky-local-variable t)
+(put 'calendar-daylight-savings-ends 'risky-local-variable t)
(defvar calendar-daylight-savings-ends
(or (car (nthcdr 5 calendar-current-time-zone-cache))
(and (not (zerop calendar-daylight-time-offset))
calendar-daylight-savings-starts-time)
"*Number of minutes after midnight that daylight savings time ends.")
+(defun dst-in-effect (date)
+ "True if on absolute DATE daylight savings time is in effect.
+Fractional part of DATE is local standard time of day."
+ (let* ((year (extract-calendar-year
+ (calendar-gregorian-from-absolute (floor date))))
+ (dst-starts-gregorian (eval calendar-daylight-savings-starts))
+ (dst-ends-gregorian (eval calendar-daylight-savings-ends))
+ (dst-starts (and dst-starts-gregorian
+ (+ (calendar-absolute-from-gregorian
+ dst-starts-gregorian)
+ (/ calendar-daylight-savings-starts-time
+ 60.0 24.0))))
+ (dst-ends (and dst-ends-gregorian
+ (+ (calendar-absolute-from-gregorian
+ dst-ends-gregorian)
+ (/ (- calendar-daylight-savings-ends-time
+ calendar-daylight-time-offset)
+ 60.0 24.0)))))
+ (and dst-starts dst-ends
+ (if (< dst-starts dst-ends)
+ (and (<= dst-starts date) (< date dst-ends))
+ (or (<= dst-starts date) (< date dst-ends))))))
+
+(defun dst-adjust-time (date time &optional style)
+ "Adjust, to account for dst on DATE, decimal fraction standard TIME.
+Returns a list (date adj-time zone) where `date' and `adj-time' are the values
+adjusted for `zone'; here `date' is a list (month day year), `adj-time' is a
+decimal fraction time, and `zone' is a string.
+
+Optional parameter STYLE forces the result time to be standard time when its
+value is 'standard and daylight savings time (if available) when its value is
+'daylight.
+
+Conversion to daylight savings time is done according to
+`calendar-daylight-savings-starts', `calendar-daylight-savings-ends',
+`calendar-daylight-savings-starts-time',
+`calendar-daylight-savings-ends-time', and
+`calendar-daylight-savings-offset'."
+
+ (let* ((rounded-abs-date (+ (calendar-absolute-from-gregorian date)
+ (/ (round (* 60 time)) 60.0 24.0)))
+ (dst (dst-in-effect rounded-abs-date))
+ (time-zone (if dst
+ calendar-daylight-time-zone-name
+ calendar-standard-time-zone-name))
+ (time (+ rounded-abs-date
+ (if dst (/ calendar-daylight-time-offset 24.0 60.0) 0))))
+ (list (calendar-gregorian-from-absolute (truncate time))
+ (* 24.0 (- time (truncate time)))
+ time-zone)))
+
(provide 'cal-dst)
;;; cal-dst.el ends here