lisp/timezone.el

   1 ;;; timezone.el --- time zone package for GNU Emacs
   2
   3 ;; Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Masanobu Umeda
   6 ;; Maintainer: umerin@mse.kyutech.ac.jp
   7 ;; Keywords: news
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Code:
  27
  28 (provide 'timezone)
  29
  30 (defvar timezone-world-timezones
  31   '(("PST" .  -800)
  32     ("PDT" .  -700)
  33     ("MST" .  -700)
  34     ("MDT" .  -600)
  35     ("CST" .  -600)
  36     ("CDT" .  -500)
  37     ("EST" .  -500)
  38     ("EDT" .  -400)
  39     ("AST" .  -400)                     ;by <clamen@CS.CMU.EDU>
  40     ("NST" .  -330)                     ;by <clamen@CS.CMU.EDU>
  41     ("UT"  .  +000)
  42     ("GMT" .  +000)
  43     ("BST" .  +100)
  44     ("MET" .  +100)
  45     ("EET" .  +200)
  46     ("JST" .  +900)
  47     ("GMT+1"  .  +100) ("GMT+2"  .  +200) ("GMT+3"  .  +300)
  48     ("GMT+4"  .  +400) ("GMT+5"  .  +500) ("GMT+6"  .  +600)
  49     ("GMT+7"  .  +700) ("GMT+8"  .  +800) ("GMT+9"  .  +900)
  50     ("GMT+10" . +1000) ("GMT+11" . +1100) ("GMT+12" . +1200) ("GMT+13" . +1300)
  51     ("GMT-1"  .  -100) ("GMT-2"  .  -200) ("GMT-3"  .  -300)
  52     ("GMT-4"  .  -400) ("GMT-5"  .  -500) ("GMT-6"  .  -600)
  53     ("GMT-7"  .  -700) ("GMT-8"  .  -800) ("GMT-9"  .  -900)
  54     ("GMT-10" . -1000) ("GMT-11" . -1100) ("GMT-12" . -1200))
  55   "*Time differentials of timezone from GMT in +-HHMM form.
  56 This list is obsolescent, and is present only for backwards compatibility,
  57 because time zone names are ambiguous in practice.
  58 Use `current-time-zone' instead.")
  59
  60 (defvar timezone-months-assoc
  61   '(("JAN" .  1)("FEB" .  2)("MAR" .  3)
  62     ("APR" .  4)("MAY" .  5)("JUN" .  6)
  63     ("JUL" .  7)("AUG" .  8)("SEP" .  9)
  64     ("OCT" . 10)("NOV" . 11)("DEC" . 12))
  65   "Alist of first three letters of a month and its numerical representation.")
  66
  67 (defun timezone-make-date-arpa-standard (date &optional local timezone)
  68   "Convert DATE to an arpanet standard date.
  69 Optional 1st argument LOCAL specifies the default local timezone of the DATE;
  70 if nil, GMT is assumed.
  71 Optional 2nd argument TIMEZONE specifies a time zone to be represented in;
  72 if nil, the local time zone is assumed."
  73   (let ((new (timezone-fix-time date local timezone)))
  74     (timezone-make-arpa-date (aref new 0) (aref new 1) (aref new 2)
  75                              (timezone-make-time-string
  76                               (aref new 3) (aref new 4) (aref new 5))
  77                              (aref new 6))
  78     ))
  79
  80 (defun timezone-make-date-sortable (date &optional local timezone)
  81   "Convert DATE to a sortable date string.
  82 Optional 1st argument LOCAL specifies the default local timezone of the DATE;
  83 if nil, GMT is assumed.
  84 Optional 2nd argument TIMEZONE specifies a timezone to be represented in;
  85 if nil, the local time zone is assumed."
  86   (let ((new (timezone-fix-time date local timezone)))
  87     (timezone-make-sortable-date (aref new 0) (aref new 1) (aref new 2)
  88                                  (timezone-make-time-string
  89                                   (aref new 3) (aref new 4) (aref new 5)))
  90     ))
  91
  92 \f
  93 ;;
  94 ;; Parsers and Constructors of Date and Time
  95 ;;
  96
  97 (defun timezone-make-arpa-date (year month day time &optional timezone)
  98   "Make arpanet standard date string from YEAR, MONTH, DAY, and TIME.
  99 Optional argument TIMEZONE specifies a time zone."
 100   (let ((zone
 101          (if (listp timezone)
 102              (let* ((m (timezone-zone-to-minute timezone))
 103                     (absm (if (< m 0) (- m) m)))
 104                (format "%c%02d%02d"
 105                        (if (< m 0) ?- ?+) (/ absm 60) (% absm 60)))
 106            timezone)))
 107     (format "%02d %s %04d %s %s"
 108             day
 109             (capitalize (car (rassq month timezone-months-assoc)))
 110             year
 111             time
 112             zone)))
 113
 114 (defun timezone-make-sortable-date (year month day time)
 115   "Make sortable date string from YEAR, MONTH, DAY, and TIME."
 116   (format "%4d%02d%02d%s"
 117           year month day time))
 118
 119 (defun timezone-make-time-string (hour minute second)
 120   "Make time string from HOUR, MINUTE, and SECOND."
 121   (format "%02d:%02d:%02d" hour minute second))
 122
 123 (defun timezone-parse-date (date)
 124   "Parse DATE and return a vector [YEAR MONTH DAY TIME TIMEZONE].
 125 19 is prepended to year if necessary.  Timezone may be nil if nothing.
 126 Understands the following styles:
 127  (1) 14 Apr 89 03:20[:12] [GMT]
 128  (2) Fri, 17 Mar 89 4:01[:33] [GMT]
 129  (3) Mon Jan 16 16:12[:37] [GMT] 1989
 130  (4) 6 May 1992 1641-JST (Wednesday)
 131  (5) 22-AUG-1993 10:59:12.82
 132  (6) Thu, 11 Apr 16:17:12 91 [MET]
 133  (7) Mon, 6  Jul 16:47:20 T 1992 [MET]"
 134   ;; Get rid of any text properties.
 135   (and (stringp date)
 136        (or (text-properties-at 0 date)
 137            (next-property-change 0 date))
 138        (setq date (copy-sequence date))
 139        (set-text-properties 0 (length date) nil date))
 140   (let ((date (or date ""))
 141         (year nil)
 142         (month nil)
 143         (day nil)
 144         (time nil)
 145         (zone nil))                     ;This may be nil.
 146     (cond ((string-match
 147             "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\'" date)
 148            ;; Styles: (6) and (7) without timezone
 149            (setq year 6 month 3 day 2 time 4 zone nil))
 150           ((string-match
 151             "\\([^ \t,]+\\),[ \t]+\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\(T[ \t]+\\|\\)\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
 152            ;; Styles: (6) and (7) with timezone and buggy timezone
 153            (setq year 6 month 3 day 2 time 4 zone 7))
 154           ((string-match
 155             "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\'" date)
 156            ;; Styles: (1) and (2) without timezone
 157            (setq year 3 month 2 day 1 time 4 zone nil))
 158           ((string-match
 159             "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
 160            ;; Styles: (1) and (2) with timezone and buggy timezone
 161            (setq year 3 month 2 day 1 time 4 zone 5))
 162           ((string-match
 163             "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([0-9]+\\)" date)
 164            ;; Styles: (3) without timezone
 165            (setq year 4 month 1 day 2 time 3 zone nil))
 166           ((string-match
 167             "\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9:]+\\)[ \t]+\\([-+a-zA-Z0-9]+\\)[ \t]+\\([0-9]+\\)" date)
 168            ;; Styles: (3) with timezone
 169            (setq year 5 month 1 day 2 time 3 zone 4))
 170           ((string-match
 171             "\\([0-9]+\\)[ \t]+\\([^ \t,]+\\)[ \t]+\\([0-9]+\\)[ \t]+\\([0-9]+\\)[ \t]*\\([-+a-zA-Z0-9]+\\)" date)
 172            ;; Styles: (4) with timezone
 173            (setq year 3 month 2 day 1 time 4 zone 5))
 174           ((string-match
 175             "\\([0-9]+\\)-\\([A-Za-z]+\\)-\\([0-9]+\\)[ \t]+\\([0-9]+:[0-9]+:[0-9]+\\)\\.[0-9]+" date)
 176            ;; Styles: (5) without timezone.
 177            (setq year 3 month 2 day 1 time 4 zone nil))
 178           )
 179     (if year
 180         (progn
 181           (setq year
 182                 (substring date (match-beginning year) (match-end year)))
 183           ;; It is now Dec 1992.  8 years before the end of the World.
 184           (if (< (length year) 4)
 185               (setq year (concat "19" (substring year -2 nil))))
 186           (let ((string (substring date
 187                                    (match-beginning month)
 188                                    (+ (match-beginning month) 3))))
 189             (setq month
 190                   (int-to-string
 191                    (cdr (assoc (upcase string) timezone-months-assoc)))))
 192
 193           (setq day
 194                 (substring date (match-beginning day) (match-end day)))
 195           (setq time
 196                 (substring date (match-beginning time) (match-end time)))))
 197     (if zone
 198         (setq zone
 199               (substring date (match-beginning zone) (match-end zone))))
 200     ;; Return a vector.
 201     (if year
 202         (vector year month day time zone)
 203       (vector "0" "0" "0" "0" nil))
 204     ))
 205
 206 (defun timezone-parse-time (time)
 207   "Parse TIME (HH:MM:SS) and return a vector [hour minute second].
 208 Recognize HH:MM:SS, HH:MM, HHMMSS, HHMM."
 209   (let ((time (or time ""))
 210         (hour nil)
 211         (minute nil)
 212         (second nil))
 213     (cond ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)\\'" time)
 214            ;; HH:MM:SS
 215            (setq hour 1 minute 2 second 3))
 216           ((string-match "\\`\\([0-9]+\\):\\([0-9]+\\)\\'" time)
 217            ;; HH:MM
 218            (setq hour 1 minute 2 second nil))
 219           ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
 220            ;; HHMMSS
 221            (setq hour 1 minute 2 second 3))
 222           ((string-match "\\`\\([0-9][0-9]\\)\\([0-9][0-9]\\)\\'" time)
 223            ;; HHMM
 224            (setq hour 1 minute 2 second nil))
 225           )
 226     ;; Return [hour minute second]
 227     (vector
 228      (if hour
 229          (substring time (match-beginning hour) (match-end hour)) "0")
 230      (if minute
 231          (substring time (match-beginning minute) (match-end minute)) "0")
 232      (if second
 233          (substring time (match-beginning second) (match-end second)) "0"))
 234     ))
 235
 236 \f
 237 ;; Miscellaneous
 238
 239 (defun timezone-zone-to-minute (timezone)
 240   "Translate TIMEZONE to an integer minute offset from GMT.
 241 TIMEZONE can be a cons cell containing the output of current-time-zone,
 242 or an integer of the form +-HHMM, or a time zone name."
 243   (cond
 244      ((consp timezone)
 245       (/ (car timezone) 60))
 246      (timezone
 247       (progn
 248         (setq timezone
 249               (or (cdr (assoc (upcase timezone) timezone-world-timezones))
 250                   ;; +900
 251                   timezone))
 252         (if (stringp timezone)
 253             (setq timezone (string-to-int timezone)))
 254         ;; Taking account of minute in timezone.
 255         ;; HHMM -> MM
 256         (let* ((abszone (abs timezone))
 257                (minutes (+ (* 60 (/ abszone 100)) (% abszone 100))))
 258           (if (< timezone 0) (- minutes) minutes))))
 259      (t 0)))
 260
 261 (defun timezone-time-from-absolute (date seconds)
 262   "Compute the UTC time equivalent to DATE at time SECONDS after midnight.
 263 Return a list suitable as an argument to current-time-zone,
 264 or nil if the date cannot be thus represented.
 265 DATE is the number of days elapsed since the (imaginary)
 266 Gregorian date Sunday, December 31, 1 BC."
 267   (let* ((current-time-origin 719162)
 268             ;; (timezone-absolute-from-gregorian 1 1 1970)
 269          (days (- date current-time-origin))
 270          (seconds-per-day (float 86400))
 271          (seconds (+ seconds (* days seconds-per-day)))
 272          (current-time-arithmetic-base (float 65536))
 273          (hi (floor (/ seconds current-time-arithmetic-base)))
 274          (hibase (* hi current-time-arithmetic-base))
 275          (lo (floor (- seconds hibase))))
 276      (and (< (abs (- seconds (+ hibase lo))) 2) ;; Check for integer overflow.
 277           (cons hi lo))))
 278
 279 (defun timezone-time-zone-from-absolute (date seconds)
 280   "Compute the local time zone for DATE at time SECONDS after midnight.
 281 Return a list in the same format as current-time-zone's result,
 282 or nil if the local time zone could not be computed.
 283 DATE is the number of days elapsed since the (imaginary)
 284 Gregorian date Sunday, December 31, 1 BC."
 285    (and (fboundp 'current-time-zone)
 286         (let ((utc-time (timezone-time-from-absolute date seconds)))
 287           (and utc-time
 288                (let ((zone (current-time-zone utc-time)))
 289                  (and (car zone) zone))))))
 290
 291 (defun timezone-fix-time (date local timezone)
 292   "Convert DATE (default timezone LOCAL) to YYYY-MM-DD-HH-MM-SS-ZONE vector.
 293 If LOCAL is nil, it is assumed to be GMT.
 294 If TIMEZONE is nil, use the local time zone."
 295   (let* ((date   (timezone-parse-date date))
 296          (year   (string-to-int (aref date 0)))
 297          (year   (cond ((< year 50)
 298                         (+ year 2000))
 299                        ((< year 100)
 300                         (+ year 1900))
 301                        (t year)))
 302          (month  (string-to-int (aref date 1)))
 303          (day    (string-to-int (aref date 2)))
 304          (time   (timezone-parse-time (aref date 3)))
 305          (hour   (string-to-int (aref time 0)))
 306          (minute (string-to-int (aref time 1)))
 307          (second (string-to-int (aref time 2)))
 308          (local  (or (aref date 4) local)) ;Use original if defined
 309          (timezone
 310           (or timezone
 311               (timezone-time-zone-from-absolute
 312                (timezone-absolute-from-gregorian month day year)
 313                (+ second (* 60 (+ minute (* 60 hour)))))))
 314          (diff   (- (timezone-zone-to-minute timezone)
 315                     (timezone-zone-to-minute local)))
 316          (minute (+ minute diff))
 317          (hour-fix (floor minute 60)))
 318     (setq hour (+ hour hour-fix))
 319     (setq minute (- minute (* 60 hour-fix)))
 320     ;; HOUR may be larger than 24 or smaller than 0.
 321     (cond ((<= 24 hour)                 ;24 -> 00
 322            (setq hour (- hour 24))
 323            (setq day  (1+ day))
 324            (if (< (timezone-last-day-of-month month year) day)
 325                (progn
 326                  (setq month (1+ month))
 327                  (setq day 1)
 328                  (if (< 12 month)
 329                      (progn
 330                        (setq month 1)
 331                        (setq year (1+ year))
 332                        ))
 333                  )))
 334           ((> 0 hour)
 335            (setq hour (+ hour 24))
 336            (setq day  (1- day))
 337            (if (> 1 day)
 338                (progn
 339                  (setq month (1- month))
 340                  (if (> 1 month)
 341                      (progn
 342                        (setq month 12)
 343                        (setq year (1- year))
 344                        ))
 345                  (setq day (timezone-last-day-of-month month year))
 346                  )))
 347           )
 348     (vector year month day hour minute second timezone)))
 349
 350 ;; Partly copied from Calendar program by Edward M. Reingold.
 351 ;; Thanks a lot.
 352
 353 (defun timezone-last-day-of-month (month year)
 354   "The last day in MONTH during YEAR."
 355   (if (and (= month 2) (timezone-leap-year-p year))
 356       29
 357     (aref [31 28 31 30 31 30 31 31 30 31 30 31] (1- month))))
 358
 359 (defun timezone-leap-year-p (year)
 360   "Returns t if YEAR is a Gregorian leap year."
 361   (or (and (zerop  (% year 4))
 362            (not (zerop (% year 100))))
 363       (zerop (% year 400))))
 364
 365 (defun timezone-day-number (month day year)
 366   "Return the day number within the year of the date month/day/year."
 367   (let ((day-of-year (+ day (* 31 (1- month)))))
 368     (if (> month 2)
 369         (progn
 370           (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
 371           (if (timezone-leap-year-p year)
 372               (setq day-of-year (1+ day-of-year)))))
 373     day-of-year))
 374
 375 (defun timezone-absolute-from-gregorian (month day year)
 376   "The number of days between the Gregorian date 12/31/1 BC and month/day/year.
 377 The Gregorian date Sunday, December 31, 1 BC is imaginary."
 378   (+ (timezone-day-number month day year);; Days this year
 379      (* 365 (1- year));;        + Days in prior years
 380      (/ (1- year) 4);;          + Julian leap years
 381      (- (/ (1- year) 100));;    - century years
 382      (/ (1- year) 400)));;      + Gregorian leap years
 383
 384 ;;; timezone.el ends here