1 ;;; time-date.el --- Date and time handling functions
3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
4 ;; 2007, 2008 Free Software Foundation, Inc.
6 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; Masanobu Umeda <umerin@mse.kyutech.ac.jp>
8 ;; Keywords: mail news util
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software; you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation; either version 3, or (at your option)
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25 ;; Boston, MA 02110-1301, USA.
29 ;; Time values come in three formats. The oldest format is a cons
30 ;; cell of the form (HIGH . LOW). This format is obsolete, but still
31 ;; supported. The two other formats are the lists (HIGH LOW) and
32 ;; (HIGH LOW MICRO). The first two formats specify HIGH * 2^16 + LOW
33 ;; seconds; the third format specifies HIGH * 2^16 + LOW + MICRO /
34 ;; 1000000 seconds. We should have 0 <= MICRO < 1000000 and 0 <= LOW
35 ;; < 2^16. If the time value represents a point in time, then HIGH is
36 ;; nonnegative. If the time value is a time difference, then HIGH can
37 ;; be negative as well. The macro `with-decoded-time-value' and the
38 ;; function `encode-time-value' make it easier to deal with these
39 ;; three formats. See `time-subtract' for an example of how to use
44 (defmacro with-decoded-time-value (varlist &rest body)
45 "Decode a time value and bind it according to VARLIST, then eval BODY.
47 The value of the last form in BODY is returned.
49 Each element of the list VARLIST is a list of the form
50 \(HIGH-SYMBOL LOW-SYMBOL MICRO-SYMBOL [TYPE-SYMBOL] TIME-VALUE).
51 The time value TIME-VALUE is decoded and the result it bound to
52 the symbols HIGH-SYMBOL, LOW-SYMBOL and MICRO-SYMBOL.
54 The optional TYPE-SYMBOL is bound to the type of the time value.
55 Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH
56 LOW), and type 2 is the list (HIGH LOW MICRO)."
58 (debug ((&rest (symbolp symbolp symbolp &or [symbolp form] form))
61 (let* ((elt (pop varlist))
65 (type (unless (eq (length elt) 1)
67 (time-value (car elt))
68 (gensym (make-symbol "time")))
69 `(let* ,(append `((,gensym ,time-value)
75 (setq ,low (pop ,gensym))
77 ,(append `(setq ,micro (car ,gensym))
78 (when type `(,type 2)))
79 ,(append `(setq ,micro 0)
80 (when type `(,type 1)))))
81 ,(append `(setq ,low ,gensym ,micro 0)
82 (when type `(,type 0))))
83 (with-decoded-time-value ,varlist ,@body)))
86 (defun encode-time-value (high low micro type)
87 "Encode HIGH, LOW, and MICRO into a time value of type TYPE.
88 Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH LOW),
89 and type 2 is the list (HIGH LOW MICRO)."
91 ((eq type 0) (cons high low))
92 ((eq type 1) (list high low))
93 ((eq type 2) (list high low micro))))
95 (autoload 'parse-time-string "parse-time")
96 (autoload 'timezone-make-date-arpa-standard "timezone")
99 (defun date-to-time (date)
100 "Parse a string that represents a date-time and return a time value."
104 ;; `parse-time-string' isn't sufficiently general or
105 ;; robust. It fails to grok some of the formats that
106 ;; timezone does (e.g. dodgy post-2000 stuff from some
107 ;; Elms) and either fails or returns bogus values. Lars
108 ;; reverted this change, but that loses non-trivially
109 ;; often for me. -- fx
110 (timezone-make-date-arpa-standard date)))
111 (error (error "Invalid date: %s" date))))
114 (defun time-to-seconds (time)
115 "Convert time value TIME to a floating point number.
116 You can use `float-time' instead."
117 (with-decoded-time-value ((high low micro time))
118 (+ (* 1.0 high 65536)
120 (/ micro 1000000.0))))
123 (defun seconds-to-time (seconds)
124 "Convert SECONDS (a floating point number) to a time value."
125 (list (floor seconds 65536)
126 (floor (mod seconds 65536))
127 (floor (* (- seconds (ffloor seconds)) 1000000))))
130 (defun time-less-p (t1 t2)
131 "Say whether time value T1 is less than time value T2."
132 (with-decoded-time-value ((high1 low1 micro1 t1)
133 (high2 low2 micro2 t2))
138 (< micro1 micro2)))))))
141 (defun days-to-time (days)
142 "Convert DAYS into a time value."
143 (let* ((seconds (* 1.0 days 60 60 24))
144 (high (condition-case nil (floor (/ seconds 65536))
145 (range-error most-positive-fixnum))))
146 (list high (condition-case nil (floor (- seconds (* 1.0 high 65536)))
147 (range-error 65535)))))
150 (defun time-since (time)
151 "Return the time elapsed since TIME.
152 TIME should be either a time value or a date-time string."
154 ;; Convert date strings to internal time.
155 (setq time (date-to-time time)))
156 (time-subtract (current-time) time))
159 (defalias 'subtract-time 'time-subtract)
162 (defun time-subtract (t1 t2)
163 "Subtract two time values.
164 Return the difference in the format of a time value."
165 (with-decoded-time-value ((high low micro type t1)
166 (high2 low2 micro2 type2 t2))
167 (setq high (- high high2)
169 micro (- micro micro2)
170 type (max type type2))
173 micro (+ micro 1000000)))
177 (encode-time-value high low micro type)))
180 (defun time-add (t1 t2)
181 "Add two time values. One should represent a time difference."
182 (with-decoded-time-value ((high low micro type t1)
183 (high2 low2 micro2 type2 t2))
184 (setq high (+ high high2)
186 micro (+ micro micro2)
187 type (max type type2))
188 (when (>= micro 1000000)
190 micro (- micro 1000000)))
194 (encode-time-value high low micro type)))
197 (defun date-to-day (date)
198 "Return the number of days between year 1 and DATE.
199 DATE should be a date-time string."
200 (time-to-days (date-to-time date)))
203 (defun days-between (date1 date2)
204 "Return the number of days between DATE1 and DATE2.
205 DATE1 and DATE2 should be date-time strings."
206 (- (date-to-day date1) (date-to-day date2)))
209 (defun date-leap-year-p (year)
210 "Return t if YEAR is a leap year."
211 (or (and (zerop (% year 4))
212 (not (zerop (% year 100))))
213 (zerop (% year 400))))
216 (defun time-to-day-in-year (time)
217 "Return the day number within the year corresponding to TIME."
218 (let* ((tim (decode-time time))
222 (day-of-year (+ day (* 31 (1- month)))))
224 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
225 (when (date-leap-year-p year)
226 (setq day-of-year (1+ day-of-year))))
230 (defun time-to-days (time)
231 "The number of days between the Gregorian date 0001-12-31bce and TIME.
232 TIME should be a time value.
233 The Gregorian date Sunday, December 31, 1bce is imaginary."
234 (let* ((tim (decode-time time))
238 (+ (time-to-day-in-year time) ; Days this year
239 (* 365 (1- year)) ; + Days in prior years
240 (/ (1- year) 4) ; + Julian leap years
241 (- (/ (1- year) 100)) ; - century years
242 (/ (1- year) 400)))) ; + Gregorian leap years
244 (defun time-to-number-of-days (time)
245 "Return the number of days represented by TIME.
246 The number of days will be returned as a floating point number."
247 (/ (time-to-seconds time) (* 60 60 24)))
250 (defun safe-date-to-time (date)
251 "Parse a string that represents a date-time and return a time value.
252 If DATE is malformed, return a time value of zeros."
259 (defun format-seconds (string seconds)
260 "Use format control STRING to format the number SECONDS.
261 The valid format specifiers are:
262 %y is the number of (365-day) years.
263 %d is the number of days.
264 %h is the number of hours.
265 %m is the number of minutes.
266 %s is the number of seconds.
267 %z is a non-printing control flag (see below).
268 %% is a literal \"%\".
270 Upper-case specifiers are followed by the unit-name (e.g. \"years\").
271 Lower-case specifiers return only the unit.
273 \"%\" may be followed by a number specifying a width, with an
274 optional leading \".\" for zero-padding. For example, \"%.3Y\" will
275 return something of the form \"001 year\".
277 The \"%z\" specifier does not print anything. When it is used, specifiers
278 must be given in order of decreasing size. To the left of \"%z\", nothing
279 is output until the first non-zero unit is encountered.
281 This function does not work for SECONDS greater than `most-positive-fixnum'."
283 (units '(("y" "year" 31536000)
290 spec match usedunits zeroflag larger prev name unit num zeropos)
291 (while (string-match "%\\.?[0-9]*\\(.\\)" string start)
292 (setq start (match-end 0)
293 spec (match-string 1 string))
294 (unless (string-equal spec "%")
295 (or (setq match (assoc-string spec units t))
296 (error "Bad format specifier: `%s'" spec))
297 (if (assoc-string spec usedunits t)
298 (error "Multiple instances of specifier: `%s'" spec))
299 (if (string-equal (car match) "z")
302 (setq unit (nth 2 match)
303 larger (and prev (> unit prev))
305 (push match usedunits)))
307 (error "Units are not in decreasing order of size"))
312 (when (string-match (format "%%\\(\\.?[0-9]+\\)?\\(%s\\)" spec) string)
313 (if (string-equal spec "z") ; must be last in units
315 (replace-regexp-in-string
317 (substring string (min (or zeropos (match-end 0))
318 (match-beginning 0)))))
319 ;; Cf article-make-date-line in gnus-art.
320 (setq num (floor seconds unit)
321 seconds (- seconds (* num unit)))
322 ;; Start position of the first non-zero unit.
324 (setq zeropos (unless (zerop num) (match-beginning 0))))
327 (format (concat "%" (match-string 1 string) "d%s") num
328 (if (string-equal (match-string 2 string) spec)
329 "" ; lower-case, no unit-name
331 (if (= num 1) "" "s"))))
333 (replace-regexp-in-string "%%" "%" string))
338 ;;; arch-tag: addcf07b-b20a-465b-af72-550b8ac5190f
339 ;;; time-date.el ends here