1 ;;; time-date.el --- Date and time handling functions
3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
4 ;; 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 2, 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 This format is obsolete, but still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 (eval-when-compile (require 'cl))
46 (defmacro with-decoded-time-value (varlist &rest body)
47 "Decode a time value and bind it according to VARLIST, then eval BODY.
49 The value of the last form in BODY is returned.
51 Each element of the list VARLIST is a list of the form
52 \(HIGH-SYMBOL LOW-SYMBOL MICRO-SYMBOL [TYPE-SYMBOL] TIME-VALUE).
53 The time value TIME-VALUE is decoded and the result it bound to
54 the symbols HIGH-SYMBOL, LOW-SYMBOL and MICRO-SYMBOL.
56 The optional TYPE-SYMBOL is bound to the type of the time value.
57 Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH
58 LOW), and type 3 is the list (HIGH LOW MICRO)."
60 (debug ((&rest (symbolp symbolp symbolp &or [symbolp form] form))
63 (let* ((elt (pop varlist))
67 (type (unless (eq (length elt) 1)
69 (time-value (car elt))
70 (gensym (make-symbol "time")))
71 `(let* ,(append `((,gensym ,time-value)
77 (setq ,low (pop ,gensym))
79 ,(append `(setq ,micro (car ,gensym))
80 (when type `(,type 2)))
81 ,(append `(setq ,micro 0)
82 (when type `(,type 1)))))
83 ,(append `(setq ,low ,gensym ,micro 0)
84 (when type `(,type 0))))
85 (with-decoded-time-value ,varlist ,@body)))
88 (defun encode-time-value (high low micro type)
89 "Encode HIGH, LOW, and MICRO into a time value of type TYPE.
90 Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH LOW),
91 and type 3 is the list (HIGH LOW MICRO)."
93 ((eq type 0) (cons high low))
94 ((eq type 1) (list high low))
95 ((eq type 2) (list high low micro))))
97 (autoload 'parse-time-string "parse-time")
98 (autoload 'timezone-make-date-arpa-standard "timezone")
101 (defun date-to-time (date)
102 "Parse a string that represents a date-time and return a time value."
106 ;; `parse-time-string' isn't sufficiently general or
107 ;; robust. It fails to grok some of the formats that
108 ;; timezone does (e.g. dodgy post-2000 stuff from some
109 ;; Elms) and either fails or returns bogus values. Lars
110 ;; reverted this change, but that loses non-trivially
111 ;; often for me. -- fx
112 (timezone-make-date-arpa-standard date)))
113 (error (error "Invalid date: %s" date))))
115 (defun time-to-seconds (time)
116 "Convert time value TIME to a floating point number.
117 You can use `float-time' instead."
118 (with-decoded-time-value ((high low micro time))
119 (+ (* 1.0 high 65536)
121 (/ micro 1000000.0))))
124 (defun seconds-to-time (seconds)
125 "Convert SECONDS (a floating point number) to a time value."
126 (list (floor seconds 65536)
127 (floor (mod seconds 65536))
128 (floor (* (- seconds (ffloor seconds)) 1000000))))
131 (defun time-less-p (t1 t2)
132 "Say whether time value T1 is less than time value T2."
133 (with-decoded-time-value ((high1 low1 micro1 t1)
134 (high2 low2 micro2 t2))
139 (< micro1 micro2)))))))
142 (defun days-to-time (days)
143 "Convert DAYS into a time value."
144 (let* ((seconds (* 1.0 days 60 60 24))
145 (high (condition-case nil (floor (/ seconds 65536))
146 (range-error most-positive-fixnum))))
147 (list high (condition-case nil (floor (- seconds (* 1.0 high 65536)))
148 (range-error 65535)))))
151 (defun time-since (time)
152 "Return the time elapsed since TIME.
153 TIME should be either a time value or a date-time string."
155 ;; Convert date strings to internal time.
156 (setq time (date-to-time time)))
157 (time-subtract (current-time) time))
160 (defalias 'subtract-time 'time-subtract)
163 (defun time-subtract (t1 t2)
164 "Subtract two time values.
165 Return the difference in the format of a time value."
166 (with-decoded-time-value ((high low micro type t1)
167 (high2 low2 micro2 type2 t2))
168 (setq high (- high high2)
170 micro (- micro micro2)
171 type (max type type2))
174 micro (+ micro 1000000)))
178 (encode-time-value high low micro type)))
181 (defun time-add (t1 t2)
182 "Add two time values. One should represent a time difference."
183 (with-decoded-time-value ((high low micro type t1)
184 (high2 low2 micro2 type2 t2))
185 (setq high (+ high high2)
187 micro (+ micro micro2)
188 type (max type type2))
189 (when (>= micro 1000000)
191 micro (- micro 1000000)))
195 (encode-time-value high low micro type)))
198 (defun date-to-day (date)
199 "Return the number of days between year 1 and DATE.
200 DATE should be a date-time string."
201 (time-to-days (date-to-time date)))
204 (defun days-between (date1 date2)
205 "Return the number of days between DATE1 and DATE2.
206 DATE1 and DATE2 should be date-time strings."
207 (- (date-to-day date1) (date-to-day date2)))
210 (defun date-leap-year-p (year)
211 "Return t if YEAR is a leap year."
212 (or (and (zerop (% year 4))
213 (not (zerop (% year 100))))
214 (zerop (% year 400))))
217 (defun time-to-day-in-year (time)
218 "Return the day number within the year of the date month/day/year."
219 (let* ((tim (decode-time time))
223 (day-of-year (+ day (* 31 (1- month)))))
225 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
226 (when (date-leap-year-p year)
227 (setq day-of-year (1+ day-of-year))))
231 (defun time-to-days (time)
232 "The number of days between the Gregorian date 0001-12-31bce and TIME.
233 TIME should be a time value.
234 The Gregorian date Sunday, December 31, 1bce is imaginary."
235 (let* ((tim (decode-time time))
239 (+ (time-to-day-in-year time) ; Days this year
240 (* 365 (1- year)) ; + Days in prior years
241 (/ (1- year) 4) ; + Julian leap years
242 (- (/ (1- year) 100)) ; - century years
243 (/ (1- year) 400)))) ; + Gregorian leap years
245 (defun time-to-number-of-days (time)
246 "Return the number of days represented by TIME.
247 The number of days will be returned as a floating point number."
248 (/ (time-to-seconds time) (* 60 60 24)))
251 (defun safe-date-to-time (date)
252 "Parse a string that represents a date-time and return a time value.
253 If DATE is malformed, return a time value of zeros."
260 ;;; time-date.el ends here