1 ;;; time-date.el --- Date and time handling functions
2 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2005 Free Software Foundation, Inc.
4 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
5 ;; Masanobu Umeda <umerin@mse.kyutech.ac.jp>
6 ;; Keywords: mail news util
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 ;; Boston, MA 02111-1307, USA.
27 ;; Time values come in three formats. The oldest format is a cons
28 ;; cell of the form (HIGH . LOW). This format is obsolete, but still
29 ;; supported. The two other formats are the lists (HIGH LOW) and
30 ;; (HIGH LOW MICRO). The first two formats specify HIGH * 2^16 + LOW
31 ;; seconds; the third format specifies HIGH * 2^16 + LOW + MICRO /
32 ;; 1000000 seconds. We should have 0 <= MICRO < 1000000 and 0 <= LOW
33 ;; < 2^16. If the time value represents a point in time, then HIGH is
34 ;; nonnegative. If the time value is a time difference, then HIGH can
35 ;; be negative as well. The macro `with-decoded-time-value' and the
36 ;; function `encode-time-value' make it easier to deal with these
37 ;; three formats. See `time-subtract' for an example of how to use
42 (eval-when-compile (require 'cl))
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 3 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 3 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 'timezone-make-date-arpa-standard "timezone")
98 (defun date-to-time (date)
99 "Parse a string that represents a date-time and return a time value."
103 ;; `parse-time-string' isn't sufficiently general or
104 ;; robust. It fails to grok some of the formats that
105 ;; timezone does (e.g. dodgy post-2000 stuff from some
106 ;; Elms) and either fails or returns bogus values. Lars
107 ;; reverted this change, but that loses non-trivially
108 ;; often for me. -- fx
109 (timezone-make-date-arpa-standard date)))
110 (error (error "Invalid date: %s" date))))
112 (defun time-to-seconds (time)
113 "Convert time value TIME to a floating point number.
114 You can use `float-time' instead."
115 (with-decoded-time-value ((high low micro time))
116 (+ (* 1.0 high #x10000)
118 (/ micro 1000000.0))))
121 (defun seconds-to-time (seconds)
122 "Convert SECONDS (a floating point number) to a time value."
123 (list (floor seconds #x10000)
124 (floor (mod seconds #x10000))
125 (floor (* (- seconds (ffloor seconds)) 1000000))))
128 (defun time-less-p (t1 t2)
129 "Say whether time value T1 is less than time value T2."
130 (with-decoded-time-value ((high1 low1 micro1 t1)
131 (high2 low2 micro2 t2))
136 (< micro1 micro2)))))))
139 (defun days-to-time (days)
140 "Convert DAYS into a time value."
141 (let* ((seconds (* 1.0 days 60 60 24))
142 (high (condition-case nil (floor (/ seconds #x10000))
143 (range-error most-positive-fixnum))))
144 (list high (condition-case nil (floor (- seconds (* 1.0 high #x10000)))
145 (range-error #xffff)))))
148 (defun time-since (time)
149 "Return the time elapsed since TIME.
150 TIME should be either a time value or a date-time string."
152 ;; Convert date strings to internal time.
153 (setq time (date-to-time time)))
154 (time-subtract (current-time) time))
157 (defalias 'subtract-time 'time-subtract)
160 (defun time-subtract (t1 t2)
161 "Subtract two time values.
162 Return the difference in the format of a time value."
163 (with-decoded-time-value ((high low micro type t1)
164 (high2 low2 micro2 type2 t2))
165 (setq high (- high high2)
167 micro (- micro micro2)
168 type (max type type2))
171 micro (+ micro 1000000)))
174 low (+ low #x10000)))
175 (encode-time-value high low micro type)))
178 (defun time-add (t1 t2)
179 "Add two time values. One should represent a time difference."
180 (with-decoded-time-value ((high low micro type t1)
181 (high2 low2 micro2 type2 t2))
182 (setq high (+ high high2)
184 micro (+ micro micro2)
185 type (max type type2))
186 (when (>= micro 1000000)
188 micro (- micro 1000000)))
189 (when (>= low #x10000)
191 low (- low #x10000)))
192 (encode-time-value high low micro type)))
195 (defun date-to-day (date)
196 "Return the number of days between year 1 and DATE.
197 DATE should be a date-time string."
198 (time-to-days (date-to-time date)))
201 (defun days-between (date1 date2)
202 "Return the number of days between DATE1 and DATE2.
203 DATE1 and DATE2 should be date-time strings."
204 (- (date-to-day date1) (date-to-day date2)))
207 (defun date-leap-year-p (year)
208 "Return t if YEAR is a leap year."
209 (or (and (zerop (% year 4))
210 (not (zerop (% year 100))))
211 (zerop (% year 400))))
214 (defun time-to-day-in-year (time)
215 "Return the day number within the year of the date month/day/year."
216 (let* ((tim (decode-time time))
220 (day-of-year (+ day (* 31 (1- month)))))
222 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
223 (when (date-leap-year-p year)
224 (setq day-of-year (1+ day-of-year))))
228 (defun time-to-days (time)
229 "The number of days between the Gregorian date 0001-12-31bce and TIME.
230 TIME should be a time value.
231 The Gregorian date Sunday, December 31, 1bce is imaginary."
232 (let* ((tim (decode-time time))
236 (+ (time-to-day-in-year time) ; Days this year
237 (* 365 (1- year)) ; + Days in prior years
238 (/ (1- year) 4) ; + Julian leap years
239 (- (/ (1- year) 100)) ; - century years
240 (/ (1- year) 400)))) ; + Gregorian leap years
242 (defun time-to-number-of-days (time)
243 "Return the number of days represented by TIME.
244 The number of days will be returned as a floating point number."
245 (/ (time-to-seconds time) (* 60 60 24)))
248 (defun safe-date-to-time (date)
249 "Parse a string that represents a date-time and return a time value.
250 If DATE is malformed, return a time value of zeros."
257 ;;; time-date.el ends here