1 ;;; time-date.el --- date and time handling functions
2 ;; Copyright (C) 1998, 1999, 2000 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.
31 (autoload 'timezone-make-date-arpa-standard
"timezone")
34 (defun date-to-time (date)
35 "Convert DATE into time."
39 ;; `parse-time-string' isn't sufficiently general or
40 ;; robust. It fails to grok some of the formats that
41 ;; timzeone does (e.g. dodgy post-2000 stuff from some
42 ;; Elms) and either fails or returns bogus values. Lars
43 ;; reverted this change, but that loses non-trivially
44 ;; often for me. -- fx
45 (timezone-make-date-arpa-standard date
)))
46 (error (error "Invalid date: %s" date
))))
48 (defun time-to-seconds (time)
49 "Convert TIME to a floating point number."
50 (+ (* (car time
) 65536.0)
52 (/ (or (nth 2 time
) 0) 1000000.0)))
54 (defun seconds-to-time (seconds)
55 "Convert SECONDS (a floating point number) to an Emacs time structure."
56 (list (floor seconds
65536)
57 (floor (mod seconds
65536))
58 (floor (* (- seconds
(ffloor seconds
)) 1000000))))
60 (defun time-less-p (t1 t2
)
61 "Say whether time T1 is less than time T2."
62 (or (< (car t1
) (car t2
))
63 (and (= (car t1
) (car t2
))
64 (< (nth 1 t1
) (nth 1 t2
)))))
66 (defun days-to-time (days)
67 "Convert DAYS into time."
68 (let* ((seconds (* 1.0 days
60 60 24))
70 (ms (condition-case nil
(floor (/ seconds rest
))
71 (range-error (expt 2 16)))))
72 (list ms
(condition-case nil
(round (- seconds
(* ms rest
)))
73 (range-error (expt 2 16))))))
75 (defun time-since (time)
76 "Return the time since TIME, which is either an internal time or a date."
78 ;; Convert date strings to internal time.
79 (setq time
(date-to-time time
)))
80 (let* ((current (current-time))
81 (rest (when (< (nth 1 current
) (nth 1 time
))
83 (list (- (+ (car current
) (if rest -
1 0)) (car time
))
84 (- (+ (or rest
0) (nth 1 current
)) (nth 1 time
)))))
86 (defun subtract-time (t1 t2
)
87 "Subtract two internal times."
88 (let ((borrow (< (cadr t1
) (cadr t2
))))
89 (list (- (car t1
) (car t2
) (if borrow
1 0))
90 (- (+ (if borrow
65536 0) (cadr t1
)) (cadr t2
)))))
92 (defun date-to-day (date)
93 "Return the number of days between year 1 and DATE."
94 (time-to-days (date-to-time date
)))
96 (defun days-between (date1 date2
)
97 "Return the number of days between DATE1 and DATE2."
98 (- (date-to-day date1
) (date-to-day date2
)))
100 (defun date-leap-year-p (year)
101 "Return t if YEAR is a leap year."
102 (or (and (zerop (% year
4))
103 (not (zerop (% year
100))))
104 (zerop (% year
400))))
106 (defun time-to-day-in-year (time)
107 "Return the day number within the year of the date month/day/year."
108 (let* ((tim (decode-time time
))
112 (day-of-year (+ day
(* 31 (1- month
)))))
114 (setq day-of-year
(- day-of-year
(/ (+ 23 (* 4 month
)) 10)))
115 (when (date-leap-year-p year
)
116 (setq day-of-year
(1+ day-of-year
))))
119 (defun time-to-days (time)
120 "The number of days between the Gregorian date 0001-12-31bce and TIME.
121 The Gregorian date Sunday, December 31, 1bce is imaginary."
122 (let* ((tim (decode-time time
))
126 (+ (time-to-day-in-year time
) ; Days this year
127 (* 365 (1- year
)) ; + Days in prior years
128 (/ (1- year
) 4) ; + Julian leap years
129 (- (/ (1- year
) 100)) ; - century years
130 (/ (1- year
) 400)))) ; + Gregorian leap years
133 (defun safe-date-to-time (date)
134 "Parse DATE and return a time structure.
135 If DATE is malformed, a zero time will be returned."
142 ;;; time-date.el ends here