1 ;;; time-date.el --- Date and time handling functions
2 ;; Copyright (C) 1998, 1999, 2000, 2001 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.
29 (eval-when-compile (require 'cl))
33 (autoload 'timezone-make-date-arpa-standard "timezone")
36 (defun date-to-time (date)
37 "Convert DATE into time."
41 ;; `parse-time-string' isn't sufficiently general or
42 ;; robust. It fails to grok some of the formats that
43 ;; timzeone does (e.g. dodgy post-2000 stuff from some
44 ;; Elms) and either fails or returns bogus values. Lars
45 ;; reverted this change, but that loses non-trivially
46 ;; often for me. -- fx
47 (timezone-make-date-arpa-standard date)))
48 (error (error "Invalid date: %s" date))))
50 (defun time-to-seconds (time)
51 "Convert TIME to a floating point number."
52 (+ (* (car time) 65536.0)
54 (/ (or (nth 2 time) 0) 1000000.0)))
56 (defun seconds-to-time (seconds)
57 "Convert SECONDS (a floating point number) to an Emacs time structure."
58 (list (floor seconds 65536)
59 (floor (mod seconds 65536))
60 (floor (* (- seconds (ffloor seconds)) 1000000))))
62 (defun time-less-p (t1 t2)
63 "Say whether time T1 is less than time T2."
64 (or (< (car t1) (car t2))
65 (and (= (car t1) (car t2))
66 (< (nth 1 t1) (nth 1 t2)))))
68 (defun days-to-time (days)
69 "Convert DAYS into time."
70 (let* ((seconds (* 1.0 days 60 60 24))
72 (ms (condition-case nil (floor (/ seconds rest))
73 (range-error (expt 2 16)))))
74 (list ms (condition-case nil (round (- seconds (* ms rest)))
75 (range-error (expt 2 16))))))
77 (defun time-since (time)
78 "Return the time since TIME, which is either an internal time or a date."
80 ;; Convert date strings to internal time.
81 (setq time (date-to-time time)))
82 (let* ((current (current-time))
83 (rest (when (< (nth 1 current) (nth 1 time))
85 (list (- (+ (car current) (if rest -1 0)) (car time))
86 (- (+ (or rest 0) (nth 1 current)) (nth 1 time)))))
88 (defun subtract-time (t1 t2)
89 "Subtract two internal times."
90 (let ((borrow (< (cadr t1) (cadr t2))))
91 (list (- (car t1) (car t2) (if borrow 1 0))
92 (- (+ (if borrow 65536 0) (cadr t1)) (cadr t2)))))
94 (defun date-to-day (date)
95 "Return the number of days between year 1 and DATE."
96 (time-to-days (date-to-time date)))
98 (defun days-between (date1 date2)
99 "Return the number of days between DATE1 and DATE2."
100 (- (date-to-day date1) (date-to-day date2)))
102 (defun date-leap-year-p (year)
103 "Return t if YEAR is a leap year."
104 (or (and (zerop (% year 4))
105 (not (zerop (% year 100))))
106 (zerop (% year 400))))
108 (defun time-to-day-in-year (time)
109 "Return the day number within the year of the date month/day/year."
110 (let* ((tim (decode-time time))
114 (day-of-year (+ day (* 31 (1- month)))))
116 (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
117 (when (date-leap-year-p year)
118 (setq day-of-year (1+ day-of-year))))
121 (defun time-to-days (time)
122 "The number of days between the Gregorian date 0001-12-31bce and TIME.
123 The Gregorian date Sunday, December 31, 1bce is imaginary."
124 (let* ((tim (decode-time time))
128 (+ (time-to-day-in-year time) ; Days this year
129 (* 365 (1- year)) ; + Days in prior years
130 (/ (1- year) 4) ; + Julian leap years
131 (- (/ (1- year) 100)) ; - century years
132 (/ (1- year) 400)))) ; + Gregorian leap years
134 (defun time-to-number-of-days (time)
135 "Return the number of days represented by TIME.
136 The number of days will be returned as a floating point number."
137 (/ (+ (* 1.0 65536 (car time)) (cadr time)) (* 60 60 24)))
140 (defun safe-date-to-time (date)
141 "Parse DATE and return a time structure.
142 If DATE is malformed, a zero time will be returned."
149 ;;; time-date.el ends here