--- /dev/null
+;;; time-date.el --- Date and time handling functions
+;; Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+
+;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
+;; Masanobu Umeda <umerin@mse.kyutech.ac.jp>
+;; Keywords: mail news util
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING. If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'parse-time)
+
+(autoload 'timezone-make-date-arpa-standard "timezone")
+
+;;;###autoload
+(defun date-to-time (date)
+ "Parse a string that represents a date-time and return a time value."
+ (condition-case ()
+ (apply 'encode-time
+ (parse-time-string
+ ;; `parse-time-string' isn't sufficiently general or
+ ;; robust. It fails to grok some of the formats that
+ ;; timezone does (e.g. dodgy post-2000 stuff from some
+ ;; Elms) and either fails or returns bogus values. Lars
+ ;; reverted this change, but that loses non-trivially
+ ;; often for me. -- fx
+ (timezone-make-date-arpa-standard date)))
+ (error (error "Invalid date: %s" date))))
+
+(defun time-to-seconds (time)
+ "Convert time value TIME to a floating point number.
+You can use `float-time' instead."
+ (+ (* (car time) 65536.0)
+ (cadr time)
+ (/ (or (nth 2 time) 0) 1000000.0)))
+
+;;;###autoload
+(defun seconds-to-time (seconds)
+ "Convert SECONDS (a floating point number) to a time value."
+ (list (floor seconds 65536)
+ (floor (mod seconds 65536))
+ (floor (* (- seconds (ffloor seconds)) 1000000))))
+
+;;;###autoload
+(defun time-less-p (t1 t2)
+ "Say whether time value T1 is less than time value T2."
+ (or (< (car t1) (car t2))
+ (and (= (car t1) (car t2))
+ (< (nth 1 t1) (nth 1 t2)))))
+
+;;;###autoload
+(defun days-to-time (days)
+ "Convert DAYS into a time value."
+ (let* ((seconds (* 1.0 days 60 60 24))
+ (rest (expt 2 16))
+ (ms (condition-case nil (floor (/ seconds rest))
+ (range-error (expt 2 16)))))
+ (list ms (condition-case nil (round (- seconds (* ms rest)))
+ (range-error (expt 2 16))))))
+
+;;;###autoload
+(defun time-since (time)
+ "Return the time elapsed since TIME.
+TIME should be either a time value or a date-time string."
+ (when (stringp time)
+ ;; Convert date strings to internal time.
+ (setq time (date-to-time time)))
+ (let* ((current (current-time))
+ (rest (when (< (nth 1 current) (nth 1 time))
+ (expt 2 16))))
+ (list (- (+ (car current) (if rest -1 0)) (car time))
+ (- (+ (or rest 0) (nth 1 current)) (nth 1 time)))))
+
+;;;###autoload
+(defalias 'subtract-time 'time-subtract)
+
+;;;###autoload
+(defun time-subtract (t1 t2)
+ "Subtract two time values.
+Return the difference in the format of a time value."
+ (let ((borrow (< (cadr t1) (cadr t2))))
+ (list (- (car t1) (car t2) (if borrow 1 0))
+ (- (+ (if borrow 65536 0) (cadr t1)) (cadr t2)))))
+
+;;;###autoload
+(defun time-add (t1 t2)
+ "Add two time values. One should represent a time difference."
+ (let ((high (car t1))
+ (low (if (consp (cdr t1)) (nth 1 t1) (cdr t1)))
+ (micro (if (numberp (car-safe (cdr-safe (cdr t1))))
+ (nth 2 t1)
+ 0))
+ (high2 (car t2))
+ (low2 (if (consp (cdr t2)) (nth 1 t2) (cdr t2)))
+ (micro2 (if (numberp (car-safe (cdr-safe (cdr t2))))
+ (nth 2 t2)
+ 0)))
+ ;; Add
+ (setq micro (+ micro micro2))
+ (setq low (+ low low2))
+ (setq high (+ high high2))
+
+ ;; Normalize
+ ;; `/' rounds towards zero while `mod' returns a positive number,
+ ;; so we can't rely on (= a (+ (* 100 (/ a 100)) (mod a 100))).
+ (setq low (+ low (/ micro 1000000) (if (< micro 0) -1 0)))
+ (setq micro (mod micro 1000000))
+ (setq high (+ high (/ low 65536) (if (< low 0) -1 0)))
+ (setq low (logand low 65535))
+
+ (list high low micro)))
+
+;;;###autoload
+(defun date-to-day (date)
+ "Return the number of days between year 1 and DATE.
+DATE should be a date-time string."
+ (time-to-days (date-to-time date)))
+
+;;;###autoload
+(defun days-between (date1 date2)
+ "Return the number of days between DATE1 and DATE2.
+DATE1 and DATE2 should be date-time strings."
+ (- (date-to-day date1) (date-to-day date2)))
+
+;;;###autoload
+(defun date-leap-year-p (year)
+ "Return t if YEAR is a leap year."
+ (or (and (zerop (% year 4))
+ (not (zerop (% year 100))))
+ (zerop (% year 400))))
+
+;;;###autoload
+(defun time-to-day-in-year (time)
+ "Return the day number within the year of the date month/day/year."
+ (let* ((tim (decode-time time))
+ (month (nth 4 tim))
+ (day (nth 3 tim))
+ (year (nth 5 tim))
+ (day-of-year (+ day (* 31 (1- month)))))
+ (when (> month 2)
+ (setq day-of-year (- day-of-year (/ (+ 23 (* 4 month)) 10)))
+ (when (date-leap-year-p year)
+ (setq day-of-year (1+ day-of-year))))
+ day-of-year))
+
+;;;###autoload
+(defun time-to-days (time)
+ "The number of days between the Gregorian date 0001-12-31bce and TIME.
+TIME should be a time value.
+The Gregorian date Sunday, December 31, 1bce is imaginary."
+ (let* ((tim (decode-time time))
+ (month (nth 4 tim))
+ (day (nth 3 tim))
+ (year (nth 5 tim)))
+ (+ (time-to-day-in-year time) ; Days this year
+ (* 365 (1- year)) ; + Days in prior years
+ (/ (1- year) 4) ; + Julian leap years
+ (- (/ (1- year) 100)) ; - century years
+ (/ (1- year) 400)))) ; + Gregorian leap years
+
+(defun time-to-number-of-days (time)
+ "Return the number of days represented by TIME.
+The number of days will be returned as a floating point number."
+ (/ (+ (* 1.0 65536 (car time)) (cadr time)) (* 60 60 24)))
+
+;;;###autoload
+(defun safe-date-to-time (date)
+ "Parse a string that represents a date-time and return a time value.
+If DATE is malformed, return a time value of zeros."
+ (condition-case ()
+ (date-to-time date)
+ (error '(0 0))))
+
+(provide 'time-date)
+
+;;; arch-tag: addcf07b-b20a-465b-af72-550b8ac5190f
+;;; time-date.el ends here
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