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;;; time-date.el --- Date and time handling functions
;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2005
;; 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., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Commentary:
;; Time values come in three formats. The oldest format is a cons
;; cell of the form (HIGH . LOW). This format is obsolete, but still
;; supported. The two other formats are the lists (HIGH LOW) and
;; (HIGH LOW MICRO). The first two formats specify HIGH * 2^16 + LOW
;; seconds; the third format specifies HIGH * 2^16 + LOW + MICRO /
;; 1000000 seconds. We should have 0 <= MICRO < 1000000 and 0 <= LOW
;; < 2^16. If the time value represents a point in time, then HIGH is
;; nonnegative. If the time value is a time difference, then HIGH can
;; be negative as well. The macro `with-decoded-time-value' and the
;; function `encode-time-value' make it easier to deal with these
;; three formats. See `time-subtract' for an example of how to use
;; them.
;;; Code:
(defmacro with-decoded-time-value (varlist &rest body)
"Decode a time value and bind it according to VARLIST, then eval BODY.
The value of the last form in BODY is returned.
Each element of the list VARLIST is a list of the form
\(HIGH-SYMBOL LOW-SYMBOL MICRO-SYMBOL [TYPE-SYMBOL] TIME-VALUE).
The time value TIME-VALUE is decoded and the result it bound to
the symbols HIGH-SYMBOL, LOW-SYMBOL and MICRO-SYMBOL.
The optional TYPE-SYMBOL is bound to the type of the time value.
Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH
LOW), and type 3 is the list (HIGH LOW MICRO)."
(declare (indent 1)
(debug ((&rest (symbolp symbolp symbolp &or [symbolp form] form))
body)))
(if varlist
(let* ((elt (pop varlist))
(high (pop elt))
(low (pop elt))
(micro (pop elt))
(type (unless (eq (length elt) 1)
(pop elt)))
(time-value (car elt))
(gensym (make-symbol "time")))
`(let* ,(append `((,gensym ,time-value)
(,high (pop ,gensym))
,low ,micro)
(when type `(,type)))
(if (consp ,gensym)
(progn
(setq ,low (pop ,gensym))
(if ,gensym
,(append `(setq ,micro (car ,gensym))
(when type `(,type 2)))
,(append `(setq ,micro 0)
(when type `(,type 1)))))
,(append `(setq ,low ,gensym ,micro 0)
(when type `(,type 0))))
(with-decoded-time-value ,varlist ,@body)))
`(progn ,@body)))
(defun encode-time-value (high low micro type)
"Encode HIGH, LOW, and MICRO into a time value of type TYPE.
Type 0 is the cons cell (HIGH . LOW), type 1 is the list (HIGH LOW),
and type 3 is the list (HIGH LOW MICRO)."
(cond
((eq type 0) (cons high low))
((eq type 1) (list high low))
((eq type 2) (list high low micro))))
(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))))
;;;###autoload
(defun time-to-seconds (time)
"Convert time value TIME to a floating point number.
You can use `float-time' instead."
(with-decoded-time-value ((high low micro time))
(+ (* 1.0 high 65536)
low
(/ micro 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."
(with-decoded-time-value ((high1 low1 micro1 t1)
(high2 low2 micro2 t2))
(or (< high1 high2)
(and (= high1 high2)
(or (< low1 low2)
(and (= low1 low2)
(< micro1 micro2)))))))
;;;###autoload
(defun days-to-time (days)
"Convert DAYS into a time value."
(let* ((seconds (* 1.0 days 60 60 24))
(high (condition-case nil (floor (/ seconds 65536))
(range-error most-positive-fixnum))))
(list high (condition-case nil (floor (- seconds (* 1.0 high 65536)))
(range-error 65535)))))
;;;###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)))
(time-subtract (current-time) 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."
(with-decoded-time-value ((high low micro type t1)
(high2 low2 micro2 type2 t2))
(setq high (- high high2)
low (- low low2)
micro (- micro micro2)
type (max type type2))
(when (< micro 0)
(setq low (1- low)
micro (+ micro 1000000)))
(when (< low 0)
(setq high (1- high)
low (+ low 65536)))
(encode-time-value high low micro type)))
;;;###autoload
(defun time-add (t1 t2)
"Add two time values. One should represent a time difference."
(with-decoded-time-value ((high low micro type t1)
(high2 low2 micro2 type2 t2))
(setq high (+ high high2)
low (+ low low2)
micro (+ micro micro2)
type (max type type2))
(when (>= micro 1000000)
(setq low (1+ low)
micro (- micro 1000000)))
(when (>= low 65536)
(setq high (1+ high)
low (- low 65536)))
(encode-time-value high low micro type)))
;;;###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 corresponding to TIME."
(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."
(/ (time-to-seconds 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
|
