Re: The format of time values in lisp/calendar/time-date.el.

[Lute Kamstra <Lute.Kamstra.lists@xs4all.nl>]

Richard Stallman <rms@gnu.org> writes:

>     Was there an evolution in format from (HIGH . LOW), via (HIGH LOW), to
>     (HIGH LOW MICRO)?
>
> Yes.  Both (HIGH LOW) and (HIGH LOW MICRO) are valid now.
> It is useful to accept (HIGH . LOW) as well.
>
>     Shall I fix time-less-p and time-subtract to deal with (HIGH LOW
>     MICRO) arguments as well?
>
> Yes, please do.
>
>     Should they deal with (HIGH . LOW) too?
>
> It would not be a bad thing.
>
>     What about the return value of time-subtract (and time-add): should it
>     be backward compatible in the sense that it returns (HIGH LOW) if both
>     its arguments are of that format?
>
> Yes.

Done.  Any objections to this patch?

Lute.


Index: lisp/ChangeLog
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/ChangeLog,v
retrieving revision 1.7106
diff -c -r1.7106 ChangeLog
*** lisp/ChangeLog	16 Mar 2005 13:21:20 -0000	1.7106
--- lisp/ChangeLog	16 Mar 2005 16:54:07 -0000
***************
*** 1,3 ****
--- 1,12 ----
+ 2005-03-16  Lute Kamstra  <lute@gnu.org>
+ 
+ 	* calendar/time-date.el: Add comment on time value formats.  Don't
+ 	require parse-time.
+ 	(time-to-seconds, time-less-p, time-since, time-subtract)
+ 	(time-add, time-to-number-of-days): Deal with all three formats of
+ 	time values.
+ 	(days-to-time): Return a valid time value when arg is huge.
+ 
  2005-03-16  Glenn Morris  <gmorris@ast.cam.ac.uk>
  
  	* calendar/diary-lib.el (mark-diary-entries): Use new optional
Index: lisp/calendar/time-date.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/calendar/time-date.el,v
retrieving revision 1.9
diff -c -r1.9 time-date.el
*** lisp/calendar/time-date.el	4 Sep 2004 13:13:48 -0000	1.9
--- lisp/calendar/time-date.el	16 Mar 2005 16:51:28 -0000
***************
*** 1,5 ****
  ;;; time-date.el --- date and time handling functions
! ;; Copyright (C) 1998, 1999, 2000, 2004 Free Software Foundation, Inc.
  
  ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
  ;;	Masanobu Umeda <umerin@mse.kyutech.ac.jp>
--- 1,5 ----
  ;;; time-date.el --- date and time handling functions
! ;; Copyright (C) 1998, 1999, 2000, 2004, 2005 Free Software Foundation, Inc.
  
  ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
  ;;	Masanobu Umeda <umerin@mse.kyutech.ac.jp>
***************
*** 24,32 ****
  
  ;;; Commentary:
  
! ;;; Code:
  
! (require 'parse-time)
  
  (autoload 'timezone-make-date-arpa-standard "timezone")
  
--- 24,41 ----
  
  ;;; 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.  See `time-subtract' for an example of how to
! ;; deal with these three formats.
  
! ;;; Code:
  
  (autoload 'timezone-make-date-arpa-standard "timezone")
  
***************
*** 49,81 ****
  (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)
--- 58,104 ----
  (defun time-to-seconds (time)
    "Convert time value TIME to a floating point number.
  You can use `float-time' instead."
!   (+ (* 1.0 (pop time) #x10000)
!      (if (consp time) (pop time) time)
!      (/ (if (numberp (car-safe time))
! 	    (car time)
! 	  0)
! 	1000000.0)))
  
  ;;;###autoload
  (defun seconds-to-time (seconds)
    "Convert SECONDS (a floating point number) to a time value."
!   (list (floor seconds #x10000)
! 	(floor (mod seconds #x10000))
  	(floor (* (- seconds (ffloor seconds)) 1000000))))
  
  ;;;###autoload
  (defun time-less-p (t1 t2)
    "Say whether time value T1 is less than time value T2."
!   (let* ((high1 (pop t1))
! 	 (low1 (if (consp t1) (pop t1) t1))
! 	 (micro1 (if (numberp (car-safe t1))
! 		     (car t1)
! 		   0))
! 	 (high2 (pop t2))
! 	 (low2 (if (consp t2) (pop t2) t2))
! 	 (micro2 (if (numberp (car-safe t2))
! 		     (car t2)
! 		   0)))
!     (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 #x10000))
! 		 (range-error most-positive-fixnum))))
!     (list high (condition-case nil (floor (- seconds (* 1.0 high #x10000)))
! 		 (range-error #xffff)))))
  
  ;;;###autoload
  (defun time-since (time)
***************
*** 84,94 ****
    (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)
--- 107,113 ----
    (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)
***************
*** 97,133 ****
  (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)
--- 116,169 ----
  (defun time-subtract (t1 t2)
    "Subtract two time values.
  Return the difference in the format of a time value."
!   (let* ((high (- (pop t1) (pop t2)))
! 	 (low (- (if (consp t1) (pop t1) t1)
! 		 (if (consp t2) (pop t2) t2)))
! 	 (micro (- (if (numberp (car-safe t1))
! 		       (car t1)
! 		     0)
! 		   (if (numberp (car-safe t2))
! 		       (car t2)
! 		     0))))
!     (when (< micro 0)
!       (setq low (1- low)
! 	    micro (+ micro 1000000)))
!     (when (< low 0)
!       (setq high (1- high)
! 	    low (+ low #x10000)))
!     (cons high
! 	  (if (or (consp t1) (consp t2))
! 	      (cons low
! 		    (when (or (numberp (car-safe t1))
! 			      (numberp (car-safe t2)))
! 		      (list micro)))
! 	    low))))
  
  ;;;###autoload
  (defun time-add (t1 t2)
    "Add two time values.  One should represent a time difference."
!   (let* ((high (+ (pop t1) (pop t2)))
! 	 (low (+ (if (consp t1) (pop t1) t1)
! 		 (if (consp t2) (pop t2) t2)))
! 	 (micro (+ (if (numberp (car-safe t1))
! 		       (car t1)
! 		     0)
! 		   (if (numberp (car-safe t2))
! 		       (car t2)
! 		     0))))
!     (when (>= micro 1000000)
!       (setq low (1+ low)
! 	    micro (- micro 1000000)))
!     (when (>= low #x10000)
!       (setq high (1+ high)
! 	    low (- low #x10000)))
!     (cons high
! 	  (if (or (consp t1) (consp t2))
! 	      (cons low
! 		    (when (or (numberp (car-safe t1))
! 			      (numberp (car-safe t2)))
! 		      (list micro)))
! 	    low))))
  
  ;;;###autoload
  (defun date-to-day (date)
***************
*** 180,186 ****
  (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)
--- 216,222 ----
  (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)