* Re: master 4cc4344: ; Clarify and simplify time-stamp comments
[not found] ` <20210926152521.5401420A5E@vcs0.savannah.gnu.org>
@ 2021-10-14 14:19 ` Lars Ingebrigtsen
2021-10-15 3:41 ` Stephen Gildea
0 siblings, 1 reply; 2+ messages in thread
From: Lars Ingebrigtsen @ 2021-10-14 14:19 UTC (permalink / raw)
To: emacs-devel; +Cc: Stephen Gildea
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stepheng+savannah@gildea.com (Stephen Gildea) writes:
> ; Clarify and simplify time-stamp comments
I'm going through some old stuff I've got stashed in my Emacs git tree,
and I found something I was working on in 2019, but don't remember the
status of.
The main idea behind this patch (which no longer applies) is that we
could rewrite `time-stamp-string-preprocess' to just use `format-spec'.
I vaguely remember there being some corner case that `format-spec'
didn't support yet, but you've simplified the time-spec syntax a bit
meanwhile, so perhaps it's possible now.
Anyway, I'm just including the patch below -- perhaps it can be used for
inspiration, but if not, just disregard it.
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[-- Attachment #2: time-stamp.patch --]
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diff --git a/lisp/time-stamp.el b/lisp/time-stamp.el
index f423683852..8157abbb3c 100644
--- a/lisp/time-stamp.el
+++ b/lisp/time-stamp.el
@@ -36,6 +36,8 @@
;;; Code:
+(require 'format-spec)
+
(defgroup time-stamp nil
"Maintain last change time stamps in files edited by Emacs."
:group 'data
@@ -413,192 +415,33 @@ time-stamp-string
(defconst time-stamp-no-file "(no file)"
"String to use when the buffer is not associated with a file.")
-;;; FIXME This comment was written in 1996!
-;;; time-stamp is transitioning to using the new, expanded capabilities
-;;; of format-time-string. During the process, this function implements
-;;; intermediate, compatible formats and complains about old, soon to
-;;; be unsupported, formats. This function will get a lot (a LOT) shorter
-;;; when the transition is complete and we can just pass most things
-;;; straight through to format-time-string.
-;;; At all times, all the formats recommended in the doc string
-;;; of time-stamp-format will work not only in the current version of
-;;; Emacs, but in all versions that have been released within the past
-;;; two years.
-;;; The : modifier is a temporary conversion feature used to resolve
-;;; ambiguous formats--formats that are changing (over time) incompatibly.
(defun time-stamp-string-preprocess (format &optional time)
"Use a FORMAT to format date, time, file, and user information.
Optional second argument TIME is only for testing.
Implements non-time extensions to `format-time-string'
and all `time-stamp-format' compatibility."
- (let ((fmt-len (length format))
- (ind 0)
- cur-char
- (prev-char nil)
- (result "")
- field-width
- field-result
- alt-form change-case
- (paren-level 0))
- (while (< ind fmt-len)
- (setq cur-char (aref format ind))
- (setq
- result
- (concat result
- (cond
- ((eq cur-char ?%)
- ;; eat any additional args to allow for future expansion
- (setq alt-form nil change-case nil field-width "")
- (while (progn
- (setq ind (1+ ind))
- (setq cur-char (if (< ind fmt-len)
- (aref format ind)
- ?\0))
- (or (eq ?. cur-char)
- (eq ?, cur-char) (eq ?: cur-char) (eq ?@ cur-char)
- (eq ?- cur-char) (eq ?+ cur-char) (eq ?_ cur-char)
- (eq ?\s cur-char) (eq ?# cur-char) (eq ?^ cur-char)
- (and (eq ?\( cur-char)
- (not (eq prev-char ?\\))
- (setq paren-level (1+ paren-level)))
- (if (and (eq ?\) cur-char)
- (not (eq prev-char ?\\))
- (> paren-level 0))
- (setq paren-level (1- paren-level))
- (and (> paren-level 0)
- (< ind fmt-len)))
- (if (and (<= ?0 cur-char) (>= ?9 cur-char))
- ;; get format width
- (let ((field-index ind))
- (while (progn
- (setq ind (1+ ind))
- (setq cur-char (if (< ind fmt-len)
- (aref format ind)
- ?\0))
- (and (<= ?0 cur-char) (>= ?9 cur-char))))
- (setq field-width (substring format field-index ind))
- (setq ind (1- ind))
- t))))
- (setq prev-char cur-char)
- ;; some characters we actually use
- (cond ((eq cur-char ?:)
- (setq alt-form t))
- ((eq cur-char ?#)
- (setq change-case t))))
- (setq field-result
- (cond
- ((eq cur-char ?%)
- "%%")
- ((eq cur-char ?a) ;day of week
- (if change-case
- (time-stamp--format "%#a" time)
- (or alt-form (not (string-equal field-width ""))
- (time-stamp-conv-warn "%a" "%:a"))
- (if (and alt-form (not (string-equal field-width "")))
- "" ;discourage "%:3a"
- (time-stamp--format "%A" time))))
- ((eq cur-char ?A)
- (if alt-form
- (time-stamp--format "%A" time)
- (or change-case (not (string-equal field-width ""))
- (time-stamp-conv-warn "%A" "%#A"))
- (time-stamp--format "%#A" time)))
- ((eq cur-char ?b) ;month name
- (if change-case
- (time-stamp--format "%#b" time)
- (or alt-form (not (string-equal field-width ""))
- (time-stamp-conv-warn "%b" "%:b"))
- (if (and alt-form (not (string-equal field-width "")))
- "" ;discourage "%:3b"
- (time-stamp--format "%B" time))))
- ((eq cur-char ?B)
- (if alt-form
- (time-stamp--format "%B" time)
- (or change-case (not (string-equal field-width ""))
- (time-stamp-conv-warn "%B" "%#B"))
- (time-stamp--format "%#B" time)))
- ((eq cur-char ?d) ;day of month, 1-31
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?H) ;hour, 0-23
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?I) ;hour, 1-12
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?m) ;month number, 1-12
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?M) ;minute, 0-59
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?p) ;am or pm
- (or change-case
- (time-stamp-conv-warn "%p" "%#p"))
- (time-stamp--format "%#p" time))
- ((eq cur-char ?P) ;AM or PM
- (time-stamp--format "%p" time))
- ((eq cur-char ?S) ;seconds, 00-60
- (time-stamp-do-number cur-char alt-form field-width time))
- ((eq cur-char ?w) ;weekday number, Sunday is 0
- (time-stamp--format "%w" time))
- ((eq cur-char ?y) ;year
- (or alt-form (not (string-equal field-width ""))
- (time-stamp-conv-warn "%y" "%:y"))
- (string-to-number (time-stamp--format "%Y" time)))
- ((eq cur-char ?Y) ;4-digit year, new style
- (string-to-number (time-stamp--format "%Y" time)))
- ((eq cur-char ?z) ;time zone lower case
- (if change-case
- "" ;discourage %z variations
- (time-stamp--format "%#Z" time)))
- ((eq cur-char ?Z)
- (if change-case
- (time-stamp--format "%#Z" time)
- (time-stamp--format "%Z" time)))
- ((eq cur-char ?f) ;buffer-file-name, base name only
- (if buffer-file-name
+ (format-spec
+ format
+ `((?f . ;buffer-file-name, base name only
+ ,(if buffer-file-name
(file-name-nondirectory buffer-file-name)
time-stamp-no-file))
- ((eq cur-char ?F) ;buffer-file-name, full path
- (or buffer-file-name
+ (?F . ;buffer-file-name, full path
+ ,(or buffer-file-name
time-stamp-no-file))
- ((eq cur-char ?s) ;system name
- (system-name))
- ((eq cur-char ?u) ;user name
- (user-login-name))
- ((eq cur-char ?U) ;user full name
- (user-full-name))
- ((eq cur-char ?l) ;logname (undocumented user name alt)
- (user-login-name))
- ((eq cur-char ?L) ;(undocumented alt user full name)
- (user-full-name))
- ((eq cur-char ?h) ;mail host name
- (or mail-host-address (system-name)))
- ((eq cur-char ?q) ;(undocumented unqual hostname)
- (let ((qualname (system-name)))
+ (?s . ,(system-name)) ; system name
+ (?u . ,(user-login-name)) ;user name
+ (?U . ,(user-full-name)) ;user full name
+ (?l . ,(user-login-name)) ;logname (undocumented user name alt)
+ (?L . ,(user-full-name)) ;(undocumented alt user full name)
+ (?h . ,(or mail-host-address (system-name))) ;mail host name
+ (?q . ;(undocumented unqual hostname)
+ ,(let ((qualname (system-name)))
(if (string-match "\\." qualname)
(substring qualname 0 (match-beginning 0))
qualname)))
- ((eq cur-char ?Q) ;(undocumented fully-qualified host)
- (system-name))
- ))
- (let ((padded-result
- (format (format "%%%s%c"
- field-width
- (if (numberp field-result) ?d ?s))
- (or field-result ""))))
- (let* ((initial-length (length padded-result))
- (desired-length (if (string-equal field-width "")
- initial-length
- (string-to-number field-width))))
- (if (> initial-length desired-length)
- ;; truncate strings on right, years on left
- (if (stringp field-result)
- (substring padded-result 0 desired-length)
- (if (eq cur-char ?y)
- (substring padded-result (- desired-length))
- padded-result)) ;non-year numbers don't truncate
- padded-result))))
- (t
- (char-to-string cur-char)))))
- (setq ind (1+ ind)))
- result))
+ (?Q , (system-name))) ;(undocumented fully-qualified host)
+ t))
(defun time-stamp-do-number (format-char alt-form field-width time)
"Handle compatible FORMAT-CHAR where only default width/padding will change.
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