Package: emacs;
Reported by: Stefan Monnier <monnier <at> iro.umontreal.ca>
Date: Fri, 2 Jun 2023 22:52:02 UTC
Severity: normal
Tags: patch
Done: Stefan Monnier <monnier <at> iro.umontreal.ca>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: Stefan Monnier <monnier <at> iro.umontreal.ca> To: Thierry Volpiatto <thievol <at> posteo.net> Cc: 63861 <at> debbugs.gnu.org Subject: bug#63861: [PATCH] pp.el: New "pretty printing" code Date: Thu, 08 Jun 2023 12:15:47 -0400
>> The new code is in a new function `pp-region`.
>> The old code redirects to the new code if `pp-buffer-use-pp-region` is
>> non-nil, tho I'm not sure we want to bother users with such
>> a config var. Hopefully, the new code should be good enough that users
>> don't need to choose. Maybe I should make it a `defvar` and have it
>> default to t, so new users will complain if it's not good enough?
>
> I tried your code and it looks very slow (but looks nice once printed).
> Testing on my bookmark-alist printed in some buffer.
> Here with a slightly modified version of pp-buffer (not much faster than
> the original one):
>
> (benchmark-run-compiled 1 (pp-buffer))
> => (6.942135047 0 0.0)
> And here with your version (using pp-region):
> (benchmark-run-compiled 1 (pp-buffer))
> => (46.141411097 0 0.0)
Hmm... that's weird. With the bookmark-alist.el file you sent me,
I get pretty much the reverse result:
% for f in foo.el test-load-history.el test-bookmark-alist.el; do \
for v in nil t; do \
time src/emacs -Q --batch "$f" -l pp \
--eval "(progn (setq pp-buffer-use-pp-region $v) \
(message \"%s %s %S\" (file-name-nondirectory buffer-file-name) \
pp-buffer-use-pp-region \
(benchmark-run (pp-buffer))))"; \
done; done
foo.el nil (0.210123295 1 0.057426385)
src/emacs -Q --batch "$f" -l pp --eval 0.34s user 0.04s system 99% cpu 0.382 total
foo.el t (0.07107641199999999 0 0.0)
src/emacs -Q --batch "$f" -l pp --eval 0.19s user 0.03s system 99% cpu 0.222 total
test-load-history.el nil (156.07942386099998 17 1.432754161)
src/emacs -Q --batch "$f" -l pp --eval 156.04s user 0.20s system 99% cpu 2:36.26 total
test-load-history.el t (96.480110987 24 1.9799413479999999)
src/emacs -Q --batch "$f" -l pp --eval 96.40s user 0.27s system 99% cpu 1:36.69 total
test-bookmark-alist.el nil (51.211047973 8 0.6690439610000001)
src/emacs -Q --batch "$f" -l pp --eval 51.29s user 0.11s system 99% cpu 51.401 total
test-bookmark-alist.el t (5.110458941 6 0.468187075)
src/emacs -Q --batch "$f" -l pp --eval 5.21s user 0.09s system 99% cpu 5.302 total
%
This is comparing "the old pp-buffer" with "the new `pp-region`", using
the patch below. This is not using your `tv/pp-region` code.
I find these results (mine) quite odd: they suggest that my `pp-region`
is *faster* than the old `pp-buffer` for `load-history` and `bookmark-alist`
data, which I definitely did not expect (and don't know how to explain
either).
These tests were run on a machine whose CPU's speed can vary quite
drastically depending on the load, so take those numbers with a grain of
salt, but the dynamic frequency fluctuations shouldn't cause more than
a factor of 2 difference (and according to my CPU frequency monitor
widget, the frequency was reasonably stable during the test).
> For describe variable I use a modified version of `pp` which is very
> fast (nearly instant to pretty print value above) but maybe unsafe with
> some vars, didn't have any problems though, see
> https://github.com/thierryvolpiatto/emacs-config/blob/main/describe-variable.el.
So, IIUC the numbers you cite above compare my `pp-region` to your
`tv/pp-region`, right? And do I understand correctly that
`tv/pp-region` does not indent its output?
What was the reason for this choice?
Stefan
PS: BTW, looking at the output of `pp` on the bookmark-data, it's not
a test where `pp-region` shines: the old pp uses up more lines, but is
more regular and arguably more readable :-(
diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index d44c9d6e23d..9914ededb85 100644
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -876,7 +876,7 @@ lisp-ppss
2 (counting from 0). This is important for Lisp indentation."
(unless pos (setq pos (point)))
(let ((pss (syntax-ppss pos)))
- (if (nth 9 pss)
+ (if (and (not (nth 2 pss)) (nth 9 pss))
(let ((sexp-start (car (last (nth 9 pss)))))
(parse-partial-sexp sexp-start pos nil nil (syntax-ppss sexp-start)))
pss)))
diff --git a/lisp/emacs-lisp/pp.el b/lisp/emacs-lisp/pp.el
index e6e3cd6c6f4..89d7325a491 100644
--- a/lisp/emacs-lisp/pp.el
+++ b/lisp/emacs-lisp/pp.el
@@ -74,31 +74,127 @@ pp-to-string
(pp-buffer)
(buffer-string))))
+(defun pp--within-fill-column-p ()
+ "Return non-nil if point is within `fill-column'."
+ ;; Try and make it O(fill-column) rather than O(current-column),
+ ;; so as to avoid major slowdowns on long lines.
+ ;; FIXME: This doesn't account for invisible text or `display' properties :-(
+ (and (save-excursion
+ (re-search-backward
+ "^\\|\n" (max (point-min) (- (point) fill-column)) t))
+ (<= (current-column) fill-column)))
+
+(defun pp-region (beg end)
+ "Insert newlines in BEG..END to try and fit within `fill-column'.
+Presumes the current buffer contains Lisp code and has indentation properly
+configured for that.
+Designed under the assumption that the region occupies a single line,
+tho it should also work if that's not the case."
+ (interactive "r")
+ (goto-char beg)
+ (let ((end (copy-marker end t))
+ (newline (lambda ()
+ (skip-chars-forward ")]}")
+ (unless (save-excursion (skip-chars-forward " \t") (eolp))
+ (insert "\n")
+ (indent-according-to-mode)))))
+ (while (progn (forward-comment (point-max))
+ (< (point) end))
+ (let ((beg (point))
+ ;; Whether we're in front of an element with paired delimiters.
+ ;; Can be something funky like #'(lambda ..) or ,'#s(...).
+ (paired (when (looking-at "['`,#]*[[:alpha:]]*\\([({[\"]\\)")
+ (match-beginning 1))))
+ ;; Go to the end of the sexp.
+ (goto-char (or (scan-sexps (or paired (point)) 1) end))
+ (unless
+ (and
+ ;; The sexp is all on a single line.
+ (save-excursion (not (search-backward "\n" beg t)))
+ ;; And its end is within `fill-column'.
+ (or (pp--within-fill-column-p)
+ ;; If the end of the sexp is beyond `fill-column',
+ ;; try to move the sexp to its own line.
+ (and
+ (save-excursion
+ (goto-char beg)
+ (if (save-excursion (skip-chars-backward " \t({[',") (bolp))
+ ;; The sexp was already on its own line.
+ nil
+ (skip-chars-backward " \t")
+ (setq beg (copy-marker beg t))
+ (if paired (setq paired (copy-marker paired t)))
+ ;; We could try to undo this insertion if it
+ ;; doesn't reduce the indentation depth, but I'm
+ ;; not sure it's worth the trouble.
+ (insert "\n") (indent-according-to-mode)
+ t))
+ ;; Check again if we moved the whole exp to a new line.
+ (pp--within-fill-column-p))))
+ ;; The sexp is spread over several lines, and/or its end is
+ ;; (still) beyond `fill-column'.
+ (when (and paired (not (eq ?\" (char-after paired))))
+ ;; The sexp has sub-parts, so let's try and spread
+ ;; them over several lines.
+ (save-excursion
+ (goto-char beg)
+ (when (looking-at "(\\([^][()\" \t\n;']+\\)")
+ ;; Inside an expression of the form (SYM ARG1
+ ;; ARG2 ... ARGn) where SYM has a `lisp-indent-function'
+ ;; property that's a number, insert a newline after
+ ;; the corresponding ARGi, because it tends to lead to
+ ;; more natural and less indented code.
+ (let* ((sym (intern-soft (match-string 1)))
+ (lif (and sym (get sym 'lisp-indent-function))))
+ (if (eq lif 'defun) (setq lif 2))
+ (when (natnump lif)
+ (goto-char (match-end 0))
+ (forward-sexp lif)
+ (funcall newline)))))
+ (save-excursion
+ (pp-region (1+ paired) (1- (point)))))
+ ;; Now the sexp either ends beyond `fill-column' or is
+ ;; spread over several lines (or both). Either way, the rest of the
+ ;; line should be moved to its own line.
+ (funcall newline))))))
+
+(defcustom pp-buffer-use-pp-region t
+ "If non-nil, `pp-buffer' uses the new `pp-region' code."
+ :type 'boolean)
+
;;;###autoload
(defun pp-buffer ()
"Prettify the current buffer with printed representation of a Lisp object."
(interactive)
(goto-char (point-min))
- (while (not (eobp))
- (cond
- ((ignore-errors (down-list 1) t)
- (save-excursion
- (backward-char 1)
- (skip-chars-backward "'`#^")
- (when (and (not (bobp)) (memq (char-before) '(?\s ?\t ?\n)))
- (delete-region
- (point)
- (progn (skip-chars-backward " \t\n") (point)))
- (insert "\n"))))
- ((ignore-errors (up-list 1) t)
- (skip-syntax-forward ")")
- (delete-region
- (point)
- (progn (skip-chars-forward " \t\n") (point)))
- (insert ?\n))
- (t (goto-char (point-max)))))
- (goto-char (point-min))
- (indent-sexp))
+ (if pp-buffer-use-pp-region
+ (with-syntax-table emacs-lisp-mode-syntax-table
+ (let ((fill-column (max fill-column 70))
+ (indent-line-function
+ (if (local-variable-p 'indent-line-function)
+ indent-line-function
+ #'lisp-indent-line)))
+ (pp-region (point-min) (point-max))))
+ (while (not (eobp))
+ (cond
+ ((ignore-errors (down-list 1) t)
+ (save-excursion
+ (backward-char 1)
+ (skip-chars-backward "'`#^")
+ (when (and (not (bobp)) (memq (char-before) '(?\s ?\t ?\n)))
+ (delete-region
+ (point)
+ (progn (skip-chars-backward " \t\n") (point)))
+ (insert "\n"))))
+ ((ignore-errors (up-list 1) t)
+ (skip-syntax-forward ")")
+ (delete-region
+ (point)
+ (progn (skip-chars-forward " \t\n") (point)))
+ (insert ?\n))
+ (t (goto-char (point-max)))))
+ (goto-char (point-min))
+ (indent-sexp)))
;;;###autoload
(defun pp (object &optional stream)
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