From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: 63861@debbugs.gnu.org
Subject: bug#63861: [PATCH] pp.el: New "pretty printing" code
Date: Fri, 02 Jun 2023 18:50:57 -0400 [thread overview]
Message-ID: <jwvh6rp8omm.fsf@iro.umontreal.ca> (raw)
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Tags: patch
I've often been annoyed by the way `ielm` "pretty prints" data,
so I wrote my own pretty printer, which has evolved over the years.
I believe it has finally reached a state which may be acceptable
to more than just myself.
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?
Stefan
In GNU Emacs 30.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
version 1.16.0, Xaw3d scroll bars) of 2023-05-24 built on pastel
Repository revision: 41b6b907d4cf2f8c302647dc63c5d9c94f9f01d6
Repository branch: work
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)
Configured using:
'configure -C --enable-checking --enable-check-lisp-object-type --with-modules --with-cairo --with-tiff=ifavailable
'CFLAGS=-Wall -g3 -Og -Wno-pointer-sign'
PKG_CONFIG_PATH=/home/monnier/lib/pkgconfig'
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From f26455b6b36f02fcb0954d5a440e8e97a0070b26 Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Fri, 2 Jun 2023 18:42:55 -0400
Subject: [PATCH] pp.el: New "pretty printing" code
Provide a new pretty printing code which tries to generate code
a bit more like what humans tend to write. The new code is driven
by the assumption that we want the output to fit within `fill-column`
(which clearly works poorly with deeply indented code which just can't
fit within `fill-column`).
* lisp/emacs-lisp/pp.el (pp--within-fill-column-p, pp-region): New funs.
(pp-buffer-use-pp-region): New custom var.
(pp-buffer): Use it.
---
lisp/emacs-lisp/pp.el | 94 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 93 insertions(+), 1 deletion(-)
diff --git a/lisp/emacs-lisp/pp.el b/lisp/emacs-lisp/pp.el
index e6e3cd6c6f4..3f9f4a5fbba 100644
--- a/lisp/emacs-lisp/pp.el
+++ b/lisp/emacs-lisp/pp.el
@@ -74,11 +74,103 @@ 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)))
+ (while (< (point) end)
+ (forward-comment (point-max))
+ (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))))
+ (when (natnump lif)
+ (goto-char (match-end 0))
+ (forward-sexp lif)
+ (insert "\n")
+ (indent-according-to-mode)))))
+ (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.
+ (skip-chars-forward ")]}")
+ (unless (eolp) (insert "\n") (indent-according-to-mode)))))))
+
+(defcustom pp-buffer-use-pp-region nil
+ "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))
+ (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)
@@ -98,7 +190,7 @@ pp-buffer
(insert ?\n))
(t (goto-char (point-max)))))
(goto-char (point-min))
- (indent-sexp))
+ (indent-sexp)))
;;;###autoload
(defun pp (object &optional stream)
--
2.30.2
next reply other threads:[~2023-06-02 22:50 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-02 22:50 Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2023-06-03 5:53 ` bug#63861: [PATCH] pp.el: New "pretty printing" code Eli Zaretskii
2023-06-03 18:18 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-03 18:58 ` Eli Zaretskii
2023-06-12 20:21 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-13 10:55 ` Eli Zaretskii
2023-06-16 18:26 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-17 5:39 ` Eli Zaretskii
2023-06-17 16:13 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-17 16:42 ` Eli Zaretskii
2023-06-17 22:08 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-04 3:25 ` Visuwesh
2023-06-07 15:48 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-09 3:21 ` Visuwesh
2023-06-09 14:59 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-09 15:09 ` Ihor Radchenko
2023-06-09 15:26 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-09 15:59 ` Visuwesh
2023-06-09 16:04 ` Visuwesh
2023-06-05 16:12 ` Juri Linkov
2023-06-07 15:21 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-07 18:12 ` Juri Linkov
2023-06-07 19:43 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-07 14:10 ` Thierry Volpiatto
2023-06-07 15:27 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-07 16:19 ` Thierry Volpiatto
2023-06-07 21:18 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-08 16:15 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-08 18:08 ` Thierry Volpiatto
2023-06-08 22:35 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-09 0:07 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-06-09 5:22 ` Thierry Volpiatto
2023-06-20 20:56 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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