From 2f181d60323bd9e0196775828de633100479f4c2 Mon Sep 17 00:00:00 2001 From: Stefan Monnier Date: Fri, 16 Jun 2023 13:35:06 -0400 Subject: [PATCH] pp.el (pp-fill): New default pp function * lisp/emacs-lisp/pp.el (pp-default-function): Change default. (pp--within-fill-column-p): New helper function. (pp-fill): New function. --- lisp/emacs-lisp/pp.el | 91 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 90 insertions(+), 1 deletion(-) diff --git a/lisp/emacs-lisp/pp.el b/lisp/emacs-lisp/pp.el index d0356234384..88ce5cb3ee8 100644 --- a/lisp/emacs-lisp/pp.el +++ b/lisp/emacs-lisp/pp.el @@ -54,7 +54,7 @@ large lists." :version "29.1") (make-obsolete-variable 'pp-use-max-width 'pp-default-function "30.1") -(defcustom pp-default-function #'pp-29 +(defcustom pp-default-function #'pp-fill ;; FIXME: The best pretty printer to use depends on the use-case ;; so maybe we should allow callers to specify what they want (maybe with ;; options like `fast', `compact', `code', `data', ...) and these @@ -68,6 +68,7 @@ That function can be called in one of two ways: In both cases, the function can presume that the buffer is setup for Lisp syntax." :type '(choice + (const :tag "Fit within `fill-column'" pp-fill) (const :tag "Emacs<29 algorithm, fast and good enough" pp-28) (const :tag "Work hard for code (slow on large inputs)" pp-emacs-lisp-code) @@ -143,6 +144,94 @@ Optional argument PP-FUNCTION overrides `pp-default-function'." (funcall (or pp-function pp-default-function) object) (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-fill (beg &optional end) + "Break lines in Lisp code between BEG and END so it fits within `fill-column'. +Presumes the current buffer has syntax and 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. +Can also be called with a single argument, in which case +it inserts and pretty-prints that arg at point." + (interactive "r") + (if (null end) (pp--object beg #'pp-fill) + (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-fill (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))))))) + ;;;###autoload (defun pp-buffer () "Prettify the current buffer with printed representation of a Lisp object." -- 2.39.2