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|
;;; rust-rustfmt.el --- Support for rustfmt -*- lexical-binding:t -*-
;;; Commentary:
;; This library implements support for "rustfmt", a tool for
;; formatting Rust code according to style guidelines.
;;; Code:
;;; Options
(defcustom rust-format-on-save nil
"Format future rust buffers before saving using rustfmt."
:type 'boolean
:safe #'booleanp
:group 'rust-mode)
(defcustom rust-format-show-buffer t
"Show *rustfmt* buffer if formatting detected problems."
:type 'boolean
:safe #'booleanp
:group 'rust-mode)
(defcustom rust-format-goto-problem t
"Jump to location of first detected problem when formatting buffer."
:type 'boolean
:safe #'booleanp
:group 'rust-mode)
(defcustom rust-rustfmt-bin "rustfmt"
"Path to rustfmt executable."
:type 'string
:group 'rust-mode)
(defcustom rust-rustfmt-switches '("--edition" "2018")
"Arguments to pass when invoking the `rustfmt' executable."
:type '(repeat string)
:group 'rust-mode)
;;; _
(defconst rust-rustfmt-buffername "*rustfmt*")
(defun rust--format-call (buf)
"Format BUF using rustfmt."
(let ((path exec-path))
(with-current-buffer (get-buffer-create rust-rustfmt-buffername)
(setq-local exec-path path)
(view-mode +1)
(let ((inhibit-read-only t))
(erase-buffer)
(insert-buffer-substring buf)
(let* ((tmpf (make-temp-file "rustfmt"))
(ret (apply #'call-process-region
(point-min)
(point-max)
rust-rustfmt-bin
t
`(t ,tmpf)
nil
rust-rustfmt-switches)))
(unwind-protect
(cond
((zerop ret)
(if (not (string= (buffer-string)
(with-current-buffer buf (buffer-string))))
;; replace-buffer-contents was in emacs 26.1, but it
;; was broken for non-ASCII strings, so we need 26.2.
(if (and (fboundp 'replace-buffer-contents)
(version<= "26.2" emacs-version))
(with-current-buffer buf
(replace-buffer-contents rust-rustfmt-buffername))
(copy-to-buffer buf (point-min) (point-max))))
(let ((win (get-buffer-window rust-rustfmt-buffername)))
(if win
(quit-window t win)
(kill-buffer rust-rustfmt-buffername))))
((= ret 3)
(if (not (string= (buffer-string)
(with-current-buffer buf (buffer-string))))
(copy-to-buffer buf (point-min) (point-max)))
(erase-buffer)
(insert-file-contents tmpf)
(rust--format-fix-rustfmt-buffer (buffer-name buf))
(error "Rustfmt could not format some lines, see %s buffer for details"
rust-rustfmt-buffername))
(t
(erase-buffer)
(insert-file-contents tmpf)
(rust--format-fix-rustfmt-buffer (buffer-name buf))
(error "Rustfmt failed, see %s buffer for details"
rust-rustfmt-buffername)))
(delete-file tmpf)))))))
;; Since we run rustfmt through stdin we get <stdin> markers in the
;; output. This replaces them with the buffer name instead.
(defun rust--format-fix-rustfmt-buffer (buffer-name)
(save-match-data
(with-current-buffer (get-buffer rust-rustfmt-buffername)
(let ((inhibit-read-only t)
(fixed (format "--> %s:" buffer-name)))
(goto-char (point-min))
(while (re-search-forward "--> \\(?:<stdin>\\|stdin\\):" nil t)
(replace-match fixed))))))
;; If rust-mode has been configured to navigate to source of the error
;; or display it, do so -- and return true. Otherwise return nil to
;; indicate nothing was done.
(defun rust--format-error-handler ()
(let ((ok nil))
(when rust-format-show-buffer
(display-buffer (get-buffer rust-rustfmt-buffername))
(setq ok t))
(when rust-format-goto-problem
(rust-goto-format-problem)
(setq ok t))
ok))
(defun rust-goto-format-problem ()
"Jumps to problem reported by rustfmt, if any.
In case of multiple problems cycles through them. Displays the
rustfmt complain in the echo area."
(interactive)
;; This uses position in *rustfmt* buffer to know which is the next
;; error to jump to, and source: line in the buffer to figure which
;; buffer it is from.
(let ((rustfmt (get-buffer rust-rustfmt-buffername)))
(if (not rustfmt)
(message "No %s, no problems." rust-rustfmt-buffername)
(let ((target-buffer (with-current-buffer rustfmt
(save-excursion
(goto-char (point-min))
(when (re-search-forward "--> \\([^:]+\\):" nil t)
(match-string 1)))))
(target-point (with-current-buffer rustfmt
;; No save-excursion, this is how we cycle through!
(let ((regex "--> [^:]+:\\([0-9]+\\):\\([0-9]+\\)"))
(when (or (re-search-forward regex nil t)
(progn (goto-char (point-min))
(re-search-forward regex nil t)))
(cons (string-to-number (match-string 1))
(string-to-number (match-string 2)))))))
(target-problem (with-current-buffer rustfmt
(save-excursion
(when (re-search-backward "^error:.+\n" nil t)
(forward-char (length "error: "))
(let ((p0 (point)))
(if (re-search-forward "\nerror:.+\n" nil t)
(buffer-substring p0 (point))
(buffer-substring p0 (point-max)))))))))
(when (and target-buffer (get-buffer target-buffer) target-point)
(switch-to-buffer target-buffer)
(goto-char (point-min))
(forward-line (1- (car target-point)))
(forward-char (1- (cdr target-point))))
(unless rust-format-show-buffer
(message target-problem))))))
(defconst rust--format-word "\
\\b\\(else\\|enum\\|fn\\|for\\|if\\|let\\|loop\\|\
match\\|struct\\|union\\|unsafe\\|while\\)\\b")
(defconst rust--format-line "\\(\n\\)")
;; Counts number of matches of regex beginning up to max-beginning,
;; leaving the point at the beginning of the last match.
(defun rust--format-count (regex max-beginning)
(let ((count 0)
save-point
beginning)
(while (and (< (point) max-beginning)
(re-search-forward regex max-beginning t))
(setq count (1+ count))
(setq beginning (match-beginning 1)))
;; try one more in case max-beginning lies in the middle of a match
(setq save-point (point))
(when (re-search-forward regex nil t)
(let ((try-beginning (match-beginning 1)))
(if (> try-beginning max-beginning)
(goto-char save-point)
(setq count (1+ count))
(setq beginning try-beginning))))
(when beginning (goto-char beginning))
count))
;; Gets list describing pos or (point).
;; The list contains:
;; 1. the number of matches of rust--format-word,
;; 2. the number of matches of rust--format-line after that,
;; 3. the number of columns after that.
(defun rust--format-get-loc (buffer &optional pos)
(with-current-buffer buffer
(save-excursion
(let ((pos (or pos (point)))
words lines columns)
(goto-char (point-min))
(setq words (rust--format-count rust--format-word pos))
(setq lines (rust--format-count rust--format-line pos))
(if (> lines 0)
(if (= (point) pos)
(setq columns -1)
(forward-char 1)
(goto-char pos)
(setq columns (current-column)))
(let ((initial-column (current-column)))
(goto-char pos)
(setq columns (- (current-column) initial-column))))
(list words lines columns)))))
;; Moves the point forward by count matches of regex up to max-pos,
;; and returns new max-pos making sure final position does not include another match.
(defun rust--format-forward (regex count max-pos)
(when (< (point) max-pos)
(let ((beginning (point)))
(while (> count 0)
(setq count (1- count))
(re-search-forward regex nil t)
(setq beginning (match-beginning 1)))
(when (re-search-forward regex nil t)
(setq max-pos (min max-pos (match-beginning 1))))
(goto-char beginning)))
max-pos)
;; Gets the position from a location list obtained using rust--format-get-loc.
(defun rust--format-get-pos (buffer loc)
(with-current-buffer buffer
(save-excursion
(goto-char (point-min))
(let ((max-pos (point-max))
(words (pop loc))
(lines (pop loc))
(columns (pop loc)))
(setq max-pos (rust--format-forward rust--format-word words max-pos))
(setq max-pos (rust--format-forward rust--format-line lines max-pos))
(when (> lines 0) (forward-char))
(let ((initial-column (current-column))
(save-point (point)))
(move-end-of-line nil)
(when (> (current-column) (+ initial-column columns))
(goto-char save-point)
(forward-char columns)))
(min (point) max-pos)))))
(defun rust-format-diff-buffer ()
"Show diff to current buffer from rustfmt.
Return the created process."
(interactive)
(unless (executable-find rust-rustfmt-bin)
(error "Could not locate executable %S" rust-rustfmt-bin))
(let* ((buffer
(with-current-buffer
(get-buffer-create "*rustfmt-diff*")
(let ((inhibit-read-only t))
(erase-buffer))
(current-buffer)))
(proc
(apply #'start-process
"rustfmt-diff"
buffer
rust-rustfmt-bin
"--check"
(cons (buffer-file-name)
rust-rustfmt-switches))))
(set-process-sentinel proc #'rust-format-diff-buffer-sentinel)
proc))
(defun rust-format-diff-buffer-sentinel (process _e)
(when (eq 'exit (process-status process))
(if (> (process-exit-status process) 0)
(with-current-buffer "*rustfmt-diff*"
(let ((inhibit-read-only t))
(diff-mode))
(pop-to-buffer (current-buffer)))
(message "rustfmt check passed."))))
(defun rust--format-buffer-using-replace-buffer-contents ()
(condition-case err
(progn
(rust--format-call (current-buffer))
(message "Formatted buffer with rustfmt."))
(error
(or (rust--format-error-handler)
(signal (car err) (cdr err))))))
(defun rust--format-buffer-saving-position-manually ()
(let* ((current (current-buffer))
(base (or (buffer-base-buffer current) current))
buffer-loc
window-loc)
(dolist (buffer (buffer-list))
(when (or (eq buffer base)
(eq (buffer-base-buffer buffer) base))
(push (list buffer
(rust--format-get-loc buffer nil))
buffer-loc)))
(dolist (frame (frame-list))
(dolist (window (window-list frame))
(let ((buffer (window-buffer window)))
(when (or (eq buffer base)
(eq (buffer-base-buffer buffer) base))
(let ((start (window-start window))
(point (window-point window)))
(push (list window
(rust--format-get-loc buffer start)
(rust--format-get-loc buffer point))
window-loc))))))
(condition-case err
(unwind-protect
;; save and restore window start position
;; after reformatting
;; to avoid the disturbing scrolling
(let ((w-start (window-start)))
(rust--format-call (current-buffer))
(set-window-start (selected-window) w-start)
(message "Formatted buffer with rustfmt."))
(dolist (loc buffer-loc)
(let* ((buffer (pop loc))
(pos (rust--format-get-pos buffer (pop loc))))
(with-current-buffer buffer
(goto-char pos))))
(dolist (loc window-loc)
(let* ((window (pop loc))
(buffer (window-buffer window))
(start (rust--format-get-pos buffer (pop loc)))
(pos (rust--format-get-pos buffer (pop loc))))
(unless (eq buffer current)
(set-window-start window start))
(set-window-point window pos))))
(error
(or (rust--format-error-handler)
(signal (car err) (cdr err)))))))
(defun rust-format-buffer ()
"Format the current buffer using rustfmt."
(interactive)
(unless (executable-find rust-rustfmt-bin)
(error "Could not locate executable \"%s\"" rust-rustfmt-bin))
;; If emacs version >= 26.2, we can use replace-buffer-contents to
;; preserve location and markers in buffer, otherwise we can try to
;; save locations as best we can, though we still lose markers.
(save-excursion
(if (version<= "26.2" emacs-version)
(rust--format-buffer-using-replace-buffer-contents)
(rust--format-buffer-saving-position-manually))))
(defun rust-enable-format-on-save ()
"Enable formatting using rustfmt when saving buffer."
(interactive)
(setq-local rust-format-on-save t))
(defun rust-disable-format-on-save ()
"Disable formatting using rustfmt when saving buffer."
(interactive)
(setq-local rust-format-on-save nil))
;;; Hooks
(defun rust-before-save-method ()
(when rust-format-on-save
(condition-case e
(rust-format-buffer)
(message (format "rust-before-save-hook: %S %S"
(car e)
(cdr e))))))
(defun rust-after-save-method ()
(when rust-format-on-save
(if (not (executable-find rust-rustfmt-bin))
(error "Could not locate executable \"%s\"" rust-rustfmt-bin)
(when (get-buffer rust-rustfmt-buffername)
;; KLDUGE: re-run the error handlers -- otherwise message area
;; would show "Wrote ..." instead of the error description.
(or (rust--format-error-handler)
(message "rustfmt detected problems, see %s for more."
rust-rustfmt-buffername))))))
;;; _
(provide 'rust-rustfmt)
;;; rust-rustfmt.el ends here
|
