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Implement multi-formatter and custom-args support
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* More than one formatter can be defined for one language. (Well, that
  it already possible to define more than one, but only one of them
  would be accessible to users.)

* User-defined command line arguments can optionally be passed to
  external formatters.

Issues #2, #6, #27
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@lassik
lassik committed Feb 19, 2020
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Showing 1 changed file with 150 additions and 56 deletions.
206 changes: 150 additions & 56 deletions format-all.el
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
;; Author: Lassi Kortela <lassi@lassi.io>
;; URL: https://github.com/lassik/emacs-format-all-the-code
;; Version: 0.1.0
;; Package-Requires: ((emacs "24") (cl-lib "0.5") (language-id "0.4"))
;; Package-Requires: ((emacs "24.3") (cl-lib "0.5") (language-id "0.4"))
;; Keywords: languages util
;; SPDX-License-Identifier: MIT
;;
Expand Down Expand Up @@ -117,6 +117,37 @@ is not guaranteed to be in any particular place, so `goto-char'
before editing the buffer. Narrowing may be in effect unless
STATUS is :reformatted.")

(defvar format-all--user-args nil
"Internal variable to temporarily store arguments for formatters.")

(defvar-local format-all-formatters nil
"Rules to select which formatter format-all uses.
The value is an association list.
The first item of each association is the name of a programming
language. (GitHub Linguist names are used.)
The remaining items are one or more formatters to use for that
language. Each formatter is either:
* a symbol (e.g. black, clang-format, rufo)
* a list whose first item is that symbol, and any remaining items
are extra command line arguments to pass to the formatter
If more than one formatter is given for the same language, all of
them are run as a chain, with the code from each formatter passed
to the next. The final code is from the last formatter. In case
any formatter in the chain is missing or fails to format the
code, the entire chain fails and the old code before formatting
is preserved.
You'll probably want to set this in a \".dir-locals.el\" file or
in a hook function. Any number of buffers can share the same
association list. Using \".dir-locals.el\" is convenient since
the rules for an entire source tree can be given in one file.")

(eval-when-compile
(defconst format-all--system-type
(cl-case system-type
Expand Down Expand Up @@ -264,7 +295,7 @@ or none of ROOT-FILES are found in any parent directories, the
working directory will be the one where the formatted file is.
ROOT-FILES is ignored for buffers that are not visiting a file."
(let ((ok-statuses (or ok-statuses '(0)))
(args (format-all--flatten-once args))
(args (append format-all--user-args (format-all--flatten-once args)))
(default-directory (format-all--locate-default-directory root-files)))
(when format-all-debug
(message "Format-All: Running: %s"
Expand Down Expand Up @@ -713,13 +744,6 @@ unofficial languages IDs are prefixed with \"_\"."
(if (not installer) ""
(format " You may be able to install it via %S." installer))))

(defun format-all--probe ()
"Internal helper function to get the formatter for the current buffer."
(let ((language (format-all--language-id-buffer)))
(cl-dolist (formatter (gethash language format-all--language-table)
(list nil nil))
(cl-return (list formatter language)))))

(defun format-all--formatter-executable (formatter)
"Internal helper function to get the external program for FORMATTER."
(let ((executable (gethash formatter format-all--executable-table)))
Expand Down Expand Up @@ -751,47 +775,110 @@ unofficial languages IDs are prefixed with \"_\"."
(let ((line-length (- (point-at-eol) (point-at-bol))))
(goto-char (+ (point) (min old-column line-length))))))

(defun format-all-buffer--with (formatter language)
"Internal helper function to format the current buffer.
Relies on FORMATTER and LANGUAGE from `format-all--probe'."
(when format-all-debug
(message "Format-All: Formatting %s using %S"
(buffer-name) (list formatter language)))
(let ((f-function (gethash formatter format-all--format-table))
(executable (format-all--formatter-executable formatter)))
(cl-destructuring-bind (output errput)
(funcall f-function executable language)
(let ((status (cond ((null output) :error)
((equal t output) :already-formatted)
(t :reformatted))))
(when (equal :reformatted status)
(widen)
(format-all--save-line-number
(lambda ()
(erase-buffer)
(insert output))))
(format-all--show-or-hide-errors errput)
(run-hook-with-args 'format-all-after-format-functions
formatter status)
(message (cl-ecase status
(:error "Formatting error")
(:already-formatted "Already formatted")
(:reformatted "Reformatted!")))))))

(defun format-all-buffer--from-hook ()
(defun format-all--normalize-formatter (formatter)
"Internal function to convert FORMATTER spec into normal form."
(let ((formatter (if (listp formatter) formatter (list formatter))))
(when (cdr (last formatter))
(error "Formatter is not a proper list: %S" formatter))
(when (null formatter)
(error "Formatter name missing"))
(unless (symbolp (car formatter))
(error "Formatter name is not a symbol: %S" (car formatter)))
(unless (cl-every #'stringp (cdr formatter))
(error "Formatter command line arguments are not all strings: %S"
formatter))
formatter))

(defun format-all--normalize-chain (chain)
"Internal function to convert CHAIN spec into normal form."
(when (or (not (listp chain)) (cdr (last chain)))
(error "Formatter chain is not a proper list: %S" chain))
(mapcar #'format-all--normalize-formatter chain))

(defun format-all--run-chain (language chain)
"Internal function to run a formatter CHAIN on the current buffer.
LANGUAGE is the language ID of the current buffer, from
`format-all--language-id-buffer`."
(let* ((chain (format-all--normalize-chain chain))
(chain-tail chain)
(error-output "")
(reformatted-by '()))
(format-all--save-line-number
(lambda ()
(cl-loop
(unless (and chain-tail (= 0 (length error-output)))
(cl-return))
(let* ((formatter (car chain-tail))
(f-name (car formatter))
(f-args (cdr formatter))
(f-function (gethash f-name format-all--format-table))
(f-executable (format-all--formatter-executable f-name)))
(when format-all-debug
(message
"Format-All: Formatting %s as %s using %S%s"
(buffer-name) language f-name
(with-temp-buffer
(dolist (arg f-args) (insert " " (shell-quote-argument arg)))
(buffer-string))))
(cl-destructuring-bind (f-output f-error-output)
(let ((format-all--user-args f-args))
(funcall f-function f-executable language))
(let ((f-status :already-formatted))
(cond ((null f-output)
(setq error-output f-error-output)
(setq f-status :error))
((not (equal f-output t))
(setq reformatted-by
(append reformatted-by (list f-name)))
(erase-buffer)
(insert f-output)
(setq f-status :reformatted)))
(run-hook-with-args 'format-all-after-format-functions
f-name f-status))))
(setq chain-tail (cdr chain-tail)))
(format-all--show-or-hide-errors error-output)
(message "%s"
(cond ((not (= 0 (length error-output))) "Formatting error")
((not reformatted-by) "Already formatted")
(t "Reformatted!")))))))

(defun format-all--prompt-for-formatter (language)
"Internal function to choose a formatter for LANGUAGE."
(let ((f-names (gethash language format-all--language-table)))
(cond ((null f-names) (error "No supported formatters for %s" language))
((null (cdr f-names)) (car f-names))
(t (let ((f-string (completing-read
(format "Formatter for %s: " language)
(mapcar #'list f-names) nil t)))
(and (not (= 0 (length f-string)))
(intern f-string)))))))

(defun format-all--get-chain (language)
"Internal function to get LANGUAGE formatter chain for current buffer."
(when language (cdr (assoc language format-all-formatters))))

(defun format-all--set-chain (language chain)
"Internal function to set LANGUAGE formatter CHAIN for current buffer."
(cl-assert (stringp language))
(cl-assert (listp chain))
(setq format-all-formatters
(append (cl-remove-if (lambda (pair) (equal language (car pair)))
format-all-formatters)
(when chain (list (cons language chain))))))

(defun format-all--buffer-from-hook ()
"Internal helper function to auto-format current buffer from a hook.
Format-All installs this function into `before-save-hook' to
format buffers on save. This is a lenient version of
`format-all-buffer' that silently succeeds instead of signaling
an error if the current buffer has no formatter."
(cl-destructuring-bind (formatter language) (format-all--probe)
(when formatter
(format-all-buffer--with formatter language))))
(let ((language (format-all--language-id-buffer)))
(format-all--run-chain language (format-all--get-chain language))))

;;;###autoload
(defun format-all-buffer ()
(defun format-all-buffer (prompt-p)
"Auto-format the source code in the current buffer.
No disk files are touched - the buffer doesn't even need to be
Expand All @@ -801,21 +888,28 @@ use ordinary undo to get your code back to its previous state.
You will need to install external programs to do the formatting.
If the command can't find the program that it needs, it will try
to tell you how you might be able to install it on your operating
system. Only BibTeX, Emacs Lisp and Ledger are formatted without an
external program.
system. Only BibTeX, Emacs Lisp and Ledger are formatted without
an external program.
A suitable formatter is selected according to the `major-mode' of
the buffer. Many popular programming languages are supported.
It is fairly easy to add new languages that have an external
formatter.
the buffer. Many popular programming languages are supported. It
is fairly easy to add new languages that have an external
formatter. When called interactively or PROMPT-P is non-nil, a
missing formatter is prompted in the minibuffer.
If any errors or warnings were encountered during formatting,
they are shown in a buffer called *format-all-errors*."
(interactive)
(cl-destructuring-bind (formatter language) (format-all--probe)
(if formatter
(format-all-buffer--with formatter language)
(error "Don't know how to format %S code" major-mode))))
(interactive "p")
(let* ((language (format-all--language-id-buffer))
(chain (format-all--get-chain language)))
(when (and (not chain) prompt-p)
(let ((f-name (format-all--prompt-for-formatter language)))
(when f-name
(message "Setting formatter to %S" f-name)
(setq chain (list f-name))
(format-all--set-chain language chain))))
(unless chain (error "No formatter"))
(format-all--run-chain language chain)))

;;;###autoload
(define-minor-mode format-all-mode
Expand Down Expand Up @@ -854,11 +948,11 @@ or zero, and enabled otherwise."
:global nil
(if format-all-mode
(add-hook 'before-save-hook
'format-all-buffer--from-hook
'format-all--buffer-from-hook
nil 'local)
(remove-hook 'before-save-hook
'format-all-buffer--from-hook
'local)))
(remove-hook 'before-save-hook
'format-all--buffer-from-hook
'local)))

(provide 'format-all)

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