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|
;;; flymake-rust -- Flymake integration for the Rust programming language -*- lexical-binding: t; -*-
;; Copyright © 2021 Brian Cully <bjc@kublai.com>
;; Author: Brian Cully <bjc@kublai.com>
;; URL: https://github.com/bjc/nspawn-tramp
;; Keywords: flymake, rust
;; Maintainer: Brian Cully <bjc@kublai.com>
;; Version: 0.1
;; Package-Requires: ((emacs "26.1"))
;;; License:
;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Add support for the Rust programming language to Flymake.
;;
;; ## Usage
;;
;; Call ‘flymake-rust-setup’ in your Emacs initialization.
;;
;; (add-hook ’rust-mode-hook ’flymake-rust-setup)
;;
;;; Code:
(defgroup flymake-rust nil
"Flymake integration for the Rust programming language."
:prefix "flymake-rust-"
:group 'applications
:link '(url-link :tag "Github" "https://github.com/bjc/flymake-rust")
:link '(emacs-commentary-link :tag "Commentary" "flymake-rust"))
(defcustom flymake-rust-cargo-path "cargo"
"Path to cargo executable."
:type 'string
:group 'flymake-rust)
(defvar-local flymake-rust--process nil
"Flymake process associated with the current buffer.")
(defvar-local flymake-rust--parse-marker nil
"Last parse position in the current buffer.")
(defun flymake-rust--buffer-name (suffix)
"What to name the flymake buffer for ‘SUFFIX’."
(format "*flymake-rust-cargo-check %s %s*" suffix buffer-file-name))
(defmacro flymake-rust--with-proc-buf (&rest body)
"Run ‘BODY’ in the buffer for the current buffer’s Flymake process."
(declare (indent defun))
(let ((buf (gensym)))
`(when-let ((,buf (and flymake-rust--process
(process-buffer flymake-rust--process))))
(with-current-buffer ,buf
,@body))))
(defun flymake-rust--extract-error-location (hash)
"Extract file location data from ‘HASH’.
Returns a sequence of data in the form of (BYTE-START . BYTE-END)
If any data are not available, nil will be used in its place."
(let* ((spans (or (gethash "spans" hash) [])))
(mapcar (lambda (span)
(let ((byte-start (or (gethash "byte_start" span) nil))
(byte-end (or (gethash "byte_end" span) nil)))
`(,byte-start . ,byte-end)))
spans)))
(defun flymake-rust--level-to-action (level)
"Convert ‘LEVEL’ into a Flymake action."
(cond ((string= level "error") :error)
((string= level "warning") :warning)
(t :note)))
(defun flymake-rust--report-errors (source-buffer report-fn hash)
"Pull interesting things out of ‘HASH’ for ‘SOURCE-BUFFER ’and forward them to ‘REPORT-FN’."
(let ((reason (gethash "reason" hash))
(msghash (gethash "message" hash)))
(when (and (string= reason "compiler-message") msghash)
(let ((message (gethash "message" msghash))
(level (gethash "level" msghash))
(errlocs (flymake-rust--extract-error-location msghash)))
(funcall report-fn
(mapcar (lambda (errloc)
(flymake-make-diagnostic source-buffer
(car errloc) (cdr errloc)
(flymake-rust--level-to-action level)
message))
errlocs))))))
(defun flymake-rust--parse-json (source-buffer report-fn)
"Grab new JSON from ‘SOURCE-BUFFER’ and send it to ‘REPORT-FN’.
This function attempts to parse JSON data beginning at
‘flymake-rust--parse-marker’ and if successful, will update
the marker to the end of the parsed data."
(goto-char flymake-rust--parse-marker)
(while (condition-case err
(let ((parsed (json-parse-buffer)))
(set-marker flymake-rust--parse-marker (point))
(flymake-rust--report-errors source-buffer report-fn parsed)
t)
(json-parse-error nil)
(json-end-of-file nil)
(t (error err)))))
;; TODO: this blocks ‘C-g’, so it may be better to just do this in an
;; idle process.
(defun flymake-rust--filter (source-buffer report-fn proc string)
"Process ‘STRING’ as JSON from ‘PROC’ and send it to ‘REPORT-FN’ for ‘SOURCE-BUFFER’."
(flymake-rust--with-proc-buf
(let ((moving (= (point) (process-mark proc))))
(save-excursion
;; Append the latest output to the end of the previous.
(setq buffer-read-only nil)
(goto-char (process-mark proc))
(insert string)
(set-marker (process-mark proc) (point))
(setq buffer-read-only t)
(flymake-rust--parse-json source-buffer report-fn))
(when moving
(goto-char (process-mark proc))))))
(defun flymake-rust--make-filter (source-buffer report-fn)
"Create a process filter for ‘SOURCE-BUFFER’ reporting to ‘REPORT-FN’."
(lambda (proc string)
(flymake-rust--filter source-buffer report-fn proc string)))
(defun flymake-rust--cleanup ()
"Clean up and leftover processes and buffers for the current buffer."
(when (process-live-p flymake-rust--process)
(flymake-log :warning "Killing out-of-date checker process.")
(delete-process flymake-rust--process))
(mapc (lambda (suffix)
(when-let ((buf (get-buffer (flymake-rust--buffer-name suffix))))
(kill-buffer buf)))
'("stdout" "stderr")))
(defun flymake-rust--setup-proc-buf ()
"Set up stdout process buffer for scanning."
;; Save the position where output will begin so we can know where to
;; start scanning from when output is done.
(flymake-rust--with-proc-buf
(setq buffer-read-only t)
(setq flymake-rust--parse-marker (make-marker))
(set-marker flymake-rust--parse-marker (point))))
(defun flymake-rust--call (source-buffer report-fn)
"Call out to the syntax checker for ‘SOURCE-BUFFER’ and report to ‘REPORT-FN’."
(with-current-buffer source-buffer
(flymake-rust--cleanup)
(setq flymake-rust--process
(make-process :name "flymake-rust-cargo-check"
:buffer (flymake-rust--buffer-name "stdout")
:command `(,flymake-rust-cargo-path "check" "--quiet" "--message-format" "json")
:noquery nil
:filter (flymake-rust--make-filter source-buffer report-fn)
:stderr (flymake-rust--buffer-name "stderr")
:stderr nil
:file-handler t))
(flymake-rust--setup-proc-buf)))
(defun flymake-rust--backend (report-fn &rest args)
"Send Flymake diagnostics to ‘REPORT-FN’.
For the value of ‘ARGS’, see the documentation for
‘flymake-diagnostic-functions’."
(let ((rc (plist-member args :recent-changes)))
(when (or (not rc) (cadr rc))
(flymake-rust--call (current-buffer) report-fn))))
(defun flymake-rust-setup ()
"Provide Flymake support for the Rust programming language."
(add-hook 'flymake-diagnostic-functions 'flymake-rust--backend nil t))
(provide 'flymake-rust)
;;; flymake-rust.el ends here
|
