Add rubocop and standardrb formatters for Ruby

README.md

@@ -57,7 +57,7 @@ Supported languages
 * **Python** ([*black*](https://github.com/ambv/black), [*yapf*](https://github.com/google/yapf))
 * **R** ([*styler*](https://github.com/r-lib/styler))
 * **Reason** ([*bsrefmt*](https://github.com/glennsl/bs-refmt))
-* **Ruby** ([*rufo*](https://github.com/ruby-formatter/rufo))
+* **Ruby** ([*rubocop*](https://github.com/rubocop-hq/rubocop), [*rufo*](https://github.com/ruby-formatter/rufo), [*standardrb*](https://github.com/testdouble/standard))
 * **Rust** ([*rustfmt*](https://github.com/rust-lang-nursery/rustfmt))
 * **Scala** ([*scalafmt*](https://github.com/scalameta/scalafmt))
 * **Shell script** ([*beautysh*](https://github.com/lovesegfault/beautysh), [*shfmt*](https://github.com/mvdan/sh))

format-all.el

@@ -63,7 +63,7 @@
 ;; - Python (black, yapf)
 ;; - R (styler)
 ;; - Reason (bsrefmt)
-;; - Ruby (rufo)
+;; - Ruby (rubocop, rufo, standardrb)
 ;; - Rust (rustfmt)
 ;; - Scala (scalafmt)
 ;; - Shell script (beautysh, shfmt)
@@ -347,6 +347,53 @@ If ARGS are given, those are arguments to EXECUTABLE.  They don't
 need to be shell-quoted."
   (apply 'format-all--buffer-hard nil nil nil executable args))
 
+(defun format-all--ruby-gem-bundled-p (gem-name)
+  "Internal helper function to check if GEM-NAME is listed in the current project's Gemfile.lock."
+  (let* ((lockfile "Gemfile.lock")
+         (dir (locate-dominating-file (buffer-file-name) lockfile)))
+    (and dir
+         (not
+          (string=
+           ""
+           (shell-command-to-string
+            (format "grep -e %s -- %s 2>/dev/null"
+                    (shell-quote-argument
+                     (format "^    %s " gem-name))
+                    (shell-quote-argument
+                     (expand-file-name lockfile dir)))))))))
+
+(defun format-all--buffer-hard-ruby
+    (gem-name ok-statuses error-regexp root-files executable &rest args)
+  "Internal helper function to implement ruby based formatters.
+
+GEM-NAME is the name of a Ruby gem required to run EXECUTABLE.
+
+For OK-STATUSES, ERROR-REGEXP, ROOT-FILES, EXECUTABLE and ARGS, see `format-all--buffer-hard'."
+  (let* ((error-regexp
+          (apply #'regexp-or
+                 "Bundler::GemNotFound"
+                 (concat (regexp-or "bundle" (regexp-quote executable))
+                         ": command not found")
+                 (if error-regexp (list error-regexp))))
+         (command-args
+          (append (if (format-all--ruby-gem-bundled-p gem-name)
+                      '("bundle" "exec"))
+                  (cons executable args)))
+         (command-args
+          ;; This tweak will eventually be removed after rubocop with
+          ;; --stderr has been released and a sufficient amount of
+          ;; time has passed.
+          (if (member executable '("rubocop" "standardrb"))
+              (list
+               "bash" "-eo" "pipefail" "-c"
+               (format "%s | ruby -ne 'print unless 1../^={20}$/'"
+                       (mapconcat #'shell-quote-argument command-args " ")))
+            command-args)))
+    (format-all--buffer-hard
+     ok-statuses error-regexp root-files
+     (car command-args)
+     (cdr command-args))))
+
 (defvar format-all--executable-table (make-hash-table)
   "Internal table of formatter executable names for format-all.")
 
@@ -693,12 +740,36 @@ Consult the existing formatters for examples of BODY."
   (:install "gem install rufo")
   (:languages "Ruby")
   (:format
-   (format-all--buffer-easy
-    executable
+   (format-all--buffer-hard-ruby
+    "rufo" nil nil nil
+    "rufo"
     "--simple-exit"
     (when (buffer-file-name)
       (list "--filename" (buffer-file-name))))))
 
+(define-format-all-formatter rubocop
+    (:executable "rubocop")
+    (:install "gem install rubocop")
+    (:languages "Ruby")
+    (:format
+     (format-all--buffer-hard-ruby
+      "rubocop" '(0 1) nil nil
+      "rubocop"
+      "--auto-format"
+      "--format" "quiet"
+      "--stdin" (or (buffer-file-name) (buffer-name)))))
+
+(define-format-all-formatter standardrb
+    (:executable "standardrb")
+    (:install "gem install standard")
+    (:languages "Ruby")
+    (:format
+     (format-all--buffer-hard-ruby
+      "standard" '(0 1) nil nil
+      "standardrb"
+      "--auto-format"
+      "--stdin" (or (buffer-file-name) (buffer-name)))))
+
 (define-format-all-formatter rustfmt
   (:executable "rustfmt")
   (:install "rustup component add rustfmt")