feat(vendor/clang-format): add custom reformatter-based clang-format package

There is a clang-format package in MELPA, but I believe a
reformatter-based solution works better. Hence I've made my own,
somewhat like a package, and simply thrown it into the vendor directory.

vendor/clang-format/clang-format.el

@@ -0,0 +1,84 @@
+;;; clang-format.el --- Format files with clang-format.
+
+;; Copyright (C) 2022 Jim Myhrberg
+
+;; Author: Jim Myhrberg <contact@jimeh.me>
+;; Keywords: formatting, tools
+;; Package-Requires: ((emacs "25.1") (reformatter "0.6"))
+;; Package-Version: 0.0.1
+
+(require 'reformatter)
+
+(reformatter-define clang-format
+  :program "clang-format"
+  :args '("-style=file" "--assume-filename=%s")
+  :lighter " TF")
+
+(require 'reformatter)
+
+(defgroup clang-format nil
+  "Format buffers with clang-format."
+  :group 'tools)
+
+(defcustom clang-format-executable "clang-format"
+  "Name/path of the clang-format executable."
+  :group 'clang-format
+  :type 'string)
+
+(defcustom clang-format-style nil
+  "Style argument to pass to clang-format.
+By default clang-format will load the style configuration from
+a file named .clang-format located in one of the parent directories
+of the buffer."
+  :group 'clang-format
+  :type '(choice (string) (const nil))
+  :safe #'stringp)
+(make-variable-buffer-local 'clang-format-style)
+
+(defcustom clang-format-fallback-style "none"
+  "Fallback style to pass to clang-format.
+This style will be used if clang-format-style is set to \"file\"
+and no .clang-format is found in the directory of the buffer or
+one of parent directories. Set to \"none\" to disable formatting
+in such buffers."
+  :group 'clang-format
+  :type 'string
+  :safe #'stringp)
+(make-variable-buffer-local 'clang-format-fallback-style)
+
+(defcustom clang-format-sort-includes t
+  "Override the include sorting behavior.
+As determined by the SortIncludes style flag."
+  :group 'clang-format
+  :type 'boolean)
+(make-variable-buffer-local 'clang-format-sort-includes)
+
+(defcustom clang-format-extra-args nil
+  "Extra arguments to pass to clang-format."
+  :group 'clang-format
+  :type '(repeat string))
+(make-variable-buffer-local 'clang-format-extra-args)
+
+(defun clang-format--make-args ()
+  "Helper to build the argument list for jq."
+  (let* ((region-active (use-region-p))
+         (start (bufferpos-to-filepos (region-beginning)))
+         (end (bufferpos-to-filepos (region-end)))
+         (length (abs (- end start))))
+    (append
+     (when buffer-file-name `("--assume-filename" ,buffer-file-name))
+     (when clang-format-sort-includes '("--sort-includes"))
+     (when region-active `("--offset" ,(number-to-string start)
+                           "--length" ,(number-to-string length)))
+     clang-format-extra-args)))
+
+;;;###autoload (autoload 'clang-format-buffer "clang-format" nil t)
+;;;###autoload (autoload 'clang-format-region "clang-format" nil t)
+;;;###autoload (autoload 'clang-format-on-save-mode "clang-format" nil t)
+(reformatter-define clang-format
+  :program clang-format-executable
+  :args (clang-format--make-args)
+  :lighter "CLFmt"
+  :group 'clang-format)
+
+(provide 'clang-format)