;;; -*- lexical-binding: t -*-

(defvar caps-lock-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map [remap self-insert-command] 'upcased-self-insert)
    map))

(define-minor-mode caps-lock-mode
  "Caps lock minor mode."
  nil " CLK" caps-lock-mode-map)

(defun upcased-self-insert (arg)
  "Insert an uppercase version of the input, unless in a comment or string"
  (interactive "p")
  (let* ((syn (syntax-ppss))
         (comment-or-string (or (nth 4 syn) (nth 3 syn)))
         (last-command-event (if (and (not comment-or-string)
                                      (characterp last-command-event))
                                 (upcase last-command-event)
                               last-command-event)))
    (self-insert-command arg)))

(provide 'caps-lock-mode)