Emacs: Cycle Hyphen/Lowline/Space

Here's a command that cycles hypen/lowline/space for word under cursor. (lowline is also known as underscore) (the command was known as xah-cycle-hyphen-underscore-space before 2021-08-09)

(defun xah-cycle-hyphen-lowline-space ( &optional @begin @end )
  "Cycle hyphen/lowline/space chars in selection or inside quote/bracket or line, in that order.
When this command is called, pressing t will repeat it. Press other key to exit.
The region to work on is by this order:
 1. if there is a selection, use that.
 2. If cursor is string quote or any type of bracket, and is within current line, work on that region.
 3. else, work on current line.
URL `http://ergoemacs.org/emacs/elisp_change_space-hyphen_underscore.html'
Version 2019-02-12 2021-08-09"
  (interactive)
  ;; this function sets a property 'state. Possible values are 0 to length of $charArray.
  (let ($p1 $p2)
    (if (and @begin @end)
        (setq $p1 @begin $p2 @end)
      (if (use-region-p)
          (setq $p1 (region-beginning) $p2 (region-end))
        (if (nth 3 (syntax-ppss))
            (save-excursion
              (skip-chars-backward "^\"")
              (setq $p1 (point))
              (skip-chars-forward "^\"")
              (setq $p2 (point)))
          (let (($skipChars "^\"<>(){}[]“”‘’‹›«»「」『』【】〖〗《》〈〉〔〕（）"))
            (skip-chars-backward $skipChars (line-beginning-position))
            (setq $p1 (point))
            (skip-chars-forward $skipChars (line-end-position))
            (setq $p2 (point))
            (set-mark $p1)))))
    (let ( $charArray $length $regionWasActive-p $nowState $changeTo)
      (setq $charArray ["-" "_" " "])
      (setq $length (length $charArray))
      (setq $regionWasActive-p (region-active-p))
      (setq $nowState (if (eq last-command this-command) (get 'xah-cycle-hyphen-lowline-space 'state) 0 ))
      (setq $changeTo (elt $charArray $nowState))
      (save-excursion
        (save-restriction
          (narrow-to-region $p1 $p2)
          (goto-char (point-min))
          (while (re-search-forward (elt $charArray (% (+ $nowState 2) $length)) (point-max) "move")
            (replace-match $changeTo t t))))
      (when (or (string-equal $changeTo " ") $regionWasActive-p)
        (goto-char $p2)
        (set-mark $p1)
        (setq deactivate-mark nil))
      (put 'xah-cycle-hyphen-lowline-space 'state (% (+ $nowState 1) $length))))
  (set-transient-map (let (($kmap (make-sparse-keymap))) (define-key $kmap (kbd "t") 'xah-cycle-hyphen-lowline-space ) $kmap)))

Dired Rename File from Space to Hyphen/Lowline

Emacs: Rename File, Space to Hyphen/Lowline