Emacs(Elisp): duplicate region or line. if same command repeated, then duplicate sate strings. 選択範囲がある場合は選択範囲を、選択範囲がない場合は、行を複製します。繰り返した場合、同じ文字列を複製し続けます。

duplicate-region-or-line.el

;;; 行／選択範囲の複製 (cmd+d)
;; gist-description: Emacs(Elisp): duplicate region or line.  if same command repeated, then duplicate sate strings.  選択範囲がある場合は選択範囲を、選択範囲がない場合は、行を複製します。繰り返した場合、同じ文字列を複製し続けます。
;; gist-id: 297fe973cde66b384fa1
;; gist-name: duplicate-region-or-line.el
;; gist-private: nil

(defvar previous-duplicate-region-or-line nil)
(defvar previous-duplicate-region-or-line-was-line nil)

(defun duplicate-region-or-line ()
  "Duplicate the region if active, otherwise duplicate the current line."
  (interactive)
  (let* ((region-active (region-active-p))
         (is-repeat (eq last-command this-command))
         (beg (if region-active (region-beginning) (line-beginning-position)))
         (end (if region-active (region-end) (line-end-position)))
         (strings (buffer-substring-no-properties beg end))
         (is-line (if is-repeat
                      previous-duplicate-region-or-line-was-line
                    (not region-active))))
    ;; Adjust strings for line duplication
    (when is-line
      (setq strings (concat "\n" strings))
      (end-of-line))
    ;; Insert the duplicated text
    (if is-repeat
        (insert previous-duplicate-region-or-line)
      (insert strings)
      (setq previous-duplicate-region-or-line strings))
    ;; Store whether it was a line duplication
    (setq previous-duplicate-region-or-line-was-line is-line)))

(global-set-key (kbd "s-d") 'duplicate-region-or-line)