Emacs(Elisp): To integrate indent style, delete existing whitespaces before indent-for-tab-command. indent-for-tab-commandの前に存在する行頭ホワイトスペースを削除することでインデントスタイルを統一する

defadvice-indent-for-tab-command.el

;; defadvice-indent-for-tab-command
;; gist-description: Emacs(Elisp): To integrate indent style, delete existing whitespaces before indent-for-tab-command. indent-for-tab-commandの前に存在する行頭ホワイトスペースを削除することでインデントスタイルを統一する
;; gist-id: 604173d11ff376036635fd4811df6abb
;; gist-name: defadvice-indent-for-tab-command.el
;; gist-private: nil

(defadvice indent-for-tab-command (around advise-indent-for-tab-command activate)
  "To integrate indent style, delete existing whitespaces before indentation."
  (let (beg
        end
        (end-line nil))
    (cond
     ((use-region-p)
      (setq beg (region-beginning)
            end (region-end)
            end-line (line-number-at-pos end)))
     (t
      (beginning-of-line)
      (setq beg (point))
      (end-of-line)
      (setq end (point))))

    (perform-replace "^[\t ]+" "" nil t nil nil nil beg end)
    (goto-char beg)
    (set-mark-command nil)
    (goto-char end)

    ad-do-it

    (when end-line (goto-line (- end-line 1))) ;; why should i have to do minus?
    (back-to-indentation)))