Emacs のバッファに対して cdif を実行する関数。本当は、コマンドの実行にした場合のエラー処理を入れたいんだが、やり方がわからない。失敗したら undo してください。

cdif.el

;;; cdif.el --- cdif and ansi-color interface

;;; Code:

(autoload 'ansi-color-apply-on-region "ansi-color" nil t)

(defun cdif-buffer (&optional prefix)
  "Execute cdif command on current buffer and apply ansi-color."
  (interactive "P")
  (if prefix
      (cdif-region (region-beginning) (region-end))
    (cdif-region (point-min) (point-max))))

(defun cdif-region (begin end)
  "Execute cdif command on region and apply ansi-color."
  (interactive "r")
  (let ((opoint (point))
	(modified (buffer-modified-p)))
      (set-mark end)
      (goto-char begin)
      ;; shell-command-on-region returns exit status 1 for both successful
      ;; execution and command-not-found failure, and can't tell which.
      (shell-command-on-region begin end "cdif --nocc --no256" t t nil t)
      (message "applying ansi-color. can take a while.")
      (ansi-color-apply-on-region (region-beginning) (region-end))
      (message "done.")
      ;; save-excursion doesn't recover the point. why?
      (goto-char opoint)
      (set-buffer-modified-p modified)))