受够了每次向emacs粘贴xcode日志都要用keep-lines了。 (first-line-filter-mode)

(defun first-line-filter (b e l)
  (save-excursion
    (goto-char (point-min)) ;goto first line
    (let ((line (buffer-substring-no-properties (line-beginning-position) (line-end-position)))) ;;use it as pattern
      (forward-line)
      (keep-lines line (point) (point-max)))))
(define-minor-mode first-line-filter-mode "use the first line as filter whenever text insertion is happened."
  nil " *FL"
  nil (add-hook 'after-change-functions #'first-line-filter nil t))

;;之前傻乎乎地把keep-lines山寨了一遍，f**k
;; (defun first-line-filter (b e l)
;;   (save-excursion
;;     (goto-char (point-min)) ;goto first line
;;     (let ((line (buffer-substring-no-properties (line-beginning-position) (line-end-position)))) ;;use it as pattern
;;       (forward-line)
;;       (forward-line) ;process other lines
;;       (while (not (eobp))
;;         (if (string-match line (buffer-substring-no-properties (line-beginning-position) (line-end-position)))
;;             (forward-line) ;skip matched line
;;           (progn (beginning-of-line) (delete-region (point) ;kill unmatched like grep
;;                                                     (min (1+ (line-end-position)) (point-max)))))))))