Re: uniq

[Stephen Berman <stephen.berman@gmx.net>]

On Fri, 3 Dec 2010 18:41:12 -0800 Tak Ota <Takaaki.Ota@am.sony.com> wrote:

> Do we have something equivalent to the next command?  I know the name
> is bad as it is not same as UNIQ(1).  It works better because sorting
> is not required.
>
> -Tak
>
> ;;
> ;; uniq
> ;;
> (defun uniq ()
>   "Omit duplicated lines."
>   (interactive)
>   (save-excursion
>     (goto-char (point-min))
>     (while (not (= (point) (point-max)))
>       (let* ((start (point))
> 	     (str (format "^%s"
> 			  (regexp-quote
> 			   (buffer-substring start
> 					     (progn (forward-line 1) (point)))))))
> 	(save-excursion
> 	  (while (re-search-forward str nil t)
> 	    (delete-region (match-beginning 0) (match-end 0))))))))

Would it be faster to avoid nested while-loops?

(defun uniq ()
  "Omit duplicated lines."
  (interactive)
  (let (lines)
    (save-excursion
      (goto-char (point-min))
      (while (not (eobp))
	(let* ((beg (line-beginning-position))
	       (end (line-end-position))
	       (line (buffer-substring beg end)))
	  (if (member line lines)
	      (delete-region beg (1+ end))
	    (push line lines)
	    (forward-line)))))))

Steve Berman