;; Tab conversion commands for Emacs 
;; Copyright (C) 1985 Richard M. Stallman. 
 
;; This file is part of GNU Emacs. 
 
;; GNU Emacs is distributed in the hope that it will be useful, 
;; but without any warranty.  No author or distributor 
;; accepts responsibility to anyone for the consequences of using it 
;; or for whether it serves any particular purpose or works at all, 
;; unless he says so in writing. 
 
;; Everyone is granted permission to copy, modify and redistribute 
;; GNU Emacs, but only under the conditions described in the 
;; document "GNU Emacs copying permission notice".   An exact copy 
;; of the document is supposed to have been given to you along with 
;; GNU Emacs so that you can know how you may redistribute it all. 
;; It should be in a file named COPYING.  Among other things, the 
;; copyright notice and this notice must be preserved on all copies. 
 
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(defun untabify (start end) (interactive) 
  "Convert all tabs in region to multiple spaces, preserving columns. 
The variable tab-width controls the action." 
  (save-excursion 
   (save-restriction 
    (narrow-to-region start end) 
    (goto-char start) 
    (while (re-search-forward "\t*" nil t) 
      (let ((column (current-column)) 
	    (indent-tabs-mode nil)) 
	(delete-region (match-beginning 0) (dot)) 
	(indent-to column)))))) 
 
(defun tabify (start end) (interactive) 
  "Convert multiple spaces in region to tabs when possible. 
A group of spaces is partially replaced by tabs 
when this can be done without changing the column they end at. 
The variable tab-width controls the action." 
  (save-excursion 
   (save-restriction 
    (narrow-to-region start end) 
    (goto-char start) 
    (while (re-search-forward "[ \t][ \t][ \t]*" nil t) 
      (let ((column (current-column)) 
	    (indent-tabs-mode t)) 
	(delete-region (match-beginning 0) (dot)) 
	(indent-to column)))))) 