;;; tabify.el --- tab conversion commands for Emacs
-;; Copyright (C) 1985, 1994 Free Software Foundation, Inc.
+;; Copyright (C) 1985, 1994, 2001, 2002, 2003, 2004,
+;; 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
;; Maintainer: FSF
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation; either version 2, or (at your option)
-;; any later version.
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs; see the file COPYING. If not, write to the
-;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-;; Boston, MA 02110-1301, USA.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
(delete-region tab-beg (point))
(indent-to column))))))
-(defvar tabify-regexp "[ \t][ \t]+"
+(defvar tabify-regexp " [ \t]+"
"Regexp matching whitespace that tabify should consider.
-Usually this will be \"[ \\t][ \\t]+\" to match two or more spaces or tabs.
-\"^[ \\t]+\" is also useful, for tabifying only initial whitespace.")
+Usually this will be \" [ \\t]+\" to match a space followed by whitespace.
+\"^\\t* [ \\t]+\" is also useful, for tabifying only initial whitespace.")
;;;###autoload
(defun tabify (start end)
(beginning-of-line)
(narrow-to-region (point) end)
(goto-char start)
- (while (re-search-forward tabify-regexp nil t)
- (let ((column (current-column))
- (indent-tabs-mode t))
- (delete-region (match-beginning 0) (point))
- (indent-to column))))))
+ (let ((indent-tabs-mode t))
+ (while (re-search-forward tabify-regexp nil t)
+ ;; The region between (match-beginning 0) and (match-end 0) is just
+ ;; spacing which we want to adjust to use TABs where possible.
+ (let ((end-col (current-column))
+ (beg-col (save-excursion (goto-char (match-beginning 0))
+ (skip-chars-forward "\t")
+ (current-column))))
+ (if (= (/ end-col tab-width) (/ beg-col tab-width))
+ ;; The spacing (after some leading TABs which we wouldn't
+ ;; want to touch anyway) does not straddle a TAB boundary,
+ ;; so it neither contains a TAB, nor will we be able to use
+ ;; a TAB here anyway: there's nothing to do.
+ nil
+ (delete-region (match-beginning 0) (point))
+ (indent-to end-col))))))))
(provide 'tabify)
-;;; arch-tag: c83893b1-e0cc-4e57-8a09-73fd03466416
+;; arch-tag: c83893b1-e0cc-4e57-8a09-73fd03466416
;;; tabify.el ends here