lisp/tabify.el

   1 ;;; tabify.el --- tab conversion commands for Emacs
   2
   3 ;; Copyright (C) 1985, 1994, 2002, 2003, 2004,
   4 ;;   2005, 2006 Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23 ;; Boston, MA 02110-1301, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; Commands to optimize spaces to tabs or expand tabs to spaces in a region
  28 ;; (`tabify' and `untabify').  The variable tab-width does the obvious.
  29
  30 ;;; Code:
  31
  32 ;;;###autoload
  33 (defun untabify (start end)
  34   "Convert all tabs in region to multiple spaces, preserving columns.
  35 Called non-interactively, the region is specified by arguments
  36 START and END, rather than by the position of point and mark.
  37 The variable `tab-width' controls the spacing of tab stops."
  38   (interactive "r")
  39   (save-excursion
  40     (save-restriction
  41       (narrow-to-region (point-min) end)
  42       (goto-char start)
  43       (while (search-forward "\t" nil t)        ; faster than re-search
  44         (forward-char -1)
  45         (let ((tab-beg (point))
  46               (indent-tabs-mode nil)
  47               column)
  48           (skip-chars-forward "\t")
  49           (setq column (current-column))
  50           (delete-region tab-beg (point))
  51           (indent-to column))))))
  52
  53 (defvar tabify-regexp "[ \t][ \t]+"
  54   "Regexp matching whitespace that tabify should consider.
  55 Usually this will be \"[ \\t][ \\t]+\" to match two or more spaces or tabs.
  56 \"^[ \\t]+\" is also useful, for tabifying only initial whitespace.")
  57
  58 ;;;###autoload
  59 (defun tabify (start end)
  60   "Convert multiple spaces in region to tabs when possible.
  61 A group of spaces is partially replaced by tabs
  62 when this can be done without changing the column they end at.
  63 Called non-interactively, the region is specified by arguments
  64 START and END, rather than by the position of point and mark.
  65 The variable `tab-width' controls the spacing of tab stops."
  66   (interactive "r")
  67   (save-excursion
  68     (save-restriction
  69       ;; Include the beginning of the line in the narrowing
  70       ;; since otherwise it will throw off current-column.
  71       (goto-char start)
  72       (beginning-of-line)
  73       (narrow-to-region (point) end)
  74       (goto-char start)
  75       (while (re-search-forward tabify-regexp nil t)
  76         (let ((column (current-column))
  77               (indent-tabs-mode t))
  78           (delete-region (match-beginning 0) (point))
  79           (indent-to column))))))
  80
  81 (provide 'tabify)
  82
  83 ;;; arch-tag: c83893b1-e0cc-4e57-8a09-73fd03466416
  84 ;;; tabify.el ends here