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105 lines
4.1 KiB
EmacsLisp
105 lines
4.1 KiB
EmacsLisp
;;; tabify.el --- tab conversion commands for Emacs -*- lexical-binding: t -*-
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;; Copyright (C) 1985, 1994, 2001-2020 Free Software Foundation, Inc.
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;; Maintainer: emacs-devel@gnu.org
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;; Package: emacs
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Commands to optimize spaces to tabs or expand tabs to spaces in a region
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;; (`tabify' and `untabify'). The variable tab-width does the obvious.
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;;; Code:
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;;;###autoload
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(defun untabify (start end &optional _arg)
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"Convert all tabs in region to multiple spaces, preserving columns.
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If called interactively with prefix ARG, convert for the entire
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buffer.
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Called non-interactively, the region is specified by arguments
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START and END, rather than by the position of point and mark.
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The variable `tab-width' controls the spacing of tab stops."
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(interactive (if current-prefix-arg
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(list (point-min) (point-max) current-prefix-arg)
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(list (region-beginning) (region-end) nil)))
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(let ((c (current-column)))
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(save-excursion
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(save-restriction
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(narrow-to-region (point-min) end)
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(goto-char start)
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(while (search-forward "\t" nil t) ; faster than re-search
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(forward-char -1)
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(let ((tab-beg (point))
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(indent-tabs-mode nil)
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column)
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(skip-chars-forward "\t")
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(setq column (current-column))
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(delete-region tab-beg (point))
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(indent-to column)))))
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(move-to-column c)))
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(defvar tabify-regexp " [ \t]+"
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"Regexp matching whitespace that tabify should consider.
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Usually this will be \" [ \\t]+\" to match a space followed by whitespace.
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\"^\\t* [ \\t]+\" is also useful, for tabifying only initial whitespace.")
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;;;###autoload
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(defun tabify (start end &optional _arg)
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"Convert multiple spaces in region to tabs when possible.
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A group of spaces is partially replaced by tabs
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when this can be done without changing the column they end at.
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If called interactively with prefix ARG, convert for the entire
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buffer.
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Called non-interactively, the region is specified by arguments
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START and END, rather than by the position of point and mark.
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The variable `tab-width' controls the spacing of tab stops."
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(interactive (if current-prefix-arg
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(list (point-min) (point-max) current-prefix-arg)
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(list (region-beginning) (region-end) nil)))
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(save-excursion
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(save-restriction
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;; Include the beginning of the line in the narrowing
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;; since otherwise it will throw off current-column.
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(goto-char start)
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(beginning-of-line)
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(narrow-to-region (point) end)
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(goto-char start)
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(let ((indent-tabs-mode t))
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(while (re-search-forward tabify-regexp nil t)
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;; The region between (match-beginning 0) and (match-end 0) is just
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;; spacing which we want to adjust to use TABs where possible.
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(let ((end-col (current-column))
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(beg-col (save-excursion (goto-char (match-beginning 0))
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(skip-chars-forward "\t")
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(current-column))))
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(if (= (/ end-col tab-width) (/ beg-col tab-width))
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;; The spacing (after some leading TABs which we wouldn't
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;; want to touch anyway) does not straddle a TAB boundary,
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;; so it neither contains a TAB, nor will we be able to use
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;; a TAB here anyway: there's nothing to do.
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nil
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(delete-region (match-beginning 0) (point))
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(indent-to end-col))))))))
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(provide 'tabify)
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;;; tabify.el ends here
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