1 ;;; longlines.el --- automatically wrap long lines
3 ;; Copyright (C) 2000, 2001, 2004, 2005 by Free Software Foundation, Inc.
5 ;; Authors: Kai Grossjohann <Kai.Grossjohann@CS.Uni-Dortmund.DE>
6 ;; Alex Schroeder <alex@gnu.org>
7 ;; Chong Yidong <cyd@stupidchicken.com>
8 ;; Maintainer: Chong Yidong <cyd@stupidchicken.com>
9 ;; Keywords: convenience
11 ;; This file is part of GNU Emacs.
13 ;; GNU Emacs is free software; you can redistribute it and/or modify
14 ;; it under the terms of the GNU General Public License as published by
15 ;; the Free Software Foundation; either version 2, or (at your option)
18 ;; GNU Emacs is distributed in the hope that it will be useful,
19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ;; GNU General Public License for more details.
23 ;; You should have received a copy of the GNU General Public License
24 ;; along with GNU Emacs; see the file COPYING. If not, write to the
25 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
26 ;; Boston, MA 02111-1307, USA.
30 ;; Some text editors save text files with long lines, and they
31 ;; automatically break these lines at whitespace, without actually
32 ;; inserting any newline characters. When doing `M-q' in Emacs, you
33 ;; are inserting newline characters. Longlines mode provides a file
34 ;; format which wraps the long lines when reading a file and unwraps
35 ;; the lines when saving the file. It can also wrap and unwrap
36 ;; automatically as editing takes place.
38 ;; Special thanks to Rod Smith for many useful bug reports.
44 (defgroup longlines nil
45 "Automatic wrapping of long lines when loading files."
48 (defcustom longlines-auto-wrap t
49 "*Non-nil means long lines are automatically wrapped after each command.
50 Otherwise, you can perform filling using `fill-paragraph' or
51 `auto-fill-mode'. In any case, the soft newlines will be removed
52 when the file is saved to disk."
56 (defcustom longlines-wrap-follows-window-size nil
57 "*Non-nil means wrapping and filling happen at the edge of the window.
58 Otherwise, `fill-column' is used, regardless of the window size. This
59 does not work well when the buffer is displayed in multiple windows
60 with differing widths."
64 (defcustom longlines-show-hard-newlines nil
65 "*Non-nil means each hard newline is marked with a symbol.
66 You can also enable the display temporarily, using the command
67 `longlines-show-hard-newlines'"
71 (defcustom longlines-show-effect (propertize "|\n" 'face 'escape-glyph)
72 "*A string to display when showing hard newlines.
73 This is used when `longlines-show-hard-newlines' is on."
79 (defvar longlines-wrap-beg nil)
80 (defvar longlines-wrap-end nil)
81 (defvar longlines-wrap-point nil)
82 (defvar longlines-showing nil)
84 (make-variable-buffer-local 'longlines-wrap-beg)
85 (make-variable-buffer-local 'longlines-wrap-end)
86 (make-variable-buffer-local 'longlines-wrap-point)
87 (make-variable-buffer-local 'longlines-showing)
92 (define-minor-mode longlines-mode
93 "Toggle Long Lines mode.
94 In Long Lines mode, long lines are wrapped if they extend beyond
95 `fill-column'. The soft newlines used for line wrapping will not
96 show up when the text is yanked or saved to disk.
98 If `longlines-auto-wrap' is non-nil, lines are automatically
99 wrapped whenever the buffer is changed. You can always call
100 `fill-paragraph' to fill individual paragraphs.
102 If `longlines-show-hard-newlines' is non-nil, hard newlines will
103 be marked by a symbol."
104 :group 'longlines :lighter " ll"
106 ;; Turn on longlines mode
108 (use-hard-newlines 1 'never)
109 (set (make-local-variable 'require-final-newline) nil)
110 (add-to-list 'buffer-file-format 'longlines)
111 (add-hook 'change-major-mode-hook 'longlines-mode-off nil t)
112 (make-local-variable 'buffer-substring-filters)
113 (add-to-list 'buffer-substring-filters 'longlines-encode-string)
114 (when longlines-wrap-follows-window-size
115 (set (make-local-variable 'fill-column)
116 (- (window-width) window-min-width))
117 (add-hook 'window-configuration-change-hook
118 'longlines-window-change-function nil t))
119 (let ((buffer-undo-list t)
120 (mod (buffer-modified-p)))
121 ;; Turning off undo is OK since (spaces + newlines) is
122 ;; conserved, except for a corner case in
123 ;; longlines-wrap-lines that we'll never encounter from here
124 (longlines-decode-region (point-min) (point-max))
125 (longlines-wrap-region (point-min) (point-max))
126 (set-buffer-modified-p mod))
127 (when (and longlines-show-hard-newlines
128 (not longlines-showing))
129 (longlines-show-hard-newlines))
130 (when longlines-auto-wrap
132 (add-hook 'after-change-functions
133 'longlines-after-change-function nil t)
134 (add-hook 'post-command-hook
135 'longlines-post-command-function nil t)))
136 ;; Turn off longlines mode
137 (setq buffer-file-format (delete 'longlines buffer-file-format))
138 (if longlines-showing
139 (longlines-unshow-hard-newlines))
140 (let ((buffer-undo-list t))
141 (longlines-encode-region (point-min) (point-max)))
142 (remove-hook 'change-major-mode-hook 'longlines-mode-off t)
143 (remove-hook 'before-kill-functions 'longlines-encode-region t)
144 (remove-hook 'after-change-functions 'longlines-after-change-function t)
145 (remove-hook 'post-command-hook 'longlines-post-command-function t)
146 (remove-hook 'window-configuration-change-hook
147 'longlines-window-change-function t)
148 (kill-local-variable 'fill-column)))
150 (defun longlines-mode-off ()
151 "Turn off longlines mode.
152 This function exists to be called by `change-major-mode-hook' when the
156 ;; Showing the effect of hard newlines in the buffer
158 (defface longlines-visible-face
159 '((t (:background "red")))
160 "Face used to make hard newlines visible in `longlines-mode'.")
162 (defun longlines-show-hard-newlines (&optional arg)
163 "Make hard newlines visible by adding a face.
164 With optional argument ARG, make the hard newlines invisible again."
166 (let ((buffer-undo-list t)
167 (mod (buffer-modified-p)))
169 (longlines-unshow-hard-newlines)
170 (setq longlines-showing t)
171 (longlines-show-region (point-min) (point-max)))
172 (set-buffer-modified-p mod)))
174 (defun longlines-show-region (beg end)
175 "Make hard newlines between BEG and END visible."
176 (let* ((pmin (min beg end))
178 (pos (text-property-any pmin pmax 'hard t)))
180 (put-text-property pos (1+ pos) 'display
181 (copy-sequence longlines-show-effect))
182 (setq pos (text-property-any (1+ pos) pmax 'hard t)))))
184 (defun longlines-unshow-hard-newlines ()
185 "Make hard newlines invisible again."
187 (setq longlines-showing nil)
188 (let ((pos (text-property-any (point-min) (point-max) 'hard t)))
190 (remove-text-properties pos (1+ pos) '(display))
191 (setq pos (text-property-any (1+ pos) (point-max) 'hard t)))))
193 ;; Wrapping the paragraphs.
195 (defun longlines-wrap-region (beg end)
196 "Wrap each successive line, starting with the line before BEG.
197 Stop when we reach lines after END that don't need wrapping, or the
199 (setq longlines-wrap-point (point))
202 ;; Two successful longlines-wrap-line's in a row mean successive
203 ;; lines don't need wrapping.
204 (while (null (and (longlines-wrap-line)
206 (and (>= (point) end)
207 (longlines-wrap-line))))))
208 (goto-char longlines-wrap-point))
210 (defun longlines-wrap-line ()
211 "If the current line needs to be wrapped, wrap it and return nil.
212 If wrapping is performed, point remains on the line. If the line does
213 not need to be wrapped, move point to the next line and return t."
214 (if (longlines-set-breakpoint)
215 (progn (backward-char 1)
219 (if (longlines-merge-lines-p)
222 ;; After certain commands (e.g. kill-line), there may be two
223 ;; successive soft newlines in the buffer. In this case, we
224 ;; replace these two newlines by a single space. Unfortunately,
225 ;; this breaks the conservation of (spaces + newlines), so we
226 ;; have to fiddle with longlines-wrap-point.
227 (if (or (bolp) (eolp))
228 (if (> longlines-wrap-point (point))
229 (setq longlines-wrap-point
230 (1- longlines-wrap-point)))
236 (defun longlines-set-breakpoint ()
237 "Place point where we should break the current line, and return t.
238 If the line should not be broken, return nil; point remains on the
240 (move-to-column fill-column)
241 (if (and (re-search-forward "[^ ]" (line-end-position) 1)
242 (> (current-column) fill-column))
243 ;; This line is too long. Can we break it?
244 (or (longlines-find-break-backward)
245 (progn (move-to-column fill-column)
246 (longlines-find-break-forward)))))
248 (defun longlines-find-break-backward ()
249 "Move point backward to the first available breakpoint and return t.
250 If no breakpoint is found, return nil."
251 (and (search-backward " " (line-beginning-position) 1)
253 (skip-chars-backward " " (line-beginning-position))
255 (progn (forward-char 1)
256 (if (and fill-nobreak-predicate
257 (run-hook-with-args-until-success
258 'fill-nobreak-predicate))
259 (progn (skip-chars-backward " " (line-beginning-position))
260 (longlines-find-break-backward))
263 (defun longlines-find-break-forward ()
264 "Move point forward to the first available breakpoint and return t.
265 If no break point is found, return nil."
266 (and (search-forward " " (line-end-position) 1)
267 (progn (skip-chars-forward " " (line-end-position))
269 (if (and fill-nobreak-predicate
270 (run-hook-with-args-until-success
271 'fill-nobreak-predicate))
272 (longlines-find-break-forward)
275 (defun longlines-merge-lines-p ()
276 "Return t if part of the next line can fit onto the current line.
277 Otherwise, return nil. Text cannot be moved across hard newlines."
281 (null (get-text-property (point) 'hard))
282 (let ((space (- fill-column (current-column))))
284 (if (eq (char-after) ? )
285 t ; We can always merge some spaces
286 (<= (if (search-forward " " (line-end-position) 1)
288 (1+ (current-column)))
291 (defun longlines-decode-region (beg end)
292 "Turn all newlines between BEG and END into hard newlines."
294 (goto-char (min beg end))
295 (while (search-forward "\n" (max beg end) t)
296 (set-hard-newline-properties
297 (match-beginning 0) (match-end 0)))))
299 (defun longlines-encode-region (beg end &optional buffer)
300 "Replace each soft newline between BEG and END with exactly one space.
301 Hard newlines are left intact. The optional argument BUFFER exists for
302 compatibility with `format-alist', and is ignored."
304 (let ((mod (buffer-modified-p)))
305 (goto-char (min beg end))
306 (while (search-forward "\n" (max (max beg end)) t)
307 (unless (get-text-property (match-beginning 0) 'hard)
308 (replace-match " ")))
309 (set-buffer-modified-p mod)
312 (defun longlines-encode-string (string)
313 "Return a copy of STRING with each soft newline replaced by a space.
314 Hard newlines are left intact."
315 (let* ((str (copy-sequence string))
316 (pos (string-match "\n" str)))
318 (if (null (get-text-property pos 'hard str))
320 (setq pos (string-match "\n" str (1+ pos))))
325 (defun longlines-auto-wrap (&optional arg)
326 "Turn on automatic line wrapping, and wrap the entire buffer.
327 With optional argument ARG, turn off line wrapping."
329 (remove-hook 'after-change-functions 'longlines-after-change-function t)
330 (remove-hook 'post-command-hook 'longlines-post-command-function t)
332 (progn (setq longlines-auto-wrap nil)
333 (message "Auto wrap disabled."))
334 (setq longlines-auto-wrap t)
335 (add-hook 'after-change-functions
336 'longlines-after-change-function nil t)
337 (add-hook 'post-command-hook
338 'longlines-post-command-function nil t)
339 (let ((mod (buffer-modified-p)))
340 (longlines-wrap-region (point-min) (point-max))
341 (set-buffer-modified-p mod))
342 (message "Auto wrap enabled.")))
344 (defun longlines-after-change-function (beg end len)
345 "Update `longlines-wrap-beg' and `longlines-wrap-end'.
346 This is called by `after-change-functions' to keep track of the region
348 (unless undo-in-progress
349 (setq longlines-wrap-beg
350 (if longlines-wrap-beg (min longlines-wrap-beg beg) beg))
351 (setq longlines-wrap-end
352 (if longlines-wrap-end (max longlines-wrap-end end) end))))
354 (defun longlines-post-command-function ()
355 "Perform line wrapping on the parts of the buffer that have changed.
356 This is called by `post-command-hook' after each command."
357 (when longlines-wrap-beg
358 (cond ((or (eq this-command 'yank)
359 (eq this-command 'yank-pop))
360 (longlines-decode-region (point) (mark t))
361 (if longlines-showing
362 (longlines-show-region (point) (mark t))))
363 ((and (eq this-command 'newline) longlines-showing)
365 (if (search-backward "\n" nil t)
366 (longlines-show-region
367 (match-beginning 0) (match-end 0))))))
368 (unless (or (eq this-command 'fill-paragraph)
369 (eq this-command 'fill-region))
370 (longlines-wrap-region longlines-wrap-beg longlines-wrap-end))
371 (setq longlines-wrap-beg nil)
372 (setq longlines-wrap-end nil)))
374 (defun longlines-window-change-function ()
375 "Re-wrap the buffer if the window width has changed.
376 This is called by `window-size-change-functions'."
377 (when (/= fill-column (- (window-width) window-min-width))
378 (setq fill-column (- (window-width) window-min-width))
379 (let ((mod (buffer-modified-p)))
380 (longlines-wrap-region (point-min) (point-max))
381 (set-buffer-modified-p mod))))
383 ;; Loading and saving
387 (list 'longlines "Automatically wrap long lines." nil
388 'longlines-decode-region 'longlines-encode-region t nil))
392 ;; arch-tag: 3489d225-5506-47b9-8659-d8807b77c624
393 ;;; longlines.el ends here