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1 ;;; indent.el --- indentation commands for Emacs
3 ;; Copyright (C) 1985, 1995, 2001 Free Software Foundation, Inc.
5 ;; Maintainer: FSF
7 ;; This file is part of GNU Emacs.
9 ;; GNU Emacs is free software; you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation; either version 2, or (at your option)
12 ;; any later version.
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs; see the file COPYING. If not, write to the
21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
22 ;; Boston, MA 02111-1307, USA.
24 ;;; Commentary:
26 ;; Commands for making and changing indentation in text. These are
27 ;; described in the Emacs manual.
29 ;;; Code:
31 (defgroup indent nil
32 "Indentation commands"
33 :group 'editing)
35 (defcustom standard-indent 4
36 "*Default number of columns for margin-changing functions to indent."
37 :group 'indent
38 :type 'integer)
40 (defvar indent-line-function 'indent-relative
41 "Function to indent the current line.
42 This function will be called with no arguments.
43 If it is called somewhere where auto-indentation cannot be done
44 \(f.ex. inside a string), the function should simply return `noindent'.
45 Setting this function is all you need to make TAB indent appropriately.
46 Don't rebind TAB unless you really need to.")
48 (defcustom tab-always-indent t
49 "*Controls the operation of the TAB key.
50 If t, hitting TAB always just indents the current line.
51 If nil, hitting TAB indents the current line if point is at the left margin
52 or in the line's indentation, otherwise it insert a \"real\" tab character."
53 :group 'indent
54 :type '(choice (const nil) (const t) (const always)))
56 (defun indent-according-to-mode ()
57 "Indent line in proper way for current major mode.
58 The buffer-local variable `indent-line-function' determines how to do this,
59 but the functions `indent-relative' and `indent-relative-maybe' are
60 special; we don't actually use them here."
61 (interactive)
62 (if (memq indent-line-function
63 '(indent-relative indent-relative-maybe))
64 ;; These functions are used for tabbing, but can't be used for
65 ;; indenting. Replace with something ad-hoc.
66 (let ((column (save-excursion
67 (beginning-of-line)
68 (skip-chars-backward "\n \t")
69 (beginning-of-line)
70 (current-indentation))))
71 (if (<= (current-column) (current-indentation))
72 (indent-line-to column)
73 (save-excursion (indent-line-to column))))
74 ;; The normal case.
75 (funcall indent-line-function)))
77 (defun indent-for-tab-command (&optional arg)
78 "Indent line in proper way for current major mode or insert a tab.
79 Depending on `tab-always-indent', either insert a tab or indent.
80 If initial point was within line's indentation, position after
81 the indentation. Else stay at same point in text.
82 The function actually called to indent is determined by the value of
83 `indent-line-function'."
84 (interactive "P")
85 (cond
86 ((or ;; indent-to-left-margin is only meant for indenting,
87 ;; so we force it to always insert a tab here.
88 (eq indent-line-function 'indent-to-left-margin)
89 (and (not tab-always-indent)
90 (or (> (current-column) (current-indentation))
91 (eq this-command last-command))))
92 (insert-tab arg))
93 ;; Those functions are meant specifically for tabbing and not for
94 ;; indenting, so we can't pass them to indent-according-to-mode.
95 ((memq indent-line-function '(indent-relative indent-relative-maybe))
96 (funcall indent-line-function))
97 (t ;; The normal case.
98 (indent-according-to-mode))))
100 (defun insert-tab (&optional arg)
101 (let ((count (prefix-numeric-value arg)))
102 (if (and abbrev-mode
103 (eq (char-syntax (preceding-char)) ?w))
104 (expand-abbrev))
105 (if indent-tabs-mode
106 (insert-char ?\t count)
107 (indent-to (* tab-width (+ count (/ (current-column) tab-width)))))))
109 (defun indent-rigidly (start end arg)
110 "Indent all lines starting in the region sideways by ARG columns.
111 Called from a program, takes three arguments, START, END and ARG.
112 You can remove all indentation from a region by giving a large negative ARG."
113 (interactive "r\np")
114 (save-excursion
115 (goto-char end)
116 (setq end (point-marker))
117 (goto-char start)
118 (or (bolp) (forward-line 1))
119 (while (< (point) end)
120 (let ((indent (current-indentation))
121 eol-flag)
122 (save-excursion
123 (skip-chars-forward " \t")
124 (setq eol-flag (eolp)))
125 (or eol-flag
126 (indent-to (max 0 (+ indent arg)) 0))
127 (delete-region (point) (progn (skip-chars-forward " \t") (point))))
128 (forward-line 1))
129 (move-marker end nil)))
131 (defun indent-line-to (column)
132 "Indent current line to COLUMN.
133 This function removes or adds spaces and tabs at beginning of line
134 only if necessary. It leaves point at end of indentation."
135 (back-to-indentation)
136 (let ((cur-col (current-column)))
137 (cond ((< cur-col column)
138 (if (>= (- column (* (/ cur-col tab-width) tab-width)) tab-width)
139 (delete-region (point)
140 (progn (skip-chars-backward " ") (point))))
141 (indent-to column))
142 ((> cur-col column) ; too far right (after tab?)
143 (delete-region (progn (move-to-column column t) (point))
144 (progn (back-to-indentation) (point)))))))
146 (defun current-left-margin ()
147 "Return the left margin to use for this line.
148 This is the value of the buffer-local variable `left-margin' plus the value
149 of the `left-margin' text-property at the start of the line."
150 (save-excursion
151 (back-to-indentation)
152 (max 0
153 (+ left-margin (or (get-text-property
154 (if (and (eobp) (not (bobp)))
155 (1- (point)) (point))
156 'left-margin) 0)))))
158 (defun move-to-left-margin (&optional n force)
159 "Move to the left margin of the current line.
160 With optional argument, move forward N-1 lines first.
161 The column moved to is the one given by the `current-left-margin' function.
162 If the line's indentation appears to be wrong, and this command is called
163 interactively or with optional argument FORCE, it will be fixed."
164 (interactive (list (prefix-numeric-value current-prefix-arg) t))
165 (beginning-of-line n)
166 (skip-chars-forward " \t")
167 (let ((lm (current-left-margin))
168 (cc (current-column)))
169 (cond ((> cc lm)
170 (if (> (move-to-column lm force) lm)
171 ;; If lm is in a tab and we are not forcing, move before tab
172 (backward-char 1)))
173 ((and force (< cc lm))
174 (indent-to-left-margin)))))
176 ;; This used to be the default indent-line-function,
177 ;; used in Fundamental Mode, Text Mode, etc.
178 (defun indent-to-left-margin ()
179 "Indent current line to the column given by `current-left-margin'."
180 (indent-line-to (current-left-margin)))
182 (defun delete-to-left-margin (&optional from to)
183 "Remove left margin indentation from a region.
184 This deletes to the column given by `current-left-margin'.
185 In no case will it delete non-whitespace.
186 Args FROM and TO are optional; default is the whole buffer."
187 (save-excursion
188 (goto-char (or to (point-max)))
189 (setq to (point-marker))
190 (goto-char (or from (point-min)))
191 (or (bolp) (forward-line 1))
192 (while (< (point) to)
193 (delete-region (point) (progn (move-to-left-margin nil t) (point)))
194 (forward-line 1))
195 (move-marker to nil)))
197 (defun set-left-margin (from to lm)
198 "Set the left margin of the region to WIDTH.
199 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
200 (interactive "r\nNSet left margin to column: ")
201 (if (interactive-p) (setq lm (prefix-numeric-value lm)))
202 (save-excursion
203 ;; If inside indentation, start from BOL.
204 (goto-char from)
205 (skip-chars-backward " \t")
206 (if (bolp) (setq from (point)))
207 ;; Place end after whitespace
208 (goto-char to)
209 (skip-chars-forward " \t")
210 (setq to (point-marker)))
211 ;; Delete margin indentation first, but keep paragraph indentation.
212 (delete-to-left-margin from to)
213 (put-text-property from to 'left-margin lm)
214 (indent-rigidly from to lm)
215 (if auto-fill-function (save-excursion (fill-region from to nil t t)))
216 (move-marker to nil))
218 (defun set-right-margin (from to lm)
219 "Set the right margin of the region to WIDTH.
220 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
221 (interactive "r\nNSet right margin to width: ")
222 (if (interactive-p) (setq lm (prefix-numeric-value lm)))
223 (save-excursion
224 (goto-char from)
225 (skip-chars-backward " \t")
226 (if (bolp) (setq from (point))))
227 (put-text-property from to 'right-margin lm)
228 (if auto-fill-function (save-excursion (fill-region from to nil t t))))
230 (defun alter-text-property (from to prop func &optional object)
231 "Programmatically change value of a text-property.
232 For each region between FROM and TO that has a single value for PROPERTY,
233 apply FUNCTION to that value and sets the property to the function's result.
234 Optional fifth argument OBJECT specifies the string or buffer to operate on."
235 (let ((begin from)
236 end val)
237 (while (setq val (get-text-property begin prop object)
238 end (text-property-not-all begin to prop val object))
239 (put-text-property begin end prop (funcall func val) object)
240 (setq begin end))
241 (if (< begin to)
242 (put-text-property begin to prop (funcall func val) object))))
244 (defun increase-left-margin (from to inc)
245 "Increase or decrease the left-margin of the region.
246 With no prefix argument, this adds `standard-indent' of indentation.
247 A prefix arg (optional third arg INC noninteractively) specifies the amount
248 to change the margin by, in characters.
249 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
250 (interactive "*r\nP")
251 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
252 (save-excursion
253 (goto-char from)
254 (skip-chars-backward " \t")
255 (if (bolp) (setq from (point)))
256 (goto-char to)
257 (setq to (point-marker)))
258 (alter-text-property from to 'left-margin
259 (lambda (v) (max (- left-margin) (+ inc (or v 0)))))
260 (indent-rigidly from to inc)
261 (if auto-fill-function (save-excursion (fill-region from to nil t t)))
262 (move-marker to nil))
264 (defun decrease-left-margin (from to inc)
265 "Make the left margin of the region smaller.
266 With no prefix argument, decrease the indentation by `standard-indent'.
267 A prefix arg (optional third arg INC noninteractively) specifies the amount
268 to change the margin by, in characters.
269 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
270 (interactive "*r\nP")
271 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
272 (increase-left-margin from to (- inc)))
274 (defun increase-right-margin (from to inc)
275 "Increase the right-margin of the region.
276 With no prefix argument, increase the right margin by `standard-indent'.
277 A prefix arg (optional third arg INC noninteractively) specifies the amount
278 to change the margin by, in characters. A negative argument decreases
279 the right margin width.
280 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
281 (interactive "r\nP")
282 (if (interactive-p)
283 (setq inc (if inc (prefix-numeric-value current-prefix-arg)
284 standard-indent)))
285 (save-excursion
286 (alter-text-property from to 'right-margin
287 (lambda (v) (+ inc (or v 0))))
288 (if auto-fill-function
289 (fill-region from to nil t t))))
291 (defun decrease-right-margin (from to inc)
292 "Make the right margin of the region smaller.
293 With no prefix argument, decrease the right margin by `standard-indent'.
294 A prefix arg (optional third arg INC noninteractively) specifies the amount
295 of width to remove, in characters. A negative argument increases
296 the right margin width.
297 If `auto-fill-mode' is active, re-fills region to fit in new margin."
298 (interactive "*r\nP")
299 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
300 (increase-right-margin from to (- inc)))
302 (defun beginning-of-line-text (&optional n)
303 "Move to the beginning of the text on this line.
304 With optional argument, move forward N-1 lines first.
305 From the beginning of the line, moves past the left-margin indentation, the
306 fill-prefix, and any indentation used for centering or right-justifying the
307 line, but does not move past any whitespace that was explicitly inserted
308 \(such as a tab used to indent the first line of a paragraph)."
309 (interactive "p")
310 (beginning-of-line n)
311 (skip-chars-forward " \t")
312 ;; Skip over fill-prefix.
313 (if (and fill-prefix
314 (not (string-equal fill-prefix "")))
315 (if (equal fill-prefix
316 (buffer-substring
317 (point) (min (point-max) (+ (length fill-prefix) (point)))))
318 (forward-char (length fill-prefix)))
319 (if (and adaptive-fill-mode adaptive-fill-regexp
320 (looking-at adaptive-fill-regexp))
321 (goto-char (match-end 0))))
322 ;; Skip centering or flushright indentation
323 (if (memq (current-justification) '(center right))
324 (skip-chars-forward " \t")))
326 (defvar indent-region-function nil
327 "Short cut function to indent region using `indent-according-to-mode'.
328 A value of nil means really run `indent-according-to-mode' on each line.")
330 (defun indent-region (start end &optional column)
331 "Indent each nonblank line in the region.
332 A numeric prefix argument specifies a column: indent each line to that column.
334 With no prefix argument, the command chooses one of these methods and
335 indents all the lines with it:
337 1) If `fill-prefix' is non-nil, insert `fill-prefix' at the
338 beginning of each line in the region that does not already begin
339 with it.
340 2) If `indent-region-function' is non-nil, call that function
341 to indent the region.
342 3) Indent each line as specified by the variable `indent-line-function'.
344 Called from a program, START and END specify the region to indent.
345 If the third argument COLUMN is an integer, it specifies the
346 column to indent to; if it is nil, use one of the three methods above."
347 (interactive "r\nP")
348 (if (null column)
349 (if fill-prefix
350 (save-excursion
351 (goto-char end)
352 (setq end (point-marker))
353 (goto-char start)
354 (let ((regexp (regexp-quote fill-prefix)))
355 (while (< (point) end)
356 (or (looking-at regexp)
357 (and (bolp) (eolp))
358 (insert fill-prefix))
359 (forward-line 1))))
360 (if indent-region-function
361 (funcall indent-region-function start end)
362 (save-excursion
363 (setq end (copy-marker end))
364 (goto-char start)
365 (while (< (point) end)
366 (or (and (bolp) (eolp))
367 (funcall indent-line-function))
368 (forward-line 1))
369 (move-marker end nil))))
370 (setq column (prefix-numeric-value column))
371 (save-excursion
372 (goto-char end)
373 (setq end (point-marker))
374 (goto-char start)
375 (or (bolp) (forward-line 1))
376 (while (< (point) end)
377 (delete-region (point) (progn (skip-chars-forward " \t") (point)))
378 (or (eolp)
379 (indent-to column 0))
380 (forward-line 1))
381 (move-marker end nil))))
383 (defun indent-relative-maybe ()
384 "Indent a new line like previous nonblank line.
385 If the previous nonblank line has no indent points beyond the
386 column point starts at, this command does nothing.
388 See also `indent-relative'."
389 (interactive)
390 (indent-relative t))
392 (defun indent-relative (&optional unindented-ok)
393 "Space out to under next indent point in previous nonblank line.
394 An indent point is a non-whitespace character following whitespace.
395 The following line shows the indentation points in this line.
396 ^ ^ ^ ^ ^ ^ ^ ^ ^
397 If the previous nonblank line has no indent points beyond the
398 column point starts at, `tab-to-tab-stop' is done instead, unless
399 this command is invoked with a numeric argument, in which case it
400 does nothing.
402 See also `indent-relative-maybe'."
403 (interactive "P")
404 (if (and abbrev-mode
405 (eq (char-syntax (preceding-char)) ?w))
406 (expand-abbrev))
407 (let ((start-column (current-column))
408 indent)
409 (save-excursion
410 (beginning-of-line)
411 (if (re-search-backward "^[^\n]" nil t)
412 (let ((end (save-excursion (forward-line 1) (point))))
413 (move-to-column start-column)
414 ;; Is start-column inside a tab on this line?
415 (if (> (current-column) start-column)
416 (backward-char 1))
417 (or (looking-at "[ \t]")
418 unindented-ok
419 (skip-chars-forward "^ \t" end))
420 (skip-chars-forward " \t" end)
421 (or (= (point) end) (setq indent (current-column))))))
422 (if indent
423 (let ((opoint (point-marker)))
424 (indent-to indent 0)
425 (if (> opoint (point))
426 (goto-char opoint))
427 (move-marker opoint nil))
428 (tab-to-tab-stop))))
430 (defcustom tab-stop-list
431 '(8 16 24 32 40 48 56 64 72 80 88 96 104 112 120)
432 "*List of tab stop positions used by `tab-to-tab-stop'.
433 This should be a list of integers, ordered from smallest to largest."
434 :group 'indent
435 :type '(repeat integer))
437 (defvar edit-tab-stops-map
438 (let ((map (make-sparse-keymap)))
439 (define-key map "\C-x\C-s" 'edit-tab-stops-note-changes)
440 (define-key map "\C-c\C-c" 'edit-tab-stops-note-changes)
441 map)
442 "Keymap used in `edit-tab-stops'.")
444 (defvar edit-tab-stops-buffer nil
445 "Buffer whose tab stops are being edited--in case
446 the variable `tab-stop-list' is local in that buffer.")
448 (defun edit-tab-stops ()
449 "Edit the tab stops used by `tab-to-tab-stop'.
450 Creates a buffer *Tab Stops* containing text describing the tab stops.
451 A colon indicates a column where there is a tab stop.
452 You can add or remove colons and then do \\<edit-tab-stops-map>\\[edit-tab-stops-note-changes] to make changes take effect."
453 (interactive)
454 (setq edit-tab-stops-buffer (current-buffer))
455 (switch-to-buffer (get-buffer-create "*Tab Stops*"))
456 (use-local-map edit-tab-stops-map)
457 (make-local-variable 'indent-tabs-mode)
458 (setq indent-tabs-mode nil)
459 (overwrite-mode 1)
460 (setq truncate-lines t)
461 (erase-buffer)
462 (let ((tabs tab-stop-list))
463 (while tabs
464 (indent-to (car tabs) 0)
465 (insert ?:)
466 (setq tabs (cdr tabs))))
467 (let ((count 0))
468 (insert ?\n)
469 (while (< count 8)
470 (insert (+ count ?0))
471 (insert " ")
472 (setq count (1+ count)))
473 (insert ?\n)
474 (while (> count 0)
475 (insert "0123456789")
476 (setq count (1- count))))
477 (insert "\nTo install changes, type C-c C-c")
478 (goto-char (point-min)))
480 (defun edit-tab-stops-note-changes ()
481 "Put edited tab stops into effect."
482 (interactive)
483 (let (tabs)
484 (save-excursion
485 (goto-char 1)
486 (end-of-line)
487 (while (search-backward ":" nil t)
488 (setq tabs (cons (current-column) tabs))))
489 (bury-buffer (prog1 (current-buffer)
490 (switch-to-buffer edit-tab-stops-buffer)))
491 (setq tab-stop-list tabs))
492 (message "Tab stops installed"))
494 (defun tab-to-tab-stop ()
495 "Insert spaces or tabs to next defined tab-stop column.
496 The variable `tab-stop-list' is a list of columns at which there are tab stops.
497 Use \\[edit-tab-stops] to edit them interactively."
498 (interactive)
499 (and abbrev-mode (= (char-syntax (preceding-char)) ?w)
500 (expand-abbrev))
501 (let ((tabs tab-stop-list))
502 (while (and tabs (>= (current-column) (car tabs)))
503 (setq tabs (cdr tabs)))
504 (if tabs
505 (let ((opoint (point)))
506 (delete-horizontal-space t)
507 (indent-to (car tabs)))
508 (insert ?\ ))))
510 (defun move-to-tab-stop ()
511 "Move point to next defined tab-stop column.
512 The variable `tab-stop-list' is a list of columns at which there are tab stops.
513 Use \\[edit-tab-stops] to edit them interactively."
514 (interactive)
515 (let ((tabs tab-stop-list))
516 (while (and tabs (>= (current-column) (car tabs)))
517 (setq tabs (cdr tabs)))
518 (if tabs
519 (let ((before (point)))
520 (move-to-column (car tabs) t)
521 (save-excursion
522 (goto-char before)
523 ;; If we just added a tab, or moved over one,
524 ;; delete any superfluous spaces before the old point.
525 (if (and (eq (preceding-char) ?\ )
526 (eq (following-char) ?\t))
527 (let ((tabend (* (/ (current-column) tab-width) tab-width)))
528 (while (and (> (current-column) tabend)
529 (eq (preceding-char) ?\ ))
530 (forward-char -1))
531 (delete-region (point) before))))))))
533 (define-key global-map "\t" 'indent-for-tab-command)
534 (define-key esc-map "\C-\\" 'indent-region)
535 (define-key ctl-x-map "\t" 'indent-rigidly)
536 (define-key esc-map "i" 'tab-to-tab-stop)
538 ;;; indent.el ends here