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1 ;;; indent.el --- indentation commands for Emacs
3 ;; Copyright (C) 1985, 1995, 2001-2011 Free Software Foundation, Inc.
5 ;; Maintainer: FSF
6 ;; Package: emacs
8 ;; This file is part of GNU Emacs.
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 3 of the License, or
13 ;; (at your option) any later version.
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.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
23 ;;; Commentary:
25 ;; Commands for making and changing indentation in text. These are
26 ;; described in the Emacs manual.
28 ;;; Code:
30 (defgroup indent nil
31 "Indentation commands."
32 :group 'editing)
34 (defcustom standard-indent 4
35 "Default number of columns for margin-changing functions to indent."
36 :group 'indent
37 :type 'integer)
39 (defvar indent-line-function 'indent-relative
40 "Function to indent the current line.
41 This function will be called with no arguments.
42 If it is called somewhere where auto-indentation cannot be done
43 \(e.g. inside a string), the function should simply return `noindent'.
44 Setting this function is all you need to make TAB indent appropriately.
45 Don't rebind TAB unless you really need to.")
47 (defcustom tab-always-indent t
48 "Controls the operation of the TAB key.
49 If t, hitting TAB always just indents the current line.
50 If nil, hitting TAB indents the current line if point is at the left margin
51 or in the line's indentation, otherwise it inserts a \"real\" TAB character.
52 If `complete', TAB first tries to indent the current line, and if the line
53 was already indented, then try to complete the thing at point.
55 Some programming language modes have their own variable to control this,
56 e.g., `c-tab-always-indent', and do not respect this variable."
57 :group 'indent
58 :type '(choice
59 (const :tag "Always indent" t)
60 (const :tag "Indent if inside indentation, else TAB" nil)
61 (const :tag "Indent, or if already indented complete" complete)))
64 (defun indent-according-to-mode ()
65 "Indent line in proper way for current major mode.
66 The buffer-local variable `indent-line-function' determines how to do this,
67 but the functions `indent-relative' and `indent-relative-maybe' are
68 special; we don't actually use them here."
69 (interactive)
70 (syntax-propertize (line-end-position))
71 (if (memq indent-line-function
72 '(indent-relative indent-relative-maybe))
73 ;; These functions are used for tabbing, but can't be used for
74 ;; indenting. Replace with something ad-hoc.
75 (let ((column (save-excursion
76 (beginning-of-line)
77 (skip-chars-backward "\n \t")
78 (beginning-of-line)
79 (current-indentation))))
80 (if (<= (current-column) (current-indentation))
81 (indent-line-to column)
82 (save-excursion (indent-line-to column))))
83 ;; The normal case.
84 (funcall indent-line-function)))
86 (defun indent-for-tab-command (&optional arg)
87 "Indent line or region in proper way for current major mode or insert a tab.
88 Depending on `tab-always-indent', either insert a tab or indent.
90 In most major modes, if point was in the current line's indentation,
91 it is moved to the first non-whitespace character after indenting;
92 otherwise it stays at the same position in the text.
94 If a prefix argument is given, also rigidly indent the entire
95 balanced expression which starts at the beginning of the current
96 line to reflect the current line's change in indentation.
98 If `transient-mark-mode' is turned on and the region is active,
99 indent the region (in this case, any prefix argument is ignored).
101 The function actually called to indent the line is determined by the value of
102 `indent-line-function'."
103 (interactive "P")
104 (cond
105 ;; The region is active, indent it.
106 ((use-region-p)
107 (indent-region (region-beginning) (region-end)))
108 ((or ;; indent-to-left-margin is only meant for indenting,
109 ;; so we force it to always insert a tab here.
110 (eq indent-line-function 'indent-to-left-margin)
111 (and (not tab-always-indent)
112 (or (> (current-column) (current-indentation))
113 (eq this-command last-command))))
114 (insert-tab arg))
116 (let ((old-tick (buffer-chars-modified-tick))
117 (old-point (point))
118 (old-indent (current-indentation)))
120 ;; Indent the line.
121 (funcall indent-line-function)
123 (cond
124 ;; If the text was already indented right, try completion.
125 ((and (eq tab-always-indent 'complete)
126 (eq old-point (point))
127 (eq old-tick (buffer-chars-modified-tick)))
128 (completion-at-point))
130 ;; If a prefix argument was given, rigidly indent the following
131 ;; sexp to match the change in the current line's indentation.
132 (arg
133 (let ((end-marker
134 (save-excursion
135 (forward-line 0) (forward-sexp) (point-marker)))
136 (indentation-change (- (current-indentation) old-indent)))
137 (save-excursion
138 (forward-line 1)
139 (when (and (not (zerop indentation-change))
140 (< (point) end-marker))
141 (indent-rigidly (point) end-marker indentation-change))))))))))
143 (defun insert-tab (&optional arg)
144 (let ((count (prefix-numeric-value arg)))
145 (if (and abbrev-mode
146 (eq (char-syntax (preceding-char)) ?w))
147 (expand-abbrev))
148 (if indent-tabs-mode
149 (insert-char ?\t count)
150 (indent-to (* tab-width (+ count (/ (current-column) tab-width)))))))
152 (defun indent-rigidly (start end arg)
153 "Indent all lines starting in the region sideways by ARG columns.
154 Called from a program, takes three arguments, START, END and ARG.
155 You can remove all indentation from a region by giving a large negative ARG."
156 (interactive "r\np")
157 (save-excursion
158 (goto-char end)
159 (setq end (point-marker))
160 (goto-char start)
161 (or (bolp) (forward-line 1))
162 (while (< (point) end)
163 (let ((indent (current-indentation))
164 eol-flag)
165 (save-excursion
166 (skip-chars-forward " \t")
167 (setq eol-flag (eolp)))
168 (or eol-flag
169 (indent-to (max 0 (+ indent arg)) 0))
170 (delete-region (point) (progn (skip-chars-forward " \t") (point))))
171 (forward-line 1))
172 (move-marker end nil)))
174 (defun indent-line-to (column)
175 "Indent current line to COLUMN.
176 This function removes or adds spaces and tabs at beginning of line
177 only if necessary. It leaves point at end of indentation."
178 (back-to-indentation)
179 (let ((cur-col (current-column)))
180 (cond ((< cur-col column)
181 (if (>= (- column (* (/ cur-col tab-width) tab-width)) tab-width)
182 (delete-region (point)
183 (progn (skip-chars-backward " ") (point))))
184 (indent-to column))
185 ((> cur-col column) ; too far right (after tab?)
186 (delete-region (progn (move-to-column column t) (point))
187 (progn (back-to-indentation) (point)))))))
189 (defun current-left-margin ()
190 "Return the left margin to use for this line.
191 This is the value of the buffer-local variable `left-margin' plus the value
192 of the `left-margin' text-property at the start of the line."
193 (save-excursion
194 (back-to-indentation)
195 (max 0
196 (+ left-margin (or (get-text-property
197 (if (and (eobp) (not (bobp)))
198 (1- (point)) (point))
199 'left-margin) 0)))))
201 (defun move-to-left-margin (&optional n force)
202 "Move to the left margin of the current line.
203 With optional argument, move forward N-1 lines first.
204 The column moved to is the one given by the `current-left-margin' function.
205 If the line's indentation appears to be wrong, and this command is called
206 interactively or with optional argument FORCE, it will be fixed."
207 (interactive (list (prefix-numeric-value current-prefix-arg) t))
208 (beginning-of-line n)
209 (skip-chars-forward " \t")
210 (if (minibufferp (current-buffer))
211 (if (save-excursion (beginning-of-line) (bobp))
212 (goto-char (minibuffer-prompt-end))
213 (beginning-of-line))
214 (let ((lm (current-left-margin))
215 (cc (current-column)))
216 (cond ((> cc lm)
217 (if (> (move-to-column lm force) lm)
218 ;; If lm is in a tab and we are not forcing, move before tab
219 (backward-char 1)))
220 ((and force (< cc lm))
221 (indent-to-left-margin))))))
223 ;; This used to be the default indent-line-function,
224 ;; used in Fundamental Mode, Text Mode, etc.
225 (defun indent-to-left-margin ()
226 "Indent current line to the column given by `current-left-margin'."
227 (save-excursion (indent-line-to (current-left-margin)))
228 ;; If we are within the indentation, move past it.
229 (when (save-excursion
230 (skip-chars-backward " \t")
231 (bolp))
232 (skip-chars-forward " \t")))
234 (defun delete-to-left-margin (&optional from to)
235 "Remove left margin indentation from a region.
236 This deletes to the column given by `current-left-margin'.
237 In no case will it delete non-whitespace.
238 Args FROM and TO are optional; default is the whole buffer."
239 (save-excursion
240 (goto-char (or to (point-max)))
241 (setq to (point-marker))
242 (goto-char (or from (point-min)))
243 (or (bolp) (forward-line 1))
244 (while (< (point) to)
245 (delete-region (point) (progn (move-to-left-margin nil t) (point)))
246 (forward-line 1))
247 (move-marker to nil)))
249 (defun set-left-margin (from to width)
250 "Set the left margin of the region to WIDTH.
251 If `auto-fill-mode' is active, re-fill the region to fit the new margin.
253 Interactively, WIDTH is the prefix argument, if specified.
254 Without prefix argument, the command prompts for WIDTH."
255 (interactive "r\nNSet left margin to column: ")
256 (save-excursion
257 ;; If inside indentation, start from BOL.
258 (goto-char from)
259 (skip-chars-backward " \t")
260 (if (bolp) (setq from (point)))
261 ;; Place end after whitespace
262 (goto-char to)
263 (skip-chars-forward " \t")
264 (setq to (point-marker)))
265 ;; Delete margin indentation first, but keep paragraph indentation.
266 (delete-to-left-margin from to)
267 (put-text-property from to 'left-margin width)
268 (indent-rigidly from to width)
269 (if auto-fill-function (save-excursion (fill-region from to nil t t)))
270 (move-marker to nil))
272 (defun set-right-margin (from to width)
273 "Set the right margin of the region to WIDTH.
274 If `auto-fill-mode' is active, re-fill the region to fit the new margin.
276 Interactively, WIDTH is the prefix argument, if specified.
277 Without prefix argument, the command prompts for WIDTH."
278 (interactive "r\nNSet right margin to width: ")
279 (save-excursion
280 (goto-char from)
281 (skip-chars-backward " \t")
282 (if (bolp) (setq from (point))))
283 (put-text-property from to 'right-margin width)
284 (if auto-fill-function (save-excursion (fill-region from to nil t t))))
286 (defun alter-text-property (from to prop func &optional object)
287 "Programmatically change value of a text-property.
288 For each region between FROM and TO that has a single value for PROPERTY,
289 apply FUNCTION to that value and sets the property to the function's result.
290 Optional fifth argument OBJECT specifies the string or buffer to operate on."
291 (let ((begin from)
292 end val)
293 (while (setq val (get-text-property begin prop object)
294 end (text-property-not-all begin to prop val object))
295 (put-text-property begin end prop (funcall func val) object)
296 (setq begin end))
297 (if (< begin to)
298 (put-text-property begin to prop (funcall func val) object))))
300 (defun increase-left-margin (from to inc)
301 "Increase or decrease the left-margin of the region.
302 With no prefix argument, this adds `standard-indent' of indentation.
303 A prefix arg (optional third arg INC noninteractively) specifies the amount
304 to change the margin by, in characters.
305 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
306 (interactive "*r\nP")
307 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
308 (save-excursion
309 (goto-char from)
310 (skip-chars-backward " \t")
311 (if (bolp) (setq from (point)))
312 (goto-char to)
313 (setq to (point-marker)))
314 (alter-text-property from to 'left-margin
315 (lambda (v) (max (- left-margin) (+ inc (or v 0)))))
316 (indent-rigidly from to inc)
317 (if auto-fill-function (save-excursion (fill-region from to nil t t)))
318 (move-marker to nil))
320 (defun decrease-left-margin (from to inc)
321 "Make the left margin of the region smaller.
322 With no prefix argument, decrease the indentation by `standard-indent'.
323 A prefix arg (optional third arg INC noninteractively) specifies the amount
324 to change the margin by, in characters.
325 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
326 (interactive "*r\nP")
327 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
328 (increase-left-margin from to (- inc)))
330 (defun increase-right-margin (from to inc)
331 "Increase the right-margin of the region.
332 With no prefix argument, increase the right margin by `standard-indent'.
333 A prefix arg (optional third arg INC noninteractively) specifies the amount
334 to change the margin by, in characters. A negative argument decreases
335 the right margin width.
336 If `auto-fill-mode' is active, re-fill the region to fit the new margin."
337 (interactive "r\nP")
338 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
339 (save-excursion
340 (alter-text-property from to 'right-margin
341 (lambda (v) (+ inc (or v 0))))
342 (if auto-fill-function
343 (fill-region from to nil t t))))
345 (defun decrease-right-margin (from to inc)
346 "Make the right margin of the region smaller.
347 With no prefix argument, decrease the right margin by `standard-indent'.
348 A prefix arg (optional third arg INC noninteractively) specifies the amount
349 of width to remove, in characters. A negative argument increases
350 the right margin width.
351 If `auto-fill-mode' is active, re-fills region to fit in new margin."
352 (interactive "*r\nP")
353 (setq inc (if inc (prefix-numeric-value inc) standard-indent))
354 (increase-right-margin from to (- inc)))
356 (defun beginning-of-line-text (&optional n)
357 "Move to the beginning of the text on this line.
358 With optional argument, move forward N-1 lines first.
359 From the beginning of the line, moves past the left-margin indentation, the
360 fill-prefix, and any indentation used for centering or right-justifying the
361 line, but does not move past any whitespace that was explicitly inserted
362 \(such as a tab used to indent the first line of a paragraph)."
363 (interactive "p")
364 (beginning-of-line n)
365 (skip-chars-forward " \t")
366 ;; Skip over fill-prefix.
367 (if (and fill-prefix
368 (not (string-equal fill-prefix "")))
369 (if (equal fill-prefix
370 (buffer-substring
371 (point) (min (point-max) (+ (length fill-prefix) (point)))))
372 (forward-char (length fill-prefix)))
373 (if (and adaptive-fill-mode adaptive-fill-regexp
374 (looking-at adaptive-fill-regexp))
375 (goto-char (match-end 0))))
376 ;; Skip centering or flushright indentation
377 (if (memq (current-justification) '(center right))
378 (skip-chars-forward " \t")))
380 (defvar indent-region-function nil
381 "Short cut function to indent region using `indent-according-to-mode'.
382 A value of nil means really run `indent-according-to-mode' on each line.")
384 (defun indent-region (start end &optional column)
385 "Indent each nonblank line in the region.
386 A numeric prefix argument specifies a column: indent each line to that column.
388 With no prefix argument, the command chooses one of these methods and
389 indents all the lines with it:
391 1) If `fill-prefix' is non-nil, insert `fill-prefix' at the
392 beginning of each line in the region that does not already begin
393 with it.
394 2) If `indent-region-function' is non-nil, call that function
395 to indent the region.
396 3) Indent each line as specified by the variable `indent-line-function'.
398 Called from a program, START and END specify the region to indent.
399 If the third argument COLUMN is an integer, it specifies the
400 column to indent to; if it is nil, use one of the three methods above."
401 (interactive "r\nP")
402 (if (null column)
403 (if fill-prefix
404 (save-excursion
405 (goto-char end)
406 (setq end (point-marker))
407 (goto-char start)
408 (let ((regexp (regexp-quote fill-prefix)))
409 (while (< (point) end)
410 (or (looking-at regexp)
411 (and (bolp) (eolp))
412 (insert fill-prefix))
413 (forward-line 1))))
414 (if indent-region-function
415 (funcall indent-region-function start end)
416 (save-excursion
417 (setq end (copy-marker end))
418 (goto-char start)
419 (while (< (point) end)
420 (or (and (bolp) (eolp))
421 (indent-according-to-mode))
422 (forward-line 1))
423 (move-marker end nil))))
424 (setq column (prefix-numeric-value column))
425 (save-excursion
426 (goto-char end)
427 (setq end (point-marker))
428 (goto-char start)
429 (or (bolp) (forward-line 1))
430 (while (< (point) end)
431 (delete-region (point) (progn (skip-chars-forward " \t") (point)))
432 (or (eolp)
433 (indent-to column 0))
434 (forward-line 1))
435 (move-marker end nil)))
436 ;; In most cases, reindenting modifies the buffer, but it may also
437 ;; leave it unmodified, in which case we have to deactivate the mark
438 ;; by hand.
439 (deactivate-mark))
441 (defun indent-relative-maybe ()
442 "Indent a new line like previous nonblank line.
443 If the previous nonblank line has no indent points beyond the
444 column point starts at, this command does nothing.
446 See also `indent-relative'."
447 (interactive)
448 (indent-relative t))
450 (defun indent-relative (&optional unindented-ok)
451 "Space out to under next indent point in previous nonblank line.
452 An indent point is a non-whitespace character following whitespace.
453 The following line shows the indentation points in this line.
454 ^ ^ ^ ^ ^ ^ ^ ^ ^
455 If the previous nonblank line has no indent points beyond the
456 column point starts at, `tab-to-tab-stop' is done instead, unless
457 this command is invoked with a numeric argument, in which case it
458 does nothing.
460 See also `indent-relative-maybe'."
461 (interactive "P")
462 (if (and abbrev-mode
463 (eq (char-syntax (preceding-char)) ?w))
464 (expand-abbrev))
465 (let ((start-column (current-column))
466 indent)
467 (save-excursion
468 (beginning-of-line)
469 (if (re-search-backward "^[^\n]" nil t)
470 (let ((end (save-excursion (forward-line 1) (point))))
471 (move-to-column start-column)
472 ;; Is start-column inside a tab on this line?
473 (if (> (current-column) start-column)
474 (backward-char 1))
475 (or (looking-at "[ \t]")
476 unindented-ok
477 (skip-chars-forward "^ \t" end))
478 (skip-chars-forward " \t" end)
479 (or (= (point) end) (setq indent (current-column))))))
480 (if indent
481 (let ((opoint (point-marker)))
482 (indent-to indent 0)
483 (if (> opoint (point))
484 (goto-char opoint))
485 (move-marker opoint nil))
486 (tab-to-tab-stop))))
488 (defcustom tab-stop-list
489 '(8 16 24 32 40 48 56 64 72 80 88 96 104 112 120)
490 "List of tab stop positions used by `tab-to-tab-stop'.
491 This should be a list of integers, ordered from smallest to largest."
492 :group 'indent
493 :type '(repeat integer))
494 (put 'tab-stop-list 'safe-local-variable 'listp)
496 (defvar edit-tab-stops-map
497 (let ((map (make-sparse-keymap)))
498 (define-key map "\C-x\C-s" 'edit-tab-stops-note-changes)
499 (define-key map "\C-c\C-c" 'edit-tab-stops-note-changes)
500 map)
501 "Keymap used in `edit-tab-stops'.")
503 (defvar edit-tab-stops-buffer nil
504 "Buffer whose tab stops are being edited.
505 This matters if the variable `tab-stop-list' is local in that buffer.")
507 (defun edit-tab-stops ()
508 "Edit the tab stops used by `tab-to-tab-stop'.
509 Creates a buffer *Tab Stops* containing text describing the tab stops.
510 A colon indicates a column where there is a tab stop.
511 You can add or remove colons and then do \\<edit-tab-stops-map>\\[edit-tab-stops-note-changes] to make changes take effect."
512 (interactive)
513 (setq edit-tab-stops-buffer (current-buffer))
514 (switch-to-buffer (get-buffer-create "*Tab Stops*"))
515 (use-local-map edit-tab-stops-map)
516 (make-local-variable 'indent-tabs-mode)
517 (setq indent-tabs-mode nil)
518 (overwrite-mode 1)
519 (setq truncate-lines t)
520 (erase-buffer)
521 (let ((tabs tab-stop-list))
522 (while tabs
523 (indent-to (car tabs) 0)
524 (insert ?:)
525 (setq tabs (cdr tabs))))
526 (let ((count 0))
527 (insert ?\n)
528 (while (< count 8)
529 (insert (+ count ?0))
530 (insert " ")
531 (setq count (1+ count)))
532 (insert ?\n)
533 (while (> count 0)
534 (insert "0123456789")
535 (setq count (1- count))))
536 (insert "\nTo install changes, type C-c C-c")
537 (goto-char (point-min)))
539 (defun edit-tab-stops-note-changes ()
540 "Put edited tab stops into effect."
541 (interactive)
542 (let (tabs)
543 (save-excursion
544 (goto-char 1)
545 (end-of-line)
546 (while (search-backward ":" nil t)
547 (setq tabs (cons (current-column) tabs))))
548 (bury-buffer (prog1 (current-buffer)
549 (switch-to-buffer edit-tab-stops-buffer)))
550 (setq tab-stop-list tabs))
551 (message "Tab stops installed"))
553 (defun tab-to-tab-stop ()
554 "Insert spaces or tabs to next defined tab-stop column.
555 The variable `tab-stop-list' is a list of columns at which there are tab stops.
556 Use \\[edit-tab-stops] to edit them interactively."
557 (interactive)
558 (and abbrev-mode (= (char-syntax (preceding-char)) ?w)
559 (expand-abbrev))
560 (let ((tabs tab-stop-list))
561 (while (and tabs (>= (current-column) (car tabs)))
562 (setq tabs (cdr tabs)))
563 (if tabs
564 (progn
565 (delete-horizontal-space t)
566 (indent-to (car tabs)))
567 (insert ?\s))))
569 (defun move-to-tab-stop ()
570 "Move point to next defined tab-stop column.
571 The variable `tab-stop-list' is a list of columns at which there are tab stops.
572 Use \\[edit-tab-stops] to edit them interactively."
573 (interactive)
574 (let ((tabs tab-stop-list))
575 (while (and tabs (>= (current-column) (car tabs)))
576 (setq tabs (cdr tabs)))
577 (if tabs
578 (let ((before (point)))
579 (move-to-column (car tabs) t)
580 (save-excursion
581 (goto-char before)
582 ;; If we just added a tab, or moved over one,
583 ;; delete any superfluous spaces before the old point.
584 (if (and (eq (preceding-char) ?\s)
585 (eq (following-char) ?\t))
586 (let ((tabend (* (/ (current-column) tab-width) tab-width)))
587 (while (and (> (current-column) tabend)
588 (eq (preceding-char) ?\s))
589 (forward-char -1))
590 (delete-region (point) before))))))))
592 (define-key global-map "\t" 'indent-for-tab-command)
593 (define-key esc-map "\C-\\" 'indent-region)
594 (define-key ctl-x-map "\t" 'indent-rigidly)
595 (define-key esc-map "i" 'tab-to-tab-stop)
597 ;;; indent.el ends here