Tweak interface of buffer-face-mode functions
[emacs.git] / lisp / jit-lock.el
blob594fdba4628b2d11db12681ae6af017b13d065b5
1 ;;; jit-lock.el --- just-in-time fontification
3 ;; Copyright (C) 1998, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
6 ;; Author: Gerd Moellmann <gerd@gnu.org>
7 ;; Keywords: faces files
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software: you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation, either version 3 of the License, or
14 ;; (at your option) any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
24 ;;; Commentary:
26 ;; Just-in-time fontification, triggered by C redisplay code.
28 ;;; Code:
31 (eval-when-compile
32 (require 'cl)
34 (defmacro with-buffer-unmodified (&rest body)
35 "Eval BODY, preserving the current buffer's modified state."
36 (declare (debug t))
37 (let ((modified (make-symbol "modified")))
38 `(let ((,modified (buffer-modified-p)))
39 (unwind-protect
40 (progn ,@body)
41 (unless ,modified
42 (restore-buffer-modified-p nil))))))
44 (defmacro with-buffer-prepared-for-jit-lock (&rest body)
45 "Execute BODY in current buffer, overriding several variables.
46 Preserves the `buffer-modified-p' state of the current buffer."
47 (declare (debug t))
48 `(with-buffer-unmodified
49 (let ((buffer-undo-list t)
50 (inhibit-read-only t)
51 (inhibit-point-motion-hooks t)
52 (inhibit-modification-hooks t)
53 deactivate-mark
54 buffer-file-name
55 buffer-file-truename)
56 ,@body))))
60 ;;; Customization.
62 (defgroup jit-lock nil
63 "Font Lock support mode to fontify just-in-time."
64 :version "21.1"
65 :group 'font-lock)
67 (defcustom jit-lock-chunk-size 500
68 "*Jit-lock fontifies chunks of at most this many characters at a time.
70 This variable controls both display-time and stealth fontification."
71 :type 'integer
72 :group 'jit-lock)
75 (defcustom jit-lock-stealth-time nil
76 "*Time in seconds to wait before beginning stealth fontification.
77 Stealth fontification occurs if there is no input within this time.
78 If nil, stealth fontification is never performed.
80 The value of this variable is used when JIT Lock mode is turned on."
81 :type '(choice (const :tag "never" nil)
82 (number :tag "seconds" :value 16))
83 :group 'jit-lock)
86 (defcustom jit-lock-stealth-nice 0.5
87 "*Time in seconds to pause between chunks of stealth fontification.
88 Each iteration of stealth fontification is separated by this amount of time,
89 thus reducing the demand that stealth fontification makes on the system.
90 If nil, means stealth fontification is never paused.
91 To reduce machine load during stealth fontification, at the cost of stealth
92 taking longer to fontify, you could increase the value of this variable.
93 See also `jit-lock-stealth-load'."
94 :type '(choice (const :tag "never" nil)
95 (number :tag "seconds"))
96 :group 'jit-lock)
99 (defcustom jit-lock-stealth-load
100 (if (condition-case nil (load-average) (error)) 200)
101 "*Load in percentage above which stealth fontification is suspended.
102 Stealth fontification pauses when the system short-term load average (as
103 returned by the function `load-average' if supported) goes above this level,
104 thus reducing the demand that stealth fontification makes on the system.
105 If nil, means stealth fontification is never suspended.
106 To reduce machine load during stealth fontification, at the cost of stealth
107 taking longer to fontify, you could reduce the value of this variable.
108 See also `jit-lock-stealth-nice'."
109 :type (if (condition-case nil (load-average) (error))
110 '(choice (const :tag "never" nil)
111 (integer :tag "load"))
112 '(const :format "%t: unsupported\n" nil))
113 :group 'jit-lock)
116 (defcustom jit-lock-stealth-verbose nil
117 "*If non-nil, means stealth fontification should show status messages."
118 :type 'boolean
119 :group 'jit-lock)
122 (defvaralias 'jit-lock-defer-contextually 'jit-lock-contextually)
123 (defcustom jit-lock-contextually 'syntax-driven
124 "*If non-nil, means fontification should be syntactically true.
125 If nil, means fontification occurs only on those lines modified. This
126 means where modification on a line causes syntactic change on subsequent lines,
127 those subsequent lines are not refontified to reflect their new context.
128 If t, means fontification occurs on those lines modified and all
129 subsequent lines. This means those subsequent lines are refontified to reflect
130 their new syntactic context, after `jit-lock-context-time' seconds.
131 If any other value, e.g., `syntax-driven', means syntactically true
132 fontification occurs only if syntactic fontification is performed using the
133 buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil.
135 The value of this variable is used when JIT Lock mode is turned on."
136 :type '(choice (const :tag "never" nil)
137 (const :tag "always" t)
138 (other :tag "syntax-driven" syntax-driven))
139 :group 'jit-lock)
141 (defcustom jit-lock-context-time 0.5
142 "Idle time after which text is contextually refontified, if applicable."
143 :type '(number :tag "seconds")
144 :group 'jit-lock)
146 (defcustom jit-lock-defer-time nil ;; 0.25
147 "Idle time after which deferred fontification should take place.
148 If nil, fontification is not deferred."
149 :group 'jit-lock
150 :type '(choice (const :tag "never" nil)
151 (number :tag "seconds")))
153 ;;; Variables that are not customizable.
155 (defvar jit-lock-mode nil
156 "Non-nil means Just-in-time Lock mode is active.")
157 (make-variable-buffer-local 'jit-lock-mode)
159 (defvar jit-lock-functions nil
160 "Functions to do the actual fontification.
161 They are called with two arguments: the START and END of the region to fontify.")
162 (make-variable-buffer-local 'jit-lock-functions)
164 (defvar jit-lock-context-unfontify-pos nil
165 "Consider text after this position as contextually unfontified.
166 If nil, contextual fontification is disabled.")
167 (make-variable-buffer-local 'jit-lock-context-unfontify-pos)
170 (defvar jit-lock-stealth-timer nil
171 "Timer for stealth fontification in Just-in-time Lock mode.")
172 (defvar jit-lock-stealth-repeat-timer nil
173 "Timer for repeated stealth fontification in Just-in-time Lock mode.")
174 (defvar jit-lock-context-timer nil
175 "Timer for context fontification in Just-in-time Lock mode.")
176 (defvar jit-lock-defer-timer nil
177 "Timer for deferred fontification in Just-in-time Lock mode.")
179 (defvar jit-lock-defer-buffers nil
180 "List of buffers with pending deferred fontification.")
181 (defvar jit-lock-stealth-buffers nil
182 "List of buffers that are being fontified stealthily.")
184 ;;; JIT lock mode
186 (defun jit-lock-mode (arg)
187 "Toggle Just-in-time Lock mode.
188 Turn Just-in-time Lock mode on if and only if ARG is non-nil.
189 Enable it automatically by customizing group `font-lock'.
191 When Just-in-time Lock mode is enabled, fontification is different in the
192 following ways:
194 - Demand-driven buffer fontification triggered by Emacs C code.
195 This means initial fontification of the whole buffer does not occur.
196 Instead, fontification occurs when necessary, such as when scrolling
197 through the buffer would otherwise reveal unfontified areas. This is
198 useful if buffer fontification is too slow for large buffers.
200 - Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil.
201 This means remaining unfontified areas of buffers are fontified if Emacs has
202 been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle.
203 This is useful if any buffer has any deferred fontification.
205 - Deferred context fontification if `jit-lock-contextually' is
206 non-nil. This means fontification updates the buffer corresponding to
207 true syntactic context, after `jit-lock-context-time' seconds of Emacs
208 idle time, while Emacs remains idle. Otherwise, fontification occurs
209 on modified lines only, and subsequent lines can remain fontified
210 corresponding to previous syntactic contexts. This is useful where
211 strings or comments span lines.
213 Stealth fontification only occurs while the system remains unloaded.
214 If the system load rises above `jit-lock-stealth-load' percent, stealth
215 fontification is suspended. Stealth fontification intensity is controlled via
216 the variable `jit-lock-stealth-nice'."
217 (setq jit-lock-mode arg)
218 (cond (;; Turn Just-in-time Lock mode on.
219 jit-lock-mode
221 ;; Mark the buffer for refontification.
222 (jit-lock-refontify)
224 ;; Install an idle timer for stealth fontification.
225 (when (and jit-lock-stealth-time (null jit-lock-stealth-timer))
226 (setq jit-lock-stealth-timer
227 (run-with-idle-timer jit-lock-stealth-time t
228 'jit-lock-stealth-fontify)))
230 ;; Create, but do not activate, the idle timer for repeated
231 ;; stealth fontification.
232 (when (and jit-lock-stealth-time (null jit-lock-stealth-repeat-timer))
233 (setq jit-lock-stealth-repeat-timer (timer-create))
234 (timer-set-function jit-lock-stealth-repeat-timer
235 'jit-lock-stealth-fontify '(t)))
237 ;; Init deferred fontification timer.
238 (when (and jit-lock-defer-time (null jit-lock-defer-timer))
239 (setq jit-lock-defer-timer
240 (run-with-idle-timer jit-lock-defer-time t
241 'jit-lock-deferred-fontify)))
243 ;; Initialize contextual fontification if requested.
244 (when (eq jit-lock-contextually t)
245 (unless jit-lock-context-timer
246 (setq jit-lock-context-timer
247 (run-with-idle-timer jit-lock-context-time t
248 'jit-lock-context-fontify)))
249 (setq jit-lock-context-unfontify-pos
250 (or jit-lock-context-unfontify-pos (point-max))))
252 ;; Setup our hooks.
253 (add-hook 'after-change-functions 'jit-lock-after-change nil t)
254 (add-hook 'fontification-functions 'jit-lock-function))
256 ;; Turn Just-in-time Lock mode off.
258 ;; Cancel our idle timers.
259 (when (and (or jit-lock-stealth-timer jit-lock-defer-timer
260 jit-lock-context-timer)
261 ;; Only if there's no other buffer using them.
262 (not (catch 'found
263 (dolist (buf (buffer-list))
264 (with-current-buffer buf
265 (when jit-lock-mode (throw 'found t)))))))
266 (when jit-lock-stealth-timer
267 (cancel-timer jit-lock-stealth-timer)
268 (setq jit-lock-stealth-timer nil))
269 (when jit-lock-context-timer
270 (cancel-timer jit-lock-context-timer)
271 (setq jit-lock-context-timer nil))
272 (when jit-lock-defer-timer
273 (cancel-timer jit-lock-defer-timer)
274 (setq jit-lock-defer-timer nil)))
276 ;; Remove hooks.
277 (remove-hook 'after-change-functions 'jit-lock-after-change t)
278 (remove-hook 'fontification-functions 'jit-lock-function))))
280 (defun jit-lock-register (fun &optional contextual)
281 "Register FUN as a fontification function to be called in this buffer.
282 FUN will be called with two arguments START and END indicating the region
283 that needs to be (re)fontified.
284 If non-nil, CONTEXTUAL means that a contextual fontification would be useful."
285 (add-hook 'jit-lock-functions fun nil t)
286 (when (and contextual jit-lock-contextually)
287 (set (make-local-variable 'jit-lock-contextually) t))
288 (jit-lock-mode t))
290 (defun jit-lock-unregister (fun)
291 "Unregister FUN as a fontification function.
292 Only applies to the current buffer."
293 (remove-hook 'jit-lock-functions fun t)
294 (unless jit-lock-functions (jit-lock-mode nil)))
296 ;; This function is used to prevent font-lock-fontify-buffer from
297 ;; fontifying eagerly the whole buffer. This is important for
298 ;; things like CWarn mode which adds/removes a few keywords and
299 ;; does a refontify (which takes ages on large files).
300 (defun jit-lock-refontify (&optional beg end)
301 "Force refontification of the region BEG..END (default whole buffer)."
302 (with-buffer-prepared-for-jit-lock
303 (save-restriction
304 (widen)
305 (put-text-property (or beg (point-min)) (or end (point-max))
306 'fontified nil))))
308 ;;; On demand fontification.
310 (defun jit-lock-function (start)
311 "Fontify current buffer starting at position START.
312 This function is added to `fontification-functions' when `jit-lock-mode'
313 is active."
314 (when (and jit-lock-mode (not memory-full))
315 (if (null jit-lock-defer-timer)
316 ;; No deferral.
317 (jit-lock-fontify-now start (+ start jit-lock-chunk-size))
318 ;; Record the buffer for later fontification.
319 (unless (memq (current-buffer) jit-lock-defer-buffers)
320 (push (current-buffer) jit-lock-defer-buffers))
321 ;; Mark the area as defer-fontified so that the redisplay engine
322 ;; is happy and so that the idle timer can find the places to fontify.
323 (with-buffer-prepared-for-jit-lock
324 (put-text-property start
325 (next-single-property-change
326 start 'fontified nil
327 (min (point-max) (+ start jit-lock-chunk-size)))
328 'fontified 'defer)))))
330 (defun jit-lock-fontify-now (&optional start end)
331 "Fontify current buffer from START to END.
332 Defaults to the whole buffer. END can be out of bounds."
333 (with-buffer-prepared-for-jit-lock
334 (save-excursion
335 (unless start (setq start (point-min)))
336 (setq end (if end (min end (point-max)) (point-max)))
337 ;; This did bind `font-lock-beginning-of-syntax-function' to
338 ;; nil at some point, for an unknown reason. Don't do this; it
339 ;; can make highlighting slow due to expensive calls to
340 ;; `parse-partial-sexp' in function
341 ;; `font-lock-fontify-syntactically-region'. Example: paging
342 ;; from the end of a buffer to its start, can do repeated
343 ;; `parse-partial-sexp' starting from `point-min', which can
344 ;; take a long time in a large buffer.
345 (let ((orig-start start) next)
346 (save-match-data
347 ;; Fontify chunks beginning at START. The end of a
348 ;; chunk is either `end', or the start of a region
349 ;; before `end' that has already been fontified.
350 (while (and start (< start end))
351 ;; Determine the end of this chunk.
352 (setq next (or (text-property-any start end 'fontified t)
353 end))
355 ;; Decide which range of text should be fontified.
356 ;; The problem is that START and NEXT may be in the
357 ;; middle of something matched by a font-lock regexp.
358 ;; Until someone has a better idea, let's start
359 ;; at the start of the line containing START and
360 ;; stop at the start of the line following NEXT.
361 (goto-char next) (setq next (line-beginning-position 2))
362 (goto-char start) (setq start (line-beginning-position))
364 ;; Make sure the contextual refontification doesn't re-refontify
365 ;; what's already been refontified.
366 (when (and jit-lock-context-unfontify-pos
367 (< jit-lock-context-unfontify-pos next)
368 (>= jit-lock-context-unfontify-pos start)
369 ;; Don't move boundary forward if we have to
370 ;; refontify previous text. Otherwise, we risk moving
371 ;; it past the end of the multiline property and thus
372 ;; forget about this multiline region altogether.
373 (not (get-text-property start 'jit-lock-defer-multiline)))
374 (setq jit-lock-context-unfontify-pos next))
376 ;; Fontify the chunk, and mark it as fontified.
377 ;; We mark it first, to make sure that we don't indefinitely
378 ;; re-execute this fontification if an error occurs.
379 (put-text-property start next 'fontified t)
380 (condition-case err
381 (run-hook-with-args 'jit-lock-functions start next)
382 ;; If the user quits (which shouldn't happen in normal on-the-fly
383 ;; jit-locking), make sure the fontification will be performed
384 ;; before displaying the block again.
385 (quit (put-text-property start next 'fontified nil)
386 (funcall 'signal (car err) (cdr err))))
388 ;; The redisplay engine has already rendered the buffer up-to
389 ;; `orig-start' and won't notice if the above jit-lock-functions
390 ;; changed the appearance of any part of the buffer prior
391 ;; to that. So if `start' is before `orig-start', we need to
392 ;; cause a new redisplay cycle after this one so that any changes
393 ;; are properly reflected on screen.
394 ;; To make such repeated redisplay happen less often, we can
395 ;; eagerly extend the refontified region with
396 ;; jit-lock-after-change-extend-region-functions.
397 (when (< start orig-start)
398 (run-with-timer 0 nil 'jit-lock-force-redisplay
399 (current-buffer) start orig-start))
401 ;; Find the start of the next chunk, if any.
402 (setq start (text-property-any next end 'fontified nil))))))))
404 (defun jit-lock-force-redisplay (buf start end)
405 "Force the display engine to re-render buffer BUF from START to END."
406 (with-current-buffer buf
407 (with-buffer-prepared-for-jit-lock
408 ;; Don't cause refontification (it's already been done), but just do
409 ;; some random buffer change, so as to force redisplay.
410 (put-text-property start end 'fontified t))))
414 ;;; Stealth fontification.
416 (defsubst jit-lock-stealth-chunk-start (around)
417 "Return the start of the next chunk to fontify around position AROUND..
418 Value is nil if there is nothing more to fontify."
419 (if (zerop (buffer-size))
421 (save-restriction
422 (widen)
423 (let* ((next (text-property-not-all around (point-max) 'fontified t))
424 (prev (previous-single-property-change around 'fontified))
425 (prop (get-text-property (max (point-min) (1- around))
426 'fontified))
427 (start (cond
428 ((null prev)
429 ;; There is no property change between AROUND
430 ;; and the start of the buffer. If PROP is
431 ;; non-nil, everything in front of AROUND is
432 ;; fontified, otherwise nothing is fontified.
433 (if (eq prop t)
435 (max (point-min)
436 (- around (/ jit-lock-chunk-size 2)))))
437 ((eq prop t)
438 ;; PREV is the start of a region of fontified
439 ;; text containing AROUND. Start fontifying a
440 ;; chunk size before the end of the unfontified
441 ;; region in front of that.
442 (max (or (previous-single-property-change prev 'fontified)
443 (point-min))
444 (- prev jit-lock-chunk-size)))
446 ;; PREV is the start of a region of unfontified
447 ;; text containing AROUND. Start at PREV or
448 ;; chunk size in front of AROUND, whichever is
449 ;; nearer.
450 (max prev (- around jit-lock-chunk-size)))))
451 (result (cond ((null start) next)
452 ((null next) start)
453 ((< (- around start) (- next around)) start)
454 (t next))))
455 result))))
457 (defun jit-lock-stealth-fontify (&optional repeat)
458 "Fontify buffers stealthily.
459 This function is called repeatedly after Emacs has become idle for
460 `jit-lock-stealth-time' seconds. Optional argument REPEAT is expected
461 non-nil in a repeated invocation of this function."
462 ;; Cancel timer for repeated invocations.
463 (unless repeat
464 (cancel-timer jit-lock-stealth-repeat-timer))
465 (unless (or executing-kbd-macro
466 memory-full
467 (window-minibuffer-p (selected-window))
468 ;; For first invocation set up `jit-lock-stealth-buffers'.
469 ;; In repeated invocations it's already been set up.
470 (null (if repeat
471 jit-lock-stealth-buffers
472 (setq jit-lock-stealth-buffers (buffer-list)))))
473 (let ((buffer (car jit-lock-stealth-buffers))
474 (delay 0)
475 minibuffer-auto-raise
476 message-log-max
477 start)
478 (if (and jit-lock-stealth-load
479 (> (car (load-average)) jit-lock-stealth-load))
480 ;; Wait a little if load is too high.
481 (setq delay jit-lock-stealth-time)
482 (if (buffer-live-p buffer)
483 (with-current-buffer buffer
484 (if (and jit-lock-mode
485 (setq start (jit-lock-stealth-chunk-start (point))))
486 ;; Fontify one block of at most `jit-lock-chunk-size'
487 ;; characters.
488 (with-temp-message (if jit-lock-stealth-verbose
489 (concat "JIT stealth lock "
490 (buffer-name)))
491 (jit-lock-fontify-now start
492 (+ start jit-lock-chunk-size))
493 ;; Run again after `jit-lock-stealth-nice' seconds.
494 (setq delay (or jit-lock-stealth-nice 0)))
495 ;; Nothing to fontify here. Remove this buffer from
496 ;; `jit-lock-stealth-buffers' and run again immediately.
497 (setq jit-lock-stealth-buffers (cdr jit-lock-stealth-buffers))))
498 ;; Buffer is no longer live. Remove it from
499 ;; `jit-lock-stealth-buffers' and run again immediately.
500 (setq jit-lock-stealth-buffers (cdr jit-lock-stealth-buffers))))
501 ;; Call us again.
502 (when jit-lock-stealth-buffers
503 (timer-set-idle-time jit-lock-stealth-repeat-timer (current-idle-time))
504 (timer-inc-time jit-lock-stealth-repeat-timer delay)
505 (timer-activate-when-idle jit-lock-stealth-repeat-timer t)))))
508 ;;; Deferred fontification.
510 (defun jit-lock-deferred-fontify ()
511 "Fontify what was deferred."
512 (when (and jit-lock-defer-buffers (not memory-full))
513 ;; Mark the deferred regions back to `fontified = nil'
514 (dolist (buffer jit-lock-defer-buffers)
515 (when (buffer-live-p buffer)
516 (with-current-buffer buffer
517 ;; (message "Jit-Defer %s" (buffer-name))
518 (with-buffer-prepared-for-jit-lock
519 (let ((pos (point-min)))
520 (while
521 (progn
522 (when (eq (get-text-property pos 'fontified) 'defer)
523 (put-text-property
524 pos (setq pos (next-single-property-change
525 pos 'fontified nil (point-max)))
526 'fontified nil))
527 (setq pos (next-single-property-change pos 'fontified)))))))))
528 (setq jit-lock-defer-buffers nil)
529 ;; Force fontification of the visible parts.
530 (let ((jit-lock-defer-timer nil))
531 ;; (message "Jit-Defer Now")
532 (sit-for 0)
533 ;; (message "Jit-Defer Done")
537 (defun jit-lock-context-fontify ()
538 "Refresh fontification to take new context into account."
539 (unless memory-full
540 (dolist (buffer (buffer-list))
541 (with-current-buffer buffer
542 (when jit-lock-context-unfontify-pos
543 ;; (message "Jit-Context %s" (buffer-name))
544 (save-restriction
545 (widen)
546 (when (and (>= jit-lock-context-unfontify-pos (point-min))
547 (< jit-lock-context-unfontify-pos (point-max)))
548 ;; If we're in text that matches a complex multi-line
549 ;; font-lock pattern, make sure the whole text will be
550 ;; redisplayed eventually.
551 ;; Despite its name, we treat jit-lock-defer-multiline here
552 ;; rather than in jit-lock-defer since it has to do with multiple
553 ;; lines, i.e. with context.
554 (when (get-text-property jit-lock-context-unfontify-pos
555 'jit-lock-defer-multiline)
556 (setq jit-lock-context-unfontify-pos
557 (or (previous-single-property-change
558 jit-lock-context-unfontify-pos
559 'jit-lock-defer-multiline)
560 (point-min))))
561 (with-buffer-prepared-for-jit-lock
562 ;; Force contextual refontification.
563 (remove-text-properties
564 jit-lock-context-unfontify-pos (point-max)
565 '(fontified nil jit-lock-defer-multiline nil)))
566 (setq jit-lock-context-unfontify-pos (point-max)))))))))
568 (defvar jit-lock-start) (defvar jit-lock-end) ; Dynamically scoped variables.
569 (defvar jit-lock-after-change-extend-region-functions nil
570 "Hook that can extend the text to refontify after a change.
571 This is run after every buffer change. The functions are called with
572 the three arguments of `after-change-functions': START END OLD-LEN.
573 The extended region to refontify is returned indirectly by modifying
574 the variables `jit-lock-start' and `jit-lock-end'.
576 Note that extending the region this way is not strictly necessary, except
577 that the nature of the redisplay code tends to otherwise leave some of
578 the rehighlighted text displayed with the old highlight until the next
579 redisplay (see comment about repeated redisplay in `jit-lock-fontify-now').")
581 (defun jit-lock-after-change (start end old-len)
582 "Mark the rest of the buffer as not fontified after a change.
583 Installed on `after-change-functions'.
584 START and END are the start and end of the changed text. OLD-LEN
585 is the pre-change length.
586 This function ensures that lines following the change will be refontified
587 in case the syntax of those lines has changed. Refontification
588 will take place when text is fontified stealthily."
589 (when (and jit-lock-mode (not memory-full))
590 (let ((jit-lock-start start)
591 (jit-lock-end end))
592 (with-buffer-prepared-for-jit-lock
593 (run-hook-with-args 'jit-lock-after-change-extend-region-functions
594 start end old-len)
595 ;; Make sure we change at least one char (in case of deletions).
596 (setq jit-lock-end (min (max jit-lock-end (1+ start)) (point-max)))
597 ;; Request refontification.
598 (put-text-property jit-lock-start jit-lock-end 'fontified nil))
599 ;; Mark the change for deferred contextual refontification.
600 (when jit-lock-context-unfontify-pos
601 (setq jit-lock-context-unfontify-pos
602 ;; Here we use `start' because nothing guarantees that the
603 ;; text between start and end will be otherwise refontified:
604 ;; usually it will be refontified by virtue of being
605 ;; displayed, but if it's outside of any displayed area in the
606 ;; buffer, only jit-lock-context-* will re-fontify it.
607 (min jit-lock-context-unfontify-pos jit-lock-start))))))
609 (provide 'jit-lock)
611 ;; arch-tag: 56b5de6e-f581-453b-bb97-49c39372ff9e
612 ;;; jit-lock.el ends here