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e8af40ee | 1 | ;;; jit-lock.el --- just-in-time fontification |
7840ced1 | 2 | |
cd9b540f | 3 | ;; Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc. |
7840ced1 GM |
4 | |
5 | ;; Author: Gerd Moellmann <gerd@gnu.org> | |
6 | ;; Keywords: faces files | |
7840ced1 GM |
7 | |
8 | ;; This file is part of GNU Emacs. | |
9 | ||
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 2, or (at your option) | |
13 | ;; any later version. | |
14 | ||
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. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
24 | ||
25 | ;;; Commentary: | |
26 | ||
27 | ;; Just-in-time fontification, triggered by C redisplay code. | |
28 | ||
29 | ;;; Code: | |
30 | ||
31 | ||
7840ced1 | 32 | (eval-when-compile |
60bffb78 GM |
33 | (defmacro with-buffer-unmodified (&rest body) |
34 | "Eval BODY, preserving the current buffer's modified state." | |
35 | (let ((modified (make-symbol "modified"))) | |
36 | `(let ((,modified (buffer-modified-p))) | |
be390cb3 SM |
37 | (unwind-protect |
38 | (progn ,@body) | |
39 | (unless ,modified | |
40 | (restore-buffer-modified-p nil)))))) | |
60bffb78 | 41 | |
bcacade9 | 42 | (defmacro with-buffer-prepared-for-jit-lock (&rest body) |
7840ced1 GM |
43 | "Execute BODY in current buffer, overriding several variables. |
44 | Preserves the `buffer-modified-p' state of the current buffer." | |
9f1a8fb4 GM |
45 | `(with-buffer-unmodified |
46 | (let ((buffer-undo-list t) | |
47 | (inhibit-read-only t) | |
48 | (inhibit-point-motion-hooks t) | |
bcacade9 | 49 | (inhibit-modification-hooks t) |
9f1a8fb4 GM |
50 | deactivate-mark |
51 | buffer-file-name | |
52 | buffer-file-truename) | |
53 | ,@body)))) | |
7840ced1 | 54 | |
60bffb78 | 55 | |
7840ced1 GM |
56 | \f |
57 | ;;; Customization. | |
58 | ||
59 | (defcustom jit-lock-chunk-size 500 | |
bcacade9 | 60 | "*Jit-lock chunks of this many characters, or smaller." |
7840ced1 GM |
61 | :type 'integer |
62 | :group 'jit-lock) | |
63 | ||
64 | ||
65 | (defcustom jit-lock-stealth-time 3 | |
66 | "*Time in seconds to wait before beginning stealth fontification. | |
67 | Stealth fontification occurs if there is no input within this time. | |
f86292a9 | 68 | If nil, stealth fontification is never performed. |
7840ced1 GM |
69 | |
70 | The value of this variable is used when JIT Lock mode is turned on." | |
71 | :type '(choice (const :tag "never" nil) | |
72 | (number :tag "seconds")) | |
73 | :group 'jit-lock) | |
74 | ||
75 | ||
76 | (defcustom jit-lock-stealth-nice 0.125 | |
77 | "*Time in seconds to pause between chunks of stealth fontification. | |
78 | Each iteration of stealth fontification is separated by this amount of time, | |
79 | thus reducing the demand that stealth fontification makes on the system. | |
80 | If nil, means stealth fontification is never paused. | |
81 | To reduce machine load during stealth fontification, at the cost of stealth | |
82 | taking longer to fontify, you could increase the value of this variable. | |
83 | See also `jit-lock-stealth-load'." | |
84 | :type '(choice (const :tag "never" nil) | |
85 | (number :tag "seconds")) | |
86 | :group 'jit-lock) | |
87 | ||
88 | ||
89 | (defcustom jit-lock-stealth-load | |
90 | (if (condition-case nil (load-average) (error)) 200) | |
91 | "*Load in percentage above which stealth fontification is suspended. | |
92 | Stealth fontification pauses when the system short-term load average (as | |
93 | returned by the function `load-average' if supported) goes above this level, | |
94 | thus reducing the demand that stealth fontification makes on the system. | |
95 | If nil, means stealth fontification is never suspended. | |
96 | To reduce machine load during stealth fontification, at the cost of stealth | |
97 | taking longer to fontify, you could reduce the value of this variable. | |
98 | See also `jit-lock-stealth-nice'." | |
99 | :type (if (condition-case nil (load-average) (error)) | |
100 | '(choice (const :tag "never" nil) | |
101 | (integer :tag "load")) | |
102 | '(const :format "%t: unsupported\n" nil)) | |
103 | :group 'jit-lock) | |
104 | ||
105 | ||
106 | (defcustom jit-lock-stealth-verbose nil | |
107 | "*If non-nil, means stealth fontification should show status messages." | |
108 | :type 'boolean | |
109 | :group 'jit-lock) | |
110 | ||
111 | ||
112 | (defcustom jit-lock-defer-contextually 'syntax-driven | |
113 | "*If non-nil, means deferred fontification should be syntactically true. | |
114 | If nil, means deferred fontification occurs only on those lines modified. This | |
115 | means where modification on a line causes syntactic change on subsequent lines, | |
116 | those subsequent lines are not refontified to reflect their new context. | |
117 | If t, means deferred fontification occurs on those lines modified and all | |
118 | subsequent lines. This means those subsequent lines are refontified to reflect | |
119 | their new syntactic context, either immediately or when scrolling into them. | |
120 | If any other value, e.g., `syntax-driven', means deferred syntactically true | |
121 | fontification occurs only if syntactic fontification is performed using the | |
122 | buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil. | |
123 | ||
124 | The value of this variable is used when JIT Lock mode is turned on." | |
125 | :type '(choice (const :tag "never" nil) | |
126 | (const :tag "always" t) | |
127 | (other :tag "syntax-driven" syntax-driven)) | |
128 | :group 'jit-lock) | |
129 | ||
130 | ||
131 | \f | |
132 | ;;; Variables that are not customizable. | |
133 | ||
134 | (defvar jit-lock-mode nil | |
135 | "Non-nil means Just-in-time Lock mode is active.") | |
136 | (make-variable-buffer-local 'jit-lock-mode) | |
137 | ||
be390cb3 SM |
138 | (defvar jit-lock-functions nil |
139 | "Functions to do the actual fontification. | |
140 | They are called with two arguments: the START and END of the region to fontify.") | |
a62e3c6f | 141 | (make-variable-buffer-local 'jit-lock-functions) |
7840ced1 GM |
142 | |
143 | (defvar jit-lock-first-unfontify-pos nil | |
a62e3c6f | 144 | "Consider text after this position as contextually unfontified. |
bcacade9 | 145 | If nil, contextual fontification is disabled.") |
7840ced1 GM |
146 | (make-variable-buffer-local 'jit-lock-first-unfontify-pos) |
147 | ||
148 | ||
149 | (defvar jit-lock-stealth-timer nil | |
150 | "Timer for stealth fontification in Just-in-time Lock mode.") | |
7840ced1 GM |
151 | \f |
152 | ;;; JIT lock mode | |
153 | ||
7840ced1 GM |
154 | (defun jit-lock-mode (arg) |
155 | "Toggle Just-in-time Lock mode. | |
bcacade9 | 156 | Turn Just-in-time Lock mode on if and only if ARG is non-nil. |
7840ced1 GM |
157 | Enable it automatically by customizing group `font-lock'. |
158 | ||
159 | When Just-in-time Lock mode is enabled, fontification is different in the | |
160 | following ways: | |
161 | ||
162 | - Demand-driven buffer fontification triggered by Emacs C code. | |
163 | This means initial fontification of the whole buffer does not occur. | |
164 | Instead, fontification occurs when necessary, such as when scrolling | |
165 | through the buffer would otherwise reveal unfontified areas. This is | |
166 | useful if buffer fontification is too slow for large buffers. | |
167 | ||
168 | - Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil. | |
169 | This means remaining unfontified areas of buffers are fontified if Emacs has | |
170 | been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle. | |
171 | This is useful if any buffer has any deferred fontification. | |
172 | ||
173 | - Deferred context fontification if `jit-lock-defer-contextually' is | |
174 | non-nil. This means fontification updates the buffer corresponding to | |
175 | true syntactic context, after `jit-lock-stealth-time' seconds of Emacs | |
176 | idle time, while Emacs remains idle. Otherwise, fontification occurs | |
177 | on modified lines only, and subsequent lines can remain fontified | |
178 | corresponding to previous syntactic contexts. This is useful where | |
179 | strings or comments span lines. | |
180 | ||
181 | Stealth fontification only occurs while the system remains unloaded. | |
182 | If the system load rises above `jit-lock-stealth-load' percent, stealth | |
183 | fontification is suspended. Stealth fontification intensity is controlled via | |
02b420eb | 184 | the variable `jit-lock-stealth-nice'." |
bcacade9 SM |
185 | (setq jit-lock-mode arg) |
186 | (cond (;; Turn Just-in-time Lock mode on. | |
187 | jit-lock-mode | |
188 | ||
a62e3c6f SM |
189 | ;; Mark the buffer for refontification |
190 | (jit-lock-refontify) | |
02b420eb | 191 | |
7840ced1 | 192 | ;; Install an idle timer for stealth fontification. |
c94d5f40 | 193 | (when (and jit-lock-stealth-time (null jit-lock-stealth-timer)) |
02b420eb | 194 | (setq jit-lock-stealth-timer |
7840ced1 GM |
195 | (run-with-idle-timer jit-lock-stealth-time |
196 | jit-lock-stealth-time | |
197 | 'jit-lock-stealth-fontify))) | |
198 | ||
bcacade9 | 199 | ;; Initialize deferred contextual fontification if requested. |
a62e3c6f | 200 | (when (eq jit-lock-defer-contextually t) |
c94d5f40 SM |
201 | (setq jit-lock-first-unfontify-pos |
202 | (or jit-lock-first-unfontify-pos (point-max)))) | |
bcacade9 | 203 | |
a62e3c6f | 204 | ;; Setup our hooks. |
bcacade9 | 205 | (add-hook 'after-change-functions 'jit-lock-after-change nil t) |
7840ced1 GM |
206 | (add-hook 'fontification-functions 'jit-lock-function)) |
207 | ||
208 | ;; Turn Just-in-time Lock mode off. | |
209 | (t | |
210 | ;; Cancel our idle timer. | |
211 | (when jit-lock-stealth-timer | |
212 | (cancel-timer jit-lock-stealth-timer) | |
213 | (setq jit-lock-stealth-timer nil)) | |
214 | ||
a62e3c6f | 215 | ;; Remove hooks. |
02b420eb | 216 | (remove-hook 'after-change-functions 'jit-lock-after-change t) |
7840ced1 GM |
217 | (remove-hook 'fontification-functions 'jit-lock-function)))) |
218 | ||
c94d5f40 SM |
219 | ;;;###autoload |
220 | (defun jit-lock-register (fun &optional contextual) | |
8a677d4f SM |
221 | "Register FUN as a fontification function to be called in this buffer. |
222 | FUN will be called with two arguments START and END indicating the region | |
c94d5f40 SM |
223 | that needs to be (re)fontified. |
224 | If non-nil, CONTEXTUAL means that a contextual fontification would be useful." | |
f8bacc70 | 225 | (add-hook 'jit-lock-functions fun nil t) |
c94d5f40 SM |
226 | (when (and contextual jit-lock-defer-contextually) |
227 | (set (make-local-variable 'jit-lock-defer-contextually) t)) | |
f8bacc70 SM |
228 | (jit-lock-mode t)) |
229 | ||
230 | (defun jit-lock-unregister (fun) | |
8a677d4f | 231 | "Unregister FUN as a fontification function. |
f8bacc70 SM |
232 | Only applies to the current buffer." |
233 | (remove-hook 'jit-lock-functions fun t) | |
a62e3c6f | 234 | (unless jit-lock-functions (jit-lock-mode nil))) |
7840ced1 | 235 | |
02b420eb SM |
236 | ;; This function is used to prevent font-lock-fontify-buffer from |
237 | ;; fontifying eagerly the whole buffer. This is important for | |
238 | ;; things like CWarn mode which adds/removes a few keywords and | |
239 | ;; does a refontify (which takes ages on large files). | |
a62e3c6f SM |
240 | (defun jit-lock-refontify (&optional beg end) |
241 | "Force refontification of the region BEG..END (default whole buffer)." | |
bcacade9 | 242 | (with-buffer-prepared-for-jit-lock |
5a5987eb SM |
243 | (save-restriction |
244 | (widen) | |
a62e3c6f SM |
245 | (add-text-properties (or beg (point-min)) (or end (point-max)) |
246 | '(fontified nil))))) | |
7840ced1 GM |
247 | \f |
248 | ;;; On demand fontification. | |
249 | ||
250 | (defun jit-lock-function (start) | |
251 | "Fontify current buffer starting at position START. | |
252 | This function is added to `fontification-functions' when `jit-lock-mode' | |
253 | is active." | |
254 | (when jit-lock-mode | |
a62e3c6f | 255 | (jit-lock-fontify-now start (+ start jit-lock-chunk-size)))) |
60bffb78 | 256 | |
a62e3c6f SM |
257 | |
258 | (defun jit-lock-fontify-now (&optional start end) | |
259 | "Fontify current buffer from START to END. | |
260 | Defaults to the whole buffer. END can be out of bounds." | |
bcacade9 | 261 | (with-buffer-prepared-for-jit-lock |
60bffb78 GM |
262 | (save-excursion |
263 | (save-restriction | |
264 | (widen) | |
a62e3c6f SM |
265 | (unless start (setq start (point-min))) |
266 | (setq end (if end (min end (point-max)) (point-max))) | |
9724173b GM |
267 | ;; This did bind `font-lock-beginning-of-syntax-function' to |
268 | ;; nil at some point, for an unknown reason. Don't do this; it | |
269 | ;; can make highlighting slow due to expensive calls to | |
270 | ;; `parse-partial-sexp' in function | |
271 | ;; `font-lock-fontify-syntactically-region'. Example: paging | |
272 | ;; from the end of a buffer to its start, can do repeated | |
273 | ;; `parse-partial-sexp' starting from `point-min', which can | |
274 | ;; take a long time in a large buffer. | |
275 | (let (next) | |
60bffb78 | 276 | (save-match-data |
be390cb3 SM |
277 | ;; Fontify chunks beginning at START. The end of a |
278 | ;; chunk is either `end', or the start of a region | |
279 | ;; before `end' that has already been fontified. | |
280 | (while start | |
281 | ;; Determine the end of this chunk. | |
282 | (setq next (or (text-property-any start end 'fontified t) | |
283 | end)) | |
284 | ||
285 | ;; Decide which range of text should be fontified. | |
286 | ;; The problem is that START and NEXT may be in the | |
287 | ;; middle of something matched by a font-lock regexp. | |
288 | ;; Until someone has a better idea, let's start | |
289 | ;; at the start of the line containing START and | |
290 | ;; stop at the start of the line following NEXT. | |
a62e3c6f SM |
291 | (goto-char next) (setq next (line-beginning-position 2)) |
292 | (goto-char start) (setq start (line-beginning-position)) | |
293 | ||
be390cb3 SM |
294 | ;; Fontify the chunk, and mark it as fontified. |
295 | ;; We mark it first, to make sure that we don't indefinitely | |
296 | ;; re-execute this fontification if an error occurs. | |
297 | (add-text-properties start next '(fontified t)) | |
a62e3c6f | 298 | (run-hook-with-args 'jit-lock-functions start next) |
7840ced1 | 299 | |
be390cb3 SM |
300 | ;; Find the start of the next chunk, if any. |
301 | (setq start (text-property-any next end 'fontified nil))))))))) | |
7840ced1 | 302 | |
7840ced1 GM |
303 | \f |
304 | ;;; Stealth fontification. | |
305 | ||
306 | (defsubst jit-lock-stealth-chunk-start (around) | |
307 | "Return the start of the next chunk to fontify around position AROUND.. | |
308 | Value is nil if there is nothing more to fontify." | |
8c887c51 GM |
309 | (if (zerop (buffer-size)) |
310 | nil | |
311 | (save-restriction | |
312 | (widen) | |
313 | (let* ((next (text-property-any around (point-max) 'fontified nil)) | |
314 | (prev (previous-single-property-change around 'fontified)) | |
315 | (prop (get-text-property (max (point-min) (1- around)) | |
316 | 'fontified)) | |
317 | (start (cond | |
318 | ((null prev) | |
319 | ;; There is no property change between AROUND | |
320 | ;; and the start of the buffer. If PROP is | |
321 | ;; non-nil, everything in front of AROUND is | |
322 | ;; fontified, otherwise nothing is fontified. | |
323 | (if prop | |
324 | nil | |
325 | (max (point-min) | |
326 | (- around (/ jit-lock-chunk-size 2))))) | |
327 | (prop | |
328 | ;; PREV is the start of a region of fontified | |
bcacade9 | 329 | ;; text containing AROUND. Start fontifying a |
8c887c51 GM |
330 | ;; chunk size before the end of the unfontified |
331 | ;; region in front of that. | |
332 | (max (or (previous-single-property-change prev 'fontified) | |
333 | (point-min)) | |
334 | (- prev jit-lock-chunk-size))) | |
335 | (t | |
336 | ;; PREV is the start of a region of unfontified | |
337 | ;; text containing AROUND. Start at PREV or | |
338 | ;; chunk size in front of AROUND, whichever is | |
339 | ;; nearer. | |
340 | (max prev (- around jit-lock-chunk-size))))) | |
341 | (result (cond ((null start) next) | |
342 | ((null next) start) | |
343 | ((< (- around start) (- next around)) start) | |
344 | (t next)))) | |
345 | result)))) | |
346 | ||
7840ced1 GM |
347 | |
348 | (defun jit-lock-stealth-fontify () | |
349 | "Fontify buffers stealthily. | |
350 | This functions is called after Emacs has been idle for | |
351 | `jit-lock-stealth-time' seconds." | |
352 | (unless (or executing-kbd-macro | |
353 | (window-minibuffer-p (selected-window))) | |
354 | (let ((buffers (buffer-list)) | |
355 | minibuffer-auto-raise | |
356 | message-log-max) | |
8c887c51 | 357 | (while (and buffers (not (input-pending-p))) |
7840ced1 GM |
358 | (let ((buffer (car buffers))) |
359 | (setq buffers (cdr buffers)) | |
8c887c51 | 360 | |
7840ced1 GM |
361 | (with-current-buffer buffer |
362 | (when jit-lock-mode | |
363 | ;; This is funny. Calling sit-for with 3rd arg non-nil | |
364 | ;; so that it doesn't redisplay, internally calls | |
365 | ;; wait_reading_process_input also with a parameter | |
366 | ;; saying "don't redisplay." Since this function here | |
367 | ;; is called periodically, this effectively leads to | |
368 | ;; process output not being redisplayed at all because | |
369 | ;; redisplay_internal is never called. (That didn't | |
370 | ;; work in the old redisplay either.) So, we learn that | |
371 | ;; we mustn't call sit-for that way here. But then, we | |
372 | ;; have to be cautious not to call sit-for in a widened | |
373 | ;; buffer, since this could display hidden parts of that | |
374 | ;; buffer. This explains the seemingly weird use of | |
375 | ;; save-restriction/widen here. | |
376 | ||
377 | (with-temp-message (if jit-lock-stealth-verbose | |
378 | (concat "JIT stealth lock " | |
379 | (buffer-name))) | |
8c887c51 | 380 | |
9f1a8fb4 GM |
381 | ;; Perform deferred unfontification, if any. |
382 | (when jit-lock-first-unfontify-pos | |
383 | (save-restriction | |
384 | (widen) | |
385 | (when (and (>= jit-lock-first-unfontify-pos (point-min)) | |
386 | (< jit-lock-first-unfontify-pos (point-max))) | |
bcacade9 | 387 | (with-buffer-prepared-for-jit-lock |
9f1a8fb4 GM |
388 | (put-text-property jit-lock-first-unfontify-pos |
389 | (point-max) 'fontified nil)) | |
bcacade9 | 390 | (setq jit-lock-first-unfontify-pos (point-max))))) |
9f1a8fb4 GM |
391 | |
392 | ;; In the following code, the `sit-for' calls cause a | |
393 | ;; redisplay, so it's required that the | |
394 | ;; buffer-modified flag of a buffer that is displayed | |
395 | ;; has the right value---otherwise the mode line of | |
396 | ;; an unmodified buffer would show a `*'. | |
397 | (let (start | |
398 | (nice (or jit-lock-stealth-nice 0)) | |
399 | (point (point))) | |
400 | (while (and (setq start | |
401 | (jit-lock-stealth-chunk-start point)) | |
402 | (sit-for nice)) | |
7840ced1 | 403 | |
9f1a8fb4 GM |
404 | ;; Wait a little if load is too high. |
405 | (when (and jit-lock-stealth-load | |
406 | (> (car (load-average)) jit-lock-stealth-load)) | |
407 | (sit-for (or jit-lock-stealth-time 30))) | |
7840ced1 | 408 | |
9f1a8fb4 GM |
409 | ;; Unless there's input pending now, fontify. |
410 | (unless (input-pending-p) | |
a62e3c6f SM |
411 | (jit-lock-fontify-now |
412 | start (+ start jit-lock-chunk-size))))))))))))) | |
7840ced1 GM |
413 | |
414 | ||
415 | \f | |
416 | ;;; Deferred fontification. | |
417 | ||
418 | (defun jit-lock-after-change (start end old-len) | |
419 | "Mark the rest of the buffer as not fontified after a change. | |
420 | Installed on `after-change-functions'. | |
421 | START and END are the start and end of the changed text. OLD-LEN | |
422 | is the pre-change length. | |
423 | This function ensures that lines following the change will be refontified | |
424 | in case the syntax of those lines has changed. Refontification | |
425 | will take place when text is fontified stealthily." | |
7840ced1 | 426 | (when jit-lock-mode |
d9330f43 SM |
427 | (save-excursion |
428 | (with-buffer-prepared-for-jit-lock | |
429 | ;; It's important that the `fontified' property be set from the | |
430 | ;; beginning of the line, else font-lock will properly change the | |
431 | ;; text's face, but the display will have been done already and will | |
432 | ;; be inconsistent with the buffer's content. | |
433 | (goto-char start) | |
434 | (setq start (line-beginning-position)) | |
7a1e3cec | 435 | |
df22166e SM |
436 | ;; If we're in text that matches a multi-line font-lock pattern, |
437 | ;; make sure the whole text will be redisplayed. | |
438 | (when (get-text-property start 'font-lock-multiline) | |
439 | (setq start (or (previous-single-property-change | |
440 | start 'font-lock-multiline) | |
441 | (point-min)))) | |
442 | ||
d9330f43 SM |
443 | ;; Make sure we change at least one char (in case of deletions). |
444 | (setq end (min (max end (1+ start)) (point-max))) | |
445 | ;; Request refontification. | |
446 | (put-text-property start end 'fontified nil)) | |
447 | ;; Mark the change for deferred contextual refontification. | |
448 | (when jit-lock-first-unfontify-pos | |
449 | (setq jit-lock-first-unfontify-pos | |
450 | (min jit-lock-first-unfontify-pos start)))))) | |
7840ced1 | 451 | |
7840ced1 GM |
452 | (provide 'jit-lock) |
453 | ||
e8af40ee | 454 | ;;; jit-lock.el ends here |