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7840ced1 GM |
1 | ;;; jit-lock.el --- just-in-time fontification. |
2 | ||
3 | ;; Copyright (C) 1998 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Author: Gerd Moellmann <gerd@gnu.org> | |
6 | ;; Keywords: faces files | |
7 | ;; Version: 1.0 | |
8 | ||
9 | ;; This file is part of GNU Emacs. | |
10 | ||
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 2, or (at your option) | |
14 | ;; any later version. | |
15 | ||
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. | |
20 | ||
21 | ;; You should have received a copy of the GNU General Public License | |
22 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
23 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
24 | ;; Boston, MA 02111-1307, USA. | |
25 | ||
26 | ;;; Commentary: | |
27 | ||
28 | ;; Just-in-time fontification, triggered by C redisplay code. | |
29 | ||
30 | ;;; Code: | |
31 | ||
32 | ||
33 | (require 'font-lock) | |
34 | ||
35 | (eval-when-compile | |
60bffb78 GM |
36 | (defmacro with-buffer-unmodified (&rest body) |
37 | "Eval BODY, preserving the current buffer's modified state." | |
38 | (let ((modified (make-symbol "modified"))) | |
39 | `(let ((,modified (buffer-modified-p))) | |
40 | ,@body | |
25fbf2c4 GM |
41 | (unless ,modified |
42 | (restore-buffer-modified-p nil))))) | |
60bffb78 | 43 | |
bcacade9 | 44 | (defmacro with-buffer-prepared-for-jit-lock (&rest body) |
7840ced1 GM |
45 | "Execute BODY in current buffer, overriding several variables. |
46 | Preserves the `buffer-modified-p' state of the current buffer." | |
9f1a8fb4 GM |
47 | `(with-buffer-unmodified |
48 | (let ((buffer-undo-list t) | |
49 | (inhibit-read-only t) | |
50 | (inhibit-point-motion-hooks t) | |
bcacade9 | 51 | (inhibit-modification-hooks t) |
9f1a8fb4 GM |
52 | deactivate-mark |
53 | buffer-file-name | |
54 | buffer-file-truename) | |
55 | ,@body)))) | |
7840ced1 | 56 | |
60bffb78 | 57 | |
7840ced1 GM |
58 | \f |
59 | ;;; Customization. | |
60 | ||
61 | (defcustom jit-lock-chunk-size 500 | |
bcacade9 | 62 | "*Jit-lock chunks of this many characters, or smaller." |
7840ced1 GM |
63 | :type 'integer |
64 | :group 'jit-lock) | |
65 | ||
66 | ||
67 | (defcustom jit-lock-stealth-time 3 | |
68 | "*Time in seconds to wait before beginning stealth fontification. | |
69 | Stealth fontification occurs if there is no input within this time. | |
70 | If nil, means stealth fontification is never performed. | |
71 | ||
72 | The value of this variable is used when JIT Lock mode is turned on." | |
73 | :type '(choice (const :tag "never" nil) | |
74 | (number :tag "seconds")) | |
75 | :group 'jit-lock) | |
76 | ||
77 | ||
78 | (defcustom jit-lock-stealth-nice 0.125 | |
79 | "*Time in seconds to pause between chunks of stealth fontification. | |
80 | Each iteration of stealth fontification is separated by this amount of time, | |
81 | thus reducing the demand that stealth fontification makes on the system. | |
82 | If nil, means stealth fontification is never paused. | |
83 | To reduce machine load during stealth fontification, at the cost of stealth | |
84 | taking longer to fontify, you could increase the value of this variable. | |
85 | See also `jit-lock-stealth-load'." | |
86 | :type '(choice (const :tag "never" nil) | |
87 | (number :tag "seconds")) | |
88 | :group 'jit-lock) | |
89 | ||
90 | ||
91 | (defcustom jit-lock-stealth-load | |
92 | (if (condition-case nil (load-average) (error)) 200) | |
93 | "*Load in percentage above which stealth fontification is suspended. | |
94 | Stealth fontification pauses when the system short-term load average (as | |
95 | returned by the function `load-average' if supported) goes above this level, | |
96 | thus reducing the demand that stealth fontification makes on the system. | |
97 | If nil, means stealth fontification is never suspended. | |
98 | To reduce machine load during stealth fontification, at the cost of stealth | |
99 | taking longer to fontify, you could reduce the value of this variable. | |
100 | See also `jit-lock-stealth-nice'." | |
101 | :type (if (condition-case nil (load-average) (error)) | |
102 | '(choice (const :tag "never" nil) | |
103 | (integer :tag "load")) | |
104 | '(const :format "%t: unsupported\n" nil)) | |
105 | :group 'jit-lock) | |
106 | ||
107 | ||
108 | (defcustom jit-lock-stealth-verbose nil | |
109 | "*If non-nil, means stealth fontification should show status messages." | |
110 | :type 'boolean | |
111 | :group 'jit-lock) | |
112 | ||
113 | ||
114 | (defcustom jit-lock-defer-contextually 'syntax-driven | |
115 | "*If non-nil, means deferred fontification should be syntactically true. | |
116 | If nil, means deferred fontification occurs only on those lines modified. This | |
117 | means where modification on a line causes syntactic change on subsequent lines, | |
118 | those subsequent lines are not refontified to reflect their new context. | |
119 | If t, means deferred fontification occurs on those lines modified and all | |
120 | subsequent lines. This means those subsequent lines are refontified to reflect | |
121 | their new syntactic context, either immediately or when scrolling into them. | |
122 | If any other value, e.g., `syntax-driven', means deferred syntactically true | |
123 | fontification occurs only if syntactic fontification is performed using the | |
124 | buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil. | |
125 | ||
126 | The value of this variable is used when JIT Lock mode is turned on." | |
127 | :type '(choice (const :tag "never" nil) | |
128 | (const :tag "always" t) | |
129 | (other :tag "syntax-driven" syntax-driven)) | |
130 | :group 'jit-lock) | |
131 | ||
132 | ||
133 | \f | |
134 | ;;; Variables that are not customizable. | |
135 | ||
136 | (defvar jit-lock-mode nil | |
137 | "Non-nil means Just-in-time Lock mode is active.") | |
138 | (make-variable-buffer-local 'jit-lock-mode) | |
139 | ||
140 | ||
141 | (defvar jit-lock-first-unfontify-pos nil | |
bcacade9 SM |
142 | "Consider text after this position as unfontified. |
143 | If nil, contextual fontification is disabled.") | |
7840ced1 GM |
144 | (make-variable-buffer-local 'jit-lock-first-unfontify-pos) |
145 | ||
146 | ||
147 | (defvar jit-lock-stealth-timer nil | |
148 | "Timer for stealth fontification in Just-in-time Lock mode.") | |
149 | ||
02b420eb SM |
150 | (defvar jit-lock-saved-fontify-buffer-function nil |
151 | "Value of `font-lock-fontify-buffer-function' before jit-lock's activation.") | |
7840ced1 GM |
152 | |
153 | \f | |
154 | ;;; JIT lock mode | |
155 | ||
156 | ;;;###autoload | |
157 | (defun jit-lock-mode (arg) | |
158 | "Toggle Just-in-time Lock mode. | |
bcacade9 | 159 | Turn Just-in-time Lock mode on if and only if ARG is non-nil. |
7840ced1 GM |
160 | Enable it automatically by customizing group `font-lock'. |
161 | ||
162 | When Just-in-time Lock mode is enabled, fontification is different in the | |
163 | following ways: | |
164 | ||
165 | - Demand-driven buffer fontification triggered by Emacs C code. | |
166 | This means initial fontification of the whole buffer does not occur. | |
167 | Instead, fontification occurs when necessary, such as when scrolling | |
168 | through the buffer would otherwise reveal unfontified areas. This is | |
169 | useful if buffer fontification is too slow for large buffers. | |
170 | ||
171 | - Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil. | |
172 | This means remaining unfontified areas of buffers are fontified if Emacs has | |
173 | been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle. | |
174 | This is useful if any buffer has any deferred fontification. | |
175 | ||
176 | - Deferred context fontification if `jit-lock-defer-contextually' is | |
177 | non-nil. This means fontification updates the buffer corresponding to | |
178 | true syntactic context, after `jit-lock-stealth-time' seconds of Emacs | |
179 | idle time, while Emacs remains idle. Otherwise, fontification occurs | |
180 | on modified lines only, and subsequent lines can remain fontified | |
181 | corresponding to previous syntactic contexts. This is useful where | |
182 | strings or comments span lines. | |
183 | ||
184 | Stealth fontification only occurs while the system remains unloaded. | |
185 | If the system load rises above `jit-lock-stealth-load' percent, stealth | |
186 | fontification is suspended. Stealth fontification intensity is controlled via | |
02b420eb | 187 | the variable `jit-lock-stealth-nice'." |
bcacade9 SM |
188 | (setq jit-lock-mode arg) |
189 | (cond (;; Turn Just-in-time Lock mode on. | |
190 | jit-lock-mode | |
191 | ||
5a5987eb SM |
192 | ;; Mark the buffer for refontification |
193 | ;; (in case spurious `fontified' text-props were left around). | |
194 | (jit-lock-fontify-buffer) | |
195 | ||
7840ced1 GM |
196 | ;; Setting `font-lock-fontified' makes font-lock believe the |
197 | ;; buffer is already fontified, so that it won't highlight | |
02b420eb | 198 | ;; the whole buffer or bail out on a large buffer. |
5a5987eb | 199 | (set (make-local-variable 'font-lock-fontified) t) |
7840ced1 | 200 | |
02b420eb SM |
201 | ;; Setup JIT font-lock-fontify-buffer. |
202 | (unless jit-lock-saved-fontify-buffer-function | |
203 | (set (make-local-variable 'jit-lock-saved-fontify-buffer-function) | |
204 | font-lock-fontify-buffer-function) | |
205 | (set (make-local-variable 'font-lock-fontify-buffer-function) | |
206 | 'jit-lock-fontify-buffer)) | |
207 | ||
7840ced1 GM |
208 | ;; Install an idle timer for stealth fontification. |
209 | (when (and jit-lock-stealth-time | |
210 | (null jit-lock-stealth-timer)) | |
02b420eb | 211 | (setq jit-lock-stealth-timer |
7840ced1 GM |
212 | (run-with-idle-timer jit-lock-stealth-time |
213 | jit-lock-stealth-time | |
214 | 'jit-lock-stealth-fontify))) | |
215 | ||
bcacade9 | 216 | ;; Initialize deferred contextual fontification if requested. |
7840ced1 GM |
217 | (when (or (eq jit-lock-defer-contextually 'always) |
218 | (and (not (eq jit-lock-defer-contextually 'never)) | |
219 | (null font-lock-keywords-only))) | |
bcacade9 SM |
220 | (setq jit-lock-first-unfontify-pos (point-max))) |
221 | ||
222 | ;; Setup our after-change-function | |
223 | ;; and remove font-lock's (if any). | |
224 | (remove-hook 'after-change-functions 'font-lock-after-change-function t) | |
225 | (add-hook 'after-change-functions 'jit-lock-after-change nil t) | |
7840ced1 GM |
226 | |
227 | ;; Install the fontification hook. | |
228 | (add-hook 'fontification-functions 'jit-lock-function)) | |
229 | ||
230 | ;; Turn Just-in-time Lock mode off. | |
231 | (t | |
232 | ;; Cancel our idle timer. | |
233 | (when jit-lock-stealth-timer | |
234 | (cancel-timer jit-lock-stealth-timer) | |
235 | (setq jit-lock-stealth-timer nil)) | |
236 | ||
02b420eb SM |
237 | ;; Restore non-JIT font-lock-fontify-buffer. |
238 | (when jit-lock-saved-fontify-buffer-function | |
239 | (set (make-local-variable 'font-lock-fontify-buffer-function) | |
240 | jit-lock-saved-fontify-buffer-function) | |
241 | (setq jit-lock-saved-fontify-buffer-function nil)) | |
242 | ||
bcacade9 | 243 | ;; Remove hooks (and restore font-lock's if necessary). |
02b420eb | 244 | (remove-hook 'after-change-functions 'jit-lock-after-change t) |
bcacade9 SM |
245 | (when font-lock-mode |
246 | (add-hook 'after-change-functions | |
247 | 'font-lock-after-change-function nil t)) | |
7840ced1 GM |
248 | (remove-hook 'fontification-functions 'jit-lock-function)))) |
249 | ||
250 | ||
02b420eb SM |
251 | ;; This function is used to prevent font-lock-fontify-buffer from |
252 | ;; fontifying eagerly the whole buffer. This is important for | |
253 | ;; things like CWarn mode which adds/removes a few keywords and | |
254 | ;; does a refontify (which takes ages on large files). | |
255 | (defun jit-lock-fontify-buffer () | |
bcacade9 | 256 | (with-buffer-prepared-for-jit-lock |
5a5987eb SM |
257 | (save-restriction |
258 | (widen) | |
259 | (add-text-properties (point-min) (point-max) '(fontified nil))))) | |
7840ced1 GM |
260 | |
261 | \f | |
262 | ;;; On demand fontification. | |
263 | ||
264 | (defun jit-lock-function (start) | |
265 | "Fontify current buffer starting at position START. | |
266 | This function is added to `fontification-functions' when `jit-lock-mode' | |
267 | is active." | |
268 | (when jit-lock-mode | |
9f1a8fb4 | 269 | (jit-lock-function-1 start))) |
60bffb78 GM |
270 | |
271 | ||
272 | (defun jit-lock-function-1 (start) | |
02b420eb | 273 | "Fontify current buffer starting at position START." |
bcacade9 | 274 | (with-buffer-prepared-for-jit-lock |
60bffb78 GM |
275 | (save-excursion |
276 | (save-restriction | |
277 | (widen) | |
278 | (let ((end (min (point-max) (+ start jit-lock-chunk-size))) | |
279 | (parse-sexp-lookup-properties font-lock-syntactic-keywords) | |
280 | (font-lock-beginning-of-syntax-function nil) | |
281 | (old-syntax-table (syntax-table)) | |
282 | next font-lock-start font-lock-end) | |
283 | (when font-lock-syntax-table | |
284 | (set-syntax-table font-lock-syntax-table)) | |
285 | (save-match-data | |
286 | (condition-case error | |
287 | ;; Fontify chunks beginning at START. The end of a | |
288 | ;; chunk is either `end', or the start of a region | |
289 | ;; before `end' that has already been fontified. | |
290 | (while start | |
291 | ;; Determine the end of this chunk. | |
292 | (setq next (or (text-property-any start end 'fontified t) | |
293 | end)) | |
294 | ||
295 | ;; Decide which range of text should be fontified. | |
296 | ;; The problem is that START and NEXT may be in the | |
297 | ;; middle of something matched by a font-lock regexp. | |
298 | ;; Until someone has a better idea, let's start | |
299 | ;; at the start of the line containing START and | |
300 | ;; stop at the start of the line following NEXT. | |
301 | (goto-char next) | |
302 | (setq font-lock-end (line-beginning-position 2)) | |
303 | (goto-char start) | |
304 | (setq font-lock-start (line-beginning-position)) | |
7840ced1 | 305 | |
60bffb78 GM |
306 | ;; Fontify the chunk, and mark it as fontified. |
307 | (font-lock-fontify-region font-lock-start font-lock-end nil) | |
308 | (add-text-properties start next '(fontified t)) | |
7840ced1 | 309 | |
60bffb78 GM |
310 | ;; Find the start of the next chunk, if any. |
311 | (setq start (text-property-any next end 'fontified nil))) | |
7840ced1 | 312 | |
60bffb78 GM |
313 | ((error quit) |
314 | (message "Fontifying region...%s" error)))) | |
7840ced1 | 315 | |
60bffb78 GM |
316 | ;; Restore previous buffer settings. |
317 | (set-syntax-table old-syntax-table)))))) | |
7840ced1 | 318 | |
7840ced1 GM |
319 | \f |
320 | ;;; Stealth fontification. | |
321 | ||
322 | (defsubst jit-lock-stealth-chunk-start (around) | |
323 | "Return the start of the next chunk to fontify around position AROUND.. | |
324 | Value is nil if there is nothing more to fontify." | |
8c887c51 GM |
325 | (if (zerop (buffer-size)) |
326 | nil | |
327 | (save-restriction | |
328 | (widen) | |
329 | (let* ((next (text-property-any around (point-max) 'fontified nil)) | |
330 | (prev (previous-single-property-change around 'fontified)) | |
331 | (prop (get-text-property (max (point-min) (1- around)) | |
332 | 'fontified)) | |
333 | (start (cond | |
334 | ((null prev) | |
335 | ;; There is no property change between AROUND | |
336 | ;; and the start of the buffer. If PROP is | |
337 | ;; non-nil, everything in front of AROUND is | |
338 | ;; fontified, otherwise nothing is fontified. | |
339 | (if prop | |
340 | nil | |
341 | (max (point-min) | |
342 | (- around (/ jit-lock-chunk-size 2))))) | |
343 | (prop | |
344 | ;; PREV is the start of a region of fontified | |
bcacade9 | 345 | ;; text containing AROUND. Start fontifying a |
8c887c51 GM |
346 | ;; chunk size before the end of the unfontified |
347 | ;; region in front of that. | |
348 | (max (or (previous-single-property-change prev 'fontified) | |
349 | (point-min)) | |
350 | (- prev jit-lock-chunk-size))) | |
351 | (t | |
352 | ;; PREV is the start of a region of unfontified | |
353 | ;; text containing AROUND. Start at PREV or | |
354 | ;; chunk size in front of AROUND, whichever is | |
355 | ;; nearer. | |
356 | (max prev (- around jit-lock-chunk-size))))) | |
357 | (result (cond ((null start) next) | |
358 | ((null next) start) | |
359 | ((< (- around start) (- next around)) start) | |
360 | (t next)))) | |
361 | result)))) | |
362 | ||
7840ced1 GM |
363 | |
364 | (defun jit-lock-stealth-fontify () | |
365 | "Fontify buffers stealthily. | |
366 | This functions is called after Emacs has been idle for | |
367 | `jit-lock-stealth-time' seconds." | |
368 | (unless (or executing-kbd-macro | |
369 | (window-minibuffer-p (selected-window))) | |
370 | (let ((buffers (buffer-list)) | |
371 | minibuffer-auto-raise | |
372 | message-log-max) | |
8c887c51 | 373 | (while (and buffers (not (input-pending-p))) |
7840ced1 GM |
374 | (let ((buffer (car buffers))) |
375 | (setq buffers (cdr buffers)) | |
8c887c51 | 376 | |
7840ced1 GM |
377 | (with-current-buffer buffer |
378 | (when jit-lock-mode | |
379 | ;; This is funny. Calling sit-for with 3rd arg non-nil | |
380 | ;; so that it doesn't redisplay, internally calls | |
381 | ;; wait_reading_process_input also with a parameter | |
382 | ;; saying "don't redisplay." Since this function here | |
383 | ;; is called periodically, this effectively leads to | |
384 | ;; process output not being redisplayed at all because | |
385 | ;; redisplay_internal is never called. (That didn't | |
386 | ;; work in the old redisplay either.) So, we learn that | |
387 | ;; we mustn't call sit-for that way here. But then, we | |
388 | ;; have to be cautious not to call sit-for in a widened | |
389 | ;; buffer, since this could display hidden parts of that | |
390 | ;; buffer. This explains the seemingly weird use of | |
391 | ;; save-restriction/widen here. | |
392 | ||
393 | (with-temp-message (if jit-lock-stealth-verbose | |
394 | (concat "JIT stealth lock " | |
395 | (buffer-name))) | |
8c887c51 | 396 | |
9f1a8fb4 GM |
397 | ;; Perform deferred unfontification, if any. |
398 | (when jit-lock-first-unfontify-pos | |
399 | (save-restriction | |
400 | (widen) | |
401 | (when (and (>= jit-lock-first-unfontify-pos (point-min)) | |
402 | (< jit-lock-first-unfontify-pos (point-max))) | |
bcacade9 | 403 | (with-buffer-prepared-for-jit-lock |
9f1a8fb4 GM |
404 | (put-text-property jit-lock-first-unfontify-pos |
405 | (point-max) 'fontified nil)) | |
bcacade9 | 406 | (setq jit-lock-first-unfontify-pos (point-max))))) |
9f1a8fb4 GM |
407 | |
408 | ;; In the following code, the `sit-for' calls cause a | |
409 | ;; redisplay, so it's required that the | |
410 | ;; buffer-modified flag of a buffer that is displayed | |
411 | ;; has the right value---otherwise the mode line of | |
412 | ;; an unmodified buffer would show a `*'. | |
413 | (let (start | |
414 | (nice (or jit-lock-stealth-nice 0)) | |
415 | (point (point))) | |
416 | (while (and (setq start | |
417 | (jit-lock-stealth-chunk-start point)) | |
418 | (sit-for nice)) | |
7840ced1 | 419 | |
9f1a8fb4 GM |
420 | ;; Wait a little if load is too high. |
421 | (when (and jit-lock-stealth-load | |
422 | (> (car (load-average)) jit-lock-stealth-load)) | |
423 | (sit-for (or jit-lock-stealth-time 30))) | |
7840ced1 | 424 | |
9f1a8fb4 GM |
425 | ;; Unless there's input pending now, fontify. |
426 | (unless (input-pending-p) | |
427 | (jit-lock-function-1 start)))))))))))) | |
7840ced1 GM |
428 | |
429 | ||
430 | \f | |
431 | ;;; Deferred fontification. | |
432 | ||
433 | (defun jit-lock-after-change (start end old-len) | |
434 | "Mark the rest of the buffer as not fontified after a change. | |
435 | Installed on `after-change-functions'. | |
436 | START and END are the start and end of the changed text. OLD-LEN | |
437 | is the pre-change length. | |
438 | This function ensures that lines following the change will be refontified | |
439 | in case the syntax of those lines has changed. Refontification | |
440 | will take place when text is fontified stealthily." | |
7840ced1 | 441 | (when jit-lock-mode |
d9330f43 SM |
442 | (save-excursion |
443 | (with-buffer-prepared-for-jit-lock | |
444 | ;; It's important that the `fontified' property be set from the | |
445 | ;; beginning of the line, else font-lock will properly change the | |
446 | ;; text's face, but the display will have been done already and will | |
447 | ;; be inconsistent with the buffer's content. | |
448 | (goto-char start) | |
449 | (setq start (line-beginning-position)) | |
450 | ;; Make sure we change at least one char (in case of deletions). | |
451 | (setq end (min (max end (1+ start)) (point-max))) | |
452 | ;; Request refontification. | |
453 | (put-text-property start end 'fontified nil)) | |
454 | ;; Mark the change for deferred contextual refontification. | |
455 | (when jit-lock-first-unfontify-pos | |
456 | (setq jit-lock-first-unfontify-pos | |
457 | (min jit-lock-first-unfontify-pos start)))))) | |
7840ced1 | 458 | |
7840ced1 GM |
459 | (provide 'jit-lock) |
460 | ||
461 | ;; jit-lock.el ends here |