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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 | |
36 | (defmacro with-buffer-prepared-for-font-lock (&rest body) | |
37 | "Execute BODY in current buffer, overriding several variables. | |
38 | Preserves the `buffer-modified-p' state of the current buffer." | |
39 | `(let ((modified (buffer-modified-p)) | |
40 | (buffer-undo-list t) | |
41 | (inhibit-read-only t) | |
42 | (inhibit-point-motion-hooks t) | |
43 | before-change-functions | |
44 | after-change-functions | |
45 | deactivate-mark | |
46 | buffer-file-name | |
47 | buffer-file-truename) | |
48 | ,@body | |
49 | (set-buffer-modified-p modified)))) | |
50 | ||
51 | ||
52 | \f | |
53 | ;;; Customization. | |
54 | ||
55 | (defcustom jit-lock-chunk-size 500 | |
56 | "*Font-lock chunks of this many characters, or smaller." | |
57 | :type 'integer | |
58 | :group 'jit-lock) | |
59 | ||
60 | ||
61 | (defcustom jit-lock-stealth-time 3 | |
62 | "*Time in seconds to wait before beginning stealth fontification. | |
63 | Stealth fontification occurs if there is no input within this time. | |
64 | If nil, means stealth fontification is never performed. | |
65 | ||
66 | The value of this variable is used when JIT Lock mode is turned on." | |
67 | :type '(choice (const :tag "never" nil) | |
68 | (number :tag "seconds")) | |
69 | :group 'jit-lock) | |
70 | ||
71 | ||
72 | (defcustom jit-lock-stealth-nice 0.125 | |
73 | "*Time in seconds to pause between chunks of stealth fontification. | |
74 | Each iteration of stealth fontification is separated by this amount of time, | |
75 | thus reducing the demand that stealth fontification makes on the system. | |
76 | If nil, means stealth fontification is never paused. | |
77 | To reduce machine load during stealth fontification, at the cost of stealth | |
78 | taking longer to fontify, you could increase the value of this variable. | |
79 | See also `jit-lock-stealth-load'." | |
80 | :type '(choice (const :tag "never" nil) | |
81 | (number :tag "seconds")) | |
82 | :group 'jit-lock) | |
83 | ||
84 | ||
85 | (defcustom jit-lock-stealth-load | |
86 | (if (condition-case nil (load-average) (error)) 200) | |
87 | "*Load in percentage above which stealth fontification is suspended. | |
88 | Stealth fontification pauses when the system short-term load average (as | |
89 | returned by the function `load-average' if supported) goes above this level, | |
90 | thus reducing the demand that stealth fontification makes on the system. | |
91 | If nil, means stealth fontification is never suspended. | |
92 | To reduce machine load during stealth fontification, at the cost of stealth | |
93 | taking longer to fontify, you could reduce the value of this variable. | |
94 | See also `jit-lock-stealth-nice'." | |
95 | :type (if (condition-case nil (load-average) (error)) | |
96 | '(choice (const :tag "never" nil) | |
97 | (integer :tag "load")) | |
98 | '(const :format "%t: unsupported\n" nil)) | |
99 | :group 'jit-lock) | |
100 | ||
101 | ||
102 | (defcustom jit-lock-stealth-verbose nil | |
103 | "*If non-nil, means stealth fontification should show status messages." | |
104 | :type 'boolean | |
105 | :group 'jit-lock) | |
106 | ||
107 | ||
108 | (defcustom jit-lock-defer-contextually 'syntax-driven | |
109 | "*If non-nil, means deferred fontification should be syntactically true. | |
110 | If nil, means deferred fontification occurs only on those lines modified. This | |
111 | means where modification on a line causes syntactic change on subsequent lines, | |
112 | those subsequent lines are not refontified to reflect their new context. | |
113 | If t, means deferred fontification occurs on those lines modified and all | |
114 | subsequent lines. This means those subsequent lines are refontified to reflect | |
115 | their new syntactic context, either immediately or when scrolling into them. | |
116 | If any other value, e.g., `syntax-driven', means deferred syntactically true | |
117 | fontification occurs only if syntactic fontification is performed using the | |
118 | buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil. | |
119 | ||
120 | The value of this variable is used when JIT Lock mode is turned on." | |
121 | :type '(choice (const :tag "never" nil) | |
122 | (const :tag "always" t) | |
123 | (other :tag "syntax-driven" syntax-driven)) | |
124 | :group 'jit-lock) | |
125 | ||
126 | ||
127 | \f | |
128 | ;;; Variables that are not customizable. | |
129 | ||
130 | (defvar jit-lock-mode nil | |
131 | "Non-nil means Just-in-time Lock mode is active.") | |
132 | (make-variable-buffer-local 'jit-lock-mode) | |
133 | ||
134 | ||
135 | (defvar jit-lock-first-unfontify-pos nil | |
136 | "Consider text after this position as unfontified.") | |
137 | (make-variable-buffer-local 'jit-lock-first-unfontify-pos) | |
138 | ||
139 | ||
140 | (defvar jit-lock-stealth-timer nil | |
141 | "Timer for stealth fontification in Just-in-time Lock mode.") | |
142 | ||
143 | ||
144 | \f | |
145 | ;;; JIT lock mode | |
146 | ||
147 | ;;;###autoload | |
148 | (defun jit-lock-mode (arg) | |
149 | "Toggle Just-in-time Lock mode. | |
150 | With arg, turn Just-in-time Lock mode on if and only if arg is positive. | |
151 | Enable it automatically by customizing group `font-lock'. | |
152 | ||
153 | When Just-in-time Lock mode is enabled, fontification is different in the | |
154 | following ways: | |
155 | ||
156 | - Demand-driven buffer fontification triggered by Emacs C code. | |
157 | This means initial fontification of the whole buffer does not occur. | |
158 | Instead, fontification occurs when necessary, such as when scrolling | |
159 | through the buffer would otherwise reveal unfontified areas. This is | |
160 | useful if buffer fontification is too slow for large buffers. | |
161 | ||
162 | - Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil. | |
163 | This means remaining unfontified areas of buffers are fontified if Emacs has | |
164 | been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle. | |
165 | This is useful if any buffer has any deferred fontification. | |
166 | ||
167 | - Deferred context fontification if `jit-lock-defer-contextually' is | |
168 | non-nil. This means fontification updates the buffer corresponding to | |
169 | true syntactic context, after `jit-lock-stealth-time' seconds of Emacs | |
170 | idle time, while Emacs remains idle. Otherwise, fontification occurs | |
171 | on modified lines only, and subsequent lines can remain fontified | |
172 | corresponding to previous syntactic contexts. This is useful where | |
173 | strings or comments span lines. | |
174 | ||
175 | Stealth fontification only occurs while the system remains unloaded. | |
176 | If the system load rises above `jit-lock-stealth-load' percent, stealth | |
177 | fontification is suspended. Stealth fontification intensity is controlled via | |
178 | the variable `jit-lock-stealth-nice' and `jit-lock-stealth-lines'." | |
179 | (interactive "P") | |
180 | (setq jit-lock-mode (if arg | |
181 | (> (prefix-numeric-value arg) 0) | |
182 | (not jit-lock-mode))) | |
183 | (cond ((and jit-lock-mode | |
184 | (or (not (boundp 'font-lock-mode)) | |
185 | (not font-lock-mode))) | |
186 | ;; If font-lock is not on, turn it on, with Just-in-time | |
187 | ;; Lock mode as support mode; font-lock will call us again. | |
188 | (let ((font-lock-support-mode 'jit-lock-mode)) | |
189 | (font-lock-mode t))) | |
190 | ||
191 | ;; Turn Just-in-time Lock mode on. | |
192 | (jit-lock-mode | |
193 | ;; Setting `font-lock-fontified' makes font-lock believe the | |
194 | ;; buffer is already fontified, so that it won't highlight | |
195 | ;; the whole buffer. | |
196 | (make-local-variable 'font-lock-fontified) | |
197 | (setq font-lock-fontified t) | |
198 | ||
199 | (setq jit-lock-first-unfontify-pos nil) | |
200 | ||
201 | ;; Install an idle timer for stealth fontification. | |
202 | (when (and jit-lock-stealth-time | |
203 | (null jit-lock-stealth-timer)) | |
204 | (setq jit-lock-stealth-timer | |
205 | (run-with-idle-timer jit-lock-stealth-time | |
206 | jit-lock-stealth-time | |
207 | 'jit-lock-stealth-fontify))) | |
208 | ||
209 | ;; Add a hook for deferred contectual fontification. | |
210 | (when (or (eq jit-lock-defer-contextually 'always) | |
211 | (and (not (eq jit-lock-defer-contextually 'never)) | |
212 | (null font-lock-keywords-only))) | |
213 | (add-hook 'after-change-functions 'jit-lock-after-change)) | |
214 | ||
215 | ;; Install the fontification hook. | |
216 | (add-hook 'fontification-functions 'jit-lock-function)) | |
217 | ||
218 | ;; Turn Just-in-time Lock mode off. | |
219 | (t | |
220 | ;; Cancel our idle timer. | |
221 | (when jit-lock-stealth-timer | |
222 | (cancel-timer jit-lock-stealth-timer) | |
223 | (setq jit-lock-stealth-timer nil)) | |
224 | ||
225 | ;; Remove hooks. | |
226 | (remove-hook 'after-change-functions 'jit-lock-after-change) | |
227 | (remove-hook 'fontification-functions 'jit-lock-function)))) | |
228 | ||
229 | ||
230 | ;;;###autoload | |
231 | (defun turn-on-jit-lock () | |
232 | "Unconditionally turn on Just-in-time Lock mode." | |
233 | (jit-lock-mode 1)) | |
234 | ||
235 | ||
236 | \f | |
237 | ;;; On demand fontification. | |
238 | ||
239 | (defun jit-lock-function (start) | |
240 | "Fontify current buffer starting at position START. | |
241 | This function is added to `fontification-functions' when `jit-lock-mode' | |
242 | is active." | |
243 | (when jit-lock-mode | |
244 | (with-buffer-prepared-for-font-lock | |
245 | (let ((end (min (point-max) (+ start jit-lock-chunk-size))) | |
246 | (parse-sexp-lookup-properties font-lock-syntactic-keywords) | |
247 | (old-syntax-table (syntax-table)) | |
248 | (font-lock-beginning-of-syntax-function nil) | |
b3424306 | 249 | next font-lock-start font-lock-end) |
7840ced1 GM |
250 | (when font-lock-syntax-table |
251 | (set-syntax-table font-lock-syntax-table)) | |
252 | (save-excursion | |
253 | (save-restriction | |
254 | (widen) | |
255 | (save-match-data | |
256 | (condition-case error | |
257 | ;; Fontify chunks beginning at START. The end of a | |
258 | ;; chunk is either `end', or the start of a region | |
259 | ;; before `end' that has already been fontified. | |
260 | (while start | |
261 | ;; Determine the end of this chunk. | |
262 | (setq next (or (text-property-any start end 'fontified t) | |
263 | end)) | |
b3424306 GM |
264 | |
265 | ;; Decide which range of text should be fontified. | |
266 | ;; The problem is that START and NEXT may be in the | |
267 | ;; middle of something matched by a font-lock regexp. | |
268 | ;; Until someone has a better idea, let's start | |
269 | ;; at the start of the line containing START and | |
270 | ;; stop at the start of the line following NEXT. | |
271 | (goto-char next) | |
272 | (setq font-lock-end (line-beginning-position 2)) | |
7840ced1 | 273 | (goto-char start) |
b3424306 | 274 | (setq font-lock-start (line-beginning-position)) |
7840ced1 GM |
275 | |
276 | ;; Fontify the chunk, and mark it as fontified. | |
b3424306 | 277 | (font-lock-fontify-region font-lock-start font-lock-end nil) |
7840ced1 GM |
278 | (add-text-properties start next '(fontified t)) |
279 | ||
280 | ;; Find the start of the next chunk, if any. | |
281 | (setq start (text-property-any next end 'fontified nil))) | |
282 | ||
283 | ((error quit) | |
284 | (message "Fontifying region...%s" error)))))) | |
285 | ||
286 | ;; Restore previous buffer settings. | |
287 | (set-syntax-table old-syntax-table))))) | |
288 | ||
289 | ||
290 | (defun jit-lock-after-fontify-buffer () | |
291 | "Mark the current buffer as fontified. | |
292 | Called from `font-lock-after-fontify-buffer." | |
293 | (with-buffer-prepared-for-font-lock | |
294 | (add-text-properties (point-min) (point-max) '(fontified t)))) | |
295 | ||
296 | ||
297 | (defun jit-lock-after-unfontify-buffer () | |
298 | "Mark the current buffer as unfontified. | |
299 | Called from `font-lock-after-fontify-buffer." | |
300 | (with-buffer-prepared-for-font-lock | |
301 | (remove-text-properties (point-min) (point-max) '(fontified nil)))) | |
302 | ||
303 | ||
304 | \f | |
305 | ;;; Stealth fontification. | |
306 | ||
307 | (defsubst jit-lock-stealth-chunk-start (around) | |
308 | "Return the start of the next chunk to fontify around position AROUND.. | |
309 | Value is nil if there is nothing more to fontify." | |
310 | (save-restriction | |
311 | (widen) | |
312 | (let ((prev (previous-single-property-change around 'fontified)) | |
313 | (next (text-property-any around (point-max) 'fontified nil)) | |
314 | (prop (get-text-property around 'fontified))) | |
315 | (cond ((and (null prop) | |
316 | (< around (point-max))) | |
317 | ;; Text at position AROUND is not fontified. The value of | |
318 | ;; prev, if non-nil, is the start of the region of | |
319 | ;; unfontified text. As a special case, prop will always | |
320 | ;; be nil at point-max. So don't handle that case here. | |
321 | (max (or prev (point-min)) | |
322 | (- around jit-lock-chunk-size))) | |
323 | ||
324 | ((null prev) | |
325 | ;; Text at AROUND is fontified, and everything up to | |
326 | ;; point-min is. Return the value of next. If that is | |
327 | ;; nil, there is nothing left to fontify. | |
328 | next) | |
329 | ||
330 | ((or (null next) | |
331 | (< (- around prev) (- next around))) | |
332 | ;; We either have no unfontified text following AROUND, or | |
333 | ;; the unfontified text in front of AROUND is nearer. The | |
334 | ;; value of prev is the end of the region of unfontified | |
335 | ;; text in front of AROUND. | |
336 | (let ((start (previous-single-property-change prev 'fontified))) | |
337 | (max (or start (point-min)) | |
338 | (- prev jit-lock-chunk-size)))) | |
339 | ||
340 | (t | |
341 | next))))) | |
342 | ||
343 | ||
344 | (defun jit-lock-stealth-fontify () | |
345 | "Fontify buffers stealthily. | |
346 | This functions is called after Emacs has been idle for | |
347 | `jit-lock-stealth-time' seconds." | |
348 | (unless (or executing-kbd-macro | |
349 | (window-minibuffer-p (selected-window))) | |
350 | (let ((buffers (buffer-list)) | |
351 | minibuffer-auto-raise | |
352 | message-log-max) | |
353 | (while (and buffers | |
354 | (not (input-pending-p))) | |
355 | (let ((buffer (car buffers))) | |
356 | (setq buffers (cdr buffers)) | |
357 | (with-current-buffer buffer | |
358 | (when jit-lock-mode | |
359 | ;; This is funny. Calling sit-for with 3rd arg non-nil | |
360 | ;; so that it doesn't redisplay, internally calls | |
361 | ;; wait_reading_process_input also with a parameter | |
362 | ;; saying "don't redisplay." Since this function here | |
363 | ;; is called periodically, this effectively leads to | |
364 | ;; process output not being redisplayed at all because | |
365 | ;; redisplay_internal is never called. (That didn't | |
366 | ;; work in the old redisplay either.) So, we learn that | |
367 | ;; we mustn't call sit-for that way here. But then, we | |
368 | ;; have to be cautious not to call sit-for in a widened | |
369 | ;; buffer, since this could display hidden parts of that | |
370 | ;; buffer. This explains the seemingly weird use of | |
371 | ;; save-restriction/widen here. | |
372 | ||
373 | (with-temp-message (if jit-lock-stealth-verbose | |
374 | (concat "JIT stealth lock " | |
375 | (buffer-name))) | |
376 | ||
377 | ;; Perform deferred unfontification, if any. | |
378 | (when jit-lock-first-unfontify-pos | |
379 | (save-restriction | |
380 | (widen) | |
381 | (when (and (>= jit-lock-first-unfontify-pos (point-min)) | |
382 | (< jit-lock-first-unfontify-pos (point-max))) | |
383 | (with-buffer-prepared-for-font-lock | |
384 | (put-text-property jit-lock-first-unfontify-pos | |
385 | (point-max) 'fontified nil)) | |
386 | (setq jit-lock-first-unfontify-pos nil)))) | |
387 | ||
388 | (let (start | |
389 | (nice (or jit-lock-stealth-nice 0)) | |
390 | (point (point))) | |
391 | (while (and (setq start | |
392 | (jit-lock-stealth-chunk-start point)) | |
393 | (sit-for nice)) | |
394 | ||
395 | ;; Wait a little if load is too high. | |
396 | (when (and jit-lock-stealth-load | |
397 | (> (car (load-average)) jit-lock-stealth-load)) | |
398 | (sit-for (or jit-lock-stealth-time 30))) | |
399 | ||
400 | ;; Unless there's input pending now, fontify. | |
401 | (unless (input-pending-p) | |
402 | (jit-lock-function start)))))))))))) | |
403 | ||
404 | ||
405 | \f | |
406 | ;;; Deferred fontification. | |
407 | ||
408 | (defun jit-lock-after-change (start end old-len) | |
409 | "Mark the rest of the buffer as not fontified after a change. | |
410 | Installed on `after-change-functions'. | |
411 | START and END are the start and end of the changed text. OLD-LEN | |
412 | is the pre-change length. | |
413 | This function ensures that lines following the change will be refontified | |
414 | in case the syntax of those lines has changed. Refontification | |
415 | will take place when text is fontified stealthily." | |
416 | ;; Don't do much here---removing text properties is too slow for | |
417 | ;; fast typers, giving them the impression of Emacs not being | |
418 | ;; very responsive. | |
419 | (when jit-lock-mode | |
420 | (setq jit-lock-first-unfontify-pos | |
421 | (if jit-lock-first-unfontify-pos | |
422 | (min jit-lock-first-unfontify-pos start) | |
423 | start)))) | |
424 | ||
425 | ||
426 | (provide 'jit-lock) | |
427 | ||
428 | ;; jit-lock.el ends here |