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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 | |
7ff02969 GM |
49 | ;; Calling set-buffer-modified causes redisplay to consider |
50 | ;; all windows because that function sets update_mode_lines. | |
7840ced1 GM |
51 | (set-buffer-modified-p modified)))) |
52 | ||
53 | ||
54 | \f | |
55 | ;;; Customization. | |
56 | ||
57 | (defcustom jit-lock-chunk-size 500 | |
58 | "*Font-lock chunks of this many characters, or smaller." | |
59 | :type 'integer | |
60 | :group 'jit-lock) | |
61 | ||
62 | ||
63 | (defcustom jit-lock-stealth-time 3 | |
64 | "*Time in seconds to wait before beginning stealth fontification. | |
65 | Stealth fontification occurs if there is no input within this time. | |
66 | If nil, means stealth fontification is never performed. | |
67 | ||
68 | The value of this variable is used when JIT Lock mode is turned on." | |
69 | :type '(choice (const :tag "never" nil) | |
70 | (number :tag "seconds")) | |
71 | :group 'jit-lock) | |
72 | ||
73 | ||
74 | (defcustom jit-lock-stealth-nice 0.125 | |
75 | "*Time in seconds to pause between chunks of stealth fontification. | |
76 | Each iteration of stealth fontification is separated by this amount of time, | |
77 | thus reducing the demand that stealth fontification makes on the system. | |
78 | If nil, means stealth fontification is never paused. | |
79 | To reduce machine load during stealth fontification, at the cost of stealth | |
80 | taking longer to fontify, you could increase the value of this variable. | |
81 | See also `jit-lock-stealth-load'." | |
82 | :type '(choice (const :tag "never" nil) | |
83 | (number :tag "seconds")) | |
84 | :group 'jit-lock) | |
85 | ||
86 | ||
87 | (defcustom jit-lock-stealth-load | |
88 | (if (condition-case nil (load-average) (error)) 200) | |
89 | "*Load in percentage above which stealth fontification is suspended. | |
90 | Stealth fontification pauses when the system short-term load average (as | |
91 | returned by the function `load-average' if supported) goes above this level, | |
92 | thus reducing the demand that stealth fontification makes on the system. | |
93 | If nil, means stealth fontification is never suspended. | |
94 | To reduce machine load during stealth fontification, at the cost of stealth | |
95 | taking longer to fontify, you could reduce the value of this variable. | |
96 | See also `jit-lock-stealth-nice'." | |
97 | :type (if (condition-case nil (load-average) (error)) | |
98 | '(choice (const :tag "never" nil) | |
99 | (integer :tag "load")) | |
100 | '(const :format "%t: unsupported\n" nil)) | |
101 | :group 'jit-lock) | |
102 | ||
103 | ||
104 | (defcustom jit-lock-stealth-verbose nil | |
105 | "*If non-nil, means stealth fontification should show status messages." | |
106 | :type 'boolean | |
107 | :group 'jit-lock) | |
108 | ||
109 | ||
110 | (defcustom jit-lock-defer-contextually 'syntax-driven | |
111 | "*If non-nil, means deferred fontification should be syntactically true. | |
112 | If nil, means deferred fontification occurs only on those lines modified. This | |
113 | means where modification on a line causes syntactic change on subsequent lines, | |
114 | those subsequent lines are not refontified to reflect their new context. | |
115 | If t, means deferred fontification occurs on those lines modified and all | |
116 | subsequent lines. This means those subsequent lines are refontified to reflect | |
117 | their new syntactic context, either immediately or when scrolling into them. | |
118 | If any other value, e.g., `syntax-driven', means deferred syntactically true | |
119 | fontification occurs only if syntactic fontification is performed using the | |
120 | buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil. | |
121 | ||
122 | The value of this variable is used when JIT Lock mode is turned on." | |
123 | :type '(choice (const :tag "never" nil) | |
124 | (const :tag "always" t) | |
125 | (other :tag "syntax-driven" syntax-driven)) | |
126 | :group 'jit-lock) | |
127 | ||
128 | ||
129 | \f | |
130 | ;;; Variables that are not customizable. | |
131 | ||
132 | (defvar jit-lock-mode nil | |
133 | "Non-nil means Just-in-time Lock mode is active.") | |
134 | (make-variable-buffer-local 'jit-lock-mode) | |
135 | ||
136 | ||
137 | (defvar jit-lock-first-unfontify-pos nil | |
138 | "Consider text after this position as unfontified.") | |
139 | (make-variable-buffer-local 'jit-lock-first-unfontify-pos) | |
140 | ||
141 | ||
142 | (defvar jit-lock-stealth-timer nil | |
143 | "Timer for stealth fontification in Just-in-time Lock mode.") | |
144 | ||
145 | ||
146 | \f | |
147 | ;;; JIT lock mode | |
148 | ||
149 | ;;;###autoload | |
150 | (defun jit-lock-mode (arg) | |
151 | "Toggle Just-in-time Lock mode. | |
152 | With arg, turn Just-in-time Lock mode on if and only if arg is positive. | |
153 | Enable it automatically by customizing group `font-lock'. | |
154 | ||
155 | When Just-in-time Lock mode is enabled, fontification is different in the | |
156 | following ways: | |
157 | ||
158 | - Demand-driven buffer fontification triggered by Emacs C code. | |
159 | This means initial fontification of the whole buffer does not occur. | |
160 | Instead, fontification occurs when necessary, such as when scrolling | |
161 | through the buffer would otherwise reveal unfontified areas. This is | |
162 | useful if buffer fontification is too slow for large buffers. | |
163 | ||
164 | - Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil. | |
165 | This means remaining unfontified areas of buffers are fontified if Emacs has | |
166 | been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle. | |
167 | This is useful if any buffer has any deferred fontification. | |
168 | ||
169 | - Deferred context fontification if `jit-lock-defer-contextually' is | |
170 | non-nil. This means fontification updates the buffer corresponding to | |
171 | true syntactic context, after `jit-lock-stealth-time' seconds of Emacs | |
172 | idle time, while Emacs remains idle. Otherwise, fontification occurs | |
173 | on modified lines only, and subsequent lines can remain fontified | |
174 | corresponding to previous syntactic contexts. This is useful where | |
175 | strings or comments span lines. | |
176 | ||
177 | Stealth fontification only occurs while the system remains unloaded. | |
178 | If the system load rises above `jit-lock-stealth-load' percent, stealth | |
179 | fontification is suspended. Stealth fontification intensity is controlled via | |
180 | the variable `jit-lock-stealth-nice' and `jit-lock-stealth-lines'." | |
181 | (interactive "P") | |
182 | (setq jit-lock-mode (if arg | |
183 | (> (prefix-numeric-value arg) 0) | |
184 | (not jit-lock-mode))) | |
185 | (cond ((and jit-lock-mode | |
186 | (or (not (boundp 'font-lock-mode)) | |
187 | (not font-lock-mode))) | |
188 | ;; If font-lock is not on, turn it on, with Just-in-time | |
189 | ;; Lock mode as support mode; font-lock will call us again. | |
190 | (let ((font-lock-support-mode 'jit-lock-mode)) | |
191 | (font-lock-mode t))) | |
192 | ||
193 | ;; Turn Just-in-time Lock mode on. | |
194 | (jit-lock-mode | |
195 | ;; Setting `font-lock-fontified' makes font-lock believe the | |
196 | ;; buffer is already fontified, so that it won't highlight | |
197 | ;; the whole buffer. | |
198 | (make-local-variable 'font-lock-fontified) | |
199 | (setq font-lock-fontified t) | |
200 | ||
201 | (setq jit-lock-first-unfontify-pos nil) | |
202 | ||
203 | ;; Install an idle timer for stealth fontification. | |
204 | (when (and jit-lock-stealth-time | |
205 | (null jit-lock-stealth-timer)) | |
206 | (setq jit-lock-stealth-timer | |
207 | (run-with-idle-timer jit-lock-stealth-time | |
208 | jit-lock-stealth-time | |
209 | 'jit-lock-stealth-fontify))) | |
210 | ||
211 | ;; Add a hook for deferred contectual fontification. | |
212 | (when (or (eq jit-lock-defer-contextually 'always) | |
213 | (and (not (eq jit-lock-defer-contextually 'never)) | |
214 | (null font-lock-keywords-only))) | |
215 | (add-hook 'after-change-functions 'jit-lock-after-change)) | |
216 | ||
217 | ;; Install the fontification hook. | |
218 | (add-hook 'fontification-functions 'jit-lock-function)) | |
219 | ||
220 | ;; Turn Just-in-time Lock mode off. | |
221 | (t | |
222 | ;; Cancel our idle timer. | |
223 | (when jit-lock-stealth-timer | |
224 | (cancel-timer jit-lock-stealth-timer) | |
225 | (setq jit-lock-stealth-timer nil)) | |
226 | ||
227 | ;; Remove hooks. | |
228 | (remove-hook 'after-change-functions 'jit-lock-after-change) | |
229 | (remove-hook 'fontification-functions 'jit-lock-function)))) | |
230 | ||
231 | ||
232 | ;;;###autoload | |
233 | (defun turn-on-jit-lock () | |
234 | "Unconditionally turn on Just-in-time Lock mode." | |
235 | (jit-lock-mode 1)) | |
236 | ||
237 | ||
238 | \f | |
239 | ;;; On demand fontification. | |
240 | ||
241 | (defun jit-lock-function (start) | |
242 | "Fontify current buffer starting at position START. | |
243 | This function is added to `fontification-functions' when `jit-lock-mode' | |
244 | is active." | |
245 | (when jit-lock-mode | |
246 | (with-buffer-prepared-for-font-lock | |
8c887c51 GM |
247 | (save-excursion |
248 | (save-restriction | |
249 | (widen) | |
250 | (let ((end (min (point-max) (+ start jit-lock-chunk-size))) | |
251 | (parse-sexp-lookup-properties font-lock-syntactic-keywords) | |
252 | (font-lock-beginning-of-syntax-function nil) | |
253 | (old-syntax-table (syntax-table)) | |
254 | next font-lock-start font-lock-end) | |
255 | (when font-lock-syntax-table | |
256 | (set-syntax-table font-lock-syntax-table)) | |
7840ced1 GM |
257 | (save-match-data |
258 | (condition-case error | |
259 | ;; Fontify chunks beginning at START. The end of a | |
260 | ;; chunk is either `end', or the start of a region | |
261 | ;; before `end' that has already been fontified. | |
262 | (while start | |
263 | ;; Determine the end of this chunk. | |
264 | (setq next (or (text-property-any start end 'fontified t) | |
265 | end)) | |
b3424306 GM |
266 | |
267 | ;; Decide which range of text should be fontified. | |
268 | ;; The problem is that START and NEXT may be in the | |
269 | ;; middle of something matched by a font-lock regexp. | |
270 | ;; Until someone has a better idea, let's start | |
271 | ;; at the start of the line containing START and | |
272 | ;; stop at the start of the line following NEXT. | |
273 | (goto-char next) | |
274 | (setq font-lock-end (line-beginning-position 2)) | |
7840ced1 | 275 | (goto-char start) |
b3424306 | 276 | (setq font-lock-start (line-beginning-position)) |
7840ced1 GM |
277 | |
278 | ;; Fontify the chunk, and mark it as fontified. | |
b3424306 | 279 | (font-lock-fontify-region font-lock-start font-lock-end nil) |
7840ced1 GM |
280 | (add-text-properties start next '(fontified t)) |
281 | ||
282 | ;; Find the start of the next chunk, if any. | |
283 | (setq start (text-property-any next end 'fontified nil))) | |
284 | ||
285 | ((error quit) | |
8c887c51 | 286 | (message "Fontifying region...%s" error)))) |
7840ced1 | 287 | |
8c887c51 GM |
288 | ;; Restore previous buffer settings. |
289 | (set-syntax-table old-syntax-table))))))) | |
7840ced1 GM |
290 | |
291 | ||
292 | (defun jit-lock-after-fontify-buffer () | |
293 | "Mark the current buffer as fontified. | |
294 | Called from `font-lock-after-fontify-buffer." | |
295 | (with-buffer-prepared-for-font-lock | |
296 | (add-text-properties (point-min) (point-max) '(fontified t)))) | |
297 | ||
298 | ||
299 | (defun jit-lock-after-unfontify-buffer () | |
300 | "Mark the current buffer as unfontified. | |
301 | Called from `font-lock-after-fontify-buffer." | |
302 | (with-buffer-prepared-for-font-lock | |
303 | (remove-text-properties (point-min) (point-max) '(fontified nil)))) | |
304 | ||
305 | ||
306 | \f | |
307 | ;;; Stealth fontification. | |
308 | ||
309 | (defsubst jit-lock-stealth-chunk-start (around) | |
310 | "Return the start of the next chunk to fontify around position AROUND.. | |
311 | Value is nil if there is nothing more to fontify." | |
8c887c51 GM |
312 | (if (zerop (buffer-size)) |
313 | nil | |
314 | (save-restriction | |
315 | (widen) | |
316 | (let* ((next (text-property-any around (point-max) 'fontified nil)) | |
317 | (prev (previous-single-property-change around 'fontified)) | |
318 | (prop (get-text-property (max (point-min) (1- around)) | |
319 | 'fontified)) | |
320 | (start (cond | |
321 | ((null prev) | |
322 | ;; There is no property change between AROUND | |
323 | ;; and the start of the buffer. If PROP is | |
324 | ;; non-nil, everything in front of AROUND is | |
325 | ;; fontified, otherwise nothing is fontified. | |
326 | (if prop | |
327 | nil | |
328 | (max (point-min) | |
329 | (- around (/ jit-lock-chunk-size 2))))) | |
330 | (prop | |
331 | ;; PREV is the start of a region of fontified | |
332 | ;; text containing AROUND. Start fontfifying a | |
333 | ;; chunk size before the end of the unfontified | |
334 | ;; region in front of that. | |
335 | (max (or (previous-single-property-change prev 'fontified) | |
336 | (point-min)) | |
337 | (- prev jit-lock-chunk-size))) | |
338 | (t | |
339 | ;; PREV is the start of a region of unfontified | |
340 | ;; text containing AROUND. Start at PREV or | |
341 | ;; chunk size in front of AROUND, whichever is | |
342 | ;; nearer. | |
343 | (max prev (- around jit-lock-chunk-size))))) | |
344 | (result (cond ((null start) next) | |
345 | ((null next) start) | |
346 | ((< (- around start) (- next around)) start) | |
347 | (t next)))) | |
348 | result)))) | |
349 | ||
7840ced1 GM |
350 | |
351 | (defun jit-lock-stealth-fontify () | |
352 | "Fontify buffers stealthily. | |
353 | This functions is called after Emacs has been idle for | |
354 | `jit-lock-stealth-time' seconds." | |
355 | (unless (or executing-kbd-macro | |
356 | (window-minibuffer-p (selected-window))) | |
357 | (let ((buffers (buffer-list)) | |
358 | minibuffer-auto-raise | |
359 | message-log-max) | |
8c887c51 | 360 | (while (and buffers (not (input-pending-p))) |
7840ced1 GM |
361 | (let ((buffer (car buffers))) |
362 | (setq buffers (cdr buffers)) | |
8c887c51 | 363 | |
7840ced1 GM |
364 | (with-current-buffer buffer |
365 | (when jit-lock-mode | |
366 | ;; This is funny. Calling sit-for with 3rd arg non-nil | |
367 | ;; so that it doesn't redisplay, internally calls | |
368 | ;; wait_reading_process_input also with a parameter | |
369 | ;; saying "don't redisplay." Since this function here | |
370 | ;; is called periodically, this effectively leads to | |
371 | ;; process output not being redisplayed at all because | |
372 | ;; redisplay_internal is never called. (That didn't | |
373 | ;; work in the old redisplay either.) So, we learn that | |
374 | ;; we mustn't call sit-for that way here. But then, we | |
375 | ;; have to be cautious not to call sit-for in a widened | |
376 | ;; buffer, since this could display hidden parts of that | |
377 | ;; buffer. This explains the seemingly weird use of | |
378 | ;; save-restriction/widen here. | |
379 | ||
380 | (with-temp-message (if jit-lock-stealth-verbose | |
381 | (concat "JIT stealth lock " | |
382 | (buffer-name))) | |
8c887c51 | 383 | |
7840ced1 GM |
384 | ;; Perform deferred unfontification, if any. |
385 | (when jit-lock-first-unfontify-pos | |
386 | (save-restriction | |
387 | (widen) | |
388 | (when (and (>= jit-lock-first-unfontify-pos (point-min)) | |
389 | (< jit-lock-first-unfontify-pos (point-max))) | |
390 | (with-buffer-prepared-for-font-lock | |
391 | (put-text-property jit-lock-first-unfontify-pos | |
392 | (point-max) 'fontified nil)) | |
393 | (setq jit-lock-first-unfontify-pos nil)))) | |
394 | ||
395 | (let (start | |
396 | (nice (or jit-lock-stealth-nice 0)) | |
397 | (point (point))) | |
8c887c51 | 398 | (while (and (setq start (jit-lock-stealth-chunk-start point)) |
7840ced1 GM |
399 | (sit-for nice)) |
400 | ||
401 | ;; Wait a little if load is too high. | |
402 | (when (and jit-lock-stealth-load | |
403 | (> (car (load-average)) jit-lock-stealth-load)) | |
404 | (sit-for (or jit-lock-stealth-time 30))) | |
405 | ||
406 | ;; Unless there's input pending now, fontify. | |
407 | (unless (input-pending-p) | |
408 | (jit-lock-function start)))))))))))) | |
409 | ||
410 | ||
411 | \f | |
412 | ;;; Deferred fontification. | |
413 | ||
414 | (defun jit-lock-after-change (start end old-len) | |
415 | "Mark the rest of the buffer as not fontified after a change. | |
416 | Installed on `after-change-functions'. | |
417 | START and END are the start and end of the changed text. OLD-LEN | |
418 | is the pre-change length. | |
419 | This function ensures that lines following the change will be refontified | |
420 | in case the syntax of those lines has changed. Refontification | |
421 | will take place when text is fontified stealthily." | |
422 | ;; Don't do much here---removing text properties is too slow for | |
423 | ;; fast typers, giving them the impression of Emacs not being | |
424 | ;; very responsive. | |
425 | (when jit-lock-mode | |
426 | (setq jit-lock-first-unfontify-pos | |
427 | (if jit-lock-first-unfontify-pos | |
428 | (min jit-lock-first-unfontify-pos start) | |
429 | start)))) | |
430 | ||
431 | ||
432 | (provide 'jit-lock) | |
433 | ||
434 | ;; jit-lock.el ends here |