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[bpt/emacs.git] / lisp / jit-lock.el
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e8af40ee 1;;; jit-lock.el --- just-in-time fontification
7840ced1 2
0d30b337 3;; Copyright (C) 1998, 2000, 2001, 2002, 2003, 2004,
aaef169d 4;; 2005, 2006 Free Software Foundation, Inc.
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5
6;; Author: Gerd Moellmann <gerd@gnu.org>
7;; Keywords: faces files
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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
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23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
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25
26;;; Commentary:
27
28;; Just-in-time fontification, triggered by C redisplay code.
29
30;;; Code:
31
32
7840ced1 33(eval-when-compile
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34 (require 'cl)
35
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36 (defmacro with-buffer-unmodified (&rest body)
37 "Eval BODY, preserving the current buffer's modified state."
7b4d9d3b 38 (declare (debug t))
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39 (let ((modified (make-symbol "modified")))
40 `(let ((,modified (buffer-modified-p)))
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41 (unwind-protect
42 (progn ,@body)
43 (unless ,modified
44 (restore-buffer-modified-p nil))))))
f1180544 45
bcacade9 46 (defmacro with-buffer-prepared-for-jit-lock (&rest body)
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47 "Execute BODY in current buffer, overriding several variables.
48Preserves the `buffer-modified-p' state of the current buffer."
7b4d9d3b 49 (declare (debug t))
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50 `(with-buffer-unmodified
51 (let ((buffer-undo-list t)
52 (inhibit-read-only t)
53 (inhibit-point-motion-hooks t)
bcacade9 54 (inhibit-modification-hooks t)
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55 deactivate-mark
56 buffer-file-name
57 buffer-file-truename)
58 ,@body))))
7840ced1 59
f1180544 60
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61\f
62;;; Customization.
63
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64(defgroup jit-lock nil
65 "Font Lock support mode to fontify just-in-time."
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66 :version "21.1"
67 :group 'font-lock)
68
7840ced1 69(defcustom jit-lock-chunk-size 500
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70 "*Jit-lock fontifies chunks of at most this many characters at a time.
71
72This variable controls both display-time and stealth fontification."
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73 :type 'integer
74 :group 'jit-lock)
75
76
4739237d 77(defcustom jit-lock-stealth-time 16
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78 "*Time in seconds to wait before beginning stealth fontification.
79Stealth fontification occurs if there is no input within this time.
f86292a9 80If nil, stealth fontification is never performed.
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81
82The value of this variable is used when JIT Lock mode is turned on."
83 :type '(choice (const :tag "never" nil)
84 (number :tag "seconds"))
85 :group 'jit-lock)
86
87
4739237d 88(defcustom jit-lock-stealth-nice 0.5
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89 "*Time in seconds to pause between chunks of stealth fontification.
90Each iteration of stealth fontification is separated by this amount of time,
91thus reducing the demand that stealth fontification makes on the system.
92If nil, means stealth fontification is never paused.
93To reduce machine load during stealth fontification, at the cost of stealth
94taking longer to fontify, you could increase the value of this variable.
95See also `jit-lock-stealth-load'."
96 :type '(choice (const :tag "never" nil)
f1180544 97 (number :tag "seconds"))
7840ced1 98 :group 'jit-lock)
f1180544 99
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100
101(defcustom jit-lock-stealth-load
102 (if (condition-case nil (load-average) (error)) 200)
103 "*Load in percentage above which stealth fontification is suspended.
104Stealth fontification pauses when the system short-term load average (as
105returned by the function `load-average' if supported) goes above this level,
106thus reducing the demand that stealth fontification makes on the system.
107If nil, means stealth fontification is never suspended.
108To reduce machine load during stealth fontification, at the cost of stealth
109taking longer to fontify, you could reduce the value of this variable.
110See also `jit-lock-stealth-nice'."
111 :type (if (condition-case nil (load-average) (error))
112 '(choice (const :tag "never" nil)
113 (integer :tag "load"))
114 '(const :format "%t: unsupported\n" nil))
115 :group 'jit-lock)
116
117
118(defcustom jit-lock-stealth-verbose nil
119 "*If non-nil, means stealth fontification should show status messages."
120 :type 'boolean
121 :group 'jit-lock)
122
123
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124(defvaralias 'jit-lock-defer-contextually 'jit-lock-contextually)
125(defcustom jit-lock-contextually 'syntax-driven
126 "*If non-nil, means fontification should be syntactically true.
127If nil, means fontification occurs only on those lines modified. This
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128means where modification on a line causes syntactic change on subsequent lines,
129those subsequent lines are not refontified to reflect their new context.
f415f2d7 130If t, means fontification occurs on those lines modified and all
7840ced1 131subsequent lines. This means those subsequent lines are refontified to reflect
7b4d9d3b 132their new syntactic context, after `jit-lock-context-time' seconds.
f415f2d7 133If any other value, e.g., `syntax-driven', means syntactically true
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134fontification occurs only if syntactic fontification is performed using the
135buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil.
136
137The value of this variable is used when JIT Lock mode is turned on."
138 :type '(choice (const :tag "never" nil)
139 (const :tag "always" t)
140 (other :tag "syntax-driven" syntax-driven))
141 :group 'jit-lock)
142
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143(defcustom jit-lock-context-time 0.5
144 "Idle time after which text is contextually refontified, if applicable."
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145 :type '(number :tag "seconds")
146 :group 'jit-lock)
147
8e069ce2 148(defcustom jit-lock-defer-time nil ;; 0.25
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149 "Idle time after which deferred fontification should take place.
150If nil, fontification is not deferred."
151 :group 'jit-lock
152 :type '(choice (const :tag "never" nil)
153 (number :tag "seconds")))
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154\f
155;;; Variables that are not customizable.
156
157(defvar jit-lock-mode nil
158 "Non-nil means Just-in-time Lock mode is active.")
159(make-variable-buffer-local 'jit-lock-mode)
160
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161(defvar jit-lock-functions nil
162 "Functions to do the actual fontification.
163They are called with two arguments: the START and END of the region to fontify.")
a62e3c6f 164(make-variable-buffer-local 'jit-lock-functions)
7840ced1 165
623a1226 166(defvar jit-lock-context-unfontify-pos nil
a62e3c6f 167 "Consider text after this position as contextually unfontified.
bcacade9 168If nil, contextual fontification is disabled.")
623a1226 169(make-variable-buffer-local 'jit-lock-context-unfontify-pos)
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170
171
172(defvar jit-lock-stealth-timer nil
173 "Timer for stealth fontification in Just-in-time Lock mode.")
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174(defvar jit-lock-stealth-repeat-timer nil
175 "Timer for repeated stealth fontification in Just-in-time Lock mode.")
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176(defvar jit-lock-context-timer nil
177 "Timer for context fontification in Just-in-time Lock mode.")
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178(defvar jit-lock-defer-timer nil
179 "Timer for deferred fontification in Just-in-time Lock mode.")
180
623a1226 181(defvar jit-lock-defer-buffers nil
b743187d 182 "List of buffers with pending deferred fontification.")
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183(defvar jit-lock-stealth-buffers nil
184 "List of buffers that are being fontified stealthily.")
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185\f
186;;; JIT lock mode
187
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188(defun jit-lock-mode (arg)
189 "Toggle Just-in-time Lock mode.
bcacade9 190Turn Just-in-time Lock mode on if and only if ARG is non-nil.
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191Enable it automatically by customizing group `font-lock'.
192
193When Just-in-time Lock mode is enabled, fontification is different in the
194following ways:
195
196- Demand-driven buffer fontification triggered by Emacs C code.
197 This means initial fontification of the whole buffer does not occur.
198 Instead, fontification occurs when necessary, such as when scrolling
199 through the buffer would otherwise reveal unfontified areas. This is
200 useful if buffer fontification is too slow for large buffers.
201
202- Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil.
203 This means remaining unfontified areas of buffers are fontified if Emacs has
204 been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle.
205 This is useful if any buffer has any deferred fontification.
206
f415f2d7 207- Deferred context fontification if `jit-lock-contextually' is
7840ced1 208 non-nil. This means fontification updates the buffer corresponding to
7b4d9d3b 209 true syntactic context, after `jit-lock-context-time' seconds of Emacs
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210 idle time, while Emacs remains idle. Otherwise, fontification occurs
211 on modified lines only, and subsequent lines can remain fontified
212 corresponding to previous syntactic contexts. This is useful where
213 strings or comments span lines.
214
215Stealth fontification only occurs while the system remains unloaded.
216If the system load rises above `jit-lock-stealth-load' percent, stealth
217fontification is suspended. Stealth fontification intensity is controlled via
02b420eb 218the variable `jit-lock-stealth-nice'."
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219 (setq jit-lock-mode arg)
220 (cond (;; Turn Just-in-time Lock mode on.
221 jit-lock-mode
222
b743187d 223 ;; Mark the buffer for refontification.
a62e3c6f 224 (jit-lock-refontify)
02b420eb 225
7840ced1 226 ;; Install an idle timer for stealth fontification.
c94d5f40 227 (when (and jit-lock-stealth-time (null jit-lock-stealth-timer))
02b420eb 228 (setq jit-lock-stealth-timer
b743187d 229 (run-with-idle-timer jit-lock-stealth-time t
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230 'jit-lock-stealth-fontify)))
231
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232 ;; Create, but do not activate, the idle timer for repeated
233 ;; stealth fontification.
234 (when (and jit-lock-stealth-time (null jit-lock-stealth-repeat-timer))
235 (setq jit-lock-stealth-repeat-timer (timer-create))
236 (timer-set-function jit-lock-stealth-repeat-timer
237 'jit-lock-stealth-fontify '(t)))
238
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239 ;; Init deferred fontification timer.
240 (when (and jit-lock-defer-time (null jit-lock-defer-timer))
241 (setq jit-lock-defer-timer
242 (run-with-idle-timer jit-lock-defer-time t
243 'jit-lock-deferred-fontify)))
244
623a1226 245 ;; Initialize contextual fontification if requested.
f415f2d7 246 (when (eq jit-lock-contextually t)
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247 (unless jit-lock-context-timer
248 (setq jit-lock-context-timer
249 (run-with-idle-timer jit-lock-context-time t
250 'jit-lock-context-fontify)))
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251 (setq jit-lock-context-unfontify-pos
252 (or jit-lock-context-unfontify-pos (point-max))))
bcacade9 253
a62e3c6f 254 ;; Setup our hooks.
bcacade9 255 (add-hook 'after-change-functions 'jit-lock-after-change nil t)
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256 (add-hook 'fontification-functions 'jit-lock-function))
257
258 ;; Turn Just-in-time Lock mode off.
259 (t
b743187d 260 ;; Cancel our idle timers.
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261 (when (and (or jit-lock-stealth-timer jit-lock-defer-timer
262 jit-lock-context-timer)
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263 ;; Only if there's no other buffer using them.
264 (not (catch 'found
265 (dolist (buf (buffer-list))
266 (with-current-buffer buf
267 (when jit-lock-mode (throw 'found t)))))))
268 (when jit-lock-stealth-timer
269 (cancel-timer jit-lock-stealth-timer)
270 (setq jit-lock-stealth-timer nil))
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271 (when jit-lock-context-timer
272 (cancel-timer jit-lock-context-timer)
273 (setq jit-lock-context-timer nil))
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274 (when jit-lock-defer-timer
275 (cancel-timer jit-lock-defer-timer)
276 (setq jit-lock-defer-timer nil)))
7840ced1 277
a62e3c6f 278 ;; Remove hooks.
02b420eb 279 (remove-hook 'after-change-functions 'jit-lock-after-change t)
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280 (remove-hook 'fontification-functions 'jit-lock-function))))
281
c94d5f40 282(defun jit-lock-register (fun &optional contextual)
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283 "Register FUN as a fontification function to be called in this buffer.
284FUN will be called with two arguments START and END indicating the region
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285that needs to be (re)fontified.
286If non-nil, CONTEXTUAL means that a contextual fontification would be useful."
f8bacc70 287 (add-hook 'jit-lock-functions fun nil t)
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288 (when (and contextual jit-lock-contextually)
289 (set (make-local-variable 'jit-lock-contextually) t))
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290 (jit-lock-mode t))
291
292(defun jit-lock-unregister (fun)
8a677d4f 293 "Unregister FUN as a fontification function.
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294Only applies to the current buffer."
295 (remove-hook 'jit-lock-functions fun t)
a62e3c6f 296 (unless jit-lock-functions (jit-lock-mode nil)))
7840ced1 297
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298;; This function is used to prevent font-lock-fontify-buffer from
299;; fontifying eagerly the whole buffer. This is important for
300;; things like CWarn mode which adds/removes a few keywords and
301;; does a refontify (which takes ages on large files).
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302(defun jit-lock-refontify (&optional beg end)
303 "Force refontification of the region BEG..END (default whole buffer)."
bcacade9 304 (with-buffer-prepared-for-jit-lock
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305 (save-restriction
306 (widen)
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307 (put-text-property (or beg (point-min)) (or end (point-max))
308 'fontified nil))))
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309\f
310;;; On demand fontification.
311
312(defun jit-lock-function (start)
313 "Fontify current buffer starting at position START.
314This function is added to `fontification-functions' when `jit-lock-mode'
315is active."
74614ac6 316 (when (and jit-lock-mode (not memory-full))
0902822d 317 (if (null jit-lock-defer-timer)
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318 ;; No deferral.
319 (jit-lock-fontify-now start (+ start jit-lock-chunk-size))
320 ;; Record the buffer for later fontification.
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321 (unless (memq (current-buffer) jit-lock-defer-buffers)
322 (push (current-buffer) jit-lock-defer-buffers))
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323 ;; Mark the area as defer-fontified so that the redisplay engine
324 ;; is happy and so that the idle timer can find the places to fontify.
325 (with-buffer-prepared-for-jit-lock
326 (put-text-property start
327 (next-single-property-change
328 start 'fontified nil
329 (min (point-max) (+ start jit-lock-chunk-size)))
330 'fontified 'defer)))))
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331
332(defun jit-lock-fontify-now (&optional start end)
333 "Fontify current buffer from START to END.
334Defaults to the whole buffer. END can be out of bounds."
bcacade9 335 (with-buffer-prepared-for-jit-lock
60bffb78 336 (save-excursion
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337 (unless start (setq start (point-min)))
338 (setq end (if end (min end (point-max)) (point-max)))
339 ;; This did bind `font-lock-beginning-of-syntax-function' to
340 ;; nil at some point, for an unknown reason. Don't do this; it
341 ;; can make highlighting slow due to expensive calls to
342 ;; `parse-partial-sexp' in function
343 ;; `font-lock-fontify-syntactically-region'. Example: paging
344 ;; from the end of a buffer to its start, can do repeated
345 ;; `parse-partial-sexp' starting from `point-min', which can
346 ;; take a long time in a large buffer.
663e1660 347 (let ((orig-start start) next)
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348 (save-match-data
349 ;; Fontify chunks beginning at START. The end of a
350 ;; chunk is either `end', or the start of a region
351 ;; before `end' that has already been fontified.
352 (while start
353 ;; Determine the end of this chunk.
354 (setq next (or (text-property-any start end 'fontified t)
355 end))
356
357 ;; Decide which range of text should be fontified.
358 ;; The problem is that START and NEXT may be in the
359 ;; middle of something matched by a font-lock regexp.
360 ;; Until someone has a better idea, let's start
361 ;; at the start of the line containing START and
362 ;; stop at the start of the line following NEXT.
363 (goto-char next) (setq next (line-beginning-position 2))
364 (goto-char start) (setq start (line-beginning-position))
f1180544 365
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366 ;; Make sure the contextual refontification doesn't re-refontify
367 ;; what's already been refontified.
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368 (when (and jit-lock-context-unfontify-pos
369 (< jit-lock-context-unfontify-pos next)
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370 (>= jit-lock-context-unfontify-pos start)
371 ;; Don't move boundary forward if we have to
372 ;; refontify previous text. Otherwise, we risk moving
373 ;; it past the end of the multiline property and thus
374 ;; forget about this multiline region altogether.
375 (not (get-text-property start 'jit-lock-defer-multiline)))
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376 (setq jit-lock-context-unfontify-pos next))
377
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378 ;; Fontify the chunk, and mark it as fontified.
379 ;; We mark it first, to make sure that we don't indefinitely
380 ;; re-execute this fontification if an error occurs.
381 (put-text-property start next 'fontified t)
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382 (condition-case err
383 (run-hook-with-args 'jit-lock-functions start next)
384 ;; If the user quits (which shouldn't happen in normal on-the-fly
385 ;; jit-locking), make sure the fontification will be performed
386 ;; before displaying the block again.
387 (quit (put-text-property start next 'fontified nil)
388 (funcall 'signal (car err) (cdr err))))
c9cf2e67 389
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390 ;; The redisplay engine has already rendered the buffer up-to
391 ;; `orig-start' and won't notice if the above jit-lock-functions
392 ;; changed the appearance of any part of the buffer prior
393 ;; to that. So if `start' is before `orig-start', we need to
394 ;; cause a new redisplay cycle after this one so that any changes
395 ;; are properly reflected on screen.
396 ;; To make such repeated redisplay happen less often, we can
397 ;; eagerly extend the refontified region with
398 ;; jit-lock-after-change-extend-region-functions.
399 (when (< start orig-start)
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400 (lexical-let ((start start)
401 (orig-start orig-start)
402 (buf (current-buffer)))
403 (run-with-timer
404 0 nil (lambda ()
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405 (with-current-buffer buf
406 (with-buffer-prepared-for-jit-lock
407 (put-text-property start orig-start
408 'fontified t)))))))
663e1660 409
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410 ;; Find the start of the next chunk, if any.
411 (setq start (text-property-any next end 'fontified nil))))))))
7840ced1 412
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413\f
414;;; Stealth fontification.
415
416(defsubst jit-lock-stealth-chunk-start (around)
417 "Return the start of the next chunk to fontify around position AROUND..
418Value is nil if there is nothing more to fontify."
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419 (if (zerop (buffer-size))
420 nil
421 (save-restriction
422 (widen)
b743187d 423 (let* ((next (text-property-not-all around (point-max) 'fontified t))
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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.
b743187d 433 (if (eq prop t)
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434 nil
435 (max (point-min)
436 (- around (/ jit-lock-chunk-size 2)))))
b743187d 437 ((eq prop t)
8c887c51 438 ;; PREV is the start of a region of fontified
bcacade9 439 ;; text containing AROUND. Start fontifying a
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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)))
445 (t
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))))
f1180544 456
1063efe8 457(defun jit-lock-stealth-fontify (&optional repeat)
7840ced1 458 "Fontify buffers stealthily.
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459This function is called repeatedly after Emacs has become idle for
460`jit-lock-stealth-time' seconds. Optional argument REPEAT is expected
461non-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))
7840ced1 465 (unless (or executing-kbd-macro
74614ac6 466 memory-full
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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)
7840ced1 475 minibuffer-auto-raise
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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)))))
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506
507\f
508;;; Deferred fontification.
509
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510(defun jit-lock-deferred-fontify ()
511 "Fontify what was deferred."
74614ac6 512 (when (and jit-lock-defer-buffers (not memory-full))
b743187d 513 ;; Mark the deferred regions back to `fontified = nil'
623a1226 514 (dolist (buffer jit-lock-defer-buffers)
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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)))))))))
623a1226 528 (setq jit-lock-defer-buffers nil)
b743187d 529 ;; Force fontification of the visible parts.
0902822d 530 (let ((jit-lock-defer-timer nil))
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531 ;; (message "Jit-Defer Now")
532 (sit-for 0)
533 ;; (message "Jit-Defer Done")
534 )))
f1180544 535
b743187d 536
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537(defun jit-lock-context-fontify ()
538 "Refresh fontification to take new context into account."
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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)))))))))
7b4d9d3b 567
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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.
571This is run after every buffer change. The functions are called with
572the three arguments of `after-change-functions': START END OLD-LEN.
573The extended region to refontify is returned indirectly by modifying
574the variables `jit-lock-start' and `jit-lock-end'.
575
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576Note that extending the region this way is not strictly necessary, except
577that the nature of the redisplay code tends to otherwise leave some of
578the rehighlighted text displayed with the old highlight until the next
579redisplay (see comment about repeated redisplay in `jit-lock-fontify-now').")
663e1660 580
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581(defun jit-lock-after-change (start end old-len)
582 "Mark the rest of the buffer as not fontified after a change.
583Installed on `after-change-functions'.
584START and END are the start and end of the changed text. OLD-LEN
585is the pre-change length.
586This function ensures that lines following the change will be refontified
587in case the syntax of those lines has changed. Refontification
588will take place when text is fontified stealthily."
74614ac6 589 (when (and jit-lock-mode (not memory-full))
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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))))))
f1180544 608
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609(provide 'jit-lock)
610
c4ac63d0 611;; arch-tag: 56b5de6e-f581-453b-bb97-49c39372ff9e
e8af40ee 612;;; jit-lock.el ends here