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532 lines
20 KiB
EmacsLisp
532 lines
20 KiB
EmacsLisp
;;; jit-lock.el --- just-in-time fontification
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;; Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc.
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;; Author: Gerd Moellmann <gerd@gnu.org>
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;; Keywords: faces files
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; Just-in-time fontification, triggered by C redisplay code.
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;;; Code:
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(eval-when-compile
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(defmacro with-buffer-unmodified (&rest body)
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"Eval BODY, preserving the current buffer's modified state."
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(let ((modified (make-symbol "modified")))
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`(let ((,modified (buffer-modified-p)))
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(unwind-protect
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(progn ,@body)
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(unless ,modified
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(restore-buffer-modified-p nil))))))
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(defmacro with-buffer-prepared-for-jit-lock (&rest body)
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"Execute BODY in current buffer, overriding several variables.
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Preserves the `buffer-modified-p' state of the current buffer."
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`(with-buffer-unmodified
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(let ((buffer-undo-list t)
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(inhibit-read-only t)
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(inhibit-point-motion-hooks t)
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(inhibit-modification-hooks t)
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deactivate-mark
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buffer-file-name
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buffer-file-truename)
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,@body))))
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;;; Customization.
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(defcustom jit-lock-chunk-size 500
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"*Jit-lock chunks of this many characters, or smaller."
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:type 'integer
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:group 'jit-lock)
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(defcustom jit-lock-stealth-time 3
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"*Time in seconds to wait before beginning stealth fontification.
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Stealth fontification occurs if there is no input within this time.
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If nil, stealth fontification is never performed.
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The value of this variable is used when JIT Lock mode is turned on."
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:type '(choice (const :tag "never" nil)
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(number :tag "seconds"))
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:group 'jit-lock)
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(defcustom jit-lock-stealth-nice 0.125
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"*Time in seconds to pause between chunks of stealth fontification.
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Each iteration of stealth fontification is separated by this amount of time,
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thus reducing the demand that stealth fontification makes on the system.
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If nil, means stealth fontification is never paused.
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To reduce machine load during stealth fontification, at the cost of stealth
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taking longer to fontify, you could increase the value of this variable.
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See also `jit-lock-stealth-load'."
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:type '(choice (const :tag "never" nil)
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(number :tag "seconds"))
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:group 'jit-lock)
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(defcustom jit-lock-stealth-load
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(if (condition-case nil (load-average) (error)) 200)
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"*Load in percentage above which stealth fontification is suspended.
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Stealth fontification pauses when the system short-term load average (as
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returned by the function `load-average' if supported) goes above this level,
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thus reducing the demand that stealth fontification makes on the system.
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If nil, means stealth fontification is never suspended.
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To reduce machine load during stealth fontification, at the cost of stealth
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taking longer to fontify, you could reduce the value of this variable.
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See also `jit-lock-stealth-nice'."
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:type (if (condition-case nil (load-average) (error))
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'(choice (const :tag "never" nil)
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(integer :tag "load"))
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'(const :format "%t: unsupported\n" nil))
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:group 'jit-lock)
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(defcustom jit-lock-stealth-verbose nil
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"*If non-nil, means stealth fontification should show status messages."
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:type 'boolean
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:group 'jit-lock)
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(defcustom jit-lock-defer-contextually 'syntax-driven
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"*If non-nil, means deferred fontification should be syntactically true.
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If nil, means deferred fontification occurs only on those lines modified. This
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means where modification on a line causes syntactic change on subsequent lines,
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those subsequent lines are not refontified to reflect their new context.
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If t, means deferred fontification occurs on those lines modified and all
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subsequent lines. This means those subsequent lines are refontified to reflect
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their new syntactic context, either immediately or when scrolling into them.
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If any other value, e.g., `syntax-driven', means deferred syntactically true
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fontification occurs only if syntactic fontification is performed using the
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buffer mode's syntax table, i.e., only if `font-lock-keywords-only' is nil.
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The value of this variable is used when JIT Lock mode is turned on."
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:type '(choice (const :tag "never" nil)
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(const :tag "always" t)
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(other :tag "syntax-driven" syntax-driven))
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:group 'jit-lock)
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(defcustom jit-lock-defer-time nil ;; 0.25
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"Idle time after which deferred fontification should take place.
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If nil, fontification is not deferred."
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:group 'jit-lock
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:type '(choice (const :tag "never" nil)
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(number :tag "seconds")))
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;;; Variables that are not customizable.
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(defvar jit-lock-mode nil
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"Non-nil means Just-in-time Lock mode is active.")
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(make-variable-buffer-local 'jit-lock-mode)
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(defvar jit-lock-functions nil
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"Functions to do the actual fontification.
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They are called with two arguments: the START and END of the region to fontify.")
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(make-variable-buffer-local 'jit-lock-functions)
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(defvar jit-lock-first-unfontify-pos nil
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"Consider text after this position as contextually unfontified.
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If nil, contextual fontification is disabled.")
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(make-variable-buffer-local 'jit-lock-first-unfontify-pos)
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(defvar jit-lock-stealth-timer nil
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"Timer for stealth fontification in Just-in-time Lock mode.")
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(defvar jit-lock-defer-timer nil
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"Timer for deferred fontification in Just-in-time Lock mode.")
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(defvar jit-lock-buffers nil
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"List of buffers with pending deferred fontification.")
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;;; JIT lock mode
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(defun jit-lock-mode (arg)
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"Toggle Just-in-time Lock mode.
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Turn Just-in-time Lock mode on if and only if ARG is non-nil.
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Enable it automatically by customizing group `font-lock'.
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When Just-in-time Lock mode is enabled, fontification is different in the
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following ways:
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- Demand-driven buffer fontification triggered by Emacs C code.
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This means initial fontification of the whole buffer does not occur.
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Instead, fontification occurs when necessary, such as when scrolling
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through the buffer would otherwise reveal unfontified areas. This is
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useful if buffer fontification is too slow for large buffers.
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- Stealthy buffer fontification if `jit-lock-stealth-time' is non-nil.
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This means remaining unfontified areas of buffers are fontified if Emacs has
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been idle for `jit-lock-stealth-time' seconds, while Emacs remains idle.
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This is useful if any buffer has any deferred fontification.
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- Deferred context fontification if `jit-lock-defer-contextually' is
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non-nil. This means fontification updates the buffer corresponding to
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true syntactic context, after `jit-lock-stealth-time' seconds of Emacs
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idle time, while Emacs remains idle. Otherwise, fontification occurs
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on modified lines only, and subsequent lines can remain fontified
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corresponding to previous syntactic contexts. This is useful where
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strings or comments span lines.
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Stealth fontification only occurs while the system remains unloaded.
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If the system load rises above `jit-lock-stealth-load' percent, stealth
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fontification is suspended. Stealth fontification intensity is controlled via
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the variable `jit-lock-stealth-nice'."
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(setq jit-lock-mode arg)
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(cond (;; Turn Just-in-time Lock mode on.
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jit-lock-mode
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;; Mark the buffer for refontification.
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(jit-lock-refontify)
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;; Install an idle timer for stealth fontification.
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(when (and jit-lock-stealth-time (null jit-lock-stealth-timer))
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(setq jit-lock-stealth-timer
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(run-with-idle-timer jit-lock-stealth-time t
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'jit-lock-stealth-fontify)))
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;; Init deferred fontification timer.
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(when (and jit-lock-defer-time (null jit-lock-defer-timer))
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(setq jit-lock-defer-timer
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(run-with-idle-timer jit-lock-defer-time t
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'jit-lock-deferred-fontify)))
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;; Initialize deferred contextual fontification if requested.
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(when (eq jit-lock-defer-contextually t)
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(setq jit-lock-first-unfontify-pos
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(or jit-lock-first-unfontify-pos (point-max))))
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;; Setup our hooks.
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(add-hook 'after-change-functions 'jit-lock-after-change nil t)
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(add-hook 'fontification-functions 'jit-lock-function))
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;; Turn Just-in-time Lock mode off.
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(t
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;; Cancel our idle timers.
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(when (and (or jit-lock-stealth-timer jit-lock-defer-timer)
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;; Only if there's no other buffer using them.
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(not (catch 'found
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(dolist (buf (buffer-list))
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(with-current-buffer buf
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(when jit-lock-mode (throw 'found t)))))))
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(when jit-lock-stealth-timer
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(cancel-timer jit-lock-stealth-timer)
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(setq jit-lock-stealth-timer nil))
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(when jit-lock-defer-timer
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(cancel-timer jit-lock-defer-timer)
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(setq jit-lock-defer-timer nil)))
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;; Remove hooks.
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(remove-hook 'after-change-functions 'jit-lock-after-change t)
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(remove-hook 'fontification-functions 'jit-lock-function))))
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;;;###autoload
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(defun jit-lock-register (fun &optional contextual)
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"Register FUN as a fontification function to be called in this buffer.
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FUN will be called with two arguments START and END indicating the region
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that needs to be (re)fontified.
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If non-nil, CONTEXTUAL means that a contextual fontification would be useful."
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(add-hook 'jit-lock-functions fun nil t)
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(when (and contextual jit-lock-defer-contextually)
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(set (make-local-variable 'jit-lock-defer-contextually) t))
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(jit-lock-mode t))
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(defun jit-lock-unregister (fun)
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"Unregister FUN as a fontification function.
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Only applies to the current buffer."
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(remove-hook 'jit-lock-functions fun t)
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(unless jit-lock-functions (jit-lock-mode nil)))
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;; This function is used to prevent font-lock-fontify-buffer from
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;; fontifying eagerly the whole buffer. This is important for
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;; things like CWarn mode which adds/removes a few keywords and
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;; does a refontify (which takes ages on large files).
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(defun jit-lock-refontify (&optional beg end)
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"Force refontification of the region BEG..END (default whole buffer)."
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(with-buffer-prepared-for-jit-lock
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(save-restriction
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(widen)
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(put-text-property (or beg (point-min)) (or end (point-max))
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'fontified nil))))
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;;; On demand fontification.
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(defun jit-lock-function (start)
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"Fontify current buffer starting at position START.
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This function is added to `fontification-functions' when `jit-lock-mode'
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is active."
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(when jit-lock-mode
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(if (null jit-lock-defer-time)
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;; No deferral.
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(jit-lock-fontify-now start (+ start jit-lock-chunk-size))
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;; Record the buffer for later fontification.
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(unless (memq (current-buffer) jit-lock-buffers)
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(push (current-buffer) jit-lock-buffers))
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;; Mark the area as defer-fontified so that the redisplay engine
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;; is happy and so that the idle timer can find the places to fontify.
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(with-buffer-prepared-for-jit-lock
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(put-text-property start
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(next-single-property-change
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start 'fontified nil
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(min (point-max) (+ start jit-lock-chunk-size)))
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'fontified 'defer)))))
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(defun jit-lock-fontify-now (&optional start end)
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"Fontify current buffer from START to END.
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Defaults to the whole buffer. END can be out of bounds."
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(with-buffer-prepared-for-jit-lock
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(save-excursion
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(unless start (setq start (point-min)))
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(setq end (if end (min end (point-max)) (point-max)))
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;; This did bind `font-lock-beginning-of-syntax-function' to
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;; nil at some point, for an unknown reason. Don't do this; it
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;; can make highlighting slow due to expensive calls to
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;; `parse-partial-sexp' in function
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;; `font-lock-fontify-syntactically-region'. Example: paging
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;; from the end of a buffer to its start, can do repeated
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;; `parse-partial-sexp' starting from `point-min', which can
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;; take a long time in a large buffer.
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(let (next)
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(save-match-data
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;; Fontify chunks beginning at START. The end of a
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;; chunk is either `end', or the start of a region
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;; before `end' that has already been fontified.
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(while start
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;; Determine the end of this chunk.
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(setq next (or (text-property-any start end 'fontified t)
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end))
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;; Decide which range of text should be fontified.
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;; The problem is that START and NEXT may be in the
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;; middle of something matched by a font-lock regexp.
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;; Until someone has a better idea, let's start
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;; at the start of the line containing START and
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;; stop at the start of the line following NEXT.
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(goto-char next) (setq next (line-beginning-position 2))
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(goto-char start) (setq start (line-beginning-position))
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;; Fontify the chunk, and mark it as fontified.
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;; We mark it first, to make sure that we don't indefinitely
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;; re-execute this fontification if an error occurs.
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(put-text-property start next 'fontified t)
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(run-hook-with-args 'jit-lock-functions start next)
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;; Find the start of the next chunk, if any.
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(setq start (text-property-any next end 'fontified nil))))))))
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;;; Stealth fontification.
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(defsubst jit-lock-stealth-chunk-start (around)
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"Return the start of the next chunk to fontify around position AROUND..
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Value is nil if there is nothing more to fontify."
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(if (zerop (buffer-size))
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nil
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(save-restriction
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(widen)
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(let* ((next (text-property-not-all around (point-max) 'fontified t))
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(prev (previous-single-property-change around 'fontified))
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(prop (get-text-property (max (point-min) (1- around))
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'fontified))
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(start (cond
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((null prev)
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;; There is no property change between AROUND
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;; and the start of the buffer. If PROP is
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;; non-nil, everything in front of AROUND is
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;; fontified, otherwise nothing is fontified.
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(if (eq prop t)
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nil
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(max (point-min)
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(- around (/ jit-lock-chunk-size 2)))))
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((eq prop t)
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;; PREV is the start of a region of fontified
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;; text containing AROUND. Start fontifying a
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;; chunk size before the end of the unfontified
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;; region in front of that.
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(max (or (previous-single-property-change prev 'fontified)
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(point-min))
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(- prev jit-lock-chunk-size)))
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(t
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;; PREV is the start of a region of unfontified
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;; text containing AROUND. Start at PREV or
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;; chunk size in front of AROUND, whichever is
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;; nearer.
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(max prev (- around jit-lock-chunk-size)))))
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(result (cond ((null start) next)
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((null next) start)
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((< (- around start) (- next around)) start)
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(t next))))
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result))))
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(defun jit-lock-stealth-fontify ()
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"Fontify buffers stealthily.
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This functions is called after Emacs has been idle for
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`jit-lock-stealth-time' seconds."
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;; I used to check `inhibit-read-only' here, but I can't remember why. -stef
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(unless (or executing-kbd-macro
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(window-minibuffer-p (selected-window)))
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(let ((buffers (buffer-list))
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minibuffer-auto-raise
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message-log-max)
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(while (and buffers (not (input-pending-p)))
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(let ((buffer (car buffers)))
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(setq buffers (cdr buffers))
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(with-current-buffer buffer
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(when jit-lock-mode
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;; This is funny. Calling sit-for with 3rd arg non-nil
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;; so that it doesn't redisplay, internally calls
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;; wait_reading_process_input also with a parameter
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;; saying "don't redisplay." Since this function here
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;; is called periodically, this effectively leads to
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;; process output not being redisplayed at all because
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;; redisplay_internal is never called. (That didn't
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;; work in the old redisplay either.) So, we learn that
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;; we mustn't call sit-for that way here. But then, we
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;; have to be cautious not to call sit-for in a widened
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;; buffer, since this could display hidden parts of that
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;; buffer. This explains the seemingly weird use of
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;; save-restriction/widen here.
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(with-temp-message (if jit-lock-stealth-verbose
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(concat "JIT stealth lock "
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(buffer-name)))
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;; Perform deferred unfontification, if any.
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(when jit-lock-first-unfontify-pos
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(save-restriction
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(widen)
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(when (and (>= jit-lock-first-unfontify-pos (point-min))
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(< jit-lock-first-unfontify-pos (point-max)))
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;; If we're in text that matches a complex multi-line
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;; font-lock pattern, make sure the whole text will be
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;; redisplayed eventually.
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(when (get-text-property jit-lock-first-unfontify-pos
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'jit-lock-defer-multiline)
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(setq jit-lock-first-unfontify-pos
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(or (previous-single-property-change
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jit-lock-first-unfontify-pos
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'jit-lock-defer-multiline)
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(point-min))))
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(with-buffer-prepared-for-jit-lock
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(remove-text-properties
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jit-lock-first-unfontify-pos (point-max)
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'(fontified nil jit-lock-defer-multiline nil)))
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(setq jit-lock-first-unfontify-pos (point-max)))))
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;; In the following code, the `sit-for' calls cause a
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;; redisplay, so it's required that the
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;; buffer-modified flag of a buffer that is displayed
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;; has the right value---otherwise the mode line of
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;; an unmodified buffer would show a `*'.
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(let (start
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(nice (or jit-lock-stealth-nice 0))
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(point (point-min)))
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(while (and (setq start
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(jit-lock-stealth-chunk-start point))
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(sit-for nice))
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;; fontify a block.
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(jit-lock-fontify-now start (+ start jit-lock-chunk-size))
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;; If stealth jit-locking is done backwards, this leads to
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;; excessive O(n^2) refontification. -stef
|
||
;; (when (>= jit-lock-first-unfontify-pos start)
|
||
;; (setq jit-lock-first-unfontify-pos end))
|
||
|
||
;; Wait a little if load is too high.
|
||
(when (and jit-lock-stealth-load
|
||
(> (car (load-average)) jit-lock-stealth-load))
|
||
(sit-for (or jit-lock-stealth-time 30)))))))))))))
|
||
|
||
|
||
|
||
;;; Deferred fontification.
|
||
|
||
(defun jit-lock-deferred-fontify ()
|
||
"Fontify what was deferred."
|
||
(when jit-lock-buffers
|
||
;; Mark the deferred regions back to `fontified = nil'
|
||
(dolist (buffer jit-lock-buffers)
|
||
(when (buffer-live-p buffer)
|
||
(with-current-buffer buffer
|
||
;; (message "Jit-Defer %s" (buffer-name))
|
||
(with-buffer-prepared-for-jit-lock
|
||
(let ((pos (point-min)))
|
||
(while
|
||
(progn
|
||
(when (eq (get-text-property pos 'fontified) 'defer)
|
||
(put-text-property
|
||
pos (setq pos (next-single-property-change
|
||
pos 'fontified nil (point-max)))
|
||
'fontified nil))
|
||
(setq pos (next-single-property-change pos 'fontified)))))))))
|
||
(setq jit-lock-buffers nil)
|
||
;; Force fontification of the visible parts.
|
||
(let ((jit-lock-defer-time nil))
|
||
;; (message "Jit-Defer Now")
|
||
(sit-for 0)
|
||
;; (message "Jit-Defer Done")
|
||
)))
|
||
|
||
|
||
(defun jit-lock-after-change (start end old-len)
|
||
"Mark the rest of the buffer as not fontified after a change.
|
||
Installed on `after-change-functions'.
|
||
START and END are the start and end of the changed text. OLD-LEN
|
||
is the pre-change length.
|
||
This function ensures that lines following the change will be refontified
|
||
in case the syntax of those lines has changed. Refontification
|
||
will take place when text is fontified stealthily."
|
||
(when jit-lock-mode
|
||
(save-excursion
|
||
(with-buffer-prepared-for-jit-lock
|
||
;; It's important that the `fontified' property be set from the
|
||
;; beginning of the line, else font-lock will properly change the
|
||
;; text's face, but the display will have been done already and will
|
||
;; be inconsistent with the buffer's content.
|
||
(goto-char start)
|
||
(setq start (line-beginning-position))
|
||
|
||
;; If we're in text that matches a multi-line font-lock pattern,
|
||
;; make sure the whole text will be redisplayed.
|
||
;; I'm not sure this is ever necessary and/or sufficient. -stef
|
||
(when (get-text-property start 'font-lock-multiline)
|
||
(setq start (or (previous-single-property-change
|
||
start 'font-lock-multiline)
|
||
(point-min))))
|
||
|
||
;; Make sure we change at least one char (in case of deletions).
|
||
(setq end (min (max end (1+ start)) (point-max)))
|
||
;; Request refontification.
|
||
(put-text-property start end 'fontified nil))
|
||
;; Mark the change for deferred contextual refontification.
|
||
(when jit-lock-first-unfontify-pos
|
||
(setq jit-lock-first-unfontify-pos
|
||
(min jit-lock-first-unfontify-pos start))))))
|
||
|
||
(provide 'jit-lock)
|
||
|
||
;;; jit-lock.el ends here
|