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bug#35316: 26.2; Emacs lags in c++-mode buffer when editing with iedit-m
From: |
Stefan Monnier |
Subject: |
bug#35316: 26.2; Emacs lags in c++-mode buffer when editing with iedit-mode on |
Date: |
Fri, 19 Apr 2019 12:20:14 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
> Reproducing steps:
> 1. emacs -Q
> 2. Eval code: (add-to-list 'package-archives '("melpa" .
> "https://melpa.org/packages/“))
> 3. install the package iedit (version from melpa)
> 4. open the attachment c++ file, and goto line 262 and column 17. cursor
> will be on word “subsession"
> 5. M-x narrow-to-defun
> 6. M-x iedit-mode
> 7. M-x widen
> 8. You will see the lag when inputting chars.
This seems to be a good use case for my syntax-propertize patch.
I just tried it on your test case and while there is still a slight slow
down, it seemed to be much less problematic.
BEWARE: it likely introduces bugs.
Stefan
diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index 49268c4482..31f5ecdfdb 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -506,6 +506,8 @@ c-just-done-before-change
;; and `after-change-functions'. Note that this variable is not set when
;; `c-before-change' is invoked by a change to text properties.
+(defvar c--use-syntax-propertize t)
+
(defun c-basic-common-init (mode default-style)
"Do the necessary initialization for the syntax handling routines
and the line breaking/filling code. Intended to be used by other
@@ -648,12 +650,17 @@ c-basic-common-init
;; Install the functions that ensure that various internal caches
;; don't become invalid due to buffer changes.
- (when (featurep 'xemacs)
- (make-local-hook 'before-change-functions)
- (make-local-hook 'after-change-functions))
- (add-hook 'before-change-functions 'c-before-change nil t)
- (setq c-just-done-before-change nil)
- (add-hook 'after-change-functions 'c-after-change nil t)
+ (if c--use-syntax-propertize
+ (setq-local syntax-propertize-function
+ (lambda (start end)
+ (c-before-change start (point-max))
+ (c-after-change start end (- end start))))
+ (when (featurep 'xemacs)
+ (make-local-hook 'before-change-functions)
+ (make-local-hook 'after-change-functions))
+ (add-hook 'before-change-functions 'c-before-change nil t)
+ (setq c-just-done-before-change nil)
+ (add-hook 'after-change-functions 'c-after-change nil t))
(when (boundp 'font-lock-extend-after-change-region-function)
(set (make-local-variable 'font-lock-extend-after-change-region-function)
'c-extend-after-change-region))) ; Currently (2009-05) used by all
@@ -711,15 +718,17 @@ c-common-init
(widen)
(setq c-new-BEG (point-min))
(setq c-new-END (point-max))
- (save-excursion
- (let (before-change-functions after-change-functions)
- (mapc (lambda (fn)
- (funcall fn (point-min) (point-max)))
- c-get-state-before-change-functions)
- (mapc (lambda (fn)
- (funcall fn (point-min) (point-max)
- (- (point-max) (point-min))))
- c-before-font-lock-functions))))
+ (unless c--use-syntax-propertize
+ (save-excursion
+ (let (before-change-functions after-change-functions)
+ (mapc (lambda (fn)
+ (funcall fn (point-min) (point-max)))
+ c-get-state-before-change-functions)
+ (mapc (lambda (fn)
+ (funcall fn (point-min) (point-max)
+ (- (point-max) (point-min))))
+ c-before-font-lock-functions)
+ ))))
(set (make-local-variable 'outline-regexp) "[^#\n\^M]")
(set (make-local-variable 'outline-level) 'c-outline-level)
@@ -1954,6 +1963,12 @@ c-font-lock-fontify-region
;;
;; Type a space in the first blank line, and the fontification of the next
;; line was fouled up by context fontification.
+ (when c--use-syntax-propertize
+ ;; This should also update c-new-END and c-new-BEG.
+ (syntax-propertize end)
+ ;; FIXME: Apparently `c-new-END' may be left unchanged to a stale value,
+ ;; presumably when the buffer gets truncated.
+ (if (> c-new-END (point-max)) (setq c-new-END (point-max))))
(let (new-beg new-end new-region case-fold-search)
(if (and c-in-after-change-fontification
(< beg c-new-END) (> end c-new-BEG))
@@ -1992,7 +2007,8 @@ c-font-lock-fontify-region
(defun c-after-font-lock-init ()
;; Put on `font-lock-mode-hook'. This function ensures our after-change
;; function will get executed before the font-lock one.
- (when (memq #'c-after-change after-change-functions)
+ (when (and c--use-syntax-propertize
+ (memq #'c-after-change after-change-functions))
(remove-hook 'after-change-functions #'c-after-change t)
(add-hook 'after-change-functions #'c-after-change nil t)))
@@ -2046,11 +2062,14 @@ c-extend-after-change-region
(when (eq font-lock-support-mode 'jit-lock-mode)
(save-restriction
(widen)
+ ;; FIXME: This presumes that c-new-BEG and c-new-END have been set
+ ;; I guess from the before-change-function.
(c-save-buffer-state () ; Protect the undo-list from put-text-property.
(if (< c-new-BEG beg)
(put-text-property c-new-BEG beg 'fontified nil))
(if (> c-new-END end)
- (put-text-property end c-new-END 'fontified nil)))))
+ (put-text-property end (min c-new-END (point-max))
+ 'fontified nil)))))
(cons c-new-BEG c-new-END))
;; Emacs < 22 and XEmacs