Re: ntemacs hangs when openning the attached file

[Alan Mackenzie <acm@muc.de>]

Hi, Eli and yu!

On Wed, May 07, 2008 at 11:48:47AM +0300, Eli Zaretskii wrote:
> > Date: Wed, 7 May 2008 12:01:38 +0800
> > From: "yu jie" <yujie052@gmail.com>
> > 
> >     The current CVS header version hangs when openning the attached file.

> No, it doesn't hang, it just takes a lot of time to visit this file.
> I measured 61 seconds on a 3GHz machine.  This file has 86406 lines,
> and uses some pretty non-standard formatting, such as this one:

The problem was that c-neutralize-syntax-in-CPP was inefficiently coded.
I've optimised it using essentially only Emacs primitives in the defun's
main loop.  It now runs almost 2 orders of magnitude faster.

Eli, I'd appreciate it very much indeed if you could review this new
code, please - earlier versions of it were peculiarly troublesome.
Thanks!

Here's the patch:


*** cc-mode.el~	2008-05-23 20:42:45.653994480 +0000
--- cc-mode.el	2008-05-23 20:50:43.941283760 +0000
***************
*** 837,863 ****
    ;;
    ;; This function is the C/C++/ObjC value of `c-before-font-lock-function'.
    ;;
    ;; This function might do invisible changes.
!   (c-save-buffer-state (limits mbeg+1 beg end)
!     ;; First calculate the region, possibly to be extended.
!     (setq beg (min begg c-old-BOM))
      (goto-char endd)
!     (when (c-beginning-of-macro)
!       (c-end-of-macro))
      (setq end (max (+ (- c-old-EOM old-len) (- endd begg))
  		   (point)))
      ;; Clear all old punctuation properties
      (c-clear-char-property-with-value beg end 'syntax-table '(1))
  
      (goto-char beg)
      (while (and (< (point) end)
  		(search-forward-regexp c-anchored-cpp-prefix end t))
        ;; If we've found a "#" inside a string/comment, ignore it.
!       (if (setq limits (c-literal-limits))
! 	  (goto-char (cdr limits))
  	(setq mbeg+1 (point))
  	(c-end-of-macro)	  ; Do we need to go forward 1 char here?  No!
! 	(c-neutralize-CPP-line mbeg+1 (point))))))
  
  (defun c-before-change (beg end)
    ;; Function to be put on `before-change-function'.  Primarily, this calls
--- 837,881 ----
    ;;
    ;; This function is the C/C++/ObjC value of `c-before-font-lock-function'.
    ;;
+   ;; Note: SPEED _MATTERS_ IN THIS FUNCTION!!!
+   ;; 
    ;; This function might do invisible changes.
!   (c-save-buffer-state (limits mbeg+1 beg end pps-position pps-state)
!     ;; First determine the region, (beg end), which may need "neutralizing".
!     ;; This may not start inside a string or comment, or a macro.
!     (goto-char begg)
!     (if (setq limits (c-literal-limits))
! 	(goto-char (cdr limits)))   ; go forward out of any string or comment.
!     (c-beginning-of-macro)
!     (setq beg (min (point) c-old-BOM))
! 
      (goto-char endd)
!     (if (setq limits (c-literal-limits))
! 	(goto-char (car limits)))  ; go backward out of any string or comment.
!     (if (c-beginning-of-macro)
! 	(c-end-of-macro))
      (setq end (max (+ (- c-old-EOM old-len) (- endd begg))
  		   (point)))
+ 
      ;; Clear all old punctuation properties
      (c-clear-char-property-with-value beg end 'syntax-table '(1))
  
      (goto-char beg)
+     (setq pps-position beg  pps-state nil)
      (while (and (< (point) end)
  		(search-forward-regexp c-anchored-cpp-prefix end t))
        ;; If we've found a "#" inside a string/comment, ignore it.
!       (setq pps-state
! 	    (parse-partial-sexp pps-position (point) nil nil pps-state)
! 	    pps-position (point))
!       (unless (or (nth 3 pps-state)	; in a string?
! 		  (nth 4 pps-state))	; in a comment?
  	(setq mbeg+1 (point))
  	(c-end-of-macro)	  ; Do we need to go forward 1 char here?  No!
! 	(c-neutralize-CPP-line mbeg+1 (point))
! 	(setq pps-state
! 	      (parse-partial-sexp pps-position (point) nil nil pps-state)
! 	      pps-position (point))))))
  
  (defun c-before-change (beg end)
    ;; Function to be put on `before-change-function'.  Primarily, this calls


-- 
Alan Mackenzie (Nuremberg, Germany).