Re: Semantic font-lock for Java

[Eli Zaretskii <eliz@gnu.org>]

> From: Anand Tamariya <atamariya@gmail.com>
> Date: Wed, 22 Jan 2020 10:43:21 +0530
> Cc: emacs-devel@gnu.org
> 
>  This seems to be a complete forked repository.  Is it possible to show
>  a patch relative to the current master?
> 
> https://gitlab.com/atamariya/emacs/compare/v0.5...dev

Thanks.

> Most relevant changes are in lisp/cedet/semantic/java.el . Other minor changes are for disabling jit-lock.
> - Font lock setup : semantic-font-lock-mode()
> - Fontify region function: extract()
> - Helper function: semantic-fontify-tag()

I don't think I understand the reasons for the changes in font-lock.el
and cc-mode.el.  Can you explain?

Also, what do you mean by "disable jit-lock"?  Where does that happen?
And if you disable jit-lock, does that mean Emacs will no longer
fontify only the portions of the window it is about to display?

>  you could run a benchmark of scrolling through a
>  large source file top to bottom, and show the results in terms of time
>  and number of GCs.
> 
> Not sure how to do this. If you can help me with steps, I can collect the data. 

I find this function useful:

  (defun scroll-up-benchmark ()
    (interactive)
    (let ((oldgc gcs-done)
	  (oldtime (float-time)))
      (condition-case nil (while t (scroll-up) (redisplay))
	(error (message "GCs: %d Elapsed time: %f seconds"
			(- gcs-done oldgc) (- (float-time) oldtime))))))

Run it after loading a file, and look at the times with the default
font-lock and with your modifications.