Re: C Mode: acceleration in brace deserts.

[Lennart Borgman]

Hi Alan,

Can you tell me how the cache is implemented so I can support it in MuMaMo?

Best wishes,
L


On Thu, Dec 3, 2009 at 5:21 PM, Alan Mackenzie <address@hidden> wrote:
> Hi, Richard, Yidong and Emacs!
>
> I have just committed my enhancements to CC Mode's `c-parse-state'.
> This is a central and critical part of Emacs which maintains a cache of
> the positions of certain braces, and fewer parens of other types.  As
> the position of interest in a buffer moves, this cache is updated to
> reflect the new position.
>
> In the previous version, the cache handling was severely suboptimal in
> "brace deserts", large areas of buffers entirely lacking in braces.  In
> the extreme, the algorithm was scanning from BOB every time
> c-parse-state was called.
>
> An example of such an extreme can be downloaded from
> <http://www.muc.de/~acm/AT91SAM9263_inc.h>.  To see the effect, visit
> it, do M-> and try scrolling back a page at a time.  Please compare the
> previous version with the new.
>
> The difference is noticeable even in our own .../src/lisp.h.  It is now
> noticeably less sluggish when scrolling backwards from EOB.
>
> I have tested these changes thoroughly, principly by calculating
> c-parse-state successively at an infinite number (1000) of random points
> in the buffers lisp.h and xdisp.c, then comparing "old" results with
> "new" results.  Many thanks to Stefan for `diff-refine-hunk' :-).
>
> If anybody notices anything odd, please let me know.
>
> --
> Alan Mackenzie (Nuremberg, Germany).
>
>
>