Re: jit-lock refontifies too much

[martin rudalics]

Richard wrote:
>      > That is why I suggested recording these ppss values in text
>      > properties of the first character on a line--so that they would stay
>      > around for comparison later.
>
>     That would be fine.  But recording these properties for each and every
>     line fontified would introduce too much overhead.
>
> I suspect think it is comparable to the amount of space used by
> font-lock mode now.  Maybe less.  If so, why is it too much?
>

I somewhat fell between two stools here.  With respect to my first
proposal Stefan judged ".. yet-another-text-property is a waste of
precious CPU and memory resources."

>      > Another possible advantage is: if things are not in sync for the first
>      > line after the end of the changed text, it might be in sync on a
>      > subsequent line, and that could avoid refontifying most of the lines
>      > on the screen.
>      >
>
>     I can think of two interpretations for "things are not in sync":
>
> It means "the before and after ppss values do not match".
>
> You're arguing this can't happen very easily.  Maybe that is true.
>

I didn't argue that.  Complete ppss are hardly ever "in sync" after a
modification of preceding text.  The values of ppss I need to determine
whether context changed might be in sync quite often.



Stefan wrote:
> I suggested to compare (not (equal (nth 0 ppss) (nth
> 0 jit-lock-context-ppss))) for "completeness".
>

That's reasonable.  I'll do that.