Re: vim-7.4.389 UI extremely sluggish with custom syntax highlighting plugins

Christian Brabandt wrote:

> Hi Bram!
>
> On Mi, 13 Aug 2014, Bram Moolenaar wrote:
>
> >
> > Christian Brabandt wrote:
> >
> > > > > On Sa, 09 Aug 2014, Bram Moolenaar wrote:
> > > > > > David Barnett wrote:
> > > > > >
> > > > > > > Looks like it's patch 7.4.362:
> > > > > > >
> > > > > > > Problem: When matchaddpos() uses a length smaller than the number of
> > > > > > > bytes
> > > > > > > in the (last) character the highlight continues until the end of
> > > > > > > the line.
> > > > > > > Solution: Change condition from equal to larger-or-equal.
> > > > > > > Files: src/screen.c
> > > > > > >
> > > > > > >
> > > > > > > It's a very small change but apparently problematic. Can it be reverted or
> > > > > > > rethought?
> > > > > >
> > > > > > I'm glad you could pinpoint it. I assumed that when the condition
> > > > > > evaluates to true the match information would be updated. But perhaps
> > > > > > that doesn't happen in this case and it searches for a match every time.
> > > > > >
> > > > > > Needs some debugging to figure out what happens. What matches does this
> > > > > > plugin add when it's slow?
> > > > >
> > > > > Perhaps it is better to revert that patch and make sure, highlighting
> > > > > gets only applied, if there is a match at the actual position?
> > > > >
> > > > > diff --git a/src/screen.c b/src/screen.c
> > > [...]
> > > >
> > > > I haven't tried it, but it looks like this only avoids highlighting
> > > > positions after the endcol when "v" and shl->endcol aren't exactly the
> > > > same (which can happen for multi-byte characters), but it doesn't update
> > > > the state, thus a next match might be missed.
> > >
> > > Yes, that is what patch 7.3.362 tried to fix, isn't it?
> >
> > So your patch doesn't work. Try this:
> >
> > highlight MyGroup ctermbg=green guibg=green
> > let m = matchaddpos("MyGroup", [[4, 24, 2], [4, 30, 2]])
> >
> > " asdfasdfasdfasdfasdfas℅fasdfasdfasdfasdf
> >
> > Before pach 362 it would highlight everything from column 24.
> > After the fix it looks OK, but we get complaints about slowness.
> > After your fix only the first match shows up.
>
> I don't see that here (screenshot attached)

Did you put a multi-byte character at the end of the first match?

> But anyway, this raises the question again, why matchaddpos() accepts a
> list of positions (but only 8 items), while all other functions usually
> only accept 1 position.

It's used for the matchparen plugin. The idea is that it's useful for
other plugins as well.

--
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/// Bram Moolenaar -- Bram@Moolenaar.net -- http://www.Moolenaar.net \\\
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