Subject: Re: 26.2.90; [PATCH] Speed up 'csv-align-fields'

From: Stefan Monnier <[email-masked]>
Date: Tue, 17 Sep 2019 15:12:28 -0400

>> Of the whole file?  No: instead you'd only use the max of the columns that
>> you've seen so far.  When it increases (thus invalidating
>> alignment-overlays already created), you just "flush" those overlays and
>> rebuild them.
> Wouldn't then the columns appear to jump about whenever a new max width
> is discovered?

Yes, but that should only happen as part of a scroll or similar
"significant" visual change anyway.

> I also guess you'd lose the ability to do e.g.
> C-u 1000 C-n and stay in the same column?

Probably, yes.  Seems like a minor issue to me.

>> Maybe we could get yet more speedup by making it possible to pass to
>> `current-column` (or a new C function) a start position along with its
>> column, so we'd avoid re-traversing the part of the line that we've
>> already processed.
> I think that sounds like a good idea; then my ugly "fast-current-column"

> Could this track be something worth exploring further?

Your call,

        Stefan