Re: Tracking buffer positions across time, without markers (was Re: PL support)

["Clément Pit-Claudel" <cpitclaudel@gmail.com>]

On 10/05/2020 20.17, Vladimir Sedach wrote:
> 
> Clément Pit-Claudel <cpitclaudel@gmail.com> writes:
>> Since we don't know beforehand what positions the subprocess will
>> return, I don't think markers can help; right?
> 
> It sounds like the fundamental thing you need here is a function from
> the integers 1 to point-max of the buffer as it was when you sent
> its contents to the sub-process, to the integers 1 to point-max of
> the buffer as it is when the sub-process returns some results.

Yes, eactly, that's what I meant when I wrote "Visual Studio has a nice API for this: there is a way to snapshot a buffer, and to translate positions between two snapshots.  In my example, this allows you to translate 0:3 in the original buffer to 7:10 in the new one."

> Another refinement is to use Stefan's idea of delimiting unmodified
> intervals and only add properties in the modified interval.

Yes, I need to think more about that one :)

> A refinement would be to put the text property on tokens. Sticky text
> properties would do the right thing when changing identifier names.

Interesting idea.  At first I worried that this would be too costly, but font-lock uses text properties and is quite fast…
But wouldn't the process of mapping back from properties to spans of text be very costly?