Re: Exposing buffer text modifications to Lisp (was: Tree-sitter integration on feature/tree-sitter)

[Ihor Radchenko]

Eli Zaretskii <eliz@gnu.org> writes:

>> (headline
>>   (:raw-value "test headline" :begin 292 :end 314 ... :tags ("tag") ... 
>> :parent (...))
>>   ;; no children
>>    )
>> 
>> Upon modifying text inside the headline, we need to update :begin/:end
>> properties to reflect the new headline boundaries in buffer and possibly
>> update headline properties (e.g. :tags).
>> 
>> The same should be done for all the elements containing the headline.
>
> Where you care about changes in buffer positions of the AST elements,
> markers should take care of most, if not all, of them.  I presume you
> already do use markers wherever possible? if not, why not?  Or what am
> I missing?

Because lots of markers degrade Emacs regex search performance
tremendously.

See https://list.orgmode.org/orgmode/scedec$2g0$1@ciao.gmane.io/
and https://orgmode.org/list/87y21wkdwu.fsf@localhost

>> Missing any significant change (the one involving terminal symbols or
>> changing region length) will make the AST invalid.
>
> Why would you miss significant changes if you base your implementation
> on buffer-modification hooks?  If there are some situations where
> buffer text is modified in ways that are significant for the update
> of the AST, but buffer-modification hooks are NOT called, please
> describe some of those situations, so we will have something concrete
> to talk about.

The situation is third-party code doing bloody murder with

(with-silent-modifications
 (insert "Some text not triggering modification hooks))

Another scenario is modifying text in indirect buffers created with
make-indirect-buffer. (where there is no chance to install
before/after-change-functions via clone-indirect-buffer-hook).

Best,
Ihor