Re: emacs-tree-sitter and Emacs

[Michael Welsh Duggan]

Eli Zaretskii <address@hidden> writes:

>> From: Stephen Leake <address@hidden>
>> Date: Wed, 01 Apr 2020 11:51:40 -0800
>> 
>> Eli Zaretskii <address@hidden> writes:
>> 
>> > Can you tell in more detail why you need to rely on these hooks?  They
>> > shouldn't be necessary, AFAIU.  
>> 
>> It is an optimization choice.
>> 
>> In an unmodified buffer, that is smaller than 100,000 characters
>> (default setting of wisi-partial-parse-threshold), the entire buffer is
>> parsed once; that applies faces to all the Ada identifiers that need
>> faces (standard font-lock regexp handles the reserved words). Then when
>> font-lock fontifies a region, no parsing is needed.
>
> But why do you need that initial full parse in the first place?  Is
> parsing parts of the buffer so much harder?

I would think that you at least need to parse everything displayed and
everything before what is displayed.  (You need all prior context.  What
if someone opened a comment on line 1 and hasn't closed it, for
example?)  I don't, however, see a reason you couldn't defer sending the
rest until afterward, any more than you would have to if the file were
being typed in, one line at a time.

-- 
Michael Welsh Duggan
(address@hidden)