Re: How to add pseudo vector types

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Wed, 28 Jul 2021 12:36:33 -0400
> Cc: Eli Zaretskii <eliz@gnu.org>,
>  Clément Pit-Claudel <cpitclaudel@gmail.com>,
>  monnier@iro.umontreal.ca, emacs-devel <emacs-devel@gnu.org>
> 
> > What, exactly, will the buffer-text fetch code do if tree-sitter
> > violates the narrowing (by some error in tree-sitter or user code)?
> > throw an exception? return a null string?
> 
> In my current implementation, if tree-sitter access buffer content outside of 
> narrowed region, it reads whitespaces, if it access buffer content outside of 
> the buffer, it reads null string. Neither case throws an error.

What does TS expect the reader function to return when it hits the
beginning or end of buffer text?  I think we should behave the same
when it tries to go beyond the accessible portion.  There should be no
difference between going beyond the restriction and going beyond EOB.