Re: Call for volunteers: add tree-sitter support to major modes

[Yuan Fu <casouri@gmail.com>]

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> On Oct 17, 2022, at 8:24 PM, Po Lu <luangruo@yahoo.com> wrote:
> 
> Alan Mackenzie <acm@muc.de> writes:
> 
>> Generally, that the replacement of CC Mode's engine with tree-sitter is
>> a good idea; CC Mode as it currently is is too much work to maintain,
>> and in the long run is unsustainable.
>> 
>> At the same time, I have no idea how good tree-sitter's grammars for CC
>> Mode's modes are.  If I understand rightly, a call to TS requires start
>> and end buffer positions to be calculated by Emacs rather than TS
>> itself.  This might reduce some of the expected speed gain.
>> 
>> I would like to keep all of CC Mode's user features in the new mode, if
>> at all possible.  I don't know how easy it will be, for example, to keep
>> CC Mode's indentation styles working in the new mode.
>> 
>> I can't honestly see myself as able to integrate tree-sitter into CC
>> Mode in the short time before the planned pre-test of Emacs 29.  I think
>> we should take up the offer made by João Paulo Labegalini de Carvalho
>> <jaopaulolc@gmail.com> on 2020-10-11 to work on C Mode and possibly C++
>> Mode.
>> 
>> I'm afraid I've only read a small part of this thread on emacs-devel, so
>> there's likely quite a bit of relevant stuff I've missed.
> 
> Could someone please tell me how well tree-sitter supports pre-standard
> C with liberal (and sometimes non-standard) use of the C language?  I'm
> talking about code that looks like this:
> 
> MACRO_USED_TO_DEFINE_SPECIAL_FUNCTIONS (function_name, cells, transform)
>     some_kind_of_ptr cells;
>     another_kind_of_ptr *transform;
> {
>  extern maybe_tls (int) errno;
>  extern caddr_t bar (_P (another_kind_of_ptr, ...));
>  int rc;
> 
>  BEGIN_A_KIND_OF_SECTION ({
>      ENTRY (dx, dy, shx, shy)
> 	float dx, dy, shx, shy;
> 
>      if (!bar (other_function (dx, dy, shx, shy),
> 		etc, etc, etc))
> 	die ("bar", sys_errlist[errno]);
>    }, register float, section_name);
> 
>  rc = more_code_here (&section_name_desc, etc);
>  return rc;
> }
> 
> I don't doubt that tree-sitter is good at parsing newer languages like
> Typescript, but does it support C all that well?

A quick side-by-side comparison of a primitive tree-sitter font-lock I wrote vs c-mode:

Tree-sitter:



C-mode:


Yuan


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