Re: [GSOC][PATCH] userdiff: add support for Scheme

[Atharva Raykar <raykar.ath@gmail.com>]

On 28-Mar-2021, at 04:39, Junio C Hamano <gitster@pobox.com> wrote:
> 
> Junio C Hamano <gitster@pobox.com> writes:
> 
>> Atharva Raykar <raykar.ath@gmail.com> writes:
>> ...
>>> +           (ChangeMe 'suite-name tests)))))))
>>> \ No newline at end of file
>> 
>> Is there a good reason to leave the final line incomplete?  ...
>> I am also trying to figure out what you wanted to achieve ...
> 
> Taking all of them together, here is what I hope you may agree as
> its improved version.  The only differences from what you posted are
> corrections to all the "\ No newline at end of file" and the simplification
> of the pattern (remove "a dot" from the alternative and add \t next
> to SP).  Without changes, the new tests still pass so ... ;-)
> 
>    diff --git c/userdiff.c w/userdiff.c
>    index 5fd0eb31ec..685fe712aa 100644
>    --- c/userdiff.c
>    +++ w/userdiff.c
>    @@ -193,12 +193,8 @@ PATTERNS("rust",
>             "|[-+*\\/<>%&^|=!:]=|<<=?|>>=?|&&|\\|\\||->|=>|\\.{2}=|\\.{3}|::"),
>     PATTERNS("scheme",
>             "^[\t ]*(\\(define-?.*)$",
>    -	 /*
>    -	  * Scheme allows symbol names to have any character,
>    -	  * as long as it is not a form of a parenthesis.
>    -	  * The spaces must be escaped.
>    -	  */
>    -	 "(\\.|[^][)(\\}\\{ ])+"),
>    +	 /* whitespace separated tokens, but parentheses also can delimit words */
>    +	 "([^][)(\\}\\{ \t])+"),
>     PATTERNS("bibtex", "(@[a-zA-Z]{1,}[ \t]*\\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
>             "[={}\"]|[^={}\" \t]+"),
>     PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",

Thanks for these. I will eventually send another patch with the whitespaces corrected,
and try to see if there is a better way to handle backslashes, other than the regex I
suggested. I will also be writing another test case to check that case properly.

I will also incorporate the other changes suggested by Johannes and Ævar as well,
My regex was not supposed to capture forms like `defined-thing`. And there are a
few rough edges with some of my test cases, which I will correct as well in the next
patch. It is also worth spending some more time and see if there is any other form other
than definitions that a Scheme programmer other than myself may be interested in. I will
consult a few Scheme communities and mailing lists and see what more experienced
programmers have to say.