Re: [PATCH] userdiff: add Julia to supported userdiff languages

From: Johannes Sixt <j6t@kdbg.org>
Date: Jan 10, 2020, 20:14 UTC
Message-ID: <cf486cb7-0ea5-92e8-1454-5059ea009ddf@kdbg.org>
In-Reply-To: <YqXJB_En1hjDpzUmawtrEYBztOGh_1uSmwxsQyQ646RtwGnYppq-xg26rwM0x5pu6E8PMVq22HwfSSFXN9aaD9BowSUH1YfztHRUomhOe6E=@rtzoeller.com>

Am 10.01.20 um 19:15 schrieb Ryan Zoeller:

Show 16 quoted lines

> On Friday, January 10, 2020 11:43 AM, Johannes Sixt <j6t@kdbg.org> wrote:
>> Am 10.01.20 um 04:10 schrieb Ryan Zoeller via GitGitGadget:
>>> -   /* Real and complex literals */
>>> -   "|[-+0-9.e_(im)]+"
>>
>> I am curious: is '(1+2i)' a single literal -- including the parentheses?
>> The expression would also mistake the character sequence '-1)+(2+' as a
>> single word; is it intended?
> 
> This part of the regular expression has a pretty major mistake due
> to me misunderstanding how the parentheses were being interpreted.
> It should be something along the lines of `([-+0-9.e_]|im)+`.
> 
> Julia uses `im` as the designation for an imaginary value; this regex
> was intended to admit e.g. 1+2im, in addition other numeric values
> such as 1_000_000 and 1e10.

I see. I suggest to treat 1+2im as three words '1', '+', and '2im', and to model numbers in this way:

	|[0-9][0-9_.]*(e[-+]?[0-9_]*)?(im)?

In particular, require a digit at the begin, and do not allow '-' and '+' an arbitrary number of times, because it would catch 1+2+3+4 as a single word.

-- Hannes