Re: [Json] ABNF nits

[Stefan Drees <[e-mail]>]

On 2013-06-07 05:15, James H. Manger wrote:
>>>> Some things I found futzing with the ABNF:
>>>>
>>>> - normalize the indentation (makes it easier to pull out)
>>>> - Hex literals need to be uppercase.  The false and null rules are
>>>> wrong.
>>>
>>> Lowercase is allowed in hex literals.
>>> It links back to HEXDIG in RFC5234 (or RFC 4234).
>>> You have to remember the sneaky ABNF rule that quoted strings (eg "A")
>>> are case insensitive. "A" is equivalent to %x41 / %x61.
>>
>> Crap.  I didn't see that because it's in a "Note:" in section 2.3.
>
> I didn't call it "sneaky" for nothing ;) ...

lucky JSON, it only needs short tokens (cowardly avoiding the word 
single character here ;-)

If defining a grammar with real case-sensitive "word"-ish tokens in it, 
ABNF is IMO barely usable, unless you extend it with say single quotes 
as case-sensitve string delimiters. But then dealing with two kinds of 
strings also has it's catches =(


>> Regardless, we should change  both of those rules for consistency with
>> the rest of the doc.
>>
>>>> - DIGIT and HEXDIG are neither defined nor imported, as far as I can
>>>> tell.
>>>>  I suggest:
>>>>
>>>> DIGIT = %x30-39                        ; 0-9
>>>> HEXDIG = %x30-39 / %x41-46 / %x61-66   ; 0-9, A-F, or a-f
>>
>> I still recommend being explicit about this, like the rule for e.
>
> I agree.
> Add DIGIT and HEXDIG to the doc so all the ABNF is present.
> Use your definition of HEXDIG above, not the RFC5234 one, to avoid the sneaky ABNF rule.
> Optionally add a note "; DIGIT and HEXDIG are equivalent to rules with the same names in [RFC5234]".

+1 on your proposal James (including the ABNF comment).

Stefan.