parseJSON bug

[Tofu Ninja]

On Thursday, 8 August 2013 at 15:45:22 UTC, Nick Sabalausky wrote:
> On Thu, 08 Aug 2013 17:17:38 +0200
> "Tofu Ninja" <emmons0 at purdue.edu> wrote:
>
>> On Thursday, 8 August 2013 at 13:56:15 UTC, Dicebot wrote:
>> > On Thursday, 8 August 2013 at 13:49:22 UTC, bearophile wrote:
>> >> In my opinion we should follow the formal JSON grammar.
>> >
>> > This. Anyone who wants JavaScript behavior can use own 
>> > third-party library bust standard library must behave 
>> > according to published standards and specifications.
>> 
>> A formal grammar can be found here starting on page 202 but I 
>> don't know enough about grammars to be able to interpret it.
>> http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
>> 
>> Im starting to become less sure if its a bug or not...
>
> I think that makes it clear that whitespace is NOT allowed 
> within
> numeric or fractional literals. Note that the JSONNumber and
> JSONFraction tokens are defined in the lexical section 
> (15.12.1.1). In
> a lexer, whitespace is something that is always handled 
> explicitly (as
> they do, in both the JSONWhiteSpace and JSONStringCharacter 
> tokens).
>
> Down in the "Syntactic Grammar" section (15.12.1.2), they don't
> explicitly mention anything about whitespace (for example, in 
> the
> JSONElementList token, where we already *know* whitespace is 
> allowed).
> This is undoubtedly because (aside from lexing) whitespace is 
> generally
> NOT explicit, but rather implied to optionally exist 
> before/after each
> token.
>
> It sounds like the bug is that std.json is currently treating 
> JSONNumber
> (and maybe JSONFraction too) as a parser-handled nonterminal, 
> instead
> of a lexer-handled terminal as the spec indicates.

Just out of curiosity what is this sort of grammar format called 
or what would one want to try to look up to understand it? I just 
have seen it around a few times and never really knew what it was 
about other than some how it describes a language.