ietf-nntp Wildmats

[Clive D.W. Feather]

Russ Allbery said:
> This section:
> 
>   - Where a wildmat-set-body contains one or more "-"s, they shall be
>     examined from left to right; each shall be the centre of a
>     wildmat-set-1-range or wildmat-set-2-range if the whole wildmat-set-body
>     can be thus parsed.
> 
> implies that there's some backtrack and rescanning needed for some types
> of ranges.

It wasn't meant to. I had about 6 goes at that wording and *still* wasn't
happy with it; if anyone else can do better, please do.

Perhaps I should just recast the grammar to handle this.

> It turns out, unless I missed something when writing an
> implementation, that there actually aren't any.  If you take any
> non-initial "-" to be a range separator as soon as you encounter it and
> consider the character before and after it in that light, unless it's the
> last character of the range, you'll always find a valid parse and there's
> never any need to backtrack.  (You can get ranges where the final
> character is less than the initial character, but that's not a syntax
> error, just an undefined range.)

Completely correct.

> Also, I think we should drop \s to match spaces if we're going to use \u.

I don't have a problem with this, unless we need a "match a sequence of
white space" escape - see other threads.

> And do we really need to rule out all control characters in the wildmat
> grammar?

I don't know. If people tell me we want to allow some, I'll put them in.

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