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Date: Fri, 1 Nov 2013 10:57:35 -0700
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From: Martin Thomson <martin.thomson@gmail.com>
To: Bjoern Hoehrmann <derhoermi@gmx.net>
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Subject: Re: [abnf-discuss] addIceCandidate behavior
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On 1 November 2013 10:39, Bjoern Hoehrmann <derhoermi@gmx.net> wrote:
> * Martin Thomson wrote:
>>On 31 October 2013 22:37, Harald Alvestrand <harald@alvestrand.no> wrote:
>>> Perhaps the description (and the throw) is better applied to
>>> RTCIceCandidate's constructor, so that an RTCIceCandidate is always known to
>>> be syntactically valid?
>>
>>I'm happy to generate a regex for folks if they are concerned about
>>implementing a validity check in the constructor.
>>
>>See: https://github.com/martinthomson/abnf2regex
>
> Does the tool support regular grammars with left- and right-recursive
> rules?

That is where it breaks.  Not all regular expression languages support
the easy solution (backreferences to named captures), and I haven't
spent the time to work out how to express left- and right- recursive
rules the non-easy way.

That said, it is sufficient to express email, URI, and SDP grammars.
The only other grammar I tried was NAI, but that's perverse, and
doesn't have a fixed idea of what an atom is.
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