Re: [Issue-67] [Action-385] Work on regex for validating regex subset proposal

On 8.4.2013 18:48, Felix Sasaki wrote:

>> I'm not sure whether this ABNF does what it should do. For example this
>> grammar allows ^ almost anywhere but I think that in most RE engines ^
>> should directly follow [ if it's meant as a negation.
> 
> Agree - you could resolve that by removing neg from
> char = [neg] BMP+escapes
> and change
> allowedCharacters = start 1*range end ["+"]
> to
> allowedCharacters = start [neg] 1*range end ["+"]

Yes, this resolves this one particular issue. I haven't been tracking RE
discussion that closely, but I'm not sure whether it's clear what should
be supported. My recollection that what people asking for change wanted
was something like:

[11]    charClass (http://www.w3.org/TR/xmlschema-2/#nt-charClass)

just without allowing following productions:  MultiCharEsc, catEsc  and
complEsc.

This is very different from what your simple ABNF allows. Might be
implementers know what subset of REs should be supported but this has to
be explicitly written down somewhere in the spec if we want to reach
interoperability.

    Jirka

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