[x3d-public] SFImage regex

[Andreas Plesch]

> Date: Mon, 11 Jun 2018 11:03:13 -0700
> From: Leonard Daly <Leonard.Daly at realism.com>
> To: x3d-public at web3d.org
> Subject: Re: [x3d-public] SFImage regex
> Message-ID: <bbff6404-96fc-fc91-b9a7-6ba57d98b7e3 at realism.com>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Andreas,
>
> There is an error in the regex:
> >
> > Tangentially, repeated ranges also look not so nice but are apparently
> > common: [0-9a-fA-F]
> > [0-9]|[a-f|[A-F] reads better to me and that is why I preferred that.
>
> There should be a ']' after 'f'. Personally, I prefer the first form
>

well spotted !


> [0-9a-fA-f] or even [a-fA-F\d]. If the entire string is case insensitive
> then use the language-specific 'i' mode or surround the entire string as
> in (?i)...[a-f\d]...(?-i) or shorter (?i)...[a-f\d]...
>

The more familiar regex becomes, more concise variations may read better. i
mode may not be supported by XML.


> I prefer grouping all of the ranges together so that repeated
> vertical-ness is not present as it would be with ']|['. It also makes it
> clearer that the range of characters is all one unit.
>

It does. Still, [a-fA-F0-9] may look a bit confusing to the casual regex
users since there is a natural tendency to first join letters, then
consider punctuation or signs.

In the end, it is just a personal preference,

-Andreas


> --
> *Leonard Daly*
> 3D Systems & Cloud Consultant
> LA ACM SIGGRAPH Past Chair
> President, Daly Realism - /Creating the Future/
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-- 
Andreas Plesch
Waltham, MA 02453
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