[x3d-public] X3D regular expression (regex) improvements

[Leonard Daly]

Just a single note and a question.

[most of message stripped away...]


> It is great when we find those patterns, am trying to keep things 
> maintainable.  The color-coding on web page definitely helps.
>
> Negative lookahead is good for avoiding illegal values, but not 
> allowed in XML Schema (probably to avoid computational denial of 
> service attacks_.  Have listed a pattern nevertheless, other 
> languages/tools might want to use it.
>
> ==================
> Disallowed values:
>
> * Negative lookahead filters can disqualify attributes that contain 
> illegal values.
> * W3C Recommendation for XML Schema (XSD) unfortunately does not 
> support this construct.
> * (?!((0|0.0*|.0+)\s+){3}) prohibits 0 0 0 since zero vector is 
> illegal as initial axis triplet of an SFRotation.

As I read the above

If not
   (0 or 0.0* or .0+
    repeated white-space character
   ) three times

You should escape the "dot"s; otherwise, it accepts any character (the 
dots are meta-character when not in a character class)

This would be:

    (?!((0|0\.0*|\.0+)\s+){3})


See https://regex101.com/ to test and explain the regex.


Is there any consideration for internationalization of number display. 
Most of Europe uses "," (comma) as the radix character (decimal 
separator). [See 
https://docs.oracle.com/cd/E19455-01/806-0169/overview-9/index.html]



-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Past Chair
President, Daly Realism - /Creating the Future/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://web3d.org/pipermail/x3d-public_web3d.org/attachments/20180817/497ca72c/attachment.html>