Re: Regular expression functions (Was: Re: [xsl] comments on December F&O draft)

Quoting David Carlisle <davidc@nag.co.uk>:
[...]
> Looking at why one needs regexp in an XML query language, it is usually
> to infer structure into otherwise unstructured (by XML) input.

In general regular expressions are not sufficiently powerful for this,
being one level too low in the Chomsky hierarchy.

I'm not saying that regular expressions arn't useful in many cases, 
merely that they are not sufficiently powerful to describe how to 
transform (i.e. parse) a piece of text into a tree.

[...]