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   Re: [xml-dev] Validate an XPath with regex

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Hi Niels,

I'm not a linguistics expert but I think that regular expressions and 
XPath expressions come at different levels of the Chomsky hierarchy [1] 
- regular expressions would be type 3, Regular, but XPath would be type 
2, Context Free. One notable difference is that you can't specify 
balanced syntax with type 3 grammars, so you couldn't specify anything 
requiring correctly nested square or round brackets for instance.

Hope this helps -


[1] http://www.wikipedia.com/wiki/Chomsky_hierarchy

Niels Peter Strandberg wrote:

> Shouldn't it be possible to validate the syntax of an XPath string 
> using regular expressions. Im not a regex expert, so just want to ask 
> you out there if it could be done.


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