

Is there a regular expression to detect a valid regular expression? - joshbaptiste
http://stackoverflow.com/questions/172303/is-there-a-regular-expression-to-detect-a-valid-regular-expression

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andrewaylett
See, this is one thing that annoys me about so-called 'regular' expression
engines: they're not actually very regular any more. I understand that they
can be useful (indeed, very useful sometimes) but I think that having a
'regular expression' that actually matches a context-free grammar is more than
a bit confusing.

