On 19 Dec 2011, at 4:50 PM, Nick Fitzsimons wrote: > Strictly speaking that regex cannot determine that an email address is > well-formed per the RFC as the grammar defining the form of email addresses > is a Type 2 Chomsky Grammar and regular expressions are limited to Type 3 > Chomsky Grammars.
That's true of the whole address line, but is it true of what people usually want to validate in an email-address field (the "addr-spec" production from rfc2822, without any comments)? I think that language is regular, unless there's a recursive rule hidden in the obsolete forms part of the grammar. The comment syntax is type-2, of course, because it requires balanced parentheses. (And of course, regexes aren't even regular expressions aka type-3 grammars any more--- but not enough more to parse balanced strings, I think.) -- You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com. To unsubscribe from this group, send email to django-developers+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-developers?hl=en.
