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Re^4: Regexp not capturing in named subrules

by diotalevi (Canon)
on Sep 16, 2009 at 17:25 UTC ( #795673=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Regexp not capturing in named subrules
in thread Regexp not capturing in named subrules

No, you misread. \g<thing> in Ruby-1.9's oniguruma works like (?&thing) in perl 5.10. It's a subroutine call. The grammar section (?: ... ){0} creates the subroutines and I just call an entry point later.

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Re^5: Regexp not capturing in named subrules
by merlyn (Sage) on Sep 16, 2009 at 18:29 UTC
    The grammar section (?: ... ){0} creates the subroutines...
    I'm really confused. Did you invent that construct yourself (which looks broken to me) or is it something special-cased in recent grammars (away from its pointless purpose) and recommended in some document I haven't read yet?

    Because if I was writing a regex engine, I'd actually turn {0} into a fatal error, with the invoker needing a clue-bat.

    -- Randal L. Schwartz, Perl hacker

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

      I read the idea (?<name>...){0} in the Oniguruma documentation but it was applicable to Perl too. In Perl-5.10 implementation, (?:...){0} leaves active elements like regexp routines handy in the regexp. Really, that seems to work just fine. Anyway, it's pretty clear I'm likely doing something Yves never intended when he added (?&name) support.

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        I think the way God Intended patterns to be defined for later use is

        qr/(?(DEFINE) (?<name>pattern) )/x

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