Category: Perl 6
Author/Contact Info Brent Dax (brentdax@cpan.org)
Description: This one is straight out of the documentation included with Parrot's regex library. I'm copying-and-pasting it here only because I wrote the library and the docs. :^) If you're curious to see how this is constructed, take a look at the documentation in the Parrot distribution's rx.ops file. 
    # NOTE: This looks a LOT scarier than it really is
    # "zzabbBBBBBBcdcdcdzz" =~ /ab*[cd]+/i
        rx_allocinfo P0, "zzabbBBBBBBcdcdcdzz"
        bsr RX_0
        rx_info_successful P0, I0
        rx_freeinfo P0
        if I0, $match
        print "no "
    $match:
        print "match"
        end

    RX_0:
        rx_setprops P0, "i", 2
        branch $start0
    $advance:
        rx_advance P0, $fail
    $start0:
        rx_literal P0, "a", $advance

    $start1:
        rx_pushmark P0
    $top1:
        rx_literal P0, "b", $start2
        rx_pushindex P0
        branch $top1
    $back1:
        rx_popindex P0, $advance

    $start2:
        rx_literal P0, "cd", $back1
    $top2:
        rx_oneof P0, "cd", $succeed
        branch $top2

    $succeed:
        rx_succeed P0
        ret
    $fail:
        rx_fail P0
        ret

Back to Code Catacombs