gistfile1.perl

use 5.010;
use strict;
use warnings;

my $rec = rec();
$rec->alternative( 'XX', undef, 2 );
while (1) {
    say $rec->earleme_complete;
    say $rec->exhausted? "exhausted" : "please continue";
}

sub rec {
    use Marpa::XS;

    my $grammar = Marpa::XS::Grammar->new( {
        actions => 'main',
        default_action => 'do_what_I_mean',
        start   => 'query',
        rules   => [
            [ query => [qw(XX)] ],
        ],
        lhs_terminals => 0,
    });
    $grammar->precompute;
    return Marpa::XS::Recognizer->new( { grammar => $grammar } );
}