use strict; 
use warnings; 
use 5.012;

use Parse::RecDescent;

$::RD_ERRORS = 1; #Parser dies when it encounters an error
$::RD_WARN   = 1; #Enable warnings - warn on unused rules &c.
$::RD_HINT   = 1; #Give out hints to help fix problems.
#$::RD_TRACE  = 1; #Trace parsers' behaviour

my $text = <<'END_OF_TEXT';
{{ hello }}
END_OF_TEXT

my $grammar = <<'END_OF_GRAMMAR';
    {
        use 5.012;
        use Data::Dumper;
    }

    startrule: lbrace(2) 
               'hello' 
               rbrace(2) 

    lbrace: / [{] /xms
    rbrace: / [}] /xms
                  
END_OF_GRAMMAR

my $parser = Parse::RecDescent->new($grammar) 
    or die "Bad grammar!\n";

defined $parser->startrule($text) 
    or die "Can't match text";