gistfile1.txt

#!/usr/bin/perl

use Regexp::Grammars;
use File::Slurp;
use Data::Dump qw/dump/;

my $config = read_file $ARGV[0];

my $parser = qr{
  <[Item]>+

  <token: Item>
    <Directive> | <[Comment]>+ | <KeyValue>

  <token: Comment>
    \s*\#\s*<MATCH=([^\n]*)>\n

  <rule: Directive>
    \< <Key=(\w+)> \>
    <[Value=Item]>+
    \</ (??{$MATCH{Key}}) \>

  <rule: KeyValue>
    <Key=(\w+)>\s+<Value=(\w+)>
}x;

dump %/ if $config =~ $parser;