use warnings;
use strict;

sub dive {
	my ($data, @path) = @_;
	die "unsafe keys" if grep { /[^a-zA-Z0-9_]/ } @path;
	return eval '$data->'.join('', map { "{$_}" } @path);
}

use Test::More tests=>6;

sub exception (&) { eval { shift->(); 1 } ? undef : ($@ || die) }

our %quz = ( quz => 'Hello!' );
our %foo = ( bar => 'quz', baz => { hello => "World!" } );

is dive(\%quz, qw/ quz /), 'Hello!';
is dive(\%foo, qw/ bar /), 'quz';
is dive(\%foo, qw/ bar x /), undef;
is dive(\%foo, qw/ baz hello /), 'World!';
is dive(\%foo, qw/ bar quz /), undef;
like exception { dive(\%foo, qw/ $hello /) },
	qr/\bunsafe keys\b/i;