my $re1 = qr{([0-4])};
my $re2 = qr{([5-9])};

my %hash = ("$$re1" => "foo", "$$re2" => "bar");

$_ = "-5-";
for my $re (keys %hash) {
    print "match: ($1) $hash{$re}\n" if /$re/;
}

# outputs:
# match: (5) bar