What metaphors are used in Sweeney Todd: The Demon Barber of Fleet Street by Hugh Wheeler?

Cannibalism is taken to its literal and metaphorical meaning in Burton's Sweeney Todd: The Demon Barber of Fleet Street. Literally, the customers of Mrs. Lovett’s pie shop are eating their fellow citizensbecause is a metaphor for industrialization raising the price of meat and forcing people into poverty.