Clone Detection and Removal for Erlang/OTP within a Refactoring Environment

A well-known bad code smell in refactoring and software maintenance is duplicated code, or code clones. A code clone is a code fragment that is identical or similar to another. Unjustified code clones increase code size, make maintenance and comprehension more difficult, and also indicate design problems such as lack of encapsulation or abstraction. This paper proposes a token and AST based hybrid approach to automatically detecting code clones in Erlang/OTP programs, underlying a collection of refactorings to support user-controlled automatic clone removal, and examines their application in substantial case studies. Both the clone detector and the refactorings are integrated within Wrangler, the refactoring tool developed at Kent for Erlang/OTP.