Unification and refactoring of clones

Code duplication has been recognized as a potentially serious problem having a negative impact on the maintain-ability, comprehensibility, and evolution of software systems. In the past, several techniques have been developed for the detection and management of software clones. Existing code duplication can be eliminated by extracting the common functionality into a single module. However, the unification and refactoring of software clones is a challenging problem, since clones usually go through several modifications after their initial introduction. In this paper we present an approach for the unification and refactoring of software clones that overcomes the limitations of previous approaches. More specifically, our approach is able to detect and parameterize non-trivial differences between the clones. Moreover, it can find an optimal mapping between the statements of the clones that minimizes the number of differences. We compared the proposed technique with a competitive clone refactoring tool and concluded that our approach is able to find a significantly larger number of refactorable clones.