Refactoring delta-oriented product lines to enforce guidelines for efficient type-checking

A Software Product Line (SPL) is a family of similar programs generated from a common code base. Delta-Oriented Programming (DOP) is a flexible and modular approach to construct SPLs. Ensuring type safety in an SPL (i.e., ensuring that all its programs are well-typed) is a computationally expensive task. Recently, five guidelines to address the complexity of type checking delta-oriented SPLs have been proposed. This paper presents algorithms to refactor delta-oriented SPLs in order to follow the five guidelines. Complexity and correctness of the refactoring algorithms are stated.