In many variability-intensive systems, variability is implemented in code units provided by a host language, such as classes or functions, which do not align well with the domain features. Annotating or creating an orthogonal decomposition of code in terms of features implies extra effort, as well as massive and cumbersome refactoring activities. In this paper, we introduce an approach for identifying and visualizing the variability implementation places within the main decomposition structure of object-oriented code assets in a single variability-rich system. First, we propose to use symmetry, as a common property of some main implementation techniques, such as inheritance or overloading, to identify uniformly these places. We study symmetry in different constructs (e.g., classes), techniques (e.g., subtyping, overloading) and design patterns (e.g., strategy, factory), and we also show how we can use such symmetries to find variation points with variants. We then report on the implementation and application of a toolchain, symfinder, which automatically identifies and visualizes places with symmetry. The publicly available application to several large open-source systems shows that symfinder can help in characterizing code bases that are variability-rich or not, as well as in discerning zones of interest w.r.t. variability. CCS CONCEPTS• Software and its engineering → Software product lines; Object oriented development; Reusability. KEYWORDSIdentifying software variability, visualizing software variability, object-oriented variability-rich systems, tool support for understanding software variability, software product line engineering

In Software Product Line (SPL) engineering, mapping domain features to existing code assets is essential for variability management. When variability is already implemented through Object-Oriented (OO) techniques, it is too costly and error-prone to refactor assets in terms of features or to use feature annotations. In this work, we delve into the possible usage of automatically identified variation points with variants in an OO code base to enable feature mapping from the domain level. We report on an experiment conducted over ArgoUML-SPL, using its code as input for automatic detection through the symfinder toolchain, and the previously devised domain features as a ground truth. We analyse the relevance of the identified variation points with variants w.r.t. domain features, adapting precision and recall measures. This shows that the approach is feasible, that an automatic mapping can be envisaged, and also that the symfinder visualization is adapted to this process with some slight additions. CCS CONCEPTS • Software and its engineering → Software product lines.

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