Clone Detection in a Product Line Context

Software Product Lines (SPL) can be used to create and maintain different variants of software-intensive systems by explicitly managing variability. Often, SPLs are organized as an SPL core, common to all products, upon which product-specific components are built. Following the so called grow-and-prune model, SPLs may be evolved by copy&paste at large scale. New products are created from existing ones and existing products are enhanced with functionalities specific to other products by copying and pasting code between product-specific code. To regain control of this unmanaged growth, such code may be pruned, that is, identified and refactored into core components upon success. Clone detection offers effective means to identify duplicated source code. However, variablity in product lines, especially when targeting embedded devices, is often implemented using a preprocessor. This limits the applicable clone detection techniques to ones with lower precision. We describe how information about function locations can be used to improve the results of these token-based clone detectors.