Mining object-oriented design models for detecting identical design structures

The object-oriented design is the most popular design methodology of the last twenty-five years. Several design patterns and principles are defined to improve the design quality of object-oriented software systems. In addition, designers can use unique design motifs which are particular for the specific application domain. Another common habit is cloning and modifying some parts of the software while creating new modules. Therefore, object-oriented programs can include many identical design structures. This work proposes a sub-graph mining based approach to detect identical design structures in object-oriented systems. By identifying and analyzing these structures, we can obtain useful information about the design, such as commonly-used design patterns, most frequent design defects, domain-specific patterns, and design clones, which may help developers to improve their knowledge about the software architecture. Furthermore, problematic parts of frequent identical design structures are the appropriate refactoring opportunities because they affect multiple areas of the architecture. Experiments with several open-source projects show that we can successfully find many identical design structures in each project. We observe that usually most of the identical structures are an implementation of common design patterns; however we also detect various anti-patterns, domain-specific patterns, and design-level clones.