Ties between mined structural patterns in program and their identifier names

Identifier names in readable and maintainable source codes are always descriptive. These names are given based on the implicit knowledge of experienced programmers. In this paper, we propose a structural pattern mining method based on support vector machines (SVM) for source codes. We extract 1,000 method names in object-oriented source codes collected from online software repositories and create 1,000 datasets labeled by positive and negative class. The structural features used for the input feature vectors to the SVM learning are designed for representing partial characteristics in the abstract syntax tree (AST) parsed from a source code. Applying this method, we made an F1 score list of the 1,000 method names, which shows the degree of patterning of each name, by using our structural features. From the list, we confirmed structural patterns were strongly associated with specific method names. A qualitative evaluation of method names was also conducted by mapping the structural feature vector of each program example to the two-dimensional plane in the same way as a previous major study. From the evaluation, we confirmed that the contrasting structure among the programs corresponds to the names given to programs. Furthermore, we show examples of visualization of structural patterns using structural features extracted by feature selection.