Using Deep Learning to Automatically Improve Code Readability

Reading source code occupies most of developer's daily activities. Any maintenance and evolution task requires developers to read and understand the code they are going to modify. For this reason, previous research focused on the definition of techniques to automatically assess the readability of a given snippet. However, when many unreadable code sections are detected, developers might be required to manually modify them all to improve their readability. While existing approaches aim at solving specific readability-related issues, such as improving variable names or fixing styling issues, there is still no approach to automatically suggest which actions should be taken to improve code readability. In this paper, we define the first holistic readability-improving approach. As a first contribution, we introduce a methodology for automatically identifying readability-improving commits, and we use it to build a large dataset of 122k commits by mining the whole revision history of all the projects hosted on GitHub between 2015 and 2022. We show that such a methodology has 86% accuracy. As a second contribution, we train and test the T5 model to emulate what developers did to improve readability. We show that our model achieves a perfect prediction accuracy between 21% and 28%. The results of a manual evaluation we performed on 500 predictions shows that when the model does not change the behavior of the input and it applies changes (34% of the cases), in the large majority of the cases (79.4%) it allows to improve code readability.