Abstract:
Understanding the nature of regular expression (regex) issues is important to tackle practical issues developers face in regular expression usage. Knowledge about the nature and frequency of various types of regular expression issues, such as those related to performance, API misuse, and code smells, can guide testing, inform documentation writers, and motivate refactoring efforts. However, beyond ReDoS (Regular expression Denial of Service), little is known about to what extent regular expression issues affect software development and how these issues are addressed in practice.This paper presents a comprehensive empirical study of 350 merged regex-related pull requests from Apache, Mozilla, Facebook, and Google GitHub repositories. Through classifying the root causes and manifestations of those bugs, we show that incorrect regular expression behavior is the dominant root cause of regular expression bugs (165/356, 46.3
