Build Your Own Swift Regex: A Gentle Introduction to Swift Regex

This conference talk from try! Swift Tokyo 2025 explores how to build a custom Swift regex engine from scratch. Dive into the fundamentals of regular expressions by implementing the three core operations: concatenation, alternation, and repetition. Learn about backtracking (VM-based) approaches similar to Swift's official regex engine, which aims to be a comprehensive superset of existing regular expression implementations. Speaker Kishikawa Katsumi guides you through this gentle introduction that serves as a stepping stone toward understanding Swift's more complex official regex engine and potentially contributing to its ongoing development, as some features like lookbehind remain unimplemented. This 20-minute presentation is part of the three-day try! Swift Conference (April 9-11, 2025), where developers worldwide gather to share Swift development tips, tricks, case studies, and collaborate with fellow Swift enthusiasts.