The true power of regular expressions (2012)
Summary
The article argues that regular expressions, especially PCRE-based implementations, are far more powerful than the traditional view that they only handle simple patterns. It covers the relationship between regexes and formal grammars, shows how regexes can match context-free languages (and some context-sensitive languages) using advanced constructs, and discusses practical cautions like parsing HTML. It also demonstrates how features like backreferences increase expressive power and introduces the concept of DEFINE-based grammar mappings within regexes.