Parser Generator

There are two ways to write a parser: a hand-written recursive descent parser or one generated by a parser generator such as ANTLR4 or YACC/Bison. The former is flexible but more prone to errors and harder to maintain, while the latter offers better maintainability but requires in-depth knowledge of parser generation. Felys originally used a hand-written parser but later migrated to a customized parser generator that also bootstraps itself. This section will discuss how to build a PEG parser generator along with a lexer generator.