a clone of the parser generator Bison (thus Yacc,) but in JavaScript. It includes its own lexical analyzer modeled after Flex.

compiles executable finite state machines from regular languages. Ragel targets C, C++, Objective-C, D, Java and Ruby. Ragel state machines can not only recognize byte sequences as regular expression machines do, but can also execute code at arbitrary points in the recognition of a regular language. Code embedding is done using inline operators that do not disrupt the regular language syntax. Ragel provides a very flexible interface to the host language that attempts to place minimal restrictions on how the generated code is integrated into the application. The generated code has no dependencies.