Scanner, lexer, parser for ruby's regular expressions

 A library for tokenizing, lexing, and parsing Ruby regular expressions.
 .
  * Multilayered
    * A scanner/tokenizer based on Ragel
    * A lexer that produces a "stream" of token objects.
    * A parser that produces a "tree" of Expression objects (OO API)
  * Runs on Ruby 1.9, 2.x, and JRuby (1.9 mode) runtimes.
  * Recognizes Ruby 1.8, 1.9, and 2.x regular expressions