This library is about grammars and parsing, and in particular, LR parsers.
Currently, the library has the capability to describe a grammar, and derive the transitions between item sets (parser states) of that grammar. It cannot (yet) build the actual parser. (The transition table needs to be convert to action and goto tables, and an engine capable of using those tables needs to be written.) See the Wikipedia article LR parsers sections on “Constructing LR(0) parsing tables” and “Table construction” — the code is currently at the step “Constructing the action and goto tables”.