nl_tokens: a State is a rule at a position from a given starting point in the input stream ( reference )
pl_tokens: function State ( rule , dot , reference , wantedBy ) { this . rule = rule ; this . dot = dot ; this . reference = <mask> ; this . data = [ ] ; this . wantedBy = wantedBy ; this . isComplete = this . dot === rule . symbols . length ; }