The {@link Recognizer} where this exception originated.
Get the ATN state number the parser was in at the time the error occurred. For {@link NoViableAltException} and {@link LexerNoViableAltException} exceptions, this is the {@link DecisionState} number. For others, it is the state whose outgoing edge we couldn't match.
Gets the set of input symbols which could potentially follow the previously matched symbol at the time this exception was thrown.
Gets the {@link RuleContext} at the time this exception was thrown.
Gets the {@link Recognizer} where this exception occurred.
TODO add class description