public InterpreterRuleContext getRootContext() {
		return rootContext;
	}
Return the root of the parse, which can be useful if the parser
 bails out. You still can access the top node. Note that,
 because of the way left recursive rules add children, it's possible
 that the root will not have any children if the start rule immediately
 called and left recursive rule that fails.

@since 4.5.1
runtime/Java/src/org/antlr/v4/runtime/ParserInterpreter.java