This is the base class for gathering detailed information about prediction events which occur during parsing. Note that we could record the parser call stack at the time this event occurred but in the presence of left recursive rules, the stack is kind of meaningless. It's better to look at the individual configurations for their individual stacks. Of course that is a PredictionContext object not a parse tree node and so it does not have information about the extent (start...stop) of the various subtrees. Examining the stack tops of all configurations provide the return states for the rule invocations. From there you can get the enclosing rule.