enterRule method
Always called by generated parsers upon entry to a rule. Access field {@link #_ctx} get the current context.
Implementation
void enterRule(ParserRuleContext localctx, int state, int ruleIndex) {
this.state = state;
context = localctx;
context!.start = _input.LT(1)!;
if (buildParseTree) addContextToParseTree();
if (_parseListeners != null) triggerEnterRuleEvent();
}