protected void enterRule(ParseTreeListener listener, RuleNode r) {
		ParserRuleContext ctx = (ParserRuleContext)r.getRuleContext();
		listener.enterEveryRule(ctx);
		ctx.enterRule(listener);
    }
Enters a grammar rule by first triggering the generic event {@link ParseTreeListener#enterEveryRule}
then by triggering the event specific to the given parse tree node
@param listener The listener responding to the trigger events
@param r The grammar rule containing the rule context
runtime/Java/src/org/antlr/v4/runtime/tree/ParseTreeWalker.java