public RuleFunction rule(Rule r) {
		RuleFunction rf = delegate.rule(r);
		for (CodeGeneratorExtension ext : extensions) rf = ext.rule(rf);
		return rf;
	}
Create RuleFunction per rule and update sempreds,actions of parser
 output object with stuff found in r.
tool/src/org/antlr/v4/codegen/OutputModelController.java