public CodeBlockForAlt alternative(Alternative alt, boolean outerMost) {
		CodeBlockForAlt blk = delegate.alternative(alt, outerMost);
		if ( outerMost ) {
			currentOuterMostAlternativeBlock = (CodeBlockForOuterMostAlt)blk;
		}
		for (CodeGeneratorExtension ext : extensions) blk = ext.alternative(blk, outerMost);
		return blk;
	}
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