static S ai_patternSwitch(S from, S to, S s) {
  L<S> tok = javaTokPlusBracketsC_unquote(s);
  L<S> tok1 = javaTokC(from), tok2 = javaTokC(to);
  S op = getOperator(s);
  if (neq(from, op))
    fail("Different operator: " + renderStructs(+from, +to, +op, +s));
    
  L<S> operands = ai_operands(from, s);
  int iOperand = 0;
  new L<S> out;
  
  for i over tok2: {
    S t = tok1.get(i);
    if (eq(get(i), "*"))
      out.add(operands.get(iOperand++));
    else
      out.add(t);
  }
  ret joinWithSpace(out);
}