!7

abstract sclass Proposal { toString { ret sfu(this); } }
static noToString record TwoSplit(LS a, LS b) extends Proposal {}
static noToString record ThreeSplit(LS a, LS b, LS c) extends Proposal {}

svoid parse(LS tok) {
  // drop first and last
  if (l(tok) >= 3)
    emit(new ThreeSplit(ll(first(tok)), dropFirstAndLast_noNewList(tok), ll(last(tok))));
  for (int i = 1; i < l(tok)-1; i++)
    emit(new TwoSplit(subList(tok, 0, i), subList(tok, i)));
}

p-exp {
  LS tok = javaTokC("[(a|b), (c|d), (e|f)]");
  parse(tok);
}