!7

abstract sclass Proposal {
  int localScore() { ret 0; }
  toString { ret "[" + localScore() + "] " + sfu(this); }
  Proposal parent;
  
  selfType parent(Proposal parent) { this.parent = parent; this; }
}

static noToString record EnclosedIn(S l, LS contents, S r) extends Proposal {
  int localScore() { ret scoreOneIfBracketPair(l, r); }
}

static noToString record Infix(LS l, S op, LS r) extends Proposal {}

svoid parse(LS tok, Proposal parent) {
  // drop first and last
  if (l(tok) >= 3)
    emit(new EnclosedIn(first(tok), dropFirstAndLast2(tok), last(tok)).parent(parent));
  for (int i = 1; i < l(tok)-1; i++)
    emit(new Infix(subList(tok, 0, i), tok.get(i), subList(tok, i+1)).parent(parent));
}

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