static class Symbol {
  S text;
  MasterSymbol master;
  
  *() {}
  *(S *text, bool dummy) {} // weird signature to prevent accidental calling
  *(S *text, MasterSymbol *master) {}
  
  bool isMaster() { ret master == this; }
  public int hashCode() { ret main.hashCode(master.lowerCase); }
  toString { ret text; }
  public bool equals(O o) {
    if (!(o instanceof Symbol)) false;
    bool result = o instanceof Symbol && master == o/Symbol.master;
    ifdef symbol_debug
      print("Symbol.equals: " + this + " vs " + o + " => " + result);
    endifdef
    ret result;
  }
}

static class MasterSymbol extends Symbol {
  S lowerCase;
  
  *() {}
  *(S *text, bool dummy) { master = this; lowerCase = lower(text); }
}