static class Symbol implements CharSequence, Comparable<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(lowerCase()); }
  toString { ret text; }
  S lowerCase() { ret master.lowerCase; }
  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;
  }
  
  public int length() { ret text.length(); }
  public char charAt(int index) { ret text.charAt(index); }
  public CharSequence subSequence(int start, int end) {
    ret text.substring(start, end);
  }
  
  // This really has to be correct for TreeMap<Symbol, ...>
  // equals() <=> compareTo() == 0 or at least
  // equals() => compareTo() == 0.
  public int compareTo(Symbol s) {
    ret lowerCase().compareTo(s.lowerCase());
  }
}

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