set flag SymbolWithMasterSymbol.

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; }

  final public int hashCode() { ret master.lowerCaseHash; }

  S text() { ret text; }

  final toString { ret text; }

  S lowerCase() { ret lower(text()); }

  final 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());

    ret lowerCaseCompare(text, s.text);

  }

}

static final class MasterSymbol extends Symbol {

  //S lowerCase;

  int lowerCaseHash;

  bool dollarVar;

  *() {}

  *(S *text, bool dummy) {

    master = this;

    S lowerCase = lower(text);

    lowerCaseHash = lowerCase.hashCode();

    dollarVar = isDollarVar(lowerCase);

  }

  int lowerCaseHash() { ret lowerCaseHash; }

}