private final boolean expect (String source, ParsePosition pos, char ch)
private boolean expect(String source, ParsePosition pos, char ch)
  private final boolean expect (String source, ParsePosition pos, char ch)  {    int x = pos.getIndex();    boolean r = x < source.length() && source.charAt(x) == ch;    if (r)      pos.setIndex(x + 1);    else      pos.setErrorIndex(x);    return r;  }