  @GwtIncompatible // regular expressions
  private static Pattern fpPattern() {
    String decimal = "(?:\\d++(?:\\.\\d*+)?|\\.\\d++)";
    String completeDec = decimal + "(?:[eE][+-]?\\d++)?[fFdD]?";
    String hex = "(?:\\p{XDigit}++(?:\\.\\p{XDigit}*+)?|\\.\\p{XDigit}++)";
    String completeHex = "0[xX]" + hex + "[pP][+-]?\\d++[fFdD]?";
    String fpPattern = "[+-]?(?:NaN|Infinity|" + completeDec + "|" + completeHex + ")";
    return Pattern.compile(fpPattern);
  }