System.Text.RegularExpressions.RegexCharClass.CategoryDescription C# (CSharp) Method

        private static String CategoryDescription(char ch) {
            if (ch == SpaceConst)
                return "\\s";
            else if ((short) ch == NotSpaceConst)
                return "\\S";
            else if ((short) ch < 0) {
                return "\\P{" + Categories[(- ((short)ch) - 1)] + "}";
            }
            else {
                return "\\p{" + Categories[(ch - 1)] + "}";
            }
        }