System.Xml.Xsl.Runtime.NumberFormatter.NumberFormatter C# (CSharp) Method

        public NumberFormatter(string formatString, int lang, string letterValue, string groupingSeparator, int groupingSize) {
            Debug.Assert(groupingSeparator.Length <= 1);
            this.formatString       = formatString;
            this.lang               = lang;
            this.letterValue        = letterValue;
            this.groupingSeparator  = groupingSeparator;
            this.groupingSize       = groupingSeparator.Length > 0 ? groupingSize : 0;

            if (formatString == "1" || formatString.Length == 0) {
                // Special case of the default format
                return;
            }

            this.tokens = new List<TokenInfo>();
            int idxStart = 0;
            bool isAlphaNumeric = CharUtil.IsAlphaNumeric(formatString[idxStart]);

            if (isAlphaNumeric) {
                // If the first one is alpha num add empty separator as a prefix
                tokens.Add(null);
            }

            for (int idx = 0; idx <= formatString.Length; idx++) {
                // Loop until a switch from formatString token to separator is detected (or vice-versa)
                if (idx == formatString.Length || isAlphaNumeric != CharUtil.IsAlphaNumeric(formatString[idx])) {
                    if (isAlphaNumeric) {
                        // Just finished a format token
                        tokens.Add(TokenInfo.CreateFormat(formatString, idxStart, idx - idxStart));
                    } else {
                        // Just finished a separator token
                        tokens.Add(TokenInfo.CreateSeparator(formatString, idxStart, idx - idxStart));
                    }

                    // Begin parsing the next format token or separator
                    idxStart = idx;

                    // Flip flag from format token to separator or vice-versa
                    isAlphaNumeric = !isAlphaNumeric;
                }
            }
        }