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

        public DecimalFormatter(string formatPicture, DecimalFormat decimalFormat) {
            Debug.Assert(formatPicture != null && decimalFormat != null);
            if (formatPicture.Length == 0) {
                throw XsltException.Create(Res.Xslt_InvalidFormat);
            }

            zeroDigit = decimalFormat.zeroDigit;
            posFormatInfo = (NumberFormatInfo)decimalFormat.info.Clone();
            StringBuilder temp = new StringBuilder();

            bool integer = true;
            bool sawPattern = false, sawZeroDigit = false, sawDigit = false, sawDecimalSeparator = false;
            bool digitOrZeroDigit = false;
            char decimalSeparator = posFormatInfo.NumberDecimalSeparator[0];
            char groupSeparator   = posFormatInfo.NumberGroupSeparator[0];
            char percentSymbol    = posFormatInfo.PercentSymbol[0];
            char perMilleSymbol   = posFormatInfo.PerMilleSymbol[0];

            int commaIndex = 0;
            int groupingSize = 0;
            int decimalIndex = -1;
            int lastDigitIndex = -1;

            for (int i = 0; i < formatPicture.Length; i++) {
                char ch = formatPicture[i];

                if (ch == decimalFormat.digit) {
                    if (sawZeroDigit && integer) {
                        throw XsltException.Create(Res.Xslt_InvalidFormat1, formatPicture);
                    }
                    lastDigitIndex = temp.Length;
                    sawDigit = digitOrZeroDigit = true;
                    temp.Append('#');
                    continue;
                }
                if (ch == decimalFormat.zeroDigit) {
                    if (sawDigit && !integer) {
                        throw XsltException.Create(Res.Xslt_InvalidFormat2, formatPicture);
                    }
                    lastDigitIndex = temp.Length;
                    sawZeroDigit = digitOrZeroDigit = true;
                    temp.Append('0');
                    continue;
                }
                if (ch == decimalFormat.patternSeparator) {
                    if (!digitOrZeroDigit) {
                        throw XsltException.Create(Res.Xslt_InvalidFormat8);
                    }
                    if (sawPattern) {
                        throw XsltException.Create(Res.Xslt_InvalidFormat3, formatPicture);
                    }
                    sawPattern = true;

                    if (decimalIndex < 0) {
                        decimalIndex = lastDigitIndex + 1;
                    }
                    groupingSize = RemoveTrailingComma(temp, commaIndex, decimalIndex);

                    if (groupingSize > 9) {
                        groupingSize = 0;
                    }
                    posFormatInfo.NumberGroupSizes = new int[] { groupingSize };
                    if (!sawDecimalSeparator) {
                        posFormatInfo.NumberDecimalDigits = 0;
                    }

                    posFormat = temp.ToString();

                    temp.Length = 0;
                    decimalIndex = -1;
                    lastDigitIndex = -1;
                    commaIndex = 0;
                    sawDigit = sawZeroDigit = digitOrZeroDigit = false;
                    sawDecimalSeparator = false;
                    integer = true;
                    negFormatInfo = (NumberFormatInfo)decimalFormat.info.Clone();
                    negFormatInfo.NegativeSign = string.Empty;
                    continue;
                }
                if (ch == decimalSeparator) {
                    if (sawDecimalSeparator) {
                        throw XsltException.Create(Res.Xslt_InvalidFormat5, formatPicture);
                    }
                    decimalIndex = temp.Length;
                    sawDecimalSeparator = true;
                    sawDigit = sawZeroDigit = integer = false;
                    temp.Append('.');
                    continue;
                }
                if (ch == groupSeparator) {
                    commaIndex = temp.Length;
                    lastDigitIndex = commaIndex;
                    temp.Append(',');
                    continue;
                }
                if (ch == percentSymbol) {
                    temp.Append('%');
                    continue;
                }
                if (ch == perMilleSymbol) {
                    temp.Append('\u2030');
                    continue;
                }
                if (ch == '\'') {
                    int pos = formatPicture.IndexOf('\'', i + 1);
                    if (pos < 0) {
                        pos = formatPicture.Length - 1;
                    }
                    temp.Append(formatPicture, i, pos - i + 1);
                    i = pos;
                    continue;
                }
                // Escape literal digits with EscChar, double literal EscChar
                if ('0' <= ch && ch <= '9' || ch == EscChar) {
                    if (decimalFormat.zeroDigit != '0') {
                        temp.Append(EscChar);
                    }
                }
                // Escape characters having special meaning for CLR
                if (ClrSpecialChars.IndexOf(ch) >= 0) {
                    temp.Append('\\');
                }
                temp.Append(ch);
            }

            if (!digitOrZeroDigit) {
                throw XsltException.Create(Res.Xslt_InvalidFormat8);
            }
            NumberFormatInfo formatInfo = sawPattern ? negFormatInfo : posFormatInfo;

            if (decimalIndex < 0) {
                decimalIndex = lastDigitIndex + 1;
            }
            groupingSize = RemoveTrailingComma(temp, commaIndex, decimalIndex);
            if (groupingSize > 9) {
                groupingSize = 0;
            }
            formatInfo.NumberGroupSizes = new int[] { groupingSize };
            if (!sawDecimalSeparator) {
                formatInfo.NumberDecimalDigits = 0;
            }

            if (sawPattern) {
                negFormat = temp.ToString();
            } else {
                posFormat = temp.ToString();
            }
        }