C# FormattingData.TryWriteSymbol方法代码示例

        internal static bool TryFormatInt64(long value, byte numberOfBytes, Span<byte> buffer, Format.Parsed format, FormattingData formattingData, out int bytesWritten)
        {
            Precondition.Require(numberOfBytes <= sizeof(long));

            if (value >= 0)
            {
                return TryFormatUInt64(unchecked((ulong)value), numberOfBytes, buffer, format, formattingData, out bytesWritten);
            }
            else if (format.IsHexadecimal)
            {
                ulong bitMask = GetBitMask(numberOfBytes);
                return TryFormatUInt64(unchecked((ulong)value) & bitMask, numberOfBytes, buffer, format, formattingData, out bytesWritten);
            }
            else
            {
                int minusSignBytes = 0;
                if(!formattingData.TryWriteSymbol(FormattingData.Symbol.MinusSign, buffer, out minusSignBytes))
                {
                    bytesWritten = 0;
                    return false;
                }

                int digitBytes = 0;
                if(!TryFormatUInt64(unchecked((ulong)-value), numberOfBytes, buffer.Slice(minusSignBytes), format, formattingData, out digitBytes))
                {
                    bytesWritten = 0;
                    return false;
                }
                bytesWritten = digitBytes + minusSignBytes;
                return true;
            }
        }

        public static bool TryFormatNumber(double value, bool isSingle, Span<byte> buffer, Format.Parsed format, FormattingData formattingData, out int bytesWritten)
        {
            Precondition.Require(format.Symbol == 'G' || format.Symbol == 'E' || format.Symbol == 'F');

            bytesWritten = 0;
            int written;

            if (Double.IsNaN(value))
            {
                return formattingData.TryWriteSymbol(FormattingData.Symbol.NaN, buffer, out bytesWritten);
            }

            if (Double.IsInfinity(value))
            {
                if (Double.IsNegativeInfinity(value))
                {
                    if (!formattingData.TryWriteSymbol(FormattingData.Symbol.MinusSign, buffer, out written))
                    {
                        bytesWritten = 0;
                        return false;
                    }
                    bytesWritten += written;
                }
                if (!formattingData.TryWriteSymbol(FormattingData.Symbol.InfinitySign, buffer.Slice(bytesWritten), out written))
                {
                    bytesWritten = 0;
                    return false;
                }
                bytesWritten += written;
                return true;
            }

            // TODO: the lines below need to be replaced with properly implemented algorithm
            // the problem is the algorithm is complex, so I am commiting a stub for now
            var hack = value.ToString(format.Symbol.ToString());
            return hack.TryFormat(buffer, default(Format.Parsed), formattingData, out bytesWritten);
        }

        // TODO: this whole routine is too slow. It does div and mod twice, which are both costly (especially that some JITs cannot optimize it).
        // It does it twice to avoid reversing the formatted buffer, which can be tricky given it should handle arbitrary cultures.
        // One optimization I thought we could do is to do div/mod once and store digits in a temp buffer (but that would allocate). Modification to the idea would be to store the digits in a local struct
        // Another idea possibly worth tying would be to special case cultures that have constant digit size, and go back to the format + reverse buffer approach.
        private static bool TryFormatDecimal(ulong value, Span<byte> buffer, Format.Parsed format, FormattingData formattingData, out int bytesWritten)
        {
            if(format.IsDefault)
            {
                format.Symbol = 'G';
            }
            format.Symbol = Char.ToUpperInvariant(format.Symbol); // TODO: this is costly. I think the transformation should happen in Parse
            Precondition.Require(format.Symbol == 'D' || format.Symbol == 'G' || format.Symbol == 'N');

            // Reverse value on decimal basis, count digits and trailing zeros before the decimal separator
            ulong reversedValueExceptFirst = 0;
            var digitsCount = 1;
            var trailingZerosCount = 0;

            // We reverse the digits in numeric form because reversing encoded digits is hard and/or costly.
            // If value contains 20 digits, its reversed value will not fit into ulong size.
            // So reverse it till last digit (reversedValueExceptFirst will have all the digits except the first one).
            while (value >= 10)
            {
                var digit = value % 10UL;
                value = value / 10UL;

                if (reversedValueExceptFirst == 0 && digit == 0)
                {
                    trailingZerosCount++;
                }
                else
                {
                    reversedValueExceptFirst = reversedValueExceptFirst * 10UL + digit;
                    digitsCount++;
                }
            }

            bytesWritten = 0;
            int digitBytes;
            // If format is D and precision is greater than digitsCount + trailingZerosCount, append leading zeros
            if (format.Symbol == 'D' && format.HasPrecision)
            {
                var leadingZerosCount = format.Precision - digitsCount - trailingZerosCount;
                while (leadingZerosCount-- > 0)
                {
                    if (!formattingData.TryWriteDigitOrSymbol(0, buffer.Slice(bytesWritten), out digitBytes))
                    {
                        bytesWritten = 0;
                        return false;
                    }
                    bytesWritten += digitBytes;
                }
            }

            // Append first digit
            if (!formattingData.TryWriteDigit(value, buffer.Slice(bytesWritten), out digitBytes))
            {
                bytesWritten = 0;
                return false;
            }
            bytesWritten += digitBytes;
            digitsCount--;

            if (format.Symbol == 'N')
            {
                const int GroupSize = 3;

                // Count amount of digits before first group separator. It will be reset to groupSize every time digitsLeftInGroup == zero
                var digitsLeftInGroup = (digitsCount + trailingZerosCount) % GroupSize;
                if (digitsLeftInGroup == 0)
                {
                    if (digitsCount + trailingZerosCount > 0)
                    {
                        // There is a new group immediately after the first digit
                        if (!formattingData.TryWriteSymbol(FormattingData.Symbol.GroupSeparator, buffer.Slice(bytesWritten), out digitBytes))
                        {
                            bytesWritten = 0;
                            return false;
                        }
                        bytesWritten += digitBytes;
                    }
                    digitsLeftInGroup = GroupSize;
                }

                // Append digits
                while (reversedValueExceptFirst > 0)
                {
                    if (digitsLeftInGroup == 0)
                    {
                        if (!formattingData.TryWriteSymbol(FormattingData.Symbol.GroupSeparator, buffer.Slice(bytesWritten), out digitBytes))
                        {
                            bytesWritten = 0;
                            return false;
                        }
                        bytesWritten += digitBytes;
                        digitsLeftInGroup = GroupSize;
                    }

                    var nextDigit = reversedValueExceptFirst % 10UL;
                    reversedValueExceptFirst = reversedValueExceptFirst / 10UL;
//.........这里部分代码省略.........