private static ReverseStringBuilder StringWithGroups(int capacity, IEnumerable <char> builder, int[] groupingSizes, string groupingSeparator)
{
var newBuffer = new ReverseStringBuilder(capacity);
using (var enumerator = builder.GetEnumerator())
{
if (!enumerator.MoveNext())
{
return(newBuffer);
}
foreach (var size in groupingSizes)
{
for (var count = size - 1; count >= 0; count--)
{
newBuffer.Prepend(enumerator.Current);
if (!enumerator.MoveNext())
{
return(newBuffer);
}
}
newBuffer.Prepend(groupingSeparator);
}
{
var size = groupingSizes[groupingSizes.Length - 1];
if (size != 0)
{
while (true)
{
for (var count = size - 1; count >= 0; count--)
{
newBuffer.Prepend(enumerator.Current);
if (!enumerator.MoveNext())
{
return(newBuffer);
}
}
newBuffer.Prepend(groupingSeparator);
}
}
while (true)
{
newBuffer.Prepend(enumerator.Current);
if (!enumerator.MoveNext())
{
return(newBuffer);
}
}
}
}
}
internal static string FormatBigInteger(BigInteger value, string format, NumberFormatInfo info)
{
var fmt = ParseFormatSpecifier(format, out var digits);
switch (fmt)
{
case 'x':
case 'X':
return(FormatBigIntegerToHexString(value, fmt, digits, info));
case 'e':
case 'E':
{
var precision = digits != -1 ? digits : 6;
if (value.InternalBits == null)
{
return(value.InternalSign.ToString(format, info));
}
var scale = (int)Math.Floor(Log10(value));
// ---
if (scale > precision + 10)
{
do
{
value /= 1000000000;
} while (Log10(value) > precision + 10);
}
while (Log10(value) > precision + 2)
{
value /= 10;
}
if (Log10(value) > precision + 1)
{
var round = value % 10 >= 5;
value = (value / 10) + (round ? One : Zero);
}
ReverseStringBuilder builder;
if (value.InternalBits == null)
{
builder = new ReverseStringBuilder(10);
builder.Prepend($"{value.InternalSign:D}");
}
else
{
builder = CreateBuilder(value, info, false, 0);
}
// ---
var decimalSeparator = info.NumberDecimalSeparator;
var result = new StringBuilder(builder.Length + 6);
var extra = 0;
if (precision >= builder.Length)
{
extra = precision - (builder.Length - 1);
precision = builder.Length - 1;
}
result.Append(builder.ToString(builder.Length, 1));
result.Append(decimalSeparator);
result.Append(builder.ToString(builder.Length - 1, precision));
result.Append(new string('0', extra));
result.Append(fmt);
result.Append(info.PositiveSign);
if (scale < 10)
{
result.Append("00");
}
else if (scale < 100)
{
result.Append('0');
}
result.Append(scale);
return(result.ToString());
}
default:
{
var decimalFmt = fmt == 'g' || fmt == 'G' || fmt == 'd' || fmt == 'D' || fmt == 'r' || fmt == 'R';
if (value.InternalBits == null)
{
if (fmt == 'g' || fmt == 'G' || fmt == 'r' || fmt == 'R')
{
format = digits > 0 ? "D" + digits.ToString(CultureInfo.InvariantCulture) : "D";
}
return(value.InternalSign.ToString(format, info));
}
var builder = CreateBuilder(value, info, decimalFmt, digits);
if (decimalFmt)
{
// Format Round-trip decimal
// This format is supported for integral types only. The number is converted to a string of
// decimal digits (0-9), prefixed by a minus sign if the number is negative. The precision
// specifier indicates the minimum number of digits desired in the resulting string. If required,
// the number is padded with zeros to its left to produce the number of digits given by the
// precision specifier.
while (digits > 0 && digits >= builder.Length)
{
builder.Prepend('0');
digits--;
}
if (value.InternalSign < 0)
{
builder.Prepend(info.NegativeSign);
}
return(builder.ToString());
}
// 'c', 'C', 'e', 'E', 'f', 'F', 'n', 'N', 'p', 'P', custom
var precision = -1;
var groupingSizes = new[] { 3 };
var groupingSeparator = info.NumberGroupSeparator;
var decimalSeparator = info.NumberDecimalSeparator;
var groups = false;
var type = 0;
switch (fmt)
{
case '\0':
// parse custom
break;
case 'c':
case 'C':
decimalSeparator = info.CurrencyDecimalSeparator;
precision = digits != -1 ? digits : info.CurrencyDecimalDigits;
groupingSeparator = info.CurrencyGroupSeparator;
groupingSizes = info.CurrencyGroupSizes;
groups = true;
type = 1;
break;
case 'f':
case 'F':
precision = digits != -1 ? digits : info.NumberDecimalDigits;
break;
case 'n':
case 'N':
precision = digits != -1 ? digits : info.NumberDecimalDigits;
groups = true;
break;
case 'p':
case 'P':
decimalSeparator = info.PercentDecimalSeparator;
precision = digits != -1 ? digits : info.PercentDecimalDigits;
groups = true;
type = 2;
break;
default:
throw new NotSupportedException();
}
var result = new StringBuilder(builder.Length + 20);
var close = SetWrap(value, info, type, result);
var append = builder;
if (groups)
{
var extra = groupingSizes.Length - 1;
if (groupingSizes[groupingSizes.Length - 1] != 0)
{
var totalDigits = builder.Length;
extra += (int)Math.Ceiling(totalDigits * 1.0 / groupingSizes[groupingSizes.Length - 1]);
}
var length = extra + builder.Length;
if (type == 2)
{
length += 2;
append = StringWithGroups(length, new ExtendedEnumerable <char>(new[] { '0', '0' }, builder), groupingSizes, groupingSeparator);
}
else
{
append = StringWithGroups(length, builder, groupingSizes, groupingSeparator);
}
}
result.Append(append);
if (precision > 0)
{
result.Append(decimalSeparator);
result.Append(new string('0', precision));
}
result.Append(close);
return(result.ToString());
}
}
}
private static ReverseStringBuilder CreateBuilder(BigInteger value, NumberFormatInfo info, bool decimalFmt, int digits)
{
// First convert to base 10^9.
const uint NumericBase = 1000000000; // 10^9
const int NumericBaseLog10 = 9;
var sourceLength = Length(value.InternalBits);
int maxConvertedLength;
try
{
maxConvertedLength = checked (sourceLength * 10 / 9 + 2);
}
catch (OverflowException e)
{
throw new FormatException("The value is too large to be represented by this format specifier.", e);
}
var converted = new uint[maxConvertedLength];
var convertedLength = 0;
for (var sourceIndex = sourceLength; --sourceIndex >= 0;)
{
// Take a cipher from the source
var carry = value.InternalBits[sourceIndex];
// Add it to converted
for (var convertedIndex = 0; convertedIndex < convertedLength; convertedIndex++)
{
var cipherBlock = NumericsHelpers.MakeUlong(converted[convertedIndex], carry);
converted[convertedIndex] = (uint)(cipherBlock % NumericBase);
carry = (uint)(cipherBlock / NumericBase);
}
if (carry != 0)
{
converted[convertedLength++] = carry % NumericBase;
carry /= NumericBase;
if (carry != 0)
{
converted[convertedLength++] = carry;
}
}
}
int stringCapacity;
try
{
// Each uint contributes at most 9 digits to the decimal representation.
stringCapacity = checked (convertedLength * NumericBaseLog10);
}
catch (OverflowException e)
{
throw new FormatException("The value is too large to be represented by this format specifier.", e);
}
if (decimalFmt)
{
if (digits > 0 && stringCapacity < digits)
{
stringCapacity = digits;
}
if (value.InternalSign < 0)
{
try
{
// Leave an extra slot for a minus sign.
stringCapacity = checked (stringCapacity + info.NegativeSign.Length);
}
catch (OverflowException e)
{
throw new FormatException("The value is too large to be represented by this format specifier.", e);
}
}
}
var result = new ReverseStringBuilder(stringCapacity);
for (var stringIndex = 0; stringIndex < convertedLength - 1; stringIndex++)
{
var cipherBlock = converted[stringIndex];
for (var cch = NumericBaseLog10; --cch >= 0;)
{
result.Prepend((char)('0' + cipherBlock % 10));
cipherBlock /= 10;
}
}
for (var cipherBlock = converted[convertedLength - 1]; cipherBlock != 0;)
{
result.Prepend((char)('0' + cipherBlock % 10));
cipherBlock /= 10;
}
return(result);
}
