private static bool TryFormatInt64MultipleDigits(long value, Span <byte> destination, out int bytesWritten)
{
if (value < 0)
{
value = -value;
int digitCount = FormattingHelpers.CountDigits((ulong)value);
// WriteDigits does not do bounds checks
if (digitCount >= destination.Length)
{
bytesWritten = 0;
return(false);
}
destination[0] = Utf8Constants.Minus;
bytesWritten = digitCount + 1;
FormattingHelpers.WriteDigits((ulong)value, destination.Slice(1, digitCount));
return(true);
}
else
{
return(TryFormatUInt64MultipleDigits((ulong)value, destination, out bytesWritten));
}
}
// Split long into two parts that can each fit in a uint - {1-10 digits}{9 digits}
private static bool TryFormatInt64MoreThanNegativeBillionMaxUInt(long value, Span <byte> destination, out int bytesWritten)
{
uint overNineDigits = (uint)(value / Utf8Constants.Billion);
uint lastNineDigits = (uint)(value - (overNineDigits * Utf8Constants.Billion));
int digitCountOverNineDigits = FormattingHelpers.CountDigits(overNineDigits);
Debug.Assert(digitCountOverNineDigits >= 1 && digitCountOverNineDigits <= 10);
int digitCount = digitCountOverNineDigits + 9;
// WriteDigits does not do bounds checks
if (digitCount >= destination.Length)
{
bytesWritten = 0;
return(false);
}
destination[0] = Utf8Constants.Minus;
bytesWritten = digitCount + 1;
FormattingHelpers.WriteDigits(overNineDigits, destination.Slice(1, digitCountOverNineDigits));
FormattingHelpers.WriteDigits(lastNineDigits, destination.Slice(digitCountOverNineDigits + 1, 9));
return(true);
}
private static bool TryFormatUInt64N(ulong value, byte precision, Span <byte> buffer, out int bytesWritten)
{
if (value <= long.MaxValue)
{
return(TryFormatInt64N((long)value, precision, buffer, out bytesWritten));
}
// The ulong path is much slower than the long path here, so we are doing the last group
// inside this method plus the zero padding but routing to the long version for the rest.
value = FormattingHelpers.DivMod(value, 1000, out ulong lastGroup);
if (!TryFormatInt64N((long)value, 0, buffer, out bytesWritten))
{
return(false);
}
if (precision == StandardFormat.NoPrecision)
{
precision = 2;
}
int idx = bytesWritten;
// Since this method routes entirely to the long version if the number is smaller than
// long.MaxValue, we are guaranteed to need to write 3 more digits here before the set
// of trailing zeros.
bytesWritten += 4; // 3 digits + group separator
if (precision > 0)
{
bytesWritten += precision + 1; // +1 for period.
}
if (buffer.Length < bytesWritten)
{
bytesWritten = 0;
return(false);
}
ref byte utf8Bytes = ref buffer.DangerousGetPinnableReference();
private static bool TryFormatUInt64(ulong value, Span <byte> destination, out int bytesWritten, StandardFormat format)
{
if (format.IsDefault)
{
return(TryFormatUInt64Default(value, destination, out bytesWritten));
}
switch (format.Symbol)
{
case 'G':
case 'g':
case 'R':
case 'r': // treat 'R'/'r' (which historically was only for floating-point) as being equivalent to 'g', rather than throwing
if (format.HasPrecision)
{
throw new NotSupportedException(SR.Argument_GWithPrecisionNotSupported); // With a precision, 'G' can produce exponential format, even for integers.
}
return(TryFormatUInt64D(value, format.Precision, destination, insertNegationSign: false, out bytesWritten));
case 'd':
case 'D':
return(TryFormatUInt64D(value, format.Precision, destination, insertNegationSign: false, out bytesWritten));
case 'n':
case 'N':
return(TryFormatUInt64N(value, format.Precision, destination, insertNegationSign: false, out bytesWritten));
case 'x':
return(TryFormatUInt64X(value, format.Precision, true /* useLower */, destination, out bytesWritten));
case 'X':
return(TryFormatUInt64X(value, format.Precision, false /* useLower */, destination, out bytesWritten));
default:
return(FormattingHelpers.TryFormatThrowFormatException(out bytesWritten));
}
}
private static bool TryFormatUInt64MoreThanBillionMaxUInt(ulong value, Span <byte> destination, out int bytesWritten)
{
ulong overNineDigits = value / Utf8Constants.Billion;
uint lastNineDigits = (uint)(value - (overNineDigits * Utf8Constants.Billion));
uint overEighteenDigits = (uint)(overNineDigits / Utf8Constants.Billion);
uint middleNineDigits = (uint)(overNineDigits - (overEighteenDigits * Utf8Constants.Billion));
int digitCountOverEighteenDigits = FormattingHelpers.CountDigits(overEighteenDigits);
Debug.Assert(digitCountOverEighteenDigits >= 1 && digitCountOverEighteenDigits <= 2);
int digitCount = digitCountOverEighteenDigits + 18;
// WriteDigits does not do bounds checks
if (digitCount > destination.Length)
{
bytesWritten = 0;
return(false);
}
bytesWritten = digitCount;
FormattingHelpers.WriteDigits(overEighteenDigits, destination.Slice(0, digitCountOverEighteenDigits));
FormattingHelpers.WriteDigits(middleNineDigits, destination.Slice(digitCountOverEighteenDigits, 9));
FormattingHelpers.WriteDigits(lastNineDigits, destination.Slice(digitCountOverEighteenDigits + 9, 9));
return(true);
}
/// <summary>
/// Formats a Guid as a UTF8 string.
/// </summary>
/// <param name="value">Value to format</param>
/// <param name="destination">Buffer to write the UTF8-formatted value to</param>
/// <param name="bytesWritten">Receives the length of the formatted text in bytes</param>
/// <param name="format">The standard format to use</param>
/// <returns>
/// true for success. "bytesWritten" contains the length of the formatted text in bytes.
/// false if buffer was too short. Iteratively increase the size of the buffer and retry until it succeeds.
/// </returns>
/// <remarks>
/// Formats supported:
/// D (default) nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn
/// B {nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn}
/// P (nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn)
/// N nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryFormat(Guid value, Span <byte> destination, out int bytesWritten, StandardFormat format = default)
{
const int INSERT_DASHES = unchecked ((int)0x80000000);
const int NO_DASHES = 0;
const int INSERT_CURLY_BRACES = (CloseBrace << 16) | (OpenBrace << 8);
const int INSERT_ROUND_BRACES = (CloseParen << 16) | (OpenParen << 8);
const int NO_BRACES = 0;
const int LEN_GUID_BASE = 32;
const int LEN_ADD_DASHES = 4;
const int LEN_ADD_BRACES = 2;
// This is a 32-bit value whose contents (where 0 is the low byte) are:
// 0th byte: minimum required length of the output buffer,
// 1st byte: the ASCII byte to insert for the opening brace position (or 0 if no braces),
// 2nd byte: the ASCII byte to insert for the closing brace position (or 0 if no braces),
// 3rd byte: high bit set if dashes are to be inserted.
//
// The reason for keeping a single flag instead of separate vars is that we can avoid register spillage
// as we build up the output value.
int flags;
switch (FormattingHelpers.GetSymbolOrDefault(format, 'D'))
{
case 'D': // nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn
flags = INSERT_DASHES + NO_BRACES + LEN_GUID_BASE + LEN_ADD_DASHES;
break;
case 'B': // {nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn}
flags = INSERT_DASHES + INSERT_CURLY_BRACES + LEN_GUID_BASE + LEN_ADD_DASHES + LEN_ADD_BRACES;
break;
case 'P': // (nnnnnnnn-nnnn-nnnn-nnnn-nnnnnnnnnnnn)
flags = INSERT_DASHES + INSERT_ROUND_BRACES + LEN_GUID_BASE + LEN_ADD_DASHES + LEN_ADD_BRACES;
break;
case 'N': // nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
flags = NO_BRACES + NO_DASHES + LEN_GUID_BASE;
break;
default:
return(ThrowHelper.TryFormatThrowFormatException(out bytesWritten));
}
// At this point, the low byte of flags contains the minimum required length
if ((byte)flags > destination.Length)
{
bytesWritten = 0;
return(false);
}
bytesWritten = (byte)flags;
flags >>= 8;
// At this point, the low byte of flags contains the opening brace char (if any)
if ((byte)flags != 0)
{
destination[0] = (byte)flags;
destination = destination.Slice(1);
}
flags >>= 8;
// At this point, the low byte of flags contains the closing brace char (if any)
// And since we're performing arithmetic shifting the high bit of flags is set (flags is negative) if dashes are required
DecomposedGuid guidAsBytes = default;
guidAsBytes.Guid = value;
// When a GUID is blitted, the first three components are little-endian, and the last component is big-endian.
// The line below forces the JIT to hoist the bounds check for the following segment.
// The JIT will optimize away the read, but it cannot optimize away the bounds check
// because it may have an observable side effect (throwing).
// We use 8 instead of 7 so that we also capture the dash if we're asked to insert one.
{ var unused = destination[8]; }
FormattingHelpers.WriteHexByte(guidAsBytes.Byte03, destination, 0, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte02, destination, 2, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte01, destination, 4, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte00, destination, 6, FormattingHelpers.HexCasing.Lowercase);
if (flags < 0 /* use dash? */)
{
destination[8] = Dash;
destination = destination.Slice(9);
}
else
{
destination = destination.Slice(8);
}
{ var unused = destination[4]; }
FormattingHelpers.WriteHexByte(guidAsBytes.Byte05, destination, 0, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte04, destination, 2, FormattingHelpers.HexCasing.Lowercase);
if (flags < 0 /* use dash? */)
{
destination[4] = Dash;
destination = destination.Slice(5);
}
else
{
destination = destination.Slice(4);
}
{ var unused = destination[4]; }
FormattingHelpers.WriteHexByte(guidAsBytes.Byte07, destination, 0, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte06, destination, 2, FormattingHelpers.HexCasing.Lowercase);
if (flags < 0 /* use dash? */)
{
destination[4] = Dash;
destination = destination.Slice(5);
}
else
{
destination = destination.Slice(4);
}
{ var unused = destination[4]; }
FormattingHelpers.WriteHexByte(guidAsBytes.Byte08, destination, 0, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte09, destination, 2, FormattingHelpers.HexCasing.Lowercase);
if (flags < 0 /* use dash? */)
{
destination[4] = Dash;
destination = destination.Slice(5);
}
else
{
destination = destination.Slice(4);
}
{ var unused = destination[11]; } // can't hoist bounds check on the final brace (if exists)
FormattingHelpers.WriteHexByte(guidAsBytes.Byte10, destination, 0, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte11, destination, 2, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte12, destination, 4, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte13, destination, 6, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte14, destination, 8, FormattingHelpers.HexCasing.Lowercase);
FormattingHelpers.WriteHexByte(guidAsBytes.Byte15, destination, 10, FormattingHelpers.HexCasing.Lowercase);
if ((byte)flags != 0)
{
destination[12] = (byte)flags;
}
return(true);
}
/// <summary>
/// Formats a TimeSpan as a UTF8 string.
/// </summary>
/// <param name="value">Value to format</param>
/// <param name="destination">Buffer to write the UTF8-formatted value to</param>
/// <param name="bytesWritten">Receives the length of the formatted text in bytes</param>
/// <param name="format">The standard format to use</param>
/// <returns>
/// true for success. "bytesWritten" contains the length of the formatted text in bytes.
/// false if buffer was too short. Iteratively increase the size of the buffer and retry until it succeeds.
/// </returns>
/// <remarks>
/// Formats supported:
/// c/t/T (default) [-][d.]hh:mm:ss[.fffffff] (constant format)
/// G [-]d:hh:mm:ss.fffffff (general long)
/// g [-][d:][h]h:mm:ss[.f[f[f[f[f[f[f]]]]]] (general short)
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryFormat(TimeSpan value, Span <byte> destination, out int bytesWritten, StandardFormat format = default)
{
char symbol = FormattingHelpers.GetSymbolOrDefault(format, 'c');
switch (symbol)
{
case 'c':
case 'G':
case 'g':
break;
case 't':
case 'T':
symbol = 'c';
break;
default:
return(FormattingHelpers.TryFormatThrowFormatException(out bytesWritten));
}
// First, calculate how large an output buffer is needed to hold the entire output.
int requiredOutputLength = 8; // start with "hh:mm:ss" and adjust as necessary
uint fraction;
ulong totalSecondsRemaining;
{
// Turn this into a non-negative TimeSpan if possible.
long ticks = value.Ticks;
if (ticks < 0)
{
ticks = -ticks;
if (ticks < 0)
{
Debug.Assert(ticks == long.MinValue /* -9223372036854775808 */);
// We computed these ahead of time; they're straight from the decimal representation of Int64.MinValue.
fraction = 4775808;
totalSecondsRemaining = 922337203685;
goto AfterComputeFraction;
}
}
ulong fraction64;
(totalSecondsRemaining, fraction64) = Math.DivRem((ulong)Math.Abs(value.Ticks), TimeSpan.TicksPerSecond);
fraction = (uint)fraction64;
}
AfterComputeFraction:
int fractionDigits = 0;
if (symbol == 'c')
{
// Only write out the fraction if it's non-zero, and in that
// case write out the entire fraction (all digits).
if (fraction != 0)
{
fractionDigits = Utf8Constants.DateTimeNumFractionDigits;
}
}
else if (symbol == 'G')
{
// Always write out the fraction, even if it's zero.
fractionDigits = Utf8Constants.DateTimeNumFractionDigits;
}
else
{
// Only write out the fraction if it's non-zero, and in that
// case write out only the most significant digits.
if (fraction != 0)
{
fractionDigits = Utf8Constants.DateTimeNumFractionDigits - FormattingHelpers.CountDecimalTrailingZeros(fraction, out fraction);
}
}
Debug.Assert(fraction < 10_000_000);
// If we're going to write out a fraction, also need to write the leading decimal.
if (fractionDigits != 0)
{
requiredOutputLength += fractionDigits + 1;
}
ulong totalMinutesRemaining = 0;
ulong seconds = 0;
if (totalSecondsRemaining > 0)
{
// Only compute minutes if the TimeSpan has an absolute value of >= 1 minute.
(totalMinutesRemaining, seconds) = Math.DivRem(totalSecondsRemaining, 60 /* seconds per minute */);
}
Debug.Assert(seconds < 60);
ulong totalHoursRemaining = 0;
ulong minutes = 0;
if (totalMinutesRemaining > 0)
{
// Only compute hours if the TimeSpan has an absolute value of >= 1 hour.
(totalHoursRemaining, minutes) = Math.DivRem(totalMinutesRemaining, 60 /* minutes per hour */);
}
Debug.Assert(minutes < 60);
// At this point, we can switch over to 32-bit divmod since the data has shrunk far enough.
Debug.Assert(totalHoursRemaining <= uint.MaxValue);
uint days = 0;
uint hours = 0;
if (totalHoursRemaining > 0)
{
// Only compute days if the TimeSpan has an absolute value of >= 1 day.
(days, hours) = Math.DivRem((uint)totalHoursRemaining, 24 /* hours per day */);
}
Debug.Assert(hours < 24);
int hourDigits = 2;
if (hours < 10 && symbol == 'g')
{
// Only writing a one-digit hour, not a two-digit hour
hourDigits--;
requiredOutputLength--;
}
int dayDigits = 0;
if (days == 0)
{
if (symbol == 'G')
{
requiredOutputLength += 2; // for the leading "0:"
dayDigits = 1;
}
}
else
{
dayDigits = FormattingHelpers.CountDigits(days);
requiredOutputLength += dayDigits + 1; // for the leading "d:" (or "d.")
}
if (value.Ticks < 0)
{
requiredOutputLength++; // for the leading '-' sign
}
if (destination.Length < requiredOutputLength)
{
bytesWritten = 0;
return(false);
}
bytesWritten = requiredOutputLength;
int idx = 0;
// Write leading '-' if necessary
if (value.Ticks < 0)
{
destination[idx++] = Utf8Constants.Minus;
}
// Write day (and separator) if necessary
if (dayDigits > 0)
{
FormattingHelpers.WriteDigits(days, destination.Slice(idx, dayDigits));
idx += dayDigits;
destination[idx++] = (symbol == 'c') ? Utf8Constants.Period : Utf8Constants.Colon;
}
// Write "[h]h:mm:ss"
FormattingHelpers.WriteDigits(hours, destination.Slice(idx, hourDigits));
idx += hourDigits;
destination[idx++] = Utf8Constants.Colon;
FormattingHelpers.WriteDigits((uint)minutes, destination.Slice(idx, 2));
idx += 2;
destination[idx++] = Utf8Constants.Colon;
FormattingHelpers.WriteDigits((uint)seconds, destination.Slice(idx, 2));
idx += 2;
// Write fraction (and separator) if necessary
if (fractionDigits > 0)
{
destination[idx++] = Utf8Constants.Period;
FormattingHelpers.WriteDigits(fraction, destination.Slice(idx, fractionDigits));
idx += fractionDigits;
}
// And we're done!
Debug.Assert(idx == requiredOutputLength);
return(true);
}
/// <summary>
/// Formats a Boolean as a UTF8 string.
/// </summary>
/// <param name="value">Value to format</param>
/// <param name="destination">Buffer to write the UTF8-formatted value to</param>
/// <param name="bytesWritten">Receives the length of the formatted text in bytes</param>
/// <param name="format">The standard format to use</param>
/// <returns>
/// true for success. "bytesWritten" contains the length of the formatted text in bytes.
/// false if buffer was too short. Iteratively increase the size of the buffer and retry until it succeeds.
/// </returns>
/// <remarks>
/// Formats supported:
/// G (default) True/False
/// l true/false
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryFormat(bool value, Span <byte> destination, out int bytesWritten, StandardFormat format = default)
{
char symbol = FormattingHelpers.GetSymbolOrDefault(format, 'G');
if (value)
{
if (symbol == 'G')
{
// By having each branch perform its own call to TryWriteUInt32BigEndian, we ensure that a
// constant value is passed to this routine, which means the compiler can reverse endianness
// at compile time instead of runtime if necessary.
const uint TrueValueUppercase = ('T' << 24) + ('r' << 16) + ('u' << 8) + ('e' << 0);
if (!BinaryPrimitives.TryWriteUInt32BigEndian(destination, TrueValueUppercase))
{
goto BufferTooSmall;
}
}
else if (symbol == 'l')
{
const uint TrueValueLowercase = ('t' << 24) + ('r' << 16) + ('u' << 8) + ('e' << 0);
if (!BinaryPrimitives.TryWriteUInt32BigEndian(destination, TrueValueLowercase))
{
goto BufferTooSmall;
}
}
else
{
goto BadFormat;
}
bytesWritten = 4;
return(true);
}
else
{
if (symbol == 'G')
{
// This check can't be performed earlier because we need to throw if an invalid symbol is
// provided, even if the buffer is too small.
if (destination.Length <= 4)
{
goto BufferTooSmall;
}
const uint FalsValueUppercase = ('F' << 24) + ('a' << 16) + ('l' << 8) + ('s' << 0);
BinaryPrimitives.WriteUInt32BigEndian(destination, FalsValueUppercase);
}
else if (symbol == 'l')
{
if (destination.Length <= 4)
{
goto BufferTooSmall;
}
const uint FalsValueLowercase = ('f' << 24) + ('a' << 16) + ('l' << 8) + ('s' << 0);
BinaryPrimitives.WriteUInt32BigEndian(destination, FalsValueLowercase);
}
else
{
goto BadFormat;
}
destination[4] = (byte)'e';
bytesWritten = 5;
return(true);
}
BufferTooSmall:
bytesWritten = 0;
return(false);
BadFormat:
return(FormattingHelpers.TryFormatThrowFormatException(out bytesWritten));
}
/// <summary>
/// Formats a TimeSpan as a UTF8 string.
/// </summary>
/// <param name="value">Value to format</param>
/// <param name="buffer">Buffer to write the UTF8-formatted value to</param>
/// <param name="bytesWritten">Receives the length of the formatted text in bytes</param>
/// <param name="format">The standard format to use</param>
/// <returns>
/// true for success. "bytesWritten" contains the length of the formatted text in bytes.
/// false if buffer was too short. Iteratively increase the size of the buffer and retry until it succeeds.
/// </returns>
/// <remarks>
/// Formats supported:
/// c/t/T (default) [-][d.]hh:mm:ss[.fffffff] (constant format)
/// G [-]d:hh:mm:ss.fffffff (general long)
/// g [-][d:]h:mm:ss[.f[f[f[f[f[f[f[]]]]]]] (general short)
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static bool TryFormat(TimeSpan value, Span <byte> buffer, out int bytesWritten, StandardFormat format = default)
{
char symbol = format.IsDefault ? 'c' : format.Symbol;
switch (symbol)
{
case 'G':
case 'g':
case 'c':
case 't':
case 'T':
{
bool longForm = (symbol == 'G');
bool constant = (symbol == 't' || symbol == 'T' || symbol == 'c');
long ticks = value.Ticks;
int days = (int)FormattingHelpers.DivMod(ticks, TimeSpan.TicksPerDay, out long timeLeft);
bool showSign = false;
if (ticks < 0)
{
showSign = true;
days = -days;
timeLeft = -timeLeft;
}
int hours = (int)FormattingHelpers.DivMod(timeLeft, TimeSpan.TicksPerHour, out timeLeft);
int minutes = (int)FormattingHelpers.DivMod(timeLeft, TimeSpan.TicksPerMinute, out timeLeft);
int seconds = (int)FormattingHelpers.DivMod(timeLeft, TimeSpan.TicksPerSecond, out long fraction);
int dayDigits = 0;
int hourDigits = (constant || longForm || hours > 9) ? 2 : 1;
int fractionDigits = 0;
bytesWritten = hourDigits + 6; // [h]h:mm:ss
if (showSign)
{
bytesWritten += 1; // [-]
}
if (longForm || days > 0)
{
dayDigits = FormattingHelpers.CountDigits(days);
bytesWritten += dayDigits + 1; // [d'.']
}
if (longForm || fraction > 0)
{
fractionDigits = (longForm || constant) ? Utf8Constants.DateTimeNumFractionDigits : FormattingHelpers.CountFractionDigits(fraction);
bytesWritten += fractionDigits + 1; // ['.'fffffff] or ['.'FFFFFFF] for short-form
}
if (buffer.Length < bytesWritten)
{
bytesWritten = 0;
return(false);
}
ref byte utf8Bytes = ref buffer.DangerousGetPinnableReference();
int idx = 0;
if (showSign)
{
Unsafe.Add(ref utf8Bytes, idx++) = Utf8Constants.Minus;
}
if (dayDigits > 0)
{
idx += FormattingHelpers.WriteDigits(days, dayDigits, ref utf8Bytes, idx);
Unsafe.Add(ref utf8Bytes, idx++) = constant ? Utf8Constants.Period : Utf8Constants.Colon;
}
idx += FormattingHelpers.WriteDigits(hours, hourDigits, ref utf8Bytes, idx);
Unsafe.Add(ref utf8Bytes, idx++) = Utf8Constants.Colon;
idx += FormattingHelpers.WriteDigits(minutes, 2, ref utf8Bytes, idx);
Unsafe.Add(ref utf8Bytes, idx++) = Utf8Constants.Colon;
idx += FormattingHelpers.WriteDigits(seconds, 2, ref utf8Bytes, idx);
if (fractionDigits > 0)
{
Unsafe.Add(ref utf8Bytes, idx++) = Utf8Constants.Period;
idx += FormattingHelpers.WriteFractionDigits(fraction, fractionDigits, ref utf8Bytes, idx);
}
return(true);
}
/// <summary>
/// Formats a Decimal as a UTF8 string.
/// </summary>
/// <param name="value">Value to format</param>
/// <param name="destination">Buffer to write the UTF8-formatted value to</param>
/// <param name="bytesWritten">Receives the length of the formatted text in bytes</param>
/// <param name="format">The standard format to use</param>
/// <returns>
/// true for success. "bytesWritten" contains the length of the formatted text in bytes.
/// false if buffer was too short. Iteratively increase the size of the buffer and retry until it succeeds.
/// </returns>
/// <remarks>
/// Formats supported:
/// G/g (default)
/// F/f 12.45 Fixed point
/// E/e 1.245000e1 Exponential
/// </remarks>
/// <exceptions>
/// <cref>System.FormatException</cref> if the format is not valid for this data type.
/// </exceptions>
public static unsafe bool TryFormat(decimal value, Span <byte> destination, out int bytesWritten, StandardFormat format = default)
{
if (format.IsDefault)
{
format = 'G';
}
switch (format.Symbol)
{
case 'g':
case 'G':
{
if (format.Precision != StandardFormat.NoPrecision)
{
throw new NotSupportedException(SR.Argument_GWithPrecisionNotSupported);
}
Number.NumberBuffer number = new Number.NumberBuffer(Number.NumberBufferKind.Decimal, stackalloc byte[Number.DecimalNumberBufferLength]);
Number.DecimalToNumber(ref value, ref number);
if (number.Digits[0] == 0)
{
number.IsNegative = false; // For Decimals, -0 must print as normal 0.
}
bool success = TryFormatDecimalG(ref number, destination, out bytesWritten);
#if DEBUG
// This DEBUG segment exists to close a code coverage hole inside TryFormatDecimalG(). Because we don't call RoundNumber() on this path, we have no way to feed
// TryFormatDecimalG() a number where trailing zeros before the decimal point have been cropped. So if the chance comes up, we'll crop the zeroes
// ourselves and make a second call to ensure we get the same outcome.
if (success)
{
Span <byte> digits = number.Digits;
int numDigits = number.DigitsCount;
if (numDigits != 0 && number.Scale == numDigits && digits[numDigits - 1] == '0')
{
while (numDigits != 0 && digits[numDigits - 1] == '0')
{
digits[numDigits - 1] = 0;
numDigits--;
}
number.DigitsCount = numDigits;
number.CheckConsistency();
byte[] buffer2 = new byte[destination.Length];
bool success2 = TryFormatDecimalG(ref number, buffer2, out int bytesWritten2);
Debug.Assert(success2);
Debug.Assert(bytesWritten2 == bytesWritten);
for (int i = 0; i < bytesWritten; i++)
{
Debug.Assert(destination[i] == buffer2[i]);
}
}
}
#endif // DEBUG
return(success);
}
case 'f':
case 'F':
{
Number.NumberBuffer number = new Number.NumberBuffer(Number.NumberBufferKind.Decimal, stackalloc byte[Number.DecimalNumberBufferLength]);
Number.DecimalToNumber(ref value, ref number);
byte precision = (format.Precision == StandardFormat.NoPrecision) ? (byte)2 : format.Precision;
Number.RoundNumber(ref number, number.Scale + precision, isCorrectlyRounded: false);
Debug.Assert((number.Digits[0] != 0) || !number.IsNegative); // For Decimals, -0 must print as normal 0. As it happens, Number.RoundNumber already ensures this invariant.
return(TryFormatDecimalF(ref number, destination, out bytesWritten, precision));
}
case 'e':
case 'E':
{
Number.NumberBuffer number = new Number.NumberBuffer(Number.NumberBufferKind.Decimal, stackalloc byte[Number.DecimalNumberBufferLength]);
Number.DecimalToNumber(ref value, ref number);
byte precision = (format.Precision == StandardFormat.NoPrecision) ? (byte)6 : format.Precision;
Number.RoundNumber(ref number, precision + 1, isCorrectlyRounded: false);
Debug.Assert((number.Digits[0] != 0) || !number.IsNegative); // For Decimals, -0 must print as normal 0. As it happens, Number.RoundNumber already ensures this invariant.
return(TryFormatDecimalE(ref number, destination, out bytesWritten, precision, exponentSymbol: (byte)format.Symbol));
}
default:
return(FormattingHelpers.TryFormatThrowFormatException(out bytesWritten));
}
}
private static bool TryFormatFloatingPoint <T>(T value, Span <byte> destination, out int bytesWritten, StandardFormat format) where T : IFormattable, ISpanFormattable
{
if (format.IsDefault)
{
format = 'G';
}
switch (format.Symbol)
{
case 'g':
case 'G':
if (format.Precision != StandardFormat.NoPrecision)
{
throw new NotSupportedException(SR.Argument_GWithPrecisionNotSupported);
}
break;
case 'f':
case 'F':
case 'e':
case 'E':
break;
default:
return(FormattingHelpers.TryFormatThrowFormatException(out bytesWritten));
}
Span <char> formatText = stackalloc char[StandardFormat.FormatStringLength];
int formattedLength = format.Format(formatText);
formatText = formatText.Slice(0, formattedLength);
// We first try to format into a stack-allocated buffer, and if it succeeds, we can avoid
// all allocation. If that fails, we fall back to allocating strings. If it proves impactful,
// that allocation (as well as roundtripping from byte to char and back to byte) could be avoided by
// calling into a refactored Number.FormatSingle/Double directly.
const int StackBufferLength = 128; // large enough to handle the majority cases
Span <char> stackBuffer = stackalloc char[StackBufferLength];
ReadOnlySpan <char> utf16Text = stackalloc char[0];
// Try to format into the stack buffer. If we're successful, we can avoid all allocations.
if (value.TryFormat(stackBuffer, out formattedLength, formatText, CultureInfo.InvariantCulture))
{
utf16Text = stackBuffer.Slice(0, formattedLength);
}
else
{
// The stack buffer wasn't large enough. If the destination buffer isn't at least as
// big as the stack buffer, we know the whole operation will eventually fail, so we
// can just fail now.
if (destination.Length <= StackBufferLength)
{
bytesWritten = 0;
return(false);
}
// Fall back to using a string format and allocating a string for the resulting formatted value.
utf16Text = value.ToString(new string(formatText), CultureInfo.InvariantCulture);
}
// Copy the value to the destination, if it's large enough.
if (utf16Text.Length > destination.Length)
{
bytesWritten = 0;
return(false);
}
for (int i = 0; i < utf16Text.Length; i++)
{
Debug.Assert(utf16Text[i] < 128, "A culture-invariant ToString() of a floating point expected to produce ASCII characters only.");
destination[i] = (byte)utf16Text[i];
}
bytesWritten = utf16Text.Length;
return(true);
}
