/// <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);
}
