private static ParseResult <Period> RepeatedUnit(ValueCursor cursor, char unitCharacter) => ParseResult <Period> .ForInvalidValue(cursor, TextErrorMessages.RepeatedUnitSpecifier, unitCharacter);
// TODO(misc): Tidy this up a *lot*.
public ParseResult <Period> Parse(string text)
{
if (text is null)
{
return(ParseResult <Period> .ArgumentNull("text"));
}
if (text.Length == 0)
{
return(ParseResult <Period> .ValueStringEmpty);
}
ValueCursor valueCursor = new ValueCursor(text);
valueCursor.MoveNext();
if (valueCursor.Current != 'P')
{
return(ParseResult <Period> .MismatchedCharacter(valueCursor, 'P'));
}
bool inDate = true;
PeriodBuilder builder = new PeriodBuilder();
PeriodUnits unitsSoFar = 0;
while (valueCursor.MoveNext())
{
if (inDate && valueCursor.Current == 'T')
{
inDate = false;
continue;
}
bool negative = valueCursor.Current == '-';
var failure = valueCursor.ParseInt64 <Period>(out long unitValue);
if (failure != null)
{
return(failure);
}
if (valueCursor.Length == valueCursor.Index)
{
return(ParseResult <Period> .EndOfString(valueCursor));
}
// Various failure cases:
// - Repeated unit (e.g. P1M2M)
// - Time unit is in date part (e.g. P5M)
// - Date unit is in time part (e.g. PT1D)
// - Unit is in incorrect order (e.g. P5D1Y)
// - Unit is invalid (e.g. P5J)
// - Unit is missing (e.g. P5)
PeriodUnits unit;
switch (valueCursor.Current)
{
case 'Y': unit = PeriodUnits.Years; break;
case 'M': unit = inDate ? PeriodUnits.Months : PeriodUnits.Minutes; break;
case 'W': unit = PeriodUnits.Weeks; break;
case 'D': unit = PeriodUnits.Days; break;
case 'H': unit = PeriodUnits.Hours; break;
case 'S': unit = PeriodUnits.Seconds; break;
case ',':
case '.': unit = PeriodUnits.Nanoseconds; break; // Special handling below
default: return(InvalidUnit(valueCursor, valueCursor.Current));
}
if ((unit & unitsSoFar) != 0)
{
return(RepeatedUnit(valueCursor, valueCursor.Current));
}
// This handles putting months before years, for example. Less significant units
// have higher integer representations.
if (unit < unitsSoFar)
{
return(MisplacedUnit(valueCursor, valueCursor.Current));
}
// The result of checking "there aren't any time units in this unit" should be
// equal to "we're still in the date part".
if ((unit & PeriodUnits.AllTimeUnits) == 0 != inDate)
{
return(MisplacedUnit(valueCursor, valueCursor.Current));
}
// Seen a . or , which need special handling.
if (unit == PeriodUnits.Nanoseconds)
{
// Check for already having seen seconds, e.g. PT5S0.5
if ((unitsSoFar & PeriodUnits.Seconds) != 0)
{
return(MisplacedUnit(valueCursor, valueCursor.Current));
}
builder.Seconds = unitValue;
if (!valueCursor.MoveNext())
{
return(ParseResult <Period> .MissingNumber(valueCursor));
}
// Can cope with at most 999999999 nanoseconds
if (!valueCursor.ParseFraction(9, 9, out int totalNanoseconds, 1))
{
return(ParseResult <Period> .MissingNumber(valueCursor));
}
// Use whether or not the seconds value was negative (even if 0)
// as the indication of whether this value is negative.
if (negative)
{
totalNanoseconds = -totalNanoseconds;
}
builder.Milliseconds = (totalNanoseconds / NanosecondsPerMillisecond) % MillisecondsPerSecond;
builder.Ticks = (totalNanoseconds / NanosecondsPerTick) % TicksPerMillisecond;
builder.Nanoseconds = totalNanoseconds % NanosecondsPerTick;
if (valueCursor.Current != 'S')
{
return(ParseResult <Period> .MismatchedCharacter(valueCursor, 'S'));
}
if (valueCursor.MoveNext())
{
return(ParseResult <Period> .ExpectedEndOfString(valueCursor));
}
return(ParseResult <Period> .ForValue(builder.Build()));
}
builder[unit] = unitValue;
unitsSoFar |= unit;
}
if (unitsSoFar == 0)
{
return(ParseResult <Period> .ForInvalidValue(valueCursor, TextErrorMessages.EmptyPeriod));
}
return(ParseResult <Period> .ForValue(builder.Build()));
}
private static ParseResult <Period> InvalidUnit(ValueCursor cursor, char unitCharacter) => ParseResult <Period> .ForInvalidValue(cursor, Messages.Parse_InvalidUnitSpecifier, unitCharacter);
private static ParseResult <Period> MisplacedUnit(ValueCursor cursor, char unitCharacter)
{
return(ParseResult <Period> .ForInvalidValue(cursor, Messages.Parse_MisplacedUnitSpecifier, unitCharacter));
}
private static ParseResult <Period> RepeatedUnit(char unitCharacter)
{
return(ParseResult <Period> .ForInvalidValue(Messages.Parse_RepeatedUnitSpecifier, unitCharacter));
}
