public static long ParseInt64(ReadOnlySpan <char> value)
{
if (value.IsEmpty)
{
throw new FormatException(MemoryProvider.BadFormat);
}
long result = 0;
int i = 0;
int end = value.Length;
var state = ParseState.LeadingWhite;
bool negative = false;
//skip leading whitespaces
while (i < end && JsonUtils.IsWhiteSpace(value[i]))
{
i++;
}
if (i == end)
{
throw new FormatException(MemoryProvider.BadFormat);
}
//skip leading zeros
while (i < end && value[i] == '0')
{
state = ParseState.Number;
i++;
}
while (i < end)
{
var c = value[i++];
switch (state)
{
case ParseState.LeadingWhite:
if (c == '-')
{
negative = true;
state = ParseState.Sign;
}
else if (c == '0')
{
state = ParseState.TrailingWhite;
}
else if (c > '0' && c <= '9')
{
result = -(c - '0');
state = ParseState.Number;
}
else
{
throw new FormatException(MemoryProvider.BadFormat);
}
break;
case ParseState.Sign:
if (c == '0')
{
state = ParseState.TrailingWhite;
}
else if (c > '0' && c <= '9')
{
result = -(c - '0');
state = ParseState.Number;
}
else
{
throw new FormatException(MemoryProvider.BadFormat);
}
break;
case ParseState.Number:
if (c >= '0' && c <= '9')
{
checked
{
result = 10 * result - (c - '0');
}
if (result < minValue
) //check only minvalue, because in absolute value it's greater than maxvalue
{
throw DefaultMemory.CreateOverflowException(maxValue);
}
}
else if (JsonUtils.IsWhiteSpace(c))
{
state = ParseState.TrailingWhite;
}
else
{
throw new FormatException(MemoryProvider.BadFormat);
}
break;
case ParseState.TrailingWhite:
if (JsonUtils.IsWhiteSpace(c))
{
state = ParseState.TrailingWhite;
}
else
{
throw new FormatException(MemoryProvider.BadFormat);
}
break;
}
}
if (state != ParseState.Number && state != ParseState.TrailingWhite)
{
throw new FormatException(MemoryProvider.BadFormat);
}
if (negative)
{
return(result);
}
checked
{
result = -result;
}
if (result > maxValue)
{
throw DefaultMemory.CreateOverflowException(maxValue);
}
return(result);
}
internal static ulong ParseUInt64(ReadOnlySpan<char> value)
{
if (value.IsEmpty)
throw new FormatException(MemoryProvider.BadFormat);
ulong result = 0;
int i = 0;
int end = value.Length;
var state = ParseState.LeadingWhite;
//skip leading whitespaces
while (i < end && JsonUtils.IsWhiteSpace(value[i])) i++;
if (i == end)
throw new FormatException(MemoryProvider.BadFormat);
//skip leading zeros
while (i < end && value[i] == '0')
{
state = ParseState.Number;
i++;
}
while (i < end)
{
var c = value[i++];
switch (state)
{
case ParseState.LeadingWhite:
if (JsonUtils.IsWhiteSpace(c))
break;
if (c == '0')
{
state = ParseState.TrailingWhite;
}
else if (c > '0' && c <= '9')
{
result = (ulong) (c - '0');
state = ParseState.Number;
}
else throw new FormatException(MemoryProvider.BadFormat);
break;
case ParseState.Number:
if (c >= '0' && c <= '9')
{
checked
{
result = 10 * result + (ulong) (c - '0');
}
if (result > maxValue
) //check only minvalue, because in absolute value it's greater than maxvalue
throw DefaultMemory.CreateOverflowException(maxValue);
}
else if (JsonUtils.IsWhiteSpace(c))
{
state = ParseState.TrailingWhite;
}
else throw new FormatException(MemoryProvider.BadFormat);
break;
case ParseState.TrailingWhite:
if (JsonUtils.IsWhiteSpace(c))
{
state = ParseState.TrailingWhite;
}
else throw new FormatException(MemoryProvider.BadFormat);
break;
}
}
if (state != ParseState.Number && state != ParseState.TrailingWhite)
throw new FormatException(MemoryProvider.BadFormat);
return result;
}