private static Exception?CheckRepeatedDigits(string roman, RomanizerOptions options)
{
var allowFourSum = options.HasFlag(RomanizerOptions.ALLOW_FOUR_SEQUENTIAL_DIGITS);
var allowMultipleSum = options.HasFlag(RomanizerOptions.ALLOW_MULTIPLE_SEQUENTIAL_DIGITS);
for (var i = 0; i < roman.Length; i++)
{
var current = roman[i];
var totalRepeated = (byte)roman.Skip(i).TakeWhile(digit => digit == current).Count();
switch (totalRepeated)
{
case <= 3:
continue;
case 4 when !allowFourSum:
return(new ArithmeticAdditionException(
roman, current, totalRepeated,
$"Roman number '{roman}' with multiple repeated digits of '{current}' with total '{totalRepeated}', so it is invalid roman number. If you want sum 4 digits you need allow this in options entry."));
case > 4 when !allowMultipleSum:
return(new ArithmeticAdditionException(
roman, current, totalRepeated,
$"Roman number '{roman}' with multiple repeated digits of '{current}' with total '{totalRepeated}', so it is invalid roman number. If you want sum more than 4 digits you need allow this in options entry."));
}
}
return(null);
}
internal static string RomanizeUnsafe(ushort number, RomanizerOptions options = RomanizerOptions.DEFAULT_STRICT)
{
StringBuilder roman = new(MAX_VALUE_ROMAN.Length);
do
{
for (var i = 0; i < romanNumbersReversed.Count(); i++)
{
var(romanDigit, decimalDigit) = romanNumbersReversed.ElementAt(i);
if (number < decimalDigit)
{
continue;
}
var count = (ushort)Math.Round((double)(number / decimalDigit));
/*
* Special rule
*
* When the number have free 4 units, need subtract then by higher value for not throw 4 sum limit.
*
* Example: IIII => IV
*/
var isSpecialCountRule = count == 4 && !options.HasFlag(RomanizerOptions.ALLOW_FOUR_SEQUENTIAL_DIGITS);
if (isSpecialCountRule)
{
var higherValueIndex = i - 1;
var(rightRomanDigit, rightDigit) = romanNumbersReversed.ElementAtOrDefault(higherValueIndex);
var existRightValue = rightRomanDigit != 0 && rightDigit > 0;
/*
* Need check if have higher value to subtract free units
*/
if (existRightValue)
{
roman.Append(romanDigit);
roman.Append(rightRomanDigit);
number -= (ushort)(decimalDigit * count);
break;
}
}
/*
* Special rule end
*/
for (var j = 0; j < count; j++)
{
roman.Append(romanDigit);
}
number -= (ushort)(decimalDigit * count);
break;
}
} while (number > 0);
return(roman.ToString());
}
private static void CheckSpecialRules(char left, char right, char current, int rightValue,
RomanizerOptions options)
{
var isNotStrict = !options.HasFlag(RomanizerOptions.DEFAULT_STRICT);
if (isNotStrict)
{
return;
}
var isAddition = Util.ConvertSingleRomanToDecimal(current) >= rightValue;
if (isAddition)
{
CheckAdditionSpecialRules(current, rightValue, options);
}
else
{
CheckSubtractionSpecialRules(left, right, current, options);
}
}
