private static void Append(DiceExpression dice, ParseValues parseValues)
{
int constant = int.Parse(parseValues.Constant, CultureInfo.CurrentCulture);
if (parseValues.Multiplicity == 0)
{
dice.Constant(parseValues.Scalar * constant);
}
else
{
dice.Dice(parseValues.Multiplicity, constant, parseValues.Scalar, parseValues.Choose);
}
}
/// <summary>
/// Create a new DiceExpression by parsing the specified string.
/// </summary>
/// <param name="expression">A dice notation string expression. Ex. 3d6+3.</param>
/// <returns>A Dice Expression parsed from the specified string.</returns>
/// <exception cref="ArgumentException">Invalid dice notation supplied</exception>
public DiceExpression Parse(string expression)
{
if (string.IsNullOrEmpty(expression))
{
throw new ArgumentException("A dice notation expression must be supplied.", nameof(expression));
}
string cleanExpression = whitespacePattern.Replace(expression.ToLower(), "");
cleanExpression = cleanExpression.Replace("+-", "-");
ParseValues parseValues = new ParseValues().Init();
var dice = new DiceExpression();
for (int i = 0; i < cleanExpression.Length; i++)
{
char c = cleanExpression[i];
if (char.IsDigit(c))
{
parseValues.Constant += c.ToString();
}
else if (c == '*')
{
parseValues.Scalar *= int.Parse(parseValues.Constant, CultureInfo.CurrentCulture);
parseValues.Constant = string.Empty;
}
else if (c == 'd')
{
if (parseValues.Constant.Length == 0)
{
parseValues.Constant = "1";
}
parseValues.Multiplicity = int.Parse(parseValues.Constant, CultureInfo.CurrentCulture);
parseValues.Constant = string.Empty;
}
else if (c == 'k')
{
string chooseAccum = string.Empty;
while (i + 1 < cleanExpression.Length && char.IsDigit(cleanExpression[i + 1]))
{
chooseAccum += cleanExpression[i + 1].ToString();
i++;
}
parseValues.Choose = int.Parse(chooseAccum, CultureInfo.CurrentCulture);
}
else if (c == '+')
{
Append(dice, parseValues);
parseValues = new ParseValues().Init();
}
else if (c == '-')
{
Append(dice, parseValues);
parseValues = new ParseValues().Init();
parseValues.Scalar = -1;
}
else
{
throw new ArgumentException("Invalid character in dice expression", nameof(expression));
}
}
Append(dice, parseValues);
return(dice);
}