private void ResolveSummandToList(Summand summand, List <Summand> list)
{
Summand matchingVariable = list.Find(x =>
x.Variable.Equals(summand.Variable) && x.Order == summand.Order);
if (matchingVariable != null)
{
matchingVariable.Coefficient += summand.Coefficient;
if (summand.IsRhSide)
{
matchingVariable.IsRhSide = summand.IsRhSide;
}
}
else
{
list.Add(summand);
}
}
private void ProcessSummands(string inputString, List <Summand> list, char startingOperation)
{
string coefficient = String.Empty;
string variable = String.Empty;
string exponent = String.Empty;
char operation = OperationConstants.PLUS_SIGN;
bool isRhSide = false;
bool isRaisedToExp = false;
bool isNumExpected = false;
bool safeToResolve = false;
Summand summand;
for (int i = 0; i < inputString.Length; i++)
{
char value = inputString[i];
if (Char.IsWhiteSpace(value))
{
continue;
}
if (IsBracket(value))
{
int bracketIndex = FindBracketIndex(inputString.Substring(i));
string bracketSubString = inputString.Substring(i + 1, bracketIndex - 1);
if (startingOperation == operation)
{
ProcessSummands(bracketSubString, list, OperationConstants.PLUS_SIGN);
}
else
{
ProcessSummands(bracketSubString, list, OperationConstants.MINUS_SIGN);
}
i += bracketIndex;
continue;
}
if (IsOperation(value))
{
if (isNumExpected)
{
throw new Exception();
}
isRaisedToExp = false;
if (value == OperationConstants.EXPONENT_SIGN)
{
if (!String.IsNullOrEmpty(variable))
{
isRaisedToExp = true;
isNumExpected = true;
safeToResolve = false;
}
else
{
throw new Exception();
}
}
if (value == OperationConstants.EQUAL_SIGN)
{
if (safeToResolve)
{
summand = new Summand(coefficient, exponent, variable, operation, isRhSide);
if (startingOperation.Equals(OperationConstants.MINUS_SIGN))
{
summand.Coefficient = summand.Coefficient * -1;
}
ResolveSummandToList(summand, list);
coefficient = String.Empty;
variable = String.Empty;
exponent = String.Empty;
operation = OperationConstants.PLUS_SIGN;
isRaisedToExp = false;
safeToResolve = false;
isNumExpected = false;
}
else if (list.Count.Equals(0))
{
throw new Exception();
}
isRhSide = true;
}
else if (value == OperationConstants.MINUS_SIGN)
{
if (safeToResolve)
{
summand = new Summand(coefficient, exponent, variable, operation, isRhSide);
if (startingOperation.Equals(OperationConstants.MINUS_SIGN))
{
summand.Coefficient = summand.Coefficient * -1;
}
ResolveSummandToList(summand, list);
coefficient = String.Empty;
variable = String.Empty;
exponent = String.Empty;
isRaisedToExp = false;
safeToResolve = false;
isNumExpected = false;
operation = OperationConstants.MINUS_SIGN;
}
else
{
if (String.IsNullOrEmpty(coefficient) && String.IsNullOrEmpty(variable) &&
operation == OperationConstants.MINUS_SIGN)
{
operation = OperationConstants.PLUS_SIGN;
}
else
{
operation = OperationConstants.MINUS_SIGN;
}
}
}
else if (value == OperationConstants.PLUS_SIGN)
{
if (safeToResolve)
{
summand = new Summand(coefficient, exponent, variable, operation, isRhSide);
if (startingOperation.Equals(OperationConstants.MINUS_SIGN))
{
summand.Coefficient = summand.Coefficient * -1;
}
ResolveSummandToList(summand, list);
coefficient = String.Empty;
variable = String.Empty;
exponent = String.Empty;
isRaisedToExp = false;
safeToResolve = false;
isNumExpected = false;
operation = OperationConstants.PLUS_SIGN;
}
else
{
operation = OperationConstants.PLUS_SIGN;
}
}
}
else if (Char.IsNumber(value) || value == '.')
{
if (String.IsNullOrEmpty(variable))
{
coefficient += value;
isNumExpected = false;
}
else if (isRaisedToExp)
{
exponent += value;
isNumExpected = false;
}
else
{
throw new Exception();
}
}
else if (Char.IsLetter(value))
{
if (!isRaisedToExp)
{
variable += value;
isNumExpected = false;
}
else
{
throw new Exception();
}
}
if (!String.IsNullOrEmpty(coefficient) || !String.IsNullOrEmpty(variable))
{
if (!isNumExpected)
{
safeToResolve = true;
}
}
}
summand = new Summand(coefficient, exponent, variable, operation, isRhSide);
if (startingOperation.Equals(OperationConstants.MINUS_SIGN))
{
summand.Coefficient = summand.Coefficient * -1;
}
ResolveSummandToList(summand, list);
}