//holds operands and alwasys both
//however if exactly unary function - meaningfull just right
//the left will be empty
public Operation(string name, FormulaObject _left, FormulaObject _right)
{
if (!OperationDictionary.ContainsKey(name))
{
throw new Exception("Unacceptable formula : " + name);
}
index = OperationDictionary[name];
left = _left;
right = _right;
wasActivated = false;
}
//this class reshape the text of formula to
//it's binary tree of computing
//so any node (which roly is being playing by FormulaObject - it's just node container)
//contains either operation and forks (operands) or constant
//so we need FormulaObject just for these purpose - unified Container
public Function(string formula)
{
if (formula == null)
{
throw new Exception("Empty Formula");
}
formula = formula.ToLower().Trim(' ');
//there the formula is being prePared for parsing and transforms onto simplified form
List <FormulaObject> parsedFormula = new List <FormulaObject>();
parsedFormula = new List <FormulaObject>();
//this list will hold the sequence of recognized FormulaObjects
int parenthesesCounter = 0;
//if we need to properly parse formula we have to notify if parentheses are positioned correctly
//therefore keep the count of still opened parentheses
for (int i = 0; i < formula.Length;)
//and going through the text formula
{
if (formula[i] == '(')
//if we meet the Opening Parenthese - we are looking for it's end
//if there is no end - "parenthesesCounter" will let us know
{
parenthesesCounter++;
string inParenteses = "";
//here will be the part which stay in parentheses
++i;
while (i < formula.Length && parenthesesCounter > 0)
//going down and seek the end
//by the way recording the internal part
{
if (formula[i] == '(')
{
parenthesesCounter++;
}
if (formula[i] == ')')
{
parenthesesCounter--;
}
if (parenthesesCounter > 0)
{
inParenteses += formula[i];
}
i++;
}
Function FuncinParentheses = new Function(inParenteses);
//we need to calculate the part in parentheses earlier than any another operation
//so let's assume this part is independent formula
// and put on this place already parsed tree of it
parsedFormula.Add(FuncinParentheses.root);
i++;
}
else if (Char.IsDigit(formula[i]))
//here we check if numeric value was began parsing
//and in the same way recognise it's value and create constant, adding it to formula
{
double value = 0;
while (i < formula.Length && Char.IsDigit(formula[i]))
{
value = value * 10 + formula[i++] - '0';
}
if (i < formula.Length && (formula[i] == '.' || formula[i] == ','))
{
++i;
double divider = 10;
while (i < formula.Length && Char.IsDigit(formula[i]))
{
value += (formula[i++] - '0') / divider;
divider *= 10;
}
}
parsedFormula.Add(new Const(value));
}
else if (Operation.CharIsOperatorPart(formula[i]))
//if char is operator part - we need to read only one it's symbol
//there is impossible to let the operator have two symbols by the definition
//try to define it and push back to the parsed formula
{
if (formula[i] == '-' &&
(parsedFormula.Count == 0 ||
(parsedFormula[parsedFormula.Count - 1] is Operation) &&
(parsedFormula[parsedFormula.Count - 1] as Operation).index < 13))
{
parsedFormula.Add(new Operation("opposite", new FormulaObject(), new FormulaObject()));
i++;
}
else
{
parsedFormula.Add(new Operation("" + formula[i++], new FormulaObject(), new FormulaObject()));
}
//here is solving the problem of '-' definition
//it can be the unary and equally likely to be binary
//so we need to look it's predecessor
//if const - only binary, else - only unary because of standart math syntax
}
else if (Operation.CharIsMethodPart(formula[i]))
{
string formulaName = "";
while (i < formula.Length && Operation.CharIsMethodPart(formula[i]))
{
formulaName += formula[i++];
}
parsedFormula.Add(new Operation(formulaName, new FormulaObject(), new FormulaObject()));
//here we read the full operation (Method) name and push it at the end of formula
}
else if (formula[i++] != ' ')
{
throw new Exception("Unacceptable symbol : " + formula[i]);
}
}
if (parenthesesCounter != 0)
{
throw new Exception("Uncorrect parentheses arrangement");
}
//and we should check if all parentheses are correct
//if not - stop working - the result has no matter
for (int priority = 10; priority > 0; --priority)
//looking for the most priority operations in funtion
//and assign them their operands
//there we must use field wasActivated not to let operators be assigned twice
{
for (int i = parsedFormula.Count - 1; i >= 0; --i)
{
if (parsedFormula[i] is Operation &&
(parsedFormula[i] as Operation).Priority() == priority &&
(parsedFormula[i] as Operation).ArgumentsCount() == 1 &&
(parsedFormula[i] as Operation).wasActivated == false)
{
(parsedFormula[i] as Operation).right = parsedFormula[i + 1];
(parsedFormula[i] as Operation).wasActivated = true;
parsedFormula.RemoveAt(i + 1);
}
}
//check the unary functions from right to left
//note: to let cos cos cos cos x be computed witho
for (int i = 0; i < parsedFormula.Count; ++i)
{
if (parsedFormula[i] is Operation &&
(parsedFormula[i] as Operation).Priority() == priority &&
(parsedFormula[i] as Operation).ArgumentsCount() == 2 &&
(parsedFormula[i] as Operation).wasActivated == false)
{
(parsedFormula[i] as Operation).right = parsedFormula[i + 1];
(parsedFormula[i] as Operation).left = parsedFormula[i - 1];
(parsedFormula[i] as Operation).wasActivated = true;
parsedFormula.RemoveAt(i + 1);
parsedFormula.RemoveAt(i - 1);
i = 0;
}
}
//and the binary from left to right
}
if (parsedFormula.Count != 1)
{
throw new Exception("Unacceptable formula");
}
//check all formula was reduced up to singular tree
root = parsedFormula[0];
}
