private static int FindLastOerationWithPriorityPlusMinus(string input)
{
var bracketsLevel = BracketsHelper.BracketsLevel(input: input);
int lastOperationIndex = 0;
bool multDivOperationHasBeenFound = false;
bool powerOperationHasBeenFound = false;
for (var index = input.Length - 1; index >= 0; index--)
{
if ((input[index] == CalculationConstants.Plus || input[index] == CalculationConstants.Minus) &&
bracketsLevel[index] == 0)
{
lastOperationIndex = index;
break;
}
else if ((input[index] == CalculationConstants.Multiply || input[index] == CalculationConstants.Divide) &&
bracketsLevel[index] == 0 && !multDivOperationHasBeenFound)
{
lastOperationIndex = index;
multDivOperationHasBeenFound = true;
}
else if (input[index] == CalculationConstants.Power &&
bracketsLevel[index] == 0 && !multDivOperationHasBeenFound && !powerOperationHasBeenFound)
{
lastOperationIndex = index;
powerOperationHasBeenFound = true;
}
}
return(lastOperationIndex);
}
/// <summary>
/// Returnes an edited input for separation into nodes.
/// If input isn't valid to make a node tree, throws appropriate exception
/// </summary>
internal static string VerifyInput(string input, CultureInfo culture)
{
var editedInput = RemoveWhiteSpaces(input: input);
editedInput = CheckInput(input: editedInput, culture: culture);
editedInput = RemoveGroupSeparator(input: editedInput, culture: culture);
editedInput = BracketsHelper.TrimBrackets(input: editedInput);
editedInput = editedInput.Replace(CalculationConstants.PiChar.ToString(), Math.PI.ToString(culture));
return(editedInput);
}
private static ICalculationOperation MakeNode(string input, CultureInfo culture)
{
ICalculationOperation node = null;
if (input.Any(character => CalculationConstants.PlusMinMultDivPow.Contains(character)))
{
node = SplitToNodes(input: input, culture: culture);
}
else
{
input = BracketsHelper.TrimBrackets(input);
node = new Number(value: decimal.Parse(input, culture));
}
return(node);
}
private static ICalculationOperation SplitToNodes(string input, CultureInfo culture)
{
input = BracketsHelper.TrimBrackets(input);
// Since people read from left to right, to ensure the correct order of operations,
// node tree should be built from right to left with priority of operations outside brackets:
// plus or minus, multply or divide, power.
int lastOperationIndex = FindLastOerationWithPriorityPlusMinus(input: input);
var rightString = input.Substring(lastOperationIndex + 1);
var leftString = input.Substring(0, lastOperationIndex);
var operation = input[lastOperationIndex];
ICalculationOperation node = null;
ICalculationOperation leftOperand = MakeNode(input: leftString, culture: culture);
ICalculationOperation rightOperand = MakeNode(input: rightString, culture: culture);
switch (operation)
{
case CalculationConstants.Plus:
node = new Addition(leftOperand, rightOperand);
break;
case CalculationConstants.Minus:
node = new Subtraction(leftOperand, rightOperand);
break;
case CalculationConstants.Divide:
node = new Division(leftOperand, rightOperand);
break;
case CalculationConstants.Multiply:
node = new Multiplication(leftOperand, rightOperand);
break;
case CalculationConstants.Power:
node = new ToThePower(leftOperand, rightOperand);
break;
}
return(node);
}