private string GetExpressionString(Token[] reversedPolishNotation)
{
StringBuilder result = new StringBuilder();
foreach (var token in reversedPolishNotation)
{
if (token.Type == TokenType.Number)
{
result.Append(" " + token.Value + " ");
}
else if (token.Type == TokenType.Operator)
{
switch (token.OperatorType)
{
case OperatorType.Addition:
result.Append(" + ");
break;
case OperatorType.Substraction:
result.Append(" - ");
break;
case OperatorType.Mulitiplication:
result.Append(" * ");
break;
case OperatorType.Partition:
result.Append(" / ");
break;
case OperatorType.UnaryMinus:
result.Append(" _ ");
break;
}
}
else if (token.Type == TokenType.Function)
{
switch (token.FunctionType)
{
case FunctionType.Log:
result.Append(" LOG ");
break;
case FunctionType.Sqrt:
result.Append(" SQRT ");
break;
case FunctionType.Pow:
result.Append(" POW ");
break;
}
}
}
return result.ToString();
}
private double Calculate(Token[] reversedPolishNotation)
{
Stack<Token> numberStack = new Stack<Token>();
for (int index = 0; index < reversedPolishNotation.Length; index++)
{
if (reversedPolishNotation[index].Type == TokenType.Number)
{
numberStack.Push(reversedPolishNotation[index]);
}
else
{
if (reversedPolishNotation[index].Type == TokenType.Operator)
{
List<Token> operands = new List<Token>();
for (int count = 0; count < reversedPolishNotation[index].OperandsCount; count++)
{
operands.Add(numberStack.Pop());
}
numberStack.Push(ExecuteOperation(operands, reversedPolishNotation[index].OperatorType));
}
else if (reversedPolishNotation[index].Type == TokenType.Function)
{
List<Token> operands = new List<Token>();
for (int count = 0; count < reversedPolishNotation[index].OperandsCount; count++)
{
operands.Add(numberStack.Pop());
}
numberStack.Push(ExecuteFunction(operands, reversedPolishNotation[index].FunctionType));
}
}
}
if (numberStack.Count == 1)
{
return numberStack.Pop().Value;
}
else
{
throw new Exception("Invalid expression");
}
}
