public static double EvaluateExpression(string strExp)
{
Stack <AbstractExpression> stack = new Stack <AbstractExpression>();
string[] tokenList = strExp.Split(' ');
foreach (string s in tokenList)
{
if (IsOperator(s))
{
AbstractExpression rightExpression = stack.Pop();
Console.WriteLine("Pop: " + rightExpression.Interpret());
AbstractExpression leftExpression = stack.Pop();
Console.WriteLine("Pop: " + leftExpression.Interpret());
AbstractExpression op = GetOperatorExpression(s, leftExpression, rightExpression);
Console.WriteLine("Applica operatore: " + s);
double result = op.Interpret();
stack.Push(new NumberExpression(result));
Console.WriteLine("Push result: " + result);
}
else
{
AbstractExpression i = new NumberExpression(s);
Console.WriteLine("Push: " + s);
stack.Push(i);
}
}
AbstractExpression exp = stack.Pop();
return(exp.Interpret());
}
public Expression Evaluate(String s)
{
int pos = s.Length - 1;
while (pos > 0)
{
if (Char.IsDigit(s[pos]))
{
pos--;
}
else
{
Expression left = Evaluate(s.Substring(0, pos));
int number = int.Parse(s.Substring(pos + 1));
Expression right = new NumberExpression(number);
Char oprt = s[pos];
switch (oprt.ToString())
{
case "-": return(new MinusExpression(left, right));
case "+": return(new PlusExpression(left, right));
}
}
}
int result = int.Parse(s);
return(new NumberExpression(result));
}
public IExpression Evaluate(string s)
{
int pos = s.Length - 1;
while (pos > 0)
{
if (Char.IsDigit(s[pos]))
{
pos--;
}
else
{
IExpression left = Evaluate(s.Substring(0, pos));
IExpression right = new NumberExpression(int.Parse(s.Substring(pos + 1, s.Length - pos - 1)));
char oper = s[pos];
switch (oper)
{
case '-':
return(new MinusExpression(left, right));
break;
case '+':
return(new PlusExpression(left, right));
break;
}
}
}
int result = int.Parse(s);
return(new NumberExpression(result));
}
