public Expression ToPolskExpression()
{
var res = new Expression();
var stack = new YourStack <ExpressionPart>(Elements.Count);
foreach (var el in Elements)
{
switch (el.Type)
{
case ExpressionPartType.OpenBracket:
stack.Push(el);
continue;
case ExpressionPartType.CloseBracket:
while (!stack.IsEmpty)
{
if (stack.Peek().Type == ExpressionPartType.OpenBracket)
{
stack.Pop();
break;
}
res.Elements.Add(stack.Pop());
}
continue;
case ExpressionPartType.Number:
res.Elements.Add(el);
continue;
case ExpressionPartType.OrdinaryOperation:
case ExpressionPartType.BinaryOperation:
if (stack.IsEmpty)
{
stack.Push(el);
}
else
{
while (true)
{
if (stack.IsEmpty || el.Rating > stack.Peek().Rating)
{
stack.Push(el);
break;
}
else
{
res.Elements.Add(stack.Pop());
}
}
}
continue;
}
}
while (!stack.IsEmpty)
{
res.Elements.Add(stack.Pop());
}
return(res);
}
public double Calculate()
{
var exp = ToPolskExpression();
var stack = new YourStack <ExpressionPart>(exp.Elements.Count);
foreach (var el in exp.Elements)
{
if (el.Type == ExpressionPartType.Number)
{
stack.Push(el);
}
else if (el.Type == ExpressionPartType.BinaryOperation)
{
var e2 = stack.Pop().Number;
var e1 = stack.Pop().Number;
stack.Push(new ExpressionPart(el.Operation.OperationFunction(e1, e2)));
}
else if (el.Type == ExpressionPartType.OrdinaryOperation)
{
stack.Push(new ExpressionPart(el.Operation.OperationFunction(stack.Pop().Number)));
}
}
return(stack.Pop().Number);
}