public double Compute()
{
Stack<Token> compu_stack = new Stack<Token>();
try{
foreach(Token tok in calc_list){
Token res = new Token();
if(tok._class == (int)type.num || tok._class == (int)type.var){
compu_stack.Push(tok);
}else if(tok._class == (int)type.op){
Token rhs = compu_stack.Pop();
Token lhs = compu_stack.Pop();
switch (tok.repr)
{
case "+":
res.repr = (double.Parse(GetValue(lhs)) + double.Parse(GetValue(rhs))).ToString();
compu_stack.Push(res);
break;
case "-":
res.repr = (double.Parse(GetValue(lhs)) - double.Parse(GetValue(rhs))).ToString();
compu_stack.Push(res);
break;
case "/":
res.repr = (double.Parse(GetValue(lhs)) / double.Parse(GetValue(rhs))).ToString();
compu_stack.Push(res);
break;
case "*":
res.repr = (double.Parse(GetValue(lhs)) * double.Parse(GetValue(rhs))).ToString();
compu_stack.Push(res);
break;
default:
return double.Parse(compu_stack.Pop().repr);
}
}
}
return double.Parse(GetValue(compu_stack.Pop()));
}catch(Exception ex){
throw new Exception("Expression not well formed.", ex);
}
}
private bool RPN(string expression)
{
Regex reg = new Regex(@"\[\b[A-Za-z]+\b(?![\d])\]|[\+\-/\*]|[\d]+(\.[\d]+)?|[()]");
Stack<Token> op_stack = new Stack<Token>();
foreach(Match token in reg.Matches(expression)){
Token tok = new Token();
string value = token.Captures[0].Value;
if(IsNumeric(value)){
tok._class = (int)type.num;
tok.repr = value;
calc_list.Add(tok);
}else if(IsOperator(value)){
while(op_stack.Count != 0 && op_stack.Peek().repr != "("){
if (HasPrecidenceOrEqual(op_stack.Peek().repr, value)){
calc_list.Add(op_stack.Pop());
}
else break;
}
tok._class = (int)type.op;
tok.repr = value;
op_stack.Push(tok);
}else if (IsVariable(value)){
tok._class = (int)type.var;
tok.repr = value;
calc_list.Add(tok);
}else if(value == "("){
tok._class = (int)type.var;
tok.repr = value;
op_stack.Push(tok);
}else if(value == ")"){
while(op_stack.Count != 0 && op_stack.Peek().repr != "("){
calc_list.Add(op_stack.Pop());
}
if (op_stack.Count != 0) op_stack.Pop();
}
}
while(op_stack.Count != 0){
calc_list.Add(op_stack.Pop());
}
return true;
}
private string GetValue(Token input)
{
if(input._class == (int)type.num){
return input.repr;
}else{
return data_store[input.repr].ToString();
}
}