// Syntax analysis of reverse polish notation expression
private Stack <double> SyntaxAnalysisRPN(Stack <double> stack, string token)
{
// if it's operand then just push to stack
if (token[0] == NumberMarker[0])
{
stack.Push(double.Parse(token.Remove(0, 1)));
}
// otherwise apply operator or funtion to elements in stack
else if (NumberOfArguments(token) == 1)
{
double argument = stack.Pop();
NumExpression arg = new NumExpression(argument);
if (!isRadians)
{
argument = argument * Math.PI / 180; // Convert value to degree
}
NumExpression trigArg = new NumExpression(argument);
double result;
switch (token)
{
case UnaryPlus:
result = arg.evaluate();
break;
case UnaryMinus:
NegateExpresion neg = new NegateExpresion(arg);
result = neg.evaluate();
break;
case Sqrt:
SqrtExpression sqrt = new SqrtExpression(arg);
result = sqrt.evaluate();
break;
case Log:
LogarithmExpression log = new LogarithmExpression(arg);
result = log.evaluate();
break;
case Ln:
LnExpression ln = new LnExpression(arg);
result = ln.evaluate();
break;
case Sin:
SinExpression sin = new SinExpression(trigArg);
result = sin.evaluate();
break;
case Cos:
CosExpression cos = new CosExpression(trigArg);
result = cos.evaluate();
break;
case Tan:
TanExpression tan = new TanExpression(trigArg);
result = tan.evaluate();
break;
case Csc:
CscExpression csc = new CscExpression(trigArg);
result = csc.evaluate();
break;
case Sec:
SecExpression sec = new SecExpression(trigArg);
result = sec.evaluate();
break;
case Cot:
CotExpression cot = new CotExpression(trigArg);
result = cot.evaluate();
break;
default:
throw new ArgumentException("Unknown operator");
}
stack.Push(result);
}
else
{
// otherwise operator's number of arguments equal to 2
double argument2 = stack.Pop();
double argument1 = stack.Pop();
NumExpression arg1 = new NumExpression(argument1);
NumExpression arg2 = new NumExpression(argument2);
double result;
switch (token)
{
case Plus:
AdditionExpression add = new AdditionExpression(arg1, arg2);
result = add.evaluate();
break;
case Minus:
MinusExpression minus = new MinusExpression(arg1, arg2);
result = minus.evaluate();
break;
case Multiply:
MultiplyExpression multiply = new MultiplyExpression(arg1, arg2);
result = multiply.evaluate();
break;
case Divide:
if (argument2 == 0)
{
throw new DivideByZeroException("Second argument is zero");
}
DivideExpression divide = new DivideExpression(arg1, arg2);
result = divide.evaluate();
break;
case Mod:
ModExpression mod = new ModExpression(arg1, arg2);
result = mod.evaluate();
break;
case Exponent:
ExpononetExpression exp = new ExpononetExpression(arg1, arg2);
result = exp.evaluate();
break;
default: throw new ArgumentException("Unknown operator");
}
stack.Push(result);
}
return(stack);
}
public virtual void Visit(NumExpression expression)
{
VisitSubNodes(expression);
}
