//Helper funton used to get the value of the var or const node with relation to the operand node
public double evalSubTree(opNode op)
{
double temp = 0.0;
//If left and right node is constant carry out computation
if ((op.Left.GetType() == typeof(constNode) == true) && (op.Right.GetType() == typeof(constNode)))
{
constNode lConstant = (constNode)op.Left;
constNode rConstant = (constNode)op.Right;
double lvalue = lConstant.val;
double rvalue = rConstant.val;
temp = calculateChildren(op.op, lvalue, rvalue);
}
//If left node is var and right node is constant carry out computation
else if ((op.Left.GetType() == typeof(varNode) == true) && (op.Right.GetType() == typeof(constNode)))
{
varNode lConstant = (varNode)op.Left;
constNode rConstant = (constNode)op.Right;
double lvalue = m_variables[lConstant.valName];
double rvalue = rConstant.val;
temp = calculateChildren(op.op, lvalue, rvalue);
}
//If left and right are var nodes look up values in dictionary and compute
else if ((op.Left.GetType() == typeof(varNode) == true) && (op.Right.GetType() == typeof(varNode)))
{
varNode lConstant = (varNode)op.Left;
varNode rConstant = (varNode)op.Right;
double lvalue = m_variables[lConstant.valName];
double rvalue = m_variables[rConstant.valName];
temp = calculateChildren(op.op, lvalue, rvalue);
}
//if left is constant node and right is var carry out computations and neccessary steps
else if ((op.Left.GetType() == typeof(constNode) == true) && (op.Right.GetType() == typeof(varNode)))
{
constNode lConstant = (constNode)op.Left;
varNode rConstant = (varNode)op.Right;
double lvalue = lConstant.val;
double rvalue = m_variables[rConstant.valName];
temp = calculateChildren(op.op, lvalue, rvalue);
}
//get right child if its a varNode
else if((op.Left.GetType() == typeof(opNode) == true) && (op.Right.GetType() == typeof(varNode)))
{
varNode rVar = (varNode)op.Right;
double rvalue = m_variables[rVar.valName];
return temp;
}
//get right child if its a constNode
else if((op.Left.GetType() == typeof(opNode) == true) && (op.Right.GetType() == typeof(constNode)))
{
constNode rVar = (constNode)op.Right;
double rvalue = rVar.val;
temp = rvalue;
}
//Left child is a varNode while right is an opNode
else if((op.Left.GetType() == typeof(varNode)) && (op.Right.GetType() == typeof(opNode)))
{
varNode lvar = (varNode)op.Left;
double lvalue = m_variables[lvar.valName];
temp = lvalue;
}
//left child
else if((op.Left.GetType() == typeof(constNode)) && (op.Right.GetType() == typeof(opNode)))
{
constNode lvar = (constNode)op.Left;
double lvalue = lvar.val;
temp = lvalue;
}
return temp;
}
private static Node Compile(string exp, char op)
{
int counter = 0;
//Iterate through expression from right to left
for (int i = exp.Length - 1; i >= 0; i--)
{
if (')' == exp[i]) { counter++; }
else if ('(' == exp[i]) { counter--; }
if (counter == 0 && op == exp[i])
{
opNode on = new opNode() { op = exp[i] };
on.Left = Compile(exp.Substring(0, i));
on.Right = Compile(exp.Substring(i + 1));
return on;
}
}
//Throw exeception if we don't find a matching parenthesis
if (counter != 0) { throw new Exception(); }
return null;
}