internal double rEval(Node node)
{
if ((node.GetType().Equals(typeof(VariableNode))))
{
return (node as VariableNode).Value;
}
else if ((node.GetType().Equals(typeof(NumNode))))
{
return (node as NumNode).Value;
}
else if ((node.GetType().Equals(typeof(OperatorNode))))
{
if ((node as OperatorNode).value == "+")
return rEval((node as OperatorNode).left) + rEval((node as OperatorNode).right);
else if ((node as OperatorNode).value == "-")
return rEval((node as OperatorNode).left) - rEval((node as OperatorNode).right);
else if ((node as OperatorNode).value == "/")
return rEval((node as OperatorNode).left) / rEval((node as OperatorNode).right);
else if ((node as OperatorNode).value == "*")
return rEval((node as OperatorNode).left) * rEval((node as OperatorNode).right);
else
return 0;
}
else
return 0;
}
//travels through a node and evaluates the tree
//NOTE:
//this version CAN take multiple expressions,
//But does not take into account precedence of operators.
double evaluate(Node root)
{
double evaluation = 0;
if(root is opNode)
{
opNode myOp = (opNode)root;
double lv = evaluate(myOp.Left);
double rv = evaluate(myOp.Right);
if(myOp.Data == "+")
{
evaluation = lv + rv;
}
else if (myOp.Data == "-")
{
evaluation = lv - rv;
}
else if (myOp.Data == "/")
{
evaluation = lv / rv;
}
else if (myOp.Data == "*")
{
evaluation = lv * rv;
}
}
else if(root is constNode)
{
constNode myConst = (constNode)root;
evaluation = myConst.Value;
}
else if(root is varNode)
{
varNode myVar = (varNode)root;
evaluation = myVar.Value;
}
return evaluation;
}
void printTree(Node root)
{
if(root is opNode)
{
opNode myRoot = (opNode)root;
if (myRoot.Left != null)
{
Console.Write("(");
printTree(myRoot.Left);
}
Console.WriteLine(myRoot.Data);
if(myRoot.Right != null)
{
printTree(myRoot.Right);
Console.Write(")");
}
}
else
{
Console.Write(" " + root.Data + " " );
}
}
private void BuildTree()
{
string[] infix = Regex.Split(expression, @"([a-zA-Z][a-zA-Z0-9_]*)|([0-9]+)|([+-/*])|[^\s*]$"); // split expression into parts
List<string> postfix = postfixer(infix);
Stack<Node> nodeStack = new Stack<Node>();
for (int i = 0; i < postfix.Count(); i++)
{
double value;
if (Double.TryParse(postfix[i], out value)) // if is double
{
NumNode newNode = new NumNode(postfix[i]);
nodeStack.Push(newNode);
}
else if (is_operator(postfix[i])) // Operator
{
OperatorNode newNode = new OperatorNode(postfix[i]);
newNode.right = nodeStack.Pop();
newNode.left = nodeStack.Pop();
nodeStack.Push(newNode);
}
else // Variable
{
VariableNode newNode = new VariableNode(postfix[i]);
nodeStack.Push(newNode);
}
}
root = nodeStack.Pop();
}
// Implement this constructor to construct the tree from the specific expression
public ExpTree(string exp)
{
root = null;
expression = exp;
BuildTree();
}
// Implement this constructor to construct the tree from the default expression
public ExpTree()
{
root = null;
expression = "A1-12-C1";
BuildTree();
}
internal OperatorNode(string data)
: base(data)
{
left = null;
right = null;
}
private bool Search(Node next, string varName, double varValue)
{
if ((next.GetType().Equals(typeof(VariableNode))) && (next as VariableNode).value == varName)
{
(next as VariableNode).Value = varValue;
return true;
}
else if ((next.GetType().Equals(typeof(OperatorNode))))
{
Search((next as OperatorNode).left, varName, varValue);
Search((next as OperatorNode).right, varName, varValue);
}
else
{
return false;
}
return false;
}
