/// <summary>
/// Name:Evaluate
/// Description:Evaluates the expression tree
/// </summary>
/// <param name="node">inputed node of the expression tree</param>
/// <returns>returns a double of the evaluated expression</returns>
private double Evaluate(BasicNode node)
{
ConstantNode constnode = node as ConstantNode;
if (constnode != null)
{
return(constnode.OperatorValue);
}
VariableNode varnode = node as VariableNode;
if (varnode != null)
{
// used to be a try/catch, but now we set every new variable to 0 when the tree is made, so there will always be a value to obtain.
return(this.variables[varnode.Name]);
}
OperatorNode opnode = node as OperatorNode;
if (opnode != null)
{
return(opnode.Evaluate(this.Evaluate(opnode.Left), this.Evaluate(opnode.Right)));
}
return(0);
}
/// <summary>
/// Name:Evaluate
/// Description:Evaluates the expression tree
/// </summary>
/// <param name="node">inputed node of the expression tree</param>
/// <returns>returns a double of the evaluated expression</returns>
private double Evaluate(BasicNode node)
{
if (node != null && node is OperatorNode)
{
OperatorNode temp = (OperatorNode)node;
return(temp.Evaluate(this.Evaluate(temp.Left), this.Evaluate(temp.Right)));
}
if (node != null && node is VariableNode)
{
try
{
return(this.variables[node.Name]);
}
catch
{
throw new System.ArgumentException("Variable " + node.Name + " has not been defined.", "Variable Not Defined");
}
}
if (node != null && node is ConstantNode)
{
ConstantNode temp = (ConstantNode)node;
return(temp.OperatorValue);
}
return(0);
}
/// <summary>
/// Name:Compile
/// Description:Compiles the expression
/// </summary>
/// <param name="expression">inputed expression</param>
/// <returns>returns the basenode of the expression tree</returns>
private static BasicNode Compile(string expression)
{
if (expression.Length != 0)
{
int operatorIndex = expression.Length - 1;
while (operatorIndex > 0 && !ExpressionTreeFactory.IsValidOperator(expression[operatorIndex]))
{
operatorIndex--;
}
if (ExpressionTreeFactory.IsValidOperator(expression[operatorIndex]))
{
OperatorNode newNode = ExpressionTreeFactory.CreateOperatorNode(expression[operatorIndex]);
newNode.Left = Compile(expression.Substring(0, operatorIndex));
newNode.Right = Compile(expression.Substring(operatorIndex + 1));
return(newNode);
}
double number;
if (double.TryParse(expression, out number))
{
ConstantNode newNode = new ConstantNode(number);
return(newNode);
}
else
{
VariableNode newNode = new VariableNode(expression);
return(newNode);
}
}
return(null);
}
/// <summary>
/// Name:Compile
/// Description:Compiles the expression
/// </summary>
/// <param name="expression">inputed expression</param>
/// <returns>returns the basenode of the expression tree</returns>
private BasicNode Compile(string expression)
{
expression = expression.Replace(" ", string.Empty);
int counter = 1, i = 0;
if (expression[i] == '(')
{
for (i = 1; expression.Length > i; i++)
{
if (expression[i] == '(')
{
counter++;
}
else if (expression[i] == ')')
{
counter--;
if (counter == 0)
{
if (i == expression.Length - 1)
{
return(this.Compile(expression.Substring(1, expression.Length - 2)));
}
break;
}
}
}
if (counter != 0)
{
throw new System.ArgumentException("Too many or too few parentheses", "Invalid Expression");
}
}
int index = GetLowestOperatorInheritanceIndex(expression);
if (index != -1)
{
OperatorNode node = ExpressionTreeFactory.CreateOperatorNode(expression[index]);
node.Right = this.Compile(expression.Substring(index + 1));
node.Left = this.Compile(expression.Substring(0, index));
return(node);
}
else if (index == -2)
{
throw new System.ArgumentException("Too many or too few parentheses", "Invalid Expression");
}
return(this.BuildVNode(expression));
}
