public double Eval(Binding bind)
{
Bind = bind;
LanguageTreeNode tempNode = root;
return(_Eval(tempNode));
}
/*
* We need to set the number value to double type before we eval the tree
*/
private double _Eval(LanguageTreeNode root)
{
if (root == null)
{
return(0);
}
else
{
if (root.value.GetType() == typeof(double))
{
return((double)root.value);
}
else if (root.value.GetType() == typeof(char))
{
switch (root.value)
{
case '+':
return(_Eval(root.left) + _Eval(root.right));
case '*':
return(_Eval(root.left) * _Eval(root.right));
case '-':
return(_Eval(root.left) - _Eval(root.right));
case '/':
return(_Eval(root.left) / _Eval(root.right));
case '^':
{
// a ^ b
var a = _Eval(root.left);
var b = _Eval(root.right);
return(Math.Pow(a, b));
}
case '=':
return(Convert.ToDouble(_Eval(root.left) == _Eval(root.right)));
case '@':
{
/*
* df/dx
*/
const double deltaX = 0.000000001;
Binding xAndDeltaX = new Binding();
xAndDeltaX.SetBind(Bind.GetMagic(), Bind.GetBind(Bind.GetMagic()) + deltaX);
var f_x = _Eval(root.left);
var temp = Bind;
Bind = xAndDeltaX;
var f_xAndDeltaX = _Eval(root.left);
Bind = temp;
return((f_xAndDeltaX - f_x) / deltaX);
}
default:
throw new FormatException($"{ErrMessage}unknown operator");
}
}
else if (root.value.GetType() == typeof(string))
{
string valueOfRoot = (string)root.value;
if (Bind.Contain(valueOfRoot))
{
return(Bind.GetBind(valueOfRoot));
}
else
{
throw new FormatException($"{ErrMessage}unbind symbol : {valueOfRoot}");
}
}
else
{
throw new FormatException($"{ErrMessage}unknown value type : {root.value}");
}
}
}
public SolverLanguageTree(object value, LanguageTreeNode left, LanguageTreeNode right)
{
root = new LanguageTreeNode(value, left, right);
}
public LanguageTreeNode(Object value, LanguageTreeNode left, LanguageTreeNode right)
{
this.value = value;
this.left = left;
this.right = right;
}
