public Evaluator(Bound_Expression_Node root_node)
{
_root_node = root_node;
}
private object Evaluate_Expression(Bound_Expression_Node node)
{
if (node is Bound_Literal_Expression_Node n)
{
return(n.Value);
}
if (node is Bound_Unary_Expression_Node u)
{
var operand = Evaluate_Expression(u.Operand);
switch (u.Op.Kind)
{
case Bound_Unary_Operator_Kind.Identity:
return((int)operand);
case Bound_Unary_Operator_Kind.Negation:
return(-(int)operand);
case Bound_Unary_Operator_Kind.Logical_Negation:
return(!(bool)operand);
default:
throw new Exception($"Unexpected unary operator {u.Op}");
}
}
if (node is Bound_Binary_Expression_Node b)
{
var left = Evaluate_Expression(b.Left);
var right = Evaluate_Expression(b.Right);
switch (b.Op.Kind)
{
case Bound_Binary_Operator_Kind.Addition:
return((int)left + (int)right);
case Bound_Binary_Operator_Kind.Subtraction:
return((int)left - (int)right);
case Bound_Binary_Operator_Kind.Multiplication:
return((int)left * (int)right);
case Bound_Binary_Operator_Kind.Division:
return((int)left / (int)right);
case Bound_Binary_Operator_Kind.Logical_And:
return((bool)left && (bool)right);
case Bound_Binary_Operator_Kind.Logical_Or:
return((bool)left || (bool)right);
case Bound_Binary_Operator_Kind.Equals:
return(Equals(left, right));
case Bound_Binary_Operator_Kind.Not_Equals:
return(!Equals(left, right));
default:
throw new Exception($"Unexpected binary operator {b.Op}");
}
}
throw new Exception($"Invalid Node {node.Kind}");
}
public Evaluator(Bound_Expression_Node root_node, Dictionary <string, object> variables)
{
_root_node = root_node;
_variables = variables;
}
