private object EvaluateExpression(SemanticExpression node)
{
//Convert the semantic representation into a concrete one
switch (node)
{
case SemanticLiteralExpression n:
return(n.Value);
case SemanticVariableExpression v:
return(_variables[v.Variable]);
case SemanticAssignmentExpression a:
{
var value = EvaluateExpression(a.Expression);
_variables[a.Variable] = value;
return(value);
}
case SemanticUnaryExpression u:
{
var operand = EvaluateExpression(u.Operand);
return(u.Operator.Kind switch
{
SemanticUnaryOperatorKind.Identity => (object)(int)operand,
SemanticUnaryOperatorKind.Negative => (-1 * (int)operand),
SemanticUnaryOperatorKind.LogicalNegation => !(bool)operand,
SemanticUnaryOperatorKind.BitwiseNegation => ~(int)operand,
_ => throw new Exception($"Unexpected unary operator {u.Operator.Kind}")
});
}
public Evaluator(SemanticExpression root, Dictionary <VariableSymbol, object> variables)
{
_root = root;
_variables = variables;
}
