public object VisitUnary(Expression.Unary expression)
{
var right = Evaluate(expression.Right);
switch (expression.Operator.Type)
{
case TokenType.Minus:
CheckNumberOperand(expression.Operator, right);
return(-(double)right);
case TokenType.Bang:
return(!IsTruthy(right));
}
// unreachable.
return(null);
}
public string VisitUnary(Expression.Unary expression)
{
return(Parenthesize(expression.Operator.Lexeme, expression.Right));
}