While.Parsing.Parser.ExpectBool C# (CSharp) Метод

        private bool ExpectBool(Expression exp, Token t, bool isRightHandSide)
        {
            if (!(exp is TypedExpression<bool>)) {
                errors.SemErr(t.line, t.col, string.Format("'{0}' expects a boolean expression on its {1} side", t.val, isRightHandSide ? "right" : "left"));
                return false;
            }
            return true;
        }