public override bool Equals(object obj)
        {
            if (obj == null)
            {
                return(false);
            }

            SQLiteUnaryExpression dst = obj as SQLiteUnaryExpression;

            if (dst == null)
            {
                return(false);
            }

            if (!RefCompare.Compare(_expr, dst._expr))
            {
                return(false);
            }
            if (_op != dst._op)
            {
                return(false);
            }

            return(base.Equals(obj));
        }
        public override object Clone()
        {
            SQLiteExpression expr = null;

            if (_expr != null)
            {
                expr = (SQLiteExpression)_expr.Clone();
            }

            SQLiteUnaryExpression res = new SQLiteUnaryExpression();

            res._expr = expr;
            res._op   = _op;
            return(res);
        }