BF2Statistics.Gamespy.MasterClient.IsLogical C# (CSharp) Method

        private static bool IsLogical(string filter, int i, out int length, bool previous = false)
        {
            bool isLogical = false;
            length = 0;

            if (i < filter.Length - 2)
            {
                string op = filter.Substring(i - (i >= 3 ? (previous ? 3 : 0) : 0), 2);
                if (op == "&&" || op == "||" || op.Equals("or", StringComparison.InvariantCultureIgnoreCase))
                {
                    isLogical = true;
                    length = 2;
                }
            }

            if (!isLogical)
            {
                if (i < filter.Length - 3)
                {
                    string op = filter.Substring(i - (i >= 4 ? (previous ? 4 : 0) : 0), 3);
                    if (op.Equals("and", StringComparison.InvariantCultureIgnoreCase))
                    {
                        isLogical = true;
                        length = 3;
                    }
                }
            }

            return isLogical;
        }