System.Data.ExprException.InvalidPattern C# (CSharp) Method

        public static Exception InvalidPattern(string pat)
        {
            return _Eval(SR.Format(SR.Expr_InvalidPattern, pat));
        }

        internal string AnalyzePattern(string pat)
        {
            int length = pat.Length;

            char[] destination = new char[length + 1];
            pat.CopyTo(0, destination, 0, length);
            destination[length] = '\0';
            string str = null;

            char[] chArray2 = new char[length + 1];
            int    num3     = 0;
            int    num4     = 0;
            int    index    = 0;

            while (index < length)
            {
                if ((destination[index] == '*') || (destination[index] == '%'))
                {
                    while (((destination[index] == '*') || (destination[index] == '%')) && (index < length))
                    {
                        index++;
                    }
                    if (((index < length) && (num3 > 0)) || (num4 >= 2))
                    {
                        throw ExprException.InvalidPattern(pat);
                    }
                    num4++;
                }
                else if (destination[index] == '[')
                {
                    index++;
                    if (index >= length)
                    {
                        throw ExprException.InvalidPattern(pat);
                    }
                    chArray2[num3++] = destination[index++];
                    if (index >= length)
                    {
                        throw ExprException.InvalidPattern(pat);
                    }
                    if (destination[index] != ']')
                    {
                        throw ExprException.InvalidPattern(pat);
                    }
                    index++;
                }
                else
                {
                    chArray2[num3++] = destination[index];
                    index++;
                }
            }
            str = new string(chArray2, 0, num3);
            if (num4 == 0)
            {
                this.kind = 4;
                return(str);
            }
            if (num3 > 0)
            {
                if ((destination[0] == '*') || (destination[0] == '%'))
                {
                    if ((destination[length - 1] == '*') || (destination[length - 1] == '%'))
                    {
                        this.kind = 3;
                        return(str);
                    }
                    this.kind = 2;
                    return(str);
                }
                this.kind = 1;
                return(str);
            }
            this.kind = 5;
            return(str);
        }