System.Text.RegularExpressions.RegexInterpreter.Refmatch C# (CSharp) Method

        private bool Refmatch(int index, int len)
        {
            int c;
            int pos;
            int cmpos;

            if (!_rightToLeft)
            {
                if (runtextend - runtextpos < len)
                    return false;

                pos = runtextpos + len;
            }
            else
            {
                if (runtextpos - runtextbeg < len)
                    return false;

                pos = runtextpos;
            }
            cmpos = index + len;

            c = len;

            if (!_caseInsensitive)
            {
                while (c-- != 0)
                    if (runtext[--cmpos] != runtext[--pos])
                        return false;
            }
            else
            {
                while (c-- != 0)
                    if (_culture.TextInfo.ToLower(runtext[--cmpos]) != _culture.TextInfo.ToLower(runtext[--pos]))
                        return false;
            }

            if (!_rightToLeft)
            {
                pos += len;
            }

            runtextpos = pos;

            return true;
        }