System.Globalization.CultureTableRecord.UnescapeWin32String C# (CSharp) Method

        static private String UnescapeWin32String(String str, int start, int end)
        {
            StringBuilder result = null;

            bool inQuote = false;
            for (int i = start; i < str.Length && i <= end; i++)
            {
                // Look for quote
                if (str[i] == '\'')
                {
                    // Already in quote?
                    if (inQuote)
                    {
                        BCLDebug.Assert(result != null, "[CultureTable.UnescapeWin32String]Expect result to be non-null");
                        // See another single quote.  Is this '' of 'fred''s' or ending quote?
                        if (i + 1 < str.Length)
                        {
                            if (str[i+1] == '\'')
                            {
                                // Append a ' and keep going (so we don't turn off quote mode)
                                result.Append('\'');
                                i++;
                                continue;
                            }
                        }

                        inQuote = false;
                    }
                    else
                    {
                        // Found beginning quote, remove it.
                        inQuote = true;
                        if (result == null)
                            result = new StringBuilder(str, start, i - start, str.Length);
                    }
                }
                else
                {
                    // If we have a builder we need to add our non-quote char
                    if (result != null)
                        result.Append(str[i]);
                }
            }

            // No ', just return input string substring
            if (result == null)
                return (str.Substring(start, end-start + 1));

            // Had ', need to use the builder
            return (result.ToString());
        }