MonoDevelop.Gettext.StringEscaping.FromXml C# (CSharp) Method

        static string FromXml(string text)
        {
            StringBuilder sb = new StringBuilder ();
            for (int i = 0; i < text.Length; i++) {
                char c1 = text[i];
                if (c1 == '&') {
                    int end = text.IndexOf (';', i);
                    if (end == -1)
                        throw new FormatException ("Unterminated XML entity.");
                    string entity = text.Substring (i+1, end - i - 1);
                    switch (entity) {
                    case "lt":
                        sb.Append ('<');
                        break;
                    case "gt":
                        sb.Append ('>');
                        break;
                    case "amp":
                        sb.Append ('&');
                        break;
                    case "apos":
                        sb.Append ('\'');
                        break;
                    case "quot":
                        sb.Append ('"');
                        break;
                    default:
                        throw new FormatException ("Unrecogised XML entity '&" + entity + ";'.");
                    }
                    i = end;
                } else
                    sb.Append (c1);
            }
            return sb.ToString ();
        }