System.Text.RegularExpressions.RegexParser.OptionFromCode C# (CSharp) Method

        internal static RegexOptions OptionFromCode(char ch)
        {
            // case-insensitive
            if (ch >= 'A' && ch <= 'Z')
                ch += (char)('a' - 'A');

            switch (ch)
            {
                case 'i':
                    return RegexOptions.IgnoreCase;
                case 'r':
                    return RegexOptions.RightToLeft;
                case 'm':
                    return RegexOptions.Multiline;
                case 'n':
                    return RegexOptions.ExplicitCapture;
                case 's':
                    return RegexOptions.Singleline;
                case 'x':
                    return RegexOptions.IgnorePatternWhitespace;
            #if DEBUG
                case 'd':
                    return RegexOptions.Debug;
            #endif
                case 'e':
                    return RegexOptions.ECMAScript;
                default:
                    return 0;
            }
        }