System.Net.Http.Headers.Lexer.IsValidToken C# (CSharp) Method

		public static bool IsValidToken (string input)
		{
			int i = 0;
			//
			// any CHAR except CTLs or separator
			//
			for (; i < input.Length; ++i) {
				char s = input[i];
				if (!IsValidCharacter (s))
					return false;
			}

			return i > 0;
		}

        static string EncodeBase64Value(string value)
        {
            bool quoted = value.Length > 1 && value [0] == '"' && value [value.Length - 1] == '"';

            if (quoted)
            {
                value = value.Substring(1, value.Length - 2);
            }

            for (int i = 0; i < value.Length; ++i)
            {
                var ch = value[i];
                if (ch > 127)
                {
                    var encoding = Encoding.UTF8;
                    return(string.Format("\"=?{0}?B?{1}?=\"",
                                         encoding.WebName, Convert.ToBase64String(encoding.GetBytes(value))));
                }
            }

            if (quoted || !Lexer.IsValidToken(value))
            {
                return("\"" + value + "\"");
            }

            return(value);
        }