/// <summary>
        /// Marks characters from the specified languages as safe.
        /// </summary>
        /// <param name="lowerCodeCharts">The combination of lower code charts to use.</param>
        /// <param name="lowerMidCodeCharts">The combination of lower mid code charts to use.</param>
        /// <param name="midCodeCharts">The combination of mid code charts to use.</param>
        /// <param name="upperMidCodeCharts">The combination of upper mid code charts to use.</param>
        /// <param name="upperCodeCharts">The combination of upper code charts to use.</param>
        /// <remarks>The safe list affects all HTML and XML encoding functions.</remarks>
        public static void MarkAsSafe(
            LowerCodeCharts lowerCodeCharts,
            LowerMidCodeCharts lowerMidCodeCharts,
            MidCodeCharts midCodeCharts,
            UpperMidCodeCharts upperMidCodeCharts,
            UpperCodeCharts upperCodeCharts)
        {
            if (lowerCodeCharts == currentLowerCodeChartSettings &&
                lowerMidCodeCharts == currentLowerMidCodeChartSettings &&
                midCodeCharts == currentMidCodeChartSettings &&
                upperMidCodeCharts == currentUpperMidCodeChartSettings &&
                upperCodeCharts == currentUpperCodeChartSettings)
            {
                return;
            }

            AcquireWriteLock();
            try
            {
                // Reset back to everything hashed.
                characterValues = SafeList.Generate(65536, SafeList.HashThenValueGenerator);

                SafeList.PunchUnicodeThrough(
                    ref characterValues,
                    lowerCodeCharts,
                    lowerMidCodeCharts,
                    midCodeCharts,
                    upperMidCodeCharts,
                    upperCodeCharts);

                ApplyHtmlSpecificValues();

                currentLowerCodeChartSettings    = lowerCodeCharts;
                currentLowerMidCodeChartSettings = lowerMidCodeCharts;
                currentMidCodeChartSettings      = midCodeCharts;
                currentUpperMidCodeChartSettings = upperMidCodeCharts;
                currentUpperCodeChartSettings    = upperCodeCharts;
            }
            finally
            {
                ReleaseWriteLock();
            }
        }
 /// <summary>
 /// Initializes the HTML safe list.
 /// </summary>
 private static void InitialiseSafeList()
 {
     AcquireWriteLock();
     try
     {
         if (characterValues == null)
         {
             // We use decimal encoding to support some older Japanese mobile browsers which don't support hex encoding.
             characterValues = SafeList.Generate(0xFFFF, SafeList.HashThenValueGenerator);
             SafeList.PunchUnicodeThrough(
                 ref characterValues,
                 currentLowerCodeChartSettings,
                 currentLowerMidCodeChartSettings,
                 currentMidCodeChartSettings,
                 currentUpperMidCodeChartSettings,
                 currentUpperCodeChartSettings);
             ApplyHtmlSpecificValues();
         }
     }
     finally
     {
         ReleaseWriteLock();
     }
 }
        /// <summary>
        /// Encodes input strings for use in HTML.
        /// </summary>
        /// <param name="input">String to be encoded</param>
        /// <param name="useNamedEntities">Value indicating if the HTML 4.0 named entities should be used.</param>
        /// <param name="encoderTweak">A <see cref="MethodSpecificEncoder"/> function, if needed.</param>
        /// <returns>
        /// Encoded string for use in HTML.
        /// </returns>
        private static string HtmlEncode(string input, bool useNamedEntities, MethodSpecificEncoder encoderTweak)
        {
            if (string.IsNullOrEmpty(input))
            {
                return(input);
            }

            if (characterValues == null)
            {
                InitialiseSafeList();
            }

            char[][] namedEntities = null;
            if (useNamedEntities)
            {
                namedEntities = namedEntitiesLazy.Value;
            }

            // Setup a new StringBuilder for output.
            // Worse case scenario - the longest entity name, thetasym is 10 characters, including the & and ;.
            StringBuilder builder = EncoderUtil.GetOutputStringBuilder(input.Length, 10);

            AcquireReadLock();
            try
            {
                Utf16StringReader stringReader = new Utf16StringReader(input);
                while (true)
                {
                    int currentCodePoint = stringReader.ReadNextScalarValue();
                    if (currentCodePoint < 0)
                    {
                        break; // EOF
                    }

                    if (currentCodePoint > char.MaxValue)
                    {
                        // We don't have a pre-generated mapping of characters beyond the Basic Multilingual
                        // Plane (BMP), so we need to generate these encodings on-the-fly. We should encode
                        // the code point rather than the surrogate code units that make up this code point.
                        // See: http://www.w3.org/International/questions/qa-escapes#bytheway
                        char[] encodedCharacter = SafeList.HashThenValueGenerator(currentCodePoint);
                        builder.Append('&');
                        builder.Append(encodedCharacter);
                        builder.Append(';');
                    }
                    else
                    {
                        // If we reached this point, the code point is within the BMP.
                        char   currentCharacter = (char)currentCodePoint;
                        char[] tweekedValue;

                        if (encoderTweak != null && encoderTweak(currentCharacter, out tweekedValue))
                        {
                            builder.Append(tweekedValue);
                        }
                        else if (useNamedEntities && namedEntities[currentCodePoint] != null)
                        {
                            char[] encodedCharacter = namedEntities[currentCodePoint];
                            builder.Append('&');
                            builder.Append(encodedCharacter);
                            builder.Append(';');
                        }
                        else if (characterValues[currentCodePoint] != null)
                        {
                            // character needs to be encoded
                            char[] encodedCharacter = characterValues[currentCodePoint];
                            builder.Append('&');
                            builder.Append(encodedCharacter);
                            builder.Append(';');
                        }
                        else
                        {
                            // character does not need encoding
                            builder.Append(currentCharacter);
                        }
                    }
                }
            }
            finally
            {
                ReleaseReadLock();
            }

            return(builder.ToString());
        }