C# IXmlNode.HasChildNodes方法代码示例

        /// <summary>
        /// Performs a parsing pass over a tbody to read information about column width and rowspan attributes. Information read about width
        /// attributes is stored in the reference ArrayList parameter columnStarts, which contains a list of all starting
        /// positions of all columns in the table, ordered from left to right. Row spans are taken into consideration when 
        /// computing column starts
        /// </summary>
        /// <param name="htmlTbodyElement">
        /// XmlElement representing Html tbody whose structure is to be analyzed
        /// </param>
        /// <param name="columnStarts">
        /// ArrayList of type double which contains the function output. If analysis fails, this parameter is set to null
        /// </param>
        /// <param name="tableWidth">
        /// Current width of the table. This is used to determine if a new column when added to the end of table should
        /// come after the last column in the table or is actually splitting the last column in two. If it is only splitting
        /// the last column it should inherit row span for that column
        /// </param>
        /// <returns>
        /// Calculated width of a tbody.
        /// In case of non-analizable column width structure return 0;
        /// </returns>
        private static double AnalyzeTbodyStructure(IXmlNode htmlTbodyElement, List<double> columnStarts, List<int> activeRowSpans, double tableWidth)
        {
            // Parameter validation
            Debug.Assert(htmlTbodyElement.LocalName.ToLower() == "tbody");
            Debug.Assert(columnStarts != null);

            double tbodyWidth = 0;
            bool columnWidthsAvailable = true;

            if (!htmlTbodyElement.HasChildNodes())
            {
                return tbodyWidth;
            }

            // Set active row spans to 0 - thus ignoring row spans crossing tbody boundaries
            ClearActiveRowSpans(activeRowSpans);

            var htmlChildNode = htmlTbodyElement.FirstChild;

            // Analyze tr elements
            while (htmlChildNode != null && columnWidthsAvailable)
            {
                switch (htmlChildNode.LocalName.ToLower())
                {
                    case "tr":
                        double trWidth = AnalyzeTRStructure(htmlChildNode, columnStarts, activeRowSpans, tbodyWidth);
                        if (trWidth > tbodyWidth)
                        {
                            tbodyWidth = trWidth;
                        }
                        break;
                    case "td":
                        columnWidthsAvailable = false; // interrupt the analisys
                        break;
                    default:
                        break;
                }

                htmlChildNode = htmlChildNode.NextSibling;
            }

            // Set active row spans to 0 - thus ignoring row spans crossing tbody boundaries
            ClearActiveRowSpans(activeRowSpans);

            return columnWidthsAvailable ? tbodyWidth : 0;
        }

        /// <summary>
        /// Performs a parsing pass over a tr element to read information about column width and rowspan attributes.  
        /// </summary>
        /// <param name="htmlTRElement">
        /// XmlElement representing Html tr element whose structure is to be analyzed
        /// </param>
        /// <param name="columnStarts">
        /// ArrayList of type double which contains the function output. If analysis is successful, this ArrayList contains
        /// all the points which are the starting position of any column in the tr, ordered from left to right. If analysis fails,
        /// the ArrayList is set to null
        /// </param>
        /// <param name="activeRowSpans">
        /// ArrayList representing all columns currently spanned by an earlier row span attribute. These columns should
        /// not be used for data in this row. The ArrayList actually contains notation for all columns in the table, if the
        /// active row span is set to 0 that column is not presently spanned but if it is > 0 the column is presently spanned
        /// </param>
        /// <param name="tableWidth">
        /// Double value representing the current width of the table.
        /// Return 0 if analisys was insuccessful.
        /// </param>
        private static double AnalyzeTRStructure(IXmlNode htmlTRElement, List<double> columnStarts, List<int> activeRowSpans, double tableWidth)
        {
            double columnWidth;

            // Parameter validation
            Debug.Assert(htmlTRElement.LocalName.ToLower() == "tr");
            Debug.Assert(columnStarts != null);
            Debug.Assert(activeRowSpans != null);
            Debug.Assert(columnStarts.Count == activeRowSpans.Count);

            if (!htmlTRElement.HasChildNodes())
            {
                return 0;
            }

            bool columnWidthsAvailable = true;

            double columnStart = 0; // starting position of current column
            var htmlChildNode = htmlTRElement.FirstChild;
            int columnIndex = 0;
            double trWidth = 0;

            // Skip spanned columns to get to real column start
            if (columnIndex < activeRowSpans.Count)
            {
                Debug.Assert((double)columnStarts[columnIndex] >= columnStart);
                if ((double)columnStarts[columnIndex] == columnStart)
                {
                    // The new column may be in a spanned area
                    while (columnIndex < activeRowSpans.Count && (int)activeRowSpans[columnIndex] > 0)
                    {
                        activeRowSpans[columnIndex] = (int)activeRowSpans[columnIndex] - 1;
                        Debug.Assert((int)activeRowSpans[columnIndex] >= 0);
                        columnIndex++;
                        columnStart = (double)columnStarts[columnIndex];
                    }
                }
            }

            while (htmlChildNode != null && columnWidthsAvailable)
            {
                Debug.Assert(columnStarts.Count == activeRowSpans.Count);

                VerifyColumnStartsAscendingOrder(columnStarts);

                switch (htmlChildNode.LocalName.ToLower())
                {
                    case "td":
                        Debug.Assert(columnIndex <= columnStarts.Count);
                        if (columnIndex < columnStarts.Count)
                        {
                            Debug.Assert(columnStart <= (double)columnStarts[columnIndex]);
                            if (columnStart < (double)columnStarts[columnIndex])
                            {
                                columnStarts.Insert(columnIndex, columnStart);
                                // There can be no row spans now - the column data will appear here
                                // Row spans may appear only during the column analysis
                                activeRowSpans.Insert(columnIndex, 0);
                            }
                        }
                        else
                        {
                            // Column start is greater than all previous starts. Row span must still be 0 because
                            // we are either adding after another column of the same row, in which case it should not inherit
                            // the previous column's span. Otherwise we are adding after the last column of some previous
                            // row, and assuming the table widths line up, we should not be spanned by it. If there is
                            // an incorrect tbale structure where a columns starts in the middle of a row span, we do not
                            // guarantee correct output
                            columnStarts.Add(columnStart);
                            activeRowSpans.Add(0);
                        }
                        columnWidth = GetColumnWidth(htmlChildNode);
                        if (columnWidth != -1)
                        {
                            int nextColumnIndex;
                            int rowSpan = GetRowSpan(htmlChildNode);

                            nextColumnIndex = GetNextColumnIndex(columnIndex, columnWidth, columnStarts, activeRowSpans);
                            if (nextColumnIndex != -1)
                            {
//.........这里部分代码省略.........

        /// <summary>
        /// Performs a parsing pass over a table to read information about column width and rowspan attributes. This information
        /// is used to determine the starting point of each column. 
        /// </summary>
        /// <param name="htmlTableElement">
        /// XmlElement representing Html table whose structure is to be analyzed
        /// </param>
        /// <returns>
        /// ArrayList of type double which contains the function output. If analysis is successful, this ArrayList contains
        /// all the points which are the starting position of any column in the table, ordered from left to right.
        /// In case if analisys was impossible we return null.
        /// </returns>
        private static List<double> AnalyzeTableStructure(IXmlNode htmlTableElement)
        {
            // Parameter validation
            Debug.Assert(htmlTableElement.LocalName.ToLower() == "table");

            if (!htmlTableElement.HasChildNodes())
            {
                return null;
            }

            bool columnWidthsAvailable = true;

            var columnStarts = new List<double>();
            var activeRowSpans = new List<int>();

            Debug.Assert(columnStarts.Count == activeRowSpans.Count);

            var htmlChildNode = htmlTableElement.FirstChild;

            double tableWidth = 0;  // Keep track of table width which is the width of its widest row

            // Analyze tbody and tr elements
            while (htmlChildNode != null && columnWidthsAvailable)
            {
                Debug.Assert(columnStarts.Count == activeRowSpans.Count);

                switch (htmlChildNode.LocalName.ToLower())
                {
                    case "tbody":
                        // Tbody element, we should analyze its children for trows
                        double tbodyWidth = AnalyzeTbodyStructure(htmlChildNode, columnStarts, activeRowSpans, tableWidth);
                        if (tbodyWidth > tableWidth)
                        {
                            // Table width must be increased to supported newly added wide row
                            tableWidth = tbodyWidth;
                        }
                        else if (tbodyWidth == 0)
                        {
                            // Tbody analysis may return 0, probably due to unprocessable format.
                            // We should also fail.
                            columnWidthsAvailable = false; // interrupt the analisys
                        }
                        break;
                    case "tr":
                        // Table row. Analyze column structure within row directly
                        double trWidth = AnalyzeTRStructure(htmlChildNode, columnStarts, activeRowSpans, tableWidth);
                        if (trWidth > tableWidth)
                        {
                            tableWidth = trWidth;
                        }
                        else if (trWidth == 0)
                        {
                            columnWidthsAvailable = false; // interrupt the analisys
                        }
                        break;
                    case "td":
                        // Incorrect formatting, too deep to analyze at this level. Return null.
                        // TODO: implement analysis at this level, possibly by creating a new tr
                        columnWidthsAvailable = false; // interrupt the analisys
                        break;
                    default:
                        // Element should not occur directly in table. Ignore it.
                        break;
                }

                htmlChildNode = htmlChildNode.NextSibling;
            }

            if (columnWidthsAvailable)
            {
                // Add an item for whole table width
                columnStarts.Add(tableWidth);
                VerifyColumnStartsAscendingOrder(columnStarts);
            }
            else
            {
                columnStarts = null;
            }

            return columnStarts;
        }