Optimize PipeTable parsing: O(n²) → O(n) for 3.7x–85x speedup, enables 10K+ row tables (#922)

* Optimize PipeTable parsing: O(n²) → O(n) for large tables

Pipe tables were creating deeply nested tree structures where each pipe
delimiter contained all subsequent content as children, causing O(n²)
traversal complexity for n cells. This change restructures the parser to
use a flat sibling-based structure, treating tables as matrices rather
than nested trees.

Key changes:
- Set IsClosed=true on PipeTableDelimiterInline to prevent nesting
- Add PromoteNestedPipesToRootLevel() to flatten pipes nested in emphasis
- Update cell boundary detection to use sibling traversal
- Move EmphasisInlineParser before PipeTableParser in processing order
- Fix EmphasisInlineParser to continue past IsClosed delimiters
- Add ContainsParentOrSiblingOfType<T>() helper for flat structure detection

Performance improvements (measured on typical markdown content):

| Rows | Before    | After   | Speedup |
|------|-----------|---------|---------|
| 100  | 542 μs    | 150 μs  | 3.6x    |
| 500  | 23,018 μs | 763 μs  | 30x     |
| 1000 | 89,418 μs | 1,596 μs| 56x     |
| 1500 | 201,593 μs| 2,740 μs| 74x     |
| 5000 | CRASH     | 10,588 μs| ∞      |
| 10000| CRASH     | 18,551 μs| ∞      |

Tables with 5000+ rows previously crashed due to stack overflow from
recursive depth. They now parse successfully with linear time complexity.

* remove baseline results file

* Do not use System.Index and fix nullabillity checks for older platforms

.gitignore

@@ -8,6 +8,8 @@
 *.sln.docstates
 *.nuget.props
 *.nuget.targets
+src/.idea
+BenchmarkDotNet.Artifacts
 
 # User-specific files (MonoDevelop/Xamarin Studio)
 *.userprefs

src/Markdig.Benchmarks/PipeTable/PipeTableBenchmark.cs

@@ -0,0 +1,81 @@
+// Copyright (c) Alexandre Mutel. All rights reserved.
+// This file is licensed under the BSD-Clause 2 license.
+// See the license.txt file in the project root for more information.
+
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Diagnosers;
+using Markdig;
+
+namespace Testamina.Markdig.Benchmarks.PipeTable;
+
+/// <summary>
+/// Benchmark for pipe table parsing performance, especially for large tables.
+/// Tests the performance of PipeTableParser with varying table sizes.
+/// </summary>
+[MemoryDiagnoser]
+[GcServer(true)] // Use server GC to get more comprehensive GC stats
+public class PipeTableBenchmark
+{
+    private string _100Rows = null!;
+    private string _500Rows = null!;
+    private string _1000Rows = null!;
+    private string _1500Rows = null!;
+    private string _5000Rows = null!;
+    private string _10000Rows = null!;
+    private MarkdownPipeline _pipeline = null!;
+
+    [GlobalSetup]
+    public void Setup()
+    {
+        // Pipeline with pipe tables enabled (part of advanced extensions)
+        _pipeline = new MarkdownPipelineBuilder()
+            .UseAdvancedExtensions()
+            .Build();
+
+        // Generate tables of various sizes
+        // Note: Before optimization, 5000+ rows hit depth limit due to nested tree structure.
+        // After optimization, these should work.
+        _100Rows = PipeTableGenerator.Generate(rows: 100, columns: 5);
+        _500Rows = PipeTableGenerator.Generate(rows: 500, columns: 5);
+        _1000Rows = PipeTableGenerator.Generate(rows: 1000, columns: 5);
+        _1500Rows = PipeTableGenerator.Generate(rows: 1500, columns: 5);
+        _5000Rows = PipeTableGenerator.Generate(rows: 5000, columns: 5);
+        _10000Rows = PipeTableGenerator.Generate(rows: 10000, columns: 5);
+    }
+
+    [Benchmark(Description = "PipeTable 100 rows x 5 cols")]
+    public string Parse100Rows()
+    {
+        return Markdown.ToHtml(_100Rows, _pipeline);
+    }
+
+    [Benchmark(Description = "PipeTable 500 rows x 5 cols")]
+    public string Parse500Rows()
+    {
+        return Markdown.ToHtml(_500Rows, _pipeline);
+    }
+
+    [Benchmark(Description = "PipeTable 1000 rows x 5 cols")]
+    public string Parse1000Rows()
+    {
+        return Markdown.ToHtml(_1000Rows, _pipeline);
+    }
+
+    [Benchmark(Description = "PipeTable 1500 rows x 5 cols")]
+    public string Parse1500Rows()
+    {
+        return Markdown.ToHtml(_1500Rows, _pipeline);
+    }
+
+    [Benchmark(Description = "PipeTable 5000 rows x 5 cols")]
+    public string Parse5000Rows()
+    {
+        return Markdown.ToHtml(_5000Rows, _pipeline);
+    }
+
+    [Benchmark(Description = "PipeTable 10000 rows x 5 cols")]
+    public string Parse10000Rows()
+    {
+        return Markdown.ToHtml(_10000Rows, _pipeline);
+    }
+}

src/Markdig.Benchmarks/PipeTable/PipeTableGenerator.cs

@@ -0,0 +1,61 @@
+// Copyright (c) Alexandre Mutel. All rights reserved.
+// This file is licensed under the BSD-Clause 2 license.
+// See the license.txt file in the project root for more information.
+
+using System.Text;
+
+namespace Testamina.Markdig.Benchmarks.PipeTable;
+
+/// <summary>
+/// Generates pipe table markdown content for benchmarking purposes.
+/// </summary>
+public static class PipeTableGenerator
+{
+    private const int DefaultCellWidth = 10;
+
+    /// <summary>
+    /// Generates a pipe table in markdown format.
+    /// </summary>
+    /// <param name="rows">Number of data rows (excluding header)</param>
+    /// <param name="columns">Number of columns</param>
+    /// <param name="cellWidth">Width of each cell content (default: 10)</param>
+    /// <returns>Pipe table markdown string</returns>
+    public static string Generate(int rows, int columns, int cellWidth = DefaultCellWidth)
+    {
+        var sb = new StringBuilder();
+
+        // Header row
+        sb.Append('|');
+        for (int col = 0; col < columns; col++)
+        {
+            sb.Append(' ');
+            sb.Append($"Header {col + 1}".PadRight(cellWidth));
+            sb.Append(" |");
+        }
+        sb.AppendLine();
+
+        // Separator row (with dashes)
+        sb.Append('|');
+        for (int col = 0; col < columns; col++)
+        {
+            sb.Append(new string('-', cellWidth + 2));
+            sb.Append('|');
+        }
+        sb.AppendLine();
+
+        // Data rows
+        for (int row = 0; row < rows; row++)
+        {
+            sb.Append('|');
+            for (int col = 0; col < columns; col++)
+            {
+                sb.Append(' ');
+                sb.Append($"R{row + 1}C{col + 1}".PadRight(cellWidth));
+                sb.Append(" |");
+            }
+            sb.AppendLine();
+        }
+
+        return sb.ToString();
+    }
+}

src/Markdig.Benchmarks/Program.cs

@@ -7,6 +7,7 @@ using BenchmarkDotNet.Configs;
 using BenchmarkDotNet.Running;
 
 using Markdig;
+using Testamina.Markdig.Benchmarks.PipeTable;
 
 
 namespace Testamina.Markdig.Benchmarks;
@@ -68,7 +69,16 @@ public class Program
         //config.Add(gcDiagnoser);
 
         //var  config = DefaultConfig.Instance;
-        BenchmarkRunner.Run<Program>(config);
+
+        // Run specific benchmarks based on command line arguments
+        if (args.Length > 0 && args[0] == "--pipetable")
+        {
+            BenchmarkRunner.Run<PipeTableBenchmark>(config);
+        }
+        else
+        {
+            BenchmarkRunner.Run<Program>(config);
+        }
         //BenchmarkRunner.Run<TestDictionary>(config);
         //BenchmarkRunner.Run<TestMatchPerf>();
         //BenchmarkRunner.Run<TestStringPerf>();

src/Markdig/Extensions/Tables/PipeTableExtension.cs

@@ -38,7 +38,7 @@ public class PipeTableExtension : IMarkdownExtension
         var lineBreakParser = pipeline.InlineParsers.FindExact<LineBreakInlineParser>();
         if (!pipeline.InlineParsers.Contains<PipeTableParser>())
         {
-            pipeline.InlineParsers.InsertBefore<EmphasisInlineParser>(new PipeTableParser(lineBreakParser!, Options));
+            pipeline.InlineParsers.InsertAfter<EmphasisInlineParser>(new PipeTableParser(lineBreakParser!, Options));
         }
     }
 

src/Markdig/Extensions/Tables/PipeTableParser.cs

@@ -19,7 +19,7 @@ namespace Markdig.Extensions.Tables;
 /// <seealso cref="IPostInlineProcessor" />
 public class PipeTableParser : InlineParser, IPostInlineProcessor
 {
-    private readonly LineBreakInlineParser lineBreakParser;
+    private readonly LineBreakInlineParser _lineBreakParser;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="PipeTableParser" /> class.
@@ -28,7 +28,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
     /// <param name="options">The options.</param>
     public PipeTableParser(LineBreakInlineParser lineBreakParser, PipeTableOptions? options = null)
     {
-        this.lineBreakParser = lineBreakParser ?? throw new ArgumentNullException(nameof(lineBreakParser));
+        _lineBreakParser = lineBreakParser ?? throw new ArgumentNullException(nameof(lineBreakParser));
         OpeningCharacters = ['|', '\n', '\r'];
         Options = options ?? new PipeTableOptions();
     }
@@ -86,7 +86,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 tableState.IsInvalidTable = true;
             }
             tableState.LineHasPipe = false;
-            lineBreakParser.Match(processor, ref slice);
+            _lineBreakParser.Match(processor, ref slice);
             if (!isFirstLineEmpty)
             {
                 tableState.ColumnAndLineDelimiters.Add(processor.Inline!);
@@ -100,7 +100,8 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 Span = new SourceSpan(position, position),
                 Line = globalLineIndex,
                 Column = column,
-                LocalLineIndex = localLineIndex
+                LocalLineIndex = localLineIndex,
+                IsClosed = true  // Creates flat sibling structure for O(n) traversal
             };
 
             tableState.LineHasPipe = true;
@@ -125,6 +126,8 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 return true;
             }
 
+            // With flat structure, pipes are siblings at root level
+            // Walk backwards from the last child to find pipe delimiters
             var child = container.LastChild;
             List<PipeTableDelimiterInline>? delimitersToRemove = null;
 
@@ -142,8 +145,8 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                     break;
                 }
 
-                var subContainer = child as ContainerInline;
+                // Walk siblings instead of descending into containers
-                child = subContainer?.LastChild;
+                child = child.PreviousSibling;
             }
 
             // If we have found any delimiters, transform them to literals
@@ -186,8 +189,8 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
         // Remove previous state
         state.ParserStates[Index] = null!;
 
-        // Continue
+        // Abort if not a valid table
-        if (tableState is null || container is null || tableState.IsInvalidTable || !tableState.LineHasPipe ) //|| tableState.LineIndex != state.LocalLineIndex)
+        if (tableState is null || container is null || tableState.IsInvalidTable || !tableState.LineHasPipe)
         {
             if (tableState is not null)
             {
@@ -204,11 +207,18 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
 
         // Detect the header row
         var delimiters = tableState.ColumnAndLineDelimiters;
-        // TODO: we could optimize this by merging FindHeaderRow and the cell loop
         var aligns = FindHeaderRow(delimiters);
 
         if (Options.RequireHeaderSeparator && aligns is null)
         {
+            // No valid header separator found - convert all pipe delimiters to literals
+            foreach (var inline in delimiters)
+            {
+                if (inline is PipeTableDelimiterInline pipeDelimiter)
+                {
+                    pipeDelimiter.ReplaceByLiteral();
+                }
+            }
             return true;
         }
 
@@ -224,68 +234,40 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
         var cells = tableState.Cells;
         cells.Clear();
 
-        //delimiters[0].DumpTo(state.DebugLog);
+        // Pipes may end up nested inside unmatched emphasis delimiters, e.g.:
+        //     *a | b*|
+        // Promote them to root level so we have a flat sibling structure.
+        PromoteNestedPipesToRootLevel(delimiters, container);
 
-        // delimiters contain a list of `|` and `\n` delimiters
+        // The inline tree is now flat: all pipes and line breaks are siblings at root level.
-        // The `|` delimiters are created as child containers.
+        // For example, `| a | b \n| c | d \n` produces:
-        // So the following:
+        //     [|] [a] [|] [b] [\n] [|] [c] [|] [d] [\n]
-        // | a | b \n
-        // | d | e \n
         //
-        // Will generate a tree of the following node:
+        // Tables support four row formats:
-        // |
+        //     | a | b |    (leading and trailing pipes)
-        //   a
+        //     | a | b      (leading pipe only)
-        //   |
+        //       a | b      (no leading or trailing pipes)
-        //     b
+        //       a | b |    (trailing pipe only)
-        //     \n
-        //     |
-        //       d
-        //       |
-        //         e
-        //         \n
-        // When parsing delimiters, we need to recover whether a row is of the following form:
-        // 0)  | a | b | \n
-        // 1)  | a | b \n
-        // 2)    a | b \n
-        // 3)    a | b | \n
 
-        // If the last element is not a line break, add a line break to homogenize parsing in the next loop
+        // Ensure the table ends with a line break to simplify row detection
         var lastElement = delimiters[delimiters.Count - 1];
         if (!(lastElement is LineBreakInline))
         {
-            while (true)
+            // Find the actual last sibling (there may be content after the last delimiter)
+            while (lastElement.NextSibling != null)
             {
-                if (lastElement is ContainerInline lastElementContainer)
+                lastElement = lastElement.NextSibling;
-                {
-                    var nextElement = lastElementContainer.LastChild;
-                    if (nextElement != null)
-                    {
-                        lastElement = nextElement;
-                        continue;
-                    }
-                }
-                break;
             }
 
             var endOfTable = new LineBreakInline();
-            // If the last element is a container, we have to add the EOL to its child
+            lastElement.InsertAfter(endOfTable);
-            // otherwise only next sibling
-            if (lastElement is ContainerInline)
-            {
-                ((ContainerInline)lastElement).AppendChild(endOfTable);
-            }
-            else
-            {
-                lastElement.InsertAfter(endOfTable);
-            }
             delimiters.Add(endOfTable);
             tableState.EndOfLines.Add(endOfTable);
         }
 
         int lastPipePos = 0;
 
-        // Cell loop
+        // Build table rows and cells by iterating through delimiters
-        // Reconstruct the table from the delimiters
         TableRow? row = null;
         TableRow? firstRow = null;
         for (int i = 0; i < delimiters.Count; i++)
@@ -300,9 +282,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
 
                 firstRow ??= row;
 
-                // If the first delimiter is a pipe and doesn't have any parent or previous sibling, for cases like:
+                // Skip leading pipe at start of row (e.g., `| a | b` or `| a | b |`)
-                // 0)  | a | b | \n
-                // 1)  | a | b \n
                 if (pipeSeparator != null && (delimiter.PreviousSibling is null || delimiter.PreviousSibling is LineBreakInline))
                 {
                     delimiter.Remove();
@@ -316,57 +296,37 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 }
             }
 
-            // We need to find the beginning/ending of a cell from a right delimiter. From the delimiter 'x', we need to find a (without the delimiter start `|`)
+            // Find cell content by walking backwards from this delimiter to the previous pipe or line break.
-            // So we iterate back to the first pipe or line break
+            // For `| a | b \n` at delimiter 'x':
-            //         x
+            //       [|] [a] [x] [b] [\n]
-            // 1)  | a | b \n
+            //                ^--- current delimiter
-            // 2)    a | b \n
+            // Walk back: [a] is the cell content (stop at [|])
             Inline? endOfCell = null;
             Inline? beginOfCell = null;
-            var cellContentIt = delimiter;
+            var cellContentIt = delimiter.PreviousSibling;
-            while (true)
+            while (cellContentIt != null)
             {
-                cellContentIt = cellContentIt.PreviousSibling ?? cellContentIt.Parent;
+                if (cellContentIt is LineBreakInline || cellContentIt is PipeTableDelimiterInline)
-
-                if (cellContentIt is null || cellContentIt is LineBreakInline)
-                {
                     break;
-                }
 
-                // The cell begins at the first effective child after a | or the top ContainerInline (which is not necessary to bring into the tree + it contains an invalid span calculation)
+                // Stop at the root ContainerInline (which is not necessary to bring into the tree + it contains an invalid span calculation)
-                if (cellContentIt is PipeTableDelimiterInline || (cellContentIt.GetType() == typeof(ContainerInline) && cellContentIt.Parent is null ))
+                if (cellContentIt.GetType() == typeof(ContainerInline) && cellContentIt.Parent is null)
-                {
-                    beginOfCell = ((ContainerInline)cellContentIt).FirstChild;
-                    if (endOfCell is null)
-                    {
-                        endOfCell = beginOfCell;
-                    }
                     break;
-                }
 
                 beginOfCell = cellContentIt;
-                if (endOfCell is null)
+                endOfCell ??= beginOfCell;
-                {
+
-                    endOfCell = beginOfCell;
+                cellContentIt = cellContentIt.PreviousSibling;
-                }
             }
 
-            // If the current deilimiter is a pipe `|` OR
+            // If the current delimiter is a pipe `|` OR
             // the beginOfCell/endOfCell are not null and
-            // either they are :
+            // either they are:
             // - different
             // - they contain a single element, but it is not a line break (\n) or an empty/whitespace Literal.
             // Then we can add a cell to the current row
             if (!isLine || (beginOfCell != null && endOfCell != null && ( beginOfCell != endOfCell || !(beginOfCell is LineBreakInline || (beginOfCell is LiteralInline beingOfCellLiteral && beingOfCellLiteral.Content.IsEmptyOrWhitespace())))))
             {
-                if (!isLine)
-                {
-                    // If the delimiter is a pipe, we need to remove it from the tree
-                    // so that previous loop looking for a parent will not go further on subsequent cells
-                    delimiter.Remove();
-                    lastPipePos = delimiter.Span.End;
-                }
-
                 // We trim whitespace at the beginning and ending of the cell
                 TrimStart(beginOfCell);
                 TrimEnd(endOfCell);
@@ -374,10 +334,20 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 var cellContainer = new ContainerInline();
 
                 // Copy elements from beginOfCell on the first level
+                // The pipe delimiter serves as a boundary - stop when we hit it
                 var cellIt = beginOfCell;
                 while (cellIt != null && !IsLine(cellIt) && !(cellIt is PipeTableDelimiterInline))
                 {
                     var nextSibling = cellIt.NextSibling;
+
+                    // Skip empty literals (can result from trimming)
+                    if (cellIt is LiteralInline { Content.IsEmpty: true })
+                    {
+                        cellIt.Remove();
+                        cellIt = nextSibling;
+                        continue;
+                    }
+
                     cellIt.Remove();
                     if (cellContainer.Span.IsEmpty)
                     {
@@ -390,8 +360,16 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                     cellIt = nextSibling;
                 }
 
+                if (!isLine)
+                {
+                    // Remove the pipe delimiter AFTER copying cell content
+                    // This preserves the sibling chain during the copy loop
+                    delimiter.Remove();
+                    lastPipePos = delimiter.Span.End;
+                }
+
                 // Create the cell and add it to the pending row
-                var tableParagraph = new ParagraphBlock()
+                var tableParagraph = new ParagraphBlock
                 {
                     Span = cellContainer.Span,
                     Line = cellContainer.Line,
@@ -443,8 +421,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
             endOfLine.Remove();
         }
 
-        // If we have a header row, we can remove it
+        // Mark first row as header and remove the separator row if present
-        // TODO: we could optimize this by merging FindHeaderRow and the previous loop
         var tableRow = (TableRow)table[0];
         tableRow.IsHeader = Options.RequireHeaderSeparator;
         if (aligns != null)
@@ -454,11 +431,13 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
             table.ColumnDefinitions.AddRange(aligns);
         }
 
-        // Perform delimiter processor that are coming after this processor
+        // Perform all post-processors on cell content
+        // With InsertAfter, emphasis runs before pipe table, so we need to re-run from index 0
+        // to ensure emphasis delimiters in cells are properly matched
         foreach (var cell in cells)
         {
             var paragraph = (ParagraphBlock) cell[0];
-            state.PostProcessInlines(postInlineProcessorIndex + 1, paragraph.Inline, null, true);
+            state.PostProcessInlines(0, paragraph.Inline, null, true);
             if (paragraph.Inline?.LastChild is not null)
             {
                 paragraph.Inline.Span.End = paragraph.Inline.LastChild.Span.End;
@@ -548,7 +527,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 continue;
             }
 
-            // The last delimiter is always null,
+            // Parse the separator row (second row) to extract column alignments
             for (int j = i + 1; j < delimiters.Count; j++)
             {
                 var delimiter = delimiters[j];
@@ -560,11 +539,13 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                     continue;
                 }
 
-                // Check the left side of a `|` delimiter
+                // Parse the content before this delimiter as a column definition (e.g., `:---`, `---:`, `:---:`)
+                // Skip if previous sibling is a pipe (empty cell) or whitespace
                 TableColumnAlign? align = null;
                 int delimiterCount = 0;
                 if (delimiter.PreviousSibling != null &&
-                    !(delimiter.PreviousSibling is LiteralInline li && li.Content.IsEmptyOrWhitespace()) && // ignore parsed whitespace
+                    !(delimiter.PreviousSibling is PipeTableDelimiterInline) &&
+                    !(delimiter.PreviousSibling is LiteralInline li && li.Content.IsEmptyOrWhitespace()) &&
                     !ParseHeaderString(delimiter.PreviousSibling, out align, out delimiterCount))
                 {
                     break;
@@ -576,14 +557,13 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
                 totalDelimiterCount += delimiterCount;
                 columnDefinitions.Add(new TableColumnDefinition() { Alignment =  align, Width = delimiterCount});
 
-                // If this is the last delimiter, we need to check the right side of the `|` delimiter
+                // If this is the last pipe, check for a trailing column definition (row without trailing pipe)
+                // e.g., `| :--- | ---:` has content after the last pipe
                 if (nextDelimiter is null)
                 {
-                    var nextSibling = columnDelimiter != null
+                    var nextSibling = delimiter.NextSibling;
-                        ? columnDelimiter.FirstChild
-                        : delimiter.NextSibling;
 
-                    // If there is no content after
+                    // No trailing content means row ends with pipe: `| :--- |`
                     if (IsNullOrSpace(nextSibling))
                     {
                         isValidRow = true;
@@ -664,9 +644,9 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
 
     private static void TrimStart(Inline? inline)
     {
-        while (inline is ContainerInline && !(inline is DelimiterInline))
+        while (inline is ContainerInline containerInline && !(containerInline is DelimiterInline))
         {
-            inline = ((ContainerInline)inline).FirstChild;
+            inline = containerInline.FirstChild;
         }
 
         if (inline is LiteralInline literal)
@@ -677,6 +657,13 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
 
     private static void TrimEnd(Inline? inline)
     {
+        // Walk into containers to find the last leaf to trim
+        // Skip PipeTableDelimiterInline but walk into other containers (including emphasis)
+        while (inline is ContainerInline container && !(inline is PipeTableDelimiterInline))
+        {
+            inline = container.LastChild;
+        }
+
         if (inline is LiteralInline literal)
         {
             literal.Content.TrimEnd();
@@ -697,6 +684,106 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
         return false;
     }
 
+    /// <summary>
+    /// Promotes nested pipe delimiters and line breaks to root level.
+    /// </summary>
+    /// <remarks>
+    /// Handles cases like `*a | b*|` where the pipe ends up inside an unmatched emphasis container.
+    /// After promotion, all delimiters become siblings at root level for consistent cell boundary detection.
+    /// </remarks>
+    private static void PromoteNestedPipesToRootLevel(List<Inline> delimiters, ContainerInline root)
+    {
+        for (int i = 0; i < delimiters.Count; i++)
+        {
+            var delimiter = delimiters[i];
+
+            // Handle both pipe delimiters and line breaks
+            bool isPipe = delimiter is PipeTableDelimiterInline;
+            bool isLineBreak = delimiter is LineBreakInline;
+            if (!isPipe && !isLineBreak)
+                continue;
+
+            // Skip if already at root level
+            if (delimiter.Parent == root)
+                continue;
+
+            // Find the top-level ancestor (direct child of root)
+            var ancestor = delimiter.Parent;
+            while (ancestor?.Parent != null && ancestor.Parent != root)
+            {
+                ancestor = ancestor.Parent;
+            }
+
+            if (ancestor is null || ancestor.Parent != root)
+                continue;
+
+            // Split: promote delimiter to be sibling of ancestor
+            SplitContainerAtDelimiter(delimiter, ancestor);
+        }
+    }
+
+    /// <summary>
+    /// Splits a container at the delimiter, promoting the delimiter to root level.
+    /// </summary>
+    /// <remarks>
+    /// For input `*a | b*`, the pipe is inside the emphasis container:
+    ///     EmphasisDelimiter { "a", Pipe, "b" }
+    /// After splitting:
+    ///     EmphasisDelimiter { "a" }, Pipe, Container { "b" }
+    /// </remarks>
+    private static void SplitContainerAtDelimiter(Inline delimiter, Inline ancestor)
+    {
+        if (delimiter.Parent is not { } parent) return;
+
+        // Collect content after the delimiter
+        var contentAfter = new List<Inline>();
+        var current = delimiter.NextSibling;
+        while (current != null)
+        {
+            contentAfter.Add(current);
+            current = current.NextSibling;
+        }
+
+        // Remove content after delimiter from parent
+        foreach (var inline in contentAfter)
+        {
+            inline.Remove();
+        }
+
+        // Remove delimiter from parent
+        delimiter.Remove();
+
+        // Insert delimiter after the ancestor (at root level)
+        ancestor.InsertAfter(delimiter);
+
+        // If there's content after, wrap in new container and insert after delimiter
+        if (contentAfter.Count > 0)
+        {
+            // Create new container matching the original parent type
+            var newContainer = CreateMatchingContainer(parent);
+            foreach (var inline in contentAfter)
+            {
+                newContainer.AppendChild(inline);
+            }
+            delimiter.InsertAfter(newContainer);
+        }
+    }
+
+    /// <summary>
+    /// Creates a container to wrap content split from the source container.
+    /// </summary>
+    private static ContainerInline CreateMatchingContainer(ContainerInline source)
+    {
+        // Emphasis processing runs before pipe table processing, so emphasis delimiters
+        // are already resolved. A plain ContainerInline suffices.
+        return new ContainerInline
+        {
+            Span = source.Span,
+            Line = source.Line,
+            Column = source.Column
+        };
+    }
+
     private sealed class TableState
     {
         public bool IsInvalidTable { get; set; }

src/Markdig/Helpers/LinkHelper.cs

@@ -1,5 +1,5 @@
 // Copyright (c) Alexandre Mutel. All rights reserved.
-// This file is licensed under the BSD-Clause 2 license. 
+// This file is licensed under the BSD-Clause 2 license.
 // See the license.txt file in the project root for more information.
 
 using Markdig.Syntax;
@@ -215,13 +215,13 @@ public static class LinkHelper
             return false;
         }
 
-        // An absolute URI, for these purposes, consists of a scheme followed by a colon (:) 
+        // An absolute URI, for these purposes, consists of a scheme followed by a colon (:)
-        // followed by zero or more characters other than ASCII whitespace and control characters, <, and >. 
+        // followed by zero or more characters other than ASCII whitespace and control characters, <, and >.
         // If the URI includes these characters, they must be percent-encoded (e.g. %20 for a space).
         // A URI that would end with a full stop (.) is treated instead as ending immediately before the full stop.
 
-        // a scheme is any sequence of 2–32 characters 
+        // a scheme is any sequence of 2–32 characters
-        // beginning with an ASCII letter 
+        // beginning with an ASCII letter
         // and followed by any combination of ASCII letters, digits, or the symbols plus (”+”), period (”.”), or hyphen (”-”).
 
         // An email address, for these purposes, is anything that matches the non-normative regex from the HTML5 spec:
@@ -276,7 +276,7 @@ public static class LinkHelper
 
             if (isValidChar)
             {
-                // a scheme is any sequence of 2–32 characters 
+                // a scheme is any sequence of 2–32 characters
                 if (state > 0 && builder.Length >= 32)
                 {
                     goto ReturnFalse;
@@ -307,7 +307,7 @@ public static class LinkHelper
             }
         }
 
-        // append ':' or '@' 
+        // append ':' or '@'
         builder.Append(c);
 
         if (state < 0)
@@ -415,10 +415,10 @@ public static class LinkHelper
 
     public static bool TryParseInlineLink(ref StringSlice text, out string? link, out string? title, out SourceSpan linkSpan, out SourceSpan titleSpan)
     {
-        // 1. An inline link consists of a link text followed immediately by a left parenthesis (, 
+        // 1. An inline link consists of a link text followed immediately by a left parenthesis (,
         // 2. optional whitespace,  TODO: specs: is it whitespace or multiple whitespaces?
-        // 3. an optional link destination, 
+        // 3. an optional link destination,
-        // 4. an optional link title separated from the link destination by whitespace, 
+        // 4. an optional link title separated from the link destination by whitespace,
         // 5. optional whitespace,  TODO: specs: is it whitespace or multiple whitespaces?
         // 6. and a right parenthesis )
         bool isValid = false;
@@ -429,7 +429,7 @@ public static class LinkHelper
         linkSpan = SourceSpan.Empty;
         titleSpan = SourceSpan.Empty;
 
-        // 1. An inline link consists of a link text followed immediately by a left parenthesis (, 
+        // 1. An inline link consists of a link text followed immediately by a left parenthesis (,
         if (c == '(')
         {
             text.SkipChar();
@@ -505,10 +505,10 @@ public static class LinkHelper
         out SourceSpan triviaAfterTitle,
         out bool urlHasPointyBrackets)
     {
-        // 1. An inline link consists of a link text followed immediately by a left parenthesis (, 
+        // 1. An inline link consists of a link text followed immediately by a left parenthesis (,
         // 2. optional whitespace,  TODO: specs: is it whitespace or multiple whitespaces?
-        // 3. an optional link destination, 
+        // 3. an optional link destination,
-        // 4. an optional link title separated from the link destination by whitespace, 
+        // 4. an optional link title separated from the link destination by whitespace,
         // 5. optional whitespace,  TODO: specs: is it whitespace or multiple whitespaces?
         // 6. and a right parenthesis )
         bool isValid = false;
@@ -526,7 +526,7 @@ public static class LinkHelper
         urlHasPointyBrackets = false;
         titleEnclosingCharacter = '\0';
 
-        // 1. An inline link consists of a link text followed immediately by a left parenthesis (, 
+        // 1. An inline link consists of a link text followed immediately by a left parenthesis (,
         if (c == '(')
         {
             text.SkipChar();
@@ -773,7 +773,7 @@ public static class LinkHelper
 
         var c = text.CurrentChar;
 
-        // a sequence of zero or more characters between an opening < and a closing > 
+        // a sequence of zero or more characters between an opening < and a closing >
         // that contains no line breaks, or unescaped < or > characters, or
         if (c == '<')
         {
@@ -820,9 +820,9 @@ public static class LinkHelper
         else
         {
             // a nonempty sequence of characters that does not start with <, does not include ASCII space or control characters,
-            // and includes parentheses only if (a) they are backslash-escaped or (b) they are part of a 
+            // and includes parentheses only if (a) they are backslash-escaped or (b) they are part of a
-            // balanced pair of unescaped parentheses that is not itself inside a balanced pair of unescaped 
+            // balanced pair of unescaped parentheses that is not itself inside a balanced pair of unescaped
-            // parentheses. 
+            // parentheses.
             bool hasEscape = false;
             int openedParent = 0;
             while (true)
@@ -922,7 +922,7 @@ public static class LinkHelper
 
         var c = text.CurrentChar;
 
-        // a sequence of zero or more characters between an opening < and a closing > 
+        // a sequence of zero or more characters between an opening < and a closing >
         // that contains no line breaks, or unescaped < or > characters, or
         if (c == '<')
         {
@@ -969,9 +969,9 @@ public static class LinkHelper
         else
         {
             // a nonempty sequence of characters that does not start with <, does not include ASCII space or control characters,
-            // and includes parentheses only if (a) they are backslash-escaped or (b) they are part of a 
+            // and includes parentheses only if (a) they are backslash-escaped or (b) they are part of a
-            // balanced pair of unescaped parentheses that is not itself inside a balanced pair of unescaped 
+            // balanced pair of unescaped parentheses that is not itself inside a balanced pair of unescaped
-            // parentheses. 
+            // parentheses.
             bool hasEscape = false;
             int openedParent = 0;
             while (true)
@@ -1201,7 +1201,7 @@ public static class LinkHelper
 
         if (c != '\0' && c != '\n' && c != '\r')
         {
-            // If we were able to parse the url but the title doesn't end with space, 
+            // If we were able to parse the url but the title doesn't end with space,
             // we are still returning a valid definition
             if (newLineCount > 0 && title != null)
             {
@@ -1341,7 +1341,7 @@ public static class LinkHelper
 
         if (c != '\0' && c != '\n' && c != '\r')
         {
-            // If we were able to parse the url but the title doesn't end with space, 
+            // If we were able to parse the url but the title doesn't end with space,
             // we are still returning a valid definition
             if (newLineCount > 0 && title != null)
             {

src/Markdig/Parsers/Inlines/CodeInlineParser.cs

@@ -85,7 +85,8 @@ public class CodeInlineParser : InlineParser
                     // We saw the start of a code inline, but the close sticks are not present on the same line.
                     // If the next line starts with a pipe character, this is likely an incomplete CodeInline within a table.
                     // Treat it as regular text to avoid breaking the overall table shape.
-                    if (processor.Inline != null && processor.Inline.ContainsParentOfType<PipeTableDelimiterInline>())
+                    // Use ContainsParentOrSiblingOfType to handle both nested and flat pipe table structures.
+                    if (processor.Inline != null && processor.Inline.ContainsParentOrSiblingOfType<PipeTableDelimiterInline>())
                     {
                         slice.Start = openingStart;
                         return false;

src/Markdig/Parsers/Inlines/EmphasisInlineParser.cs

@@ -125,7 +125,10 @@ public class EmphasisInlineParser : InlineParser, IPostInlineProcessor
                 }
 
                 // Follow DelimiterInline (EmphasisDelimiter, TableDelimiter...)
-                child = delimiterInline.FirstChild;
+                // If the delimiter has IsClosed=true (e.g., pipe table delimiter), it has no children
+                // In that case, continue to next sibling instead of stopping
+                var firstChild = delimiterInline.FirstChild;
+                child = firstChild ?? delimiterInline.NextSibling;
             }
             else
             {

src/Markdig/Syntax/Inlines/Inline.cs

@@ -216,6 +216,47 @@ public abstract class Inline : MarkdownObject, IInline
         return false;
     }
 
+    /// <summary>
+    /// Determines whether there is a sibling of the specified type among root-level siblings.
+    /// This walks up to find the root container, then checks all siblings.
+    /// </summary>
+    /// <typeparam name="T">Type of the sibling to check</typeparam>
+    /// <returns><c>true</c> if a sibling of the specified type exists; <c>false</c> otherwise</returns>
+    public bool ContainsParentOrSiblingOfType<T>() where T : Inline
+    {
+        // First check parents (handles nested case)
+        if (ContainsParentOfType<T>())
+        {
+            return true;
+        }
+
+        // Then check siblings at root level (handles flat case)
+        // Find the root container
+        var root = Parent;
+        while (root?.Parent != null)
+        {
+            root = root.Parent;
+        }
+
+        if (root is not ContainerInline container)
+        {
+            return false;
+        }
+
+        // Walk siblings looking for the type
+        var sibling = container.FirstChild;
+        while (sibling != null)
+        {
+            if (sibling is T)
+            {
+                return true;
+            }
+            sibling = sibling.NextSibling;
+        }
+
+        return false;
+    }
+
     /// <summary>
     /// Iterates on parents of the specified type.
     /// </summary>