Fix to calculate LinkReferenceDefinition span positions from StringLineGroup.Lines (#931)

* Fix to calculate LinkReferenceDefinition span positions from StringLineGroup.Lines

* Add test case in TestMultilineInBlockquote

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Change from startPosition + span.End - span.Start to GetAbsolutePosition(lines, span.End)

* Move ConvertToAbsoluteSpan and GetAbsolutePosition to StringLineGroup

* Remove '\r' check in Write(ReadOnlySpan<char>)

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: prozolic

src/Markdig.Tests/RoundtripSpecs/TestLinkReferenceDefinition.cs

@@ -209,4 +209,16 @@ public void TestSetextHeader(string value)
     {
         RoundTrip(value);
     }
+
+    [TestCase("> [foo]: /url 'the title'\n")]
+    [TestCase("> [foo]: /url\n> 'the title'\n")]
+    [TestCase("> [foo]:\n> /url 'the title'\n")]
+    [TestCase("> [foo]:\n> /url\n> 'the title'\n")]
+    [TestCase("> [foo]:\n> /url\n>\n> [foo]\n")]
+    [TestCase("> [foo]:\n> /url 'the title'\n>\n> [foo]\n")]
+    [TestCase("> [foo]:\n> /url\n> 'the title'\n>\n> [foo]\n")]
+    public void TestMultilineInBlockquote(string value)
+    {
+        RoundTrip(value);
+    }
 }

src/Markdig/Helpers/StringLineGroup.cs

@@ -2,6 +2,7 @@
 // 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;
 using System.Collections;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
@@ -190,6 +191,33 @@ public void Trim()
         }
     }
 
+    internal SourceSpan ConvertToAbsoluteSpan(SourceSpan span)
+    {
+        if (span.IsEmpty || Count == 0) return span;
+
+        var startPosition = GetAbsolutePosition(span.Start);
+        var endPosition = GetAbsolutePosition(span.End);
+
+        return new SourceSpan(startPosition, endPosition);
+    }
+
+    private int GetAbsolutePosition(int position)
+    {
+        int offset = 0;
+        for (int i = 0; i < Count; i++)
+        {
+            ref StringSlice slice = ref Lines[i].Slice;
+            var lineLength = slice.Length + slice.NewLine.Length();
+
+            if (i == Count - 1 || position < offset + lineLength)
+            {
+                return slice.Start + (position - offset);
+            }
+            offset += lineLength;
+        }
+        return Lines[Count - 1].Slice.End + 1;
+    }
+
     /// <summary>
     /// Gets or sets the enumerator.
     /// </summary>

src/Markdig/Parsers/ParagraphBlockParser.cs

@@ -212,13 +212,11 @@ private static bool TryMatchLinkReferenceDefinition(ref StringLineGroup lines, B
 
                 // Correct the locations of each field
                 linkReferenceDefinition.Line = lines.Lines[0].Line;
-                int startPosition = lines.Lines[0].Slice.Start;
-
-                linkReferenceDefinition.Span        = linkReferenceDefinition.Span      .MoveForward(startPosition);
-                linkReferenceDefinition.LabelSpan   = linkReferenceDefinition.LabelSpan .MoveForward(startPosition);
-                linkReferenceDefinition.UrlSpan     = linkReferenceDefinition.UrlSpan   .MoveForward(startPosition);
-                linkReferenceDefinition.TitleSpan   = linkReferenceDefinition.TitleSpan .MoveForward(startPosition);
 
+                linkReferenceDefinition.Span = lines.ConvertToAbsoluteSpan(linkReferenceDefinition.Span);
+                linkReferenceDefinition.LabelSpan = lines.ConvertToAbsoluteSpan(linkReferenceDefinition.LabelSpan);
+                linkReferenceDefinition.UrlSpan = lines.ConvertToAbsoluteSpan(linkReferenceDefinition.UrlSpan);
+                linkReferenceDefinition.TitleSpan = lines.ConvertToAbsoluteSpan(linkReferenceDefinition.TitleSpan);
                 lines = iterator.Remaining();
             }
             else
@@ -256,24 +254,23 @@ private static bool TryMatchLinkReferenceDefinitionTrivia(ref StringLineGroup li
                 // Correct the locations of each field
                 lrd.Line = lines.Lines[0].Line;
                 var text = lines.Lines[0].Slice.Text;
-                int startPosition = lines.Lines[0].Slice.Start;
-
-                triviaBeforeLabel = triviaBeforeLabel.MoveForward(startPosition);
-                labelWithTrivia = labelWithTrivia.MoveForward(startPosition);
-                triviaBeforeUrl = triviaBeforeUrl.MoveForward(startPosition);
-                unescapedUrl = unescapedUrl.MoveForward(startPosition);
-                triviaBeforeTitle = triviaBeforeTitle.MoveForward(startPosition);
-                unescapedTitle = unescapedTitle.MoveForward(startPosition);
-                triviaAfterTitle = triviaAfterTitle.MoveForward(startPosition);
-                lrd.Span = lrd.Span.MoveForward(startPosition);
+
+                triviaBeforeLabel = lines.ConvertToAbsoluteSpan(triviaBeforeLabel);
+                labelWithTrivia = lines.ConvertToAbsoluteSpan(labelWithTrivia);
+                triviaBeforeUrl = lines.ConvertToAbsoluteSpan(triviaBeforeUrl);
+                unescapedUrl = lines.ConvertToAbsoluteSpan(unescapedUrl);
+                triviaBeforeTitle = lines.ConvertToAbsoluteSpan(triviaBeforeTitle);
+                unescapedTitle = lines.ConvertToAbsoluteSpan(unescapedTitle);
+                triviaAfterTitle = lines.ConvertToAbsoluteSpan(triviaAfterTitle);
+                lrd.Span = lines.ConvertToAbsoluteSpan(lrd.Span);
                 lrd.TriviaBefore = new StringSlice(text, triviaBeforeLabel.Start, triviaBeforeLabel.End);
-                lrd.LabelSpan = lrd.LabelSpan.MoveForward(startPosition);
+                lrd.LabelSpan = lines.ConvertToAbsoluteSpan(lrd.LabelSpan);
                 lrd.LabelWithTrivia = new StringSlice(text, labelWithTrivia.Start, labelWithTrivia.End);
                 lrd.TriviaBeforeUrl = new StringSlice(text, triviaBeforeUrl.Start, triviaBeforeUrl.End);
-                lrd.UrlSpan = lrd.UrlSpan.MoveForward(startPosition);
+                lrd.UrlSpan = lines.ConvertToAbsoluteSpan(lrd.UrlSpan);
                 lrd.UnescapedUrl = new StringSlice(text, unescapedUrl.Start, unescapedUrl.End);
                 lrd.TriviaBeforeTitle = new StringSlice(text, triviaBeforeTitle.Start, triviaBeforeTitle.End);
-                lrd.TitleSpan = lrd.TitleSpan.MoveForward(startPosition);
+                lrd.TitleSpan = lines.ConvertToAbsoluteSpan(lrd.TitleSpan);
                 lrd.UnescapedTitle = new StringSlice(text, unescapedTitle.Start, unescapedTitle.End);
                 lrd.TriviaAfter = new StringSlice(text, triviaAfterTitle.Start, triviaAfterTitle.End);
                 lrd.LinesBefore = paragraph.LinesBefore;
@@ -292,4 +289,5 @@ private static bool TryMatchLinkReferenceDefinitionTrivia(ref StringLineGroup li
 
         return atLeastOneFound;
     }
+
 }

src/Markdig/Renderers/TextRendererBase.cs

@@ -320,6 +320,10 @@ public void Write(ReadOnlySpan<char> content)
         {
             WriteIndent();
             WriteRaw(content);
+            if (content[content.Length - 1] == '\n')
+            {
+                previousWasLine = true;
+            }
         }
     }