fix: fix empty heading breaks paragraph and table (#3050)

Author: UziTech

src/rules.ts

@@ -131,7 +131,7 @@ block.lheading = edit(block.lheading)
 
 block.paragraph = edit(block._paragraph)
   .replace('hr', block.hr)
-  .replace('heading', ' {0,3}#{1,6} ')
+  .replace('heading', ' {0,3}#{1,6}(?:\\s|$)')
   .replace('|lheading', '') // setex headings don't interrupt commonmark paragraphs
   .replace('|table', '')
   .replace('blockquote', ' {0,3}>')
@@ -164,7 +164,7 @@ block.gfm = {
 
 block.gfm.table = edit(block.gfm.table as Rule)
   .replace('hr', block.hr)
-  .replace('heading', ' {0,3}#{1,6} ')
+  .replace('heading', ' {0,3}#{1,6}(?:\\s|$)')
   .replace('blockquote', ' {0,3}>')
   .replace('code', ' {4}[^\\n]')
   .replace('fences', ' {0,3}(?:`{3,}(?=[^`\\n]*\\n)|~{3,})[^\\n]*\\n')
@@ -175,7 +175,7 @@ block.gfm.table = edit(block.gfm.table as Rule)
 
 block.gfm.paragraph = edit(block._paragraph)
   .replace('hr', block.hr)
-  .replace('heading', ' {0,3}#{1,6} ')
+  .replace('heading', ' {0,3}#{1,6}(?:\\s|$)')
   .replace('|lheading', '') // setex headings don't interrupt commonmark paragraphs
   .replace('table', block.gfm.table as RegExp) // interrupt paragraphs with table
   .replace('blockquote', ' {0,3}>')

test/specs/new/empty_heading_following_paragraph.html

@@ -0,0 +1,5 @@
+<p>Newline after heading</p>
+<h2></h2>
+
+<p>No newline at the end</p>
+<h2></h2>

test/specs/new/empty_heading_following_paragraph.md

@@ -0,0 +1,5 @@
+Newline after heading
+##
+
+No newline at the end
+##

test/specs/new/empty_heading_following_paragraph_nogfm.html

@@ -0,0 +1,5 @@
+<p>Newline after heading</p>
+<h2></h2>
+
+<p>No newline at the end</p>
+<h2></h2>

test/specs/new/empty_heading_following_paragraph_nogfm.md

@@ -0,0 +1,8 @@
+---
+gfm: false
+---
+Newline after heading
+##
+
+No newline at the end
+##

test/specs/new/empty_heading_following_table.html

@@ -0,0 +1,41 @@
+<table>
+  <thead>
+    <tr>
+      <th>a</th>
+      <th>b</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>1</td>
+      <td>2</td>
+    </tr>
+    <tr>
+      <td>3</td>
+      <td>4</td>
+    </tr>
+  </tbody>
+</table>
+<h2></h2>
+
+<p>No newline at the end</p>
+
+<table>
+  <thead>
+    <tr>
+      <th>a</th>
+      <th>b</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>1</td>
+      <td>2</td>
+    </tr>
+    <tr>
+      <td>3</td>
+      <td>4</td>
+    </tr>
+  </tbody>
+</table>
+<h2></h2>

test/specs/new/empty_heading_following_table.md

@@ -0,0 +1,13 @@
+| a | b |
+| - | - |
+| 1 | 2 |
+| 3 | 4 |
+##
+
+No newline at the end
+
+| a | b |
+| - | - |
+| 1 | 2 |
+| 3 | 4 |
+##