From d1990c5c2f4d5a1281924582f7a8ca4744d70c12 Mon Sep 17 00:00:00 2001
From: James Knight <james.d.knight@live.com>
Date: Fri, 19 Jul 2024 21:57:06 -0400
Subject: [PATCH] Support building line blocks with markdown-it hardbreaks

Provides the ability to build docutils' line-block nodes if an inline
element contains hardbreaks. When a hardbreak is detected as a child of
an inline token, a line-block will be created and child tokens will be
rendered into a prepared line node. Child nodes are placed into a line
node until the next hardbreak is detected, where a new line node is
created to hold the next child set. The process repeats until all
children are processed.

Signed-off-by: James Knight <james.d.knight@live.com>
---
 myst_parser/mdit_to_docutils/base.py          | 53 +++++++++++++++----
 .../fixtures/docutil_syntax_elements.md       | 11 ++--
 .../fixtures/sphinx_syntax_elements.md        | 11 ++--
 3 files changed, 53 insertions(+), 22 deletions(-)

diff --git a/myst_parser/mdit_to_docutils/base.py b/myst_parser/mdit_to_docutils/base.py
index 520a3c80..8bfcd912 100644
--- a/myst_parser/mdit_to_docutils/base.py
+++ b/myst_parser/mdit_to_docutils/base.py
@@ -392,15 +392,19 @@ def current_node_context(
     def render_children(self, token: SyntaxTreeNode) -> None:
         """Render the children of a token."""
         for child in token.children or []:
-            if f"render_{child.type}" in self.rules:
-                self.rules[f"render_{child.type}"](child)
-            else:
-                self.create_warning(
-                    f"No render method for: {child.type}",
-                    MystWarnings.RENDER_METHOD,
-                    line=token_line(child, default=0),
-                    append_to=self.current_node,
-                )
+            self.render_token(child)
+
+    def render_token(self, token: SyntaxTreeNode) -> None:
+        """Render a token."""
+        if f"render_{token.type}" in self.rules:
+            self.rules[f"render_{token.type}"](token)
+        else:
+            self.create_warning(
+                f"No render method for: {token.type}",
+                MystWarnings.RENDER_METHOD,
+                line=token_line(token, default=0),
+                append_to=self.current_node,
+            )
 
     def add_line_and_source_path(self, node, token: SyntaxTreeNode) -> None:
         """Copy the line number and document source path to the docutils node."""
@@ -526,7 +530,36 @@ def render_paragraph(self, token: SyntaxTreeNode) -> None:
             self.render_children(token)
 
     def render_inline(self, token: SyntaxTreeNode) -> None:
-        self.render_children(token)
+        needs_lineblock = False
+        for child in token.children or []:
+            if child.type == "hardbreak":
+                needs_lineblock = True
+                break
+
+        if not needs_lineblock:
+            self.render_children(token)
+            return
+
+        # if we have any hard breaks, we will build a line block and
+        # prepare line nodes for each group of children between these
+        # breaks
+        lineblock = nodes.line_block()
+        self.add_line_and_source_path(lineblock, token)
+        self.current_node.append(lineblock)
+
+        current_line = nodes.line()
+        self.add_line_and_source_path(current_line, token)
+        lineblock.append(current_line)
+
+        for child in token.children or []:
+            if child.type == "hardbreak":
+                current_line = nodes.line()
+                self.add_line_and_source_path(current_line, token)
+                lineblock.append(current_line)
+                continue
+
+            with self.current_node_context(current_line):
+                self.render_token(child)
 
     def render_text(self, token: SyntaxTreeNode) -> None:
         self.current_node.append(nodes.Text(token.content))
diff --git a/tests/test_renderers/fixtures/docutil_syntax_elements.md b/tests/test_renderers/fixtures/docutil_syntax_elements.md
index 6badaa4c..42ab3b10 100644
--- a/tests/test_renderers/fixtures/docutil_syntax_elements.md
+++ b/tests/test_renderers/fixtures/docutil_syntax_elements.md
@@ -14,12 +14,11 @@ bar
 .
 <document source="notset">
     <paragraph>
-        foo
-        <raw format="html" xml:space="preserve">
-            <br />
-        <raw format="latex" xml:space="preserve">
-            \\
-        bar
+        <line_block>
+            <line>
+                foo
+            <line>
+                bar
 .
 
 Strong:
diff --git a/tests/test_renderers/fixtures/sphinx_syntax_elements.md b/tests/test_renderers/fixtures/sphinx_syntax_elements.md
index cdc72b77..756c7183 100644
--- a/tests/test_renderers/fixtures/sphinx_syntax_elements.md
+++ b/tests/test_renderers/fixtures/sphinx_syntax_elements.md
@@ -14,12 +14,11 @@ bar
 .
 <document source="<src>/index.md">
     <paragraph>
-        foo
-        <raw format="html" xml:space="preserve">
-            <br />
-        <raw format="latex" xml:space="preserve">
-            \\
-        bar
+        <line_block>
+            <line>
+                foo
+            <line>
+                bar
 .
 
 Strong: