1 files changed, 139 insertions, 0 deletions
diff --git a/myst_parser/mdit_to_docutils/html_to_nodes.py b/myst_parser/mdit_to_docutils/html_to_nodes.py
new file mode 100644
index 0000000..2cc3066
--- /dev/null
+++ b/myst_parser/mdit_to_docutils/html_to_nodes.py
@@ -0,0 +1,139 @@
+"""Convert HTML to docutils nodes."""
+from __future__ import annotations
+
+import re
+from typing import TYPE_CHECKING
+
+from docutils import nodes
+
+from myst_parser.parsers.parse_html import Data, tokenize_html
+
+if TYPE_CHECKING:
+    from .base import DocutilsRenderer
+
+
+def make_error(
+    document: nodes.document, error_msg: str, text: str, line_number: int
+) -> nodes.system_message:
+    return document.reporter.error(
+        error_msg,
+        nodes.literal_block(text, text),
+        line=line_number,
+    )
+
+
+OPTION_KEYS_IMAGE = {"class", "alt", "height", "width", "align", "name"}
+# note: docutils also has scale and target
+
+OPTION_KEYS_ADMONITION = {"class", "name"}
+
+# See https://github.com/micromark/micromark-extension-gfm-tagfilter
+RE_FLOW = re.compile(
+    r"<(\/?)(iframe|noembed|noframes|plaintext|script|style|title|textarea|xmp)(?=[\t\n\f\r />])",
+    re.IGNORECASE,
+)
+
+
+def default_html(text: str, source: str, line_number: int) -> list[nodes.Element]:
+    raw_html = nodes.raw("", text, format="html")
+    raw_html.source = source
+    raw_html.line = line_number
+    return [raw_html]
+
+
+def html_to_nodes(
+    text: str, line_number: int, renderer: DocutilsRenderer
+) -> list[nodes.Element]:
+    """Convert HTML to docutils nodes."""
+    if renderer.md_config.gfm_only:
+        text, _ = RE_FLOW.subn(lambda s: s.group(0).replace("<", "&lt;"), text)
+
+    enable_html_img = "html_image" in renderer.md_config.enable_extensions
+    enable_html_admonition = "html_admonition" in renderer.md_config.enable_extensions
+    if not (enable_html_img or enable_html_admonition):
+        return default_html(text, renderer.document["source"], line_number)
+
+    # parse the HTML to AST
+    try:
+        root = tokenize_html(text).strip(inplace=True, recurse=False)
+    except Exception:
+        msg_node = renderer.create_warning(
+            "HTML could not be parsed", line=line_number, subtype="html"
+        )
+        return ([msg_node] if msg_node else []) + default_html(
+            text, renderer.document["source"], line_number
+        )
+
+    if len(root) < 1:
+        # if empty
+        return default_html(text, renderer.document["source"], line_number)
+
+    if not all(
+        (enable_html_img and child.name == "img")
+        or (
+            enable_html_admonition
+            and child.name == "div"
+            and "admonition" in child.attrs.classes
+        )
+        for child in root
+    ):
+        return default_html(text, renderer.document["source"], line_number)
+
+    nodes_list = []
+    for child in root:
+
+        if child.name == "img":
+            if "src" not in child.attrs:
+                return [
+                    renderer.reporter.error(
+                        "<img> missing 'src' attribute", line=line_number
+                    )
+                ]
+            content = "\n".join(
+                f":{k}: {v}"
+                for k, v in sorted(child.attrs.items())
+                if k in OPTION_KEYS_IMAGE
+            )
+            nodes_list.extend(
+                renderer.run_directive(
+                    "image", child.attrs["src"], content, line_number
+                )
+            )
+
+        else:
+            children = child.strip().children
+            if (
+                children
+                and children[0].name in ("div", "p")
+                and (
+                    "title" in children[0].attrs.classes
+                    or "admonition-title" in children[0].attrs.classes
+                )
+            ):
+                title = "".join(child.render() for child in children.pop(0))
+            else:
+                title = "Note"
+
+            options = "\n".join(
+                f":{k}: {v}"
+                for k, v in sorted(child.attrs.items())
+                if k in OPTION_KEYS_ADMONITION
+            ).rstrip()
+            new_children = []
+            for child in children:
+                if child.name == "p":
+                    new_children.extend(child.children)
+                    new_children.append(Data("\n\n"))
+                else:
+                    new_children.append(child)
+            content = (
+                options
+                + ("\n\n" if options else "")
+                + "".join(child.render() for child in new_children).lstrip()
+            )
+
+            nodes_list.extend(
+                renderer.run_directive("admonition", title, content, line_number)
+            )
+
+    return nodes_list