feat: support GFM table of markdown (#345)

Author: Moskize91

.vscode/settings.json

@@ -35,6 +35,7 @@
         "frombytes",
         "gundam",
         "LOCALAPPDATA",
+        "markdownify",
         "MATHML",
         "mediabox",
         "metas",
@@ -55,6 +56,7 @@
         "pypdf",
         "pytest",
         "REGX",
+        "rowspan",
         "SSOHH'mm",
         "tagfilter",
         "tiktoken",

pdf_craft/markdown/render/layouts.py

@@ -13,6 +13,7 @@
     RefIdMap,
 )
 from ..paragraph import render_markdown_paragraph
+from .table import render_table_content
 
 _MAX_TOC_LEVELS = 3
 _MAX_TITLE_LEVELS = 6
@@ -183,9 +184,13 @@ def _render_asset_content(
         if asset.content:
             if has_content_before:
                 yield "\n\n"
-            yield from render_markdown_paragraph(
-                children=asset.content,
-                render_payload=render_member,
+            yield render_table_content(
+                html_string="".join(
+                    render_markdown_paragraph(
+                        children=asset.content,
+                        render_payload=render_member,
+                    )
+                )
             )
 
     elif asset.ref == "image":

pdf_craft/markdown/render/table.py

@@ -0,0 +1,82 @@
+from typing import TYPE_CHECKING
+
+from markdownify import MarkdownConverter
+
+if TYPE_CHECKING:
+    from bs4 import Tag
+
+
+class _TableComplexityException(Exception):
+    pass
+
+
+class _GFMTableConverter(MarkdownConverter):
+    """
+    Custom converter that detects complex table features.
+
+    The base markdownify library will silently convert complex HTML tables to
+    GFM pipe tables, but this loses information (e.g., merged cells become
+    empty cells). This custom converter detects such cases and raises an
+    exception to allow fallback to HTML.
+
+    Background:
+    - GFM markdown tables don't support colspan/rowspan
+    - markdownify doesn't provide rowspan support (issue #121):
+      https://github.com/matthewwithanm/python-markdownify/issues/121
+    - Instead of silent data loss, we detect complexity and preserve HTML
+
+    Raises TableComplexityException when encountering:
+    - colspan > 1
+    - rowspan > 1
+    - Multiple tbody sections
+    """
+
+    def __init__(self, **options):
+        super().__init__(**options)
+        self._tbody_count = 0
+
+    def convert_td(self, el: "Tag", text: str, parent_tags: set[str]) -> str:
+        self._check_cell_complexity(el)
+        return super().convert_td(el, text, parent_tags)  # type: ignore[attr-defined]
+
+    def convert_th(self, el: "Tag", text: str, parent_tags: set[str]) -> str:
+        self._check_cell_complexity(el)
+        return super().convert_th(el, text, parent_tags)  # type: ignore[attr-defined]
+
+    def convert_table(self, el: "Tag", text: str, parent_tags: set[str]) -> str:
+        self._tbody_count = len(el.find_all("tbody", recursive=False))
+        if self._tbody_count > 1:
+            raise _TableComplexityException(
+                f"Table has {self._tbody_count} tbody sections (GFM only supports 1)"
+            )
+        return super().convert_table(el, text, parent_tags)  # type: ignore[attr-defined]
+
+    def _check_cell_complexity(self, el: "Tag") -> None:
+        colspan = el.get("colspan", "1")
+        rowspan = el.get("rowspan", "1")
+
+        try:
+            colspan_str = str(colspan) if colspan else "1"
+            rowspan_str = str(rowspan) if rowspan else "1"
+
+            if int(colspan_str) > 1:
+                raise _TableComplexityException(
+                    f"Table has colspan={colspan_str} (GFM doesn't support colspan)"
+                )
+            if int(rowspan_str) > 1:
+                raise _TableComplexityException(
+                    f"Table has rowspan={rowspan_str} (GFM doesn't support rowspan)"
+                )
+        except ValueError as error:
+            raise _TableComplexityException(
+                "Table has invalid colspan/rowspan values"
+            ) from error
+
+
+def render_table_content(html_string: str) -> str:
+    try:
+        converter = _GFMTableConverter(heading_style="ATX")
+        gfm_table = converter.convert(html_string).strip()
+        return gfm_table
+    except _TableComplexityException:
+        return html_string

poetry.lock

@@ -40,6 +40,7 @@ doc-page-extractor = "==1.0.12"
 epub-generator = "==0.1.7"
 pylatexenc = "^2.10"
 pyahocorasick = "^2.2.0"
+markdownify = "^1.2.2"
 
 [tool.poetry.group.dev.dependencies]
 pylint = "^3.3.7"