From 0f51f4208dfddb05752da815fc0efc18fd163abe Mon Sep 17 00:00:00 2001
From: AA Turner <9087854+AA-Turner@users.noreply.github.com>
Date: Tue, 20 Apr 2021 03:40:22 +0100
Subject: [PATCH] Add extension setup and maths & settings overrides

---
 pep_sphinx_extensions/__init__.py | 45 +++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 pep_sphinx_extensions/__init__.py

diff --git a/pep_sphinx_extensions/__init__.py b/pep_sphinx_extensions/__init__.py
new file mode 100644
index 00000000000..d623f034ad5
--- /dev/null
+++ b/pep_sphinx_extensions/__init__.py
@@ -0,0 +1,45 @@
+"""Sphinx extensions for performant PEP processing"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from sphinx.environment import default_settings
+from docutils.writers.html5_polyglot import HTMLTranslator
+
+from pep_sphinx_extensions.pep_processor.html import pep_html_translator
+from pep_sphinx_extensions.pep_processor.parsing import pep_parser
+from pep_sphinx_extensions.pep_processor.parsing import pep_role
+
+if TYPE_CHECKING:
+    from sphinx.application import Sphinx
+
+# Monkeypatch sphinx.environment.default_settings as Sphinx doesn't allow custom settings or Readers
+default_settings |= {
+    "pep_references": True,
+    "rfc_references": True,
+    "pep_base_url": "",
+    "pep_file_url_template": "pep-%04d.html",
+    "_disable_config": True,  # disable using docutils.conf whilst running both PEP generators
+}
+
+
+def _depart_maths():
+    pass  # No-op callable for the type checker
+
+
+def setup(app: Sphinx) -> dict[str, bool]:
+    """Initialize Sphinx extension."""
+
+    # Register plugin logic
+    app.add_source_parser(pep_parser.PEPParser)  # Add PEP transforms
+    app.add_role("pep", pep_role.PEPRole(), override=True)  # Transform PEP references to links
+    app.set_translator("html", pep_html_translator.PEPTranslator)  # Docutils Node Visitor overrides
+
+    # Mathematics rendering
+    inline_maths = HTMLTranslator.visit_math, _depart_maths
+    block_maths = HTMLTranslator.visit_math_block, _depart_maths
+    app.add_html_math_renderer("maths_to_html", inline_maths, block_maths)  # Render maths to HTML
+
+    # Parallel safety: https://www.sphinx-doc.org/en/master/extdev/index.html#extension-metadata
+    return {"parallel_read_safe": True, "parallel_write_safe": True}