docs: add bootstrap extension

To get Sphinx and Bootstrap to work well together, we need to massage
the output from Sphinx a bit. This adds an extension to do such changes,
based on work from here:

https://github.com/pydata/pydata-sphinx-theme

...However, because we don't ship as an external theme, we can't just do
things as a part of __init__.py, so instead we register an extension
that does the heavy lifting for us.

Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8399>

docs/_exts/bootstrap.py

@@ -0,0 +1,108 @@
+# BSD 3-Clause License
+#
+# Copyright (c) 2018, pandas
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+#
+# * Neither the name of the copyright holder nor the names of its
+#   contributors may be used to endorse or promote products derived from
+#   this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# Based on https://github.com/pydata/pydata-sphinx-theme
+
+from packaging.version import Version
+
+from docutils import nodes
+
+import sphinx
+from sphinx.ext.autosummary import autosummary_table
+
+import types
+
+class BootstrapHTML5TranslatorMixin:
+    def __init__(self, *args, **kwds):
+        super().__init__(*args, **kwds)
+        self.settings.table_style = "table"
+
+    def starttag(self, *args, **kwargs):
+        """ensure an aria-level is set for any heading role"""
+        if kwargs.get("ROLE") == "heading" and "ARIA-LEVEL" not in kwargs:
+            kwargs["ARIA-LEVEL"] = "2"
+        return super().starttag(*args, **kwargs)
+
+    def visit_table(self, node):
+        # init the attributes
+        atts = {}
+
+        if Version(sphinx.__version__) < Version("4.3"):
+            self._table_row_index = 0
+        else:
+            self._table_row_indices.append(0)
+
+        # get the classes
+        classes = [cls.strip(" \t\n") for cls in self.settings.table_style.split(",")]
+
+        # we're looking at the 'real_table', which is wrapped by an autosummary
+        if isinstance(node.parent, autosummary_table):
+            classes += ["autosummary"]
+
+        # add the width if set in a style attribute
+        if "width" in node:
+            atts["style"] = f'width: {node["width"]}'
+
+        # add specific class if align is set
+        if "align" in node:
+            classes.append(f'table-{node["align"]}')
+
+        tag = self.starttag(node, "table", CLASS=" ".join(classes), **atts)
+        self.body.append(tag)
+
+def setup_translators(app):
+    if not app.registry.translators.items():
+        translator = types.new_class(
+            "BootstrapHTML5Translator",
+            (
+                BootstrapHTML5TranslatorMixin,
+                app.builder.default_translator_class,
+            ),
+            {},
+        )
+        app.set_translator(app.builder.name, translator, override=True)
+    else:
+        for name, klass in app.registry.translators.items():
+            if app.builder.format != "html":
+                # Skip translators that are not HTML
+                continue
+
+            translator = types.new_class(
+                "BootstrapHTML5Translator",
+                (
+                    BootstrapHTML5TranslatorMixin,
+                    klass,
+                ),
+                {},
+            )
+            app.set_translator(name, translator, override=True)
+
+def setup(app):
+    app.connect("builder-inited", setup_translators)