Override generation of id & href attributes for API documentation

This will replace dots with underscores in qualified names of Python modules & functions (e.g. `mypackage.mymodule.myfunc`), allowing ScrollSpy to identify these tags as navigation targets.

Addresses #1207 and fixes #1026

src/pydata_sphinx_theme/translator.py

@@ -1,11 +1,13 @@
 """
 A custom Sphinx HTML Translator for Bootstrap layout
 """
+from functools import partial
 from packaging.version import Version
 
 import sphinx
 from sphinx.util import logging
 from sphinx.ext.autosummary import autosummary_table
+from docutils.nodes import Element
 
 logger = logging.getLogger(__name__)
 
@@ -58,3 +60,72 @@ def visit_table(self, node):
 
         tag = self.starttag(node, "table", CLASS=" ".join(classes), **atts)
         self.body.append(tag)
+
+    def visit_section(self, node):
+        """Handle section nodes, parsing ``ids`` to replace dots with underscores.
+
+        This will modify the ``id`` of HTML ``<section>`` tags, e.g. where Python modules are documented.
+        Replacing dots with underscores allows the tags to be recognized as navigation targets by ScrollSpy.
+        """
+        if "ids" in node:
+            node["ids"] = [id_.replace(".", "_") for id_ in node["ids"]]
+        super().visit_section(node)
+
+    def visit_desc_signature(self, node):
+        """Handle function & method signature nodes, parsing ``ids`` to replace dots with underscores.
+
+        This will modify the ``id`` attribute of HTML ``<dt>`` & ``<dd>`` tags, where Python functions are documented.
+        Replacing dots with underscores allows the tags to be recognized as navigation targets by ScrollSpy.
+        """
+        if "ids" in node:
+            ids = node["ids"]
+            for i, id_ in enumerate(ids):
+                ids[i] = id_.replace(".", "_")
+        super().visit_desc_signature(node)
+
+    def visit_reference(self, node):
+        """Handle reference nodes, parsing ``refuri`` and ``anchorname`` attributes to replace dots with underscores.
+
+        This will modify the ``href`` attribute of internal HTML ``<a>`` tags, e.g. the sidebar navigation links.
+        """
+        try:
+            # We are only interested in internal anchor references
+            internal, anchorname = node["internal"], node["anchorname"]
+            if internal and anchorname.startswith("#") and "." in anchorname:
+                # Get the root node of the current document
+                document = self.builder.env.get_doctree(self.builder.current_docname)
+
+                # Get the target anchor ID
+                target_id = anchorname.lstrip("#")
+                sanitized_id = target_id.replace(".", "_")
+                # Update the node `href`
+                node["refuri"] = node["anchorname"] = "#" + sanitized_id
+
+                # Define a search condition to find the target node by ID
+                def find_target(search_id, node):
+                    return (
+                        isinstance(node, Element)
+                        and ("ids" in node)
+                        and (search_id in node["ids"])
+                    )
+
+                # NOTE: Replacing with underscores creates the possibility for conflicting references
+                # We should check for these and warn the user if any are found
+                if any(document.traverse(condition=partial(find_target, sanitized_id))):
+                    logger.warning(
+                        f'Sanitized reference "{sanitized_id}" for "{target_id}" conflicts with an existing reference!'
+                    )
+
+                # Find nodes with the given ID (there should only be one)
+                targets = document.traverse(condition=partial(find_target, target_id))
+                # Replace dots with underscores in the target node ID
+                for target in targets:
+                    # NOTE: By itself, modifying the target `ids` here seems to be insufficient, however it helps
+                    # ensure that the reference `refuri` and target `ids` remain consistent during the build process
+                    target["ids"] = [
+                        sanitized_id if id_ == target_id else id_
+                        for id_ in target["ids"]
+                    ]
+        except KeyError:
+            pass
+        super().visit_reference(node)