Remove has_equations from the mathematics domain

CHANGES.rst

@@ -9,6 +9,10 @@ Dependencies
 Incompatible changes
 --------------------
 
+* #13044: Remove the internal and undocumented ``has_equations`` data and
+  :py:meth:`!has_equations` method from the :py:class:`!MathDomain`` domain.
+  Patch by Adam Turner.
+
 Deprecated
 ----------
 

sphinx/builders/html/__init__.py

@@ -656,6 +656,7 @@ def write_doc(self, docname: str, doctree: nodes.document) -> None:
         metatags = self.docwriter.clean_meta
 
         ctx = self.get_doc_context(docname, body, metatags)
+        ctx['_has_equations'] = self.docwriter._has_equations
         self.handle_page(docname, ctx, event_arg=doctree)
 
     def write_doc_serialized(self, docname: str, doctree: nodes.document) -> None:

sphinx/domains/math.py

@@ -41,7 +41,6 @@ class MathDomain(Domain):
 
     initial_data: dict[str, Any] = {
         'objects': {},  # labelid -> (docname, eqno)
-        'has_equations': {},  # docname -> bool
     }
     dangling_warnings = {
         'eq': 'equation not found: %(target)s',
@@ -71,28 +70,16 @@ def get_equation_number_for(self, labelid: str) -> int | None:
         else:
             return None
 
-    def process_doc(self, env: BuildEnvironment, docname: str,
-                    document: nodes.document) -> None:
-        def math_node(node: Node) -> bool:
-            return isinstance(node, nodes.math | nodes.math_block)
-
-        self.data['has_equations'][docname] = any(document.findall(math_node))
-
     def clear_doc(self, docname: str) -> None:
         for equation_id, (doc, _eqno) in list(self.equations.items()):
             if doc == docname:
                 del self.equations[equation_id]
 
-        self.data['has_equations'].pop(docname, None)
-
     def merge_domaindata(self, docnames: Set[str], otherdata: dict[str, Any]) -> None:
         for labelid, (doc, eqno) in otherdata['objects'].items():
             if doc in docnames:
                 self.equations[labelid] = (doc, eqno)
 
-        for docname in docnames:
-            self.data['has_equations'][docname] = otherdata['has_equations'][docname]
-
     def resolve_xref(self, env: BuildEnvironment, fromdocname: str, builder: Builder,
                      typ: str, target: str, node: pending_xref, contnode: Element,
                      ) -> Element | None:
@@ -136,15 +123,6 @@ def resolve_any_xref(self, env: BuildEnvironment, fromdocname: str, builder: Bui
     def get_objects(self) -> Iterable[tuple[str, str, str, str, str, int]]:
         return []
 
-    def has_equations(self, docname: str | None = None) -> bool:
-        if not docname:
-            return any(self.data['has_equations'].values())
-
-        return (
-            self.data['has_equations'].get(docname, False)
-            or any(map(self.has_equations, self.env.toctree_includes.get(docname, ())))
-        )
-
 
 def setup(app: Sphinx) -> ExtensionMetadata:
     app.add_domain(MathDomain)

sphinx/ext/mathjax.py

@@ -81,9 +81,8 @@ def install_mathjax(app: Sphinx, pagename: str, templatename: str, context: dict
         msg = 'mathjax_path config value must be set for the mathjax extension to work'
         raise ExtensionError(msg)
 
-    domain = app.env.domains.math_domain
     builder = cast(StandaloneHTMLBuilder, app.builder)
-    if app.registry.html_assets_policy == 'always' or domain.has_equations(pagename):
+    if app.registry.html_assets_policy == 'always' or context.get('_has_equations'):
         # Enable mathjax only if equations exists
         if app.config.mathjax2_config:
             if app.config.mathjax_path == MATHJAX_URL:

sphinx/writers/html.py

@@ -27,6 +27,7 @@ class HTMLWriter(Writer):  # type: ignore[misc]
     def __init__(self, builder: StandaloneHTMLBuilder) -> None:
         super().__init__()
         self.builder = builder
+        self._has_equations: bool = False
 
     def translate(self) -> None:
         # sadly, this is mostly copied from parent class
@@ -57,3 +58,4 @@ def translate(self) -> None:
         ):
             setattr(self, attr, getattr(visitor, attr, None))
         self.clean_meta = ''.join(self.visitor.meta[2:])
+        self._has_equations = getattr(visitor, '_has_equations', False)

sphinx/writers/html5.py

@@ -66,6 +66,7 @@ def __init__(self, document: nodes.document, builder: Builder) -> None:
         self._table_row_indices = [0]
         self._fieldlist_row_indices = [0]
         self.required_params_left = 0
+        self._has_equations: bool = False
 
     def visit_start_of_file(self, node: Element) -> None:
         # only occurs in the single-file builder
@@ -958,6 +959,8 @@ def visit_field(self, node: Element) -> None:
             node['classes'].append('field-odd')
 
     def visit_math(self, node: Element, math_env: str = '') -> None:
+        self._has_equations = True
+
         # see validate_math_renderer
         name: str = self.builder.math_renderer_name  # type: ignore[assignment]
         visit, _ = self.builder.app.registry.html_inline_math_renderers[name]
@@ -971,6 +974,8 @@ def depart_math(self, node: Element, math_env: str = '') -> None:
             depart(self, node)
 
     def visit_math_block(self, node: Element, math_env: str = '') -> None:
+        self._has_equations = True
+
         # see validate_math_renderer
         name: str = self.builder.math_renderer_name  # type: ignore[assignment]
         visit, _ = self.builder.app.registry.html_block_math_renderers[name]