Flexible declaration styling

CHANGES

@@ -7,12 +7,17 @@ Dependencies
 Incompatible changes
 --------------------
 
+* #9023: Change the CSS classes on :rst:role:`cpp:expr` and
+  :rst:role:`cpp:texpr`.
+
 Deprecated
 ----------
 
 Features added
 --------------
 
+* #9023: More CSS classes on domain descriptions, see :ref:`nodes` for details.
+
 Bugs fixed
 ----------
 

doc/extdev/nodes.rst

@@ -8,18 +8,32 @@ Doctree node classes added by Sphinx
 Nodes for domain-specific object descriptions
 ---------------------------------------------
 
+Top-level nodes
+...............
+
+These nodes form the top-most levels of object descriptions.
+
 .. autoclass:: desc
 .. autoclass:: desc_signature
 .. autoclass:: desc_signature_line
+.. autoclass:: desc_content
+.. autoclass:: desc_inline
+
+Nodes for high-level structure in signatures
+............................................
+
+These nodes occur in in non-multiline :py:class:`desc_signature` nodes
+and in :py:class:`desc_signature_line` nodes.
+
+.. autoclass:: desc_name
 .. autoclass:: desc_addname
+
 .. autoclass:: desc_type
 .. autoclass:: desc_returns
-.. autoclass:: desc_name
 .. autoclass:: desc_parameterlist
 .. autoclass:: desc_parameter
 .. autoclass:: desc_optional
 .. autoclass:: desc_annotation
-.. autoclass:: desc_content
 
 New admonition-like constructs
 ------------------------------

sphinx/addnodes.py

@@ -115,25 +115,53 @@ def extract_original_messages(self) -> List[str]:
         return messages
 
 
-# domain-specific object descriptions (class, function etc.)
+#############################################################
+# Domain-specific object descriptions (class, function etc.)
+#############################################################
+
+class _desc_classes_injector(nodes.Element, not_smartquotable):
+    """Helper base class for injecting a fixes list of classes.
+
+    Use as the first base class.
+    """
+
+    classes: List[str] = []
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        super().__init__(*args, **kwargs)
+        self['classes'].extend(self.classes)
+
+
+# Top-level nodes
+#################
 
 class desc(nodes.Admonition, nodes.Element):
-    """Node for object descriptions.
+    """Node for a list of object signatures and a common description of them.
 
-    This node is similar to a "definition list" with one definition.  It
-    contains one or more ``desc_signature`` and a ``desc_content``.
+    Contains one or more :py:class:`desc_signature` nodes
+    and then a single :py:class:`desc_content` node.
+
+    This node always has two classes:
+
+    - The name of the domain it belongs to, e.g., ``py`` or ``cpp``.
+    - The name of the object type in the domain, e.g., ``function``.
     """
 
+    # TODO: can we introduce a constructor
+    #  that forces the specification of the domain and objtyp?
 
-class desc_signature(nodes.Part, nodes.Inline, nodes.TextElement):
-    """Node for object signatures.
 
-    The "term" part of the custom Sphinx definition list.
+class desc_signature(_desc_classes_injector, nodes.Part, nodes.Inline, nodes.TextElement):
+    """Node for a single object signature.
 
-    As default the signature is a single line signature,
-    but set ``is_multiline = True`` to describe a multi-line signature.
-    In that case all child nodes must be ``desc_signature_line`` nodes.
+    As default the signature is a single-line signature.
+    Set ``is_multiline = True`` to describe a multi-line signature.
+    In that case all child nodes must be :py:class:`desc_signature_line` nodes.
+
+    This node always has the classes ``sig``, ``sig-object``, and the domain it belongs to.
     """
+    # Note: the domain name is being added through a post-transform DescSigAddDomainAsClass
+    classes = ['sig', 'sig-object']
 
     @property
     def child_text_separator(self):
@@ -144,18 +172,63 @@ def child_text_separator(self):
 
 
 class desc_signature_line(nodes.Part, nodes.Inline, nodes.FixedTextElement):
-    """Node for a line in a multi-line object signatures.
+    """Node for a line in a multi-line object signature.
 
-    It should only be used in a ``desc_signature`` with ``is_multiline`` set.
+    It should only be used as a child of a :py:class:`desc_signature`
+    with ``is_multiline`` set to ``True``.
     Set ``add_permalink = True`` for the line that should get the permalink.
     """
     sphinx_line_type = ''
 
 
+class desc_content(nodes.General, nodes.Element):
+    """Node for object description content.
+
+    Must be the last child node in a :py:class:`desc` node.
+    """
+
+
+class desc_inline(_desc_classes_injector, nodes.Inline, nodes.TextElement):
+    """Node for a signature fragment in inline text.
+
+    This is for example used for roles like :rst:role:`cpp:expr`.
+
+    This node always has the classes ``sig``, ``sig-inline``,
+    and the name of the domain it belongs to.
+    """
+    classes = ['sig', 'sig-inline']
+
+    def __init__(self, domain: str, *args: Any, **kwargs: Any) -> None:
+        super().__init__(*args, **kwargs)
+        self['classes'].append(domain)
+
+
+# Nodes for high-level structure in signatures
+##############################################
+
 # nodes to use within a desc_signature or desc_signature_line
 
-class desc_addname(nodes.Part, nodes.Inline, nodes.FixedTextElement):
-    """Node for additional name parts (module name, class name)."""
+class desc_name(_desc_classes_injector, nodes.Part, nodes.Inline, nodes.FixedTextElement):
+    """Node for the main object name.
+
+    For example, in the declaration of a Python class ``MyModule.MyClass``,
+    the main name is ``MyClass``.
+
+    This node always has the class ``sig-name``.
+    """
+    classes = ['sig-name', 'descname']  # 'descname' is for backwards compatibility
+
+
+class desc_addname(_desc_classes_injector, nodes.Part, nodes.Inline, nodes.FixedTextElement):
+    """Node for additional name parts for an object.
+
+    For example, in the declaration of a Python class ``MyModule.MyClass``,
+    the additional name part is ``MyModule.``.
+
+    This node always has the class ``sig-prename``.
+    """
+    # 'descclassname' is for backwards compatibility
+    classes = ['sig-prename', 'descclassname']
 
 
 # compatibility alias
@@ -168,14 +241,11 @@ class desc_type(nodes.Part, nodes.Inline, nodes.FixedTextElement):
 
 class desc_returns(desc_type):
     """Node for a "returns" annotation (a la -> in Python)."""
+
     def astext(self) -> str:
         return ' -> ' + super().astext()
 
 
-class desc_name(nodes.Part, nodes.Inline, nodes.FixedTextElement):
-    """Node for the main object name."""
-
-
 class desc_parameterlist(nodes.Part, nodes.Inline, nodes.FixedTextElement):
     """Node for a general parameter list."""
     child_text_separator = ', '
@@ -200,14 +270,14 @@ class desc_annotation(nodes.Part, nodes.Inline, nodes.FixedTextElement):
     """Node for signature annotations (not Python 3-style annotations)."""
 
 
-class desc_content(nodes.General, nodes.Element):
-    """Node for object description content.
-
-    This is the "definition" part of the custom Sphinx definition list.
-    """
+# Leaf nodes for markup of text fragments
+#########################################
 
+# Signature text elements, generally translated to node.inline
+# in SigElementFallbackTransform.
+# When adding a new one, add it to SIG_ELEMENTS.
 
-class desc_sig_element(nodes.inline):
+class desc_sig_element(nodes.inline, _desc_classes_injector):
     """Common parent class of nodes for inline text of a signature."""
     classes: List[str] = []
 
@@ -217,8 +287,20 @@ def __init__(self, rawsource: str = '', text: str = '',
         self['classes'].extend(self.classes)
 
 
+# to not reinvent the wheel, the classes in the following desc_sig classes
+# are based on those used in Pygments
+
+class desc_sig_space(desc_sig_element):
+    """Node for a space in a signature."""
+    classes = ["w"]
+
+    def __init__(self, rawsource: str = '', text: str = ' ',
+                 *children: Element, **attributes: Any) -> None:
+        super().__init__(rawsource, text, *children, **attributes)
+
+
 class desc_sig_name(desc_sig_element):
-    """Node for a name in a signature."""
+    """Node for an identifier in a signature."""
     classes = ["n"]
 
 
@@ -228,10 +310,44 @@ class desc_sig_operator(desc_sig_element):
 
 
 class desc_sig_punctuation(desc_sig_element):
-    """Node for a punctuation in a signature."""
+    """Node for punctuation in a signature."""
     classes = ["p"]
 
 
+class desc_sig_keyword(desc_sig_element):
+    """Node for a general keyword in a signature."""
+    classes = ["k"]
+
+
+class desc_sig_keyword_type(desc_sig_element):
+    """Node for a keyword which is a built-in type in a signature."""
+    classes = ["kt"]
+
+
+class desc_sig_literal_number(desc_sig_element):
+    """Node for a numeric literal in a signature."""
+    classes = ["m"]
+
+
+class desc_sig_literal_string(desc_sig_element):
+    """Node for a string literal in a signature."""
+    classes = ["s"]
+
+
+class desc_sig_literal_char(desc_sig_element):
+    """Node for a character literal in a signature."""
+    classes = ["sc"]
+
+
+SIG_ELEMENTS = [desc_sig_space,
+                desc_sig_name,
+                desc_sig_operator,
+                desc_sig_punctuation,
+                desc_sig_keyword, desc_sig_keyword_type,
+                desc_sig_literal_number, desc_sig_literal_string, desc_sig_literal_char]
+
+
+###############################################################
 # new admonition-like constructs
 
 class versionmodified(nodes.Admonition, nodes.TextElement):
@@ -336,6 +452,7 @@ class pending_xref(nodes.Inline, nodes.Element):
     These nodes are resolved before writing output, in
     BuildEnvironment.resolve_references.
     """
+    child_text_separator = ''
 
 
 class pending_xref_condition(nodes.Inline, nodes.TextElement):
@@ -412,21 +529,25 @@ class manpage(nodes.Inline, nodes.FixedTextElement):
 
 def setup(app: "Sphinx") -> Dict[str, Any]:
     app.add_node(toctree)
+
     app.add_node(desc)
     app.add_node(desc_signature)
     app.add_node(desc_signature_line)
+    app.add_node(desc_content)
+    app.add_node(desc_inline)
+
+    app.add_node(desc_name)
     app.add_node(desc_addname)
     app.add_node(desc_type)
     app.add_node(desc_returns)
-    app.add_node(desc_name)
     app.add_node(desc_parameterlist)
     app.add_node(desc_parameter)
     app.add_node(desc_optional)
     app.add_node(desc_annotation)
-    app.add_node(desc_content)
-    app.add_node(desc_sig_name)
-    app.add_node(desc_sig_operator)
-    app.add_node(desc_sig_punctuation)
+
+    for n in SIG_ELEMENTS:
+        app.add_node(n)
+
     app.add_node(versionmodified)
     app.add_node(seealso)
     app.add_node(productionlist)

sphinx/directives/__init__.py

@@ -172,6 +172,7 @@ def run(self) -> List[Node]:
         node['noindex'] = noindex = ('noindex' in self.options)
         if self.domain:
             node['classes'].append(self.domain)
+        node['classes'].append(node['objtype'])
 
         self.names: List[T] = []
         signatures = self.get_signatures()