Interface QueryableNode

crates/css_ast/src/visit/mod.rs:125–149

Marker trait for AST nodes that can be queried with selectors. Implemented by `#[derive(Visitable)]` for queryable nodes, and manually for nodes with `get_property` overrides (named at-rules, declarations). Not part of the `Visit` public API - visitors receive a [`VisitNode`] instead.

/// with `get_property` overrides (named at-rules, declarations).
/// Not part of the `Visit` public API - visitors receive a [`VisitNode`] instead.
pub(crate) trait QueryableNode: ToSpan + NodeWithMetadata<CssMetadata> {
	/// Unique identifier for this node type.
	const NODE_ID: NodeId;

	/// Returns a cursor for the given property kind, if the node has that property.
	/// Used by attribute selectors to extract values from nodes.
	///
	/// For `PropertyKind::Name`, returns a cursor to the node's name (e.g., property
	/// name for declarations, animation name for `@keyframes`).
	fn get_property(&self, _kind: PropertyKind) -> Option<Cursor> {
		None
	}

	/// Builds the [`VisitNode`] passed to every `Visit` callback for this node.
	///
	/// `subtree_metadata` (eager) uses `metadata()` (self + subtree) so the prune gate can
	/// reject whole subtrees; `self_metadata`/properties are deferred to `&dyn` accessors so
	/// they only cost anything when a visitor actually reads them.
	fn visit_node(&self) -> VisitNode<'_>
	where
		Self: Sized,
	{
		VisitNode::new(self.to_span(), Self::NODE_ID, self.metadata(), self)
	}
}

/// Blanket bridge so any [`QueryableNode`] can be held as a `&dyn` in [`VisitNode`].
impl<T: QueryableNode> QueryNodeData for T {