Reuse anonymous blocks for complex inline layouts

packages/dom/src/document.rs

@@ -310,6 +310,21 @@ impl Document {
         new_node_id
     }
 
+    /// Used for cleaning invalid anonymous blocks
+    fn clean_anonymous_blocks(&mut self, node_id: usize) {
+        let children = &mut self.nodes[node_id].children.clone();
+        for child_id in children.iter() {
+            self.clean_anonymous_blocks(*child_id);
+        }
+
+        let node = &mut self.nodes[node_id];
+        node.anonymous_block_id = None;
+        if let Some(anonymous_block_id) = node.anonymous_block_id {
+            // Removing does pattern matching so removing the same node multiple times is ok
+            self.remove_node(anonymous_block_id);
+        }
+    }
+
     pub fn insert_before(&mut self, node_id: usize, inserted_node_ids: &[usize]) {
         // let count = inserted_node_ids.len();
 
@@ -319,6 +334,7 @@ impl Document {
         let node_child_idx = node.child_idx;
 
         let parent_id = node.parent.unwrap();
+        self.clean_anonymous_blocks(parent_id);
         let parent = &mut self.nodes[parent_id];
 
         // Mark the node's parent as changed.
@@ -347,6 +363,7 @@ impl Document {
         let node = &self.nodes[node_id];
         // let node_child_idx = node.child_idx;
         let parent_id = node.parent.unwrap();
+        self.clean_anonymous_blocks(parent_id);
         let parent = &mut self.nodes[parent_id];
 
         let mut children = std::mem::take(&mut parent.children);
@@ -383,6 +400,7 @@ impl Document {
         if let Some(Node {
             mut child_idx,
             parent: Some(parent_id),
+            anonymous_block_id,
             ..
         }) = node
         {
@@ -399,7 +417,20 @@ impl Document {
                 child_idx += 1;
             }
 
-            self.nodes[parent_id].children = children;
+            // remove unneeded anonymous blocks
+            if let Some(anonymous_block_id) = anonymous_block_id {
+                let is_block_used = children.iter().any(|child_id| {
+                    let child = self.get_node(*child_id);
+                    matches!(child, Some(child) if child.anonymous_block_id == Some(anonymous_block_id))
+                });
+
+                self.nodes[parent_id].children = children;
+                if !is_block_used {
+                    self.remove_node(anonymous_block_id);
+                }
+            } else {
+                self.nodes[parent_id].children = children;
+            }
         }
 
         node

packages/dom/src/layout/construct.rs

@@ -235,6 +235,13 @@ fn collect_complex_layout_children(
         else if needs_wrap(child_node_kind, display_outside) {
             use style::selector_parser::PseudoElement;
 
+            // TODO: once let chaining lends in stable, make nicer
+            if anonymous_block_id.is_none() {
+                if let Some(child) = doc.get_node(child_id) {
+                    *anonymous_block_id = child.anonymous_block_id;
+                }
+            }
+
             if anonymous_block_id.is_none() {
                 const NAME: QualName = QualName {
                     prefix: None,
@@ -246,6 +253,9 @@ fn collect_complex_layout_children(
                     Vec::new(),
                 )));
 
+                let child = doc.get_node_mut(child_id).unwrap();
+                child.anonymous_block_id = Some(node_id);
+
                 // Set style data
                 let parent_style = doc.nodes[container_node_id].primary_styles().unwrap();
                 let read_guard = doc.guard.read();
@@ -262,6 +272,9 @@ fn collect_complex_layout_children(
 
                 layout_children.push(node_id);
                 *anonymous_block_id = Some(node_id);
+
+                #[cfg(feature = "tracing")]
+                tracing::info!("Created anonymous block container with id {}", node_id);
             }
 
             doc.nodes[anonymous_block_id.unwrap()]

packages/dom/src/node.rs

@@ -53,6 +53,10 @@ pub struct Node {
     pub child_idx: usize,
     // What are our children?
     pub children: Vec<usize>,
+    // What anonymous block are we a part of
+    // Changing order of nodes requires unsetting
+    // using the "clean_anonymous_blocks" method with parent_id
+    pub anonymous_block_id: Option<usize>,
     /// A separate child list that includes anonymous collections of inline elements
     pub layout_children: RefCell<Option<Vec<usize>>>,
 
@@ -90,6 +94,7 @@ impl Node {
             id,
             parent: None,
             children: vec![],
+            anonymous_block_id: None,
             layout_children: RefCell::new(None),
             child_idx: 0,