chore: reduce component overhead (#3)

Reviewed-on: reya/gpui-native-kit#3

crates/data/src/tree.rs

@@ -166,14 +166,49 @@ impl RenderOnce for Tree {
             .clone()
             .unwrap_or_else(|| SharedString::from(self.id.to_string()));
 
+        let sibling_sets: Vec<(usize, usize)> = {
+            let mut sets = vec![(0usize, 0usize); items.len()];
+            let mut start = 0usize;
+
+            while start < items.len() {
+                let depth = items[start].depth;
+
+                let mut end = start + 1;
+                while end < items.len() && items[end].depth > depth {
+                    end += 1;
+                }
+
+                let mut position = 0usize;
+                for index in start..end {
+                    if items[index].depth == depth {
+                        position += 1;
+                        sets[index] = (position, 0);
+                    }
+                }
+
+                for index in start..end {
+                    if items[index].depth == depth {
+                        sets[index].1 = position;
+                    }
+                }
+
+                start = end;
+            }
+
+            sets
+        };
+
         let rows: Vec<AnyElement> = items
             .iter()
             .enumerate()
             .map(|(index, _item)| {
+                let (position_in_set, size_of_set) = sibling_sets[index];
                 render_row(
                     cx,
-                    &items,
+                    &items[index],
                     index,
+                    position_in_set,
+                    size_of_set,
                     self.selected == Some(index),
                     &self.on_change,
                     &self.on_disclosure,
@@ -228,21 +263,21 @@ impl RenderOnce for Tree {
     }
 }
 
+#[allow(clippy::too_many_arguments)]
 fn render_row(
     cx: &App,
-    items: &[TreeItem],
+    item: &TreeItem,
     index: usize,
+    position_in_set: usize,
+    size_of_set: usize,
     selected: bool,
     on_change: &Option<ChangeHandler>,
     on_disclosure: &Option<DisclosureHandler>,
     focus: &FocusHandle,
 ) -> AnyElement {
     let theme = cx.theme();
-    let item = &items[index];
-    let count = items.len();
     let label_color = selectable_label_color(cx, selected, item.disabled);
     let disabled = item.disabled;
-
     // One indent step per depth level, on the theme's horizontal padding.
     let indent = theme.sizes.medium.padding_x * (item.depth as f32 + 1.0);
 
@@ -258,7 +293,8 @@ fn render_row(
         .role(Role::TreeItem)
         .aria_selected(selected)
         .aria_level(item.depth + 1)
-        .aria_size_of_set(count)
+        .aria_position_in_set(position_in_set)
+        .aria_size_of_set(size_of_set)
         .when(item.expandable, |row| row.aria_expanded(item.expanded))
         .map(|row| paint_selectable_row(cx, row, selected, disabled))
         .when(!disabled, |row| {