feat: add support for tree sections

packages/@react-aria/collections/src/useCachedChildren.ts

@@ -45,11 +45,11 @@ export function useCachedChildren<T extends object>(props: CachedChildrenOptions
           rendered = children(item);
           // @ts-ignore
           let key = rendered.props.id ?? item.key ?? item.id;
-           
+
           if (key == null) {
             throw new Error('Could not determine key for item');
           }
-           
+
           if (idScope) {
             key = idScope + ':' + key;
           }

packages/@react-aria/dnd/src/DropTargetKeyboardNavigation.ts

@@ -59,6 +59,10 @@ function nextDropTarget(
       nextKey = keyboardDelegate.getKeyBelow?.(target.key);
     }
     let nextCollectionKey = collection.getKeyAfter(target.key);
+    let nextCollectionNode = nextCollectionKey && collection.getItem(nextCollectionKey);
+    if (nextCollectionNode && nextCollectionNode.type === 'content') {
+      nextCollectionKey = nextCollectionKey ? collection.getKeyAfter(nextCollectionKey) : null;
+    }
 
     // If the keyboard delegate did not move to the next key in the collection,
     // jump to that key with the same drop position. Otherwise, try the other
@@ -100,7 +104,7 @@ function nextDropTarget(
       }
       case 'after': {
         // If this is the last sibling in a level, traverse to the parent.
-        let targetNode = collection.getItem(target.key);        
+        let targetNode = collection.getItem(target.key);
         if (targetNode && targetNode.nextKey == null && targetNode.parentKey != null) {
           // If the parent item has an item after it, use the "before" position.
           let parentNode = collection.getItem(targetNode.parentKey);

packages/@react-aria/gridlist/package.json

@@ -26,6 +26,7 @@
     "url": "https://github.com/adobe/react-spectrum"
   },
   "dependencies": {
+    "@react-aria/collections": "^3.0.0",
     "@react-aria/focus": "^3.21.2",
     "@react-aria/grid": "^3.14.5",
     "@react-aria/i18n": "^3.12.13",

packages/@react-aria/gridlist/src/useGridListItem.ts

@@ -11,7 +11,8 @@
  */
 
 import {chain, getScrollParent, mergeProps, scrollIntoViewport, useSlotId, useSyntheticLinkProps} from '@react-aria/utils';
-import {DOMAttributes, FocusableElement, Key, RefObject, Node as RSNode} from '@react-types/shared';
+import {Collection, DOMAttributes, FocusableElement, Key, RefObject, Node as RSNode} from '@react-types/shared';
+import {CollectionNode} from '@react-aria/collections';
 import {focusSafely, getFocusableTreeWalker} from '@react-aria/focus';
 import {getRowId, listMap} from './utils';
 import {HTMLAttributes, KeyboardEvent as ReactKeyboardEvent, useRef} from 'react';
@@ -100,11 +101,11 @@ export function useGridListItem<T>(props: AriaGridListItemOptions, state: ListSt
 
     let isExpanded = hasChildRows ? state.expandedKeys.has(node.key) : undefined;
     let setSize = 1;
-    if (node.level > 0 && node?.parentKey != null) {
+    if (node.level >= 0 && node?.parentKey != null) {
       let parent = state.collection.getItem(node.parentKey);
       if (parent) {
         // siblings must exist because our original node exists
-        let siblings = state.collection.getChildren?.(parent.key)!;
+        let siblings = getDirectChildren(parent as CollectionNode<T>, state.collection as Collection<CollectionNode<T>>);
         setSize = [...siblings].filter(row => row.type === 'item').length;
       }
     } else {
@@ -324,3 +325,13 @@ function last(walker: TreeWalker) {
   } while (last);
   return next;
 }
+
+function getDirectChildren<T>(parent: CollectionNode<T>, collection: Collection<CollectionNode<T>>) {
+  let node = parent?.firstChildKey != null ? collection.getItem(parent.firstChildKey) : null;
+  let siblings: CollectionNode<T>[] = [];
+  while (node) {
+    siblings.push(node);
+    node = node.nextKey != null ? collection.getItem(node.nextKey) : null;
+  }
+  return siblings;
+}

packages/@react-stately/data/src/useTreeData.ts

@@ -504,7 +504,7 @@ function moveItems<T extends object>(
     // decrement the index if the child being removed is in the target parent and before the target index
     // the root node is special, it is null, and will not have a key, however, a parentKey can still point to it
     if ((child.parentKey === toParent
-       || child.parentKey === toParent?.key)
+      || child.parentKey === toParent?.key)
       && keyArray.includes(child.key)
       && (toParent?.children ? toParent.children.indexOf(child) : items.indexOf(child)) < originalToIndex) {
       toIndex--;

packages/react-aria-components/src/GridList.tsx

@@ -646,7 +646,7 @@ export const GridListSection = /*#__PURE__*/ createBranchComponent(SectionNode,
 });
 
 export const GridListHeaderContext = createContext<ContextValue<HTMLAttributes<HTMLDivElement>, HTMLDivElement>>({});
-const GridListHeaderInnerContext = createContext<HTMLAttributes<HTMLElement> | null>(null);
+export const GridListHeaderInnerContext = createContext<HTMLAttributes<HTMLElement> | null>(null);
 
 export const GridListHeader = /*#__PURE__*/ createLeafComponent(HeaderNode, function Header(props: HTMLAttributes<HTMLElement>, ref: ForwardedRef<HTMLDivElement>) {
   [props, ref] = useContextProps(props, ref, GridListHeaderContext);