Function move

packages/react-stately/src/data/useTreeData.ts:379–419

(key: Key, toParentKey: Key | null, index: number)

      this.remove(...selectedKeys);
    },
    move(key: Key, toParentKey: Key | null, index: number) {
      setItems(({items, nodeMap: originalMap}) => {
        let node = originalMap.get(key);
        if (!node) {
          return {items, nodeMap: originalMap};
        }

        let {items: newItems, nodeMap: newMap} = updateTree(items, key, () => null, originalMap);

        const movedNode = {
          ...node,
          parentKey: toParentKey
        };

        // If parentKey is null, insert into the root.
        if (toParentKey == null) {
          addNode(movedNode, newMap);
          return {
            items: [...newItems.slice(0, index), movedNode, ...newItems.slice(index)],
            nodeMap: newMap
          };
        }

        // Otherwise, update the parent node and its ancestors.
        return updateTree(
          newItems,
          toParentKey,
          parentNode => ({
            key: parentNode.key,
            parentKey: parentNode.parentKey,
            value: parentNode.value,
            children: [
              ...parentNode.children!.slice(0, index),
              movedNode,
              ...parentNode.children!.slice(index)
            ]
          }),
          newMap
        );
      });
    },
    moveBefore(key: Key, keys: Iterable<Key>) {
      setItems(prevState => {
        let {items, nodeMap} = prevState;