Function computeNodeState

packages/core/src/widgets/tree.ts:123–143

(
  flatNode: FlattenedNode<T>,
  expanded: readonly string[],
  selected: string | undefined,
  focused: string | undefined,
  loading: ReadonlySet<string>,
  expandedSet?: ReadonlySet<string>,
)

 * @returns NodeState for the node
 */
export function computeNodeState<T>(
  flatNode: FlattenedNode<T>,
  expanded: readonly string[],
  selected: string | undefined,
  focused: string | undefined,
  loading: ReadonlySet<string>,
  expandedSet?: ReadonlySet<string>,
): NodeState {
  const expandedLookup = expandedSet ?? new Set(expanded);

  return Object.freeze({
    expanded: expandedLookup.has(flatNode.key),
    selected: flatNode.key === selected,
    focused: flatNode.key === focused,
    loading: loading.has(flatNode.key),
    depth: flatNode.depth,
    isFirst: flatNode.siblingIndex === 0,
    isLast: flatNode.siblingIndex === flatNode.siblingCount - 1,
    hasChildren: flatNode.hasChildren,
  });
}

/* ========== Tree Line Characters ========== */