Function visitTree

src/common/map.ts:146–178

(
  node: Node<Path, Leaf>,
  path: Path[],
  ensureLeaf?: () => Leaf,
  pruneLeaf?: (leaf: Leaf) => 1 | 0 | void,
  p = 0,
)

export type Node<Path, Leaf> = Map<Path, Node<Path, Leaf> | Leaf>;
export const visitTree = <Path, Leaf>(
  node: Node<Path, Leaf>,
  path: Path[],
  ensureLeaf?: () => Leaf,
  pruneLeaf?: (leaf: Leaf) => 1 | 0 | void,
  p = 0,
): Leaf | undefined =>
  ifNotUndefined(
    (ensureLeaf ? mapEnsure : mapGet)(
      node,
      path[p],
      p > size(path) - 2 ? (ensureLeaf as () => Leaf) : mapNew,
    ),
    (nodeOrLeaf) => {
      if (p > size(path) - 2) {
        if (pruneLeaf?.(nodeOrLeaf as Leaf)) {
          mapSet(node, path[p]);
        }
        return nodeOrLeaf as Leaf;
      }
      const leaf = visitTree(
        nodeOrLeaf as Node<Path, Leaf>,
        path,
        ensureLeaf,
        pruneLeaf,
        p + 1,
      ) as Leaf;
      if (collIsEmpty(nodeOrLeaf as Node<Path, Leaf>)) {
        mapSet(node, path[p]);
      }
      return leaf;
    },
  );