eachBefore method

T eachBefore(TreeFun<T> callback)

先序遍历

Implementation

T eachBefore(TreeFun<T> callback) {
  List<T> nodes = [this as T];
  List<T> children;
  int index = -1;
  while (nodes.isNotEmpty) {
    T node = nodes.removeLast();
    if (callback.call(node, ++index, this as T)) {
      break;
    }
    children = node._childrenList;
    if (children.isNotEmpty) {
      for (int i = children.length - 1; i >= 0; --i) {
        nodes.add(children[i]);
      }
    }
  }
  return this as T;
}