GeneratingIterable<T> class

An Iterable whose first value is the result of initial and whose subsequent values are generated by passing the current value to the next function.

The class is useful for creating lazy iterables from object hierarchies and graphs.

The initial value and next function are required to generate a sequence that eventually terminates, otherwise calling methods that expect a finite sequence, like length or last, will cause an infinite loop.

Example:

class Node {
  Node parent;

  /// An iterable of node and all ancestors up to the root.
  Iterable<Node> ancestors =
      new GeneratingIterable<Node>(() => this, (n) => n.parent);

  /// An iterable of the root and the path of nodes to this. The
  /// reverse of ancestors.
  Iterable<Node> path = ancestors.toList().reversed();
}