/// <summary>
/// Expert: this method is called by <see cref="IndexReader"/>s which wrap other readers
/// (e.g. <see cref="CompositeReader"/> or <see cref="FilterAtomicReader"/>) to register the parent
/// at the child (this reader) on construction of the parent. When this reader is disposed,
/// it will mark all registered parents as disposed, too. The references to parent readers
/// are weak only, so they can be GCed once they are no longer in use.
/// @lucene.experimental
/// </summary>
public void RegisterParentReader(IndexReader reader)
{
EnsureOpen();
parentReaders.Add(new IdentityWeakReference <IndexReader>(reader));
}
