/**
* {@inheritdoc}
*/
public function setParent(NodeInterface $parent = null)
{
if ($parent === $this) {
throw new \InvalidArgumentException('A node cannot have itself as a parent');
}
if ($parent === $this->parent) {
return $this;
}
if ($this->parent !== null) {
$this->parent->remove($this);
}
$this->parent = $parent;
if ($this->parent !== null && !$this->parent->contains($this, false)) {
$this->parent->add($this);
}
return $this;
}