/**
* Sets $element as $pos child, overwrites existent if any
*
* @param DataTreeBase $element
* @throws \InvalidArgumentException
*/
protected function setChild(DataTreeBase $element, $pos)
{
if (!is_int($pos) || $pos < 0) {
throw new \InvalidArgumentException('Pos have to be a positive integer');
} elseif ($this->getValue()) {
throw new \InvalidArgumentException('Cannot set a child if tree is a leaf one');
} else {
$element->setParent($this);
$this->elements[$pos] = $element;
}
}
