public function sortKey() {
    if ($this instanceof RootNode) {
      return spl_object_hash($this);
    }
    if (!$this->parent) {
      return '~/' . spl_object_hash($this);
    }
    $path = $this->parent->sortKey() . '/';
    $position = 0;
    $previous = $this->previous;
    while ($previous) {
      $position++;
      $previous = $previous->previous;
    }
    $path .= $position;
    return $path;
  }
public function sortKey() {
    if ($this instanceof RootNode) {
      return spl_object_hash($this);
    }
    if (!$this->parent) {
      return '~/' . spl_object_hash($this);
    }
    $path = $this->parent->sortKey() . '/';
    $position = 0;
    $previous = $this->previous;
    while ($previous) {
      $position++;
      $previous = $previous->previous;
    }
    $path .= $position;
    return $path;
  }
public function sortKey ( ) { if ( $ this instanceof RootNode ) { return spl_object_hash ( $ this ) ; } if ( ! $ this -> parent ) { return '~/' . spl_object_hash ( $ this ) ; } $ path = $ this -> parent -> sortKey ( ) . '/' ; $ position = 0 ; $ previous = $ this -> previous ; while ( $ previous ) { $ position ++ ; $ previous = $ previous -> previous ; } $ path .= $ position ; return $ path ; }
Get a unique key for sorting this node.

Used to sort nodes into tree order. That is top to bottom and then left
to right.

@return string
Get a unique key for sorting this node .