Scoped Tree CakePHP Behavior

<?php
/**
 * Scoped Tree behavior - Created by Arno Esterhuizen from code by Jamie Nay to add better scope support.
 *
 * Scoped Tree behavior class.
 *
 * Enables a model object to act as a node-based tree, with subtrees allowed.
 */
App::import('Behavior', 'Tree');

class ScopedTreeBehavior extends TreeBehavior {
/**
 * Initiate Tree behavior
 *
 * @param object $Model instance of model
 * @param array $config array of configuration settings.
 * @return void
 * @access public
 */
    function setup(&$Model, $config = array()) {
        parent::setup($Model, $config = array());

        if (!is_array($config)) {
            $config = array('type' => $config);
        }
        $settings = array_merge($this->_defaults, $config);

        if (in_array($settings['scope'], $Model->getAssociated('belongsTo'))) {
            $data = $Model->getAssociated($settings['scope']);
            $this->settings[$Model->alias]['scopeForeignKey'] = $data['foreignKey'];
        }
    }
/**
 * Before save method. Called before all saves
 *
 * Overriden to transparently manage setting the lft and rght fields if and only if the parent field is included in the
 * parameters to be saved. For newly created nodes with NO parent the left and right field values are set directly by
 * this method bypassing the setParent logic.
 *
 * @since         1.2
 * @param AppModel $Model Model instance
 * @return boolean true to continue, false to abort the save
 * @access public
 */
    function beforeSave(&$Model) {
        // Correct the scope of the behavior settings if required.
        $this->_addScopeForeignKey($Model);

        parent::beforeSave($Model);
    }

/**
 * add a foreign ID scope to the model settings.
 *
 * @param AppModel $Model Model instance
 * @return true on success, false on failure
 * @access protected
 */
    function _addScopeForeignKey(&$Model) {
        if (!isset($this->settings[$Model->alias]['scopeForeignKey'])) {
            return false;
        }

        if (!isset($Model->data[$Model->alias][$this->settings[$Model->alias]['scopeForeignKey']])) {
            return false;
        }

        $this->settings[$Model->alias]['scope'] = array($Model->alias . '.' . $this->settings[$Model->alias]['scopeForeignKey'] => $Model->data[$Model->alias][$this->settings[$Model->alias]['scopeForeignKey']]);

        return true;
    }
}
?>