FlowQueryOperation "slide" for TYPO3 Neos to get the property of parent Nodes

Root.ts

backgroundImage = ${q(node).slide('backgroundImage').property('backgroundImage')}

SlideOperation.php

<?php
namespace Your\Package\TypoScript\FlowQueryOperations;

/*                                                                        *
 * This script belongs to the TYPO3 Flow package "TYPO3.Neos".            *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU General Public License, either version 3 of the   *
 * License, or (at your option) any later version.                        *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */

use TYPO3\Eel\FlowQuery\FlowQuery;
use TYPO3\Eel\FlowQuery\Operations\AbstractOperation;
use TYPO3\Flow\Annotations as Flow;
use TYPO3\TYPO3CR\Domain\Model\NodeInterface;

/**
 * "slide" operation working on TYPO3CR nodes. It iterates over all
 * context elements and returns the node which matches the property
 * specified as optional argument.
 */
class SlideOperation extends AbstractOperation {

	/**
	 * {@inheritdoc}
	 *
	 * @var string
	 */
	static protected $shortName = 'slide';

	/**
	 * {@inheritdoc}
	 *
	 * @var integer
	 */
	static protected $priority = 100;

	/**
	 * {@inheritdoc}
	 *
	 * @param array (or array-like object) $context onto which this operation should be applied
	 * @return boolean TRUE if the operation can be applied onto the $context, FALSE otherwise
	 */
	public function canEvaluate($context) {
		return count($context) === 0 || (isset($context[0]) && ($context[0] instanceof NodeInterface));
	}

	/**
	 * {@inheritdoc}
	 *
	 * @param FlowQuery $flowQuery the FlowQuery object
	 * @param array $arguments the arguments for this operation
	 * @return void
	 */
	public function evaluate(FlowQuery $flowQuery, array $arguments) {
		$output = array();
		foreach ($flowQuery->getContext() as $contextNode) {
			while ($contextNode->getParent() !== NULL) {
				$res = $contextNode->getProperty($arguments[0]);
				if (!empty($res)) {
					$output[] = $contextNode;
					break;
				}
				$contextNode = $contextNode->getParent();
			}
		}

		$flowQuery->setContext($output);
	}
}