Add the iteratition feature of the TYPO3 Fluid ForViewHelper to the GroupedForViewhelper

GroupedForViewHelper.php

<?php
namespace Pixelbrackets\AcmeSitepackage\ViewHelpers;

use TYPO3\CMS\Fluid\Core\ViewHelper\AbstractViewHelper;

/**
 * Grouped loop viewhelper
 *
 * Iterates through elements and groups them by a specified property first
 *
 * This custom viewhelper adds the iteratition feature of the ForViewHelper to the GroupedForViewhelper
 *
 * @see TYPO3\CMS\Fluid\ViewHelpers\GroupedForViewHelper & TYPO3\CMS\Fluid\ViewHelpers\ForViewHelper
 */

class GroupedForViewHelper extends AbstractViewHelper {

	/**
	 * Iterates through elements of $each and renders child nodes
	 *
	 * @param array $each The array or \TYPO3\CMS\Extbase\Persistence\ObjectStorage to iterated over
	 * @param string $as The name of the iteration variable
	 * @param string $groupBy Group by this property
	 * @param string $groupKey The name of the variable to store the current group
	 * @param string $iteration The name of the variable to store iteration information (index, cycle, isFirst, isLast, isEven, isOdd)
	 * @return string Rendered string
	 * @throws \TYPO3\CMS\Fluid\Core\ViewHelper\Exception
	 * @api
	 */
	public function render($each, $as, $groupBy, $groupKey = 'groupKey', $iteration = NULL) {
		$output = '';
		if ($each === NULL) {
			return '';
		}
		if (is_object($each)) {
			if (!$each instanceof \Traversable) {
				throw new \TYPO3\CMS\Fluid\Core\ViewHelper\Exception('GroupedForViewHelper only supports arrays and objects implementing \Traversable interface', 1253108907);
			}
			$each = iterator_to_array($each);
		}

		$groups = $this->groupElements($each, $groupBy);

		if ($iteration !== NULL) {
			$iterationData = array(
				'index' => 0,
				'cycle' => 1,
				'total' => count($groups)
			);
		}

		foreach ($groups['values'] as $currentGroupIndex => $group) {
			$this->templateVariableContainer->add($groupKey, $groups['keys'][$currentGroupIndex]);
			$this->templateVariableContainer->add($as, $group);

			if (iteration !== NULL) {
				$iterationData['isFirst'] = $iterationData['cycle'] === 1;
				$iterationData['isLast'] = $iterationData['cycle'] === $iterationData['total'];
				$iterationData['isEven'] = $iterationData['cycle'] % 2 === 0;
				$iterationData['isOdd'] = !$iterationData['isEven'];
				$this->templateVariableContainer->add($iteration, $iterationData);
				$iterationData['index']++;
				$iterationData['cycle']++;
			}

			$output .= $this->renderChildren();
			$this->templateVariableContainer->remove($groupKey);
			$this->templateVariableContainer->remove($as);
			if (iteration !== NULL) {
				$this->templateVariableContainer->remove($iteration);
			}
		}
		return $output;
	}

	/**
	 * Groups the given array by the specified groupBy property.
	 *
	 * @param array $elements The array / traversable object to be grouped
	 * @param string $groupBy Group by this property
	 * @return array The grouped array in the form array('keys' => array('key1' => [key1value], 'key2' => [key2value], ...), 'values' => array('key1' => array([key1value] => [element1]), ...), ...)
	 * @throws \TYPO3\CMS\Fluid\Core\ViewHelper\Exception
	 */
	protected function groupElements(array $elements, $groupBy) {
		$groups = array('keys' => array(), 'values' => array());
		foreach ($elements as $key => $value) {
			if (is_array($value)) {
				$currentGroupIndex = isset($value[$groupBy]) ? $value[$groupBy] : NULL;
			} elseif (is_object($value)) {
				$currentGroupIndex = \TYPO3\CMS\Extbase\Reflection\ObjectAccess::getPropertyPath($value, $groupBy);
			} else {
				throw new \TYPO3\CMS\Fluid\Core\ViewHelper\Exception('GroupedForViewHelper only supports multi-dimensional arrays and objects', 1253120365);
			}
			$currentGroupKeyValue = $currentGroupIndex;
			if (is_object($currentGroupIndex)) {
				if ($currentGroupIndex instanceof \TYPO3\CMS\Extbase\Persistence\Generic\LazyLoadingProxy) {
					$currentGroupIndex = $currentGroupIndex->_loadRealInstance();
				}
				$currentGroupIndex = spl_object_hash($currentGroupIndex);
			}
			$groups['keys'][$currentGroupIndex] = $currentGroupKeyValue;
			$groups['values'][$currentGroupIndex][$key] = $value;
		}
		return $groups;
	}
}

?>