FormElementHelper.php

<?php

namespace Drupal\Core\Form;

use Drupal\Core\Render\Element;

/**
 * Provides common functionality for form elements.
 */
class FormElementHelper {
    
    /**
     * Retrieves a form element.
     *
     * @param string $name
     *   The name of the form element. If the #parents property of your form
     *   element is ['foo', 'bar', 'baz'] then the name is 'foo][bar][baz'.
     * @param array $form
     *   An associative array containing the structure of the form.
     *
     * @return array
     *   The form element.
     */
    public static function getElementByName($name, array $form) {
        foreach (Element::children($form) as $key) {
            if (implode('][', $form[$key]['#parents']) === $name) {
                return $form[$key];
            }
            elseif ($element = static::getElementByName($name, $form[$key])) {
                return $element;
            }
        }
        return [];
    }
    
    /**
     * Returns the title for the element.
     *
     * If the element has no title, this will recurse through all children of the
     * element until a title is found.
     *
     * @param array $element
     *   An associative array containing the properties of the form element.
     *
     * @return string
     *   The title of the element, or an empty string if none is found.
     */
    public static function getElementTitle(array $element) {
        $title = '';
        if (isset($element['#title'])) {
            $title = $element['#title'];
        }
        else {
            foreach (Element::children($element) as $key) {
                if ($title = static::getElementTitle($element[$key])) {
                    break;
                }
            }
        }
        return $title;
    }

}