Email.php

<?php

namespace Drupal\Core\Render\Element;

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\Attribute\FormElement;
use Drupal\Core\Render\Element;

/**
 * Provides a form input element for entering an email address.
 *
 * Properties:
 * - #default_value: An RFC-compliant email address.
 * - #size: The size of the input element in characters.
 * - #pattern: A string for the native HTML5 pattern attribute.
 *
 * Example usage:
 * @code
 * $form['email'] = [
 *   '#type' => 'email',
 *   '#title' => $this->t('Email'),
 *   '#pattern' => '*@example.com',
 * ];
 * @endcode
 *
 * @see \Drupal\Core\Render\Element\Textfield
 */

#[FormElement('email')]
class Email extends FormElementBase {

  /**
   * Defines the max length for an email address.
   *
   * The maximum length of an email address is 254 characters. RFC 3696
   * specifies a total length of 320 characters, but mentions that
   * addresses longer than 256 characters are not normally useful. Erratum
   * 1690 was then released which corrected this value to 254 characters.
   * @see http://tools.ietf.org/html/rfc3696#section-3
   * @see http://www.rfc-editor.org/errata_search.php?rfc=3696&eid=1690
   */
  const EMAIL_MAX_LENGTH = 254;

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    $class = static::class;
    return [
      '#input' => TRUE,
      '#size' => 60,
      '#maxlength' => self::EMAIL_MAX_LENGTH,
      '#autocomplete_route_name' => FALSE,
      '#process' => [
        [
          $class,
          'processAutocomplete',
        ],
        [
          $class,
          'processAjaxForm',
        ],
        [
          $class,
          'processPattern',
        ],
      ],
      '#element_validate' => [
        [
          $class,
          'validateEmail',
        ],
      ],
      '#pre_render' => [
        [
          $class,
          'preRenderEmail',
        ],
      ],
      '#theme' => 'input__email',
      '#theme_wrappers' => [
        'form_element',
      ],
    ];
  }

  /**
   * Form element validation handler for #type 'email'.
   *
   * Note that #maxlength and #required is validated by _form_validate() already.
   */
  public static function validateEmail(&$element, FormStateInterface $form_state, &$complete_form) {
    $value = trim($element['#value']);
    $form_state
      ->setValueForElement($element, $value);
    if ($value !== '' && !\Drupal::service('email.validator')
      ->isValid($value)) {
      $form_state
        ->setError($element, t('The email address %mail is not valid. Use the format user@example.com.', [
        '%mail' => $value,
      ]));
    }
  }

  /**
   * Prepares a #type 'email' render element for input.html.twig.
   *
   * @param array $element
   *   An associative array containing the properties of the element.
   *   Properties used: #title, #value, #description, #size, #maxlength,
   *   #placeholder, #required, #attributes.
   *
   * @return array
   *   The $element with prepared variables ready for input.html.twig.
   */
  public static function preRenderEmail($element) {
    $element['#attributes']['type'] = 'email';
    Element::setAttributes($element, [
      'id',
      'name',
      'value',
      'size',
      'maxlength',
      'placeholder',
    ]);
    static::setAttributes($element, [
      'form-email',
    ]);
    return $element;
  }

}