Email.php

<?php

namespace Drupal\Core\Render\Element;

use Drupal\Core\Form\FormStateInterface;
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 FormElement {
    
    /**
     * 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;
    }

}