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<?php

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/**
 * @file
 * Common functions that many Drupal modules will need to reference.
 *
 * The functions that are critical and need to be available even when serving
 * a cached page are instead located in bootstrap.inc.
 */

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use Drupal\Component\Serialization\Json;
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use Drupal\Component\Serialization\Yaml;
use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
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use Drupal\Component\Utility\Bytes;
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use Drupal\Component\Utility\Crypt;
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use Drupal\Component\Utility\Html;
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use Drupal\Component\Utility\Number;
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use Drupal\Component\Utility\SafeMarkup;
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use Drupal\Component\Utility\SortArray;
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use Drupal\Component\Utility\String;
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use Drupal\Component\Utility\Tags;
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use Drupal\Component\Utility\UrlHelper;
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use Drupal\Core\Cache\Cache;
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use Drupal\Core\Language\LanguageInterface;
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use Drupal\Core\Site\Settings;
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use Drupal\Core\Url;
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use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Request;
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use Drupal\Core\PhpStorage\PhpStorageFactory;
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use Drupal\Component\Utility\NestedArray;
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use Drupal\Core\Datetime\DrupalDateTime;
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use Drupal\Core\Routing\GeneratorNotInitializedException;
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use Drupal\Core\Template\Attribute;
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use Drupal\Core\Render\Element;
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use Drupal\Core\Session\AnonymousUserSession;
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/**
 * @defgroup php_wrappers PHP wrapper functions
 * @{
 * Functions that are wrappers or custom implementations of PHP functions.
 *
 * Certain PHP functions should not be used in Drupal. Instead, Drupal's
 * replacement functions should be used.
 *
 * For example, for improved or more secure UTF8-handling, or RFC-compliant
 * handling of URLs in Drupal.
 *
 * For ease of use and memorizing, all these wrapper functions use the same name
 * as the original PHP function, but prefixed with "drupal_". Beware, however,
 * that not all wrapper functions support the same arguments as the original
 * functions.
 *
 * You should always use these wrapper functions in your code.
 *
 * Wrong:
 * @code
 *   $my_substring = substr($original_string, 0, 5);
 * @endcode
 *
 * Correct:
 * @code
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 *   $my_substring = Unicode::substr($original_string, 0, 5);
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 * @endcode
 *
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 * @}
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 */

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/**
 * Return status for saving which involved creating a new item.
 */
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const SAVED_NEW = 1;
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/**
 * Return status for saving which involved an update to an existing item.
 */
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const SAVED_UPDATED = 2;
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/**
 * Return status for saving which deleted an existing item.
 */
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const SAVED_DELETED = 3;
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/**
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 * The default aggregation group for CSS files added to the page.
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 */
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const CSS_AGGREGATE_DEFAULT = 0;
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/**
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 * The default aggregation group for theme CSS files added to the page.
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 */
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const CSS_AGGREGATE_THEME = 100;

/**
 * The default weight for CSS rules that style HTML elements ("base" styles).
 */
const CSS_BASE = -200;

/**
 * The default weight for CSS rules that layout a page.
 */
const CSS_LAYOUT = -100;

/**
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 * The default weight for CSS rules that style design components (and their associated states and themes.)
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 */
const CSS_COMPONENT = 0;

/**
 * The default weight for CSS rules that style states and are not included with components.
 */
const CSS_STATE = 100;

/**
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 * The default weight for CSS rules that style themes and are not included with components.
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 */
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const CSS_THEME = 200;
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/**
 * The default group for JavaScript settings added to the page.
 */
const JS_SETTING = -200;

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/**
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 * The default group for JavaScript and jQuery libraries added to the page.
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 */
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const JS_LIBRARY = -100;
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/**
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 * The default group for module JavaScript code added to the page.
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 */
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const JS_DEFAULT = 0;
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/**
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 * The default group for theme JavaScript code added to the page.
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 */
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const JS_THEME = 100;
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/**
 * The delimiter used to split plural strings.
 *
 * This is the ETX (End of text) character and is used as a minimal means to
 * separate singular and plural variants in source and translation text. It
 * was found to be the most compatible delimiter for the supported databases.
 */
const LOCALE_PLURAL_DELIMITER = "\03";

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/**
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 * Adds output to the HEAD tag of the HTML page.
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 *
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 * This function can be called as long as the headers aren't sent. Pass no
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 * arguments (or NULL for both) to retrieve the currently stored elements.
 *
 * @param $data
 *   A renderable array. If the '#type' key is not set then 'html_tag' will be
 *   added as the default '#type'.
 * @param $key
 *   A unique string key to allow implementations of hook_html_head_alter() to
 *   identify the element in $data. Required if $data is not NULL.
 *
 * @return
 *   An array of all stored HEAD elements.
 *
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 * @see \Drupal\Core\Render\Element\HtmlTag::preRenderHtmlTag()
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 *
 * @deprecated in Drupal 8.0.x, will be removed before Drupal 8.0.0
 *   Use #attached on render arrays.
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 */
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function _drupal_add_html_head($data = NULL, $key = NULL) {
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  $stored_head = &drupal_static(__FUNCTION__, array());
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  if (isset($data) && isset($key)) {
    if (!isset($data['#type'])) {
      $data['#type'] = 'html_tag';
    }
    $stored_head[$key] = $data;
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  }
  return $stored_head;
}

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/**
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 * Retrieves output to be displayed in the HEAD tag of the HTML page.
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 *
 * @param bool $render
 *   If TRUE render the HEAD elements, otherwise return just the elements.
 *
 * @return string|array
 *   Return the rendered HTML head or the elements itself.
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 *
 * @deprecated in Drupal 8.0.x, will be removed before Drupal 8.0.0
 *   Use #attached on render arrays.
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 */
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function drupal_get_html_head($render = TRUE) {
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  $elements = _drupal_add_html_head();
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  \Drupal::moduleHandler()->alter('html_head', $elements);
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  if ($render) {
    return drupal_render($elements);
  }
  else {
    return $elements;
  }
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}

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/**
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 * Prepares a 'destination' URL query parameter for use with url().
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 *
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 * Used to direct the user back to the referring page after completing a form.
 * By default the current URL is returned. If a destination exists in the
 * previous request, that destination is returned. As such, a destination can
 * persist across multiple pages.
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 *
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 * @return
 *   An associative array containing the key:
 *   - destination: The path provided via the destination query string or, if
 *     not available, the current path.
 *
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 * @ingroup form_api
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 */
function drupal_get_destination() {
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  $destination = &drupal_static(__FUNCTION__);

  if (isset($destination)) {
    return $destination;
  }

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  $query = \Drupal::request()->query;
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  if ($query->has('destination')) {
    $destination = array('destination' => $query->get('destination'));
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  }
  else {
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    $path = \Drupal::routeMatch()->getRouteName() ? Url::fromRouteMatch(\Drupal::routeMatch())->getInternalPath() : '';
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    $query = UrlHelper::buildQuery(UrlHelper::filterQueryParameters($query->all()));
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    if ($query != '') {
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      $path .= '?' . $query;
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    }
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    $destination = array('destination' => $path);
  }
  return $destination;
}

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/**
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 * @defgroup validation Input validation
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 * @{
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 * Functions to validate user input.
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 */

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/**
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 * Verifies the syntax of the given email address.
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 *
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 * This uses the
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 * @link http://php.net/manual/filter.filters.validate.php PHP email validation filter. @endlink
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 *
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 * @param $mail
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 *   A string containing an email address.
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 *
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 * @return
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 *   TRUE if the address is in a valid format.
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 */
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function valid_email_address($mail) {
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  return (bool)filter_var($mail, FILTER_VALIDATE_EMAIL);
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}

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/**
 * @} End of "defgroup validation".
 */

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/**
 * @defgroup sanitization Sanitization functions
 * @{
 * Functions to sanitize values.
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 *
 * See http://drupal.org/writing-secure-code for information
 * on writing secure code.
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 */

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/**
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 * Strips dangerous protocols from a URI and encodes it for output to HTML.
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 *
 * @param $uri
 *   A plain-text URI that might contain dangerous protocols.
 *
 * @return
 *   A URI stripped of dangerous protocols and encoded for output to an HTML
 *   attribute value. Because it is already encoded, it should not be set as a
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 *   value within a $attributes array passed to Drupal\Core\Template\Attribute,
 *   because Drupal\Core\Template\Attribute expects those values to be
 *   plain-text strings. To pass a filtered URI to
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 *   Drupal\Core\Template\Attribute, call
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 *   \Drupal\Component\Utility\UrlHelper::stripDangerousProtocols() instead.
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 *
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 * @see \Drupal\Component\Utility\UrlHelper::stripDangerousProtocols()
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 * @see \Drupal\Component\Utility\String::checkPlain()
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 */
function check_url($uri) {
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  return String::checkPlain(UrlHelper::stripDangerousProtocols($uri));
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}

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/**
 * @} End of "defgroup sanitization".
 */

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/**
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 * @defgroup format Formatting
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 * @{
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 * Functions to format numbers, strings, dates, etc.
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 */

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/**
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 * Formats XML elements.
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 *
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 * Note: It is the caller's responsibility to sanitize any input parameters.
 * This function does not perform sanitization.
 *
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 * @param $array
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 *   An array where each item represents an element and is either a:
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 *   - (key => value) pair (<key>value</key>)
 *   - Associative array with fields:
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 *     - 'key': The element name. Element names are not sanitized, so do not
 *       pass user input.
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 *     - 'value': element contents
 *     - 'attributes': associative array of element attributes
 *
 * In both cases, 'value' can be a simple string, or it can be another array
 * with the same format as $array itself for nesting.
 */
function format_xml_elements($array) {
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  $output = '';
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  foreach ($array as $key => $value) {
    if (is_numeric($key)) {
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      if ($value['key']) {
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        $output .= ' <' . $value['key'];
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        if (isset($value['attributes']) && is_array($value['attributes'])) {
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          $output .= new Attribute($value['attributes']);
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        }

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        if (isset($value['value']) && $value['value'] != '') {
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          $output .= '>' . (is_array($value['value']) ? format_xml_elements($value['value']) : String::checkPlain($value['value'])) . '</' . $value['key'] . ">\n";
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        }
        else {
          $output .= " />\n";
        }
      }
    }
    else {
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      $output .= ' <' . $key . '>' . (is_array($value) ? format_xml_elements($value) : String::checkPlain($value)) . "</$key>\n";
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    }
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  }
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  // @todo This is marking the output string as safe HTML, but we have only
  //   sanitized the attributes and tag values, not the tag names, and we
  //   cannot guarantee the assembled markup is safe. Consider a fix in:
  //   https://www.drupal.org/node/2296885
  return SafeMarkup::set($output);
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}

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/**
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 * Generates a string representation for the given byte count.
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 *
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 * @param $size
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 *   A size in bytes.
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 * @param $langcode
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 *   Optional language code to translate to a language other than what is used
 *   to display the page.
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 *
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 * @return
 *   A translated string representation of the size.
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 */
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function format_size($size, $langcode = NULL) {
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  if ($size < Bytes::KILOBYTE) {
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    return \Drupal::translation()->formatPlural($size, '1 byte', '@count bytes', array(), array('langcode' => $langcode));
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  }
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  else {
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    $size = $size / Bytes::KILOBYTE; // Convert bytes to kilobytes.
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    $units = array(
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      t('@size KB', array(), array('langcode' => $langcode)),
      t('@size MB', array(), array('langcode' => $langcode)),
      t('@size GB', array(), array('langcode' => $langcode)),
      t('@size TB', array(), array('langcode' => $langcode)),
      t('@size PB', array(), array('langcode' => $langcode)),
      t('@size EB', array(), array('langcode' => $langcode)),
      t('@size ZB', array(), array('langcode' => $langcode)),
      t('@size YB', array(), array('langcode' => $langcode)),
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    );
    foreach ($units as $unit) {
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      if (round($size, 2) >= Bytes::KILOBYTE) {
        $size = $size / Bytes::KILOBYTE;
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      }
      else {
        break;
      }
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    }
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    return str_replace('@size', round($size, 2), $unit);
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  }
}

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/**
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 * Formats a date, using a date type or a custom date format string.
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 *
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 * @param $timestamp
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 *   A UNIX timestamp to format.
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 * @param $type
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 *   (optional) The format to use, one of:
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 *   - One of the built-in formats: 'short', 'medium',
 *     'long', 'html_datetime', 'html_date', 'html_time',
 *     'html_yearless_date', 'html_week', 'html_month', 'html_year'.
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 *   - The name of a date type defined by a date format config entity.
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 *   - The machine name of an administrator-defined date format.
 *   - 'custom', to use $format.
 *   Defaults to 'medium'.
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 * @param $format
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 *   (optional) If $type is 'custom', a PHP date format string suitable for
 *   input to date(). Use a backslash to escape ordinary text, so it does not
 *   get interpreted as date format characters.
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 * @param $timezone
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 *   (optional) Time zone identifier, as described at
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 *   http://php.net/manual/timezones.php Defaults to the time zone used to
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 *   display the page.
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 * @param $langcode
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 *   (optional) Language code to translate to. Defaults to the language used to
 *   display the page.
 *
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 * @return
 *   A translated date string in the requested format.
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 *
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 * @see \Drupal\Core\Datetime\DateFormatter::format()
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 */
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function format_date($timestamp, $type = 'medium', $format = '', $timezone = NULL, $langcode = NULL) {
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  return \Drupal::service('date.formatter')->format($timestamp, $type, $format, $timezone, $langcode);
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}

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/**
 * Returns an ISO8601 formatted date based on the given date.
 *
 * @param $date
 *   A UNIX timestamp.
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 *
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 * @return string
 *   An ISO8601 formatted date.
 */
function date_iso8601($date) {
  // The DATE_ISO8601 constant cannot be used here because it does not match
  // date('c') and produces invalid RDF markup.
  return date('c', $date);
}

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/**
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 * Translates a formatted date string.
 *
 * Callback for preg_replace_callback() within format_date().
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 */
function _format_date_callback(array $matches = NULL, $new_langcode = NULL) {
  // We cache translations to avoid redundant and rather costly calls to t().
  static $cache, $langcode;

  if (!isset($matches)) {
    $langcode = $new_langcode;
    return;
  }

  $code = $matches[1];
  $string = $matches[2];

  if (!isset($cache[$langcode][$code][$string])) {
    $options = array(
      'langcode' => $langcode,
    );

    if ($code == 'F') {
      $options['context'] = 'Long month name';
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    }
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    if ($code == '') {
      $cache[$langcode][$code][$string] = $string;
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    }
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    else {
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      $cache[$langcode][$code][$string] = t($string, array(), $options);
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    }
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  }
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  return $cache[$langcode][$code][$string];
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}

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/**
 * @} End of "defgroup format".
 */
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/**
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 * Generates an internal or external URL.
 *
 * When creating links in modules, consider whether l() could be a better
 * alternative than url().
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 *
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 * @see \Drupal\Core\Url::fromUri()
 * @see \Drupal\Core\Url::fromRoute()
 * @see \Drupal\Core\Url::toString()
 *
 * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0.0.
 *   Use \Drupal\Core\Url::fromRoute() for internal paths served by Drupal
 *   controllers or \Drupal\Core\Url::fromUri() for external paths or
 *   non-controller or sub-domain URIs such as core/install.php. Note that
 *   \Drupal\Core\Url::fromUri() expects a valid URI including the scheme. URIs
 *   from the same sub-domain that are not handled by Drupal controllers should
 *   be prepended with base://. For example:
 * @code
 * $installer_url = \Drupal\Core\Url::fromUri('base://core/install.php')->toString();
 * $external_url = \Drupal\Core\Url::fromUri('http://example.com', ['query' => ['foo' => 'bar']])->toString();
 * $internal_url = \Drupal\Core\Url::fromRoute('system.admin')->toString();
 * @endcode
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 */
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function _url($path = NULL, array $options = array()) {
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  return \Drupal::urlGenerator()->generateFromPath($path, $options);
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}

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/**
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 * Formats an attribute string for an HTTP header.
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 *
 * @param $attributes
 *   An associative array of attributes such as 'rel'.
 *
 * @return
 *   A ; separated string ready for insertion in a HTTP header. No escaping is
 *   performed for HTML entities, so this string is not safe to be printed.
 */
function drupal_http_header_attributes(array $attributes = array()) {
  foreach ($attributes as $attribute => &$data) {
    if (is_array($data)) {
      $data = implode(' ', $data);
    }
    $data = $attribute . '="' . $data . '"';
  }
  return $attributes ? ' ' . implode('; ', $attributes) : '';
}

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/**
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 * Formats an internal or external URL link as an HTML anchor tag.
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 *
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 * This function correctly handles aliased paths and adds an 'active' class
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 * attribute to links that point to the current page (for theming), so all
 * internal links output by modules should be generated by this function if
 * possible.
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 *
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 * However, for links enclosed in translatable text you should use t() and
 * embed the HTML anchor tag directly in the translated string. For example:
 * @code
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 * t('Visit the <a href="@url">settings</a> page', array('@url' => \Drupal::url('system.admin')));
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 * @endcode
 * This keeps the context of the link title ('settings' in the example) for
 * translators.
 *
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 * This function does not support generating links from internal routes. For
 * that use \Drupal\Core\Utility\LinkGenerator::generate(), which is exposed via
 * the 'link_generator' service. It requires an internal route name and does not
 * support external URLs. Using Drupal 7 style system paths should be avoided if
 * possible but l() should still be used when rendering links to external URLs.
 *
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 * @param string|array $text
 *   The link text for the anchor tag as a translated string or render array.
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 * @param string $path
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 *   The internal path or external URL being linked to, such as "node/34" or
 *   "http://example.com/foo". After the url() function is called to construct
 *   the URL from $path and $options, the resulting URL is passed through
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 *   \Drupal\Component\Utility\String::checkPlain() before it is inserted into
 *   the HTML anchor tag, to ensure well-formed HTML. See url() for more
 *   information and notes.
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 * @param array $options
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 *   An associative array of additional options. Defaults to an empty array. It
 *   may contain the following elements.
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 *   - 'attributes': An associative array of HTML attributes to apply to the
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 *     anchor tag. If element 'class' is included, it must be an array; 'title'
 *     must be a string; other elements are more flexible, as they just need
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 *     to work as an argument for the constructor of the class
 *     Drupal\Core\Template\Attribute($options['attributes']).
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 *   - 'html' (default FALSE): Whether $text is HTML or just plain-text. For
 *     example, to make an image tag into a link, this must be set to TRUE, or
 *     you will see the escaped HTML image tag. $text is not sanitized if
 *     'html' is TRUE. The calling function must ensure that $text is already
 *     safe.
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 *   - 'language': An optional language object. If the path being linked to is
 *     internal to the site, $options['language'] is used to determine whether
 *     the link is "active", or pointing to the current page (the language as
 *     well as the path must match). This element is also used by url().
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 *   - 'set_active_class': Whether l() should compare the $path, language and
 *     query options to the current URL to determine whether the link is
 *     "active". Defaults to FALSE. If TRUE, an "active" class will be applied
 *     to the link. It is important to use this sparingly since it is usually
 *     unnecessary and requires extra processing.
 *     For anonymous users, the "active" class will be calculated on the server,
 *     because most sites serve each anonymous user the same cached page anyway.
 *     For authenticated users, the "active" class will be calculated on the
 *     client (through JavaScript), only data- attributes are added to links to
 *     prevent breaking the render cache. The JavaScript is added in
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 *     system_page_attachments().
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 *   - Additional $options elements used by the url() function.
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 *
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 * @return string
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 *   An HTML string containing a link to the given path.
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 *
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 * @see _url()
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 * @see system_page_attachments()
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 * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0.0.
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 *   Use \Drupal::l($text, $url) where $url is an instance of
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 *   \Drupal\Core\Url. To build a \Drupal\Core\Url object for internal paths
 *   served by Drupal controllers use \Drupal\Core\Url::fromRoute(). For
 *   external paths or non-controller or sub-domain URIs such as
 *   core/install.php use \Drupal\Core\Url::fromUri(). Note that
 *   \Drupal\Core\Url::fromUri() expects a valid URI including the scheme. URIs
 *   from the same sub-domain that are not handled by Drupal controllers should
 *   be prepended with base://. For example:
 * @code
 * $installer_url = \Drupal\Core\Url::fromUri('base://core/install.php')->toString();
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 * $installer_link = \Drupal::l($text, $installer_url);
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 * $external_url = \Drupal\Core\Url::fromUri('http://example.com', ['query' => ['foo' => 'bar']])->toString();
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 * $external_link = \Drupal::l($text, $external_url);
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 * $internal_url = \Drupal\Core\Url::fromRoute('system.admin')->toString();
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 * $internal_link = \Drupal::l($text, $internal_url);
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 * @endcode
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 */
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function _l($text, $path, array $options = array()) {
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  // Start building a structured representation of our link to be altered later.
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  $variables = array(
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    'text' => is_array($text) ? drupal_render($text) : $text,
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    'path' => $path,
    'options' => $options,
  );
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  // Merge in default options.
  $variables['options'] += array(
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    'attributes' => array(),
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    'query' => array(),
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    'html' => FALSE,
628
    'language' => NULL,
629
    'set_active_class' => FALSE,
630
  );
631

632 633 634
  // Add a hreflang attribute if we know the language of this link's url and
  // hreflang has not already been set.
  if (!empty($variables['options']['language']) && !isset($variables['options']['attributes']['hreflang'])) {
635
    $variables['options']['attributes']['hreflang'] = $variables['options']['language']->getId();
636 637
  }

638 639 640 641 642 643 644 645 646
  // Set the "active" class if the 'set_active_class' option is not empty.
  if (!empty($variables['options']['set_active_class'])) {
    // Add a "data-drupal-link-query" attribute to let the drupal.active-link
    // library know the query in a standardized manner.
    if (!empty($variables['options']['query'])) {
      $query = $variables['options']['query'];
      ksort($query);
      $variables['options']['attributes']['data-drupal-link-query'] = Json::encode($query);
    }
647

648 649 650
    // Add a "data-drupal-link-system-path" attribute to let the
    // drupal.active-link library know the path in a standardized manner.
    if (!isset($variables['options']['attributes']['data-drupal-link-system-path'])) {
651
      $variables['options']['attributes']['data-drupal-link-system-path'] = \Drupal::service('path.alias_manager')->getPathByAlias($path);
652
    }
653 654 655 656 657 658
  }

  // Remove all HTML and PHP tags from a tooltip, calling expensive strip_tags()
  // only when a quick strpos() gives suspicion tags are present.
  if (isset($variables['options']['attributes']['title']) && strpos($variables['options']['attributes']['title'], '<') !== FALSE) {
    $variables['options']['attributes']['title'] = strip_tags($variables['options']['attributes']['title']);
659
  }
660 661

  // Allow other modules to modify the structure of the link.
662
  \Drupal::moduleHandler()->alter('link', $variables);
663 664 665 666 667

  // Move attributes out of options. url() doesn't need them.
  $attributes = new Attribute($variables['options']['attributes']);
  unset($variables['options']['attributes']);

668 669
  // The result of url() is a plain-text URL. Because we are using it here
  // in an HTML argument context, we need to encode it properly.
670
  $url = String::checkPlain(_url($variables['path'], $variables['options']));
671

672 673
  // Sanitize the link text if necessary.
  $text = $variables['options']['html'] ? $variables['text'] : String::checkPlain($variables['text']);
674
  return SafeMarkup::set('<a href="' . $url . '"' . $attributes . '>' . $text . '</a>');
675 676
}

677 678 679 680 681 682 683 684
/**
 * Attempts to set the PHP maximum execution time.
 *
 * This function is a wrapper around the PHP function set_time_limit().
 * When called, set_time_limit() restarts the timeout counter from zero.
 * In other words, if the timeout is the default 30 seconds, and 25 seconds
 * into script execution a call such as set_time_limit(20) is made, the
 * script will run for a total of 45 seconds before timing out.
685
 *
686 687 688 689 690
 * If the current time limit is not unlimited it is possible to decrease the
 * total time limit if the sum of the new time limit and the current time spent
 * running the script is inferior to the original time limit. It is inherent to
 * the way set_time_limit() works, it should rather be called with an
 * appropriate value every time you need to allocate a certain amount of time
691
 * to execute a task than only once at the beginning of the script.
692
 *
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 * Before calling set_time_limit(), we check if this function is available
 * because it could be disabled by the server administrator. We also hide all
 * the errors that could occur when calling set_time_limit(), because it is
 * not possible to reliably ensure that PHP or a security extension will
 * not issue a warning/error if they prevent the use of this function.
 *
 * @param $time_limit
 *   An integer specifying the new time limit, in seconds. A value of 0
 *   indicates unlimited execution time.
702 703
 *
 * @ingroup php_wrappers
704 705 706
 */
function drupal_set_time_limit($time_limit) {
  if (function_exists('set_time_limit')) {
707 708
    $current = ini_get('max_execution_time');
    // Do not set time limit if it is currently unlimited.
709
    if ($current != 0) {
710 711
      @set_time_limit($time_limit);
    }
712 713 714
  }
}

715
/**
716
 * Returns the base URL path (i.e., directory) of the Drupal installation.
717
 *
718 719
 * base_path() adds a "/" to the beginning and end of the returned path if the
 * path is not empty. At the very least, this will return "/".
720
 *
721 722 723
 * Examples:
 * - http://example.com returns "/" because the path is empty.
 * - http://example.com/drupal/folder returns "/drupal/folder/".
724 725
 */
function base_path() {
726
  return $GLOBALS['base_path'];
727 728
}

729
/**
730
 * Adds a LINK tag with a distinct 'rel' attribute to the page's HEAD.
731
 *
732
 * This function can be called as long the HTML header hasn't been sent, which
733
 * on normal pages is up through the preprocess step of _theme('html'). Adding
734 735
 * a link will overwrite a prior link with the exact same 'rel' and 'href'
 * attributes.
736
 *
737 738 739 740
 * @param $attributes
 *   Associative array of element attributes including 'href' and 'rel'.
 * @param $header
 *   Optional flag to determine if a HTTP 'Link:' header should be sent.
741 742 743
 *
 * @deprecated in Drupal 8.0.x, will be removed before Drupal 8.0.0
 *   Use #attached on render arrays.
744
 */
745
function _drupal_add_html_head_link($attributes, $header = FALSE) {
746 747 748 749 750 751 752 753
  $element = array(
    '#tag' => 'link',
    '#attributes' => $attributes,
  );
  $href = $attributes['href'];

  if ($header) {
    // Also add a HTTP header "Link:".
754
    $href = '<' . String::checkPlain($attributes['href']) . '>;';
755
    unset($attributes['href']);
756
    $element['#attached']['http_header'][] = array('Link',  $href . drupal_http_header_attributes($attributes), TRUE);
757 758
  }

759
  _drupal_add_html_head($element, 'html_head_link:' . $attributes['rel'] . ':' . $href);
760 761
}

762
/**
763
 * Deletes old cached CSS files.
764
 *
765 766
 * @deprecated in Drupal 8.x, will be removed before Drupal 9.0.
 *   Use \Drupal\Core\Asset\AssetCollectionOptimizerInterface::deleteAll().
767
 */
768 769
function drupal_clear_css_cache() {
  \Drupal::service('asset.css.collection_optimizer')->deleteAll();
770 771
}

772
/**
773
 * Prepares a string for use as a valid HTML ID and guarantees uniqueness.
774
 *
775 776 777 778 779
 * This function ensures that each passed HTML ID value only exists once on the
 * page. By tracking the already returned ids, this function enables forms,
 * blocks, and other content to be output multiple times on the same page,
 * without breaking (X)HTML validation.
 *
780
 * For already existing IDs, a counter is appended to the ID string. Therefore,
781 782 783 784
 * JavaScript and CSS code should not rely on any value that was generated by
 * this function and instead should rely on manually added CSS classes or
 * similarly reliable constructs.
 *
785 786
 * Two consecutive hyphens separate the counter from the original ID. To manage
 * uniqueness across multiple Ajax requests on the same page, Ajax requests
787 788 789
 * POST an array of all IDs currently present on the page, which are used to
 * prime this function's cache upon first invocation.
 *
790
 * To allow reverse-parsing of IDs submitted via Ajax, any multiple consecutive
791 792
 * hyphens in the originally passed $id are replaced with a single hyphen.
 *
793 794
 * @param $id
 *   The ID to clean.
795
 *
796 797
 * @return
 *   The cleaned ID.
798 799 800
 *
 * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0.0.
 *   Use \Drupal\Component\Utility\Html::getUniqueId()
801
 */
802
function drupal_html_id($id) {
803
  return Html::getUniqueId($id);
804 805
}

806 807 808 809 810 811 812 813 814 815 816 817 818
/**
 * Prepares a string for use as a valid HTML ID.
 *
 * Only use this function when you want to intentionally skip the uniqueness
 * guarantee of drupal_html_id().
 *
 * @param string $id
 *   The ID to clean.
 *
 * @return string
 *   The cleaned ID.
 *
 * @see drupal_html_id()
819 820 821
 *
 * @deprecated in Drupal 8.x-dev, will be removed before Drupal 8.0.0.
 *   Use \Drupal\Component\Utility\Html::getId()
822 823
 */
function drupal_clean_id_identifier($id) {
824
  return Html::getId($id);
825 826
}

827
/**
828
 * Constructs an array of the defaults that are used for JavaScript assets.
829 830
 *
 * @param $data
831
 *   (optional) The default data parameter for the JavaScript asset array.
832
 *
833
 * @see hook_js_alter()
834 835 836 837
 */
function drupal_js_defaults($data = NULL) {
  return array(
    'type' => 'file',
838 839 840
    'group' => JS_DEFAULT,
    'every_page' => FALSE,
    'weight' => 0,
841 842
    'scope' => 'header',
    'cache' => TRUE,
843
    'preprocess' => TRUE,
844
    'attributes' => array(),
845
    'version' => NULL,
846
    'data' => $data,
847
    'browsers' => array(),
848 849 850
  );
}

851
/**
852
 * Merges two #attached arrays.
853
 *
854 855
 * The values under the 'drupalSettings' key are merged in a special way, to
 * match the behavior of
856 857 858 859 860
 *
 * @code
 *   jQuery.extend(true, {}, $settings_items[0], $settings_items[1], ...)
 * @endcode
 *
861
 * This means integer indices are preserved just like string indices are,
862 863 864 865
 * rather than re-indexed as is common in PHP array merging.
 *
 * Example:
 * @code
866
 * function module1_page_attachments(&$page) {
867
 *   $page['a']['#attached']['drupalSettings']['foo'] = ['a', 'b', 'c'];
868
 * }
869
 * function module2_page_attachments(&$page) {
870
 *   $page['#attached']['drupalSettings']['foo'] = ['d'];
871 872 873 874 875 876 877 878
 * }
 * // When the page is rendered after the above code, and the browser runs the
 * // resulting <SCRIPT> tags, the value of drupalSettings.foo is
 * // ['d', 'b', 'c'], not ['a', 'b', 'c', 'd'].
 * @endcode
 *
 * By following jQuery.extend() merge logic rather than common PHP array merge
 * logic, the following are ensured:
879 880
 * - Attaching JavaScript settings is idempotent: attaching the same settings
 *   twice does not change the output sent to the browser.
881 882 883 884
 * - If pieces of the page are rendered in separate PHP requests and the
 *   returned settings are merged by JavaScript, the resulting settings are the
 *   same as if rendered in one PHP request and merged by PHP.
 *
885 886 887 888 889 890 891 892 893
 * @param array $a
 *   An #attached array.
 * @param array $b
 *   Another #attached array.
 *
 * @return array
 *   The merged #attached array.
 */
function drupal_merge_attached(array $a, array $b) {
894 895 896 897 898 899
  // If both #attached arrays contain drupalSettings, then merge them correctly;
  // adding the same settings multiple times needs to behave idempotently.
  if (!empty($a['drupalSettings']) && !empty($b['drupalSettings'])) {
    $a['drupalSettings'] = NestedArray::mergeDeepArray([$a['drupalSettings'], $b['drupalSettings']], TRUE);
    unset($b['drupalSettings']);
  }
900 901 902
  return NestedArray::mergeDeep($a, $b);
}

903
/**
904
 * Processes non-asset attachments in a render() structure.
905
 *
906 907 908 909
 * Libraries, JavaScript settings, feeds, HTML <head> tags and HTML <head> links
 * are attached to elements using the #attached property. The #attached property
 * is an associative array, where the keys are the attachment types and the
 * values are the attached data. For example:
910
 *
911
 * @code
912 913 914
 * $build['#attached'] = [
 *   'library' => ['core/jquery']
 * ];
915 916 917
 * $build['#attached']['http_header'] = [
 *   ['Content-Type', 'application/rss+xml; charset=utf-8'],
 * ];
918 919
 * @endcode
 *
920 921 922 923 924 925 926 927
 * The available keys are:
 * - 'library' (asset libraries)
 * - 'drupalSettings' (JavaScript settings)
 * - 'feed' (RSS feeds)
 * - 'html_head' (tags in HTML <head>)
 * - 'html_head_link' (<link> tags in HTML <head>)
 * - 'http_header' (HTTP headers)
 *
928 929
 * This function processes all non-asset attachments, to apply them to the
 * current response (that means all keys except 'library' and 'drupalSettings').
930
 *
931
 * @param array $elements
932
 *   The structured array describing the data being rendered.
933
 *
934
 * @see drupal_render()
935 936 937 938
 * @see \Drupal\Core\Asset\AssetResolver
 *
 * @throws LogicException
 *   When attaching something of a non-existing attachment type.
939
 */
940 941 942 943
function drupal_process_attached(array $elements) {
  // Asset attachments are handled by \Drupal\Core\Asset\AssetResolver.
  foreach (array('library', 'drupalSettings') as $type) {
    unset($elements['#attached'][$type]);
944 945
  }

946 947
  // Add additional types of attachments specified in the render() structure.
  foreach ($elements['#attached'] as $callback => $options) {
948
    foreach ($elements['#attached'][$callback] as $args) {
949 950 951 952 953 954
      // Limit the amount allowed entries.
      switch ($callback) {
        case 'html_head':
          call_user_func_array('_drupal_add_html_head', $args);
          break;
        case 'feed':
955 956 957 958 959 960 961
          $args = [[
            'href' => $args[0],
            'rel' => 'alternate',
            'title' => $args[1],
            'type' => 'application/rss+xml',
          ]];
          call_user_func_array('_drupal_add_html_head_link', $args);
962 963 964 965 966 967 968 969 970 971
          break;
        case 'html_head_link':
          call_user_func_array('_drupal_add_html_head_link', $args);
          break;
        case 'http_header':
          call_user_func_array('_drupal_add_http_header', $args);
          break;
        default:
          throw new \LogicException(sprintf('You are not allowed to use %s in #attached', $callback));
      }
972
    }
973 974 975
  }
}

976
/**
977
 * Adds JavaScript to change the state of an element based on another element.
978
 *
979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
 * A "state" means a certain property on a DOM element, such as "visible" or
 * "checked". A state can be applied to an element, depending on the state of
 * another element on the page. In general, states depend on HTML attributes and
 * DOM element properties, which change due to user interaction.
 *
 * Since states are driven by JavaScript only, it is important to understand
 * that all states are applied on presentation only, none of the states force
 * any server-side logic, and that they will not be applied for site visitors
 * without JavaScript support. All modules implementing states have to make
 * sure that the intended logic also works without JavaScript being enabled.
 *
 * #states is an associative array in the form of:
 * @code
 * array(
 *   STATE1 => CONDITIONS_ARRAY1,
 *   STATE2 => CONDITIONS_ARRAY2,
 *   ...
 * )
 * @endcode
 * Each key is the name of a state to apply to the element, such as 'visible'.
 * Each value is a list of conditions that denote when the state should be
 * applied.
 *
 * Multiple different states may be specified to act on complex conditions:
 * @code
 * array(
 *   'visible' => CONDITIONS,
 *   'checked' => OTHER_CONDITIONS,
 * )
 * @endcode
 *
 * Every condition is a key/value pair, whose key is a jQuery selector that
 * denotes another element on the page, and whose value is an array of
 * conditions, which must bet met on that element:
 * @code
 * array(
 *   'visible' => array(
 *     JQUERY_SELECTOR => REMOTE_CONDITIONS,
 *     JQUERY_SELECTOR => REMOTE_CONDITIONS,
 *     ...
 *   ),
 * )
 * @endcode
 * All conditions must be met for the state to be applied.
 *
 * Each remote condition is a key/value pair specifying conditions on the other
 * element that need to be met to apply the state to the element:
 * @code
 * array(
 *   'visible' => array(
 *     ':input[name="remote_checkbox"]' => array('checked' => TRUE),
 *   ),
 * )
 * @endcode
 *
 * For example, to show a textfield only when a checkbox is checked:
 * @code
 * $form['toggle_me'] = array(
 *   '#type' => 'checkbox',
 *   '#title' => t('Tick this box to type'),
 * );
 * $form['settings'] = array(
 *   '#type' => 'textfield',
 *   '#states' => array(
 *     // Only show this field when the 'toggle_me' checkbox is enabled.
 *     'visible' => array(
 *       ':input[name="toggle_me"]' => array('checked' => TRUE),
1046
 *     ),
1047 1048 1049 1050 1051 1052 1053
 *   ),
 * );
 * @endcode
 *
 * The following states may be applied to an element:
 * - enabled
 * - disabled
1054 1055
 * - required
 * - optional
1056 1057 1058 1059 1060 1061 1062 1063
 * - visible
 * - invisible
 * - checked
 * - unchecked
 * - expanded
 * - collapsed
 *
 * The following states may be used in remote conditions:
1064 1065
 * - empty
 * - filled
1066 1067
 * - checked
 * - unchecked
1068 1069
 * - expanded
 * - collapsed
1070 1071
 * - value
 *
1072 1073
 * The following states exist for both elements and remote conditions, but are
 * not fully implemented and may not change anything on the element:
1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097
 * - relevant
 * - irrelevant
 * - valid
 * - invalid
 * - touched
 * - untouched
 * - readwrite
 * - readonly
 *
 * When referencing select lists and radio buttons in remote conditions, a
 * 'value' condition must be used:
 * @code
 *   '#states' => array(
 *     // Show the settings if 'bar' has been selected for 'foo'.
 *     'visible' => array(
 *       ':input[name="foo"]' => array('value' => 'bar'),
 *     ),
 *   ),
 * @endcode
 *
 * @param $elements
 *   A renderable array element having a #states property as described above.
 *
 * @see form_example_states_form()
1098 1099
 */
function drupal_process_states(&$elements) {
1100
  $elements['#attached']['library'][] = 'core/drupal.states';
1101 1102 1103 1104 1105 1106
  // Elements of '#type' => 'item' are not actual form input elements, but we
  // still want to be able to show/hide them. Since there's no actual HTML input
  // element available, setting #attributes does not make sense, but a wrapper
  // is available, so setting #wrapper_attributes makes it work.
  $key = ($elements['#type'] == 'item') ? '#wrapper_attributes' : '#attributes';
  $elements[$key]['data-drupal-states'] = JSON::encode($elements['#states']);
1107 1108
}

1109
/**