public static function ActiveLinkResponseFilter::setLinkActiveClass in Drupal 8

Same name and namespace in other branches

9 core/lib/Drupal/Core/EventSubscriber/ActiveLinkResponseFilter.php \Drupal\Core\EventSubscriber\ActiveLinkResponseFilter::setLinkActiveClass()

Sets the "is-active" class on relevant links.

This is a PHP implementation of the drupal.active-link JavaScript library.

@todo Once a future version of PHP supports parsing HTML5 properly (i.e. doesn't fail on https://www.drupal.org/comment/7938201#comment-7938201) then we can get rid of this manual parsing and use DOMDocument instead.

Parameters

string $html_markup: The HTML markup to update.

string $current_path: The system path of the currently active page.

bool $is_front: Whether the current page is the front page (which implies the current path might also be <front>).

string $url_language: The language code of the current URL.

array $query: The query string for the current URL.

Return value

string The updated HTML markup.

2 calls to ActiveLinkResponseFilter::setLinkActiveClass()

ActiveLinkResponseFilter::onResponse in core/lib/Drupal/Core/EventSubscriber/ActiveLinkResponseFilter.php: Sets the 'is-active' class on links.
ActiveLinkResponseFilterTest::testSetLinkActiveClass in core/tests/Drupal/Tests/Core/EventSubscriber/ActiveLinkResponseFilterTest.php: Tests setLinkActiveClass().

File

core/lib/Drupal/Core/EventSubscriber/ActiveLinkResponseFilter.php, line 133

Class

ActiveLinkResponseFilter: Subscribes to filter HTML responses, to set the 'is-active' class on links.

Namespace

Drupal\Core\EventSubscriber

Code

public static function setLinkActiveClass($html_markup, $current_path, $is_front, $url_language, array $query) {
  $search_key_current_path = 'data-drupal-link-system-path="' . $current_path . '"';
  $search_key_front = 'data-drupal-link-system-path="&lt;front&gt;"';

  // Receive the query in a standardized manner.
  ksort($query);
  $offset = 0;

  // There are two distinct conditions that can make a link be marked active:
  // 1. A link has the current path in its 'data-drupal-link-system-path'
  //    attribute.
  // 2. We are on the front page and a link has the special '<front>' value in
  //    its 'data-drupal-link-system-path' attribute.
  while (strpos($html_markup, $search_key_current_path, $offset) !== FALSE || $is_front && strpos($html_markup, $search_key_front, $offset) !== FALSE) {
    $pos_current_path = strpos($html_markup, $search_key_current_path, $offset);

    // Only look for links with the special '<front>' system path if we are
    // actually on the front page.
    $pos_front = $is_front ? strpos($html_markup, $search_key_front, $offset) : FALSE;

    // Determine which of the two values is the next match: the exact path, or
    // the <front> special case.
    $pos_match = NULL;
    if ($pos_front === FALSE) {
      $pos_match = $pos_current_path;
    }
    elseif ($pos_current_path === FALSE) {
      $pos_match = $pos_front;
    }
    elseif ($pos_current_path < $pos_front) {
      $pos_match = $pos_current_path;
    }
    else {
      $pos_match = $pos_front;
    }

    // Find beginning and ending of opening tag.
    $pos_tag_start = NULL;
    for ($i = $pos_match; $pos_tag_start === NULL && $i > 0; $i--) {
      if ($html_markup[$i] === '<') {
        $pos_tag_start = $i;
      }
    }
    $pos_tag_end = NULL;
    for ($i = $pos_match; $pos_tag_end === NULL && $i < strlen($html_markup); $i++) {
      if ($html_markup[$i] === '>') {
        $pos_tag_end = $i;
      }
    }

    // Get the HTML: this will be the opening part of a single tag, e.g.:
    //   <a href="/" data-drupal-link-system-path="&lt;front&gt;">
    $tag = substr($html_markup, $pos_tag_start, $pos_tag_end - $pos_tag_start + 1);

    // Parse it into a DOMDocument so we can reliably read and modify
    // attributes.
    $dom = new \DOMDocument();
    @$dom
      ->loadHTML('<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /></head><body>' . $tag . '</body></html>');
    $node = $dom
      ->getElementsByTagName('body')
      ->item(0)->firstChild;

    // Ensure we don't set the "active" class twice on the same element.
    $class = $node
      ->getAttribute('class');
    $add_active = !in_array('is-active', explode(' ', $class));

    // The language of an active link is equal to the current language.
    if ($add_active && $url_language) {
      if ($node
        ->hasAttribute('hreflang') && $node
        ->getAttribute('hreflang') !== $url_language) {
        $add_active = FALSE;
      }
    }

    // The query parameters of an active link are equal to the current
    // parameters.
    if ($add_active) {
      if ($query) {
        if (!$node
          ->hasAttribute('data-drupal-link-query') || $node
          ->getAttribute('data-drupal-link-query') !== Json::encode($query)) {
          $add_active = FALSE;
        }
      }
      else {
        if ($node
          ->hasAttribute('data-drupal-link-query')) {
          $add_active = FALSE;
        }
      }
    }

    // Only if the path, the language and the query match, we set the
    // "is-active" class.
    if ($add_active) {
      if (strlen($class) > 0) {
        $class .= ' ';
      }
      $class .= 'is-active';
      $node
        ->setAttribute('class', $class);

      // Get the updated tag.
      $updated_tag = $dom
        ->saveXML($node, LIBXML_NOEMPTYTAG);

      // saveXML() added a closing tag, remove it.
      $updated_tag = substr($updated_tag, 0, strrpos($updated_tag, '<'));
      $html_markup = str_replace($tag, $updated_tag, $html_markup);

      // Ensure we only search the remaining HTML.
      $offset = $pos_tag_end - strlen($tag) + strlen($updated_tag);
    }
    else {

      // Ensure we only search the remaining HTML.
      $offset = $pos_tag_end + 1;
    }
  }
  return $html_markup;
}

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