function _filter_url in Drupal 7

Same name and namespace in other branches

8 core/modules/filter/filter.module \_filter_url()
5 modules/filter/filter.module \_filter_url()
6 modules/filter/filter.module \_filter_url()
9 core/modules/filter/filter.module \_filter_url()

Converts text into hyperlinks automatically.

This filter identifies and makes clickable three types of "links".

URLs like http://example.com.
E-mail addresses like name@example.com.
Web addresses without the "http://" protocol defined, like www.example.com.

Each type must be processed separately, as there is no one regular expression that could possibly match all of the cases in one pass.

File

modules/filter/filter.module, line 1456: Framework for handling the filtering of content.

Code

function _filter_url($text, $filter) {

  // Tags to skip and not recurse into.
  $ignore_tags = 'a|script|style|code|pre';

  // Pass length to regexp callback.
  _filter_url_trim(NULL, $filter->settings['filter_url_length']);

  // Create an array which contains the regexps for each type of link.
  // The key to the regexp is the name of a function that is used as
  // callback function to process matches of the regexp. The callback function
  // is to return the replacement for the match. The array is used and
  // matching/replacement done below inside some loops.
  $tasks = array();

  // Prepare protocols pattern for absolute URLs.
  // check_url() will replace any bad protocols with HTTP, so we need to support
  // the identical list. While '//' is technically optional for MAILTO only,
  // we cannot cleanly differ between protocols here without hard-coding MAILTO,
  // so '//' is optional for all protocols.
  // @see filter_xss_bad_protocol()
  $protocols = variable_get('filter_allowed_protocols', array(
    'ftp',
    'http',
    'https',
    'irc',
    'mailto',
    'news',
    'nntp',
    'rtsp',
    'sftp',
    'ssh',
    'tel',
    'telnet',
    'webcal',
  ));
  $protocols = implode(':(?://)?|', $protocols) . ':(?://)?';

  // Prepare domain name pattern.
  // The ICANN seems to be on track towards accepting more diverse top level
  // domains, so this pattern has been "future-proofed" to allow for TLDs
  // of length 2-64.
  $domain = '(?:[A-Za-z0-9._+-]+\\.)?[A-Za-z]{2,64}\\b';
  $ip = '(?:[0-9]{1,3}\\.){3}[0-9]{1,3}';
  $auth = '[a-zA-Z0-9:%_+*~#?&=.,/;-]+@';
  $trail = '[a-zA-Z0-9:%_+*~#&\\[\\]=/;?!\\.,-]*[a-zA-Z0-9:%_+*~#&\\[\\]=/;-]';

  // Prepare pattern for optional trailing punctuation.
  // Even these characters could have a valid meaning for the URL, such usage is
  // rare compared to using a URL at the end of or within a sentence, so these
  // trailing characters are optionally excluded.
  $punctuation = '[\\.,?!]*?';

  // Match absolute URLs.
  $url_pattern = "(?:{$auth})?(?:{$domain}|{$ip})/?(?:{$trail})?";
  $pattern = "`((?:{$protocols})(?:{$url_pattern}))({$punctuation})`";
  $tasks['_filter_url_parse_full_links'] = $pattern;

  // Match e-mail addresses.
  $url_pattern = "[A-Za-z0-9._+-]{1,254}@(?:{$domain})";
  $pattern = "`({$url_pattern})`";
  $tasks['_filter_url_parse_email_links'] = $pattern;

  // Match www domains.
  $url_pattern = "www\\.(?:{$domain})/?(?:{$trail})?";
  $pattern = "`({$url_pattern})({$punctuation})`";
  $tasks['_filter_url_parse_partial_links'] = $pattern;

  // Each type of URL needs to be processed separately. The text is joined and
  // re-split after each task, since all injected HTML tags must be correctly
  // protected before the next task.
  foreach ($tasks as $task => $pattern) {

    // HTML comments need to be handled separately, as they may contain HTML
    // markup, especially a '>'. Therefore, remove all comment contents and add
    // them back later.
    _filter_url_escape_comments('', TRUE);
    $text = preg_replace_callback('`<!--(.*?)-->`s', '_filter_url_escape_comments', $text);

    // Split at all tags; ensures that no tags or attributes are processed.
    $chunks = preg_split('/(<.+?>)/is', $text, -1, PREG_SPLIT_DELIM_CAPTURE);

    // PHP ensures that the array consists of alternating delimiters and
    // literals, and begins and ends with a literal (inserting NULL as
    // required). Therefore, the first chunk is always text:
    $chunk_type = 'text';

    // If a tag of $ignore_tags is found, it is stored in $open_tag and only
    // removed when the closing tag is found. Until the closing tag is found,
    // no replacements are made.
    $open_tag = '';
    for ($i = 0; $i < count($chunks); $i++) {
      if ($chunk_type == 'text') {

        // Only process this text if there are no unclosed $ignore_tags.
        if ($open_tag == '') {

          // If there is a match, inject a link into this chunk via the callback
          // function contained in $task.
          $chunks[$i] = preg_replace_callback($pattern, $task, $chunks[$i]);
        }

        // Text chunk is done, so next chunk must be a tag.
        $chunk_type = 'tag';
      }
      else {

        // Only process this tag if there are no unclosed $ignore_tags.
        if ($open_tag == '') {

          // Check whether this tag is contained in $ignore_tags.
          if (preg_match("`<({$ignore_tags})(?:\\s|>)`i", $chunks[$i], $matches)) {
            $open_tag = $matches[1];
          }
        }
        else {
          if (preg_match("`<\\/{$open_tag}>`i", $chunks[$i], $matches)) {
            $open_tag = '';
          }
        }

        // Tag chunk is done, so next chunk must be text.
        $chunk_type = 'text';
      }
    }
    $text = implode($chunks);

    // Revert back to the original comment contents
    _filter_url_escape_comments('', FALSE);
    $text = preg_replace_callback('`<!--(.*?)-->`', '_filter_url_escape_comments', $text);
  }
  return $text;
}

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function _filter_url in Drupal 7

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