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41 results

common.inc

Blame
  • webchick's avatar
    Issue #1222794 by gapple, jhodgdon: Fixed drupal_add_css() support for stream...
    Angie Byron authored
    Issue #1222794 by gapple, jhodgdon: Fixed drupal_add_css() support for stream wrappers not documented.
    aa4fbf26
    History
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    Assign users and groups as approvers for specific file changes. Learn more.
    common.inc 284.12 KiB
    <?php
    
    /**
     * @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.
     */
    
    /**
     * @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
     *   $my_substring = drupal_substr($original_string, 0, 5);
     * @endcode
     *
     * @}
     */
    
    /**
     * Return status for saving which involved creating a new item.
     */
    define('SAVED_NEW', 1);
    
    /**
     * Return status for saving which involved an update to an existing item.
     */
    define('SAVED_UPDATED', 2);
    
    /**
     * Return status for saving which deleted an existing item.
     */
    define('SAVED_DELETED', 3);
    
    /**
     * The default group for system CSS files added to the page.
     */
    define('CSS_SYSTEM', -100);
    
    /**
     * The default group for module CSS files added to the page.
     */
    define('CSS_DEFAULT', 0);
    
    /**
     * The default group for theme CSS files added to the page.
     */
    define('CSS_THEME', 100);
    
    /**
     * The default group for JavaScript libraries, settings or jQuery plugins added
     * to the page.
     */
    define('JS_LIBRARY', -100);
    
    /**
     * The default group for module JavaScript code added to the page.
     */
    define('JS_DEFAULT', 0);
    
    /**
     * The default group for theme JavaScript code added to the page.
     */
    define('JS_THEME', 100);
    
    /**
     * Error code indicating that the request made by drupal_http_request() exceeded
     * the specified timeout.
     */
    define('HTTP_REQUEST_TIMEOUT', 1);
    
    /**
     * Constants defining cache granularity for blocks and renderable arrays.
     *
     * Modules specify the caching patterns for their blocks using binary
     * combinations of these constants in their hook_block_info():
     *   $block[delta]['cache'] = DRUPAL_CACHE_PER_ROLE | DRUPAL_CACHE_PER_PAGE;
     * DRUPAL_CACHE_PER_ROLE is used as a default when no caching pattern is
     * specified. Use DRUPAL_CACHE_CUSTOM to disable standard block cache and
     * implement
     *
     * The block cache is cleared in cache_clear_all(), and uses the same clearing
     * policy than page cache (node, comment, user, taxonomy added or updated...).
     * Blocks requiring more fine-grained clearing might consider disabling the
     * built-in block cache (DRUPAL_NO_CACHE) and roll their own.
     *
     * Note that user 1 is excluded from block caching.
     */
    
    /**
     * The block should not get cached. This setting should be used:
     * - for simple blocks (notably those that do not perform any db query),
     * where querying the db cache would be more expensive than directly generating
     * the content.
     * - for blocks that change too frequently.
     */
    define('DRUPAL_NO_CACHE', -1);
    
    /**
     * The block is handling its own caching in its hook_block_view(). From the
     * perspective of the block cache system, this is equivalent to DRUPAL_NO_CACHE.
     * Useful when time based expiration is needed or a site uses a node access
     * which invalidates standard block cache.
     */
    define('DRUPAL_CACHE_CUSTOM', -2);
    
    /**
     * The block or element can change depending on the roles the user viewing the
     * page belongs to. This is the default setting for blocks, used when the block
     * does not specify anything.
     */
    define('DRUPAL_CACHE_PER_ROLE', 0x0001);
    
    /**
     * The block or element can change depending on the user viewing the page.
     * This setting can be resource-consuming for sites with large number of users,
     * and thus should only be used when DRUPAL_CACHE_PER_ROLE is not sufficient.
     */
    define('DRUPAL_CACHE_PER_USER', 0x0002);
    
    /**
     * The block or element can change depending on the page being viewed.
     */
    define('DRUPAL_CACHE_PER_PAGE', 0x0004);
    
    /**
     * The block or element is the same for every user on every page where it is visible.
     */
    define('DRUPAL_CACHE_GLOBAL', 0x0008);
    
    /**
     * Add content to a specified region.
     *
     * @param $region
     *   Page region the content is added to.
     * @param $data
     *   Content to be added.
     */
    function drupal_add_region_content($region = NULL, $data = NULL) {
      static $content = array();
    
      if (isset($region) && isset($data)) {
        $content[$region][] = $data;
      }
      return $content;
    }
    
    /**
     * Get assigned content for a given region.
     *
     * @param $region
     *   A specified region to fetch content for. If NULL, all regions will be
     *   returned.
     * @param $delimiter
     *   Content to be inserted between imploded array elements.
     */
    function drupal_get_region_content($region = NULL, $delimiter = ' ') {
      $content = drupal_add_region_content();
      if (isset($region)) {
        if (isset($content[$region]) && is_array($content[$region])) {
          return implode($delimiter, $content[$region]);
        }
      }
      else {
        foreach (array_keys($content) as $region) {
          if (is_array($content[$region])) {
            $content[$region] = implode($delimiter, $content[$region]);
          }
        }
        return $content;
      }
    }
    
    /**
     * Get the name of the currently active install profile.
     *
     * When this function is called during Drupal's initial installation process,
     * the name of the profile that's about to be installed is stored in the global
     * installation state. At all other times, the standard Drupal systems variable
     * table contains the name of the current profile, and we can call variable_get()
     * to determine what one is active.
     *
     * @return $profile
     *   The name of the install profile.
     */
    function drupal_get_profile() {
      global $install_state;
    
      if (isset($install_state['parameters']['profile'])) {
        $profile = $install_state['parameters']['profile'];
      }
      else {
        $profile = variable_get('install_profile', 'standard');
      }
    
      return $profile;
    }
    
    
    /**
     * Set the breadcrumb trail for the current page.
     *
     * @param $breadcrumb
     *   Array of links, starting with "home" and proceeding up to but not including
     *   the current page.
     */
    function drupal_set_breadcrumb($breadcrumb = NULL) {
      $stored_breadcrumb = &drupal_static(__FUNCTION__);
    
      if (isset($breadcrumb)) {
        $stored_breadcrumb = $breadcrumb;
      }
      return $stored_breadcrumb;
    }
    
    /**
     * Get the breadcrumb trail for the current page.
     */
    function drupal_get_breadcrumb() {
      $breadcrumb = drupal_set_breadcrumb();
    
      if (!isset($breadcrumb)) {
        $breadcrumb = menu_get_active_breadcrumb();
      }
    
      return $breadcrumb;
    }
    
    /**
     * Returns a string containing RDF namespace declarations for use in XML and
     * XHTML output.
     */
    function drupal_get_rdf_namespaces() {
      $xml_rdf_namespaces = array();
    
      // Serializes the RDF namespaces in XML namespace syntax.
      if (function_exists('rdf_get_namespaces')) {
        foreach (rdf_get_namespaces() as $prefix => $uri) {
          $xml_rdf_namespaces[] = 'xmlns:' . $prefix . '="' . $uri . '"';
        }
      }
      return count($xml_rdf_namespaces) ? "\n  " . implode("\n  ", $xml_rdf_namespaces) : '';
    }
    
    /**
     * Add output to the head tag of the HTML page.
     *
     * This function can be called as long the headers aren't sent. Pass no
     * 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 $data is not NULL.
     *
     * @return
     *   An array of all stored HEAD elements.
     *
     * @see theme_html_tag()
     */
    function drupal_add_html_head($data = NULL, $key = NULL) {
      $stored_head = &drupal_static(__FUNCTION__);
    
      if (!isset($stored_head)) {
        // Make sure the defaults, including Content-Type, come first.
        $stored_head = _drupal_default_html_head();
      }
    
      if (isset($data) && isset($key)) {
        if (!isset($data['#type'])) {
          $data['#type'] = 'html_tag';
        }
        $stored_head[$key] = $data;
      }
      return $stored_head;
    }
    
    /**
     * Returns elements that are always displayed in the HEAD tag of the HTML page.
     */
    function _drupal_default_html_head() {
      // Add default elements. Make sure the Content-Type comes first because the
      // IE browser may be vulnerable to XSS via encoding attacks from any content
      // that comes before this META tag, such as a TITLE tag.
      $elements['system_meta_content_type'] = array(
        '#type' => 'html_tag',
        '#tag' => 'meta',
        '#attributes' => array(
          'http-equiv' => 'Content-Type',
          'content' => 'text/html; charset=utf-8',
        ),
        // Security: This always has to be output first.
        '#weight' => -1000,
      );
      // Show Drupal and the major version number in the META GENERATOR tag.
      // Get the major version.
      list($version, ) = explode('.', VERSION);
      $elements['system_meta_generator'] = array(
        '#type' => 'html_tag',
        '#tag' => 'meta',
        '#attributes' => array(
          'name' => 'Generator',
          'content' => 'Drupal ' . $version . ' (http://drupal.org)',
        ),
      );
      // Also send the generator in the HTTP header.
      $elements['system_meta_generator']['#attached']['drupal_add_http_header'][] = array('X-Generator', $elements['system_meta_generator']['#attributes']['content']);
      return $elements;
    }
    
    /**
     * Retrieve output to be displayed in the HEAD tag of the HTML page.
     */
    function drupal_get_html_head() {
      $elements = drupal_add_html_head();
      drupal_alter('html_head', $elements);
      return drupal_render($elements);
    }
    
    /**
     * Add a feed URL for the current page.
     *
     * This function can be called as long the HTML header hasn't been sent.
     *
     * @param $url
     *   An internal system path or a fully qualified external URL of the feed.
     * @param $title
     *   The title of the feed.
     */
    function drupal_add_feed($url = NULL, $title = '') {
      $stored_feed_links = &drupal_static(__FUNCTION__, array());
    
      if (isset($url)) {
        $stored_feed_links[$url] = theme('feed_icon', array('url' => $url, 'title' => $title));
    
        drupal_add_html_head_link(array(
          'rel' => 'alternate',
          'type' => 'application/rss+xml',
          'title' => $title,
          // Force the URL to be absolute, for consistency with other <link> tags
          // output by Drupal.
          'href' => url($url, array('absolute' => TRUE)),
        ));
      }
      return $stored_feed_links;
    }
    
    /**
     * Get the feed URLs for the current page.
     *
     * @param $delimiter
     *   A delimiter to split feeds by.
     */
    function drupal_get_feeds($delimiter = "\n") {
      $feeds = drupal_add_feed();
      return implode($feeds, $delimiter);
    }
    
    /**
     * @defgroup http_handling HTTP handling
     * @{
     * Functions to properly handle HTTP responses.
     */
    
    /**
     * Process a URL query parameter array to remove unwanted elements.
     *
     * @param $query
     *   (optional) An array to be processed. Defaults to $_GET.
     * @param $exclude
     *   (optional) A list of $query array keys to remove. Use "parent[child]" to
     *   exclude nested items. Defaults to array('q').
     * @param $parent
     *   Internal use only. Used to build the $query array key for nested items.
     *
     * @return
     *   An array containing query parameters, which can be used for url().
     */
    function drupal_get_query_parameters(array $query = NULL, array $exclude = array('q'), $parent = '') {
      // Set defaults, if none given.
      if (!isset($query)) {
        $query = $_GET;
      }
      // If $exclude is empty, there is nothing to filter.
      if (empty($exclude)) {
        return $query;
      }
      elseif (!$parent) {
        $exclude = array_flip($exclude);
      }
    
      $params = array();
      foreach ($query as $key => $value) {
        $string_key = ($parent ? $parent . '[' . $key . ']' : $key);
        if (isset($exclude[$string_key])) {
          continue;
        }
    
        if (is_array($value)) {
          $params[$key] = drupal_get_query_parameters($value, $exclude, $string_key);
        }
        else {
          $params[$key] = $value;
        }
      }
    
      return $params;
    }
    
    /**
     * Split an URL-encoded query string into an array.
     *
     * @param $query
     *   The query string to split.
     *
     * @return
     *   An array of url decoded couples $param_name => $value.
     */
    function drupal_get_query_array($query) {
      $result = array();
      if (!empty($query)) {
        foreach (explode('&', $query) as $param) {
          $param = explode('=', $param);
          $result[$param[0]] = isset($param[1]) ? rawurldecode($param[1]) : '';
        }
      }
      return $result;
    }
    
    /**
     * Parse an array into a valid, rawurlencoded query string.
     *
     * This differs from http_build_query() as we need to rawurlencode() (instead of
     * urlencode()) all query parameters.
     *
     * @param $query
     *   The query parameter array to be processed, e.g. $_GET.
     * @param $parent
     *   Internal use only. Used to build the $query array key for nested items.
     *
     * @return
     *   A rawurlencoded string which can be used as or appended to the URL query
     *   string.
     *
     * @see drupal_get_query_parameters()
     * @ingroup php_wrappers
     */
    function drupal_http_build_query(array $query, $parent = '') {
      $params = array();
    
      foreach ($query as $key => $value) {
        $key = ($parent ? $parent . '[' . rawurlencode($key) . ']' : rawurlencode($key));
    
        // Recurse into children.
        if (is_array($value)) {
          $params[] = drupal_http_build_query($value, $key);
        }
        // If a query parameter value is NULL, only append its key.
        elseif (!isset($value)) {
          $params[] = $key;
        }
        else {
          // For better readability of paths in query strings, we decode slashes.
          $params[] = $key . '=' . str_replace('%2F', '/', rawurlencode($value));
        }
      }
    
      return implode('&', $params);
    }
    
    /**
     * Prepare a 'destination' URL query parameter for use in combination with drupal_goto().
     *
     * 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.
     *
     * @see drupal_goto()
     */
    function drupal_get_destination() {
      $destination = &drupal_static(__FUNCTION__);
    
      if (isset($destination)) {
        return $destination;
      }
    
      if (isset($_GET['destination'])) {
        $destination = array('destination' => $_GET['destination']);
      }
      else {
        $path = $_GET['q'];
        $query = drupal_http_build_query(drupal_get_query_parameters());
        if ($query != '') {
          $path .= '?' . $query;
        }
        $destination = array('destination' => $path);
      }
      return $destination;
    }
    
    /**
     * Wrapper around parse_url() to parse a system URL string into an associative array, suitable for url().
     *
     * This function should only be used for URLs that have been generated by the
     * system, resp. url(). It should not be used for URLs that come from external
     * sources, or URLs that link to external resources.
     *
     * The returned array contains a 'path' that may be passed separately to url().
     * For example:
     * @code
     *   $options = drupal_parse_url($_GET['destination']);
     *   $my_url = url($options['path'], $options);
     *   $my_link = l('Example link', $options['path'], $options);
     * @endcode
     *
     * This is required, because url() does not support relative URLs containing a
     * query string or fragment in its $path argument. Instead, any query string
     * needs to be parsed into an associative query parameter array in
     * $options['query'] and the fragment into $options['fragment'].
     *
     * @param $url
     *   The URL string to parse, f.e. $_GET['destination'].
     *
     * @return
     *   An associative array containing the keys:
     *   - 'path': The path of the URL. If the given $url is external, this includes
     *     the scheme and host.
     *   - 'query': An array of query parameters of $url, if existent.
     *   - 'fragment': The fragment of $url, if existent.
     *
     * @see url()
     * @see drupal_goto()
     * @ingroup php_wrappers
     */
    function drupal_parse_url($url) {
      $options = array(
        'path' => NULL,
        'query' => array(),
        'fragment' => '',
      );
    
      // External URLs: not using parse_url() here, so we do not have to rebuild
      // the scheme, host, and path without having any use for it.
      if (strpos($url, '://') !== FALSE) {
        // Split off everything before the query string into 'path'.
        $parts = explode('?', $url);
        $options['path'] = $parts[0];
        // If there is a query string, transform it into keyed query parameters.
        if (isset($parts[1])) {
          $query_parts = explode('#', $parts[1]);
          parse_str($query_parts[0], $options['query']);
          // Take over the fragment, if there is any.
          if (isset($query_parts[1])) {
            $options['fragment'] = $query_parts[1];
          }
        }
      }
      // Internal URLs.
      else {
        // parse_url() does not support relative URLs, so make it absolute. E.g. the
        // relative URL "foo/bar:1" isn't properly parsed.
        $parts = parse_url('http://example.com/' . $url);
        // Strip the leading slash that was just added.
        $options['path'] = substr($parts['path'], 1);
        if (isset($parts['query'])) {
          parse_str($parts['query'], $options['query']);
        }
        if (isset($parts['fragment'])) {
          $options['fragment'] = $parts['fragment'];
        }
      }
      // The 'q' parameter contains the path of the current page if clean URLs are
      // disabled. It overrides the 'path' of the URL when present, even if clean
      // URLs are enabled, due to how Apache rewriting rules work.
      if (isset($options['query']['q'])) {
        $options['path'] = $options['query']['q'];
        unset($options['query']['q']);
      }
    
      return $options;
    }
    
    /**
     * Encodes a Drupal path for use in a URL.
     *
     * For aesthetic reasons slashes are not escaped.
     *
     * Note that url() takes care of calling this function, so a path passed to that
     * function should not be encoded in advance.
     *
     * @param $path
     *   The Drupal path to encode.
     */
    function drupal_encode_path($path) {
      return str_replace('%2F', '/', rawurlencode($path));
    }
    
    /**
     * Send the user to a different Drupal page.
     *
     * This issues an on-site HTTP redirect. The function makes sure the redirected
     * URL is formatted correctly.
     *
     * If a destination was specified in the current request's URI (i.e.,
     * $_GET['destination']) then it will override the $path and $options values
     * passed to this function. This provides the flexibility to build a link to
     * user/login and override the default redirection so that the user is
     * redirected to a specific path after logging in:
     * @code
     *   $query = array('destination' => "node/$node->nid");
     *   $link = l(t('Log in'), 'user/login', array('query' => $query));
     * @endcode
     *
     * Drupal will ensure that messages set by drupal_set_message() and other
     * session data are written to the database before the user is redirected.
     *
     * This function ends the request; use it instead of a return in your menu
     * callback.
     *
     * @param $path
     *   A Drupal path or a full URL.
     * @param $options
     *   An associative array of additional URL options to pass to url().
     * @param $http_response_code
     *   Valid values for an actual "goto" as per RFC 2616 section 10.3 are:
     *   - 301 Moved Permanently (the recommended value for most redirects)
     *   - 302 Found (default in Drupal and PHP, sometimes used for spamming search
     *         engines)
     *   - 303 See Other
     *   - 304 Not Modified
     *   - 305 Use Proxy
     *   - 307 Temporary Redirect (alternative to "503 Site Down for Maintenance")
     *   Note: Other values are defined by RFC 2616, but are rarely used and poorly
     *   supported.
     *
     * @see drupal_get_destination()
     * @see url()
     */
    function drupal_goto($path = '', array $options = array(), $http_response_code = 302) {
      // A destination in $_GET always overrides the function arguments.
      // We do not allow absolute URLs to be passed via $_GET, as this can be an attack vector.
      if (isset($_GET['destination']) && !url_is_external($_GET['destination'])) {
        $destination = drupal_parse_url($_GET['destination']);
        $path = $destination['path'];
        $options['query'] = $destination['query'];
        $options['fragment'] = $destination['fragment'];
      }
    
      drupal_alter('drupal_goto', $path, $options, $http_response_code);
    
      // The 'Location' HTTP header must be absolute.
      $options['absolute'] = TRUE;
    
      $url = url($path, $options);
    
      header('Location: ' . $url, TRUE, $http_response_code);
    
      // The "Location" header sends a redirect status code to the HTTP daemon. In
      // some cases this can be wrong, so we make sure none of the code below the
      // drupal_goto() call gets executed upon redirection.
      drupal_exit($url);
    }
    
    /**
     * Deliver a "site is under maintenance" message to the browser.
     *
     * Page callback functions wanting to report a "site offline" message should
     * return MENU_SITE_OFFLINE instead of calling drupal_site_offline(). However,
     * functions that are invoked in contexts where that return value might not
     * bubble up to menu_execute_active_handler() should call drupal_site_offline().
     */
    function drupal_site_offline() {
      drupal_deliver_page(MENU_SITE_OFFLINE);
    }
    
    /**
     * Deliver a "page not found" error to the browser.
     *
     * Page callback functions wanting to report a "page not found" message should
     * return MENU_NOT_FOUND instead of calling drupal_not_found(). However,
     * functions that are invoked in contexts where that return value might not
     * bubble up to menu_execute_active_handler() should call drupal_not_found().
     */
    function drupal_not_found() {
      drupal_deliver_page(MENU_NOT_FOUND);
    }
    
    /**
     * Deliver a "access denied" error to the browser.
     *
     * Page callback functions wanting to report an "access denied" message should
     * return MENU_ACCESS_DENIED instead of calling drupal_access_denied(). However,
     * functions that are invoked in contexts where that return value might not
     * bubble up to menu_execute_active_handler() should call drupal_access_denied().
     */
    function drupal_access_denied() {
      drupal_deliver_page(MENU_ACCESS_DENIED);
    }
    
    /**
     * Perform an HTTP request.
     *
     * This is a flexible and powerful HTTP client implementation. Correctly
     * handles GET, POST, PUT or any other HTTP requests. Handles redirects.
     *
     * @param $url
     *   A string containing a fully qualified URI.
     * @param array $options
     *   (optional) An array that can have one or more of the following elements:
     *   - headers: An array containing request headers to send as name/value pairs.
     *   - method: A string containing the request method. Defaults to 'GET'.
     *   - data: A string containing the request body, formatted as
     *     'param=value&param=value&...'. Defaults to NULL.
     *   - max_redirects: An integer representing how many times a redirect
     *     may be followed. Defaults to 3.
     *   - timeout: A float representing the maximum number of seconds the function
     *     call may take. The default is 30 seconds. If a timeout occurs, the error
     *     code is set to the HTTP_REQUEST_TIMEOUT constant.
     *   - context: A context resource created with stream_context_create().
     *
     * @return object
     *   An object that can have one or more of the following components:
     *   - request: A string containing the request body that was sent.
     *   - code: An integer containing the response status code, or the error code
     *     if an error occurred.
     *   - protocol: The response protocol (e.g. HTTP/1.1 or HTTP/1.0).
     *   - status_message: The status message from the response, if a response was
     *     received.
     *   - redirect_code: If redirected, an integer containing the initial response
     *     status code.
     *   - redirect_url: If redirected, a string containing the URL of the redirect
     *     target.
     *   - error: If an error occurred, the error message. Otherwise not set.
     *   - headers: An array containing the response headers as name/value pairs.
     *     HTTP header names are case-insensitive (RFC 2616, section 4.2), so for
     *     easy access the array keys are returned in lower case.
     *   - data: A string containing the response body that was received.
     */
    function drupal_http_request($url, array $options = array()) {
      $result = new stdClass();
    
      // Parse the URL and make sure we can handle the schema.
      $uri = @parse_url($url);
    
      if ($uri == FALSE) {
        $result->error = 'unable to parse URL';
        $result->code = -1001;
        return $result;
      }
    
      if (!isset($uri['scheme'])) {
        $result->error = 'missing schema';
        $result->code = -1002;
        return $result;
      }
    
      timer_start(__FUNCTION__);
    
      // Merge the default options.
      $options += array(
        'headers' => array(),
        'method' => 'GET',
        'data' => NULL,
        'max_redirects' => 3,
        'timeout' => 30.0,
        'context' => NULL,
      );
      // stream_socket_client() requires timeout to be a float.
      $options['timeout'] = (float) $options['timeout'];
    
      switch ($uri['scheme']) {
        case 'http':
        case 'feed':
          $port = isset($uri['port']) ? $uri['port'] : 80;
          $socket = 'tcp://' . $uri['host'] . ':' . $port;
          // RFC 2616: "non-standard ports MUST, default ports MAY be included".
          // We don't add the standard port to prevent from breaking rewrite rules
          // checking the host that do not take into account the port number.
          $options['headers']['Host'] = $uri['host'] . ($port != 80 ? ':' . $port : '');
          break;
        case 'https':
          // Note: Only works when PHP is compiled with OpenSSL support.
          $port = isset($uri['port']) ? $uri['port'] : 443;
          $socket = 'ssl://' . $uri['host'] . ':' . $port;
          $options['headers']['Host'] = $uri['host'] . ($port != 443 ? ':' . $port : '');
          break;
        default:
          $result->error = 'invalid schema ' . $uri['scheme'];
          $result->code = -1003;
          return $result;
      }
    
      if (empty($options['context'])) {
        $fp = @stream_socket_client($socket, $errno, $errstr, $options['timeout']);
      }
      else {
        // Create a stream with context. Allows verification of a SSL certificate.
        $fp = @stream_socket_client($socket, $errno, $errstr, $options['timeout'], STREAM_CLIENT_CONNECT, $options['context']);
      }
    
      // Make sure the socket opened properly.
      if (!$fp) {
        // When a network error occurs, we use a negative number so it does not
        // clash with the HTTP status codes.
        $result->code = -$errno;
        $result->error = trim($errstr) ? trim($errstr) : t('Error opening socket @socket', array('@socket' => $socket));
    
        // Mark that this request failed. This will trigger a check of the web
        // server's ability to make outgoing HTTP requests the next time that
        // requirements checking is performed.
        // See system_requirements()
        variable_set('drupal_http_request_fails', TRUE);
    
        return $result;
      }
    
      // Construct the path to act on.
      $path = isset($uri['path']) ? $uri['path'] : '/';
      if (isset($uri['query'])) {
        $path .= '?' . $uri['query'];
      }
    
      // Merge the default headers.
      $options['headers'] += array(
        'User-Agent' => 'Drupal (+http://drupal.org/)',
      );
    
      // Only add Content-Length if we actually have any content or if it is a POST
      // or PUT request. Some non-standard servers get confused by Content-Length in
      // at least HEAD/GET requests, and Squid always requires Content-Length in
      // POST/PUT requests.
      $content_length = strlen($options['data']);
      if ($content_length > 0 || $options['method'] == 'POST' || $options['method'] == 'PUT') {
        $options['headers']['Content-Length'] = $content_length;
      }
    
      // If the server URL has a user then attempt to use basic authentication.
      if (isset($uri['user'])) {
        $options['headers']['Authorization'] = 'Basic ' . base64_encode($uri['user'] . (!empty($uri['pass']) ? ":" . $uri['pass'] : ''));
      }
    
      // If the database prefix is being used by SimpleTest to run the tests in a copied
      // database then set the user-agent header to the database prefix so that any
      // calls to other Drupal pages will run the SimpleTest prefixed database. The
      // user-agent is used to ensure that multiple testing sessions running at the
      // same time won't interfere with each other as they would if the database
      // prefix were stored statically in a file or database variable.
      $test_info = &$GLOBALS['drupal_test_info'];
      if (!empty($test_info['test_run_id'])) {
        $options['headers']['User-Agent'] = drupal_generate_test_ua($test_info['test_run_id']);
      }
    
      $request = $options['method'] . ' ' . $path . " HTTP/1.0\r\n";
      foreach ($options['headers'] as $name => $value) {
        $request .= $name . ': ' . trim($value) . "\r\n";
      }
      $request .= "\r\n" . $options['data'];
      $result->request = $request;
      // Calculate how much time is left of the original timeout value.
      $timeout = $options['timeout'] - timer_read(__FUNCTION__) / 1000;
      if ($timeout > 0) {
        stream_set_timeout($fp, floor($timeout), floor(1000000 * fmod($timeout, 1)));
        fwrite($fp, $request);
      }
    
      // Fetch response. Due to PHP bugs like http://bugs.php.net/bug.php?id=43782
      // and http://bugs.php.net/bug.php?id=46049 we can't rely on feof(), but
      // instead must invoke stream_get_meta_data() each iteration.
      $info = stream_get_meta_data($fp);
      $alive = !$info['eof'] && !$info['timed_out'];
      $response = '';
    
      while ($alive) {
        // Calculate how much time is left of the original timeout value.
        $timeout = $options['timeout'] - timer_read(__FUNCTION__) / 1000;
        if ($timeout <= 0) {
          $info['timed_out'] = TRUE;
          break;
        }
        stream_set_timeout($fp, floor($timeout), floor(1000000 * fmod($timeout, 1)));
        $chunk = fread($fp, 1024);
        $response .= $chunk;
        $info = stream_get_meta_data($fp);
        $alive = !$info['eof'] && !$info['timed_out'] && $chunk;
      }
      fclose($fp);
    
      if ($info['timed_out']) {
        $result->code = HTTP_REQUEST_TIMEOUT;
        $result->error = 'request timed out';
        return $result;
      }
      // Parse response headers from the response body.
      // Be tolerant of malformed HTTP responses that separate header and body with
      // \n\n or \r\r instead of \r\n\r\n.
      list($response, $result->data) = preg_split("/\r\n\r\n|\n\n|\r\r/", $response, 2);
      $response = preg_split("/\r\n|\n|\r/", $response);
    
      // Parse the response status line.
      list($protocol, $code, $status_message) = explode(' ', trim(array_shift($response)), 3);
      $result->protocol = $protocol;
      $result->status_message = $status_message;
    
      $result->headers = array();
    
      // Parse the response headers.
      while ($line = trim(array_shift($response))) {
        list($name, $value) = explode(':', $line, 2);
        $name = strtolower($name);
        if (isset($result->headers[$name]) && $name == 'set-cookie') {
          // RFC 2109: the Set-Cookie response header comprises the token Set-
          // Cookie:, followed by a comma-separated list of one or more cookies.
          $result->headers[$name] .= ',' . trim($value);
        }
        else {
          $result->headers[$name] = trim($value);
        }
      }
    
      $responses = array(
        100 => 'Continue',
        101 => 'Switching Protocols',
        200 => 'OK',
        201 => 'Created',
        202 => 'Accepted',
        203 => 'Non-Authoritative Information',
        204 => 'No Content',
        205 => 'Reset Content',
        206 => 'Partial Content',
        300 => 'Multiple Choices',
        301 => 'Moved Permanently',
        302 => 'Found',
        303 => 'See Other',
        304 => 'Not Modified',
        305 => 'Use Proxy',
        307 => 'Temporary Redirect',
        400 => 'Bad Request',
        401 => 'Unauthorized',
        402 => 'Payment Required',
        403 => 'Forbidden',
        404 => 'Not Found',
        405 => 'Method Not Allowed',
        406 => 'Not Acceptable',
        407 => 'Proxy Authentication Required',
        408 => 'Request Time-out',
        409 => 'Conflict',
        410 => 'Gone',
        411 => 'Length Required',
        412 => 'Precondition Failed',
        413 => 'Request Entity Too Large',
        414 => 'Request-URI Too Large',
        415 => 'Unsupported Media Type',
        416 => 'Requested range not satisfiable',
        417 => 'Expectation Failed',
        500 => 'Internal Server Error',
        501 => 'Not Implemented',
        502 => 'Bad Gateway',
        503 => 'Service Unavailable',
        504 => 'Gateway Time-out',
        505 => 'HTTP Version not supported',
      );
      // RFC 2616 states that all unknown HTTP codes must be treated the same as the
      // base code in their class.
      if (!isset($responses[$code])) {
        $code = floor($code / 100) * 100;
      }
      $result->code = $code;
    
      switch ($code) {
        case 200: // OK
        case 304: // Not modified
          break;
        case 301: // Moved permanently
        case 302: // Moved temporarily
        case 307: // Moved temporarily
          $location = $result->headers['location'];
          $options['timeout'] -= timer_read(__FUNCTION__) / 1000;
          if ($options['timeout'] <= 0) {
            $result->code = HTTP_REQUEST_TIMEOUT;
            $result->error = 'request timed out';
          }
          elseif ($options['max_redirects']) {
            // Redirect to the new location.
            $options['max_redirects']--;
            $result = drupal_http_request($location, $options);
            $result->redirect_code = $code;
          }
          if (!isset($result->redirect_url)) {
            $result->redirect_url = $location;
          }
          break;
        default:
          $result->error = $status_message;
      }
    
      return $result;
    }
    /**
     * @} End of "HTTP handling".
     */
    
    function _fix_gpc_magic(&$item) {
      if (is_array($item)) {
        array_walk($item, '_fix_gpc_magic');
      }
      else {
        $item = stripslashes($item);
      }
    }
    
    /**
     * Helper function to strip slashes from $_FILES skipping over the tmp_name keys
     * since PHP generates single backslashes for file paths on Windows systems.
     *
     * tmp_name does not have backslashes added see
     * http://php.net/manual/en/features.file-upload.php#42280
     */
    function _fix_gpc_magic_files(&$item, $key) {
      if ($key != 'tmp_name') {
        if (is_array($item)) {
          array_walk($item, '_fix_gpc_magic_files');
        }
        else {
          $item = stripslashes($item);
        }
      }
    }
    
    /**
     * Fix double-escaping problems caused by "magic quotes" in some PHP installations.
     */
    function fix_gpc_magic() {
      static $fixed = FALSE;
      if (!$fixed && ini_get('magic_quotes_gpc')) {
        array_walk($_GET, '_fix_gpc_magic');
        array_walk($_POST, '_fix_gpc_magic');
        array_walk($_COOKIE, '_fix_gpc_magic');
        array_walk($_REQUEST, '_fix_gpc_magic');
        array_walk($_FILES, '_fix_gpc_magic_files');
      }
      $fixed = TRUE;
    }
    
    /**
     * @defgroup validation Input validation
     * @{
     * Functions to validate user input.
     */
    
    /**
     * Verify the syntax of the given e-mail address.
     *
     * Empty e-mail addresses are allowed. See RFC 2822 for details.
     *
     * @param $mail
     *   A string containing an e-mail address.
     * @return
     *   TRUE if the address is in a valid format.
     */
    function valid_email_address($mail) {
      return (bool)filter_var($mail, FILTER_VALIDATE_EMAIL);
    }
    
    /**
     * Verify the syntax of the given URL.
     *
     * This function should only be used on actual URLs. It should not be used for
     * Drupal menu paths, which can contain arbitrary characters.
     * Valid values per RFC 3986.
     * @param $url
     *   The URL to verify.
     * @param $absolute
     *   Whether the URL is absolute (beginning with a scheme such as "http:").
     * @return
     *   TRUE if the URL is in a valid format.
     */
    function valid_url($url, $absolute = FALSE) {
      if ($absolute) {
        return (bool)preg_match("
          /^                                                      # Start at the beginning of the text
          (?:ftp|https?|feed):\/\/                                # Look for ftp, http, https or feed schemes
          (?:                                                     # Userinfo (optional) which is typically
            (?:(?:[\w\.\-\+!$&'\(\)*\+,;=]|%[0-9a-f]{2})+:)*      # a username or a username and password
            (?:[\w\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})+@          # combination
          )?
          (?:
            (?:[a-z0-9\-\.]|%[0-9a-f]{2})+                        # A domain name or a IPv4 address
            |(?:\[(?:[0-9a-f]{0,4}:)*(?:[0-9a-f]{0,4})\])         # or a well formed IPv6 address
          )
          (?::[0-9]+)?                                            # Server port number (optional)
          (?:[\/|\?]
            (?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})   # The path and query (optional)
          *)?
        $/xi", $url);
      }
      else {
        return (bool)preg_match("/^(?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})+$/i", $url);
      }
    }
    
    /**
     * @} End of "defgroup validation".
     */
    
    /**
     * Register an event for the current visitor to the flood control mechanism.
     *
     * @param $name
     *   The name of an event.
     * @param $window
     *   Optional number of seconds before this event expires. Defaults to 3600 (1
     *   hour). Typically uses the same value as the flood_is_allowed() $window
     *   parameter. Expired events are purged on cron run to prevent the flood table
     *   from growing indefinitely.
     * @param $identifier
     *   Optional identifier (defaults to the current user's IP address).
     */
    function flood_register_event($name, $window = 3600, $identifier = NULL) {
      if (!isset($identifier)) {
        $identifier = ip_address();
      }
      db_insert('flood')
        ->fields(array(
          'event' => $name,
          'identifier' => $identifier,
          'timestamp' => REQUEST_TIME,
          'expiration' => REQUEST_TIME + $window,
        ))
        ->execute();
    }
    
    /**
     * Make the flood control mechanism forget about an event for the current visitor.
     *
     * @param $name
     *   The name of an event.
     * @param $identifier
     *   Optional identifier (defaults to the current user's IP address).
     */
    function flood_clear_event($name, $identifier = NULL) {
      if (!isset($identifier)) {
        $identifier = ip_address();
      }
      db_delete('flood')
        ->condition('event', $name)
        ->condition('identifier', $identifier)
        ->execute();
    }
    
    /**
     * Checks whether user is allowed to proceed with the specified event.
     *
     * Events can have thresholds saying that each user can only do that event
     * a certain number of times in a time window. This function verifies that the
     * current user has not exceeded this threshold.
     *
     * @param $name
     *   The unique name of the event.
     * @param $threshold
     *   The maximum number of times each user can do this event per time window.
     * @param $window
     *   Number of seconds in the time window for this event (default is 3600
     *   seconds, or 1 hour).
     * @param $identifier
     *   Unique identifier of the current user. Defaults to their IP address.
     *
     * @return
     *   TRUE if the user is allowed to proceed. FALSE if they have exceeded the
     *   threshold and should not be allowed to proceed.
     */
    function flood_is_allowed($name, $threshold, $window = 3600, $identifier = NULL) {
      if (!isset($identifier)) {
        $identifier = ip_address();
      }
      $number = db_query("SELECT COUNT(*) FROM {flood} WHERE event = :event AND identifier = :identifier AND timestamp > :timestamp", array(
        ':event' => $name,
        ':identifier' => $identifier,
        ':timestamp' => REQUEST_TIME - $window))
        ->fetchField();
      return ($number < $threshold);
    }
    
    /**
     * @defgroup sanitization Sanitization functions
     * @{
     * Functions to sanitize values.
     *
     * See http://drupal.org/writing-secure-code for information
     * on writing secure code.
     */
    
    /**
     * Strips dangerous protocols (e.g. 'javascript:') from a URI.
     *
     * This function must be called for all URIs within user-entered input prior
     * to being output to an HTML attribute value. It is often called as part of
     * check_url() or filter_xss(), but those functions return an HTML-encoded
     * string, so this function can be called independently when the output needs to
     * be a plain-text string for passing to t(), l(), drupal_attributes(), or
     * another function that will call check_plain() separately.
     *
     * @param $uri
     *   A plain-text URI that might contain dangerous protocols.
     *
     * @return
     *   A plain-text URI stripped of dangerous protocols. As with all plain-text
     *   strings, this return value must not be output to an HTML page without
     *   check_plain() being called on it. However, it can be passed to functions
     *   expecting plain-text strings.
     *
     * @see check_url()
     */
    function drupal_strip_dangerous_protocols($uri) {
      static $allowed_protocols;
    
      if (!isset($allowed_protocols)) {
        $allowed_protocols = array_flip(variable_get('filter_allowed_protocols', array('ftp', 'http', 'https', 'irc', 'mailto', 'news', 'nntp', 'rtsp', 'sftp', 'ssh', 'tel', 'telnet', 'webcal')));
      }
    
      // Iteratively remove any invalid protocol found.
      do {
        $before = $uri;
        $colonpos = strpos($uri, ':');
        if ($colonpos > 0) {
          // We found a colon, possibly a protocol. Verify.
          $protocol = substr($uri, 0, $colonpos);
          // If a colon is preceded by a slash, question mark or hash, it cannot
          // possibly be part of the URL scheme. This must be a relative URL, which
          // inherits the (safe) protocol of the base document.
          if (preg_match('![/?#]!', $protocol)) {
            break;
          }
          // Check if this is a disallowed protocol. Per RFC2616, section 3.2.3
          // (URI Comparison) scheme comparison must be case-insensitive.
          if (!isset($allowed_protocols[strtolower($protocol)])) {
            $uri = substr($uri, $colonpos + 1);
          }
        }
      } while ($before != $uri);
    
      return $uri;
    }
    
    /**
     * Strips dangerous protocols (e.g. 'javascript:') from a URI and encodes it for output to an HTML attribute value.
     *
     * @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
     *   value within a $attributes array passed to drupal_attributes(), because
     *   drupal_attributes() expects those values to be plain-text strings. To pass
     *   a filtered URI to drupal_attributes(), call
     *   drupal_strip_dangerous_protocols() instead.
     *
     * @see drupal_strip_dangerous_protocols()
     */
    function check_url($uri) {
      return check_plain(drupal_strip_dangerous_protocols($uri));
    }
    
    /**
     * Very permissive XSS/HTML filter for admin-only use.
     *
     * Use only for fields where it is impractical to use the
     * whole filter system, but where some (mainly inline) mark-up
     * is desired (so check_plain() is not acceptable).
     *
     * Allows all tags that can be used inside an HTML body, save
     * for scripts and styles.
     */
    function filter_xss_admin($string) {
      return filter_xss($string, array('a', 'abbr', 'acronym', 'address', 'b', 'bdo', 'big', 'blockquote', 'br', 'caption', 'cite', 'code', 'col', 'colgroup', 'dd', 'del', 'dfn', 'div', 'dl', 'dt', 'em', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', 'ins', 'kbd', 'li', 'ol', 'p', 'pre', 'q', 'samp', 'small', 'span', 'strong', 'sub', 'sup', 'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'tr', 'tt', 'ul', 'var'));
    }
    
    /**
     * Filters an HTML string to prevent cross-site-scripting (XSS) vulnerabilities.
     *
     * Based on kses by Ulf Harnhammar, see http://sourceforge.net/projects/kses.
     * For examples of various XSS attacks, see: http://ha.ckers.org/xss.html.
     *
     * This code does four things:
     * - Removes characters and constructs that can trick browsers.
     * - Makes sure all HTML entities are well-formed.
     * - Makes sure all HTML tags and attributes are well-formed.
     * - Makes sure no HTML tags contain URLs with a disallowed protocol (e.g.
     *   javascript:).
     *
     * @param $string
     *   The string with raw HTML in it. It will be stripped of everything that can
     *   cause an XSS attack.
     * @param $allowed_tags
     *   An array of allowed tags.
     *
     * @return
     *   An XSS safe version of $string, or an empty string if $string is not
     *   valid UTF-8.
     *
     * @see drupal_validate_utf8()
     * @ingroup sanitization
     */
    function filter_xss($string, $allowed_tags = array('a', 'em', 'strong', 'cite', 'blockquote', 'code', 'ul', 'ol', 'li', 'dl', 'dt', 'dd')) {
      // Only operate on valid UTF-8 strings. This is necessary to prevent cross
      // site scripting issues on Internet Explorer 6.
      if (!drupal_validate_utf8($string)) {
        return '';
      }
      // Store the text format
      _filter_xss_split($allowed_tags, TRUE);
      // Remove NULL characters (ignored by some browsers)
      $string = str_replace(chr(0), '', $string);
      // Remove Netscape 4 JS entities
      $string = preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string);
    
      // Defuse all HTML entities
      $string = str_replace('&', '&amp;', $string);
      // Change back only well-formed entities in our whitelist
      // Decimal numeric entities
      $string = preg_replace('/&amp;#([0-9]+;)/', '&#\1', $string);
      // Hexadecimal numeric entities
      $string = preg_replace('/&amp;#[Xx]0*((?:[0-9A-Fa-f]{2})+;)/', '&#x\1', $string);
      // Named entities
      $string = preg_replace('/&amp;([A-Za-z][A-Za-z0-9]*;)/', '&\1', $string);
    
      return preg_replace_callback('%
        (
        <(?=[^a-zA-Z!/])  # a lone <
        |                 # or
        <!--.*?-->        # a comment
        |                 # or
        <[^>]*(>|$)       # a string that starts with a <, up until the > or the end of the string
        |                 # or
        >                 # just a >
        )%x', '_filter_xss_split', $string);
    }
    
    /**
     * Processes an HTML tag.
     *
     * @param $m
     *   An array with various meaning depending on the value of $store.
     *   If $store is TRUE then the array contains the allowed tags.
     *   If $store is FALSE then the array has one element, the HTML tag to process.
     * @param $store
     *   Whether to store $m.
     * @return
     *   If the element isn't allowed, an empty string. Otherwise, the cleaned up
     *   version of the HTML element.
     */
    function _filter_xss_split($m, $store = FALSE) {
      static $allowed_html;
    
      if ($store) {
        $allowed_html = array_flip($m);
        return;
      }
    
      $string = $m[1];
    
      if (substr($string, 0, 1) != '<') {
        // We matched a lone ">" character
        return '&gt;';
      }
      elseif (strlen($string) == 1) {
        // We matched a lone "<" character
        return '&lt;';
      }
    
      if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?|(<!--.*?-->)$%', $string, $matches)) {
        // Seriously malformed
        return '';
      }
    
      $slash = trim($matches[1]);
      $elem = &$matches[2];
      $attrlist = &$matches[3];
      $comment = &$matches[4];
    
      if ($comment) {
        $elem = '!--';
      }
    
      if (!isset($allowed_html[strtolower($elem)])) {
        // Disallowed HTML element
        return '';
      }
    
      if ($comment) {
        return $comment;
      }
    
      if ($slash != '') {
        return "</$elem>";
      }
    
      // Is there a closing XHTML slash at the end of the attributes?
      $attrlist = preg_replace('%(\s?)/\s*$%', '\1', $attrlist, -1, $count);
      $xhtml_slash = $count ? ' /' : '';
    
      // Clean up attributes
      $attr2 = implode(' ', _filter_xss_attributes($attrlist));
      $attr2 = preg_replace('/[<>]/', '', $attr2);
      $attr2 = strlen($attr2) ? ' ' . $attr2 : '';
    
      return "<$elem$attr2$xhtml_slash>";
    }
    
    /**
     * Processes a string of HTML attributes.
     *
     * @return
     *   Cleaned up version of the HTML attributes.
     */
    function _filter_xss_attributes($attr) {
      $attrarr = array();
      $mode = 0;
      $attrname = '';
    
      while (strlen($attr) != 0) {
        // Was the last operation successful?
        $working = 0;
    
        switch ($mode) {
          case 0:
            // Attribute name, href for instance
            if (preg_match('/^([-a-zA-Z]+)/', $attr, $match)) {
              $attrname = strtolower($match[1]);
              $skip = ($attrname == 'style' || substr($attrname, 0, 2) == 'on');
              $working = $mode = 1;
              $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr);
            }
            break;
    
          case 1:
            // Equals sign or valueless ("selected")
            if (preg_match('/^\s*=\s*/', $attr)) {
              $working = 1; $mode = 2;
              $attr = preg_replace('/^\s*=\s*/', '', $attr);
              break;
            }
    
            if (preg_match('/^\s+/', $attr)) {
              $working = 1; $mode = 0;
              if (!$skip) {
                $attrarr[] = $attrname;
              }
              $attr = preg_replace('/^\s+/', '', $attr);
            }
            break;
    
          case 2:
            // Attribute value, a URL after href= for instance
            if (preg_match('/^"([^"]*)"(\s+|$)/', $attr, $match)) {
              $thisval = filter_xss_bad_protocol($match[1]);
    
              if (!$skip) {
                $attrarr[] = "$attrname=\"$thisval\"";
              }
              $working = 1;
              $mode = 0;
              $attr = preg_replace('/^"[^"]*"(\s+|$)/', '', $attr);
              break;
            }
    
            if (preg_match("/^'([^']*)'(\s+|$)/", $attr, $match)) {
              $thisval = filter_xss_bad_protocol($match[1]);
    
              if (!$skip) {
                $attrarr[] = "$attrname='$thisval'";
              }
              $working = 1; $mode = 0;
              $attr = preg_replace("/^'[^']*'(\s+|$)/", '', $attr);
              break;
            }
    
            if (preg_match("%^([^\s\"']+)(\s+|$)%", $attr, $match)) {
              $thisval = filter_xss_bad_protocol($match[1]);
    
              if (!$skip) {
                $attrarr[] = "$attrname=\"$thisval\"";
              }
              $working = 1; $mode = 0;
              $attr = preg_replace("%^[^\s\"']+(\s+|$)%", '', $attr);
            }
            break;
        }
    
        if ($working == 0) {
          // not well formed, remove and try again
          $attr = preg_replace('/
            ^
            (
            "[^"]*("|$)     # - a string that starts with a double quote, up until the next double quote or the end of the string
            |               # or
            \'[^\']*(\'|$)| # - a string that starts with a quote, up until the next quote or the end of the string
            |               # or
            \S              # - a non-whitespace character
            )*              # any number of the above three
            \s*             # any number of whitespaces
            /x', '', $attr);
          $mode = 0;
        }
      }
    
      // The attribute list ends with a valueless attribute like "selected".
      if ($mode == 1 && !$skip) {
        $attrarr[] = $attrname;
      }
      return $attrarr;
    }
    
    /**
     * Processes an HTML attribute value and ensures it does not contain an URL with a disallowed protocol (e.g. javascript:).
     *
     * @param $string
     *   The string with the attribute value.
     * @param $decode
     *   (Deprecated) Whether to decode entities in the $string. Set to FALSE if the
     *   $string is in plain text, TRUE otherwise. Defaults to TRUE. This parameter
     *   is deprecated and will be removed in Drupal 8. To process a plain-text URI,
     *   call drupal_strip_dangerous_protocols() or check_url() instead.
     * @return
     *   Cleaned up and HTML-escaped version of $string.
     */
    function filter_xss_bad_protocol($string, $decode = TRUE) {
      // Get the plain text representation of the attribute value (i.e. its meaning).
      // @todo Remove the $decode parameter in Drupal 8, and always assume an HTML
      //   string that needs decoding.
      if ($decode) {
        if (!function_exists('decode_entities')) {
          require_once DRUPAL_ROOT . '/includes/unicode.inc';
        }
    
        $string = decode_entities($string);
      }
      return check_plain(drupal_strip_dangerous_protocols($string));
    }
    
    /**
     * @} End of "defgroup sanitization".
     */
    
    /**
     * @defgroup format Formatting
     * @{
     * Functions to format numbers, strings, dates, etc.
     */
    
    /**
     * Formats an RSS channel.
     *
     * Arbitrary elements may be added using the $args associative array.
     */
    function format_rss_channel($title, $link, $description, $items, $langcode = NULL, $args = array()) {
      global $language_content;
      $langcode = $langcode ? $langcode : $language_content->language;
    
      $output = "<channel>\n";
      $output .= ' <title>' . check_plain($title) . "</title>\n";
      $output .= ' <link>' . check_url($link) . "</link>\n";
    
      // The RSS 2.0 "spec" doesn't indicate HTML can be used in the description.
      // We strip all HTML tags, but need to prevent double encoding from properly
      // escaped source data (such as &amp becoming &amp;amp;).
      $output .= ' <description>' . check_plain(decode_entities(strip_tags($description))) . "</description>\n";
      $output .= ' <language>' . check_plain($langcode) . "</language>\n";
      $output .= format_xml_elements($args);
      $output .= $items;
      $output .= "</channel>\n";
    
      return $output;
    }
    
    /**
     * Format a single RSS item.
     *
     * Arbitrary elements may be added using the $args associative array.
     */
    function format_rss_item($title, $link, $description, $args = array()) {
      $output = "<item>\n";
      $output .= ' <title>' . check_plain($title) . "</title>\n";
      $output .= ' <link>' . check_url($link) . "</link>\n";
      $output .= ' <description>' . check_plain($description) . "</description>\n";
      $output .= format_xml_elements($args);
      $output .= "</item>\n";
    
      return $output;
    }
    
    /**
     * Format XML elements.
     *
     * @param $array
     *   An array where each item represents an element and is either a:
     *   - (key => value) pair (<key>value</key>)
     *   - Associative array with fields:
     *     - 'key': element name
     *     - '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) {
      $output = '';
      foreach ($array as $key => $value) {
        if (is_numeric($key)) {
          if ($value['key']) {
            $output .= ' <' . $value['key'];
            if (isset($value['attributes']) && is_array($value['attributes'])) {
              $output .= drupal_attributes($value['attributes']);
            }
    
            if (isset($value['value']) && $value['value'] != '') {
              $output .= '>' . (is_array($value['value']) ? format_xml_elements($value['value']) : check_plain($value['value'])) . '</' . $value['key'] . ">\n";
            }
            else {
              $output .= " />\n";
            }
          }
        }
        else {
          $output .= ' <' . $key . '>' . (is_array($value) ? format_xml_elements($value) : check_plain($value)) . "</$key>\n";
        }
      }
      return $output;
    }
    
    /**
     * Format a string containing a count of items.
     *
     * This function ensures that the string is pluralized correctly. Since t() is
     * called by this function, make sure not to pass already-localized strings to
     * it.
     *
     * For example:
     * @code
     *   $output = format_plural($node->comment_count, '1 comment', '@count comments');
     * @endcode
     *
     * Example with additional replacements:
     * @code
     *   $output = format_plural($update_count,
     *     'Changed the content type of 1 post from %old-type to %new-type.',
     *     'Changed the content type of @count posts from %old-type to %new-type.',
     *     array('%old-type' => $info->old_type, '%new-type' => $info->new_type)));
     * @endcode
     *
     * @param $count
     *   The item count to display.
     * @param $singular
     *   The string for the singular case. Please make sure it is clear this is
     *   singular, to ease translation (e.g. use "1 new comment" instead of "1 new").
     *   Do not use @count in the singular string.
     * @param $plural
     *   The string for the plural case. Please make sure it is clear this is plural,
     *   to ease translation. Use @count in place of the item count, as in "@count
     *   new comments".
     * @param $args
     *   An associative array of replacements to make after translation. Incidences
     *   of any key in this array are replaced with the corresponding value.
     *   Based on the first character of the key, the value is escaped and/or themed:
     *    - !variable: inserted as is
     *    - @variable: escape plain text to HTML (check_plain)
     *    - %variable: escape text and theme as a placeholder for user-submitted
     *      content (check_plain + drupal_placeholder)
     *   Note that you do not need to include @count in this array.
     *   This replacement is done automatically for the plural case.
     * @param $options
     *   An associative array of additional options, with the following keys:
     *     - 'langcode' (default to the current language) The language code to
     *       translate to a language other than what is used to display the page.
     *     - 'context' (default to the empty context) The context the source string
     *       belongs to.
     * @return
     *   A translated string.
     */
    function format_plural($count, $singular, $plural, array $args = array(), array $options = array()) {
      $args['@count'] = $count;
      if ($count == 1) {
        return t($singular, $args, $options);
      }
    
      // Get the plural index through the gettext formula.
      $index = (function_exists('locale_get_plural')) ? locale_get_plural($count, isset($options['langcode']) ? $options['langcode'] : NULL) : -1;
      // Backwards compatibility.
      if ($index < 0) {
        return t($plural, $args, $options);
      }
      else {
        switch ($index) {
          case "0":
            return t($singular, $args, $options);
          case "1":
            return t($plural, $args, $options);
          default:
            unset($args['@count']);
            $args['@count[' . $index . ']'] = $count;
            return t(strtr($plural, array('@count' => '@count[' . $index . ']')), $args, $options);
        }
      }
    }
    
    /**
     * Parse a given byte count.
     *
     * @param $size
     *   A size expressed as a number of bytes with optional SI or IEC binary unit
     *   prefix (e.g. 2, 3K, 5MB, 10G, 6GiB, 8 bytes, 9mbytes).
     * @return
     *   An integer representation of the size in bytes.
     */
    function parse_size($size) {
      $unit = preg_replace('/[^bkmgtpezy]/i', '', $size); // Remove the non-unit characters from the size.
      $size = preg_replace('/[^0-9\.]/', '', $size); // Remove the non-numeric characters from the size.
      if ($unit) {
        // Find the position of the unit in the ordered string which is the power of magnitude to multiply a kilobyte by.
        return round($size * pow(DRUPAL_KILOBYTE, stripos('bkmgtpezy', $unit[0])));
      }
      else {
        return round($size);
      }
    }
    
    /**
     * Generate a string representation for the given byte count.
     *
     * @param $size
     *   A size in bytes.
     * @param $langcode
     *   Optional language code to translate to a language other than what is used
     *   to display the page.
     * @return
     *   A translated string representation of the size.
     */
    function format_size($size, $langcode = NULL) {
      if ($size < DRUPAL_KILOBYTE) {
        return format_plural($size, '1 byte', '@count bytes', array(), array('langcode' => $langcode));
      }
      else {
        $size = $size / DRUPAL_KILOBYTE; // Convert bytes to kilobytes.
        $units = array(
          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' => $langcode)),
        );
        foreach ($units as $unit) {
          if (round($size, 2) >= DRUPAL_KILOBYTE) {
            $size = $size / DRUPAL_KILOBYTE;
          }
          else {
            break;
          }
        }
        return str_replace('@size', round($size, 2), $unit);
      }
    }
    
    /**
     * Format a time interval with the requested granularity.
     *
     * @param $timestamp
     *   The length of the interval in seconds.
     * @param $granularity
     *   How many different units to display in the string.
     * @param $langcode
     *   Optional language code to translate to a language other than
     *   what is used to display the page.
     * @return
     *   A translated string representation of the interval.
     */
    function format_interval($timestamp, $granularity = 2, $langcode = NULL) {
      $units = array(
        '1 year|@count years' => 31536000,
        '1 month|@count months' => 2592000,
        '1 week|@count weeks' => 604800,
        '1 day|@count days' => 86400,
        '1 hour|@count hours' => 3600,
        '1 min|@count min' => 60,
        '1 sec|@count sec' => 1
      );
      $output = '';
      foreach ($units as $key => $value) {
        $key = explode('|', $key);
        if ($timestamp >= $value) {
          $output .= ($output ? ' ' : '') . format_plural(floor($timestamp / $value), $key[0], $key[1], array(), array('langcode' => $langcode));
          $timestamp %= $value;
          $granularity--;
        }
    
        if ($granularity == 0) {
          break;
        }
      }
      return $output ? $output : t('0 sec', array(), array('langcode' => $langcode));
    }
    
    /**
     * Formats a date, using a date type or a custom date format string.
     *
     * @param $timestamp
     *   A UNIX timestamp to format.
     * @param $type
     *   (optional) The format to use, one of:
     *   - 'short', 'medium', or 'long' (the corresponding built-in date formats).
     *   - The name of a date type defined by a module in hook_date_format_types(),
     *     if it's been assigned a format.
     *   - The machine name of an administrator-defined date format.
     *   - 'custom', to use $format.
     *   Defaults to 'medium'.
     * @param $format
     *   (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.
     * @param $timezone
     *   (optional) Time zone identifier, as described at
     *   http://php.net/manual/en/timezones.php Defaults to the time zone used to
     *   display the page.
     * @param $langcode
     *   (optional) Language code to translate to. Defaults to the language used to
     *   display the page.
     *
     * @return
     *   A translated date string in the requested format.
     */
    function format_date($timestamp, $type = 'medium', $format = '', $timezone = NULL, $langcode = NULL) {
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['timezones'] = &drupal_static(__FUNCTION__);
      }
      $timezones = &$drupal_static_fast['timezones'];
    
      if (!isset($timezone)) {
        $timezone = date_default_timezone_get();
      }
      // Store DateTimeZone objects in an array rather than repeatedly
      // constructing identical objects over the life of a request.
      if (!isset($timezones[$timezone])) {
        $timezones[$timezone] = timezone_open($timezone);
      }
    
      // Use the default langcode if none is set.
      global $language;
      if (empty($langcode)) {
        $langcode = isset($language->language) ? $language->language : 'en';
      }
    
      switch ($type) {
        case 'short':
          $format = variable_get('date_format_short', 'm/d/Y - H:i');
          break;
    
        case 'long':
          $format = variable_get('date_format_long', 'l, F j, Y - H:i');
          break;
    
        case 'custom':
          // No change to format.
          break;
    
        case 'medium':
        default:
          // Retrieve the format of the custom $type passed.
          if ($type != 'medium') {
            $format = variable_get('date_format_' . $type, '');
          }
          // Fall back to 'medium'.
          if ($format === '') {
            $format = variable_get('date_format_medium', 'D, m/d/Y - H:i');
          }
          break;
      }
    
      // Create a DateTime object from the timestamp.
      $date_time = date_create('@' . $timestamp);
      // Set the time zone for the DateTime object.
      date_timezone_set($date_time, $timezones[$timezone]);
    
      // Encode markers that should be translated. 'A' becomes '\xEF\AA\xFF'.
      // xEF and xFF are invalid UTF-8 sequences, and we assume they are not in the
      // input string.
      // Paired backslashes are isolated to prevent errors in read-ahead evaluation.
      // The read-ahead expression ensures that A matches, but not \A.
      $format = preg_replace(array('/\\\\\\\\/', '/(?<!\\\\)([AaeDlMTF])/'), array("\xEF\\\\\\\\\xFF", "\xEF\\\\\$1\$1\xFF"), $format);
    
      // Call date_format().
      $format = date_format($date_time, $format);
    
      // Pass the langcode to _format_date_callback().
      _format_date_callback(NULL, $langcode);
    
      // Translate the marked sequences.
      return preg_replace_callback('/\xEF([AaeDlMTF]?)(.*?)\xFF/', '_format_date_callback', $format);
    }
    
    /**
     * Returns an ISO8601 formatted date based on the given date.
     *
     * Can be used as a callback for RDF mappings.
     *
     * @param $date
     *   A UNIX timestamp.
     * @return string
     *   An ISO8601 formatted date.
     */
    function date_iso8601($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);
    }
    
    /**
     * Callback function for preg_replace_callback().
     */
    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';
        }
    
        if ($code == '') {
          $cache[$langcode][$code][$string] = $string;
        }
        else {
          $cache[$langcode][$code][$string] = t($string, array(), $options);
        }
      }
      return $cache[$langcode][$code][$string];
    }
    
    /**
     * Format a username.
     *
     * By default, the passed-in object's 'name' property is used if it exists, or
     * else, the site-defined value for the 'anonymous' variable. However, a module
     * may override this by implementing hook_username_alter(&$name, $account).
     *
     * @see hook_username_alter()
     *
     * @param $account
     *   The account object for the user whose name is to be formatted.
     *
     * @return
     *   An unsanitized string with the username to display. The code receiving
     *   this result must ensure that check_plain() is called on it before it is
     *   printed to the page.
     */
    function format_username($account) {
      $name = !empty($account->name) ? $account->name : variable_get('anonymous', t('Anonymous'));
      drupal_alter('username', $name, $account);
      return $name;
    }
    
    /**
     * @} End of "defgroup format".
     */
    
    /**
     * Generates an internal or external URL.
     *
     * When creating links in modules, consider whether l() could be a better
     * alternative than url().
     *
     * @param $path
     *   The internal path or external URL being linked to, such as "node/34" or
     *   "http://example.com/foo". A few notes:
     *   - If you provide a full URL, it will be considered an external URL.
     *   - If you provide only the path (e.g. "node/34"), it will be
     *     considered an internal link. In this case, it should be a system URL,
     *     and it will be replaced with the alias, if one exists. Additional query
     *     arguments for internal paths must be supplied in $options['query'], not
     *     included in $path.
     *   - If you provide an internal path and $options['alias'] is set to TRUE, the
     *     path is assumed already to be the correct path alias, and the alias is
     *     not looked up.
     *   - The special string '<front>' generates a link to the site's base URL.
     *   - If your external URL contains a query (e.g. http://example.com/foo?a=b),
     *     then you can either URL encode the query keys and values yourself and
     *     include them in $path, or use $options['query'] to let this function
     *     URL encode them.
     * @param $options
     *   An associative array of additional options, with the following elements:
     *   - 'query': An array of query key/value-pairs (without any URL-encoding) to
     *     append to the URL.
     *   - 'fragment': A fragment identifier (named anchor) to append to the URL.
     *     Do not include the leading '#' character.
     *   - 'absolute': Defaults to FALSE. Whether to force the output to be an
     *     absolute link (beginning with http:). Useful for links that will be
     *     displayed outside the site, such as in an RSS feed.
     *   - 'alias': Defaults to FALSE. Whether the given path is a URL alias
     *     already.
     *   - 'external': Whether the given path is an external URL.
     *   - 'language': An optional language object. If the path being linked to is
     *     internal to the site, $options['language'] is used to look up the alias
     *     for the URL. If $options['language'] is omitted, the global $language_url
     *     will be used.
     *   - 'https': Whether this URL should point to a secure location. If not
     *     defined, the current scheme is used, so the user stays on http or https
     *     respectively. TRUE enforces HTTPS and FALSE enforces HTTP, but HTTPS can
     *     only be enforced when the variable 'https' is set to TRUE.
     *   - 'base_url': Only used internally, to modify the base URL when a language
     *     dependent URL requires so.
     *   - 'prefix': Only used internally, to modify the path when a language
     *     dependent URL requires so.
     *   - 'script': The script filename in Drupal's root directory to use when
     *     clean URLs are disabled, such as 'index.php'. Defaults to an empty
     *     string, as most modern web servers automatically find 'index.php'. If
     *     clean URLs are disabled, the value of $path is appended as query
     *     parameter 'q' to $options['script'] in the returned URL. When deploying
     *     Drupal on a web server that cannot be configured to automatically find
     *     index.php, then hook_url_outbound_alter() can be implemented to force
     *     this value to 'index.php'.
     *   - 'entity_type': The entity type of the object that called url(). Only set if
     *     url() is invoked by entity_uri().
     *   - 'entity': The entity object (such as a node) for which the URL is being
     *     generated. Only set if url() is invoked by entity_uri().
     *
     * @return
     *   A string containing a URL to the given path.
     */
    function url($path = NULL, array $options = array()) {
      // Merge in defaults.
      $options += array(
        'fragment' => '',
        'query' => array(),
        'absolute' => FALSE,
        'alias' => FALSE,
        'prefix' => ''
      );
    
      if (!isset($options['external'])) {
        // Return an external link if $path contains an allowed absolute URL. Only
        // call the slow drupal_strip_dangerous_protocols() if $path contains a ':'
        // before any / ? or #. Note: we could use url_is_external($path) here, but
        // that would require another function call, and performance inside url() is
        // critical.
        $colonpos = strpos($path, ':');
        $options['external'] = ($colonpos !== FALSE && !preg_match('![/?#]!', substr($path, 0, $colonpos)) && drupal_strip_dangerous_protocols($path) == $path);
      }
    
      // Preserve the original path before altering or aliasing.
      $original_path = $path;
    
      // Allow other modules to alter the outbound URL and options.
      drupal_alter('url_outbound', $path, $options, $original_path);
    
      if (isset($options['fragment']) && $options['fragment'] !== '') {
        $options['fragment'] = '#' . $options['fragment'];
      }
    
      if ($options['external']) {
        // Split off the fragment.
        if (strpos($path, '#') !== FALSE) {
          list($path, $old_fragment) = explode('#', $path, 2);
          // If $options contains no fragment, take it over from the path.
          if (isset($old_fragment) && !$options['fragment']) {
            $options['fragment'] = '#' . $old_fragment;
          }
        }
        // Append the query.
        if ($options['query']) {
          $path .= (strpos($path, '?') !== FALSE ? '&' : '?') . drupal_http_build_query($options['query']);
        }
        if (isset($options['https']) && variable_get('https', FALSE)) {
          if ($options['https'] === TRUE) {
            $path = str_replace('http://', 'https://', $path);
          }
          elseif ($options['https'] === FALSE) {
            $path = str_replace('https://', 'http://', $path);
          }
        }
        // Reassemble.
        return $path . $options['fragment'];
      }
    
      global $base_url, $base_secure_url, $base_insecure_url;
    
      // The base_url might be rewritten from the language rewrite in domain mode.
      if (!isset($options['base_url'])) {
        if (isset($options['https']) && variable_get('https', FALSE)) {
          if ($options['https'] === TRUE) {
            $options['base_url'] = $base_secure_url;
            $options['absolute'] = TRUE;
          }
          elseif ($options['https'] === FALSE) {
            $options['base_url'] = $base_insecure_url;
            $options['absolute'] = TRUE;
          }
        }
        else {
          $options['base_url'] = $base_url;
        }
      }
    
      // The special path '<front>' links to the default front page.
      if ($path == '<front>') {
        $path = '';
      }
      elseif (!empty($path) && !$options['alias']) {
        $language = isset($options['language']) && isset($options['language']->language) ? $options['language']->language : '';
        $alias = drupal_get_path_alias($original_path, $language);
        if ($alias != $original_path) {
          $path = $alias;
        }
      }
    
      $base = $options['absolute'] ? $options['base_url'] . '/' : base_path();
      $prefix = empty($path) ? rtrim($options['prefix'], '/') : $options['prefix'];
    
      // With Clean URLs.
      if (!empty($GLOBALS['conf']['clean_url'])) {
        $path = drupal_encode_path($prefix . $path);
        if ($options['query']) {
          return $base . $path . '?' . drupal_http_build_query($options['query']) . $options['fragment'];
        }
        else {
          return $base . $path . $options['fragment'];
        }
      }
      // Without Clean URLs.
      else {
        $path = $prefix . $path;
        $query = array();
        if (!empty($path)) {
          $query['q'] = $path;
        }
        if ($options['query']) {
          // We do not use array_merge() here to prevent overriding $path via query
          // parameters.
          $query += $options['query'];
        }
        $query = $query ? ('?' . drupal_http_build_query($query)) : '';
        $script = isset($options['script']) ? $options['script'] : '';
        return $base . $script . $query . $options['fragment'];
      }
    }
    
    /**
     * Return TRUE if a path is external to Drupal (e.g. http://example.com).
     *
     * If a path cannot be assessed by Drupal's menu handler, then we must
     * treat it as potentially insecure.
     *
     * @param $path
     *   The internal path or external URL being linked to, such as "node/34" or
     *   "http://example.com/foo".
     * @return
     *   Boolean TRUE or FALSE, where TRUE indicates an external path.
     */
    function url_is_external($path) {
      $colonpos = strpos($path, ':');
      // Only call the slow drupal_strip_dangerous_protocols() if $path contains a
      // ':' before any / ? or #.
      return $colonpos !== FALSE && !preg_match('![/?#]!', substr($path, 0, $colonpos)) && drupal_strip_dangerous_protocols($path) == $path;
    }
    
    /**
     * Format an attribute string for a HTTP header.
     *
     * @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.
     *
     * @see drupal_add_http_header()
     */
    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) : '';
    }
    
    /**
     * Converts an associative array to an attribute string for use in XML/HTML tags.
     *
     * Each array key and its value will be formatted into an attribute string.
     * If a value is itself an array, then its elements are concatenated to a single
     * space-delimited string (for example, a class attribute with multiple values).
     *
     * Attribute values are sanitized by running them through check_plain().
     * Attribute names are not automatically sanitized. When using user-supplied
     * attribute names, it is strongly recommended to allow only white-listed names,
     * since certain attributes carry security risks and can be abused.
     *
     * Examples of security aspects when using drupal_attributes:
     * @code
     *   // By running the value in the following statement through check_plain,
     *   // the malicious script is neutralized.
     *   drupal_attributes(array('title' => t('<script>steal_cookie();</script>')));
     *
     *   // The statement below demonstrates dangerous use of drupal_attributes, and
     *   // will return an onmouseout attribute with JavaScript code that, when used
     *   // as attribute in a tag, will cause users to be redirected to another site.
     *   //
     *   // In this case, the 'onmouseout' attribute should not be whitelisted --
     *   // you don't want users to have the ability to add this attribute or others
     *   // that take JavaScript commands.
     *   drupal_attributes(array('onmouseout' => 'window.location="http://malicious.com/";')));
     * @endcode
     *
     * @param $attributes
     *   An associative array of key-value pairs to be converted to attributes.
     *
     * @return
     *   A string ready for insertion in a tag (starts with a space).
     *
     * @ingroup sanitization
     */
    function drupal_attributes(array $attributes = array()) {
      foreach ($attributes as $attribute => &$data) {
        $data = implode(' ', (array) $data);
        $data = $attribute . '="' . check_plain($data) . '"';
      }
      return $attributes ? ' ' . implode(' ', $attributes) : '';
    }
    
    /**
     * Formats an internal or external URL link as an HTML anchor tag.
     *
     * This function correctly handles aliased paths, and adds an 'active' class
     * 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.
     *
     * @param $text
     *   The link text for the anchor tag.
     * @param $path
     *   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
     *   check_plain() before it is inserted into the HTML anchor tag, to ensure
     *   well-formed HTML. See url() for more information and notes.
     * @param array $options
     *   An associative array of additional options, with the following elements:
     *   - 'attributes': An associative array of HTML attributes to apply to the
     *     anchor tag. If element 'class' is included, it must be an array; 'title'
     *     must be a string; other elements are more flexible, as they just need
     *     to work in a call to drupal_attributes($options['attributes']).
     *   - '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.
     *   - '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().
     *   - Additional $options elements used by the url() function.
     *
     * @return
     *   An HTML string containing a link to the given path.
     */
    function l($text, $path, array $options = array()) {
      global $language_url;
      static $use_theme = NULL;
    
      // Merge in defaults.
      $options += array(
        'attributes' => array(),
        'html' => FALSE,
      );
    
      // Append active class.
      if (($path == $_GET['q'] || ($path == '<front>' && drupal_is_front_page())) &&
          (empty($options['language']) || $options['language']->language == $language_url->language)) {
        $options['attributes']['class'][] = 'active';
      }
    
      // Remove all HTML and PHP tags from a tooltip. For best performance, we act only
      // if a quick strpos() pre-check gave a suspicion (because strip_tags() is expensive).
      if (isset($options['attributes']['title']) && strpos($options['attributes']['title'], '<') !== FALSE) {
        $options['attributes']['title'] = strip_tags($options['attributes']['title']);
      }
    
      // Determine if rendering of the link is to be done with a theme function
      // or the inline default. Inline is faster, but if the theme system has been
      // loaded and a module or theme implements a preprocess or process function
      // or overrides the theme_link() function, then invoke theme(). Preliminary
      // benchmarks indicate that invoking theme() can slow down the l() function
      // by 20% or more, and that some of the link-heavy Drupal pages spend more
      // than 10% of the total page request time in the l() function.
      if (!isset($use_theme) && function_exists('theme')) {
        // Allow edge cases to prevent theme initialization and force inline link
        // rendering.
        if (variable_get('theme_link', TRUE)) {
          drupal_theme_initialize();
          $registry = theme_get_registry();
          // We don't want to duplicate functionality that's in theme(), so any
          // hint of a module or theme doing anything at all special with the 'link'
          // theme hook should simply result in theme() being called. This includes
          // the overriding of theme_link() with an alternate function or template,
          // the presence of preprocess or process functions, or the presence of
          // include files.
          $use_theme = !isset($registry['link']['function']) || ($registry['link']['function'] != 'theme_link');
          $use_theme = $use_theme || !empty($registry['link']['preprocess functions']) || !empty($registry['link']['process functions']) || !empty($registry['link']['includes']);
        }
        else {
          $use_theme = FALSE;
        }
      }
      if ($use_theme) {
        return theme('link', array('text' => $text, 'path' => $path, 'options' => $options));
      }
      // The result of url() is a plain-text URL. Because we are using it here
      // in an HTML argument context, we need to encode it properly.
      return '<a href="' . check_plain(url($path, $options)) . '"' . drupal_attributes($options['attributes']) . '>' . ($options['html'] ? $text : check_plain($text)) . '</a>';
    }
    
    /**
     * Delivers a page callback result to the browser in the appropriate format.
     *
     * This function is most commonly called by menu_execute_active_handler(), but
     * can also be called by error conditions such as drupal_not_found(),
     * drupal_access_denied(), and drupal_site_offline().
     *
     * When a user requests a page, index.php calls menu_execute_active_handler(),
     * which calls the 'page callback' function registered in hook_menu(). The page
     * callback function can return one of:
     * - NULL: to indicate no content.
     * - An integer menu status constant: to indicate an error condition.
     * - A string of HTML content.
     * - A renderable array of content.
     * Returning a renderable array rather than a string of HTML is preferred,
     * because that provides modules with more flexibility in customizing the final
     * result.
     *
     * When the page callback returns its constructed content to
     * menu_execute_active_handler(), this function gets called. The purpose of
     * this function is to determine the most appropriate 'delivery callback'
     * function to route the content to. The delivery callback function then
     * sends the content to the browser in the needed format. The default delivery
     * callback is drupal_deliver_html_page(), which delivers the content as an HTML
     * page, complete with blocks in addition to the content. This default can be
     * overridden on a per menu router item basis by setting 'delivery callback' in
     * hook_menu() or hook_menu_alter(), and can also be overridden on a per request
     * basis in hook_page_delivery_callback_alter().
     *
     * For example, the same page callback function can be used for an HTML
     * version of the page and an Ajax version of the page. The page callback
     * function just needs to decide what content is to be returned and the
     * delivery callback function will send it as an HTML page or an Ajax
     * response, as appropriate.
     *
     * In order for page callbacks to be reusable in different delivery formats,
     * they should not issue any "print" or "echo" statements, but instead just
     * return content.
     *
     * Also note that this function does not perform access checks. The delivery
     * callback function specified in hook_menu(), hook_menu_alter(), or
     * hook_page_delivery_callback_alter() will be called even if the router item
     * access checks fail. This is intentional (it is needed for JSON and other
     * purposes), but it has security implications. Do not call this function
     * directly unless you understand the security implications, and be careful in
     * writing delivery callbacks, so that they do not violate security. See
     * drupal_deliver_html_page() for an example of a delivery callback that
     * respects security.
     *
     * @param $page_callback_result
     *   The result of a page callback. Can be one of:
     *   - NULL: to indicate no content.
     *   - An integer menu status constant: to indicate an error condition.
     *   - A string of HTML content.
     *   - A renderable array of content.
     * @param $default_delivery_callback
     *   (Optional) If given, it is the name of a delivery function most likely
     *   to be appropriate for the page request as determined by the calling
     *   function (e.g., menu_execute_active_handler()). If not given, it is
     *   determined from the menu router information of the current page.
     *
     * @see menu_execute_active_handler()
     * @see hook_menu()
     * @see hook_menu_alter()
     * @see hook_page_delivery_callback_alter()
     */
    function drupal_deliver_page($page_callback_result, $default_delivery_callback = NULL) {
      if (!isset($default_delivery_callback) && ($router_item = menu_get_item())) {
        $default_delivery_callback = $router_item['delivery_callback'];
      }
      $delivery_callback = !empty($default_delivery_callback) ? $default_delivery_callback : 'drupal_deliver_html_page';
      // Give modules a chance to alter the delivery callback used, based on
      // request-time context (e.g., HTTP request headers).
      drupal_alter('page_delivery_callback', $delivery_callback);
      if (function_exists($delivery_callback)) {
        $delivery_callback($page_callback_result);
      }
      else {
        // If a delivery callback is specified, but doesn't exist as a function,
        // something is wrong, but don't print anything, since it's not known
        // what format the response needs to be in.
        watchdog('delivery callback not found', 'callback %callback not found: %q.', array('%callback' => $delivery_callback, '%q' => $_GET['q']), WATCHDOG_ERROR);
      }
    }
    
    /**
     * Package and send the result of a page callback to the browser as HTML.
     *
     * @param $page_callback_result
     *   The result of a page callback. Can be one of:
     *   - NULL: to indicate no content.
     *   - An integer menu status constant: to indicate an error condition.
     *   - A string of HTML content.
     *   - A renderable array of content.
     *
     * @see drupal_deliver_page()
     */
    function drupal_deliver_html_page($page_callback_result) {
      // Emit the correct charset HTTP header, but not if the page callback
      // result is NULL, since that likely indicates that it printed something
      // in which case, no further headers may be sent, and not if code running
      // for this page request has already set the content type header.
      if (isset($page_callback_result) && is_null(drupal_get_http_header('Content-Type'))) {
        drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
      }
    
      // Menu status constants are integers; page content is a string or array.
      if (is_int($page_callback_result)) {
        // @todo: Break these up into separate functions?
        switch ($page_callback_result) {
          case MENU_NOT_FOUND:
            // Print a 404 page.
            drupal_add_http_header('Status', '404 Not Found');
    
            watchdog('page not found', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
    
            // Keep old path for reference, and to allow forms to redirect to it.
            if (!isset($_GET['destination'])) {
              $_GET['destination'] = $_GET['q'];
            }
    
            $path = drupal_get_normal_path(variable_get('site_404', ''));
            if ($path && $path != $_GET['q']) {
              // Custom 404 handler. Set the active item in case there are tabs to
              // display, or other dependencies on the path.
              menu_set_active_item($path);
              $return = menu_execute_active_handler($path, FALSE);
            }
    
            if (empty($return) || $return == MENU_NOT_FOUND || $return == MENU_ACCESS_DENIED) {
              // Standard 404 handler.
              drupal_set_title(t('Page not found'));
              $return = t('The requested page could not be found.');
            }
    
            drupal_set_page_content($return);
            $page = element_info('page');
            print drupal_render_page($page);
            break;
    
          case MENU_ACCESS_DENIED:
            // Print a 403 page.
            drupal_add_http_header('Status', '403 Forbidden');
            watchdog('access denied', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
    
            // Keep old path for reference, and to allow forms to redirect to it.
            if (!isset($_GET['destination'])) {
              $_GET['destination'] = $_GET['q'];
            }
    
            $path = drupal_get_normal_path(variable_get('site_403', ''));
            if ($path && $path != $_GET['q']) {
              // Custom 403 handler. Set the active item in case there are tabs to
              // display or other dependencies on the path.
              menu_set_active_item($path);
              $return = menu_execute_active_handler($path, FALSE);
            }
    
            if (empty($return) || $return == MENU_NOT_FOUND || $return == MENU_ACCESS_DENIED) {
              // Standard 403 handler.
              drupal_set_title(t('Access denied'));
              $return = t('You are not authorized to access this page.');
            }
    
            print drupal_render_page($return);
            break;
    
          case MENU_SITE_OFFLINE:
            // Print a 503 page.
            drupal_maintenance_theme();
            drupal_add_http_header('Status', '503 Service unavailable');
            drupal_set_title(t('Site under maintenance'));
            print theme('maintenance_page', array('content' => filter_xss_admin(variable_get('maintenance_mode_message',
              t('@site is currently under maintenance. We should be back shortly. Thank you for your patience.', array('@site' => variable_get('site_name', 'Drupal')))))));
            break;
        }
      }
      elseif (isset($page_callback_result)) {
        // Print anything besides a menu constant, assuming it's not NULL or
        // undefined.
        print drupal_render_page($page_callback_result);
      }
    
      // Perform end-of-request tasks.
      drupal_page_footer();
    }
    
    /**
     * Perform end-of-request tasks.
     *
     * This function sets the page cache if appropriate, and allows modules to
     * react to the closing of the page by calling hook_exit().
     */
    function drupal_page_footer() {
      global $user;
    
      module_invoke_all('exit');
    
      // Commit the user session, if needed.
      drupal_session_commit();
    
      if (variable_get('cache', 0) && ($cache = drupal_page_set_cache())) {
        drupal_serve_page_from_cache($cache);
      }
      else {
        ob_flush();
      }
    
      _registry_check_code(REGISTRY_WRITE_LOOKUP_CACHE);
      drupal_cache_system_paths();
      module_implements_write_cache();
      system_run_automated_cron();
    }
    
    /**
     * Perform end-of-request tasks.
     *
     * In some cases page requests need to end without calling drupal_page_footer().
     * In these cases, call drupal_exit() instead. There should rarely be a reason
     * to call exit instead of drupal_exit();
     *
     * @param $destination
     *   If this function is called from drupal_goto(), then this argument
     *   will be a fully-qualified URL that is the destination of the redirect.
     *   This should be passed along to hook_exit() implementations.
     */
    function drupal_exit($destination = NULL) {
      if (drupal_get_bootstrap_phase() == DRUPAL_BOOTSTRAP_FULL) {
        if (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update') {
          module_invoke_all('exit', $destination);
        }
        drupal_session_commit();
      }
      exit;
    }
    
    /**
     * Form an associative array from a linear array.
     *
     * This function walks through the provided array and constructs an associative
     * array out of it. The keys of the resulting array will be the values of the
     * input array. The values will be the same as the keys unless a function is
     * specified, in which case the output of the function is used for the values
     * instead.
     *
     * @param $array
     *   A linear array.
     * @param $function
     *   A name of a function to apply to all values before output.
     *
     * @return
     *   An associative array.
     */
    function drupal_map_assoc($array, $function = NULL) {
      // array_combine() fails with empty arrays:
      // http://bugs.php.net/bug.php?id=34857.
      $array = !empty($array) ? array_combine($array, $array) : array();
      if (is_callable($function)) {
        $array = array_map($function, $array);
      }
      return $array;
    }
    
    /**
     * 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.
     *
     * It also means that 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
     * to execute a task than only once at the beginning of the script.
     *
     * 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 $time_limit
     *   An integer specifying the new time limit, in seconds. A value of 0
     *   indicates unlimited execution time.
     *
     * @ingroup php_wrappers
     */
    function drupal_set_time_limit($time_limit) {
      if (function_exists('set_time_limit')) {
        @set_time_limit($time_limit);
      }
    }
    
    /**
     * Returns the path to a system item (module, theme, etc.).
     *
     * @param $type
     *   The type of the item (i.e. theme, theme_engine, module, profile).
     * @param $name
     *   The name of the item for which the path is requested.
     *
     * @return
     *   The path to the requested item.
     */
    function drupal_get_path($type, $name) {
      return dirname(drupal_get_filename($type, $name));
    }
    
    /**
     * Return the base URL path (i.e., directory) of the Drupal installation.
     *
     * base_path() prefixes and suffixes a "/" onto the returned path if the path is
     * not empty. At the very least, this will return "/".
     *
     * Examples:
     * - http://example.com returns "/" because the path is empty.
     * - http://example.com/drupal/folder returns "/drupal/folder/".
     */
    function base_path() {
      return $GLOBALS['base_path'];
    }
    
    /**
     * Add a LINK tag with a distinct 'rel' attribute to the page's HEAD.
     *
     * This function can be called as long the HTML header hasn't been sent,
     * which on normal pages is up through the preprocess step of theme('html').
     * Adding a link will overwrite a prior link with the exact same 'rel' and
     * 'href' attributes.
     *
     * @param $attributes
     *   Associative array of element attributes including 'href' and 'rel'.
     * @param $header
     *   Optional flag to determine if a HTTP 'Link:' header should be sent.
     */
    function drupal_add_html_head_link($attributes, $header = FALSE) {
      $element = array(
        '#tag' => 'link',
        '#attributes' => $attributes,
      );
      $href = $attributes['href'];
    
      if ($header) {
        // Also add a HTTP header "Link:".
        $href = '<' . check_plain($attributes['href']) . '>;';
        unset($attributes['href']);
        $element['#attached']['drupal_add_http_header'][] = array('Link',  $href . drupal_http_header_attributes($attributes), TRUE);
      }
    
      drupal_add_html_head($element, 'drupal_add_html_head_link:' . $attributes['rel'] . ':' . $href);
    }
    
    /**
     * Adds a cascading stylesheet to the stylesheet queue.
     *
     * Calling drupal_static_reset('drupal_add_css') will clear all cascading
     * stylesheets added so far.
     *
     * If CSS aggregation/compression is enabled, all cascading style sheets added
     * with $options['preprocess'] set to TRUE will be merged into one aggregate
     * file and compressed by removing all extraneous white space.
     * Preprocessed inline stylesheets will not be aggregated into this single file;
     * instead, they are just compressed upon output on the page. Externally hosted
     * stylesheets are never aggregated or compressed.
     *
     * The reason for aggregating the files is outlined quite thoroughly here:
     * http://www.die.net/musings/page_load_time/ "Load fewer external objects. Due
     * to request overhead, one bigger file just loads faster than two smaller ones
     * half its size."
     *
     * $options['preprocess'] should be only set to TRUE when a file is required for
     * all typical visitors and most pages of a site. It is critical that all
     * preprocessed files are added unconditionally on every page, even if the
     * files do not happen to be needed on a page. This is normally done by calling
     * drupal_add_css() in a hook_init() implementation.
     *
     * Non-preprocessed files should only be added to the page when they are
     * actually needed.
     *
     * @param $data
     *   (optional) The stylesheet data to be added, depending on what is passed
     *   through to the $options['type'] parameter:
     *   - 'file': The path to the CSS file relative to the base_path(), or a
     *     stream wrapper URI. For example: "modules/devel/devel.css" or
     *     "public://generated_css/stylesheet_1.css". Note that Modules should
     *     always prefix the names of their CSS files with the module name; for
     *     example, system-menus.css rather than simply menus.css. Themes can
     *     override module-supplied CSS files based on their filenames, and this
     *     prefixing helps prevent confusing name collisions for theme developers.
     *     See drupal_get_css() where the overrides are performed. Also, if the
     *     direction of the current language is right-to-left (Hebrew, Arabic,
     *     etc.), the function will also look for an RTL CSS file and append it to
     *     the list. The name of this file should have an '-rtl.css' suffix.  For
     *     example a CSS file called 'mymodule-name.css' will have a
     *     'mymodule-name-rtl.css' file added to the list, if exists in the same
     *     directory. This CSS file should contain overrides for properties which
     *     should be reversed or otherwise different in a right-to-left display.
     *   - 'inline': A string of CSS that should be placed in the given scope. Note
     *     that it is better practice to use 'file' stylesheets, rather than
     *     'inline', as the CSS would then be aggregated and cached.
     *   - 'external': The absolute path to an external CSS file that is not hosted
     *     on the local server. These files will not be aggregated if CSS
     *     aggregation is enabled.
     * @param $options
     *   (optional) A string defining the 'type' of CSS that is being added in the
     *   $data parameter ('file', 'inline', or 'external'), or an array which can
     *   have any or all of the following keys:
     *   - 'type': The type of stylesheet being added. Available options are 'file',
     *     'inline' or 'external'. Defaults to 'file'.
     *   - 'basename': Force a basename for the file being added. Modules are
     *     expected to use stylesheets with unique filenames, but integration of
     *     external libraries may make this impossible. The basename of
     *     'modules/node/node.css' is 'node.css'. If the external library "node.js"
     *     ships with a 'node.css', then a different, unique basename would be
     *     'node.js.css'.
     *   - 'group': A number identifying the group in which to add the stylesheet.
     *     Available constants are:
     *     - CSS_SYSTEM: Any system-layer CSS.
     *     - CSS_DEFAULT: Any module-layer CSS.
     *     - CSS_THEME: Any theme-layer CSS.
     *     The group number serves as a weight: the markup for loading a stylesheet
     *     within a lower weight group is output to the page before the markup for
     *     loading a stylesheet within a higher weight group, so CSS within higher
     *     weight groups take precendence over CSS within lower weight groups.
     *   - 'every_page': For optimal front-end performance when aggregation is
     *     enabled, this should be set to TRUE if the stylesheet is present on every
     *     page of the website for users for whom it is present at all. This
     *     defaults to FALSE. It is set to TRUE for stylesheets added via module and
     *     theme .info files. Modules that add stylesheets within hook_init()
     *     implementations, or from other code that ensures that the stylesheet is
     *     added to all website pages, should also set this flag to TRUE. All
     *     stylesheets within the same group that have the 'every_page' flag set to
     *     TRUE and do not have 'preprocess' set to FALSE are aggregated together
     *     into a single aggregate file, and that aggregate file can be reused
     *     across a user's entire site visit, leading to faster navigation between
     *     pages. However, stylesheets that are only needed on pages less frequently
     *     visited, can be added by code that only runs for those particular pages,
     *     and that code should not set the 'every_page' flag. This minimizes the
     *     size of the aggregate file that the user needs to download when first
     *     visiting the website. Stylesheets without the 'every_page' flag are
     *     aggregated into a separate aggregate file. This other aggregate file is
     *     likely to change from page to page, and each new aggregate file needs to
     *     be downloaded when first encountered, so it should be kept relatively
     *     small by ensuring that most commonly needed stylesheets are added to
     *     every page.
     *   - 'weight': The weight of the stylesheet specifies the order in which the
     *     CSS will appear relative to other stylesheets with the same group and
     *     'every_page' flag. The exact ordering of stylesheets is as follows:
     *     - First by group.
     *     - Then by the 'every_page' flag, with TRUE coming before FALSE.
     *     - Then by weight.
     *     - Then by the order in which the CSS was added. For example, all else
     *       being the same, a stylesheet added by a call to drupal_add_css() that
     *       happened later in the page request gets added to the page after one for
     *       which drupal_add_css() happened earlier in the page request.
     *   - 'media': The media type for the stylesheet, e.g., all, print, screen.
     *     Defaults to 'all'.
     *   - 'preprocess': If TRUE and CSS aggregation/compression is enabled, the
     *     styles will be aggregated and compressed. Defaults to TRUE.
     *   - 'browsers': An array containing information specifying which browsers
     *     should load the CSS item. See drupal_pre_render_conditional_comments()
     *     for details.
     *
     * @return
     *   An array of queued cascading stylesheets.
     *
     * @see drupal_get_css()
     */
    function drupal_add_css($data = NULL, $options = NULL) {
      $css = &drupal_static(__FUNCTION__, array());
    
      // Construct the options, taking the defaults into consideration.
      if (isset($options)) {
        if (!is_array($options)) {
          $options = array('type' => $options);
        }
      }
      else {
        $options = array();
      }
    
      // Create an array of CSS files for each media type first, since each type needs to be served
      // to the browser differently.
      if (isset($data)) {
        $options += array(
          'type' => 'file',
          'group' => CSS_DEFAULT,
          'weight' => 0,
          'every_page' => FALSE,
          'media' => 'all',
          'preprocess' => TRUE,
          'data' => $data,
          'browsers' => array(),
        );
        $options['browsers'] += array(
          'IE' => TRUE,
          '!IE' => TRUE,
        );
    
        // Files with a query string cannot be preprocessed.
        if ($options['type'] === 'file' && $options['preprocess'] && strpos($options['data'], '?') !== FALSE) {
          $options['preprocess'] = FALSE;
        }
    
        // Always add a tiny value to the weight, to conserve the insertion order.
        $options['weight'] += count($css) / 1000;
    
        // Add the data to the CSS array depending on the type.
        switch ($options['type']) {
          case 'inline':
            // For inline stylesheets, we don't want to use the $data as the array
            // key as $data could be a very long string of CSS.
            $css[] = $options;
            break;
          default:
            // Local and external files must keep their name as the associative key
            // so the same CSS file is not be added twice.
            $css[$data] = $options;
        }
      }
    
      return $css;
    }
    
    /**
     * Returns a themed representation of all stylesheets that should be attached to the page.
     *
     * It loads the CSS in order, with 'module' first, then 'theme' afterwards.
     * This ensures proper cascading of styles so themes can easily override
     * module styles through CSS selectors.
     *
     * Themes may replace module-defined CSS files by adding a stylesheet with the
     * same filename. For example, themes/bartik/system-menus.css would replace
     * modules/system/system-menus.css. This allows themes to override complete
     * CSS files, rather than specific selectors, when necessary.
     *
     * If the original CSS file is being overridden by a theme, the theme is
     * responsible for supplying an accompanying RTL CSS file to replace the
     * module's.
     *
     * @param $css
     *   (optional) An array of CSS files. If no array is provided, the default
     *   stylesheets array is used instead.
     * @param $skip_alter
     *   (optional) If set to TRUE, this function skips calling drupal_alter() on
     *   $css, useful when the calling function passes a $css array that has already
     *   been altered.
     *
     * @return
     *   A string of XHTML CSS tags.
     *
     * @see drupal_add_css()
     */
    function drupal_get_css($css = NULL, $skip_alter = FALSE) {
      if (!isset($css)) {
        $css = drupal_add_css();
      }
    
      // Allow modules and themes to alter the CSS items.
      if (!$skip_alter) {
        drupal_alter('css', $css);
      }
    
      // Sort CSS items, so that they appear in the correct order.
      uasort($css, 'drupal_sort_css_js');
    
      // Remove the overridden CSS files. Later CSS files override former ones.
      $previous_item = array();
      foreach ($css as $key => $item) {
        if ($item['type'] == 'file') {
          // If defined, force a unique basename for this file.
          $basename = isset($item['basename']) ? $item['basename'] : basename($item['data']);
          if (isset($previous_item[$basename])) {
            // Remove the previous item that shared the same base name.
            unset($css[$previous_item[$basename]]);
          }
          $previous_item[$basename] = $key;
        }
      }
    
      // Render the HTML needed to load the CSS.
      $styles = array(
        '#type' => 'styles',
        '#items' => $css,
      );
    
      // Provide the page with information about the individual CSS files used,
      // information not otherwise available when CSS aggregation is enabled.
      $setting['ajaxPageState']['css'] = array_fill_keys(array_keys($css), 1);
      $styles['#attached']['js'][] = array('type' => 'setting', 'data' => $setting);
    
      return drupal_render($styles);
    }
    
    /**
     * Function used by uasort to sort the array structures returned by drupal_add_css() and drupal_add_js().
     *
     * This sort order helps optimize front-end performance while providing modules
     * and themes with the necessary control for ordering the CSS and JavaScript
     * appearing on a page.
     */
    function drupal_sort_css_js($a, $b) {
      // First order by group, so that, for example, all items in the CSS_SYSTEM
      // group appear before items in the CSS_DEFAULT group, which appear before
      // all items in the CSS_THEME group. Modules may create additional groups by
      // defining their own constants.
      if ($a['group'] < $b['group']) {
        return -1;
      }
      elseif ($a['group'] > $b['group']) {
        return 1;
      }
      // Within a group, order all infrequently needed, page-specific files after
      // common files needed throughout the website. Separating this way allows for
      // the aggregate file generated for all of the common files to be reused
      // across a site visit without being cut by a page using a less common file.
      elseif ($a['every_page'] && !$b['every_page']) {
        return -1;
      }
      elseif (!$a['every_page'] && $b['every_page']) {
        return 1;
      }
      // Finally, order by weight.
      elseif ($a['weight'] < $b['weight']) {
        return -1;
      }
      elseif ($a['weight'] > $b['weight']) {
        return 1;
      }
      else {
        return 0;
      }
    }
    
    /**
     * Default callback to group CSS items.
     *
     * This function arranges the CSS items that are in the #items property of the
     * styles element into groups. Arranging the CSS items into groups serves two
     * purposes. When aggregation is enabled, files within a group are aggregated
     * into a single file, significantly improving page loading performance by
     * minimizing network traffic overhead. When aggregation is disabled, grouping
     * allows multiple files to be loaded from a single STYLE tag, enabling sites
     * with many modules enabled or a complex theme being used to stay within IE's
     * 31 CSS inclusion tag limit: http://drupal.org/node/228818.
     *
     * This function puts multiple items into the same group if they are groupable
     * and if they are for the same 'media' and 'browsers'. Items of the 'file' type
     * are groupable if their 'preprocess' flag is TRUE, items of the 'inline' type
     * are always groupable, and items of the 'external' type are never groupable.
     * This function also ensures that the process of grouping items does not change
     * their relative order. This requirement may result in multiple groups for the
     * same type, media, and browsers, if needed to accomodate other items in
     * between.
     *
     * @param $css
     *   An array of CSS items, as returned by drupal_add_css(), but after
     *   alteration performed by drupal_get_css().
     *
     * @return
     *   An array of CSS groups. Each group contains the same keys (e.g., 'media',
     *   'data', etc.) as a CSS item from the $css parameter, with the value of
     *   each key applying to the group as a whole. Each group also contains an
     *   'items' key, which is the subset of items from $css that are in the group.
     *
     * @see drupal_pre_render_styles()
     */
    function drupal_group_css($css) {
      $groups = array();
      // If a group can contain multiple items, we track the information that must
      // be the same for each item in the group, so that when we iterate the next
      // item, we can determine if it can be put into the current group, or if a
      // new group needs to be made for it.
      $current_group_keys = NULL;
      // When creating a new group, we pre-increment $i, so by initializing it to
      // -1, the first group will have index 0.
      $i = -1;
      foreach ($css as $item) {
        // The browsers for which the CSS item needs to be loaded is part of the
        // information that determines when a new group is needed, but the order of
        // keys in the array doesn't matter, and we don't want a new group if all
        // that's different is that order.
        ksort($item['browsers']);
    
        // If the item can be grouped with other items, set $group_keys to an array
        // of information that must be the same for all items in its group. If the
        // item can't be grouped with other items, set $group_keys to FALSE. We
        // put items into a group that can be aggregated together: whether they will
        // be aggregated is up to the _drupal_css_aggregate() function or an
        // override of that function specified in hook_css_alter(), but regardless
        // of the details of that function, a group represents items that can be
        // aggregated. Since a group may be rendered with a single HTML tag, all
        // items in the group must share the same information that would need to be
        // part of that HTML tag.
        switch ($item['type']) {
          case 'file':
            // Group file items if their 'preprocess' flag is TRUE.
            // Help ensure maximum reuse of aggregate files by only grouping
            // together items that share the same 'group' value and 'every_page'
            // flag. See drupal_add_css() for details about that.
            $group_keys = $item['preprocess'] ? array($item['type'], $item['group'], $item['every_page'], $item['media'], $item['browsers']) : FALSE;
            break;
          case 'inline':
            // Always group inline items.
            $group_keys = array($item['type'], $item['media'], $item['browsers']);
            break;
          case 'external':
            // Do not group external items.
            $group_keys = FALSE;
            break;
        }
    
        // If the group keys don't match the most recent group we're working with,
        // then a new group must be made.
        if ($group_keys !== $current_group_keys) {
          $i++;
          // Initialize the new group with the same properties as the first item
          // being placed into it. The item's 'data' and 'weight' properties are
          // unique to the item and should not be carried over to the group.
          $groups[$i] = $item;
          unset($groups[$i]['data'], $groups[$i]['weight']);
          $groups[$i]['items'] = array();
          $current_group_keys = $group_keys ? $group_keys : NULL;
        }
    
        // Add the item to the current group.
        $groups[$i]['items'][] = $item;
      }
      return $groups;
    }
    
    /**
     * Default callback to aggregate CSS files and inline content.
     *
     * Having the browser load fewer CSS files results in much faster page loads
     * than when it loads many small files. This function aggregates files within
     * the same group into a single file unless the site-wide setting to do so is
     * disabled (commonly the case during site development). To optimize download,
     * it also compresses the aggregate files by removing comments, whitespace, and
     * other unnecessary content. Additionally, this functions aggregates inline
     * content together, regardless of the site-wide aggregation setting.
     *
     * @param $css_groups
     *   An array of CSS groups as returned by drupal_group_css(). This function
     *   modifies the group's 'data' property for each group that is aggregated.
     *
     * @see drupal_group_css()
     * @see drupal_pre_render_styles()
     */
    function drupal_aggregate_css(&$css_groups) {
      $preprocess_css = (variable_get('preprocess_css', FALSE) && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update'));
    
      // For each group that needs aggregation, aggregate its items.
      foreach ($css_groups as $key => $group) {
        switch ($group['type']) {
          // If a file group can be aggregated into a single file, do so, and set
          // the group's data property to the file path of the aggregate file.
          case 'file':
            if ($group['preprocess'] && $preprocess_css) {
              $css_groups[$key]['data'] = drupal_build_css_cache($group['items']);
            }
            break;
          // Aggregate all inline CSS content into the group's data property.
          case 'inline':
            $css_groups[$key]['data'] = '';
            foreach ($group['items'] as $item) {
              $css_groups[$key]['data'] .= drupal_load_stylesheet_content($item['data'], $item['preprocess']);
            }
            break;
        }
      }
    }
    
    /**
     * #pre_render callback to add the elements needed for CSS tags to be rendered.
     *
     * For production websites, LINK tags are preferable to STYLE tags with @import
     * statements, because:
     * - They are the standard tag intended for linking to a resource.
     * - On Firefox 2 and perhaps other browsers, CSS files included with @import
     *   statements don't get saved when saving the complete web page for offline
     *   use: http://drupal.org/node/145218.
     * - On IE, if only LINK tags and no @import statements are used, all the CSS
     *   files are downloaded in parallel, resulting in faster page load, but if
     *   @import statements are used and span across multiple STYLE tags, all the
     *   ones from one STYLE tag must be downloaded before downloading begins for
     *   the next STYLE tag. Furthermore, IE7 does not support media declaration on
     *   the @import statement, so multiple STYLE tags must be used when different
     *   files are for different media types. Non-IE browsers always download in
     *   parallel, so this is an IE-specific performance quirk:
     *   http://www.stevesouders.com/blog/2009/04/09/dont-use-import/.
     *
     * However, IE has an annoying limit of 31 total CSS inclusion tags
     * (http://drupal.org/node/228818) and LINK tags are limited to one file per
     * tag, whereas STYLE tags can contain multiple @import statements allowing
     * multiple files to be loaded per tag. When CSS aggregation is disabled, a
     * Drupal site can easily have more than 31 CSS files that need to be loaded, so
     * using LINK tags exclusively would result in a site that would display
     * incorrectly in IE. Depending on different needs, different strategies can be
     * employed to decide when to use LINK tags and when to use STYLE tags.
     *
     * The strategy employed by this function is to use LINK tags for all aggregate
     * files and for all files that cannot be aggregated (e.g., if 'preprocess' is
     * set to FALSE or the type is 'external'), and to use STYLE tags for groups
     * of files that could be aggregated together but aren't (e.g., if the site-wide
     * aggregation setting is disabled). This results in all LINK tags when
     * aggregation is enabled, a guarantee that as many or only slightly more tags
     * are used with aggregation disabled than enabled (so that if the limit were to
     * be crossed with aggregation enabled, the site developer would also notice the
     * problem while aggregation is disabled), and an easy way for a developer to
     * view HTML source while aggregation is disabled and know what files will be
     * aggregated together when aggregation becomes enabled.
     *
     * This function evaluates the aggregation enabled/disabled condition on a group
     * by group basis by testing whether an aggregate file has been made for the
     * group rather than by testing the site-wide aggregation setting. This allows
     * this function to work correctly even if modules have implemented custom
     * logic for grouping and aggregating files.
     *
     * @param $element
     *   A render array containing:
     *   - '#items': The CSS items as returned by drupal_add_css() and altered by
     *     drupal_get_css().
     *   - '#group_callback': A function to call to group #items to enable the use
     *     of fewer tags by aggregating files and/or using multiple @import
     *     statements within a single tag.
     *   - '#aggregate_callback': A function to call to aggregate the items within
     *     the groups arranged by the #group_callback function.
     *
     * @return
     *   A render array that will render to a string of XHTML CSS tags.
     *
     * @see drupal_get_css()
     */
    function drupal_pre_render_styles($elements) {
      // Group and aggregate the items.
      if (isset($elements['#group_callback'])) {
        $elements['#groups'] = $elements['#group_callback']($elements['#items']);
      }
      if (isset($elements['#aggregate_callback'])) {
        $elements['#aggregate_callback']($elements['#groups']);
      }
    
      // A dummy query-string is added to filenames, to gain control over
      // browser-caching. The string changes on every update or full cache
      // flush, forcing browsers to load a new copy of the files, as the
      // URL changed.
      $query_string = variable_get('css_js_query_string', '0');
    
      // For inline CSS to validate as XHTML, all CSS containing XHTML needs to be
      // wrapped in CDATA. To make that backwards compatible with HTML 4, we need to
      // comment out the CDATA-tag.
      $embed_prefix = "\n<!--/*--><![CDATA[/*><!--*/\n";
      $embed_suffix = "\n/*]]>*/-->\n";
    
      // Defaults for LINK and STYLE elements.
      $link_element_defaults = array(
        '#type' => 'html_tag',
        '#tag' => 'link',
        '#attributes' => array(
          'type' => 'text/css',
          'rel' => 'stylesheet',
        ),
      );
      $style_element_defaults = array(
        '#type' => 'html_tag',
        '#tag' => 'style',
        '#attributes' => array(
          'type' => 'text/css',
        ),
      );
    
      // Loop through each group.
      foreach ($elements['#groups'] as $group) {
        switch ($group['type']) {
          // For file items, there are three possibilites.
          // - The group has been aggregated: in this case, output a LINK tag for
          //   the aggregate file.
          // - The group can be aggregated but has not been (most likely because
          //   the site administrator disabled the site-wide setting): in this case,
          //   output as few STYLE tags for the group as possible, using @import
          //   statement for each file in the group. This enables us to stay within
          //   IE's limit of 31 total CSS inclusion tags.
          // - The group contains items not eligible for aggregation (their
          //   'preprocess' flag has been set to FALSE): in this case, output a LINK
          //   tag for each file.
          case 'file':
            // The group has been aggregated into a single file: output a LINK tag
            // for the aggregate file.
            if (isset($group['data'])) {
              $element = $link_element_defaults;
              $element['#attributes']['href'] = file_create_url($group['data']);
              $element['#attributes']['media'] = $group['media'];
              $element['#browsers'] = $group['browsers'];
              $elements[] = $element;
            }
            // The group can be aggregated, but hasn't been: combine multiple items
            // into as few STYLE tags as possible.
            elseif ($group['preprocess']) {
              $import = array();
              foreach ($group['items'] as $item) {
                // A theme's .info file may have an entry for a file that doesn't
                // exist as a way of overriding a module or base theme CSS file from
                // being added to the page. Normally, file_exists() calls that need
                // to run for every page request should be minimized, but this one
                // is okay, because it only runs when CSS aggregation is disabled.
                // On a server under heavy enough load that file_exists() calls need
                // to be minimized, CSS aggregation should be enabled, in which case
                // this code is not run. When aggregation is enabled,
                // drupal_load_stylesheet() checks file_exists(), but only when
                // building the aggregate file, which is then reused for many page
                // requests.
                if (file_exists($item['data'])) {
                  // The dummy query string needs to be added to the URL to control
                  // browser-caching. IE7 does not support a media type on the
                  // @import statement, so we instead specify the media for the
                  // group on the STYLE tag.
                  $import[] = '@import url("' . check_plain(file_create_url($item['data']) . '?' . $query_string) . '");';
                }
              }
              // In addition to IE's limit of 31 total CSS inclusion tags, it also
              // has a limit of 31 @import statements per STYLE tag.
              while (!empty($import)) {
                $import_batch = array_slice($import, 0, 31);
                $import = array_slice($import, 31);
                $element = $style_element_defaults;
                $element['#value'] = implode("\n", $import_batch);
                $element['#attributes']['media'] = $group['media'];
                $element['#browsers'] = $group['browsers'];
                $elements[] = $element;
              }
            }
            // The group contains items ineligible for aggregation: output a LINK
            // tag for each file.
            else {
              foreach ($group['items'] as $item) {
                $element = $link_element_defaults;
                // We do not check file_exists() here, because this code runs for
                // files whose 'preprocess' is set to FALSE, and therefore, even
                // when aggregation is enabled, and we want to avoid needlessly
                // taxing a server that may be under heavy load. The file_exists()
                // performed above for files whose 'preprocess' is TRUE is done for
                // the benefit of theme .info files, but code that deals with files
                // whose 'preprocess' is FALSE is responsible for ensuring the file
                // exists.
                // The dummy query string needs to be added to the URL to control
                // browser-caching.
                $query_string_separator = (strpos($item['data'], '?') !== FALSE) ? '&' : '?';
                $element['#attributes']['href'] = file_create_url($item['data']) . $query_string_separator . $query_string;
                $element['#attributes']['media'] = $item['media'];
                $element['#browsers'] = $group['browsers'];
                $elements[] = $element;
              }
            }
            break;
          // For inline content, the 'data' property contains the CSS content. If
          // the group's 'data' property is set, then output it in a single STYLE
          // tag. Otherwise, output a separate STYLE tag for each item.
          case 'inline':
            if (isset($group['data'])) {
              $element = $style_element_defaults;
              $element['#value'] = $group['data'];
              $element['#value_prefix'] = $embed_prefix;
              $element['#value_suffix'] = $embed_suffix;
              $element['#attributes']['media'] = $group['media'];
              $element['#browsers'] = $group['browsers'];
              $elements[] = $element;
            }
            else {
              foreach ($group['items'] as $item) {
                $element = $style_element_defaults;
                $element['#value'] = $item['data'];
                $element['#value_prefix'] = $embed_prefix;
                $element['#value_suffix'] = $embed_suffix;
                $element['#attributes']['media'] = $item['media'];
                $element['#browsers'] = $group['browsers'];
                $elements[] = $element;
              }
            }
            break;
          // Output a LINK tag for each external item. The item's 'data' property
          // contains the full URL.
          case 'external':
            foreach ($group['items'] as $item) {
              $element = $link_element_defaults;
              $element['#attributes']['href'] = $item['data'];
              $element['#attributes']['media'] = $item['media'];
              $element['#browsers'] = $group['browsers'];
              $elements[] = $element;
            }
            break;
        }
      }
    
      return $elements;
    }
    
    /**
     * Aggregates and optimizes CSS files into a cache file in the files directory.
     *
     * The file name for the CSS cache file is generated from the hash of the
     * aggregated contents of the files in $css. This forces proxies and browsers
     * to download new CSS when the CSS changes.
     *
     * The cache file name is retrieved on a page load via a lookup variable that
     * contains an associative array. The array key is the hash of the file names
     * in $css while the value is the cache file name. The cache file is generated
     * in two cases. First, if there is no file name value for the key, which will
     * happen if a new file name has been added to $css or after the lookup
     * variable is emptied to force a rebuild of the cache.  Second, the cache
     * file is generated if it is missing on disk. Old cache files are not deleted
     * immediately when the lookup variable is emptied, but are deleted after a set
     * period by drupal_delete_file_if_stale(). This ensures that files referenced
     * by a cached page will still be available.
     *
     * @param $css
     *   An array of CSS files to aggregate and compress into one file.
     *
     * @return
     *   The URI of the CSS cache file, or FALSE if the file could not be saved.
     */
    function drupal_build_css_cache($css) {
      $data = '';
      $uri = '';
      $map = variable_get('drupal_css_cache_files', array());
      $key = hash('sha256', serialize($css));
      if (isset($map[$key])) {
        $uri = $map[$key];
      }
    
      if (empty($uri) || !file_exists($uri)) {
        // Build aggregate CSS file.
        foreach ($css as $stylesheet) {
          // Only 'file' stylesheets can be aggregated.
          if ($stylesheet['type'] == 'file') {
            $contents = drupal_load_stylesheet($stylesheet['data'], TRUE);
    
            // Build the base URL of this CSS file: start with the full URL.
            $css_base_url = file_create_url($stylesheet['data']);
            // Move to the parent.
            $css_base_url = substr($css_base_url, 0, strrpos($css_base_url, '/'));
            // Simplify to a relative URL if the stylesheet URL starts with the
            // base URL of the website.
            if (substr($css_base_url, 0, strlen($GLOBALS['base_root'])) == $GLOBALS['base_root']) {
              $css_base_url = substr($css_base_url, strlen($GLOBALS['base_root']));
            }
    
            _drupal_build_css_path(NULL, $css_base_url . '/');
            // Anchor all paths in the CSS with its base URL, ignoring external and absolute paths.
            $data .= preg_replace_callback('/url\(\s*[\'"]?(?![a-z]+:|\/+)([^\'")]+)[\'"]?\s*\)/i', '_drupal_build_css_path', $contents);
          }
        }
    
        // Per the W3C specification at http://www.w3.org/TR/REC-CSS2/cascade.html#at-import,
        // @import rules must proceed any other style, so we move those to the top.
        $regexp = '/@import[^;]+;/i';
        preg_match_all($regexp, $data, $matches);
        $data = preg_replace($regexp, '', $data);
        $data = implode('', $matches[0]) . $data;
    
        // Prefix filename to prevent blocking by firewalls which reject files
        // starting with "ad*".
        $filename = 'css_' . drupal_hash_base64($data) . '.css';
        // Create the css/ within the files folder.
        $csspath = 'public://css';
        $uri = $csspath . '/' . $filename;
        // Create the CSS file.
        file_prepare_directory($csspath, FILE_CREATE_DIRECTORY);
        if (!file_exists($uri) && !file_unmanaged_save_data($data, $uri, FILE_EXISTS_REPLACE)) {
          return FALSE;
        }
        // If CSS gzip compression is enabled, clean URLs are enabled (which means
        // that rewrite rules are working) and the zlib extension is available then
        // create a gzipped version of this file. This file is served conditionally
        // to browsers that accept gzip using .htaccess rules.
        if (variable_get('css_gzip_compression', TRUE) && variable_get('clean_url', 0) && extension_loaded('zlib')) {
          if (!file_exists($uri . '.gz') && !file_unmanaged_save_data(gzencode($data, 9, FORCE_GZIP), $uri . '.gz', FILE_EXISTS_REPLACE)) {
            return FALSE;
          }
        }
        // Save the updated map.
        $map[$key] = $uri;
        variable_set('drupal_css_cache_files', $map);
      }
      return $uri;
    }
    
    /**
     * Helper function for drupal_build_css_cache().
     *
     * This function will prefix all paths within a CSS file.
     */
    function _drupal_build_css_path($matches, $base = NULL) {
      $_base = &drupal_static(__FUNCTION__);
      // Store base path for preg_replace_callback.
      if (isset($base)) {
        $_base = $base;
      }
    
      // Prefix with base and remove '../' segments where possible.
      $path = $_base . $matches[1];
      $last = '';
      while ($path != $last) {
        $last = $path;
        $path = preg_replace('`(^|/)(?!\.\./)([^/]+)/\.\./`', '$1', $path);
      }
      return 'url(' . $path . ')';
    }
    
    /**
     * Loads the stylesheet and resolves all @import commands.
     *
     * Loads a stylesheet and replaces @import commands with the contents of the
     * imported file. Use this instead of file_get_contents when processing
     * stylesheets.
     *
     * The returned contents are compressed removing white space and comments only
     * when CSS aggregation is enabled. This optimization will not apply for
     * color.module enabled themes with CSS aggregation turned off.
     *
     * @param $file
     *   Name of the stylesheet to be processed.
     * @param $optimize
     *   Defines if CSS contents should be compressed or not.
     * @param $reset_basepath
     *   Used internally to facilitate recursive resolution of @import commands.
     *
     * @return
     *   Contents of the stylesheet, including any resolved @import commands.
     */
    function drupal_load_stylesheet($file, $optimize = NULL, $reset_basepath = TRUE) {
      // These statics are not cache variables, so we don't use drupal_static().
      static $_optimize, $basepath;
      if ($reset_basepath) {
        $basepath = '';
      }
      // Store the value of $optimize for preg_replace_callback with nested
      // @import loops.
      if (isset($optimize)) {
        $_optimize = $optimize;
      }
    
      // Stylesheets are relative one to each other. Start by adding a base path
      // prefix provided by the parent stylesheet (if necessary).
      if ($basepath && !file_uri_scheme($file)) {
        $file = $basepath . '/' . $file;
      }
      $basepath = dirname($file);
    
      // Load the CSS stylesheet. We suppress errors because themes may specify
      // stylesheets in their .info file that don't exist in the theme's path,
      // but are merely there to disable certain module CSS files.
      if ($contents = @file_get_contents($file)) {
        // Return the processed stylesheet.
        return drupal_load_stylesheet_content($contents, $_optimize);
      }
    
      return '';
    }
    
    /**
     * Process the contents of a stylesheet for aggregation.
     *
     * @param $contents
     *   The contents of the stylesheet.
     * @param $optimize
     *   (optional) Boolean whether CSS contents should be minified. Defaults to
     *   FALSE.
     * @return
     *   Contents of the stylesheet including the imported stylesheets.
     */
    function drupal_load_stylesheet_content($contents, $optimize = FALSE) {
      // Remove multiple charset declarations for standards compliance (and fixing Safari problems).
      $contents = preg_replace('/^@charset\s+[\'"](\S*)\b[\'"];/i', '', $contents);
    
      if ($optimize) {
        // Perform some safe CSS optimizations.
        // Regexp to match comment blocks.
        $comment     = '/\*[^*]*\*+(?:[^/*][^*]*\*+)*/';
        // Regexp to match double quoted strings.
        $double_quot = '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"';
        // Regexp to match single quoted strings.
        $single_quot = "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'";
        // Strip all comment blocks, but keep double/single quoted strings.
        $contents = preg_replace(
          "<($double_quot|$single_quot)|$comment>Ss",
          "$1",
          $contents
        );
        // Remove certain whitespace.
        // There are different conditions for removing leading and trailing
        // whitespace.
        // @see http://php.net/manual/en/regexp.reference.subpatterns.php
        $contents = preg_replace('<
          # Strip leading and trailing whitespace.
            \s*([@{};,])\s*
          # Strip only leading whitespace from:
          # - Closing parenthesis: Retain "@media (bar) and foo".
          | \s+([\)])
          # Strip only trailing whitespace from:
          # - Opening parenthesis: Retain "@media (bar) and foo".
          # - Colon: Retain :pseudo-selectors.
          | ([\(:])\s+
        >xS',
          // Only one of the three capturing groups will match, so its reference
          // will contain the wanted value and the references for the
          // two non-matching groups will be replaced with empty strings.
          '$1$2$3',
          $contents
        );
        // End the file with a new line.
        $contents = trim($contents);
        $contents .= "\n";
      }
    
      // Replaces @import commands with the actual stylesheet content.
      // This happens recursively but omits external files.
      $contents = preg_replace_callback('/@import\s*(?:url\(\s*)?[\'"]?(?![a-z]+:)([^\'"\()]+)[\'"]?\s*\)?\s*;/', '_drupal_load_stylesheet', $contents);
      return $contents;
    }
    
    /**
     * Loads stylesheets recursively and returns contents with corrected paths.
     *
     * This function is used for recursive loading of stylesheets and
     * returns the stylesheet content with all url() paths corrected.
     */
    function _drupal_load_stylesheet($matches) {
      $filename = $matches[1];
      // Load the imported stylesheet and replace @import commands in there as well.
      $file = drupal_load_stylesheet($filename, NULL, FALSE);
    
      // Determine the file's directory.
      $directory = dirname($filename);
      // If the file is in the current directory, make sure '.' doesn't appear in
      // the url() path.
      $directory = $directory == '.' ? '' : $directory .'/';
    
      // Alter all internal url() paths. Leave external paths alone. We don't need
      // to normalize absolute paths here (i.e. remove folder/... segments) because
      // that will be done later.
      return preg_replace('/url\(\s*([\'"]?)(?![a-z]+:|\/+)/i', 'url(\1'. $directory, $file);
    }
    
    /**
     * Deletes old cached CSS files.
     */
    function drupal_clear_css_cache() {
      variable_del('drupal_css_cache_files');
      file_scan_directory('public://css', '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
    }
    
    /**
     * Callback to delete files modified more than a set time ago.
     */
    function drupal_delete_file_if_stale($uri) {
      // Default stale file threshold is 30 days.
      if (REQUEST_TIME - filemtime($uri) > variable_get('drupal_stale_file_threshold', 2592000)) {
        file_unmanaged_delete($uri);
      }
    }
    
    /**
     * Prepare a string for use as a valid CSS identifier (element, class or ID name).
     *
     * http://www.w3.org/TR/CSS21/syndata.html#characters shows the syntax for valid
     * CSS identifiers (including element names, classes, and IDs in selectors.)
     *
     * @param $identifier
     *   The identifier to clean.
     * @param $filter
     *   An array of string replacements to use on the identifier.
     * @return
     *   The cleaned identifier.
     */
    function drupal_clean_css_identifier($identifier, $filter = array(' ' => '-', '_' => '-', '/' => '-', '[' => '-', ']' => '')) {
      // By default, we filter using Drupal's coding standards.
      $identifier = strtr($identifier, $filter);
    
      // Valid characters in a CSS identifier are:
      // - the hyphen (U+002D)
      // - a-z (U+0030 - U+0039)
      // - A-Z (U+0041 - U+005A)
      // - the underscore (U+005F)
      // - 0-9 (U+0061 - U+007A)
      // - ISO 10646 characters U+00A1 and higher
      // We strip out any character not in the above list.
      $identifier = preg_replace('/[^\x{002D}\x{0030}-\x{0039}\x{0041}-\x{005A}\x{005F}\x{0061}-\x{007A}\x{00A1}-\x{FFFF}]/u', '', $identifier);
    
      return $identifier;
    }
    
    /**
     * Prepare a string for use as a valid class name.
     *
     * Do not pass one string containing multiple classes as they will be
     * incorrectly concatenated with dashes, i.e. "one two" will become "one-two".
     *
     * @param $class
     *   The class name to clean.
     * @return
     *   The cleaned class name.
     */
    function drupal_html_class($class) {
      return drupal_clean_css_identifier(drupal_strtolower($class));
    }
    
    /**
     * Prepare a string for use as a valid HTML ID and guarantee uniqueness.
     *
     * 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.
     *
     * For already existing IDs, a counter is appended to the ID string. Therefore,
     * 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.
     *
     * Two consecutive hyphens separate the counter from the original ID. To manage
     * uniqueness across multiple Ajax requests on the same page, Ajax requests
     * POST an array of all IDs currently present on the page, which are used to
     * prime this function's cache upon first invocation.
     *
     * To allow reverse-parsing of IDs submitted via Ajax, any multiple consecutive
     * hyphens in the originally passed $id are replaced with a single hyphen.
     *
     * @param $id
     *   The ID to clean.
     *
     * @return
     *   The cleaned ID.
     */
    function drupal_html_id($id) {
      // If this is an Ajax request, then content returned by this page request will
      // be merged with content already on the base page. The HTML IDs must be
      // unique for the fully merged content. Therefore, initialize $seen_ids to
      // take into account IDs that are already in use on the base page.
      $seen_ids_init = &drupal_static(__FUNCTION__ . ':init');
      if (!isset($seen_ids_init)) {
        // Ideally, Drupal would provide an API to persist state information about
        // prior page requests in the database, and we'd be able to add this
        // function's $seen_ids static variable to that state information in order
        // to have it properly initialized for this page request. However, no such
        // page state API exists, so instead, ajax.js adds all of the in-use HTML
        // IDs to the POST data of Ajax submissions. Direct use of $_POST is
        // normally not recommended as it could open up security risks, but because
        // the raw POST data is cast to a number before being returned by this
        // function, this usage is safe.
        if (empty($_POST['ajax_html_ids'])) {
          $seen_ids_init = array();
        }
        else {
          // This function ensures uniqueness by appending a counter to the base id
          // requested by the calling function after the first occurrence of that
          // requested id. $_POST['ajax_html_ids'] contains the ids as they were
          // returned by this function, potentially with the appended counter, so
          // we parse that to reconstruct the $seen_ids array.
          foreach ($_POST['ajax_html_ids'] as $seen_id) {
            // We rely on '--' being used solely for separating a base id from the
            // counter, which this function ensures when returning an id.
            $parts = explode('--', $seen_id, 2);
            if (!empty($parts[1]) && is_numeric($parts[1])) {
              list($seen_id, $i) = $parts;
            }
            else {
              $i = 1;
            }
            if (!isset($seen_ids_init[$seen_id]) || ($i > $seen_ids_init[$seen_id])) {
              $seen_ids_init[$seen_id] = $i;
            }
          }
        }
      }
      $seen_ids = &drupal_static(__FUNCTION__, $seen_ids_init);
    
      $id = strtr(drupal_strtolower($id), array(' ' => '-', '_' => '-', '[' => '-', ']' => ''));
    
      // As defined in http://www.w3.org/TR/html4/types.html#type-name, HTML IDs can
      // only contain letters, digits ([0-9]), hyphens ("-"), underscores ("_"),
      // colons (":"), and periods ("."). We strip out any character not in that
      // list. Note that the CSS spec doesn't allow colons or periods in identifiers
      // (http://www.w3.org/TR/CSS21/syndata.html#characters), so we strip those two
      // characters as well.
      $id = preg_replace('/[^A-Za-z0-9\-_]/', '', $id);
    
      // Removing multiple consecutive hyphens.
      $id = preg_replace('/\-+/', '-', $id);
      // Ensure IDs are unique by appending a counter after the first occurrence.
      // The counter needs to be appended with a delimiter that does not exist in
      // the base ID. Requiring a unique delimiter helps ensure that we really do
      // return unique IDs and also helps us re-create the $seen_ids array during
      // Ajax requests.
      if (isset($seen_ids[$id])) {
        $id = $id . '--' . ++$seen_ids[$id];
      }
      else {
        $seen_ids[$id] = 1;
      }
    
      return $id;
    }
    
    /**
     * Provides a standard HTML class name that identifies a page region.
     *
     * It is recommended that template preprocess functions apply this class to any
     * page region that is output by the theme (Drupal core already handles this in
     * the standard template preprocess implementation). Standardizing the class
     * names in this way allows modules to implement certain features, such as
     * drag-and-drop or dynamic Ajax loading, in a theme-independent way.
     *
     * @param $region
     *   The name of the page region (for example, 'page_top' or 'content').
     *
     * @return
     *   An HTML class that identifies the region (for example, 'region-page-top'
     *   or 'region-content').
     *
     * @see template_preprocess_region()
     */
    function drupal_region_class($region) {
      return drupal_html_class("region-$region");
    }
    
    /**
     * Adds a JavaScript file, setting, or inline code to the page.
     *
     * The behavior of this function depends on the parameters it is called with.
     * Generally, it handles the addition of JavaScript to the page, either as
     * reference to an existing file or as inline code. The following actions can be
     * performed using this function:
     * - Add a file ('file'): Adds a reference to a JavaScript file to the page.
     * - Add inline JavaScript code ('inline'): Executes a piece of JavaScript code
     *   on the current page by placing the code directly in the page (for example,
     *   to tell the user that a new message arrived, by opening a pop up, alert
     *   box, etc.). This should only be used for JavaScript that cannot be executed
     *   from a file. When adding inline code, make sure that you are not relying on
     *   $() being the jQuery function.  Wrap your code in
     *   @code (function ($) {... })(jQuery); @endcode
     *   or use jQuery() instead of $().
     * - Add external JavaScript ('external'): Allows the inclusion of external
     *   JavaScript files that are not hosted on the local server. Note that these
     *   external JavaScript references do not get aggregated when preprocessing is
     *   on.
     * - Add settings ('setting'): Adds settings to Drupal's global storage of
     *   JavaScript settings. Per-page settings are required by some modules to
     *   function properly. All settings will be accessible at Drupal.settings.
     *
     * Examples:
     * @code
     *   drupal_add_js('misc/collapse.js');
     *   drupal_add_js('misc/collapse.js', 'file');
     *   drupal_add_js('jQuery(document).ready(function () { alert("Hello!"); });', 'inline');
     *   drupal_add_js('jQuery(document).ready(function () { alert("Hello!"); });',
     *     array('type' => 'inline', 'scope' => 'footer', 'weight' => 5)
     *   );
     *   drupal_add_js('http://example.com/example.js', 'external');
     *   drupal_add_js(array('myModule' => array('key' => 'value')), 'setting');
     * @endcode
     *
     * Calling drupal_static_reset('drupal_add_js') will clear all JavaScript added
     * so far.
     *
     * If JavaScript aggregation is enabled, all JavaScript files added with
     * $options['preprocess'] set to TRUE will be merged into one aggregate file.
     * Preprocessed inline JavaScript will not be aggregated into this single file.
     * Externally hosted JavaScripts are never aggregated.
     *
     * The reason for aggregating the files is outlined quite thoroughly here:
     * http://www.die.net/musings/page_load_time/ "Load fewer external objects. Due
     * to request overhead, one bigger file just loads faster than two smaller ones
     * half its size."
     *
     * $options['preprocess'] should be only set to TRUE when a file is required for
     * all typical visitors and most pages of a site. It is critical that all
     * preprocessed files are added unconditionally on every page, even if the
     * files are not needed on a page. This is normally done by calling
     * drupal_add_js() in a hook_init() implementation.
     *
     * Non-preprocessed files should only be added to the page when they are
     * actually needed.
     *
     * @param $data
     *   (optional) If given, the value depends on the $options parameter:
     *   - 'file': Path to the file relative to base_path().
     *   - 'inline': The JavaScript code that should be placed in the given scope.
     *   - 'external': The absolute path to an external JavaScript file that is not
     *     hosted on the local server. These files will not be aggregated if
     *     JavaScript aggregation is enabled.
     *   - 'setting': An associative array with configuration options. The array is
     *     merged directly into Drupal.settings. All modules should wrap their
     *     actual configuration settings in another variable to prevent conflicts in
     *     the Drupal.settings namespace. Items added with a string key will replace
     *     existing settings with that key; items with numeric array keys will be
     *     added to the existing settings array.
     * @param $options
     *   (optional) A string defining the type of JavaScript that is being added in
     *   the $data parameter ('file'/'setting'/'inline'/'external'), or an
     *   associative array. JavaScript settings should always pass the string
     *   'setting' only. Other types can have the following elements in the array:
     *   - type: The type of JavaScript that is to be added to the page. Allowed
     *     values are 'file', 'inline', 'external' or 'setting'. Defaults
     *     to 'file'.
     *   - scope: The location in which you want to place the script. Possible
     *     values are 'header' or 'footer'. If your theme implements different
     *     regions, you can also use these. Defaults to 'header'.
     *   - group: A number identifying the group in which to add the JavaScript.
     *     Available constants are:
     *     - JS_LIBRARY: Any libraries, settings, or jQuery plugins.
     *     - JS_DEFAULT: Any module-layer JavaScript.
     *     - JS_THEME: Any theme-layer JavaScript.
     *     The group number serves as a weight: JavaScript within a lower weight
     *     group is presented on the page before JavaScript within a higher weight
     *     group.
     *   - every_page: For optimal front-end performance when aggregation is
     *     enabled, this should be set to TRUE if the JavaScript is present on every
     *     page of the website for users for whom it is present at all. This
     *     defaults to FALSE. It is set to TRUE for JavaScript files that are added
     *     via module and theme .info files. Modules that add JavaScript within
     *     hook_init() implementations, or from other code that ensures that the
     *     JavaScript is added to all website pages, should also set this flag to
     *     TRUE. All JavaScript files within the same group and that have the
     *     'every_page' flag set to TRUE and do not have 'preprocess' set to FALSE
     *     are aggregated together into a single aggregate file, and that aggregate
     *     file can be reused across a user's entire site visit, leading to faster
     *     navigation between pages. However, JavaScript that is only needed on
     *     pages less frequently visited, can be added by code that only runs for
     *     those particular pages, and that code should not set the 'every_page'
     *     flag. This minimizes the size of the aggregate file that the user needs
     *     to download when first visiting the website. JavaScript without the
     *     'every_page' flag is aggregated into a separate aggregate file. This
     *     other aggregate file is likely to change from page to page, and each new
     *     aggregate file needs to be downloaded when first encountered, so it
     *     should be kept relatively small by ensuring that most commonly needed
     *     JavaScript is added to every page.
     *   - weight: A number defining the order in which the JavaScript is added to
     *     the page relative to other JavaScript with the same 'scope', 'group',
     *     and 'every_page' value. In some cases, the order in which the JavaScript
     *     is presented on the page is very important. jQuery, for example, must be
     *     added to the page before any jQuery code is run, so jquery.js uses the
     *     JS_LIBRARY group and a weight of -20, jquery.once.js (a library drupal.js
     *     depends on) uses the JS_LIBRARY group and a weight of -19, drupal.js uses
     *     the JS_LIBRARY group and a weight of -1, other libraries use the
     *     JS_LIBRARY group and a weight of 0 or higher, and all other scripts use
     *     one of the other group constants. The exact ordering of JavaScript is as
     *     follows:
     *     - First by scope, with 'header' first, 'footer' last, and any other
     *       scopes provided by a custom theme coming in between, as determined by
     *       the theme.
     *     - Then by group.
     *     - Then by the 'every_page' flag, with TRUE coming before FALSE.
     *     - Then by weight.
     *     - Then by the order in which the JavaScript was added. For example, all
     *       else being the same, JavaScript added by a call to drupal_add_js() that
     *       happened later in the page request gets added to the page after one for
     *       which drupal_add_js() happened earlier in the page request.
     *   - defer: If set to TRUE, the defer attribute is set on the &lt;script&gt;
     *     tag.  Defaults to FALSE.
     *   - cache: If set to FALSE, the JavaScript file is loaded anew on every page
     *     call; in other words, it is not cached. Used only when 'type' references
     *     a JavaScript file. Defaults to TRUE.
     *   - preprocess: If TRUE and JavaScript aggregation is enabled, the script
     *     file will be aggregated. Defaults to TRUE.
     *
     * @return
     *   The current array of JavaScript files, settings, and in-line code,
     *   including Drupal defaults, anything previously added with calls to
     *   drupal_add_js(), and this function call's additions.
     *
     * @see drupal_get_js()
     */
    function drupal_add_js($data = NULL, $options = NULL) {
      $javascript = &drupal_static(__FUNCTION__, array());
    
      // Construct the options, taking the defaults into consideration.
      if (isset($options)) {
        if (!is_array($options)) {
          $options = array('type' => $options);
        }
      }
      else {
        $options = array();
      }
      $options += drupal_js_defaults($data);
    
      // Preprocess can only be set if caching is enabled.
      $options['preprocess'] = $options['cache'] ? $options['preprocess'] : FALSE;
    
      // Tweak the weight so that files of the same weight are included in the
      // order of the calls to drupal_add_js().
      $options['weight'] += count($javascript) / 1000;
    
      if (isset($data)) {
        // Add jquery.js and drupal.js, as well as the basePath setting, the
        // first time a JavaScript file is added.
        if (empty($javascript)) {
          // url() generates the prefix using hook_url_outbound_alter(). Instead of
          // running the hook_url_outbound_alter() again here, extract the prefix
          // from url().
          url('', array('prefix' => &$prefix));
          $javascript = array(
            'settings' => array(
              'data' => array(
                array('basePath' => base_path()),
                array('pathPrefix' => empty($prefix) ? '' : $prefix),
              ),
              'type' => 'setting',
              'scope' => 'header',
              'group' => JS_LIBRARY,
              'every_page' => TRUE,
              'weight' => 0,
            ),
            'misc/drupal.js' => array(
              'data' => 'misc/drupal.js',
              'type' => 'file',
              'scope' => 'header',
              'group' => JS_LIBRARY,
              'every_page' => TRUE,
              'weight' => -1,
              'preprocess' => TRUE,
              'cache' => TRUE,
              'defer' => FALSE,
            ),
          );
          // Register all required libraries.
          drupal_add_library('system', 'jquery', TRUE);
          drupal_add_library('system', 'jquery.once', TRUE);
        }
    
        switch ($options['type']) {
          case 'setting':
            // All JavaScript settings are placed in the header of the page with
            // the library weight so that inline scripts appear afterwards.
            $javascript['settings']['data'][] = $data;
            break;
    
          case 'inline':
            $javascript[] = $options;
            break;
    
          default: // 'file' and 'external'
            // Local and external files must keep their name as the associative key
            // so the same JavaScript file is not added twice.
            $javascript[$options['data']] = $options;
        }
      }
      return $javascript;
    }
    
    /**
     * Constructs an array of the defaults that are used for JavaScript items.
     *
     * @param $data
     *   (optional) The default data parameter for the JavaScript item array.
     * @see drupal_get_js()
     * @see drupal_add_js()
     */
    function drupal_js_defaults($data = NULL) {
      return array(
        'type' => 'file',
        'group' => JS_DEFAULT,
        'every_page' => FALSE,
        'weight' => 0,
        'scope' => 'header',
        'cache' => TRUE,
        'defer' => FALSE,
        'preprocess' => TRUE,
        'version' => NULL,
        'data' => $data,
      );
    }
    
    /**
     * Returns a themed presentation of all JavaScript code for the current page.
     *
     * References to JavaScript files are placed in a certain order: first, all
     * 'core' files, then all 'module' and finally all 'theme' JavaScript files
     * are added to the page. Then, all settings are output, followed by 'inline'
     * JavaScript code. If running update.php, all preprocessing is disabled.
     *
     * Note that hook_js_alter(&$javascript) is called during this function call
     * to allow alterations of the JavaScript during its presentation. Calls to
     * drupal_add_js() from hook_js_alter() will not be added to the output
     * presentation. The correct way to add JavaScript during hook_js_alter()
     * is to add another element to the $javascript array, deriving from
     * drupal_js_defaults(). See locale_js_alter() for an example of this.
     *
     * @param $scope
     *   (optional) The scope for which the JavaScript rules should be returned.
     *   Defaults to 'header'.
     * @param $javascript
     *   (optional) An array with all JavaScript code. Defaults to the default
     *   JavaScript array for the given scope.
     * @param $skip_alter
     *   (optional) If set to TRUE, this function skips calling drupal_alter() on
     *   $javascript, useful when the calling function passes a $javascript array
     *   that has already been altered.
     * @return
     *   All JavaScript code segments and includes for the scope as HTML tags.
     * @see drupal_add_js()
     * @see locale_js_alter()
     * @see drupal_js_defaults()
     */
    function drupal_get_js($scope = 'header', $javascript = NULL, $skip_alter = FALSE) {
      if (!isset($javascript)) {
        $javascript = drupal_add_js();
      }
      if (empty($javascript)) {
        return '';
      }
    
      // Allow modules to alter the JavaScript.
      if (!$skip_alter) {
        drupal_alter('js', $javascript);
      }
    
      // Filter out elements of the given scope.
      $items = array();
      foreach ($javascript as $key => $item) {
        if ($item['scope'] == $scope) {
          $items[$key] = $item;
        }
      }
    
      $output = '';
      // The index counter is used to keep aggregated and non-aggregated files in
      // order by weight.
      $index = 1;
      $processed = array();
      $files = array();
      $preprocess_js = (variable_get('preprocess_js', FALSE) && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update'));
    
      // A dummy query-string is added to filenames, to gain control over
      // browser-caching. The string changes on every update or full cache
      // flush, forcing browsers to load a new copy of the files, as the
      // URL changed. Files that should not be cached (see drupal_add_js())
      // get REQUEST_TIME as query-string instead, to enforce reload on every
      // page request.
      $default_query_string = variable_get('css_js_query_string', '0');
    
      // For inline JavaScript to validate as XHTML, all JavaScript containing
      // XHTML needs to be wrapped in CDATA. To make that backwards compatible
      // with HTML 4, we need to comment out the CDATA-tag.
      $embed_prefix = "\n<!--//--><![CDATA[//><!--\n";
      $embed_suffix = "\n//--><!]]>\n";
    
      // Since JavaScript may look for arguments in the URL and act on them, some
      // third-party code might require the use of a different query string.
      $js_version_string = variable_get('drupal_js_version_query_string', 'v=');
    
      // Sort the JavaScript so that it appears in the correct order.
      uasort($items, 'drupal_sort_css_js');
    
      // Provide the page with information about the individual JavaScript files
      // used, information not otherwise available when aggregation is enabled.
      $setting['ajaxPageState']['js'] = array_fill_keys(array_keys($items), 1);
      unset($setting['ajaxPageState']['js']['settings']);
      drupal_add_js($setting, 'setting');
    
      // If we're outputting the header scope, then this might be the final time
      // that drupal_get_js() is running, so add the setting to this output as well
      // as to the drupal_add_js() cache. If $items['settings'] doesn't exist, it's
      // because drupal_get_js() was intentionally passed a $javascript argument
      // stripped off settings, potentially in order to override how settings get
      // output, so in this case, do not add the setting to this output.
      if ($scope == 'header' && isset($items['settings'])) {
        $items['settings']['data'][] = $setting;
      }
    
      // Loop through the JavaScript to construct the rendered output.
      $element = array(
        '#tag' => 'script',
        '#value' => '',
        '#attributes' => array(
          'type' => 'text/javascript',
        ),
      );
      foreach ($items as $item) {
        $query_string =  empty($item['version']) ? $default_query_string : $js_version_string . $item['version'];
    
        switch ($item['type']) {
          case 'setting':
            $js_element = $element;
            $js_element['#value_prefix'] = $embed_prefix;
            $js_element['#value'] = 'jQuery.extend(Drupal.settings, ' . drupal_json_encode(drupal_array_merge_deep_array($item['data'])) . ");";
            $js_element['#value_suffix'] = $embed_suffix;
            $output .= theme('html_tag', array('element' => $js_element));
            break;
    
          case 'inline':
            $js_element = $element;
            if ($item['defer']) {
              $js_element['#attributes']['defer'] = 'defer';
            }
            $js_element['#value_prefix'] = $embed_prefix;
            $js_element['#value'] = $item['data'];
            $js_element['#value_suffix'] = $embed_suffix;
            $processed[$index++] = theme('html_tag', array('element' => $js_element));
            break;
    
          case 'file':
            $js_element = $element;
            if (!$item['preprocess'] || !$preprocess_js) {
              if ($item['defer']) {
                $js_element['#attributes']['defer'] = 'defer';
              }
              $query_string_separator = (strpos($item['data'], '?') !== FALSE) ? '&' : '?';
              $js_element['#attributes']['src'] = file_create_url($item['data']) . $query_string_separator . ($item['cache'] ? $query_string : REQUEST_TIME);
              $processed[$index++] = theme('html_tag', array('element' => $js_element));
            }
            else {
              // By increasing the index for each aggregated file, we maintain
              // the relative ordering of JS by weight. We also set the key such
              // that groups are split by items sharing the same 'group' value and
              // 'every_page' flag. While this potentially results in more aggregate
              // files, it helps make each one more reusable across a site visit,
              // leading to better front-end performance of a website as a whole.
              // See drupal_add_js() for details.
              $key = 'aggregate_' . $item['group'] . '_' . $item['every_page'] . '_' . $index;
              $processed[$key] = '';
              $files[$key][$item['data']] = $item;
            }
            break;
    
          case 'external':
            $js_element = $element;
            // Preprocessing for external JavaScript files is ignored.
            if ($item['defer']) {
              $js_element['#attributes']['defer'] = 'defer';
            }
            $js_element['#attributes']['src'] = $item['data'];
            $processed[$index++] = theme('html_tag', array('element' => $js_element));
            break;
        }
      }
    
      // Aggregate any remaining JS files that haven't already been output.
      if ($preprocess_js && count($files) > 0) {
        foreach ($files as $key => $file_set) {
          $uri = drupal_build_js_cache($file_set);
          // Only include the file if was written successfully. Errors are logged
          // using watchdog.
          if ($uri) {
            $preprocess_file = file_create_url($uri);
            $js_element = $element;
            $js_element['#attributes']['src'] = $preprocess_file;
            $processed[$key] = theme('html_tag', array('element' => $js_element));
          }
        }
      }
    
      // Keep the order of JS files consistent as some are preprocessed and others are not.
      // Make sure any inline or JS setting variables appear last after libraries have loaded.
      return implode('', $processed) . $output;
    }
    
    /**
     * Adds attachments to a render() structure.
     *
     * Libraries, JavaScript, CSS and other types of custom structures are attached
     * to elements using the #attached property. The #attached property is an
     * associative array, where the keys are the the attachment types and the values
     * are the attached data. For example:
     * @code
     * $build['#attached'] = array(
     *   'js' => array(drupal_get_path('module', 'taxonomy') . '/taxonomy.js'),
     *   'css' => array(drupal_get_path('module', 'taxonomy') . '/taxonomy.css'),
     * );
     * @endcode
     *
     * 'js', 'css', and 'library' are types that get special handling.  For any
     * other kind of attached data, the array key must be the full name of the
     * callback function and each value an array of arguments. For example:
     * @code
     * $build['#attached']['drupal_add_http_header'] = array(
     *   array('Content-Type', 'application/rss+xml; charset=utf-8'),
     * );
     * @endcode
     *
     * External 'js' and 'css' files can also be loaded. For example:
     * @code
     * $build['#attached']['js'] = array(
     *   'http://code.jquery.com/jquery-1.4.2.min.js' => array(
     *     'type' => 'external',
     *   ),
     * );
     * @endcode
     *
     * @param $elements
     *   The structured array describing the data being rendered.
     * @param $group
     *   The default group of JavaScript and CSS being added. This is only applied
     *   to the stylesheets and JavaScript items that don't have an explicit group
     *   assigned to them.
     * @param $dependency_check
     *   When TRUE, will exit if a given library's dependencies are missing. When
     *   set to FALSE, will continue to add the libraries, even though one or more
     *   dependencies are missing. Defaults to FALSE.
     * @param $every_page
     *   Set to TRUE to indicate that the attachments are added to every page on the
     *   site. Only attachments with the every_page flag set to TRUE can participate
     *   in JavaScript/CSS aggregation.
     *
     * @return
     *   FALSE if there were any missing library dependencies; TRUE if all library
     *   dependencies were met.
     *
     * @see drupal_add_library()
     * @see drupal_add_js()
     * @see drupal_add_css()
     * @see drupal_render()
     */
    function drupal_process_attached($elements, $group = JS_DEFAULT, $dependency_check = FALSE, $every_page = NULL) {
      // Add defaults to the special attached structures that should be processed differently.
      $elements['#attached'] += array(
        'library' => array(),
        'js' => array(),
        'css' => array(),
      );
    
      // Add the libraries first.
      $success = TRUE;
      foreach ($elements['#attached']['library'] as $library) {
        if (drupal_add_library($library[0], $library[1], $every_page) === FALSE) {
          $success = FALSE;
          // Exit if the dependency is missing.
          if ($dependency_check) {
            return $success;
          }
        }
      }
      unset($elements['#attached']['library']);
    
      // Add both the JavaScript and the CSS.
      // The parameters for drupal_add_js() and drupal_add_css() require special
      // handling.
      foreach (array('js', 'css') as $type) {
        foreach ($elements['#attached'][$type] as $data => $options) {
          // If the value is not an array, it's a filename and passed as first
          // (and only) argument.
          if (!is_array($options)) {
            $data = $options;
            $options = NULL;
          }
          // In some cases, the first parameter ($data) is an array. Arrays can't be
          // passed as keys in PHP, so we have to get $data from the value array.
          if (is_numeric($data)) {
            $data = $options['data'];
            unset($options['data']);
          }
          // Apply the default group if it isn't explicitly given.
          if (!isset($options['group'])) {
            $options['group'] = $group;
          }
          // Set the every_page flag if one was passed.
          if (isset($every_page)) {
            $options['every_page'] = $every_page;
          }
          call_user_func('drupal_add_' . $type, $data, $options);
        }
        unset($elements['#attached'][$type]);
      }
    
      // Add additional types of attachments specified in the render() structure.
      // Libraries, JavaScript and CSS have been added already, as they require
      // special handling.
      foreach ($elements['#attached'] as $callback => $options) {
        if (function_exists($callback)) {
          foreach ($elements['#attached'][$callback] as $args) {
            call_user_func_array($callback, $args);
          }
        }
      }
    
      return $success;
    }
    
    /**
     * Adds JavaScript to change the state of an element based on another element.
     *
     * 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),
     *     ),
     *   ),
     * );
     * @endcode
     *
     * The following states may be applied to an element:
     * - enabled
     * - disabled
     * - visible
     * - invisible
     * - checked
     * - unchecked
     * - expanded
     * - collapsed
     *
     * The following states may be used in remote conditions:
     * - enabled
     * - disabled
     * - visible
     * - invisible
     * - checked
     * - unchecked
     * - value
     *
     * The following states exist for both states and remote conditions, but are not
     * fully implemented and may not change anything on the element:
     * - required
     * - optional
     * - relevant
     * - irrelevant
     * - valid
     * - invalid
     * - touched
     * - untouched
     * - filled
     * - empty
     * - 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 $elements
     *   A renderable array element having a #states property as described above.
     *
     * @see form_example_states_form()
     */
    function drupal_process_states(&$elements) {
      $elements['#attached']['library'][] = array('system', 'drupal.states');
      $elements['#attached']['js'][] = array(
        'type' => 'setting',
        'data' => array('states' => array('#' . $elements['#id'] => $elements['#states'])),
      );
    }
    
    /**
     * Adds multiple JavaScript or CSS files at the same time.
     *
     * A library defines a set of JavaScript and/or CSS files, optionally using
     * settings, and optionally requiring another library. For example, a library
     * can be a jQuery plugin, a JavaScript framework, or a CSS framework. This
     * function allows modules to load a library defined/shipped by itself or a
     * depending module, without having to add all files of the library separately.
     * Each library is only loaded once.
     *
     * @param $module
     *   The name of the module that registered the library.
     * @param $name
     *   The name of the library to add.
     * @param $every_page
     *   Set to TRUE if this library is added to every page on the site. Only items
     *   with the every_page flag set to TRUE can participate in aggregation.
     *
     * @return
     *   TRUE if the library was successfully added; FALSE if the library or one of
     *   its dependencies could not be added.
     *
     * @see drupal_get_library()
     * @see hook_library()
     * @see hook_library_alter()
     */
    function drupal_add_library($module, $name, $every_page = NULL) {
      $added = &drupal_static(__FUNCTION__, array());
    
      // Only process the library if it exists and it was not added already.
      if (!isset($added[$module][$name])) {
        if ($library = drupal_get_library($module, $name)) {
          // Add all components within the library.
          $elements['#attached'] = array(
            'library' => $library['dependencies'],
            'js' => $library['js'],
            'css' => $library['css'],
          );
          $added[$module][$name] = drupal_process_attached($elements, JS_LIBRARY, TRUE, $every_page);
        }
        else {
          // Requested library does not exist.
          $added[$module][$name] = FALSE;
        }
      }
    
      return $added[$module][$name];
    }
    
    /**
     * Retrieves information for a JavaScript/CSS library.
     *
     * Library information is statically cached. Libraries are keyed by module for
     * several reasons:
     * - Libraries are not unique. Multiple modules might ship with the same library
     *   in a different version or variant. This registry cannot (and does not
     *   attempt to) prevent library conflicts.
     * - Modules implementing and thereby depending on a library that is registered
     *   by another module can only rely on that module's library.
     * - Two (or more) modules can still register the same library and use it
     *   without conflicts in case the libraries are loaded on certain pages only.
     *
     * @param $module
     *   The name of a module that registered a library.
     * @param $name
     *   (optional) The name of a registered library to retrieve. By default, all
     *   libraries registered by $module are returned.
     *
     * @return
     *   The definition of the requested library, if $name was passed and it exists,
     *   or FALSE if it does not exist. If no $name was passed, an associative array
     *   of libraries registered by $module is returned (which may be empty).
     *
     * @see drupal_add_library()
     * @see hook_library()
     * @see hook_library_alter()
     *
     * @todo The purpose of drupal_get_*() is completely different to other page
     *   requisite API functions; find and use a different name.
     */
    function drupal_get_library($module, $name = NULL) {
      $libraries = &drupal_static(__FUNCTION__, array());
    
      if (!isset($libraries[$module])) {
        // Retrieve all libraries associated with the module.
        $module_libraries = module_invoke($module, 'library');
        if (empty($module_libraries)) {
          $module_libraries = array();
        }
        // Allow modules to alter the module's registered libraries.
        drupal_alter('library', $module_libraries, $module);
    
        foreach ($module_libraries as $key => $data) {
          if (is_array($data)) {
            // Add default elements to allow for easier processing.
            $module_libraries[$key] += array('dependencies' => array(), 'js' => array(), 'css' => array());
            foreach ($module_libraries[$key]['js'] as $file => $options) {
              $module_libraries[$key]['js'][$file]['version'] = $module_libraries[$key]['version'];
            }
          }
        }
        $libraries[$module] = $module_libraries;
      }
      if (isset($name)) {
        if (!isset($libraries[$module][$name])) {
          $libraries[$module][$name] = FALSE;
        }
        return $libraries[$module][$name];
      }
      return $libraries[$module];
    }
    
    /**
     * Assist in adding the tableDrag JavaScript behavior to a themed table.
     *
     * Draggable tables should be used wherever an outline or list of sortable items
     * needs to be arranged by an end-user. Draggable tables are very flexible and
     * can manipulate the value of form elements placed within individual columns.
     *
     * To set up a table to use drag and drop in place of weight select-lists or
     * in place of a form that contains parent relationships, the form must be
     * themed into a table. The table must have an id attribute set. If using
     * theme_table(), the id may be set as such:
     * @code
     * $output = theme('table', array('header' => $header, 'rows' => $rows, 'attributes' => array('id' => 'my-module-table')));
     * return $output;
     * @endcode
     *
     * In the theme function for the form, a special class must be added to each
     * form element within the same column, "grouping" them together.
     *
     * In a situation where a single weight column is being sorted in the table, the
     * classes could be added like this (in the theme function):
     * @code
     * $form['my_elements'][$delta]['weight']['#attributes']['class'] = array('my-elements-weight');
     * @endcode
     *
     * Each row of the table must also have a class of "draggable" in order to enable the
     * drag handles:
     * @code
     * $row = array(...);
     * $rows[] = array(
     *   'data' => $row,
     *   'class' => array('draggable'),
     * );
     * @endcode
     *
     * When tree relationships are present, the two additional classes
     * 'tabledrag-leaf' and 'tabledrag-root' can be used to refine the behavior:
     * - Rows with the 'tabledrag-leaf' class cannot have child rows.
     * - Rows with the 'tabledrag-root' class cannot be nested under a parent row.
     *
     * Calling drupal_add_tabledrag() would then be written as such:
     * @code
     * drupal_add_tabledrag('my-module-table', 'order', 'sibling', 'my-elements-weight');
     * @endcode
     *
     * In a more complex case where there are several groups in one column (such as
     * the block regions on the admin/structure/block page), a separate subgroup class
     * must also be added to differentiate the groups.
     * @code
     * $form['my_elements'][$region][$delta]['weight']['#attributes']['class'] = array('my-elements-weight', 'my-elements-weight-' . $region);
     * @endcode
     *
     * $group is still 'my-element-weight', and the additional $subgroup variable
     * will be passed in as 'my-elements-weight-' . $region. This also means that
     * you'll need to call drupal_add_tabledrag() once for every region added.
     *
     * @code
     * foreach ($regions as $region) {
     *   drupal_add_tabledrag('my-module-table', 'order', 'sibling', 'my-elements-weight', 'my-elements-weight-' . $region);
     * }
     * @endcode
     *
     * In a situation where tree relationships are present, adding multiple
     * subgroups is not necessary, because the table will contain indentations that
     * provide enough information about the sibling and parent relationships.
     * See theme_menu_overview_form() for an example creating a table containing
     * parent relationships.
     *
     * Please note that this function should be called from the theme layer, such as
     * in a .tpl.php file, theme_ function, or in a template_preprocess function,
     * not in a form declaration. Though the same JavaScript could be added to the
     * page using drupal_add_js() directly, this function helps keep template files
     * clean and readable. It also prevents tabledrag.js from being added twice
     * accidentally.
     *
     * @param $table_id
     *   String containing the target table's id attribute. If the table does not
     *   have an id, one will need to be set, such as <table id="my-module-table">.
     * @param $action
     *   String describing the action to be done on the form item. Either 'match'
     *   'depth', or 'order'. Match is typically used for parent relationships.
     *   Order is typically used to set weights on other form elements with the same
     *   group. Depth updates the target element with the current indentation.
     * @param $relationship
     *   String describing where the $action variable should be performed. Either
     *   'parent', 'sibling', 'group', or 'self'. Parent will only look for fields
     *   up the tree. Sibling will look for fields in the same group in rows above
     *   and below it. Self affects the dragged row itself. Group affects the
     *   dragged row, plus any children below it (the entire dragged group).
     * @param $group
     *   A class name applied on all related form elements for this action.
     * @param $subgroup
     *   (optional) If the group has several subgroups within it, this string should
     *   contain the class name identifying fields in the same subgroup.
     * @param $source
     *   (optional) If the $action is 'match', this string should contain the class
     *   name identifying what field will be used as the source value when matching
     *   the value in $subgroup.
     * @param $hidden
     *   (optional) The column containing the field elements may be entirely hidden
     *   from view dynamically when the JavaScript is loaded. Set to FALSE if the
     *   column should not be hidden.
     * @param $limit
     *   (optional) Limit the maximum amount of parenting in this table.
     * @see block-admin-display-form.tpl.php
     * @see theme_menu_overview_form()
     */
    function drupal_add_tabledrag($table_id, $action, $relationship, $group, $subgroup = NULL, $source = NULL, $hidden = TRUE, $limit = 0) {
      $js_added = &drupal_static(__FUNCTION__, FALSE);
      if (!$js_added) {
        // Add the table drag JavaScript to the page before the module JavaScript
        // to ensure that table drag behaviors are registered before any module
        // uses it.
        drupal_add_library('system', 'jquery.cookie');
        drupal_add_js('misc/tabledrag.js', array('weight' => -1));
        $js_added = TRUE;
      }
    
      // If a subgroup or source isn't set, assume it is the same as the group.
      $target = isset($subgroup) ? $subgroup : $group;
      $source = isset($source) ? $source : $target;
      $settings['tableDrag'][$table_id][$group][] = array(
        'target' => $target,
        'source' => $source,
        'relationship' => $relationship,
        'action' => $action,
        'hidden' => $hidden,
        'limit' => $limit,
      );
      drupal_add_js($settings, 'setting');
    }
    
    /**
     * Aggregates JavaScript files into a cache file in the files directory.
     *
     * The file name for the JavaScript cache file is generated from the hash of
     * the aggregated contents of the files in $files. This forces proxies and
     * browsers to download new JavaScript when the JavaScript changes.
     *
     * The cache file name is retrieved on a page load via a lookup variable that
     * contains an associative array. The array key is the hash of the names in
     * $files while the value is the cache file name. The cache file is generated
     * in two cases. First, if there is no file name value for the key, which will
     * happen if a new file name has been added to $files or after the lookup
     * variable is emptied to force a rebuild of the cache.  Second, the cache
     * file is generated if it is missing on disk. Old cache files are not deleted
     * immediately when the lookup variable is emptied, but are deleted after a set
     * period by drupal_delete_file_if_stale(). This ensures that files referenced
     * by a cached page will still be available.
     *
     * @param $files
     *   An array of JavaScript files to aggregate and compress into one file.
     *
     * @return
     *   The URI of the cache file, or FALSE if the file could not be saved.
     */
    function drupal_build_js_cache($files) {
      $contents = '';
      $uri = '';
      $map = variable_get('drupal_js_cache_files', array());
      $key = hash('sha256', serialize($files));
      if (isset($map[$key])) {
        $uri = $map[$key];
      }
    
      if (empty($uri) || !file_exists($uri)) {
        // Build aggregate JS file.
        foreach ($files as $path => $info) {
          if ($info['preprocess']) {
            // Append a ';' and a newline after each JS file to prevent them from running together.
            $contents .= file_get_contents($path) . ";\n";
          }
        }
        // Prefix filename to prevent blocking by firewalls which reject files
        // starting with "ad*".
        $filename = 'js_' . drupal_hash_base64($contents) . '.js';
        // Create the js/ within the files folder.
        $jspath = 'public://js';
        $uri = $jspath . '/' . $filename;
        // Create the JS file.
        file_prepare_directory($jspath, FILE_CREATE_DIRECTORY);
        if (!file_exists($uri) && !file_unmanaged_save_data($contents, $uri, FILE_EXISTS_REPLACE)) {
          return FALSE;
        }
        // If JS gzip compression is enabled, clean URLs are enabled (which means
        // that rewrite rules are working) and the zlib extension is available then
        // create a gzipped version of this file. This file is served conditionally
        // to browsers that accept gzip using .htaccess rules.
        if (variable_get('js_gzip_compression', TRUE) && variable_get('clean_url', 0) && extension_loaded('zlib')) {
          if (!file_exists($uri . '.gz') && !file_unmanaged_save_data(gzencode($contents, 9, FORCE_GZIP), $uri . '.gz', FILE_EXISTS_REPLACE)) {
            return FALSE;
          }
        }
        $map[$key] = $uri;
        variable_set('drupal_js_cache_files', $map);
      }
      return $uri;
    }
    
    /**
     * Deletes old cached JavaScript files and variables.
     */
    function drupal_clear_js_cache() {
      variable_del('javascript_parsed');
      variable_del('drupal_js_cache_files');
      file_scan_directory('public://js', '/.*/', array('callback' => 'drupal_delete_file_if_stale'));
    }
    
    /**
     * Converts a PHP variable into its JavaScript equivalent.
     *
     * We use HTML-safe strings, i.e. with <, > and & escaped.
     *
     * @see drupal_json_decode()
     * @ingroup php_wrappers
     */
    function drupal_json_encode($var) {
      // json_encode() does not escape <, > and &, so we do it with str_replace().
      return str_replace(array('<', '>', '&'), array('\u003c', '\u003e', '\u0026'), json_encode($var));
    }
    
    /**
     * Converts an HTML-safe JSON string into its PHP equivalent.
     *
     * @see drupal_json_encode()
     * @ingroup php_wrappers
     */
    function drupal_json_decode($var) {
      return json_decode($var, TRUE);
    }
    
    /**
     * Return data in JSON format.
     *
     * This function should be used for JavaScript callback functions returning
     * data in JSON format. It sets the header for JavaScript output.
     *
     * @param $var
     *   (optional) If set, the variable will be converted to JSON and output.
     */
    function drupal_json_output($var = NULL) {
      // We are returning JSON, so tell the browser.
      drupal_add_http_header('Content-Type', 'application/json');
    
      if (isset($var)) {
        echo drupal_json_encode($var);
      }
    }
    
    /**
     * Get a salt useful for hardening against SQL injection.
     *
     * @return
     *   A salt based on information in settings.php, not in the database.
     */
    function drupal_get_hash_salt() {
      global $drupal_hash_salt, $databases;
      // If the $drupal_hash_salt variable is empty, a hash of the serialized
      // database credentials is used as a fallback salt.
      return empty($drupal_hash_salt) ? hash('sha256', serialize($databases)) : $drupal_hash_salt;
    }
    
    /**
     * Ensure the private key variable used to generate tokens is set.
     *
     * @return
     *   The private key.
     */
    function drupal_get_private_key() {
      if (!($key = variable_get('drupal_private_key', 0))) {
        $key = drupal_hash_base64(drupal_random_bytes(55));
        variable_set('drupal_private_key', $key);
      }
      return $key;
    }
    
    /**
     * Generate a token based on $value, the current user session and private key.
     *
     * @param $value
     *   An additional value to base the token on.
     */
    function drupal_get_token($value = '') {
      return drupal_hmac_base64($value, session_id() . drupal_get_private_key() . drupal_get_hash_salt());
    }
    
    /**
     * Validate a token based on $value, the current user session and private key.
     *
     * @param $token
     *   The token to be validated.
     * @param $value
     *   An additional value to base the token on.
     * @param $skip_anonymous
     *   Set to true to skip token validation for anonymous users.
     * @return
     *   True for a valid token, false for an invalid token. When $skip_anonymous
     *   is true, the return value will always be true for anonymous users.
     */
    function drupal_valid_token($token, $value = '', $skip_anonymous = FALSE) {
      global $user;
      return (($skip_anonymous && $user->uid == 0) || ($token == drupal_get_token($value)));
    }
    
    function _drupal_bootstrap_full() {
      static $called = FALSE;
    
      if ($called) {
        return;
      }
      $called = TRUE;
      require_once DRUPAL_ROOT . '/' . variable_get('path_inc', 'includes/path.inc');
      require_once DRUPAL_ROOT . '/includes/theme.inc';
      require_once DRUPAL_ROOT . '/includes/pager.inc';
      require_once DRUPAL_ROOT . '/' . variable_get('menu_inc', 'includes/menu.inc');
      require_once DRUPAL_ROOT . '/includes/tablesort.inc';
      require_once DRUPAL_ROOT . '/includes/file.inc';
      require_once DRUPAL_ROOT . '/includes/unicode.inc';
      require_once DRUPAL_ROOT . '/includes/image.inc';
      require_once DRUPAL_ROOT . '/includes/form.inc';
      require_once DRUPAL_ROOT . '/includes/mail.inc';
      require_once DRUPAL_ROOT . '/includes/actions.inc';
      require_once DRUPAL_ROOT . '/includes/ajax.inc';
      require_once DRUPAL_ROOT . '/includes/token.inc';
      require_once DRUPAL_ROOT . '/includes/errors.inc';
    
      // Detect string handling method
      unicode_check();
      // Undo magic quotes
      fix_gpc_magic();
      // Load all enabled modules
      module_load_all();
      // Make sure all stream wrappers are registered.
      file_get_stream_wrappers();
    
      $test_info = &$GLOBALS['drupal_test_info'];
      if (!empty($test_info['in_child_site'])) {
        // Running inside the simpletest child site, log fatal errors to test
        // specific file directory.
        ini_set('log_errors', 1);
        ini_set('error_log', 'public://error.log');
      }
    
      // Initialize $_GET['q'] prior to invoking hook_init().
      drupal_path_initialize();
    
      // Let all modules take action before the menu system handles the request.
      // We do not want this while running update.php.
      if (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update') {
        // Prior to invoking hook_init(), initialize the theme (potentially a custom
        // one for this page), so that:
        // - Modules with hook_init() implementations that call theme() or
        //   theme_get_registry() don't initialize the incorrect theme.
        // - The theme can have hook_*_alter() implementations affect page building
        //   (e.g., hook_form_alter(), hook_node_view_alter(), hook_page_alter()),
        //   ahead of when rendering starts.
        menu_set_custom_theme();
        drupal_theme_initialize();
        module_invoke_all('init');
      }
    }
    
    /**
     * Store the current page in the cache.
     *
     * If page_compression is enabled, a gzipped version of the page is stored in
     * the cache to avoid compressing the output on each request. The cache entry
     * is unzipped in the relatively rare event that the page is requested by a
     * client without gzip support.
     *
     * Page compression requires the PHP zlib extension
     * (http://php.net/manual/en/ref.zlib.php).
     *
     * @see drupal_page_header()
     */
    function drupal_page_set_cache() {
      global $base_root;
    
      if (drupal_page_is_cacheable()) {
        $cache = (object) array(
          'cid' => $base_root . request_uri(),
          'data' => array(
            'path' => $_GET['q'],
            'body' => ob_get_clean(),
            'title' => drupal_get_title(),
            'headers' => array(),
          ),
          'expire' => CACHE_TEMPORARY,
          'created' => REQUEST_TIME,
        );
    
        // Restore preferred header names based on the lower-case names returned
        // by drupal_get_http_header().
        $header_names = _drupal_set_preferred_header_name();
        foreach (drupal_get_http_header() as $name_lower => $value) {
          $cache->data['headers'][$header_names[$name_lower]] = $value;
          if ($name_lower == 'expires') {
            // Use the actual timestamp from an Expires header if available.
            $cache->expire = strtotime($value);
          }
        }
    
        if ($cache->data['body']) {
          if (variable_get('page_compression', TRUE) && extension_loaded('zlib')) {
            $cache->data['body'] = gzencode($cache->data['body'], 9, FORCE_GZIP);
          }
          cache_set($cache->cid, $cache->data, 'cache_page', $cache->expire);
        }
        return $cache;
      }
    }
    
    /**
     * Executes a cron run when called.
     *
     * Do not call this function from test, use $this->cronRun() instead.
     *
     * @return
     *   Returns TRUE if ran successfully
     */
    function drupal_cron_run() {
      // Allow execution to continue even if the request gets canceled.
      @ignore_user_abort(TRUE);
    
      // Prevent session information from being saved while cron is running.
      drupal_save_session(FALSE);
    
      // Force the current user to anonymous to ensure consistent permissions on
      // cron runs.
      $original_user = $GLOBALS['user'];
      $GLOBALS['user'] = drupal_anonymous_user();
    
      // Try to allocate enough time to run all the hook_cron implementations.
      drupal_set_time_limit(240);
    
      $return = FALSE;
      // Grab the defined cron queues.
      $queues = module_invoke_all('cron_queue_info');
      drupal_alter('cron_queue_info', $queues);
    
      // Try to acquire cron lock.
      if (!lock_acquire('cron', 240.0)) {
        // Cron is still running normally.
        watchdog('cron', 'Attempting to re-run cron while it is already running.', array(), WATCHDOG_WARNING);
      }
      else {
        // Make sure every queue exists. There is no harm in trying to recreate an
        // existing queue.
        foreach ($queues as $queue_name => $info) {
          DrupalQueue::get($queue_name)->createQueue();
        }
        // Register shutdown callback
        drupal_register_shutdown_function('drupal_cron_cleanup');
    
        // Iterate through the modules calling their cron handlers (if any):
        module_invoke_all('cron');
    
        // Record cron time
        variable_set('cron_last', REQUEST_TIME);
        watchdog('cron', 'Cron run completed.', array(), WATCHDOG_NOTICE);
    
        // Release cron lock.
        lock_release('cron');
    
        // Return TRUE so other functions can check if it did run successfully
        $return = TRUE;
      }
    
      foreach ($queues as $queue_name => $info) {
        $function = $info['worker callback'];
        $end = time() + (isset($info['time']) ? $info['time'] : 15);
        $queue = DrupalQueue::get($queue_name);
        while (time() < $end && ($item = $queue->claimItem())) {
          $function($item->data);
          $queue->deleteItem($item);
        }
      }
      // Restore the user.
      $GLOBALS['user'] = $original_user;
      drupal_save_session(TRUE);
    
      return $return;
    }
    
    /**
     * Shutdown function for cron cleanup.
     */
    function drupal_cron_cleanup() {
      // See if the semaphore is still locked.
      if (variable_get('cron_semaphore', FALSE)) {
        watchdog('cron', 'Cron run exceeded the time limit and was aborted.', array(), WATCHDOG_WARNING);
    
        // Release cron semaphore
        variable_del('cron_semaphore');
      }
    }
    
    /**
     * Returns information about system object files (modules, themes, etc.).
     *
     * This function is used to find all or some system object files (module files,
     * theme files, etc.) that exist on the site. It searches in several locations,
     * depending on what type of object you are looking for. For instance, if you
     * are looking for modules and call:
     * @code
     * drupal_system_listing("/\.module$/", "modules", 'name', 0);
     * @endcode
     * this function will search the site-wide modules directory (i.e., /modules/),
     * your install profile's directory (i.e.,
     * /profiles/your_site_profile/modules/), the all-sites directory (i.e.,
     * /sites/all/modules/), and your site-specific directory (i.e.,
     * /sites/your_site_dir/modules/), in that order, and return information about
     * all of the files ending in .module in those directories.
     *
     * The information is returned in an associative array, which can be keyed on
     * the file name ($key = 'filename'), the file name without the extension ($key
     * = 'name'), or the full file stream URI ($key = 'uri'). If you use a key of
     * 'filename' or 'name', files found later in the search will take precedence
     * over files found earlier (unless they belong to a module or theme not
     * compatible with Drupal core); if you choose a key of 'uri', you will get all
     * files found.
     *
     * @param string $mask
     *   The preg_match() regular expression for the files to find.
     * @param string $directory
     *   The subdirectory name in which the files are found. For example,
     *   'modules' will search in sub-directories of the top-level /modules
     *   directory, sub-directories of /sites/all/modules/, etc.
     * @param string $key
     *   The key to be used for the associative array returned. Possible values are
     *   'uri', for the file's URI; 'filename', for the basename of the file; and
     *   'name' for the name of the file without the extension. If you choose 'name'
     *   or 'filename', only the highest-precedence file will be returned.
     * @param int $min_depth
     *   Minimum depth of directories to return files from, relative to each
     *   directory searched. For instance, a minimum depth of 2 would find modules
     *   inside /modules/node/tests, but not modules directly in /modules/node.
     *
     * @return array
     *   An associative array of file objects, keyed on the chosen key. Each element
     *   in the array is an object containing file information, with properties:
     *   - 'uri': Full URI of the file.
     *   - 'filename': File name.
     *   - 'name': Name of file without the extension.
     */
    function drupal_system_listing($mask, $directory, $key = 'name', $min_depth = 1) {
      $config = conf_path();
    
      $profile = drupal_get_profile();
    
      $searchdir = array($directory);
      $files = array();
    
      // The 'profiles' directory contains pristine collections of modules and
      // themes as organized by a distribution. It is pristine in the same way
      // that /modules is pristine for core; users should avoid changing anything
      // there in favor of sites/all or sites/<domain> directories.
      if (file_exists("profiles/$profile/$directory")) {
        $searchdir[] = "profiles/$profile/$directory";
      }
    
      // Always search sites/all/* as well as the global directories
      $searchdir[] = 'sites/all/' . $directory;
    
      if (file_exists("$config/$directory")) {
        $searchdir[] = "$config/$directory";
      }
    
      // Get current list of items
      if (!function_exists('file_scan_directory')) {
        require_once DRUPAL_ROOT . '/includes/file.inc';
      }
      foreach ($searchdir as $dir) {
        $files_to_add = file_scan_directory($dir, $mask, array('key' => $key, 'min_depth' => $min_depth));
    
        // Duplicate files found in later search directories take precedence over
        // earlier ones, so we want them to overwrite keys in our resulting
        // $files array.
        // The exception to this is if the later file is from a module or theme not
        // compatible with Drupal core. This may occur during upgrades of Drupal
        // core when new modules exist in core while older contrib modules with the
        // same name exist in a directory such as sites/all/modules/.
        foreach (array_intersect_key($files_to_add, $files) as $file_key => $file) {
          // If it has no info file, then we just behave liberally and accept the
          // new resource on the list for merging.
          if (file_exists($info_file = dirname($file->uri) . '/' . $file->name . '.info')) {
            // Get the .info file for the module or theme this file belongs to.
            $info = drupal_parse_info_file($info_file);
    
            // If the module or theme is incompatible with Drupal core, remove it
            // from the array for the current search directory, so it is not
            // overwritten when merged with the $files array.
            if (isset($info['core']) && $info['core'] != DRUPAL_CORE_COMPATIBILITY) {
              unset($files_to_add[$file_key]);
            }
          }
        }
        $files = array_merge($files, $files_to_add);
      }
    
      return $files;
    }
    
    /**
     * Set the main page content value for later use.
     *
     * Given the nature of the Drupal page handling, this will be called once with
     * a string or array. We store that and return it later as the block is being
     * displayed.
     *
     * @param $content
     *   A string or renderable array representing the body of the page.
     * @return
     *   If called without $content, a renderable array representing the body of
     *   the page.
     */
    function drupal_set_page_content($content = NULL) {
      $content_block = &drupal_static(__FUNCTION__, NULL);
      $main_content_display = &drupal_static('system_main_content_added', FALSE);
    
      if (!empty($content)) {
        $content_block = (is_array($content) ? $content : array('main' => array('#markup' => $content)));
      }
      else {
        // Indicate that the main content has been requested. We assume that
        // the module requesting the content will be adding it to the page.
        // A module can indicate that it does not handle the content by setting
        // the static variable back to FALSE after calling this function.
        $main_content_display = TRUE;
        return $content_block;
      }
    }
    
    /**
     * #pre_render callback to render #browsers into #prefix and #suffix.
     *
     * @param $elements
     *   A render array with a '#browsers' property. The '#browsers' property can
     *   contain any or all of the following keys:
     *   - 'IE': If FALSE, the element is not rendered by Internet Explorer. If
     *     TRUE, the element is rendered by Internet Explorer. Can also be a string
     *     containing an expression for Internet Explorer to evaluate as part of a
     *     conditional comment. For example, this can be set to 'lt IE 7' for the
     *     element to be rendered in Internet Explorer 6, but not in Internet
     *     Explorer 7 or higher. Defaults to TRUE.
     *   - '!IE': If FALSE, the element is not rendered by browsers other than
     *     Internet Explorer. If TRUE, the element is rendered by those browsers.
     *     Defaults to TRUE.
     *   Examples:
     *   - To render an element in all browsers, '#browsers' can be left out or set
     *     to array('IE' => TRUE, '!IE' => TRUE).
     *   - To render an element in Internet Explorer only, '#browsers' can be set
     *     to array('!IE' => FALSE).
     *   - To render an element in Internet Explorer 6 only, '#browsers' can be set
     *     to array('IE' => 'lt IE 7', '!IE' => FALSE).
     *   - To render an element in Internet Explorer 8 and higher and in all other
     *     browsers, '#browsers' can be set to array('IE' => 'gte IE 8').
     *
     * @return
     *   The passed-in element with markup for conditional comments potentially
     *   added to '#prefix' and '#suffix'.
     */
    function drupal_pre_render_conditional_comments($elements) {
      $browsers = isset($elements['#browsers']) ? $elements['#browsers'] : array();
      $browsers += array(
        'IE' => TRUE,
        '!IE' => TRUE,
      );
    
      // If rendering in all browsers, no need for conditional comments.
      if ($browsers['IE'] === TRUE && $browsers['!IE']) {
        return $elements;
      }
    
      // Determine the conditional comment expression for Internet Explorer to
      // evaluate.
      if ($browsers['IE'] === TRUE) {
        $expression = 'IE';
      }
      elseif ($browsers['IE'] === FALSE) {
        $expression = '!IE';
      }
      else {
        $expression = $browsers['IE'];
      }
    
      // Wrap the element's potentially existing #prefix and #suffix properties with
      // conditional comment markup. The conditional comment expression is evaluated
      // by Internet Explorer only. To control the rendering by other browsers,
      // either the "downlevel-hidden" or "downlevel-revealed" technique must be
      // used. See http://en.wikipedia.org/wiki/Conditional_comment for details.
      $elements += array(
        '#prefix' => '',
        '#suffix' => '',
      );
      if (!$browsers['!IE']) {
        // "downlevel-hidden".
        $elements['#prefix'] = "\n<!--[if $expression]>\n" . $elements['#prefix'];
        $elements['#suffix'] .= "<![endif]-->\n";
      }
      else {
        // "downlevel-revealed".
        $elements['#prefix'] = "\n<!--[if $expression]><!-->\n" . $elements['#prefix'];
        $elements['#suffix'] .= "<!--<![endif]-->\n";
      }
    
      return $elements;
    }
    
    /**
     * #pre_render callback to render a link into #markup.
     *
     * Doing so during pre_render gives modules a chance to alter the link parts.
     *
     * @param $elements
     *   A structured array whose keys form the arguments to l():
     *   - #title: The link text to pass as argument to l().
     *   - #href: The URL path component to pass as argument to l().
     *   - #options: (optional) An array of options to pass to l().
     *
     * @return
     *   The passed-in elements containing a rendered link in '#markup'.
     */
    function drupal_pre_render_link($element) {
      // By default, link options to pass to l() are normally set in #options.
      $element += array('#options' => array());
      // However, within the scope of renderable elements, #attributes is a valid
      // way to specify attributes, too. Take them into account, but do not override
      // attributes from #options.
      if (isset($element['#attributes'])) {
        $element['#options'] += array('attributes' => array());
        $element['#options']['attributes'] += $element['#attributes'];
      }
    
      // This #pre_render callback can be invoked from inside or outside of a Form
      // API context, and depending on that, a HTML ID may be already set in
      // different locations. #options should have precedence over Form API's #id.
      // #attributes have been taken over into #options above already.
      if (isset($element['#options']['attributes']['id'])) {
        $element['#id'] = $element['#options']['attributes']['id'];
      }
      elseif (isset($element['#id'])) {
        $element['#options']['attributes']['id'] = $element['#id'];
      }
    
      // Conditionally invoke ajax_pre_render_element(), if #ajax is set.
      if (isset($element['#ajax']) && !isset($element['#ajax_processed'])) {
        // If no HTML ID was found above, automatically create one.
        if (!isset($element['#id'])) {
          $element['#id'] = $element['#options']['attributes']['id'] = drupal_html_id('ajax-link');
        }
        // If #ajax['path] was not specified, use the href as Ajax request URL.
        if (!isset($element['#ajax']['path'])) {
          $element['#ajax']['path'] = $element['#href'];
          $element['#ajax']['options'] = $element['#options'];
        }
        $element = ajax_pre_render_element($element);
      }
    
      $element['#markup'] = l($element['#title'], $element['#href'], $element['#options']);
      return $element;
    }
    
    /**
     * #pre_render callback that collects child links into a single array.
     *
     * This function can be added as a pre_render callback for a renderable array,
     * usually one which will be themed by theme_links(). It iterates through all
     * unrendered children of the element, collects any #links properties it finds,
     * merges them into the parent element's #links array, and prevents those
     * children from being rendered separately.
     *
     * The purpose of this is to allow links to be logically grouped into related
     * categories, so that each child group can be rendered as its own list of
     * links if drupal_render() is called on it, but calling drupal_render() on the
     * parent element will still produce a single list containing all the remaining
     * links, regardless of what group they were in.
     *
     * A typical example comes from node links, which are stored in a renderable
     * array similar to this:
     * @code
     * $node->content['links'] = array(
     *   '#theme' => 'links__node',
     *   '#pre_render' = array('drupal_pre_render_links'),
     *   'comment' => array(
     *     '#theme' => 'links__node__comment',
     *     '#links' => array(
     *       // An array of links associated with node comments, suitable for
     *       // passing in to theme_links().
     *     ),
     *   ),
     *   'statistics' => array(
     *     '#theme' => 'links__node__statistics',
     *     '#links' => array(
     *       // An array of links associated with node statistics, suitable for
     *       // passing in to theme_links().
     *     ),
     *   ),
     *   'translation' => array(
     *     '#theme' => 'links__node__translation',
     *     '#links' => array(
     *       // An array of links associated with node translation, suitable for
     *       // passing in to theme_links().
     *     ),
     *   ),
     * );
     * @endcode
     *
     * In this example, the links are grouped by functionality, which can be
     * helpful to themers who want to display certain kinds of links independently.
     * For example, adding this code to node.tpl.php will result in the comment
     * links being rendered as a single list:
     * @code
     * print render($content['links']['comment']);
     * @endcode
     *
     * (where $node->content has been transformed into $content before handing
     * control to the node.tpl.php template).
     *
     * The pre_render function defined here allows the above flexibility, but also
     * allows the following code to be used to render all remaining links into a
     * single list, regardless of their group:
     * @code
     * print render($content['links']);
     * @endcode
     *
     * In the above example, this will result in the statistics and translation
     * links being rendered together in a single list (but not the comment links,
     * which were rendered previously on their own).
     *
     * Because of the way this function works, the individual properties of each
     * group (for example, a group-specific #theme property such as
     * 'links__node__comment' in the example above, or any other property such as
     * #attributes or #pre_render that is attached to it) are only used when that
     * group is rendered on its own. When the group is rendered together with other
     * children, these child-specific properties are ignored, and only the overall
     * properties of the parent are used.
     */
    function drupal_pre_render_links($element) {
      $element += array('#links' => array());
      foreach (element_children($element) as $key) {
        $child = &$element[$key];
        // If the child has links which have not been printed yet and the user has
        // access to it, merge its links in to the parent.
        if (isset($child['#links']) && empty($child['#printed']) && (!isset($child['#access']) || $child['#access'])) {
          $element['#links'] += $child['#links'];
          // Mark the child as having been printed already (so that its links
          // cannot be mistakenly rendered twice).
          $child['#printed'] = TRUE;
        }
      }
      return $element;
    }
    
    /**
     * #pre_render callback to append contents in #markup to #children.
     *
     * This needs to be a #pre_render callback, because eventually assigned
     * #theme_wrappers will expect the element's rendered content in #children.
     * Note that if also a #theme is defined for the element, then the result of
     * the theme callback will override #children.
     *
     * @see drupal_render()
     *
     * @param $elements
     *   A structured array using the #markup key.
     *
     * @return
     *   The passed-in elements, but #markup appended to #children.
     */
    function drupal_pre_render_markup($elements) {
      $elements['#children'] = $elements['#markup'];
      return $elements;
    }
    
    /**
     * Renders the page, including all theming.
     *
     * @param $page
     *   A string or array representing the content of a page. The array consists of
     *   the following keys:
     *   - #type: Value is always 'page'. This pushes the theming through page.tpl.php (required).
     *   - #show_messages: Suppress drupal_get_message() items. Used by Batch API (optional).
     *
     * @see hook_page_alter()
     * @see element_info()
     */
    function drupal_render_page($page) {
      $main_content_display = &drupal_static('system_main_content_added', FALSE);
    
      // Allow menu callbacks to return strings or arbitrary arrays to render.
      // If the array returned is not of #type page directly, we need to fill
      // in the page with defaults.
      if (is_string($page) || (is_array($page) && (!isset($page['#type']) || ($page['#type'] != 'page')))) {
        drupal_set_page_content($page);
        $page = element_info('page');
      }
    
      // Modules can add elements to $page as needed in hook_page_build().
      foreach (module_implements('page_build') as $module) {
        $function = $module . '_page_build';
        $function($page);
      }
      // Modules alter the $page as needed. Blocks are populated into regions like
      // 'sidebar_first', 'footer', etc.
      drupal_alter('page', $page);
    
      // If no module has taken care of the main content, add it to the page now.
      // This allows the site to still be usable even if no modules that
      // control page regions (for example, the Block module) are enabled.
      if (!$main_content_display) {
        $page['content']['system_main'] = drupal_set_page_content();
      }
    
      return drupal_render($page);
    }
    
    /**
     * Renders HTML given a structured array tree.
     *
     * Recursively iterates over each of the array elements, generating HTML code.
     *
     * HTML generation is controlled by two properties containing theme functions,
     * #theme and #theme_wrappers.
     *
     * #theme is the theme function called first. If it is set and the element has
     * any children, they have to be rendered there. For elements that are not
     * allowed to have any children, e.g. buttons or textfields, it can be used to
     * render the element itself. If #theme is not present and the element has
     * children, they are rendered and concatenated into a string by
     * drupal_render_children().
     *
     * The #theme_wrappers property contains an array of theme functions which will
     * be called, in order, after #theme has run. These can be used to add further
     * markup around the rendered children; e.g., fieldsets add the required markup
     * for a fieldset around their rendered child elements. All wrapper theme
     * functions have to include the element's #children property in their output,
     * as it contains the output of the previous theme functions and the rendered
     * children.
     *
     * For example, for the form element type, by default only the #theme_wrappers
     * property is set, which adds the form markup around the rendered child
     * elements of the form. This allows you to set the #theme property on a
     * specific form to a custom theme function, giving you complete control over
     * the placement of the form's children while not at all having to deal with
     * the form markup itself.
     *
     * drupal_render() can optionally cache the rendered output of elements to
     * improve performance. To use drupal_render() caching, set the element's #cache
     * property to an associative array with one or several of the following keys:
     *    - 'keys': An array of one or more keys that identify the element. If 'keys'
     *       is set, the cache ID is created automatically from these keys. See
     *       drupal_render_cid_create().
     *    - 'granularity' (optional): Define the cache granularity using binary
     *       combinations of the cache granularity constants, e.g. DRUPAL_CACHE_PER_USER
     *       to cache for each user separately or
     *       DRUPAL_CACHE_PER_PAGE | DRUPAL_CACHE_PER_ROLE to cache separately for each
     *       page and role. If not specified the element is cached globally for each
     *       theme and language.
     *    - 'cid': Specify the cache ID directly. Either 'keys' or 'cid' is required.
     *       If 'cid' is set, 'keys' and 'granularity' are ignored. Use only if you
     *       have special requirements.
     *    - 'expire': Set to one of the cache lifetime constants.
     *    - 'bin': Specify a cache bin to cache the element in. Defaults to 'cache'.
     *
     * This function is usually called from within another function, like
     * drupal_get_form() or a theme function. Elements are sorted internally
     * using uasort(). Since this is expensive, when passing already sorted
     * elements to drupal_render(), for example from a database query, set
     * $elements['#sorted'] = TRUE to avoid sorting them a second time.
     *
     * drupal_render() flags each element with a '#printed' status to indicate that
     * the element has been rendered, which allows individual elements of a given
     * array to be rendered independently and prevents them from being rendered
     * more than once on subsequent calls to drupal_render() (e.g., as part of a
     * larger array). If the same array or array element is passed more than once
     * to drupal_render(), it simply returns a NULL value.
     *
     * @param $elements
     *   The structured array describing the data to be rendered.
     * @return
     *   The rendered HTML.
     */
    function drupal_render(&$elements) {
      // Early-return nothing if user does not have access.
      if (empty($elements) || (isset($elements['#access']) && !$elements['#access'])) {
        return;
      }
    
      // Do not print elements twice.
      if (!empty($elements['#printed'])) {
        return;
      }
    
      // Try to fetch the element's markup from cache and return.
      if (isset($elements['#cache']) && $cached_output = drupal_render_cache_get($elements)) {
        return $cached_output;
      }
    
      // If #markup is set, ensure #type is set. This allows to specify just #markup
      // on an element without setting #type.
      if (isset($elements['#markup']) && !isset($elements['#type'])) {
        $elements['#type'] = 'markup';
      }
    
      // If the default values for this element have not been loaded yet, populate
      // them.
      if (isset($elements['#type']) && empty($elements['#defaults_loaded'])) {
        $elements += element_info($elements['#type']);
      }
    
      // Make any final changes to the element before it is rendered. This means
      // that the $element or the children can be altered or corrected before the
      // element is rendered into the final text.
      if (isset($elements['#pre_render'])) {
        foreach ($elements['#pre_render'] as $function) {
          if (function_exists($function)) {
            $elements = $function($elements);
          }
        }
      }
    
      // Allow #pre_render to abort rendering.
      if (!empty($elements['#printed'])) {
        return;
      }
    
      // Get the children of the element, sorted by weight.
      $children = element_children($elements, TRUE);
    
      // Initialize this element's #children, unless a #pre_render callback already
      // preset #children.
      if (!isset($elements['#children'])) {
        $elements['#children'] = '';
      }
      // Call the element's #theme function if it is set. Then any children of the
      // element have to be rendered there.
      if (isset($elements['#theme'])) {
        $elements['#children'] = theme($elements['#theme'], $elements);
      }
      // If #theme was not set and the element has children, render them now.
      // This is the same process as drupal_render_children() but is inlined
      // for speed.
      if ($elements['#children'] == '') {
        foreach ($children as $key) {
          $elements['#children'] .= drupal_render($elements[$key]);
        }
      }
    
      // Let the theme functions in #theme_wrappers add markup around the rendered
      // children.
      if (isset($elements['#theme_wrappers'])) {
        foreach ($elements['#theme_wrappers'] as $theme_wrapper) {
          $elements['#children'] = theme($theme_wrapper, $elements);
        }
      }
    
      // Filter the outputted content and make any last changes before the
      // content is sent to the browser. The changes are made on $content
      // which allows the output'ed text to be filtered.
      if (isset($elements['#post_render'])) {
        foreach ($elements['#post_render'] as $function) {
          if (function_exists($function)) {
            $elements['#children'] = $function($elements['#children'], $elements);
          }
        }
      }
    
      // Add any JavaScript state information associated with the element.
      if (!empty($elements['#states'])) {
        drupal_process_states($elements);
      }
    
      // Add additional libraries, CSS, JavaScript an other custom
      // attached data associated with this element.
      if (!empty($elements['#attached'])) {
        drupal_process_attached($elements);
      }
    
      $prefix = isset($elements['#prefix']) ? $elements['#prefix'] : '';
      $suffix = isset($elements['#suffix']) ? $elements['#suffix'] : '';
      $output = $prefix . $elements['#children'] . $suffix;
    
      // Cache the processed element if #cache is set.
      if (isset($elements['#cache'])) {
        drupal_render_cache_set($output, $elements);
      }
    
      $elements['#printed'] = TRUE;
      return $output;
    }
    
    /**
     * Render children of an element and concatenate them.
     *
     * This renders all children of an element using drupal_render() and then
     * joins them together into a single string.
     *
     * @param $element
     *   The structured array whose children shall be rendered.
     * @param $children_keys
     *   If the keys of the element's children are already known, they can be passed
     *   in to save another run of element_children().
     */
    function drupal_render_children(&$element, $children_keys = NULL) {
      if ($children_keys === NULL) {
        $children_keys = element_children($element);
      }
      $output = '';
      foreach ($children_keys as $key) {
        if (!empty($element[$key])) {
          $output .= drupal_render($element[$key]);
        }
      }
      return $output;
    }
    
    /**
     * Render an element.
     *
     * This function renders an element using drupal_render(). The top level
     * element is shown with show() before rendering, so it will always be rendered
     * even if hide() had been previously used on it.
     *
     * @param $element
     *   The element to be rendered.
     *
     * @return
     *   The rendered element.
     *
     * @see drupal_render()
     * @see show()
     * @see hide()
     */
    function render(&$element) {
      if (is_array($element)) {
        show($element);
        return drupal_render($element);
      }
      else {
        // Safe-guard for inappropriate use of render() on flat variables: return
        // the variable as-is.
        return $element;
      }
    }
    
    /**
     * Hide an element from later rendering.
     *
     * The first time render() or drupal_render() is called on an element tree,
     * as each element in the tree is rendered, it is marked with a #printed flag
     * and the rendered children of the element are cached. Subsequent calls to
     * render() or drupal_render() will not traverse the child tree of this element
     * again: they will just use the cached children. So if you want to hide an
     * element, be sure to call hide() on the element before its parent tree is
     * rendered for the first time, as it will have no effect on subsequent
     * renderings of the parent tree.
     *
     * @param $element
     *   The element to be hidden.
     *
     * @return
     *   The element.
     *
     * @see render()
     * @see show()
     */
    function hide(&$element) {
      $element['#printed'] = TRUE;
      return $element;
    }
    
    /**
     * Show a hidden element for later rendering.
     *
     * You can also use render($element), which shows the element while rendering
     * it.
     *
     * The first time render() or drupal_render() is called on an element tree,
     * as each element in the tree is rendered, it is marked with a #printed flag
     * and the rendered children of the element are cached. Subsequent calls to
     * render() or drupal_render() will not traverse the child tree of this element
     * again: they will just use the cached children. So if you want to show an
     * element, be sure to call show() on the element before its parent tree is
     * rendered for the first time, as it will have no effect on subsequent
     * renderings of the parent tree.
     *
     * @param $element
     *   The element to be shown.
     *
     * @return
     *   The element.
     *
     * @see render()
     * @see hide()
     */
    function show(&$element) {
      $element['#printed'] = FALSE;
      return $element;
    }
    
    /**
     * Get the rendered output of a renderable element from cache.
     *
     * @see drupal_render()
     * @see drupal_render_cache_set()
     *
     * @param $elements
     *   A renderable array.
     * @return
     *   A markup string containing the rendered content of the element, or FALSE
     *   if no cached copy of the element is available.
     */
    function drupal_render_cache_get($elements) {
      if (!in_array($_SERVER['REQUEST_METHOD'], array('GET', 'HEAD')) || !$cid = drupal_render_cid_create($elements)) {
        return FALSE;
      }
      $bin = isset($elements['#cache']['bin']) ? $elements['#cache']['bin'] : 'cache';
    
      if (!empty($cid) && $cache = cache_get($cid, $bin)) {
        // Add additional libraries, JavaScript, CSS and other data attached
        // to this element.
        if (isset($cache->data['#attached'])) {
          drupal_process_attached($cache->data);
        }
        // Return the rendered output.
        return $cache->data['#markup'];
      }
      return FALSE;
    }
    
    /**
     * Cache the rendered output of a renderable element.
     *
     * This is called by drupal_render() if the #cache property is set on an element.
     *
     * @see drupal_render()
     * @see drupal_render_cache_get()
     *
     * @param $markup
     *   The rendered output string of $elements.
     * @param $elements
     *   A renderable array.
     */
    function drupal_render_cache_set(&$markup, $elements) {
      // Create the cache ID for the element.
      if (!in_array($_SERVER['REQUEST_METHOD'], array('GET', 'HEAD')) || !$cid = drupal_render_cid_create($elements)) {
        return FALSE;
      }
    
      // Cache implementations are allowed to modify the markup, to support
      // replacing markup with edge-side include commands. The supporting cache
      // backend will store the markup in some other key (like
      // $data['#real-value']) and return an include command instead. When the
      // ESI command is executed by the content accelerator, the real value can
      // be retrieved and used.
      $data['#markup'] = &$markup;
      // Persist attached data associated with this element.
      $attached = drupal_render_collect_attached($elements, TRUE);
      if ($attached) {
        $data['#attached'] = $attached;
      }
      $bin = isset($elements['#cache']['bin']) ? $elements['#cache']['bin'] : 'cache';
      $expire = isset($elements['#cache']['expire']) ? $elements['#cache']['expire'] : CACHE_PERMANENT;
      cache_set($cid, $data, $bin, $expire);
    }
    
    /**
     * Collect #attached for an element and all child elements into a single array.
     *
     * When caching elements, it is necessary to collect all libraries, JavaScript
     * and CSS into a single array, from both the element itself and all child
     * elements. This allows drupal_render() to add these back to the page when the
     * element is returned from cache.
     *
     * @param $elements
     *   The element to collect #attached from.
     * @param $return
     *   Whether to return the attached elements and reset the internal static.
     *
     * @return
     *   The #attached array for this element and its descendants.
     */
    function drupal_render_collect_attached($elements, $return = FALSE) {
      $attached = &drupal_static(__FUNCTION__, array());
    
      // Collect all #attached for this element.
      if (isset($elements['#attached'])) {
        foreach ($elements['#attached'] as $key => $value) {
          if (!isset($attached[$key])) {
            $attached[$key] = array();
          }
          $attached[$key] = array_merge($attached[$key], $value);
        }
      }
      if ($children = element_children($elements)) {
        foreach ($children as $child) {
          drupal_render_collect_attached($elements[$child]);
        }
      }
    
      // If this was the first call to the function, return all attached elements
      // and reset the static cache.
      if ($return) {
        $return = $attached;
        $attached = array();
        return $return;
      }
    }
    
    /**
     * Prepare an element for caching based on a query. This smart caching strategy
     * saves Drupal from querying and rendering to HTML when the underlying query is
     * unchanged.
     *
     * Expensive queries should use the query builder to create the query and then
     * call this function. Executing the query and formatting results should happen
     * in a #pre_render callback.
     *
     * @param $query
     *   A select query object as returned by db_select().
     * @param $function
     *   The name of the function doing this caching. A _pre_render suffix will be
     *   added to this string and is also part of the cache key in
     *   drupal_render_cache_set() and drupal_render_cache_get().
     * @param $expire
     *   The cache expire time, passed eventually to cache_set().
     * @param $granularity
     *   One or more granularity constants passed to drupal_render_cid_parts().
     *
     * @return
     *   A renderable array with the following keys and values:
     *   - #query: The passed-in $query.
     *   - #pre_render: $function with a _pre_render suffix.
     *   - #cache: An associative array prepared for drupal_render_cache_set().
     */
    function drupal_render_cache_by_query($query, $function, $expire = CACHE_TEMPORARY, $granularity = NULL) {
      $cache_keys = array_merge(array($function), drupal_render_cid_parts($granularity));
      $query->preExecute();
      $cache_keys[] = hash('sha256', serialize(array((string) $query, $query->getArguments())));
      return array(
        '#query' => $query,
        '#pre_render' => array($function . '_pre_render'),
        '#cache' => array(
          'keys' => $cache_keys,
          'expire' => $expire,
        ),
      );
    }
    
    /**
     * Helper function for building cache ids.
     *
     * @param $granularity
     *   One or more cache granularity constants, e.g. DRUPAL_CACHE_PER_USER to cache
     *   for each user separately or DRUPAL_CACHE_PER_PAGE | DRUPAL_CACHE_PER_ROLE to
     *   cache separately for each page and role.
     *
     * @return
     *   An array of cache ID parts, always containing the active theme. If the
     *   locale module is enabled it also contains the active language. If
     *   $granularity was passed in, more parts are added.
     */
    function drupal_render_cid_parts($granularity = NULL) {
      global $theme, $base_root, $user;
    
      $cid_parts[] = $theme;
      // If Locale is enabled but we have only one language we do not need it as cid
      // part.
      if (drupal_multilingual()) {
        foreach (language_types_configurable() as $language_type) {
          $cid_parts[] = $GLOBALS[$language_type]->language;
        }
      }
    
      if (!empty($granularity)) {
        // 'PER_ROLE' and 'PER_USER' are mutually exclusive. 'PER_USER' can be a
        // resource drag for sites with many users, so when a module is being
        // equivocal, we favor the less expensive 'PER_ROLE' pattern.
        if ($granularity & DRUPAL_CACHE_PER_ROLE) {
          $cid_parts[] = 'r.' . implode(',', array_keys($user->roles));
        }
        elseif ($granularity & DRUPAL_CACHE_PER_USER) {
          $cid_parts[] = "u.$user->uid";
        }
    
        if ($granularity & DRUPAL_CACHE_PER_PAGE) {
          $cid_parts[] = $base_root . request_uri();
        }
      }
    
      return $cid_parts;
    }
    
    /**
     * Create the cache ID for a renderable element.
     *
     * This creates the cache ID string, either by returning the #cache['cid']
     * property if present or by building the cache ID out of the #cache['keys']
     * and, optionally, the #cache['granularity'] properties.
     *
     * @param $elements
     *   A renderable array.
     *
     * @return
     *   The cache ID string, or FALSE if the element may not be cached.
     */
    function drupal_render_cid_create($elements) {
      if (isset($elements['#cache']['cid'])) {
        return $elements['#cache']['cid'];
      }
      elseif (isset($elements['#cache']['keys'])) {
        $granularity = isset($elements['#cache']['granularity']) ? $elements['#cache']['granularity'] : NULL;
        // Merge in additional cache ID parts based provided by drupal_render_cid_parts().
        $cid_parts = array_merge($elements['#cache']['keys'], drupal_render_cid_parts($granularity));
        return implode(':', $cid_parts);
      }
      return FALSE;
    }
    
    /**
     * Function used by uasort to sort structured arrays by weight.
     */
    function element_sort($a, $b) {
      $a_weight = (is_array($a) && isset($a['#weight'])) ? $a['#weight'] : 0;
      $b_weight = (is_array($b) && isset($b['#weight'])) ? $b['#weight'] : 0;
      if ($a_weight == $b_weight) {
        return 0;
      }
      return ($a_weight < $b_weight) ? -1 : 1;
    }
    
    /**
     * Array sorting callback; sorts elements by title.
     */
    function element_sort_by_title($a, $b) {
      $a_title = (is_array($a) && isset($a['#title'])) ? $a['#title'] : '';
      $b_title = (is_array($b) && isset($b['#title'])) ? $b['#title'] : '';
      return strnatcasecmp($a_title, $b_title);
    }
    
    /**
     * Retrieve the default properties for the defined element type.
     *
     * @param $type
     *   An element type as defined by hook_element_info().
     */
    function element_info($type) {
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['cache'] = &drupal_static(__FUNCTION__);
      }
      $cache = &$drupal_static_fast['cache'];
    
      if (!isset($cache)) {
        $cache = module_invoke_all('element_info');
        foreach ($cache as $element_type => $info) {
          $cache[$element_type]['#type'] = $element_type;
        }
        // Allow modules to alter the element type defaults.
        drupal_alter('element_info', $cache);
      }
    
      return isset($cache[$type]) ? $cache[$type] : array();
    }
    
    /**
     * Retrieve a single property for the defined element type.
     *
     * @param $type
     *   An element type as defined by hook_element_info().
     * @param $property_name
     *   The property within the element type that should be returned.
     * @param $default
     *   (Optional) The value to return if the element type does not specify a
     *   value for the property. Defaults to NULL.
     */
    function element_info_property($type, $property_name, $default = NULL) {
      return (($info = element_info($type)) && array_key_exists($property_name, $info)) ? $info[$property_name] : $default;
    }
    
    /**
     * Function used by uasort to sort structured arrays by weight, without the property weight prefix.
     */
    function drupal_sort_weight($a, $b) {
      $a_weight = (is_array($a) && isset($a['weight'])) ? $a['weight'] : 0;
      $b_weight = (is_array($b) && isset($b['weight'])) ? $b['weight'] : 0;
      if ($a_weight == $b_weight) {
        return 0;
      }
      return ($a_weight < $b_weight) ? -1 : 1;
    }
    
    /**
     * Array sorting callback; sorts elements by 'title' key.
     */
    function drupal_sort_title($a, $b) {
      if (!isset($b['title'])) {
        return -1;
      }
      if (!isset($a['title'])) {
        return 1;
      }
      return strcasecmp($a['title'], $b['title']);
    }
    
    /**
     * Check if the key is a property.
     */
    function element_property($key) {
      return $key[0] == '#';
    }
    
    /**
     * Get properties of a structured array element. Properties begin with '#'.
     */
    function element_properties($element) {
      return array_filter(array_keys((array) $element), 'element_property');
    }
    
    /**
     * Check if the key is a child.
     */
    function element_child($key) {
      return !isset($key[0]) || $key[0] != '#';
    }
    
    /**
     * Return the children of an element, optionally sorted by weight.
     *
     * @param $elements
     *   The element to be sorted.
     * @param $sort
     *   Boolean to indicate whether the children should be sorted by weight.
     * @return
     *   The array keys of the element's children.
     */
    function element_children(&$elements, $sort = FALSE) {
      // Do not attempt to sort elements which have already been sorted.
      $sort = isset($elements['#sorted']) ? !$elements['#sorted'] : $sort;
    
      // Filter out properties from the element, leaving only children.
      $children = array();
      $sortable = FALSE;
      foreach ($elements as $key => $value) {
        if ($key === '' || $key[0] !== '#') {
          $children[$key] = $value;
          if (is_array($value) && isset($value['#weight'])) {
            $sortable = TRUE;
          }
        }
      }
      // Sort the children if necessary.
      if ($sort && $sortable) {
        uasort($children, 'element_sort');
        // Put the sorted children back into $elements in the correct order, to
        // preserve sorting if the same element is passed through
        // element_children() twice.
        foreach ($children as $key => $child) {
          unset($elements[$key]);
          $elements[$key] = $child;
        }
        $elements['#sorted'] = TRUE;
      }
    
      return array_keys($children);
    }
    
    /**
     * Return the visibile children of an element.
     *
     * @param $elements
     *   The parent element.
     * @return
     *   The array keys of the element's visible children.
     */
    function element_get_visible_children(array $elements) {
      $visible_children = array();
    
      foreach (element_children($elements) as $key) {
        $child = $elements[$key];
    
        // Skip un-accessible children.
        if (isset($child['#access']) && !$child['#access']) {
          continue;
        }
    
        // Skip value and hidden elements, since they are not rendered.
        if (isset($child['#type']) && in_array($child['#type'], array('value', 'hidden'))) {
          continue;
        }
    
        $visible_children[$key] = $child;
      }
    
      return array_keys($visible_children);
    }
    
    /**
     * Sets HTML attributes based on element properties.
     *
     * @param $element
     *   The renderable element to process.
     * @param $map
     *   An associative array whose keys are element property names and whose values
     *   are the HTML attribute names to set for corresponding the property; e.g.,
     *   array('#propertyname' => 'attributename'). If both names are identical
     *   except for the leading '#', then an attribute name value is sufficient and
     *   no property name needs to be specified.
     */
    function element_set_attributes(array &$element, array $map) {
      foreach ($map as $property => $attribute) {
        // If the key is numeric, the attribute name needs to be taken over.
        if (is_int($property)) {
          $property = '#' . $attribute;
        }
        // Do not overwrite already existing attributes.
        if (isset($element[$property]) && !isset($element['#attributes'][$attribute])) {
          $element['#attributes'][$attribute] = $element[$property];
        }
      }
    }
    
    /**
     * Sets a value in a nested array with variable depth.
     *
     * This helper function should be used when the depth of the array element you
     * are changing may vary (that is, the number of parent keys is variable). It
     * is primarily used for form structures and renderable arrays.
     *
     * Example:
     * @code
     * // Assume you have a 'signature' element somewhere in a form. It might be:
     * $form['signature_settings']['signature'] = array(
     *   '#type' => 'text_format',
     *   '#title' => t('Signature'),
     * );
     * // Or, it might be further nested:
     * $form['signature_settings']['user']['signature'] = array(
     *   '#type' => 'text_format',
     *   '#title' => t('Signature'),
     * );
     * @endcode
     *
     * To deal with the situation, the code needs to figure out the route to the
     * element, given an array of parents that is either
     * @code array('signature_settings', 'signature') @endcode in the first case or
     * @code array('signature_settings', 'user', 'signature') @endcode in the second
     * case.
     *
     * Without this helper function the only way to set the signature element in one
     * line would be using eval(), which should be avoided:
     * @code
     * // Do not do this! Avoid eval().
     * eval('$form[\'' . implode("']['", $parents) . '\'] = $element;');
     * @endcode
     *
     * Instead, use this helper function:
     * @code
     * drupal_array_set_nested_value($form, $parents, $element);
     * @endcode
     *
     * However if the number of array parent keys is static, the value should always
     * be set directly rather than calling this function. For instance, for the
     * first example we could just do:
     * @code
     * $form['signature_settings']['signature'] = $element;
     * @endcode
     *
     * @param $array
     *   A reference to the array to modify.
     * @param $parents
     *   An array of parent keys, starting with the outermost key.
     * @param $value
     *   The value to set.
     * @param $force
     *   (Optional) If TRUE, the value is forced into the structure even if it
     *   requires the deletion of an already existing non-array parent value. If
     *   FALSE, PHP throws an error if trying to add into a value that is not an
     *   array. Defaults to FALSE.
     *
     * @see drupal_array_get_nested_value()
     */
    function drupal_array_set_nested_value(array &$array, array $parents, $value, $force = FALSE) {
      $ref = &$array;
      foreach ($parents as $parent) {
        // PHP auto-creates container arrays and NULL entries without error if $ref
        // is NULL, but throws an error if $ref is set, but not an array.
        if ($force && isset($ref) && !is_array($ref)) {
          $ref = array();
        }
        $ref = &$ref[$parent];
      }
      $ref = $value;
    }
    
    /**
     * Retrieves a value from a nested array with variable depth.
     *
     * This helper function should be used when the depth of the array element being
     * retrieved may vary (that is, the number of parent keys is variable). It is
     * primarily used for form structures and renderable arrays.
     *
     * Without this helper function the only way to get a nested array value with
     * variable depth in one line would be using eval(), which should be avoided:
     * @code
     * // Do not do this! Avoid eval().
     * // May also throw a PHP notice, if the variable array keys do not exist.
     * eval('$value = $array[\'' . implode("']['", $parents) . "'];");
     * @endcode
     *
     * Instead, use this helper function:
     * @code
     * $value = drupal_array_get_nested_value($form, $parents);
     * @endcode
     *
     * The return value will be NULL, regardless of whether the actual value is NULL
     * or whether the requested key does not exist. If it is required to know
     * whether the nested array key actually exists, pass a third argument that is
     * altered by reference:
     * @code
     * $key_exists = NULL;
     * $value = drupal_array_get_nested_value($form, $parents, $key_exists);
     * if ($key_exists) {
     *   // ... do something with $value ...
     * }
     * @endcode
     *
     * However if the number of array parent keys is static, the value should always
     * be retrieved directly rather than calling this function. For instance:
     * @code
     * $value = $form['signature_settings']['signature'];
     * @endcode
     *
     * @param $array
     *   The array from which to get the value.
     * @param $parents
     *   An array of parent keys of the value, starting with the outermost key.
     * @param $key_exists
     *   (optional) If given, an already defined variable that is altered by
     *   reference.
     *
     * @return
     *   The requested nested value. Possibly NULL if the value is NULL or not all
     *   nested parent keys exist. $key_exists is altered by reference and is a
     *   Boolean that indicates whether all nested parent keys exist (TRUE) or not
     *   (FALSE). This allows to distinguish between the two possibilities when NULL
     *   is returned.
     *
     * @see drupal_array_set_nested_value()
     */
    function drupal_array_get_nested_value(array &$array, array $parents, &$key_exists = NULL) {
      $ref = &$array;
      foreach ($parents as $parent) {
        if (is_array($ref) && array_key_exists($parent, $ref)) {
          $ref = &$ref[$parent];
        }
        else {
          $key_exists = FALSE;
          return NULL;
        }
      }
      $key_exists = TRUE;
      return $ref;
    }
    
    /**
     * Determines whether a nested array with variable depth contains all of the requested keys.
     *
     * This helper function should be used when the depth of the array element to be
     * checked may vary (that is, the number of parent keys is variable). See
     * drupal_array_set_nested_value() for details. It is primarily used for form
     * structures and renderable arrays.
     *
     * If it is required to also get the value of the checked nested key, use
     * drupal_array_get_nested_value() instead.
     *
     * If the number of array parent keys is static, this helper function is
     * unnecessary and the following code can be used instead:
     * @code
     * $value_exists = isset($form['signature_settings']['signature']);
     * $key_exists = array_key_exists('signature', $form['signature_settings']);
     * @endcode
     *
     * @param $array
     *   The array with the value to check for.
     * @param $parents
     *   An array of parent keys of the value, starting with the outermost key.
     *
     * @return
     *   TRUE if all the parent keys exist, FALSE otherwise.
     *
     * @see drupal_array_get_nested_value()
     */
    function drupal_array_nested_key_exists(array $array, array $parents) {
      // Although this function is similar to PHP's array_key_exists(), its
      // arguments should be consistent with drupal_array_get_nested_value().
      $key_exists = NULL;
      drupal_array_get_nested_value($array, $parents, $key_exists);
      return $key_exists;
    }
    
    /**
     * Provide theme registration for themes across .inc files.
     */
    function drupal_common_theme() {
      return array(
        // theme.inc
        'html' => array(
          'render element' => 'page',
          'template' => 'html',
        ),
        'page' => array(
          'render element' => 'page',
          'template' => 'page',
        ),
        'region' => array(
          'render element' => 'elements',
          'template' => 'region',
        ),
        'status_messages' => array(
          'variables' => array('display' => NULL),
        ),
        'link' => array(
          'variables' => array('text' => NULL, 'path' => NULL, 'options' => array()),
        ),
        'links' => array(
          'variables' => array('links' => NULL, 'attributes' => array('class' => array('links')), 'heading' => array()),
        ),
        'image' => array(
          // HTML 4 and XHTML 1.0 always require an alt attribute. The HTML 5 draft
          // allows the alt attribute to be omitted in some cases. Therefore,
          // default the alt attribute to an empty string, but allow code calling
          // theme('image') to pass explicit NULL for it to be omitted. Usually,
          // neither omission nor an empty string satisfies accessibility
          // requirements, so it is strongly encouraged for code calling
          // theme('image') to pass a meaningful value for the alt variable.
          // - http://www.w3.org/TR/REC-html40/struct/objects.html#h-13.8
          // - http://www.w3.org/TR/xhtml1/dtds.html
          // - http://dev.w3.org/html5/spec/Overview.html#alt
          // The title attribute is optional in all cases, so it is omitted by
          // default.
          'variables' => array('path' => NULL, 'width' => NULL, 'height' => NULL, 'alt' => '', 'title' => NULL, 'attributes' => array()),
        ),
        'breadcrumb' => array(
          'variables' => array('breadcrumb' => NULL),
        ),
        'help' => array(
          'variables' => array(),
        ),
        'table' => array(
          'variables' => array('header' => NULL, 'rows' => NULL, 'attributes' => array(), 'caption' => NULL, 'colgroups' => array(), 'sticky' => TRUE, 'empty' => ''),
        ),
        'tablesort_indicator' => array(
          'variables' => array('style' => NULL),
        ),
        'mark' => array(
          'variables' => array('type' => MARK_NEW),
        ),
        'item_list' => array(
          'variables' => array('items' => array(), 'title' => NULL, 'type' => 'ul', 'attributes' => array()),
        ),
        'more_help_link' => array(
          'variables' => array('url' => NULL),
        ),
        'feed_icon' => array(
          'variables' => array('url' => NULL, 'title' => NULL),
        ),
        'more_link' => array(
          'variables' => array('url' => NULL, 'title' => NULL)
        ),
        'username' => array(
          'variables' => array('account' => NULL),
        ),
        'progress_bar' => array(
          'variables' => array('percent' => NULL, 'message' => NULL),
        ),
        'indentation' => array(
          'variables' => array('size' => 1),
        ),
        'html_tag' => array(
          'render element' => 'element',
        ),
        // from theme.maintenance.inc
        'maintenance_page' => array(
          'variables' => array('content' => NULL, 'show_messages' => TRUE),
          'template' => 'maintenance-page',
        ),
        'update_page' => array(
          'variables' => array('content' => NULL, 'show_messages' => TRUE),
        ),
        'install_page' => array(
          'variables' => array('content' => NULL),
        ),
        'task_list' => array(
          'variables' => array('items' => NULL, 'active' => NULL),
        ),
        'authorize_message' => array(
          'variables' => array('message' => NULL, 'success' => TRUE),
        ),
        'authorize_report' => array(
          'variables' => array('messages' => array()),
        ),
        // from pager.inc
        'pager' => array(
          'variables' => array('tags' => array(), 'element' => 0, 'parameters' => array(), 'quantity' => 9),
        ),
        'pager_first' => array(
          'variables' => array('text' => NULL, 'element' => 0, 'parameters' => array()),
        ),
        'pager_previous' => array(
          'variables' => array('text' => NULL, 'element' => 0, 'interval' => 1, 'parameters' => array()),
        ),
        'pager_next' => array(
          'variables' => array('text' => NULL, 'element' => 0, 'interval' => 1, 'parameters' => array()),
        ),
        'pager_last' => array(
          'variables' => array('text' => NULL, 'element' => 0, 'parameters' => array()),
        ),
        'pager_link' => array(
          'variables' => array('text' => NULL, 'page_new' => NULL, 'element' => NULL, 'parameters' => array(), 'attributes' => array()),
        ),
        // from menu.inc
        'menu_link' => array(
          'render element' => 'element',
        ),
        'menu_tree' => array(
          'render element' => 'tree',
        ),
        'menu_local_task' => array(
          'render element' => 'element',
        ),
        'menu_local_action' => array(
          'render element' => 'element',
        ),
        'menu_local_tasks' => array(
          'variables' => array('primary' => array(), 'secondary' => array()),
        ),
        // from form.inc
        'select' => array(
          'render element' => 'element',
        ),
        'fieldset' => array(
          'render element' => 'element',
        ),
        'radio' => array(
          'render element' => 'element',
        ),
        'radios' => array(
          'render element' => 'element',
        ),
        'date' => array(
          'render element' => 'element',
        ),
        'exposed_filters' => array(
          'render element' => 'form',
        ),
        'checkbox' => array(
          'render element' => 'element',
        ),
        'checkboxes' => array(
          'render element' => 'element',
        ),
        'button' => array(
          'render element' => 'element',
        ),
        'image_button' => array(
          'render element' => 'element',
        ),
        'hidden' => array(
          'render element' => 'element',
        ),
        'textfield' => array(
          'render element' => 'element',
        ),
        'form' => array(
          'render element' => 'element',
        ),
        'textarea' => array(
          'render element' => 'element',
        ),
        'password' => array(
          'render element' => 'element',
        ),
        'file' => array(
          'render element' => 'element',
        ),
        'tableselect' => array(
          'render element' => 'element',
        ),
        'form_element' => array(
          'render element' => 'element',
        ),
        'form_required_marker' => array(
          'render element' => 'element',
        ),
        'form_element_label' => array(
          'render element' => 'element',
        ),
        'vertical_tabs' => array(
          'render element' => 'element',
        ),
        'container' => array(
          'render element' => 'element',
        ),
      );
    }
    
    /**
     * @ingroup schemaapi
     * @{
     */
    
    /**
     * Creates all tables in a module's hook_schema() implementation.
     *
     * Note: This function does not pass the module's schema through
     * hook_schema_alter(). The module's tables will be created exactly as the
     * module defines them.
     *
     * @param $module
     *   The module for which the tables will be created.
     */
    function drupal_install_schema($module) {
      $schema = drupal_get_schema_unprocessed($module);
      _drupal_schema_initialize($schema, $module, FALSE);
    
      foreach ($schema as $name => $table) {
        db_create_table($name, $table);
      }
    }
    
    /**
     * Remove all tables that a module defines in its hook_schema().
     *
     * Note: This function does not pass the module's schema through
     * hook_schema_alter(). The module's tables will be created exactly as the
     * module defines them.
     *
     * @param $module
     *   The module for which the tables will be removed.
     * @return
     *   An array of arrays with the following key/value pairs:
     *    - success: a boolean indicating whether the query succeeded.
     *    - query: the SQL query(s) executed, passed through check_plain().
     */
    function drupal_uninstall_schema($module) {
      $schema = drupal_get_schema_unprocessed($module);
      _drupal_schema_initialize($schema, $module, FALSE);
    
      foreach ($schema as $table) {
        if (db_table_exists($table['name'])) {
          db_drop_table($table['name']);
        }
      }
    }
    
    /**
     * Returns the unprocessed and unaltered version of a module's schema.
     *
     * Use this function only if you explicitly need the original
     * specification of a schema, as it was defined in a module's
     * hook_schema(). No additional default values will be set,
     * hook_schema_alter() is not invoked and these unprocessed
     * definitions won't be cached.
     *
     * This function can be used to retrieve a schema specification in
     * hook_schema(), so it allows you to derive your tables from existing
     * specifications.
     *
     * It is also used by drupal_install_schema() and
     * drupal_uninstall_schema() to ensure that a module's tables are
     * created exactly as specified without any changes introduced by a
     * module that implements hook_schema_alter().
     *
     * @param $module
     *   The module to which the table belongs.
     * @param $table
     *   The name of the table. If not given, the module's complete schema
     *   is returned.
     */
    function drupal_get_schema_unprocessed($module, $table = NULL) {
      // Load the .install file to get hook_schema.
      module_load_install($module);
      $schema = module_invoke($module, 'schema');
    
      if (isset($table) && isset($schema[$table])) {
        return $schema[$table];
      }
      elseif (!empty($schema)) {
        return $schema;
      }
      return array();
    }
    
    /**
     * Fill in required default values for table definitions returned by hook_schema().
     *
     * @param $schema
     *   The schema definition array as it was returned by the module's
     *   hook_schema().
     * @param $module
     *   The module for which hook_schema() was invoked.
     * @param $remove_descriptions
     *   (optional) Whether to additionally remove 'description' keys of all tables
     *   and fields to improve performance of serialize() and unserialize().
     *   Defaults to TRUE.
     */
    function _drupal_schema_initialize(&$schema, $module, $remove_descriptions = TRUE) {
      // Set the name and module key for all tables.
      foreach ($schema as $name => &$table) {
        if (empty($table['module'])) {
          $table['module'] = $module;
        }
        if (!isset($table['name'])) {
          $table['name'] = $name;
        }
        if ($remove_descriptions) {
          unset($table['description']);
          foreach ($table['fields'] as &$field) {
            unset($field['description']);
          }
        }
      }
    }
    
    /**
     * Retrieve a list of fields from a table schema. The list is suitable for use in a SQL query.
     *
     * @param $table
     *   The name of the table from which to retrieve fields.
     * @param
     *   An optional prefix to to all fields.
     *
     * @return An array of fields.
     **/
    function drupal_schema_fields_sql($table, $prefix = NULL) {
      $schema = drupal_get_schema($table);
      $fields = array_keys($schema['fields']);
      if ($prefix) {
        $columns = array();
        foreach ($fields as $field) {
          $columns[] = "$prefix.$field";
        }
        return $columns;
      }
      else {
        return $fields;
      }
    }
    
    /**
     * Saves (inserts or updates) a record to the database based upon the schema.
     *
     * @param $table
     *   The name of the table; this must be defined by a hook_schema()
     *   implementation.
     * @param $record
     *   An object or array representing the record to write, passed in by
     *   reference. If inserting a new record, values not provided in $record will
     *   be populated in $record and in the database with the default values from
     *   the schema, as well as a single serial (auto-increment) field (if present).
     *   If updating an existing record, only provided values are updated in the
     *   database, and $record is not modified.
     * @param $primary_keys
     *   To indicate that this is a new record to be inserted, omit this argument.
     *   If this is an update, this argument specifies the primary keys' field
     *   names. If there is only 1 field in the key, you may pass in a string; if
     *   there are multiple fields in the key, pass in an array.
     *
     * @return
     *   If the record insert or update failed, returns FALSE. If it succeeded,
     *   returns SAVED_NEW or SAVED_UPDATED, depending on the operation performed.
     */
    function drupal_write_record($table, &$record, $primary_keys = array()) {
      // Standardize $primary_keys to an array.
      if (is_string($primary_keys)) {
        $primary_keys = array($primary_keys);
      }
    
      $schema = drupal_get_schema($table);
      if (empty($schema)) {
        return FALSE;
      }
    
      $object = (object) $record;
      $fields = array();
    
      // Go through the schema to determine fields to write.
      foreach ($schema['fields'] as $field => $info) {
        if ($info['type'] == 'serial') {
          // Skip serial types if we are updating.
          if (!empty($primary_keys)) {
            continue;
          }
          // Track serial field so we can helpfully populate them after the query.
          // NOTE: Each table should come with one serial field only.
          $serial = $field;
        }
    
        // Skip field if it is in $primary_keys as it is unnecessary to update a
        // field to the value it is already set to.
        if (in_array($field, $primary_keys)) {
          continue;
        }
    
        if (!property_exists($object, $field)) {
          // Skip fields that are not provided, default values are already known
          // by the database.
          continue;
        }
    
        // Build array of fields to update or insert.
        if (empty($info['serialize'])) {
          $fields[$field] = $object->$field;
        }
        else {
          $fields[$field] = serialize($object->$field);
        }
    
        // Type cast to proper datatype, except when the value is NULL and the
        // column allows this.
        //
        // MySQL PDO silently casts e.g. FALSE and '' to 0 when inserting the value
        // into an integer column, but PostgreSQL PDO does not. Also type cast NULL
        // when the column does not allow this.
        if (isset($object->$field) || !empty($info['not null'])) {
          if ($info['type'] == 'int' || $info['type'] == 'serial') {
            $fields[$field] = (int) $fields[$field];
          }
          elseif ($info['type'] == 'float') {
            $fields[$field] = (float) $fields[$field];
          }
          else {
            $fields[$field] = (string) $fields[$field];
          }
        }
      }
    
      if (empty($fields)) {
        return;
      }
    
      // Build the SQL.
      if (empty($primary_keys)) {
        // We are doing an insert.
        $options = array('return' => Database::RETURN_INSERT_ID);
        if (isset($serial) && isset($fields[$serial])) {
          // If the serial column has been explicitly set with an ID, then we don't
          // require the database to return the last insert id.
          if ($fields[$serial]) {
            $options['return'] = Database::RETURN_AFFECTED;
          }
          // If a serial column does exist with no value (i.e. 0) then remove it as
          // the database will insert the correct value for us.
          else {
            unset($fields[$serial]);
          }
        }
        $query = db_insert($table, $options)->fields($fields);
        $return = SAVED_NEW;
      }
      else {
        $query = db_update($table)->fields($fields);
        foreach ($primary_keys as $key) {
          $query->condition($key, $object->$key);
        }
        $return = SAVED_UPDATED;
      }
    
      // Execute the SQL.
      if ($query_return = $query->execute()) {
        if (isset($serial)) {
          // If the database was not told to return the last insert id, it will be
          // because we already know it.
          if (isset($options) && $options['return'] != Database::RETURN_INSERT_ID) {
            $object->$serial = $fields[$serial];
          }
          else {
            $object->$serial = $query_return;
          }
        }
      }
      // If we have a single-field primary key but got no insert ID, the
      // query failed. Note that we explicitly check for FALSE, because
      // a valid update query which doesn't change any values will return
      // zero (0) affected rows.
      elseif ($query_return === FALSE && count($primary_keys) == 1) {
        $return = FALSE;
      }
    
      // If we are inserting, populate empty fields with default values.
      if (empty($primary_keys)) {
        foreach ($schema['fields'] as $field => $info) {
          if (isset($info['default']) && !property_exists($object, $field)) {
            $object->$field = $info['default'];
          }
        }
      }
    
      // If we began with an array, convert back.
      if (is_array($record)) {
        $record = (array) $object;
      }
    
      return $return;
    }
    
    /**
     * @} End of "ingroup schemaapi".
     */
    
    /**
     * Parses Drupal module and theme .info files.
     *
     * Info files are NOT for placing arbitrary theme and module-specific settings.
     * Use variable_get() and variable_set() for that.
     *
     * Information stored in a module .info file:
     * - name: The real name of the module for display purposes.
     * - description: A brief description of the module.
     * - dependencies: An array of shortnames of other modules this module requires.
     * - package: The name of the package of modules this module belongs to.
     *
     * See forum.info for an example of a module .info file.
     *
     * Information stored in a theme .info file:
     * - name: The real name of the theme for display purposes.
     * - description: Brief description.
     * - screenshot: Path to screenshot relative to the theme's .info file.
     * - engine: Theme engine; typically phptemplate.
     * - base: Name of a base theme, if applicable; e.g., base = zen.
     * - regions: Listed regions; e.g., region[left] = Left sidebar.
     * - features: Features available; e.g., features[] = logo.
     * - stylesheets: Theme stylesheets; e.g., stylesheets[all][] = my-style.css.
     * - scripts: Theme scripts; e.g., scripts[] = my-script.js.
     *
     * See bartik.info for an example of a theme .info file.
     *
     * @param $filename
     *   The file we are parsing. Accepts file with relative or absolute path.
     *
     * @return
     *   The info array.
     *
     * @see drupal_parse_info_format()
     */
    function drupal_parse_info_file($filename) {
      $info = &drupal_static(__FUNCTION__, array());
    
      if (!isset($info[$filename])) {
        if (!file_exists($filename)) {
          $info[$filename] = array();
        }
        else {
          $data = file_get_contents($filename);
          $info[$filename] = drupal_parse_info_format($data);
        }
      }
      return $info[$filename];
    }
    
    /**
     * Parse data in Drupal's .info format.
     *
     * Data should be in an .ini-like format to specify values. White-space
     * generally doesn't matter, except inside values:
     * @code
     *   key = value
     *   key = "value"
     *   key = 'value'
     *   key = "multi-line
     *   value"
     *   key = 'multi-line
     *   value'
     *   key
     *   =
     *   'value'
     * @endcode
     *
     * Arrays are created using a HTTP GET alike syntax:
     * @code
     *   key[] = "numeric array"
     *   key[index] = "associative array"
     *   key[index][] = "nested numeric array"
     *   key[index][index] = "nested associative array"
     * @endcode
     *
     * PHP constants are substituted in, but only when used as the entire value.
     * Comments should start with a semi-colon at the beginning of a line.
     *
     * @param $data
     *   A string to parse.
     * @return
     *   The info array.
     *
     * @see drupal_parse_info_file()
     */
    function drupal_parse_info_format($data) {
      $info = array();
      $constants = get_defined_constants();
    
      if (preg_match_all('
        @^\s*                           # Start at the beginning of a line, ignoring leading whitespace
        ((?:
          [^=;\[\]]|                    # Key names cannot contain equal signs, semi-colons or square brackets,
          \[[^\[\]]*\]                  # unless they are balanced and not nested
        )+?)
        \s*=\s*                         # Key/value pairs are separated by equal signs (ignoring white-space)
        (?:
          ("(?:[^"]|(?<=\\\\)")*")|     # Double-quoted string, which may contain slash-escaped quotes/slashes
          (\'(?:[^\']|(?<=\\\\)\')*\')| # Single-quoted string, which may contain slash-escaped quotes/slashes
          ([^\r\n]*?)                   # Non-quoted string
        )\s*$                           # Stop at the next end of a line, ignoring trailing whitespace
        @msx', $data, $matches, PREG_SET_ORDER)) {
        foreach ($matches as $match) {
          // Fetch the key and value string
          $i = 0;
          foreach (array('key', 'value1', 'value2', 'value3') as $var) {
            $$var = isset($match[++$i]) ? $match[$i] : '';
          }
          $value = stripslashes(substr($value1, 1, -1)) . stripslashes(substr($value2, 1, -1)) . $value3;
    
          // Parse array syntax
          $keys = preg_split('/\]?\[/', rtrim($key, ']'));
          $last = array_pop($keys);
          $parent = &$info;
    
          // Create nested arrays
          foreach ($keys as $key) {
            if ($key == '') {
              $key = count($parent);
            }
            if (!isset($parent[$key]) || !is_array($parent[$key])) {
              $parent[$key] = array();
            }
            $parent = &$parent[$key];
          }
    
          // Handle PHP constants.
          if (isset($constants[$value])) {
            $value = $constants[$value];
          }
    
          // Insert actual value
          if ($last == '') {
            $last = count($parent);
          }
          $parent[$last] = $value;
        }
      }
    
      return $info;
    }
    
    /**
     * Severity levels, as defined in RFC 3164: http://www.ietf.org/rfc/rfc3164.txt.
     *
     * @return
     *   Array of the possible severity levels for log messages.
     *
     * @see watchdog()
     * @ingroup logging_severity_levels
     */
    function watchdog_severity_levels() {
      return array(
        WATCHDOG_EMERGENCY   => t('emergency'),
        WATCHDOG_ALERT   => t('alert'),
        WATCHDOG_CRITICAL    => t('critical'),
        WATCHDOG_ERROR     => t('error'),
        WATCHDOG_WARNING => t('warning'),
        WATCHDOG_NOTICE  => t('notice'),
        WATCHDOG_INFO    => t('info'),
        WATCHDOG_DEBUG   => t('debug'),
      );
    }
    
    
    /**
     * Explode a string of given tags into an array.
     *
     * @see drupal_implode_tags()
     */
    function drupal_explode_tags($tags) {
      // This regexp allows the following types of user input:
      // this, "somecompany, llc", "and ""this"" w,o.rks", foo bar
      $regexp = '%(?:^|,\ *)("(?>[^"]*)(?>""[^"]* )*"|(?: [^",]*))%x';
      preg_match_all($regexp, $tags, $matches);
      $typed_tags = array_unique($matches[1]);
    
      $tags = array();
      foreach ($typed_tags as $tag) {
        // If a user has escaped a term (to demonstrate that it is a group,
        // or includes a comma or quote character), we remove the escape
        // formatting so to save the term into the database as the user intends.
        $tag = trim(str_replace('""', '"', preg_replace('/^"(.*)"$/', '\1', $tag)));
        if ($tag != "") {
          $tags[] = $tag;
        }
      }
    
      return $tags;
    }
    
    /**
     * Implode an array of tags into a string.
     *
     * @see drupal_explode_tags()
     */
    function drupal_implode_tags($tags) {
      $encoded_tags = array();
      foreach ($tags as $tag) {
        // Commas and quotes in tag names are special cases, so encode them.
        if (strpos($tag, ',') !== FALSE || strpos($tag, '"') !== FALSE) {
          $tag = '"' . str_replace('"', '""', $tag) . '"';
        }
    
        $encoded_tags[] = $tag;
      }
      return implode(', ', $encoded_tags);
    }
    
    /**
     * Flush all cached data on the site.
     *
     * Empties cache tables, rebuilds the menu cache and theme registries, and
     * invokes a hook so that other modules' cache data can be cleared as well.
     */
    function drupal_flush_all_caches() {
      // Change query-strings on css/js files to enforce reload for all users.
      _drupal_flush_css_js();
    
      registry_rebuild();
      drupal_clear_css_cache();
      drupal_clear_js_cache();
    
      // Rebuild the theme data. Note that the module data is rebuilt above, as
      // part of registry_rebuild().
      system_rebuild_theme_data();
      drupal_theme_rebuild();
    
      node_types_rebuild();
      // node_menu() defines menu items based on node types so it needs to come
      // after node types are rebuilt.
      menu_rebuild();
    
      // Synchronize to catch any actions that were added or removed.
      actions_synchronize();
    
      // Don't clear cache_form - in-progress form submissions may break.
      // Ordered so clearing the page cache will always be the last action.
      $core = array('cache', 'cache_filter', 'cache_bootstrap', 'cache_page');
      $cache_tables = array_merge(module_invoke_all('flush_caches'), $core);
      foreach ($cache_tables as $table) {
        cache_clear_all('*', $table, TRUE);
      }
    
      // Rebuild the bootstrap module list. We do this here so that developers
      // can get new hook_boot() implementations registered without having to
      // write a hook_update_N() function.
      _system_update_bootstrap_status();
    }
    
    /**
     * Helper function to change query-strings on css/js files.
     *
     * Changes the character added to all css/js files as dummy query-string, so
     * that all browsers are forced to reload fresh files.
     */
    function _drupal_flush_css_js() {
      // The timestamp is converted to base 36 in order to make it more compact.
      variable_set('css_js_query_string', base_convert(REQUEST_TIME, 10, 36));
    }
    
    /**
     * Debug function used for outputting debug information.
     *
     * The debug information is passed on to trigger_error() after being converted
     * to a string using _drupal_debug_message().
     *
     * @param $data
     *   Data to be output.
     * @param $label
     *   Label to prefix the data.
     * @param $print_r
     *   Flag to switch between print_r() and var_export() for data conversion to
     *   string. Set $print_r to TRUE when dealing with a recursive data structure
     *   as var_export() will generate an error.
     */
    function debug($data, $label = NULL, $print_r = FALSE) {
      // Print $data contents to string.
      $string = check_plain($print_r ? print_r($data, TRUE) : var_export($data, TRUE));
    
      // Display values with pre-formatting to increase readability.
      $string = '<pre>' . $string . '</pre>';
    
      trigger_error(trim($label ? "$label: $string" : $string));
    }
    
    /**
     * Parse a dependency for comparison by drupal_check_incompatibility().
     *
     * @param $dependency
     *   A dependency string, for example 'foo (>=8.x-4.5-beta5, 3.x)'.
     * @return
     *   An associative array with three keys:
     *   - 'name' includes the name of the thing to depend on (e.g. 'foo').
     *   - 'original_version' contains the original version string (which can be
     *     used in the UI for reporting incompatibilities).
     *   - 'versions' is a list of associative arrays, each containing the keys
     *     'op' and 'version'. 'op' can be one of: '=', '==', '!=', '<>', '<',
     *     '<=', '>', or '>='. 'version' is one piece like '4.5-beta3'.
     *   Callers should pass this structure to drupal_check_incompatibility().
     *
     * @see drupal_check_incompatibility()
     */
    function drupal_parse_dependency($dependency) {
      // We use named subpatterns and support every op that version_compare
      // supports. Also, op is optional and defaults to equals.
      $p_op = '(?P<operation>!=|==|=|<|<=|>|>=|<>)?';
      // Core version is always optional: 8.x-2.x and 2.x is treated the same.
      $p_core = '(?:' . preg_quote(DRUPAL_CORE_COMPATIBILITY) . '-)?';
      $p_major = '(?P<major>\d+)';
      // By setting the minor version to x, branches can be matched.
      $p_minor = '(?P<minor>(?:\d+|x)(?:-[A-Za-z]+\d+)?)';
      $value = array();
      $parts = explode('(', $dependency, 2);
      $value['name'] = trim($parts[0]);
      if (isset($parts[1])) {
        $value['original_version'] = ' (' . $parts[1];
        foreach (explode(',', $parts[1]) as $version) {
          if (preg_match("/^\s*$p_op\s*$p_core$p_major\.$p_minor/", $version, $matches)) {
            $op = !empty($matches['operation']) ? $matches['operation'] : '=';
            if ($matches['minor'] == 'x') {
              // Drupal considers "2.x" to mean any version that begins with
              // "2" (e.g. 2.0, 2.9 are all "2.x"). PHP's version_compare(),
              // on the other hand, treats "x" as a string; so to
              // version_compare(), "2.x" is considered less than 2.0. This
              // means that >=2.x and <2.x are handled by version_compare()
              // as we need, but > and <= are not.
              if ($op == '>' || $op == '<=') {
                $matches['major']++;
              }
              // Equivalence can be checked by adding two restrictions.
              if ($op == '=' || $op == '==') {
                $value['versions'][] = array('op' => '<', 'version' => ($matches['major'] + 1) . '.x');
                $op = '>=';
              }
            }
            $value['versions'][] = array('op' => $op, 'version' => $matches['major'] . '.' . $matches['minor']);
          }
        }
      }
      return $value;
    }
    
    /**
     * Check whether a version is compatible with a given dependency.
     *
     * @param $v
     *   The parsed dependency structure from drupal_parse_dependency().
     * @param $current_version
     *   The version to check against (like 4.2).
     * @return
     *   NULL if compatible, otherwise the original dependency version string that
     *   caused the incompatibility.
     *
     * @see drupal_parse_dependency()
     */
    function drupal_check_incompatibility($v, $current_version) {
      if (!empty($v['versions'])) {
        foreach ($v['versions'] as $required_version) {
          if ((isset($required_version['op']) && !version_compare($current_version, $required_version['version'], $required_version['op']))) {
            return $v['original_version'];
          }
        }
      }
    }
    
    /**
     * Get the entity info array of an entity type.
     *
     * @see hook_entity_info()
     * @see hook_entity_info_alter()
     *
     * @param $entity_type
     *   The entity type, e.g. node, for which the info shall be returned, or NULL
     *   to return an array with info about all types.
     */
    function entity_get_info($entity_type = NULL) {
      global $language;
    
      // Use the advanced drupal_static() pattern, since this is called very often.
      static $drupal_static_fast;
      if (!isset($drupal_static_fast)) {
        $drupal_static_fast['entity_info'] = &drupal_static(__FUNCTION__);
      }
      $entity_info = &$drupal_static_fast['entity_info'];
    
      // hook_entity_info() includes translated strings, so each language is cached
      // separately.
      $langcode = $language->language;
    
      if (empty($entity_info)) {
        if ($cache = cache_get("entity_info:$langcode")) {
          $entity_info = $cache->data;
        }
        else {
          $entity_info = module_invoke_all('entity_info');
          // Merge in default values.
          foreach ($entity_info as $name => $data) {
            $entity_info[$name] += array(
              'fieldable' => FALSE,
              'controller class' => 'DrupalDefaultEntityController',
              'static cache' => TRUE,
              'field cache' => TRUE,
              'load hook' => $name . '_load',
              'bundles' => array(),
              'view modes' => array(),
              'entity keys' => array(),
              'translation' => array(),
            );
            $entity_info[$name]['entity keys'] += array(
              'revision' => '',
              'bundle' => '',
            );
            foreach ($entity_info[$name]['view modes'] as $view_mode => $view_mode_info) {
              $entity_info[$name]['view modes'][$view_mode] += array(
                'custom settings' => FALSE,
              );
            }
            // If no bundle key is provided, assume a single bundle, named after
            // the entity type.
            if (empty($entity_info[$name]['entity keys']['bundle']) && empty($entity_info[$name]['bundles'])) {
              $entity_info[$name]['bundles'] = array($name => array('label' => $entity_info[$name]['label']));
            }
            // Prepare entity schema fields SQL info for
            // DrupalEntityControllerInterface::buildQuery().
            if (isset($entity_info[$name]['base table'])) {
              $entity_info[$name]['schema_fields_sql']['base table'] = drupal_schema_fields_sql($entity_info[$name]['base table']);
              if (isset($entity_info[$name]['revision table'])) {
                $entity_info[$name]['schema_fields_sql']['revision table'] = drupal_schema_fields_sql($entity_info[$name]['revision table']);
              }
            }
          }
          // Let other modules alter the entity info.
          drupal_alter('entity_info', $entity_info);
          cache_set("entity_info:$langcode", $entity_info);
        }
      }
    
      if (empty($entity_type)) {
        return $entity_info;
      }
      elseif (isset($entity_info[$entity_type])) {
        return $entity_info[$entity_type];
      }
    }
    
    /**
     * Resets the cached information about entity types.
     */
    function entity_info_cache_clear() {
      drupal_static_reset('entity_get_info');
      // Clear all languages.
      cache_clear_all('entity_info:', 'cache', TRUE);
    }
    
    /**
     * Helper function to extract id, vid, and bundle name from an entity.
     *
     * @param $entity_type
     *   The entity type; e.g. 'node' or 'user'.
     * @param $entity
     *   The entity from which to extract values.
     * @return
     *   A numerically indexed array (not a hash table) containing these
     *   elements:
     *   0: primary id of the entity
     *   1: revision id of the entity, or NULL if $entity_type is not versioned
     *   2: bundle name of the entity
     */
    function entity_extract_ids($entity_type, $entity) {
      $info = entity_get_info($entity_type);
      // Objects being created might not have id/vid yet.
      $id = isset($entity->{$info['entity keys']['id']}) ? $entity->{$info['entity keys']['id']} : NULL;
      $vid = ($info['entity keys']['revision'] && isset($entity->{$info['entity keys']['revision']})) ? $entity->{$info['entity keys']['revision']} : NULL;
      // If no bundle key provided, then we assume a single bundle, named after the
      // entity type.
      $bundle = $info['entity keys']['bundle'] ? $entity->{$info['entity keys']['bundle']} : $entity_type;
      return array($id, $vid, $bundle);
    }
    
    /**
     * Helper function to assemble an object structure with initial ids.
     *
     * This function can be seen as reciprocal to entity_extract_ids().
     *
     * @param $entity_type
     *   The entity type; e.g. 'node' or 'user'.
     * @param $ids
     *   A numerically indexed array, as returned by entity_extract_ids(),
     *   containing these elements:
     *   0: primary id of the entity
     *   1: revision id of the entity, or NULL if $entity_type is not versioned
     *   2: bundle name of the entity, or NULL if $entity_type has no bundles
     * @return
     *   An entity structure, initialized with the ids provided.
     */
    function entity_create_stub_entity($entity_type, $ids) {
      $entity = new stdClass();
      $info = entity_get_info($entity_type);
      $entity->{$info['entity keys']['id']} = $ids[0];
      if (!empty($info['entity keys']['revision']) && isset($ids[1])) {
        $entity->{$info['entity keys']['revision']} = $ids[1];
      }
      if (!empty($info['entity keys']['bundle']) && isset($ids[2])) {
        $entity->{$info['entity keys']['bundle']} = $ids[2];
      }
      return $entity;
    }
    
    /**
     * Load entities from the database.
     *
     * The entities are stored in a static memory cache, and will not require
     * database access if loaded again during the same page request.
     *
     * The actual loading is done through a class that has to implement the
     * DrupalEntityControllerInterface interface. By default,
     * DrupalDefaultEntityController is used. Entity types can specify that a
     * different class should be used by setting the 'controller class' key in
     * hook_entity_info(). These classes can either implement the
     * DrupalEntityControllerInterface interface, or, most commonly, extend the
     * DrupalDefaultEntityController class. See node_entity_info() and the
     * NodeController in node.module as an example.
     *
     * @see hook_entity_info()
     * @see DrupalEntityControllerInterface
     * @see DrupalDefaultEntityController
     * @see EntityFieldQuery
     *
     * @param $entity_type
     *   The entity type to load, e.g. node or user.
     * @param $ids
     *   An array of entity IDs, or FALSE to load all entities.
     * @param $conditions
     *   (deprecated) An associative array of conditions on the base table, where
     *   the keys are the database fields and the values are the values those
     *   fields must have. Instead, it is preferable to use EntityFieldQuery to
     *   retrieve a list of entity IDs loadable by this function.
     * @param $reset
     *   Whether to reset the internal cache for the requested entity type.
     *
     * @return
     *   An array of entity objects indexed by their ids. When no results are
     *   found, an empty array is returned.
     *
     * @todo Remove $conditions in Drupal 8.
     */
    function entity_load($entity_type, $ids = FALSE, $conditions = array(), $reset = FALSE) {
      if ($reset) {
        entity_get_controller($entity_type)->resetCache();
      }
      return entity_get_controller($entity_type)->load($ids, $conditions);
    }
    
    /**
     * Loads the unchanged, i.e. not modified, entity from the database.
     *
     * Unlike entity_load() this function ensures the entity is directly loaded from
     * the database, thus bypassing any static cache. In particular, this function
     * is useful to determine changes by comparing the entity being saved to the
     * stored entity.
     *
     * @param $entity_type
     *   The entity type to load, e.g. node or user.
     * @param $id
     *   The id of the entity to load.
     *
     * @return
     *   The unchanged entity, or FALSE if the entity cannot be loaded.
     */
    function entity_load_unchanged($entity_type, $id) {
      entity_get_controller($entity_type)->resetCache(array($id));
      $result = entity_get_controller($entity_type)->load(array($id));
      return reset($result);
    }
    
    /**
     * Get the entity controller class for an entity type.
     */
    function entity_get_controller($entity_type) {
      $controllers = &drupal_static(__FUNCTION__, array());
      if (!isset($controllers[$entity_type])) {
        $type_info = entity_get_info($entity_type);
        $class = $type_info['controller class'];
        $controllers[$entity_type] = new $class($entity_type);
      }
      return $controllers[$entity_type];
    }
    
    /**
     * Invoke hook_entity_prepare_view().
     *
     * If adding a new entity similar to nodes, comments or users, you should
     * invoke this function during the ENTITY_build_content() or
     * ENTITY_view_multiple() phases of rendering to allow other modules to alter
     * the objects during this phase. This is needed for situations where
     * information needs to be loaded outside of ENTITY_load() - particularly
     * when loading entities into one another - i.e. a user object into a node, due
     * to the potential for unwanted side-effects such as caching and infinite
     * recursion. By convention, entity_prepare_view() is called after
     * field_attach_prepare_view() to allow entity level hooks to act on content
     * loaded by field API.
     * @see hook_entity_prepare_view()
     *
     * @param $entity_type
     *   The type of entity, i.e. 'node', 'user'.
     * @param $entities
     *   The entity objects which are being prepared for view, keyed by object ID.
     * @param $langcode
     *   (optional) A language code to be used for rendering. Defaults to the global
     *   content language of the current request.
     */
    function entity_prepare_view($entity_type, $entities, $langcode = NULL) {
      if (!isset($langcode)) {
        $langcode = $GLOBALS['language_content']->language;
      }
    
      // To ensure hooks are only run once per entity, check for an
      // entity_view_prepared flag and only process items without it.
      // @todo: resolve this more generally for both entity and field level hooks.
      $prepare = array();
      foreach ($entities as $id => $entity) {
        if (empty($entity->entity_view_prepared)) {
          // Add this entity to the items to be prepared.
          $prepare[$id] = $entity;
    
          // Mark this item as prepared.
          $entity->entity_view_prepared = TRUE;
        }
      }
    
      if (!empty($prepare)) {
        module_invoke_all('entity_prepare_view', $prepare, $entity_type, $langcode);
      }
    }
    
    /**
     * Returns the uri elements of an entity.
     *
     * @param $entity_type
     *   The entity type; e.g. 'node' or 'user'.
     * @param $entity
     *   The entity for which to generate a path.
     * @return
     *   An array containing the 'path' and 'options' keys used to build the uri of
     *   the entity, and matching the signature of url(). NULL if the entity has no
     *   uri of its own.
     */
    function entity_uri($entity_type, $entity) {
      // This check enables the URI of an entity to be easily overridden from what
      // the callback for the entity type or bundle would return, and it helps
      // minimize performance overhead when entity_uri() is called multiple times
      // for the same entity.
      if (!isset($entity->uri)) {
        $info = entity_get_info($entity_type);
        list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);
    
        // A bundle-specific callback takes precedence over the generic one for the
        // entity type.
        if (isset($info['bundles'][$bundle]['uri callback'])) {
          $uri_callback = $info['bundles'][$bundle]['uri callback'];
        }
        elseif (isset($info['uri callback'])) {
          $uri_callback = $info['uri callback'];
        }
        else {
          $uri_callback = NULL;
        }
    
        // Invoke the callback to get the URI. If there is no callback, set the
        // entity's 'uri' property to FALSE to indicate that it is known to not have
        // a URI.
        if (isset($uri_callback) && function_exists($uri_callback)) {
          $entity->uri = $uri_callback($entity);
          if (!isset($entity->uri['options'])) {
            $entity->uri['options'] = array();
          }
          // Pass the entity data to url() so that alter functions do not need to
          // lookup this entity again.
          $entity->uri['options']['entity_type'] = $entity_type;
          $entity->uri['options']['entity'] = $entity;
        }
        else {
          $entity->uri = FALSE;
        }
      }
      return $entity->uri ? $entity->uri : NULL;
    }
    
    /**
     * Returns the label of an entity.
     *
     * See the 'label callback' component of the hook_entity_info() return value
     * for more information.
     *
     * @param $entity_type
     *   The entity type; e.g., 'node' or 'user'.
     * @param $entity
     *   The entity for which to generate the label.
     *
     * @return
     *   The entity label, or FALSE if not found.
     */
    function entity_label($entity_type, $entity) {
      $label = FALSE;
      $info = entity_get_info($entity_type);
      if (isset($info['label callback']) && function_exists($info['label callback'])) {
        $label = $info['label callback']($entity_type, $entity);
      }
      elseif (!empty($info['entity keys']['label']) && isset($entity->{$info['entity keys']['label']})) {
        $label = $entity->{$info['entity keys']['label']};
      }
    
      return $label;
    }
    
    /**
     * Helper function for attaching field API validation to entity forms.
     */
    function entity_form_field_validate($entity_type, $form, &$form_state) {
      // All field attach API functions act on an entity object, but during form
      // validation, we don't have one. $form_state contains the entity as it was
      // prior to processing the current form submission, and we must not update it
      // until we have fully validated the submitted input. Therefore, for
      // validation, act on a pseudo entity created out of the form values.
      $pseudo_entity = (object) $form_state['values'];
      field_attach_form_validate($entity_type, $pseudo_entity, $form, $form_state);
    }
    
    /**
     * Helper function for copying submitted values to entity properties for simple entity forms.
     *
     * During the submission handling of an entity form's "Save", "Preview", and
     * possibly other buttons, the form state's entity needs to be updated with the
     * submitted form values. Each entity form implements its own builder function
     * for doing this, appropriate for the particular entity and form, whereas
     * modules may specify additional builder functions in $form['#entity_builders']
     * for copying the form values of added form elements to entity properties.
     * Many of the main entity builder functions can call this helper function to
     * re-use its logic of copying $form_state['values'][PROPERTY] values to
     * $entity->PROPERTY for all entries in $form_state['values'] that are not field
     * data, and calling field_attach_submit() to copy field data. Apart from that
     * this helper invokes any additional builder functions that have been specified
     * in $form['#entity_builders'].
     *
     * For some entity forms (e.g., forms with complex non-field data and forms that
     * simultaneously edit multiple entities), this behavior may be inappropriate,
     * so the builder function for such forms needs to implement the required
     * functionality instead of calling this function.
     */
    function entity_form_submit_build_entity($entity_type, $entity, $form, &$form_state) {
      $info = entity_get_info($entity_type);
      list(, , $bundle) = entity_extract_ids($entity_type, $entity);
    
      // Copy top-level form values that are not for fields to entity properties,
      // without changing existing entity properties that are not being edited by
      // this form. Copying field values must be done using field_attach_submit().
      $values_excluding_fields = $info['fieldable'] ? array_diff_key($form_state['values'], field_info_instances($entity_type, $bundle)) : $form_state['values'];
      foreach ($values_excluding_fields as $key => $value) {
        $entity->$key = $value;
      }
    
      // Invoke all specified builders for copying form values to entity properties.
      if (isset($form['#entity_builders'])) {
        foreach ($form['#entity_builders'] as $function) {
          $function($entity_type, $entity, $form, $form_state);
        }
      }
    
      // Copy field values to the entity.
      if ($info['fieldable']) {
        field_attach_submit($entity_type, $entity, $form, $form_state);
      }
    }
    
    /**
     * Performs one or more XML-RPC request(s).
     *
     * Usage example:
     * @code
     * $result = xmlrpc('http://example.com/xmlrpc.php', array(
     *   'service.methodName' => array($parameter, $second, $third),
     * ));
     * @endcode
     *
     * @param $url
     *   An absolute URL of the XML-RPC endpoint.
     * @param $args
     *   An associative array whose keys are the methods to call and whose values
     *   are the arguments to pass to the respective method. If multiple methods
     *   are specified, a system.multicall is performed.
     * @param $options
     *   (optional) An array of options to pass along to drupal_http_request().
     *
     * @return
     *   For one request:
     *     Either the return value of the method on success, or FALSE.
     *     If FALSE is returned, see xmlrpc_errno() and xmlrpc_error_msg().
     *   For multiple requests:
     *     An array of results. Each result will either be the result
     *     returned by the method called, or an xmlrpc_error object if the call
     *     failed. See xmlrpc_error().
     */
    function xmlrpc($url, $args, $options = array()) {
      require_once DRUPAL_ROOT . '/includes/xmlrpc.inc';
      return _xmlrpc($url, $args, $options);
    }
    
    /**
     * Retrieves a list of all available archivers.
     *
     * @see hook_archiver_info()
     * @see hook_archiver_info_alter()
     */
    function archiver_get_info() {
      $archiver_info = &drupal_static(__FUNCTION__, array());
    
      if (empty($archiver_info)) {
        $cache = cache_get('archiver_info');
        if ($cache === FALSE) {
          // Rebuild the cache and save it.
          $archiver_info = module_invoke_all('archiver_info');
          drupal_alter('archiver_info', $archiver_info);
          uasort($archiver_info, 'drupal_sort_weight');
          cache_set('archiver_info', $archiver_info);
        }
        else {
          $archiver_info = $cache->data;
        }
      }
    
      return $archiver_info;
    }
    
    /**
     * Returns a string of supported archive extensions.
     *
     * @return
     *   A space-separated string of extensions suitable for use by the file
     *   validation system.
     */
    function archiver_get_extensions() {
      $valid_extensions = array();
      foreach (archiver_get_info() as $archive) {
        foreach ($archive['extensions'] as $extension) {
          foreach (explode('.', $extension) as $part) {
            if (!in_array($part, $valid_extensions)) {
              $valid_extensions[] = $part;
            }
          }
        }
      }
      return implode(' ', $valid_extensions);
    }
    
    /**
     * Create the appropriate archiver for the specified file.
     *
     * @param $file
     *   The full path of the archive file.  Note that stream wrapper
     *   paths are supported, but not remote ones.
     * @return
     *   A newly created instance of the archiver class appropriate
     *   for the specified file, already bound to that file.
     *   If no appropriate archiver class was found, will return FALSE.
     */
    function archiver_get_archiver($file) {
      // Archivers can only work on local paths
      $filepath = drupal_realpath($file);
      if (!is_file($filepath)) {
        throw new Exception(t('Archivers can only operate on local files: %file not supported', array('%file' => $file)));
      }
      $archiver_info = archiver_get_info();
    
      foreach ($archiver_info as $implementation) {
        foreach ($implementation['extensions'] as $extension) {
          // Because extensions may be multi-part, such as .tar.gz,
          // we cannot use simpler approaches like substr() or pathinfo().
          // This method isn't quite as clean but gets the job done.
          // Also note that the file may not yet exist, so we cannot rely
          // on fileinfo() or other disk-level utilities.
          if (strrpos($filepath, '.' . $extension) === strlen($filepath) - strlen('.' . $extension)) {
            return new $implementation['class']($filepath);
          }
        }
      }
    }
    
    /**
     * Drupal Updater registry.
     *
     * An Updater is a class that knows how to update various parts of the Drupal
     * file system, for example to update modules that have newer releases, or to
     * install a new theme.
     *
     * @return
     *   Returns the Drupal Updater class registry.
     *
     * @see hook_updater_info()
     * @see hook_updater_info_alter()
     */
    function drupal_get_updaters() {
      $updaters = &drupal_static(__FUNCTION__);
      if (!isset($updaters)) {
        $updaters = module_invoke_all('updater_info');
        drupal_alter('updater_info', $updaters);
        uasort($updaters, 'drupal_sort_weight');
      }
      return $updaters;
    }
    
    /**
     * Drupal FileTransfer registry.
     *
     * @return
     *   Returns the Drupal FileTransfer class registry.
     *
     * @see FileTransfer
     * @see hook_filetransfer_info()
     * @see hook_filetransfer_info_alter()
     */
    function drupal_get_filetransfer_info() {
      $info = &drupal_static(__FUNCTION__);
      if (!isset($info)) {
        // Since we have to manually set the 'file path' default for each
        // module separately, we can't use module_invoke_all().
        $info = array();
        foreach (module_implements('filetransfer_info') as $module) {
          $function = $module . '_filetransfer_info';
          if (function_exists($function)) {
            $result = $function();
            if (isset($result) && is_array($result)) {
              foreach ($result as &$values) {
                if (empty($values['file path'])) {
                  $values['file path'] = drupal_get_path('module', $module);
                }
              }
              $info = array_merge_recursive($info, $result);
            }
          }
        }
        drupal_alter('filetransfer_info', $info);
        uasort($info, 'drupal_sort_weight');
      }
      return $info;
    }