cdn.fallback.inc in CDN 6.2

Fallback when hook_file_url_alter() is not available (i.e. when the core patch is not installed or when not using a patched Drupal distribution): use the Parallel module's logic (with some adaptations to be able to use the CDN module's logic (in particular: cdn_file_url_alter()) to alter file URLs via the theme layer. Some of the functions are also used when altering rendered nodes so that their images are served from the CDN.

File

cdn.fallback.inc

<?php

/**
 * @file
 * Fallback when hook_file_url_alter() is not available (i.e. when the core
 * patch is not installed or when not using a patched Drupal distribution):
 * use the Parallel module's logic (with some adaptations to be able to use
 * the CDN module's logic (in particular: cdn_file_url_alter()) to alter file
 * URLs via the theme layer.
 * Some of the functions are also used when altering rendered nodes so that
 * their images are served from the CDN.
 */

/**
 * Implementation of hook_theme_registry_alter().
 *
 * Make CDN's page preprocess function run *after* everything else's, so that
 * a theme can't call drupal_get_js() and mess everything up.
 *
 * @param &$theme_registry
 *   The entire cache of theme registry information, post-processing.
 */
function _cdn_fallback_theme_registry_alter(&$theme_registry) {
  if (isset($theme_registry['page'])) {

    // If CDN's preprocess function is there already, remove it.
    if ($key = array_search('cdn_preprocess_page', $theme_registry['page']['preprocess functions'])) {
      unset($theme_registry['page']['preprocess functions'][$key]);
    }

    // Now tack it on at the end so it runs after everything else.
    $theme_registry['page']['preprocess functions'][] = 'cdn_preprocess_page';
  }
}

/**
 * Implementation of template_preprocess_page().
 */
function cdn_preprocess_page(&$variables) {

  // CSS.
  cdn_html_alter_css_urls($variables['styles']);

  // JS.
  cdn_html_alter_js_urls($variables['scripts']);
  cdn_html_alter_js_urls($variables['closure']);

  // Images.
  $skip_keys = array(
    'styles',
    'scripts',
    'zebra',
    'id',
    'directory',
    'layout',
    'head_title',
    'base_path',
    'front_page',
    'head',
    'body_classes',
  );
  foreach ($variables as $key => $value) {
    if (!in_array($key, $skip_keys) && is_string($value) && !empty($value)) {
      cdn_html_alter_image_urls($variables[$key]);
    }
  }
}

/**
 * Alter CSS file URLs in a piece of HTML.
 */
function cdn_html_alter_css_urls(&$html) {
  $url_prefix_regex = _cdn_generate_url_prefix_regex();
  $pattern = "#href=\"(({$url_prefix_regex})(.*?\\.css)(\\?.*)?)\"#";
  _cdn_html_alter_file_url($html, $pattern, 0, 3, 4, 'href="', '"');
}

/**
 * Alter JS file URLs in a piece of HTML.
 */
function cdn_html_alter_js_urls(&$html) {
  $url_prefix_regex = _cdn_generate_url_prefix_regex();
  $pattern = "#src=\"(({$url_prefix_regex})(.*?\\.js)(\\?.*)?)\"#";
  _cdn_html_alter_file_url($html, $pattern, 0, 3, 4, 'src="', '"');
}

/**
 * Alter image file URLs in a piece of HTML.
 */
function cdn_html_alter_image_urls(&$html) {
  $url_prefix_regex = _cdn_generate_url_prefix_regex();

  // TRICKY: order matters!
  // Image file URLs of <a> tags that wrap <img> tags.
  $pattern = "#((<a\\s+|<a\\s+[^>]*\\s+)href\\s*=\\s*[\"|'])({$url_prefix_regex})([^\"|^'|^\\?]*)()(\\?[^\"|^']*)?";
  $pattern .= "(";

  // Capture everything after the path.
  $pattern .= "([\"|'][^>]*)>";

  // End of opening <a> tag.
  $pattern .= "((<img\\s+|<img\\s+[^>]*\\s+)src\\s*=\\s*[\"|'])([^\"|^']*)([\"|'])";

  // Wrapped <img> tag.
  $pattern .= ")#i";
  _cdn_html_alter_file_url($html, $pattern, 0, 4, 5, 1, 7, 11);

  // Image file URLs in <img> tags.
  $pattern = "#((<img\\s+|<img\\s+[^>]*\\s+)src\\s*=\\s*[\"|'])({$url_prefix_regex})([^\"|^'|^\\?]*)()(\\?[^\"|^']*)?([\"|'])#i";
  _cdn_html_alter_file_url($html, $pattern, 0, 4, 5, 1, 7);
}

/**
 * Generate the URL prefix regular expression, that supports all possible
 * types of file URLs: root-relative, protocol-relative and absolute URLs.
 */
function _cdn_generate_url_prefix_regex() {
  global $base_url;
  static $url_prefix_regex;
  if (!isset($url_prefix_regex)) {
    $url_prefixes = array(
      preg_quote(base_path()) . '(?!/)',
      // Root-relative URL.
      // Note:  root-relative URL that isn't a protocol-relative URL. The
      // negative lookahead for a trailing slash is relaly only necessary
      // when this site is installed in the document root (i.e. when the base
      // path equals "/"), because this would otherwise match *all* protocol-
      // relative URLs, also those that already point to the CDN.
      preg_quote('//' . $_SERVER['HTTP_HOST'] . base_path()),
      // Protocol-relative URL.
      preg_quote($base_url . '/'),
    );
    $regexes = array();
    $farfuture = preg_quote('cdn/farfuture/');
    foreach ($url_prefixes as $url_prefix) {
      $regexes[] = $url_prefix . '(?!' . $farfuture . ')';
    }

    // The URL prefix regex that will match all URLs to the current site,
    // except for those that already point to Far Future expiration URLs.
    $url_prefix_regex = implode('|', $regexes);
  }
  return $url_prefix_regex;
}

/**
 * Alter the file URLs in a piece of HTML given a regexp pattern and some
 * additional parameters.
 *
 * @param &$html
 *   The HTML in which file URLs will be altered.
 * @param $pattern
 *   A regular expression pattern to apply to the subject.
 * @param $search_index
 *   The index of the search string in the array of regexp matches.
 * @param $path_index
 *   The index of the file path in the array of regexp matches.
 * @param $querystring_index
 *   The index of (an optional) query string in the array of regexp matches.
 * @param $prefix
 *   $search_index will be replaced by $prefix, plus the altered file URL,
 *   plus the @suffix. If numeric, then it is assumed to be the index of the
 *   prefix in the array of regexp matches.
 * @param $suffix
 *   See $prefix.
 * @param $comparison_index
 *   The index of a comparison path whose file extension should match the file
 *   extension of the path located at $path_index.
 */
function _cdn_html_alter_file_url(&$html, $pattern, $search_index, $path_index, $querystring_index, $prefix, $suffix, $comparison_index = FALSE) {

  // Find a match against the given pattern.
  preg_match_all($pattern, $html, $matches);

  // Generate replacements to alter file URLs.
  $searches = array();
  $replacements = array();
  for ($i = 0; $i < count($matches[0]); $i++) {
    $search = $matches[$search_index][$i];
    $path = $matches[$path_index][$i];
    $prefix_string = is_numeric($prefix) ? $matches[$prefix][$i] : $prefix;
    $suffix_string = is_numeric($suffix) ? $matches[$suffix][$i] : $suffix;

    // Compare the filename in the path with that of another index. The file
    // URL only is rewritten if it matches.
    if ($comparison_index) {
      $comparison = $matches[$comparison_index][$i];

      // Calculate length of extension.
      $path_ext_pos = strrpos($path, '.');
      $ext_length = -1 * (strlen($path) - $path_ext_pos);
      if (substr($path, $ext_length) !== substr($comparison, $ext_length)) {
        continue;
      }
    }

    // Store the current path as the old path, then let cdn_file_url_alter()
    // do its magic by invoking all file_url_alter hooks. When the path hasn't
    // changed and is not already root-relative or protocol-relative, then
    // generate a file URL as Drupal core would: prepend the base path.
    $old_path = $path;
    drupal_alter('file_url', $path);
    if ($path == $old_path && drupal_substr($path, 0, 1) != '/' && drupal_substr($path, 0, 2) != '//') {
      $path = base_path() . $path;
    }
    $searches[] = $search;
    $replacements[] = $prefix_string . $path . $matches[$querystring_index][$i] . $suffix_string;
  }

  // Apply the generated replacements ton the subject.
  $html = str_replace($searches, $replacements, $html);
}

Functions

Name	Description
cdn_html_alter_css_urls	Alter CSS file URLs in a piece of HTML.
cdn_html_alter_image_urls	Alter image file URLs in a piece of HTML.
cdn_html_alter_js_urls	Alter JS file URLs in a piece of HTML.
cdn_preprocess_page	Implementation of template_preprocess_page().
_cdn_fallback_theme_registry_alter	Implementation of hook_theme_registry_alter().
_cdn_generate_url_prefix_regex	Generate the URL prefix regular expression, that supports all possible types of file URLs: root-relative, protocol-relative and absolute URLs.
_cdn_html_alter_file_url	Alter the file URLs in a piece of HTML given a regexp pattern and some additional parameters.