Have array expert look at hook_registry_alter

advanced_forum_theme_registry_alter() goes through a lot of crazy array manipulations to convince core that the various styles directories are part of the theme. It works, but I can't help but think it could be simpler. I'm not very good with arrays and there's a very good chance this code could be condensed by someone with more of a clue. So I'm putting this issue out there hoping someone with said clue about arrays will take a look and tell me if it could be made simpler.

For quick reference, here's the code:

  // --- The following section manipulates the theme registry so the .tpl files
  // --- for the given templates can be found first in the (sub)theme directory
  // --- then in ancestor themes, if any, then in the active style directory
  // --- for advanced forum or any ancestor styles.

  // Affected templates
  $templates = array('node',
                     'comment',
                     'comment_wrapper',
                     'forums',
                     'forum_list',
                     'forum_topic_list',
                     'forum_icon',
                     'forum_submitted',
                     'author_pane',
                     'advanced_forum_statistics',
                     'advanced_forum_search_forum',
                     'advanced_forum_search_topic',
                     'advanced_forum_topic_list_view',
                     'views_view_fields__advanced_forum_search',
                     'views_view_fields__advanced_forum_search_topic',
                     'views_view_forum_topic_list__advanced_forum_topic_list',
                     'views_view__advanced_forum_topic_list',
                     'views_view__advanced_forum_topic_list',
                     'advanced_forum_topic_legend',
                     'advanced_forum_forum_legend',
                     'advanced_forum_topic_header',
                );

  // Find all our ancestor themes and put them in an array.
  global $theme;
  $themes = list_themes();

  $ancestor_paths = array();
  $ancestor = $theme;
  while ($ancestor && isset($themes[$ancestor]->base_theme)) {
    array_unshift($ancestor_paths, dirname($themes[$themes[$ancestor]->base_theme]->filename));
    $ancestor = $themes[$ancestor]->base_theme;
  }

  // Get the sequence of styles to look in for templates
  $lineage = advanced_forum_style_lineage();
  
  if (!array_key_exists('naked', $lineage)) {
    // Add naked in at the end of the line to prevent problems if a style 
    // doesn't include all needed templates.
    $lineage['naked'] = drupal_get_path('module', 'advanced_forum') . '/styles/naked';   
  }
  
  foreach ($templates as $template) {
    // Sanity check in case the template is not being used.
    if (!empty($theme_registry[$template])) {

      // If there was a path in there, store it.
      $existing_path = array_shift($theme_registry[$template]['theme paths']);

      // Add paths for our style and ancestors before the existing path, if any.
      foreach ($lineage AS $style => $style_path) { 
        array_unshift($theme_registry[$template]['theme paths'], $existing_path, $style_path);
        $existing_path = array_shift($theme_registry[$template]['theme paths']);
      }
 
      // If there are any ancestor paths (ie: we are in a subtheme, add those)
      foreach ($ancestor_paths as $ancestor_path) {
        $theme_registry[$template]['theme paths'][] = $ancestor_path;
      }

      // Put the active theme's path last since that takes precidence.
      $theme_registry[$template]['theme paths'][] = advanced_forum_path_to_theme();
    }
  }