Club Drupal

<?php

/**

 * @file

 * The theme system, which controls the output of Drupal.

 *

 * The theme system allows for nearly all output of the Drupal system to be

 * customized by user themes.

 */

/**

 * @defgroup content_flags Content markers

 * @{

 * Markers used by theme_mark() and node_mark() to designate content.

 * @see theme_mark(), node_mark()

 */

/**

 * Mark content as read.

 */

define('MARK_READ', 0);

/**

 * Mark content as being new.

 */

define('MARK_NEW', 1);

/**

 * Mark content as being updated.

 */

define('MARK_UPDATED', 2);

/**

 * @} End of "Content markers".

 */

/**

 * Determines if a theme is available to use.

 *

 * @param $theme

 *   Either the name of a theme or a full theme object.

 *

 * @return

 *   Boolean TRUE if the theme is enabled or is the site administration theme;

 *   FALSE otherwise.

 */

function drupal_theme_access($theme) {

  if (is_object($theme)) {

    return _drupal_theme_access($theme);

  }

  else {

    $themes = list_themes();

    return isset($themes[$theme]) && _drupal_theme_access($themes[$theme]);

  }

}

/**

 * Helper function for determining access to a theme.

 *

 * @see drupal_theme_access()

 */

function _drupal_theme_access($theme) {

  $admin_theme = variable_get('admin_theme');

  return !empty($theme->status) || ($admin_theme && $theme->name == $admin_theme);

}

/**

 * Initializes the theme system by loading the theme.

 */

function drupal_theme_initialize() {

  global $theme, $user, $theme_key;

  // If $theme is already set, assume the others are set, too, and do nothing

  if (isset($theme)) {

    return;

  }

  drupal_bootstrap(DRUPAL_BOOTSTRAP_DATABASE);

  $themes = list_themes();

  // Only select the user selected theme if it is available in the

  // list of themes that can be accessed.

  $theme = !empty($user->theme) && drupal_theme_access($user->theme) ? $user->theme : variable_get('theme_default', 'bartik');

  // Allow modules to override the theme. Validation has already been performed

  // inside menu_get_custom_theme(), so we do not need to check it again here.

  $custom_theme = menu_get_custom_theme();

  $theme = !empty($custom_theme) ? $custom_theme : $theme;

  // Store the identifier for retrieving theme settings with.

  $theme_key = $theme;

  // Find all our ancestor themes and put them in an array.

  $base_theme = array();

  $ancestor = $theme;

  while ($ancestor && isset($themes[$ancestor]->base_theme)) {

    $ancestor = $themes[$ancestor]->base_theme;

    $base_theme[] = $themes[$ancestor];

  }

  _drupal_theme_initialize($themes[$theme], array_reverse($base_theme));

  // Themes can have alter functions, so reset the drupal_alter() cache.

  drupal_static_reset('drupal_alter');

  // Provide the page with information about the theme that's used, so that a

  // later Ajax request can be rendered using the same theme.

  // @see ajax_base_page_theme()

  $setting['ajaxPageState'] = array(

    'theme' => $theme_key,

    'theme_token' => drupal_get_token($theme_key),

  );

  drupal_add_js($setting, 'setting');

}

/**

 * Initializes the theme system given already loaded information.

 *

 * This function is useful to initialize a theme when no database is present.

 *

 * @param $theme

 *   An object with the following information:

 *     filename

 *       The .info file for this theme. The 'path' to

 *       the theme will be in this file's directory. (Required)

 *     owner

 *       The path to the .theme file or the .engine file to load for

 *       the theme. (Required)

 *     stylesheet

 *       The primary stylesheet for the theme. (Optional)

 *     engine

 *       The name of theme engine to use. (Optional)

 * @param $base_theme

 *    An optional array of objects that represent the 'base theme' if the

 *    theme is meant to be derivative of another theme. It requires

 *    the same information as the $theme object. It should be in

 *    'oldest first' order, meaning the top level of the chain will

 *    be first.

 * @param $registry_callback

 *   The callback to invoke to set the theme registry.

 */

function _drupal_theme_initialize($theme, $base_theme = array(), $registry_callback = '_theme_load_registry') {

  global $theme_info, $base_theme_info, $theme_engine, $theme_path;

  $theme_info = $theme;

  $base_theme_info = $base_theme;

  $theme_path = dirname($theme->filename);

  // Prepare stylesheets from this theme as well as all ancestor themes.

  // We work it this way so that we can have child themes override parent

  // theme stylesheets easily.

  $final_stylesheets = array();

  // Grab stylesheets from base theme

  foreach ($base_theme as $base) {

    if (!empty($base->stylesheets)) {

      foreach ($base->stylesheets as $media => $stylesheets) {

        foreach ($stylesheets as $name => $stylesheet) {

          $final_stylesheets[$media][$name] = $stylesheet;

        }

      }

    }

  }

  // Add stylesheets used by this theme.

  if (!empty($theme->stylesheets)) {

    foreach ($theme->stylesheets as $media => $stylesheets) {

      foreach ($stylesheets as $name => $stylesheet) {

        $final_stylesheets[$media][$name] = $stylesheet;

      }

    }

  }

  // And now add the stylesheets properly

  foreach ($final_stylesheets as $media => $stylesheets) {

    foreach ($stylesheets as $stylesheet) {

      drupal_add_css($stylesheet, array('group' => CSS_THEME, 'every_page' => TRUE, 'media' => $media));

    }

  }

  // Do basically the same as the above for scripts

  $final_scripts = array();

  // Grab scripts from base theme

  foreach ($base_theme as $base) {

    if (!empty($base->scripts)) {

      foreach ($base->scripts as $name => $script) {

        $final_scripts[$name] = $script;

      }

    }

  }

  // Add scripts used by this theme.

  if (!empty($theme->scripts)) {

    foreach ($theme->scripts as $name => $script) {

      $final_scripts[$name] = $script;

    }

  }

  // Add scripts used by this theme.

  foreach ($final_scripts as $script) {

    drupal_add_js($script, array('group' => JS_THEME, 'every_page' => TRUE));

  }

  $theme_engine = NULL;

  // Initialize the theme.

  if (isset($theme->engine)) {

    // Include the engine.

    include_once DRUPAL_ROOT . '/' . $theme->owner;

    $theme_engine = $theme->engine;

    if (function_exists($theme_engine . '_init')) {

      foreach ($base_theme as $base) {

        call_user_func($theme_engine . '_init', $base);

      }

      call_user_func($theme_engine . '_init', $theme);

    }

  }

  else {

    // include non-engine theme files

    foreach ($base_theme as $base) {

      // Include the theme file or the engine.

      if (!empty($base->owner)) {

        include_once DRUPAL_ROOT . '/' . $base->owner;

      }

    }

    // and our theme gets one too.

    if (!empty($theme->owner)) {

      include_once DRUPAL_ROOT . '/' . $theme->owner;

    }

  }

  if (isset($registry_callback)) {

    _theme_registry_callback($registry_callback, array($theme, $base_theme, $theme_engine));

  }

}

/**

 * Gets the theme registry.

 *

 * @param $complete

 *   Optional boolean to indicate whether to return the complete theme registry

 *   array or an instance of the ThemeRegistry class. If TRUE, the complete

 *   theme registry array will be returned. This is useful if you want to

 *   foreach over the whole registry, use array_* functions or inspect it in a

 *   debugger. If FALSE, an instance of the ThemeRegistry class will be

 *   returned, this provides an ArrayObject which allows it to be accessed

 *   with array syntax and  isset(), and should be more lightweight

 *   than the full registry. Defaults to TRUE.

 *

 * @return

 *   The complete theme registry array, or an instance of the ThemeRegistry

 *   class.

 */

function theme_get_registry($complete = TRUE) {

  // Use the advanced drupal_static() pattern, since this is called very often.

  static $drupal_static_fast;

  if (!isset($drupal_static_fast)) {

    $drupal_static_fast['registry'] = &drupal_static('theme_get_registry');

  }

  $theme_registry = &$drupal_static_fast['registry'];

  // Initialize the theme, if this is called early in the bootstrap, or after

  // static variables have been reset.

  if (!is_array($theme_registry)) {

    drupal_theme_initialize();

    $theme_registry = array();

  }

  $key = (int) $complete;

  if (!isset($theme_registry[$key])) {

    list($callback, $arguments) = _theme_registry_callback();

    if (!$complete) {

      $arguments[] = FALSE;

    }

    $theme_registry[$key] = call_user_func_array($callback, $arguments);

  }

  return $theme_registry[$key];

}

/**

 * Sets the callback that will be used by theme_get_registry().

 *

 * @param $callback

 *   The name of the callback function.

 * @param $arguments

 *   The arguments to pass to the function.

 */

function _theme_registry_callback($callback = NULL, array $arguments = array()) {

  static $stored;

  if (isset($callback)) {

    $stored = array($callback, $arguments);

  }

  return $stored;

}

/**

 * Gets the theme_registry cache; if it doesn't exist, builds it.

 *

 * @param $theme

 *   The loaded $theme object as returned by list_themes().

 * @param $base_theme

 *   An array of loaded $theme objects representing the ancestor themes in

 *   oldest first order.

 * @param $theme_engine

 *   The name of the theme engine.

 * @param $complete

 *   Whether to load the complete theme registry or an instance of the

 *   ThemeRegistry class.

 *

 * @return

 *   The theme registry array, or an instance of the ThemeRegistry class.

 */

function _theme_load_registry($theme, $base_theme = NULL, $theme_engine = NULL, $complete = TRUE) {

  if ($complete) {

    // Check the theme registry cache; if it exists, use it.

    $cached = cache_get("theme_registry:$theme->name");

    if (isset($cached->data)) {

      $registry = $cached->data;

    }

    else {

      // If not, build one and cache it.

      $registry = _theme_build_registry($theme, $base_theme, $theme_engine);

      // Only persist this registry if all modules are loaded. This assures a

      // complete set of theme hooks.

      if (module_load_all(NULL)) {

        _theme_save_registry($theme, $registry);

      }

    }

    return $registry;

  }

  else {

    return new ThemeRegistry('theme_registry:runtime:' . $theme->name, 'cache');

  }

}

/**

 * Writes the theme_registry cache into the database.

 */

function _theme_save_registry($theme, $registry) {

  cache_set("theme_registry:$theme->name", $registry);

}

/**

 * Forces the system to rebuild the theme registry.

 *

 * This function should be called when modules are added to the system, or when

 * a dynamic system needs to add more theme hooks.

 */

function drupal_theme_rebuild() {

  drupal_static_reset('theme_get_registry');

  cache_clear_all('theme_registry', 'cache', TRUE);

}

/**

 * Builds the run-time theme registry.

 *

 * Extends DrupalCacheArray to allow the theme registry to be accessed as a

 * complete registry, while internally caching only the parts of the registry

 * that are actually in use on the site. On cache misses the complete

 * theme registry is loaded and used to update the run-time cache.

 */

class ThemeRegistry Extends DrupalCacheArray {

  /**

   * Whether the partial registry can be persisted to the cache.

   *

   * This is only allowed if all modules and the request method is GET. theme()

   * should be very rarely called on POST requests and this avoids polluting

   * the runtime cache.

   */

  protected $persistable;

  /**

   * The complete theme registry array.

   */

  protected $completeRegistry;

  function __construct($cid, $bin) {

    $this->cid = $cid;

    $this->bin = $bin;

    $this->persistable = module_load_all(NULL) && $_SERVER['REQUEST_METHOD'] == 'GET';

    $data = array();

    if ($this->persistable && $cached = cache_get($this->cid, $this->bin)) {

      $data = $cached->data;

    }

    else {

      // If there is no runtime cache stored, fetch the full theme registry,

      // but then initialize each value to NULL. This allows offsetExists()

      // to function correctly on non-registered theme hooks without triggering

      // a call to resolveCacheMiss().

      $data = $this->initializeRegistry();

      if ($this->persistable) {

        $this->set($data);

      }

    }

    $this->storage = $data;

  }

  /**

   * Initializes the full theme registry.

   *

   * @return

   *   An array with the keys of the full theme registry, but the values

   *   initialized to NULL.

   */

  function initializeRegistry() {

    $this->completeRegistry = theme_get_registry();

    return array_fill_keys(array_keys($this->completeRegistry), NULL);

  }

  public function offsetExists($offset) {

    // Since the theme registry allows for theme hooks to be requested that

    // are not registered, just check the existence of the key in the registry.

    // Use array_key_exists() here since a NULL value indicates that the theme

    // hook exists but has not yet been requested.

    return array_key_exists($offset, $this->storage);

  }

  public function offsetGet($offset) {

    // If the offset is set but empty, it is a registered theme hook that has

    // not yet been requested. Offsets that do not exist at all were not

    // registered in hook_theme().

    if (isset($this->storage[$offset])) {

      return $this->storage[$offset];

    }

    elseif (array_key_exists($offset, $this->storage)) {

      return $this->resolveCacheMiss($offset);

    }

  }

  public function resolveCacheMiss($offset) {

    if (!isset($this->completeRegistry)) {

      $this->completeRegistry = theme_get_registry();

    }

    $this->storage[$offset] = $this->completeRegistry[$offset];

    if ($this->persistable) {

      $this->persist($offset);

    }

    return $this->storage[$offset];

  }

  public function set($data, $lock = TRUE) {

    $lock_name = $this->cid . ':' . $this->bin;

    if (!$lock || lock_acquire($lock_name)) {

      if ($cached = cache_get($this->cid, $this->bin)) {

        // Use array merge instead of union so that filled in values in $data

        // overwrite empty values in the current cache.

        $data = array_merge($cached->data, $data);

      }

      else {

        $registry = $this->initializeRegistry();

        $data = array_merge($registry, $data);

      }

      cache_set($this->cid, $data, $this->bin);

      if ($lock) {

        lock_release($lock_name);

      }

    }

  }

}

/**

 * Process a single implementation of hook_theme().

 *

 * @param $cache

 *   The theme registry that will eventually be cached; It is an associative

 *   array keyed by theme hooks, whose values are associative arrays describing

 *   the hook:

 *   - 'type': The passed-in $type.

 *   - 'theme path': The passed-in $path.

 *   - 'function': The name of the function generating output for this theme

 *     hook. Either defined explicitly in hook_theme() or, if neither 'function'

 *     nor 'template' is defined, then the default theme function name is used.

 *     The default theme function name is the theme hook prefixed by either

 *     'theme_' for modules or '$name_' for everything else. If 'function' is

 *     defined, 'template' is not used.

 *   - 'template': The filename of the template generating output for this

 *     theme hook. The template is in the directory defined by the 'path' key of

 *     hook_theme() or defaults to $path.

 *   - 'variables': The variables for this theme hook as defined in

 *     hook_theme(). If there is more than one implementation and 'variables' is

 *     not specified in a later one, then the previous definition is kept.

 *   - 'render element': The renderable element for this theme hook as defined

 *     in hook_theme(). If there is more than one implementation and

 *     'render element' is not specified in a later one, then the previous

 *     definition is kept.

 *   - 'preprocess functions': See theme() for detailed documentation.

 *   - 'process functions': See theme() for detailed documentation.

 * @param $name

 *   The name of the module, theme engine, base theme engine, theme or base

 *   theme implementing hook_theme().

 * @param $type

 *   One of 'module', 'theme_engine', 'base_theme_engine', 'theme', or

 *   'base_theme'. Unlike regular hooks that can only be implemented by modules,

 *   each of these can implement hook_theme(). _theme_process_registry() is

 *   called in aforementioned order and new entries override older ones. For

 *   example, if a theme hook is both defined by a module and a theme, then the

 *   definition in the theme will be used.

 * @param $theme

 *   The loaded $theme object as returned from list_themes().

 * @param $path

 *   The directory where $name is. For example, modules/system or

 *   themes/bartik.

 *

 * @see theme()

 * @see _theme_build_registry()

 * @see hook_theme()

 * @see list_themes()

 */

function _theme_process_registry(&$cache, $name, $type, $theme, $path) {

  $result = array();

  // Processor functions work in two distinct phases with the process

  // functions always being executed after the preprocess functions.

  $variable_process_phases = array(

    'preprocess functions' => 'preprocess',

    'process functions'    => 'process',

  );

  $hook_defaults = array(

    'variables' => TRUE,

    'render element' => TRUE,

    'pattern' => TRUE,

    'base hook' => TRUE,

  );

  // Invoke the hook_theme() implementation, process what is returned, and

  // merge it into $cache.

  $function = $name . '_theme';

  if (function_exists($function)) {

    $result = $function($cache, $type, $theme, $path);

    foreach ($result as $hook => $info) {

      // When a theme or engine overrides a module's theme function

      // $result[$hook] will only contain key/value pairs for information being

      // overridden.  Pull the rest of the information from what was defined by

      // an earlier hook.

      // Fill in the type and path of the module, theme, or engine that

      // implements this theme function.

      $result[$hook]['type'] = $type;

      $result[$hook]['theme path'] = $path;

      // If function and file are omitted, default to standard naming

      // conventions.

      if (!isset($info['template']) && !isset($info['function'])) {

        $result[$hook]['function'] = ($type == 'module' ? 'theme_' : $name . '_') . $hook;

      }

      if (isset($cache[$hook]['includes'])) {

        $result[$hook]['includes'] = $cache[$hook]['includes'];

      }

      // If the theme implementation defines a file, then also use the path

      // that it defined. Otherwise use the default path. This allows

      // system.module to declare theme functions on behalf of core .include

      // files.

      if (isset($info['file'])) {

        $include_file = isset($info['path']) ? $info['path'] : $path;

        $include_file .= '/' . $info['file'];

        include_once DRUPAL_ROOT . '/' . $include_file;

        $result[$hook]['includes'][] = $include_file;

      }

      // If the default keys are not set, use the default values registered

      // by the module.

      if (isset($cache[$hook])) {

        $result[$hook] += array_intersect_key($cache[$hook], $hook_defaults);

      }

      // The following apply only to theming hooks implemented as templates.

      if (isset($info['template'])) {

        // Prepend the current theming path when none is set.

        if (!isset($info['path'])) {

          $result[$hook]['template'] = $path . '/' . $info['template'];

        }

      }

      // Allow variable processors for all theming hooks, whether the hook is

      // implemented as a template or as a function.

      foreach ($variable_process_phases as $phase_key => $phase) {

        // Check for existing variable processors. Ensure arrayness.

        if (!isset($info[$phase_key]) || !is_array($info[$phase_key])) {

          $info[$phase_key] = array();

          $prefixes = array();

          if ($type == 'module') {

            // Default variable processor prefix.

            $prefixes[] = 'template';

            // Add all modules so they can intervene with their own variable

            // processors. This allows them to provide variable processors even

            // if they are not the owner of the current hook.

            $prefixes += module_list();

          }

          elseif ($type == 'theme_engine' || $type == 'base_theme_engine') {

            // Theme engines get an extra set that come before the normally

            // named variable processors.

            $prefixes[] = $name . '_engine';

            // The theme engine registers on behalf of the theme using the

            // theme's name.

            $prefixes[] = $theme;

          }

          else {

            // This applies when the theme manually registers their own variable

            // processors.

            $prefixes[] = $name;

          }

          foreach ($prefixes as $prefix) {

            // Only use non-hook-specific variable processors for theming hooks

            // implemented as templates. See theme().

            if (isset($info['template']) && function_exists($prefix . '_' . $phase)) {

              $info[$phase_key][] = $prefix . '_' . $phase;

            }

            if (function_exists($prefix . '_' . $phase . '_' . $hook)) {

              $info[$phase_key][] = $prefix . '_' . $phase . '_' . $hook;

            }

          }

        }

        // Check for the override flag and prevent the cached variable

        // processors from being used. This allows themes or theme engines to

        // remove variable processors set earlier in the registry build.

        if (!empty($info['override ' . $phase_key])) {

          // Flag not needed inside the registry.

          unset($result[$hook]['override ' . $phase_key]);

        }

        elseif (isset($cache[$hook][$phase_key]) && is_array($cache[$hook][$phase_key])) {

          $info[$phase_key] = array_merge($cache[$hook][$phase_key], $info[$phase_key]);

        }

        $result[$hook][$phase_key] = $info[$phase_key];

      }

    }

    // Merge the newly created theme hooks into the existing cache.

    $cache = $result + $cache;

  }

  // Let themes have variable processors even if they didn't register a

  // template.

  if ($type == 'theme' || $type == 'base_theme') {

    foreach ($cache as $hook => $info) {

      // Check only if not registered by the theme or engine.

      if (empty($result[$hook])) {

        foreach ($variable_process_phases as $phase_key => $phase) {

          if (!isset($info[$phase_key])) {

            $cache[$hook][$phase_key] = array();

          }

          // Only use non-hook-specific variable processors for theming hooks

          // implemented as templates. See theme().

          if (isset($info['template']) && function_exists($name . '_' . $phase)) {

            $cache[$hook][$phase_key][] = $name . '_' . $phase;

          }

          if (function_exists($name . '_' . $phase . '_' . $hook)) {

            $cache[$hook][$phase_key][] = $name . '_' . $phase . '_' . $hook;

            $cache[$hook]['theme path'] = $path;

          }

          // Ensure uniqueness.

          $cache[$hook][$phase_key] = array_unique($cache[$hook][$phase_key]);

        }

      }

    }

  }

}

/**

 * Builds the theme registry cache.

 *

 * @param $theme

 *   The loaded $theme object as returned by list_themes().

 * @param $base_theme

 *   An array of loaded $theme objects representing the ancestor themes in

 *   oldest first order.

 * @param $theme_engine

 *   The name of the theme engine.

 */

function _theme_build_registry($theme, $base_theme, $theme_engine) {

  $cache = array();

  // First, process the theme hooks advertised by modules. This will

  // serve as the basic registry. Since the list of enabled modules is the same

  // regardless of the theme used, this is cached in its own entry to save

  // building it for every theme.

  if ($cached = cache_get('theme_registry:build:modules')) {

    $cache = $cached->data;

  }

  else {

    foreach (module_implements('theme') as $module) {

      _theme_process_registry($cache, $module, 'module', $module, drupal_get_path('module', $module));

    }

    // Only cache this registry if all modules are loaded.

    if (module_load_all(NULL)) {

      cache_set('theme_registry:build:modules', $cache);

    }

  }

  // Process each base theme.

  foreach ($base_theme as $base) {

    // If the base theme uses a theme engine, process its hooks.

    $base_path = dirname($base->filename);

    if ($theme_engine) {

      _theme_process_registry($cache, $theme_engine, 'base_theme_engine', $base->name, $base_path);

    }

    _theme_process_registry($cache, $base->name, 'base_theme', $base->name, $base_path);

  }

  // And then the same thing, but for the theme.

  if ($theme_engine) {

    _theme_process_registry($cache, $theme_engine, 'theme_engine', $theme->name, dirname($theme->filename));

  }

  // Finally, hooks provided by the theme itself.

  _theme_process_registry($cache, $theme->name, 'theme', $theme->name, dirname($theme->filename));

  // Let modules alter the registry.

  drupal_alter('theme_registry', $cache);

  // Optimize the registry to not have empty arrays for functions.

  foreach ($cache as $hook => $info) {

    foreach (array('preprocess functions', 'process functions') as $phase) {

      if (empty($info[$phase])) {

        unset($cache[$hook][$phase]);

      }

    }

  }

  return $cache;

}

/**

 * Returns a list of all currently available themes.

 *

 * Retrieved from the database, if available and the site is not in maintenance

 * mode; otherwise compiled freshly from the filesystem.

 *

 * @param $refresh

 *   Whether to reload the list of themes from the database. Defaults to FALSE.

 *

 * @return

 *   An associative array of the currently available themes. The keys are the

 *   themes' machine names and the values are objects having the following

 *   properties:

 *   - filename: The filepath and name of the .info file.

 *   - name: The machine name of the theme.

 *   - status: 1 for enabled, 0 for disabled themes.

 *   - info: The contents of the .info file.

 *   - stylesheets: A two dimensional array, using the first key for the

 *     media attribute (e.g. 'all'), the second for the name of the file

 *     (e.g. style.css). The value is a complete filepath (e.g.

 *     themes/bartik/style.css). Not set if no stylesheets are defined in the

 *     .info file.

 *   - scripts: An associative array of JavaScripts, using the filename as key

 *     and the complete filepath as value. Not set if no scripts are defined in

 *     the .info file.

 *   - prefix: The base theme engine prefix.

 *   - engine: The machine name of the theme engine.

 *   - base_theme: If this is a sub-theme, the machine name of the base theme

 *     defined in the .info file. Otherwise, the element is not set.

 *   - base_themes: If this is a sub-theme, an associative array of the

 *     base-theme ancestors of this theme, starting with this theme's base

 *     theme, then the base theme's own base theme, etc. Each entry has an

 *     array key equal to the theme's machine name, and a value equal to the

 *     human-readable theme name; if a theme with matching machine name does

 *     not exist in the system, the value will instead be NULL (and since the

 *     system would not know whether that theme itself has a base theme, that

 *     will end the array of base themes). This is not set if the theme is not

 *     a sub-theme.

 *   - sub_themes: An associative array of themes on the system that are

 *     either direct sub-themes (that is, they declare this theme to be

 *     their base theme), direct sub-themes of sub-themes, etc. The keys are

 *     the themes' machine names, and the values are the themes' human-readable

 *     names. This element is not set if there are no themes on the system that

 *     declare this theme as their base theme.

*/

function list_themes($refresh = FALSE) {

  $list = &drupal_static(__FUNCTION__, array());

  if ($refresh) {

    $list = array();

    system_list_reset();

  }

  if (empty($list)) {

    $list = array();

    $themes = array();

    // Extract from the database only when it is available.

    // Also check that the site is not in the middle of an install or update.

    if (!defined('MAINTENANCE_MODE')) {

      try {

        $themes = system_list('theme');

      }

      catch (Exception $e) {

        // If the database is not available, rebuild the theme data.

        $themes = _system_rebuild_theme_data();

      }

    }

    else {

      // Scan the installation when the database should not be read.

      $themes = _system_rebuild_theme_data();

    }

    foreach ($themes as $theme) {

      foreach ($theme->info['stylesheets'] as $media => $stylesheets) {

        foreach ($stylesheets as $stylesheet => $path) {

          $theme->stylesheets[$media][$stylesheet] = $path;

        }

      }

      foreach ($theme->info['scripts'] as $script => $path) {

        $theme->scripts[$script] = $path;

      }

      if (isset($theme->info['engine'])) {

        $theme->engine = $theme->info['engine'];

      }

      if (isset($theme->info['base theme'])) {

        $theme->base_theme = $theme->info['base theme'];

      }

      // Status is normally retrieved from the database. Add zero values when

      // read from the installation directory to prevent notices.

      if (!isset($theme->status)) {

        $theme->status = 0;

      }

      $list[$theme->name] = $theme;

    }

  }

  return $list;

}

/**

 * Find all the base themes for the specified theme.

 *

 * Themes can inherit templates and function implementations from earlier themes.

 *

 * @param $themes

 *   An array of available themes.

 * @param $key

 *   The name of the theme whose base we are looking for.

 * @param $used_keys

 *   A recursion parameter preventing endless loops.

 * @return

 *   Returns an array of all of the theme's ancestors; the first element's value

 *   will be NULL if an error occurred.

 */

function drupal_find_base_themes($themes, $key, $used_keys = array()) {

  $base_key = $themes[$key]->info['base theme'];

  // Does the base theme exist?

  if (!isset($themes[$base_key])) {

    return array($base_key => NULL);

  }

  $current_base_theme = array($base_key => $themes[$base_key]->info['name']);

  // Is the base theme itself a child of another theme?

  if (isset($themes[$base_key]->info['base theme'])) {

    // Do we already know the base themes of this theme?

    if (isset($themes[$base_key]->base_themes)) {

      return $themes[$base_key]->base_themes + $current_base_theme;

    }

    // Prevent loops.

    if (!empty($used_keys[$base_key])) {

      return array($base_key => NULL);

    }

    $used_keys[$base_key] = TRUE;

    return drupal_find_base_themes($themes, $base_key, $used_keys) + $current_base_theme;

  }

  // If we get here, then this is our parent theme.

  return $current_base_theme;

}

/**

 * Generates themed output.

 *

 * All requests for themed output must go through this function (however,

 * calling the theme() function directly is strongly discouraged - see next

 * paragraph). It examines the request and routes it to the appropriate

 * @link themeable theme function or template @endlink, by checking the theme

 * registry.

 *

 * Avoid calling this function directly. It is preferable to replace direct

 * calls to the theme() function with calls to drupal_render() by passing a

 * render array with a #theme key to drupal_render(), which in turn calls

 * theme().

 *

 * @section sec_theme_hooks Theme Hooks

 * Most commonly, the first argument to this function is the name of the theme

 * hook. For instance, to theme a taxonomy term, the theme hook name is

 * 'taxonomy_term'. Modules register theme hooks within a hook_theme()

 * implementation and provide a default implementation via a function named

 * theme_HOOK() (e.g., theme_taxonomy_term()) or via a template file named

 * according to the value of the 'template' key registered with the theme hook

 * (see hook_theme() for details). Default templates are implemented with the

 * PHPTemplate rendering engine and are named the same as the theme hook, with

 * underscores changed to hyphens, so for the 'taxonomy_term' theme hook, the

 * default template is 'taxonomy-term.tpl.php'.

 *

 * @subsection sub_overriding_theme_hooks Overriding Theme Hooks

 * Themes may also register new theme hooks within a hook_theme()

 * implementation, but it is more common for themes to override default

 * implementations provided by modules than to register entirely new theme

 * hooks. Themes can override a default implementation by implementing a

 * function named THEME_HOOK() (for example, the 'bartik' theme overrides the

 * default implementation of the 'menu_tree' theme hook by implementing a

 * bartik_menu_tree() function), or by adding a template file within its folder

 * structure that follows the template naming structure used by the theme's

 * rendering engine (for example, since the Bartik theme uses the PHPTemplate

 * rendering engine, it overrides the default implementation of the 'page' theme

 * hook by containing a 'page.tpl.php' file within its folder structure).

 *

 * @subsection sub_preprocess_templates Preprocessing for Template Files

 * If the implementation is a template file, several functions are called

 * before the template file is invoked, to modify the $variables array. These

 * fall into the "preprocessing" phase and the "processing" phase, and are

 * executed (if they exist), in the following order (note that in the following

 * list, HOOK indicates the theme hook name, MODULE indicates a module name,

 * THEME indicates a theme name, and ENGINE indicates a theme engine name):

 * - template_preprocess(&$variables, $hook): Creates a default set of

 *   variables for all theme hooks with template implementations.

 * - template_preprocess_HOOK(&$variables): Should be implemented by the module

 *   that registers the theme hook, to set up default variables.

 * - MODULE_preprocess(&$variables, $hook): hook_preprocess() is invoked on all

 *   implementing modules.

 * - MODULE_preprocess_HOOK(&$variables): hook_preprocess_HOOK() is invoked on

 *   all implementing modules, so that modules that didn't define the theme

 *   hook can alter the variables.

 * - ENGINE_engine_preprocess(&$variables, $hook): Allows the theme engine to

 *   set necessary variables for all theme hooks with template implementations.

 * - ENGINE_engine_preprocess_HOOK(&$variables): Allows the theme engine to set

 *   necessary variables for the particular theme hook.

 * - THEME_preprocess(&$variables, $hook): Allows the theme to set necessary

 *   variables for all theme hooks with template implementations.

 * - THEME_preprocess_HOOK(&$variables): Allows the theme to set necessary

 *   variables specific to the particular theme hook.

 * - template_process(&$variables, $hook): Creates an additional set of default

 *   variables for all theme hooks with template implementations. The variables

 *   created in this function are derived from ones created by

 *   template_preprocess(), but potentially altered by the other preprocess

 *   functions listed above. For example, any preprocess function can add to or

 *   modify the $variables['attributes_array'] variable, and after all of them

 *   have finished executing, template_process() flattens it into a

 *   $variables['attributes'] string for convenient use by templates.

 * - template_process_HOOK(&$variables): Should be implemented by the module

 *   that registers the theme hook, if it needs to perform additional variable

 *   processing after all preprocess functions have finished.

 * - MODULE_process(&$variables, $hook): hook_process() is invoked on all

 *   implementing modules.

 * - MODULE_process_HOOK(&$variables): hook_process_HOOK() is invoked on

 *   on all implementing modules, so that modules that didn't define the theme

 *   hook can alter the variables.

 * - ENGINE_engine_process(&$variables, $hook): Allows the theme engine to

 *   process variables for all theme hooks with template implementations.

 * - ENGINE_engine_process_HOOK(&$variables): Allows the theme engine to process

 *   the variables specific to the theme hook.

 * - THEME_process(&$variables, $hook):  Allows the theme to process the

 *   variables for all theme hooks with template implementations.

 * - THEME_process_HOOK(&$variables):  Allows the theme to process the

 *   variables specific to the theme hook.

 *

 * @subsection sub_preprocess_theme_funcs Preprocessing for Theme Functions

 * If the implementation is a function, only the theme-hook-specific preprocess

 * and process functions (the ones ending in _HOOK) are called from the

 * list above. This is because theme hooks with function implementations

 * need to be fast, and calling the non-theme-hook-specific preprocess and

 * process functions for them would incur a noticeable performance penalty.

 *

 * @subsection sub_alternate_suggestions Suggesting Alternate Hooks

 * There are two special variables that these preprocess and process functions

 * can set: 'theme_hook_suggestion' and 'theme_hook_suggestions'. These will be

 * merged together to form a list of 'suggested' alternate theme hooks to use,

 * in reverse order of priority. theme_hook_suggestion will always be a higher

 * priority than items in theme_hook_suggestions. theme() will use the

 * highest priority implementation that exists. If none exists, theme() will

 * use the implementation for the theme hook it was called with. These

 * suggestions are similar to and are used for similar reasons as calling

 * theme() with an array as the $hook parameter (see below). The difference

 * is whether the suggestions are determined by the code that calls theme() or

 * by a preprocess or process function.

 *

 * @param $hook

 *   The name of the theme hook to call. If the name contains a

 *   double-underscore ('__') and there isn't an implementation for the full

 *   name, the part before the '__' is checked. This allows a fallback to a

 *   more generic implementation. For example, if theme('links__node', ...) is

 *   called, but there is no implementation of that theme hook, then the

 *   'links' implementation is used. This process is iterative, so if

 *   theme('links__contextual__node', ...) is called, theme() checks for the

 *   following implementations, and uses the first one that exists:

 *   - links__contextual__node

 *   - links__contextual

 *   - links

 *   This allows themes to create specific theme implementations for named

 *   objects and contexts of otherwise generic theme hooks. The $hook parameter

 *   may also be an array, in which case the first theme hook that has an

 *   implementation is used. This allows for the code that calls theme() to

 *   explicitly specify the fallback order in a situation where using the '__'

 *   convention is not desired or is insufficient.

 * @param $variables

 *   An associative array of variables to merge with defaults from the theme

 *   registry, pass to preprocess and process functions for modification, and

 *   finally, pass to the function or template implementing the theme hook.

 *   Alternatively, this can be a renderable array, in which case, its

 *   properties are mapped to variables expected by the theme hook

 *   implementations.

 *

 * @return

 *   An HTML string representing the themed output.

 *

 * @see drupal_render()

 * @see themeable

 * @see hook_theme()

 * @see template_preprocess()

 * @see template_process()

 */

function theme($hook, $variables = array()) {

  // If called before all modules are loaded, we do not necessarily have a full

  // theme registry to work with, and therefore cannot process the theme

  // request properly. See also _theme_load_registry().

  if (!module_load_all(NULL) && !defined('MAINTENANCE_MODE')) {

    throw new Exception(t('theme() may not be called until all modules are loaded.'));

  }

  $hooks = theme_get_registry(FALSE);

  // If an array of hook candidates were passed, use the first one that has an

  // implementation.

  if (is_array($hook)) {

    foreach ($hook as $candidate) {

      if (isset($hooks[$candidate])) {

        break;

      }

    }

    $hook = $candidate;

  }

  // If there's no implementation, check for more generic fallbacks. If there's

  // still no implementation, log an error and return an empty string.

  if (!isset($hooks[$hook])) {

    // Iteratively strip everything after the last '__' delimiter, until an

    // implementation is found.

    while ($pos = strrpos($hook, '__')) {

      $hook = substr($hook, 0, $pos);

      if (isset($hooks[$hook])) {

        break;

      }

    }

    if (!isset($hooks[$hook])) {

      // Only log a message when not trying theme suggestions ($hook being an

      // array).

      if (!isset($candidate)) {

        watchdog('theme', 'Theme hook %hook not found.', array('%hook' => $hook), WATCHDOG_WARNING);

      }

      return '';

    }

  }

  $info = $hooks[$hook];

  global $theme_path;

  $temp = $theme_path;

  // point path_to_theme() to the currently used theme path:

  $theme_path = $info['theme path'];

  // Include a file if the theme function or variable processor is held

  // elsewhere.

  if (!empty($info['includes'])) {

    foreach ($info['includes'] as $include_file) {

      include_once DRUPAL_ROOT . '/' . $include_file;

    }

  }

  // If a renderable array is passed as $variables, then set $variables to

  // the arguments expected by the theme function.

  if (isset($variables['#theme']) || isset($variables['#theme_wrappers'])) {

    $element = $variables;

    $variables = array();

    if (isset($info['variables'])) {

      foreach (array_keys($info['variables']) as $name) {

        if (isset($element["#$name"])) {

          $variables[$name] = $element["#$name"];

        }

      }

    }

    else {

      $variables[$info['render element']] = $element;

    }

  }

  // Merge in argument defaults.

  if (!empty($info['variables'])) {

    $variables += $info['variables'];

  }

  elseif (!empty($info['render element'])) {

    $variables += array($info['render element'] => array());

  }

  // Invoke the variable processors, if any. The processors may specify

  // alternate suggestions for which hook's template/function to use. If the

  // hook is a suggestion of a base hook, invoke the variable processors of

  // the base hook, but retain the suggestion as a high priority suggestion to

  // be used unless overridden by a variable processor function.

  if (isset($info['base hook'])) {

    $base_hook = $info['base hook'];

    $base_hook_info = $hooks[$base_hook];

    // Include files required by the base hook, since its variable processors

    // might reside there.

    if (!empty($base_hook_info['includes'])) {

      foreach ($base_hook_info['includes'] as $include_file) {

        include_once DRUPAL_ROOT . '/' . $include_file;

      }

    }

    if (isset($base_hook_info['preprocess functions']) || isset($base_hook_info['process functions'])) {

      $variables['theme_hook_suggestion'] = $hook;

      $hook = $base_hook;

      $info = $base_hook_info;

    }

  }

  if (isset($info['preprocess functions']) || isset($info['process functions'])) {

    $variables['theme_hook_suggestions'] = array();

    foreach (array('preprocess functions', 'process functions') as $phase) {

      if (!empty($info[$phase])) {

        foreach ($info[$phase] as $processor_function) {

          if (function_exists($processor_function)) {

            // We don't want a poorly behaved process function changing $hook.

            $hook_clone = $hook;

            $processor_function($variables, $hook_clone);

          }

        }

      }