drupal/includes/theme.inc

<?php
// $Id$

/**
 * @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.
 *
 * @ingroup themeable
 */

/**
 * @name 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 $theme
 *   An object representing the theme to check.
 * @return
 *   Boolean TRUE if the theme is enabled or is the site administration theme;
 *   FALSE otherwise.
 */
function drupal_theme_access($theme) {
  $admin_theme = variable_get('admin_theme');
  return !empty($theme->status) || ($admin_theme && $theme->name == $admin_theme);
}

/**
 * Initialize 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) && isset($themes[$user->theme]) && drupal_theme_access($themes[$user->theme]) ? $user->theme : variable_get('theme_default', 'garland');

  // Allow modules to override the present theme... only select custom theme
  // if it is available in the list of themes that can be accessed.
  $custom_theme = menu_get_custom_theme();
  $theme = $custom_theme && isset($themes[$custom_theme]) && drupal_theme_access($themes[$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)) {
    $base_theme[] = $new_base_theme = $themes[$themes[$ancestor]->base_theme];
    $ancestor = $themes[$ancestor]->base_theme;
  }
  _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');
}

/**
 * Initialize 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('weight' => CSS_THEME, '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('weight' => JS_THEME));
  }

  $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 (function_exists($registry_callback)) {
    $registry_callback($theme, $base_theme, $theme_engine);
  }
}

/**
 * Get the theme registry.
 * @return
 *   The theme registry array if it has been stored in memory, NULL otherwise.
 */
function theme_get_registry() {
  return _theme_set_registry();
}

/**
 * Store the theme registry in memory.
 * @param $registry
 *   A registry array as returned by _theme_build_registry()
 * @return
 *   The theme registry array stored in memory
 */
function _theme_set_registry($registry = NULL) {
  static $theme_registry = NULL;

  if (isset($registry)) {
    $theme_registry = $registry;
  }

  return $theme_registry;
}

/**
 * Get the theme_registry cache from the database; if it doesn't exist, build it.
 *
 * @param $theme
 *   The loaded $theme object as returned by list_themes().
 * @param $base_theme
 *   An array of loaded $theme objects representing the ancestor themes in
 *   oldest first order.
 * @param theme_engine
 *   The name of the theme engine.
 */
function _theme_load_registry($theme, $base_theme = NULL, $theme_engine = NULL) {
  // Check the theme registry cache; if it exists, use it.
  $cache = cache_get("theme_registry:$theme->name", 'cache');
  if (isset($cache->data)) {
    $registry = $cache->data;
    _theme_set_registry($registry);
  }
  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, $registry);
      _theme_set_registry($registry);
    }
  }
}

/**
 * Write the theme_registry cache into the database.
 */
function _theme_save_registry($theme, $registry) {
  cache_set("theme_registry:$theme->name", $registry);
}

/**
 * Force the system to rebuild the theme registry; this 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() {
  cache_clear_all('theme_registry', 'cache', TRUE);
}

/**
 * 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.
 *   - 'theme paths': The paths where implementations of a theme hook can be
 *     found. Its definition is similarly inherited like 'variables'. Each time
 *     _theme_process_registry() is called for this theme hook, either the
 *     'path' key from hook_theme() (if defined) or $path is added.
 *   - '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 $name is. For example, modules/system or
 *   themes/garland.
 *
 * @see theme()
 * @see _theme_process_registry()
 * @see hook_theme()
 * @see list_themes()
 */
function _theme_process_registry(&$cache, $name, $type, $theme, $path) {
  $result = array();
  $function = $name . '_theme';

  // 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',
  );

  if (function_exists($function)) {
    $result = $function($cache, $type, $theme, $path);
    foreach ($result as $hook => $info) {
      $result[$hook]['type'] = $type;
      $result[$hook]['theme path'] = $path;
      // if function and file are left out, default to standard naming
      // conventions.
      if (!isset($info['template']) && !isset($info['function'])) {
        $result[$hook]['function'] = ($type == 'module' ? 'theme_' : $name . '_') . $hook;
      }
      // If a path is set in the info, use what was set. Otherwise use the
      // default path. This is mostly so system.module can declare theme
      // functions on behalf of core .include files.
      // All files are included to be safe. Conditionally included
      // files can prevent them from getting registered.
      if (isset($cache[$hook]['includes'])) {
        $result[$hook]['includes'] = $cache[$hook]['includes'];
      }
      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 'variables' have been defined previously, carry them forward.
      // This should happen if a theme overrides a Drupal defined theme
      // function, for example.
      if (!isset($info['variables']) && isset($cache[$hook]['variables'])) {
        $result[$hook]['variables'] = $cache[$hook]['variables'];
      }
      // Same for 'render element'.
      if (!isset($info['render element']) && isset($cache[$hook]['render element'])) {
        $result[$hook]['render element'] = $cache[$hook]['render element'];
      }

      // 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'];
        }

        // These are used for template naming suggestions. Theme implementations
        // can occur in multiple paths. Suggestions should follow.
        if (!isset($info['theme paths']) && isset($cache[$hook])) {
          $result[$hook]['theme paths'] = $cache[$hook]['theme paths'];
        }
        // Check for sub-directories.
        $result[$hook]['theme paths'][] = isset($info['path']) ? $info['path'] : $path;
      }

      // 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.
    $cache = array_merge($cache, $result);
  }

  // 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;
          }
          // Ensure uniqueness.
          $cache[$hook][$phase_key] = array_unique($cache[$hook][$phase_key]);
        }
      }
    }
  }
}

/**
 * Rebuild 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.
  foreach (module_implements('theme') as $module) {
    _theme_process_registry($cache, $module, 'module', $module, drupal_get_path('module', $module));
  }

  // 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;
}

/**
 * Return 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 $refresh
 *   Whether to reload the list of themes from the database. Defaults to FALSE.
 * @return
 *   An associative array of the currently available themes. The keys are the
 *   names of the themes and the values are objects having the following
 *   properties:
 *   - 'filename': The name of the .info file.
 *   - 'name': The name of the theme.
 *   - 'status': 1 for enabled, 0 for disabled themes.
 *   - 'info': The contents of the .info file.
 *   - 'stylesheets': A two dimensional array, using the first key for the
 *     'media' attribute (e.g. 'all'), the second for the name of the file
 *     (e.g. style.css). The value is a complete filepath
 *     (e.g. themes/garland/style.css).
 *   - 'scripts': An associative array of JavaScripts, using the filename as key
 *     and the complete filepath as value.
 *   - 'engine': The name of the theme engine.
 *   - 'base theme': The name of the base theme.
 */
function list_themes($refresh = FALSE) {
  static $list = array();

  if ($refresh) {
    $list = array();
    drupal_static_reset('system_list');
  }

  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 (db_is_active() && !defined('MAINTENANCE_MODE')) {
      foreach (system_list('theme') as $theme) {
        if (file_exists($theme->filename)) {
          $theme->info = unserialize($theme->info);
          $themes[] = $theme;
        }
      }
    }
    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 => $path) {
        if (file_exists($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;
}

/**
 * Generate the themed output.
 *
 * All requests for theme hooks must go through this function. It examines
 * the request and routes it to the appropriate theme function. The theme
 * registry is checked to determine which implementation to use, which may
 * be a function or a template.
 *
 * If the implementation is a template, the following functions may be used to
 * modify the $variables array. They are processed in two distinct phases;
 * "preprocess" and "process" functions. The order listed here is the order in
 * which they execute.
 *
 * - template_preprocess(&$variables)
 *   This sets a default set of variables for all template implementations.
 *
 * - template_preprocess_HOOK(&$variables)
 *   This is the first preprocessor called specific to the hook; it should be
 *   implemented by the module that registers it.
 *
 * - MODULE_preprocess(&$variables)
 *   This will be called for all templates; it should only be used if there
 *   is a real need. It's purpose is similar to template_preprocess().
 *
 * - MODULE_preprocess_HOOK(&$variables)
 *   This is for modules that want to alter or provide extra variables for
 *   theming hooks not registered to itself. For example, if a module named
 *   "foo" wanted to alter the $classes_array variable for the hook "node" a
 *   preprocess function of foo_preprocess_node() can be created to intercept
 *   and alter the variable.
 *
 * - ENGINE_engine_preprocess(&$variables)
 *   This function should only be implemented by theme engines and exists
 *   so that it can set necessary variables for all hooks.
 *
 * - ENGINE_engine_preprocess_HOOK(&$variables)
 *   This is the same as the previous function, but it is called for a single
 *   theming hook.
 *
 * - THEME_preprocess(&$variables)
 *   This is for themes that want to alter or provide extra variables. For
 *   example, if a theme named "foo" wanted to alter the $classes_array variable
 *   for the hook "node" a preprocess function of foo_preprocess_node() can be
 *   created to intercept and alter the variable.
 *
 * - THEME_preprocess_HOOK(&$variables)
 *   The same applies from the previous function, but it is called for a
 *   specific hook.
 *
 * - template_process(&$variables)
 *   This sets a default set of variables for all template implementations.
 *
 * - template_process_HOOK(&$variables)
 *   This is the first processor called specific to the hook; it should be
 *   implemented by the module that registers it.
 *
 * - MODULE_process(&$variables)
 *   This will be called for all templates; it should only be used if there
 *   is a real need. It's purpose is similar to template_process().
 *
 * - MODULE_process_HOOK(&$variables)
 *   This is for modules that want to alter or provide extra variables for
 *   theming hooks not registered to itself. For example, if a module named
 *   "foo" wanted to alter the $classes_array variable for the hook "node" a
 *   process function of foo_process_node() can be created to intercept
 *   and alter the variable.
 *
 * - ENGINE_engine_process(&$variables)
 *   This function should only be implemented by theme engines and exists
 *   so that it can set necessary variables for all hooks.
 *
 * - ENGINE_engine_process_HOOK(&$variables)
 *   This is the same as the previous function, but it is called for a single
 *   theming hook.
 *
 * - ENGINE_process(&$variables)
 *   This is meant to be used by themes that utilize a theme engine. It is
 *   provided so that the processor is not locked into a specific theme.
 *   This makes it easy to share and transport code but theme authors must be
 *   careful to prevent fatal re-declaration errors when using sub-themes that
 *   have their own processor named exactly the same as its base theme. In
 *   the default theme engine (PHPTemplate), sub-themes will load their own
 *   template.php file in addition to the one used for its parent theme. This
 *   increases the risk for these errors. A good practice is to use the engine
 *   name for the base theme and the theme name for the sub-themes to minimize
 *   this possibility.
 *
 * - ENGINE_process_HOOK(&$variables)
 *   The same applies from the previous function, but it is called for a
 *   specific hook.
 *
 * - THEME_process(&$variables)
 *   These functions are based upon the raw theme; they should primarily be
 *   used by themes that do not use an engine or by sub-themes. It serves the
 *   same purpose as ENGINE_process().
 *
 * - THEME_process_HOOK(&$variables)
 *   The same applies from the previous function, but it is called for a
 *   specific hook.
 *
 * If the implementation is a function, only the hook-specific preprocess
 * and process functions (the ones ending in _HOOK) are called from the
 * above list. This is because theme hooks with function implementations
 * need to be fast, and calling the non-hook-specific preprocess and process
 * functions for them would incur a noticeable performance penalty.
 *
 * For template-implemented theme hooks, there are two special variables that
 * these preprocess and process functions can set:
 *   'template_file' and 'template_files'. These will be merged together
 *   to form a list of 'suggested' alternate template files to use, in
 *   reverse order of priority. template_file will always be a higher
 *   priority than items in template_files. theme() will then look for these
 *   files, one at a time, and use the first one that exists. If none exists,
 *   theme() will use the original registered file for the theme hook.
 *
 * For function-implemented theme hooks, there are two special variables that
 * these preprocess and process functions can set:
 *   'theme_function' and 'theme_functions'. These will be merged together
 *   to form a list of 'suggested' alternate functions to use, in
 *   reverse order of priority. theme_function will always be a higher
 *   priority than items in theme_functions. theme() will then call the
 *   highest priority function that exists. If none exists, theme() will call
 *   the original registered function for the theme hook.
 *
 * @param $hook
 *   The name of the theme function to call. May be an array, in which
 *   case the first hook that actually has an implementation registered
 *   will be used. This can be used to choose 'fallback' theme implementations,
 *   so that if the specific theme hook isn't implemented anywhere, a more
 *   generic one will be used. This can allow themes to create specific theme
 *   implementations for named objects.
 *
 * @param $variables
 *   An associative array of variables to merge with defaults from the theme
 *   registry, pass to preprocess and process functions for modification, and
 *   finally, pass to the function or template implementing the theme hook.
 *   Alternatively, this can be a renderable array, in which case, its properties
 *   are mapped to variables expected by the theme hook implementations.
 *
 * @return
 *   An HTML string that generates the themed output.
 */
function theme($hook, $variables = array()) {
  static $hooks = NULL;
  if (!isset($hooks)) {
    drupal_theme_initialize();
    $hooks = theme_get_registry();
  }

  // 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 (!isset($hooks[$hook])) {
    watchdog('theme', 'Theme key "@key" not found.', array('@key' => $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 function/template should be used.
  if (isset($info['preprocess functions']) || isset($info['process functions'])) {
    $variables['theme_functions'] = array();
    $variables['template_files'] = 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);
          }
        }
      }
    }
    // Function suggestion takes priority over template suggestion.
    // theme_function takes priority over theme_functions.
    // theme_functions are in FILO order (least appropriate to most appropriate).
    // Here, just look for function suggestions. Deal with template
    // suggestions only after determining that the theme call is a template.
    $suggestions = array();
    if (!empty($variables['theme_functions'])) {
      $suggestions = $variables['theme_functions'];
    }
    if (!empty($variables['theme_function'])) {
      $suggestions[] = $variables['theme_function'];
    }
    foreach (array_reverse($suggestions) as $suggestion) {
      if (function_exists($suggestion)) {
        $info['function'] = $suggestion;
        break;
      }
    }
  }

  // Generate the output using either a function or a template.
  if (isset($info['function'])) {
    if (function_exists($info['function'])) {
      $output = $info['function']($variables);
    }
  }
  else {
    // Default render function and extension.
    $render_function = 'theme_render_template';
    $extension = '.tpl.php';

    // Run through the theme engine variables, if necessary
    global $theme_engine;
    if (isset($theme_engine)) {
      // If theme or theme engine is implementing this, it may have
      // a different extension and a different renderer.
      if ($info['type'] != 'module') {
        if (function_exists($theme_engine . '_render_template')) {
          $render_function = $theme_engine . '_render_template';
        }
        $extension_function = $theme_engine . '_extension';
        if (function_exists($extension_function)) {
          $extension = $extension_function();
        }
      }
    }

    // Find which template file exists and can be used. Priority order is:
    // 1. $variables['template_file'].
    // 2. $variables['template_files'] in FILO order (later in array is higher
    //    priority).
    // 3. $info['template'].
    $suggestions = array();
    if (isset($variables['template_files'])) {
      $suggestions = $variables['template_files'];
    }
    if (isset($variables['template_file'])) {
      $suggestions[] = $variables['template_file'];
    }
    if ($suggestions) {
      $template_file = drupal_discover_template($info['theme paths'], $suggestions, $extension);
    }
    if (empty($template_file)) {
      $template_file = $info['template'] . $extension;
      if (isset($info['path'])) {
        $template_file = $info['path'] . '/' . $template_file;
      }
    }

    // Render the output using the found template file.
    $output = $render_function($template_file, $variables);
  }

  // restore path_to_theme()
  $theme_path = $temp;
  return $output;
}

/**
 * Determine and return which template file will generate the output.
 *
 * This helper allows the theme system to pick the template at runtime instead
 * of build time.
 *
 * @see template_page_suggestions()
 * @see template_preprocess_block()
 *
 * @param $paths
 *   The paths where templates can be found. See _theme_process_registry()
 *   'theme paths' for more information.
 * @param $suggestions
 *   The possible template names. These are derived from
 *   $variables['template_files'] and $variables['template_file], defined by
 *   preprocess functions. Each file is checked on every path in the order of
 *   precedence defined by theme().
 * @return
 *   The filepath to the template that will generate the output. If none is
 *   found, then theme() will use the 'template' as set by
 *   _theme_process_registry().
 *
 * @see _theme_process_registry()
 * @see theme()
 */
function drupal_discover_template($paths, $suggestions, $extension = '.tpl.php') {
  global $theme_engine;

  // Remove slashes or null to prevent files from being included from
  // an unexpected location (especially on Windows servers).
  $extension = str_replace(array("/", "\\", "\0"), '', $extension);

  // Loop through all paths and suggestions in FIFO order.
  $suggestions = array_reverse($suggestions);
  $paths = array_reverse($paths);
  foreach ($suggestions as $suggestion) {
    if (!empty($suggestion)) {
      $suggestion = str_replace(array("/", "\\", "\0"), '', $suggestion);
      foreach ($paths as $path) {
        if (file_exists($file = $path . '/' . $suggestion . $extension)) {
          return $file;
        }
      }
    }
  }
}

/**
 * Return the path to the current themed element.
 *
 * It can point to the active theme or the module handling a themed implementation.
 * For example, when invoked within the scope of a theming call it will depend
 * on where the theming function is handled. If implemented from a module, it
 * will point to the module. If implemented from the active theme, it will point
 * to the active theme. When called outside the scope of a theming call, it will
 * always point to the active theme.
 */
function path_to_theme() {
  global $theme_path;

  if (!isset($theme_path)) {
    drupal_theme_initialize();
  }

  return $theme_path;
}

/**
 * Allow themes and/or theme engines to easily discover overridden theme functions.
 *
 * @param $cache
 *   The existing cache of theme hooks to test against.
 * @param $prefixes
 *   An array of prefixes to test, in reverse order of importance.
 *
 * @return $templates
 *   The functions found, suitable for returning from hook_theme;
 */
function drupal_find_theme_functions($cache, $prefixes) {
  $templates = array();
  $functions = get_defined_functions();

  foreach ($cache as $hook => $info) {
    foreach ($prefixes as $prefix) {
      if (!empty($info['pattern'])) {
        $matches = preg_grep('/^' . $prefix . '_' . $info['pattern'] . '/', $functions['user']);
        if ($matches) {
          foreach ($matches as $match) {
            $new_hook = str_replace($prefix . '_', '', $match);
            $arg_name = isset($info['variables']) ? 'variables' : 'render element';
            $templates[$new_hook] = array(
              'function' => $match,
              $arg_name => $info[$arg_name],
            );
          }
        }
      }
      if (function_exists($prefix . '_' . $hook)) {
        $templates[$hook] = array(
          'function' => $prefix . '_' . $hook,
        );
        // Ensure that the pattern is maintained from base themes to its sub-themes.
        // Each sub-theme will have their functions scanned so the pattern must be
        // held for subsequent runs.
        if (isset($info['pattern'])) {
          $templates[$hook]['pattern'] = $info['pattern'];
        }
      }
    }
  }

  return $templates;
}

/**
 * Allow themes and/or theme engines to easily discover overridden templates.
 *
 * @param $cache
 *   The existing cache of theme hooks to test against.
 * @param $extension
 *   The extension that these templates will have.
 * @param $path
 *   The path to search.
 */
function drupal_find_theme_templates($cache, $extension, $path) {
  $templates = array();

  // Collect paths to all sub-themes grouped by base themes. These will be
  // used for filtering. This allows base themes to have sub-themes in its
  // folder hierarchy without affecting the base themes template discovery.
  $theme_paths = array();
  foreach (list_themes() as $theme_info) {
    if (!empty($theme_info->base_theme)) {
      $theme_paths[$theme_info->base_theme][$theme_info->name] = dirname($theme_info->filename);
    }
  }
  foreach ($theme_paths as $basetheme => $subthemes) {
    foreach ($subthemes as $subtheme => $subtheme_path) {
      if (isset($theme_paths[$subtheme])) {
        $theme_paths[$basetheme] = array_merge($theme_paths[$basetheme], $theme_paths[$subtheme]);
      }
    }
  }
  global $theme;
  $subtheme_paths = isset($theme_paths[$theme]) ? $theme_paths[$theme] : array();

  // Escape the periods in the extension.
  $regex = '/' . str_replace('.', '\.', $extension) . '$/';
  // Because drupal_system_listing works the way it does, we check for real
  // templates separately from checking for patterns.
  $files = drupal_system_listing($regex, $path, 'name', 0);
  foreach ($files as $template => $file) {
    // Ignore sub-theme templates for the current theme.
    if (strpos($file->uri, str_replace($subtheme_paths, '', $file->uri)) !== 0) {
      continue;
    }
    // Chop off the remaining extensions if there are any. $template already
    // has the rightmost extension removed, but there might still be more,
    // such as with .tpl.php, which still has .tpl in $template at this point.
    if (($pos = strpos($template, '.')) !== FALSE) {
      $template = substr($template, 0, $pos);
    }
    // Transform - in filenames to _ to match function naming scheme
    // for the purposes of searching.
    $hook = strtr($template, '-', '_');
    if (isset($cache[$hook])) {
      $templates[$hook] = array(
        'template' => $template,
        'path' => dirname($file->uri),
      );
    }
    // Ensure that the pattern is maintained from base themes to its sub-themes.
    // Each sub-theme will have their templates scanned so the pattern must be
    // held for subsequent runs.
    if (isset($cache[$hook]['pattern'])) {
      $templates[$hook]['pattern'] = $cache[$hook]['pattern'];
    }
  }

  $patterns = array_keys($files);

  foreach ($cache as $hook => $info) {
    if (!empty($info['pattern'])) {
      // Transform _ in pattern to - to match file naming scheme
      // for the purposes of searching.
      $pattern = strtr($info['pattern'], '_', '-');

      $matches = preg_grep('/^' . $pattern . '/', $patterns);
      if ($matches) {
        foreach ($matches as $match) {
          $file = substr($match, 0, strpos($match, '.'));
          // Put the underscores back in for the hook name and register this pattern.
          $arg_name = isset($info['variables']) ? 'variables' : 'render element';
          $templates[strtr($file, '-', '_')] = array(
            'template' => $file,
            'path' => dirname($files[$match]->uri),
            $arg_name => $info[$arg_name],
          );
        }
      }
    }
  }
  return $templates;
}

/**
 * Retrieve a setting for the current theme or for a given theme.
 *
 * The final setting is arrived at by merging the default settings, the custom
 * theme settings defined in the theme's .info file, the site-wide settings, and
 * the settings defined for the specific theme. If an empty string is given for
 * $key, only the site-wide theme defaults are retrieved.
 *
 * The default values for each setting is defined in this function. To add new
 * settings, add their default values here, and then add form elements to
 * system_theme_settings() in system.admin.inc.
 *
 * @param $setting_name
 *  The name of the setting to be retrieved.
 * @param $theme
 *  The name of a given theme; defaults to the current theme.
 * @return
 *   The value of the requested setting, NULL if the setting does not exist.
 */
function theme_get_setting($setting_name, $theme = NULL) {
  $cache = &drupal_static(__FUNCTION__, array());

  // If no key is given, use the current theme if we can determine it.
  if (is_null($theme)) {
    $theme = !empty($GLOBALS['theme_key']) ? $GLOBALS['theme_key'] : '';
  }

  if (empty($cache[$theme])) {
    // Set the default settings.
    $cache[$theme] = array(
      'default_logo'                     =>  1,
      'logo_path'                        =>  '',
      'default_favicon'                  =>  1,
      'favicon_path'                     =>  '',
      // Use the IANA-registered MIME type for ICO files as default.
      'favicon_mimetype'                 =>  'image/vnd.microsoft.icon',
      'main_menu'                        =>  1,
      'secondary_menu'                   =>  1,
      'toggle_logo'                      =>  1,
      'toggle_favicon'                   =>  1,
      'toggle_name'                      =>  1,
      'toggle_slogan'                    =>  1,
      'toggle_node_user_picture'         =>  1,
      'toggle_comment_user_picture'      =>  1,
      'toggle_comment_user_verification' =>  1,
      'toggle_main_menu'                 =>  1,
      'toggle_secondary_menu'            =>  1,
    );

    // Get the default values for the custom settings from the .info file.
    if ($theme) {
      $themes = list_themes();
      $theme_object = $themes[$theme];

      // Create a list which includes the current theme and all its base themes.
      if (isset($theme_object->base_themes)) {
        $theme_keys = array_keys($theme_object->base_themes);
        $theme_keys[] = $theme;
      }
      else {
        $theme_keys = array($theme);
      }
      foreach ($theme_keys as $theme_key) {
        if (!empty($themes[$theme_key]->info['settings'])) {
          $cache[$theme] = array_merge($cache[$theme], $themes[$theme_key]->info['settings']);
        }
      }
    }

    // Get the saved global settings from the database.
    $cache[$theme] = array_merge($cache[$theme], variable_get('theme_settings', array()));

    if ($theme) {
      // Get the saved theme settings from the database.
      $cache[$theme] = array_merge($cache[$theme], variable_get('theme_' . $theme . '_settings', array()));

      // Generate the path to the logo image.
      if ($cache[$theme]['toggle_logo']) {
        if ($cache[$theme]['default_logo']) {
          $cache[$theme]['logo'] = file_create_url(dirname($theme_object->filename) . '/logo.png');
        }
        elseif ($cache[$theme]['logo_path']) {
          $cache[$theme]['logo'] = file_create_url($cache[$theme]['logo_path']);
        }
      }

      // Generate the path to the favicon.
      if ($cache[$theme]['toggle_favicon']) {
        if ($cache[$theme]['default_favicon']) {
          if (file_exists($favicon = dirname($theme_object->filename) . '/favicon.ico')) {
            $cache[$theme]['favicon'] = file_create_url($favicon);
          }
          else {
            $cache[$theme]['favicon'] = file_create_url('misc/favicon.ico');
          }
        }
        elseif ($cache[$theme]['favicon_path']) {
          $cache[$theme]['favicon'] = file_create_url($cache[$theme]['favicon_path']);
        }
        else {
          $cache[$theme]['toggle_favicon'] = FALSE;
        }
      }
    }
  }

  return isset($cache[$theme][$setting_name]) ? $cache[$theme][$setting_name] : NULL;
}

/**
 * Render a system default template, which is essentially a PHP template.
 *
 * @param $template_file
 *   The filename of the template to render. Note that this will overwrite
 *   anything stored in $variables['template_file'] if using a variable processor hook.
 * @param $variables
 *   A keyed array of variables that will appear in the output.
 *
 * @return
 *   The output generated by the template.
 */
function theme_render_template($template_file, $variables) {
  extract($variables, EXTR_SKIP);               // Extract the variables to a local namespace
  ob_start();                                   // Start output buffering
  include DRUPAL_ROOT . '/' . $template_file;   // Include the template file
  $contents = ob_get_contents();                // Get the contents of the buffer
  ob_end_clean();                               // End buffering and discard
  return $contents;                             // Return the contents
}

/**
 * @defgroup themeable Default theme implementations
 * @{
 * Functions and templates that present output to the user, and can be
 * implemented by themes.
 *
 * Drupal's presentation layer is a pluggable system known as the theme
 * layer. Each theme can take control over most of Drupal's output, and
 * has complete control over the CSS.
 *
 * Inside Drupal, the theme layer is utilized by the use of the theme()
 * function, which is passed the name of a component (the theme hook)
 * and an array of variables. For example,
 * theme('table', array('header' => $header, 'rows' => $rows));
 * Additionally, the theme() function can take an array of theme
 * hooks, which can be used to provide 'fallback' implementations to
 * allow for more specific control of output. For example, the function:
 * theme(array('table__foo', 'table'), $variables) would look to see if
 * 'table__foo' is registered anywhere; if it is not, it would 'fall back'
 * to the generic 'table' implementation. This can be used to attach specific
 * theme functions to named objects, allowing the themer more control over
 * specific types of output.
 *
 * As of Drupal 6, every theme hook is required to be registered by the
 * module that owns it, so that Drupal can tell what to do with it and
 * to make it simple for themes to identify and override the behavior
 * for these calls.
 *
 * The theme hooks are registered via hook_theme(), which returns an
 * array of arrays with information about the hook. It describes the
 * arguments the function or template will need, and provides
 * defaults for the template in case they are not filled in. If the default
 * implementation is a function, by convention it is named theme_HOOK().
 *
 * Each module should provide a default implementation for theme_hooks that
 * it registers. This implementation may be either a function or a template;
 * if it is a function it must be specified via hook_theme(). By convention,
 * default implementations of theme hooks are named theme_HOOK. Default
 * template implementations are stored in the module directory.
 *
 * Drupal's default template renderer is a simple PHP parsing engine that
 * includes the template and stores the output. Drupal's theme engines
 * can provide alternate template engines, such as XTemplate, Smarty and
 * PHPTal. The most common template engine is PHPTemplate (included with
 * Drupal and implemented in phptemplate.engine, which uses Drupal's default
 * template renderer.
 *
 * In order to create theme-specific implementations of these hooks, themes can
 * implement their own version of theme hooks, either as functions or templates.
 * These implementations will be used instead of the default implementation. If
 * using a pure .theme without an engine, the .theme is required to implement
 * its own version of hook_theme() to tell Drupal what it is implementing;
 * themes utilizing an engine will have their well-named theming functions
 * automatically registered for them. While this can vary based upon the theme
 * engine, the standard set by phptemplate is that theme functions should be
 * named THEMENAME_HOOK. For example, for Drupal's default theme (Garland) to
 * implement the 'table' hook, the phptemplate.engine would find
 * garland_table().
 *
 * The theme system is described and defined in theme.inc.
 *
 * @see theme()
 * @see hook_theme()
 */

/**
 * Formats text for emphasized display in a placeholder inside a sentence.
 * Used automatically by t().
 *
 * @param $variables
 *   An associative array containing:
 *   - text: The text to format (plain-text).
 *
 * @return
 *   The formatted text (html).
 */
function theme_placeholder($variables) {
  return '<em>' . check_plain($variables['text']) . '</em>';
}

/**
 * Return a themed set of status and/or error messages. The messages are grouped
 * by type.
 *
 * An invisible heading identifies the messages for assistive technology.
 * Sighted users see a colored box. See http://www.w3.org/TR/WCAG-TECHS/H69.html
 * for info.
 *
 * @param $variables
 *   An associative array containing:
 *   - display: (optional) Set to 'status' or 'error' to display only messages
 *     of that type.
 *
 * @return
 *   A string containing the messages.
 */
function theme_status_messages($variables) {
  $display = $variables['display'];
  $output = '';

  $status_heading = array(
    'status' => t('Status message'),
    'error' => t('Error message'),
    'warning' => t('Warning message'),
  );
  foreach (drupal_get_messages($display) as $type => $messages) {
    $output .= "<div class=\"messages $type\">\n";
    if (!empty($status_heading[$type])) {
      $output .= '<h2 class="element-invisible">' . $status_heading[$type] . "</h2>\n";
    }
    if (count($messages) > 1) {
      $output .= " <ul>\n";
      foreach ($messages as $message) {
        $output .= '  <li>' . $message . "</li>\n";
      }
      $output .= " </ul>\n";
    }
    else {
      $output .= $messages[0];
    }
    $output .= "</div>\n";
  }
  return $output;
}

/**
 * Return a themed link.
 *
 * All Drupal code that outputs a link should call the l() function. That
 * function performs some initial preprocessing, and then, if necessary,
 * calls theme('link') for rendering the anchor tag.
 *
 * To optimize performance for sites that don't need custom theming of links,
 * the l() function includes an inline copy of this function, and uses that copy
 * if none of the enabled modules or the active theme implement any preprocess
 * or process functions or override this theme implementation.
 *
 * @param $variables
 *   An associative array containing the keys 'text', 'path', and 'options'.
 *   See the l() function for information about these variables.
 *
 * @return
 *   An HTML string containing a link to the given path.
 *
 * @see l()
 */
function theme_link($variables) {
  return '<a href="' . check_plain(url($variables['path'], $variables['options'])) . '"' . drupal_attributes($variables['options']['attributes']) . '>' . ($variables['options']['html'] ? $variables['text'] : check_plain($variables['text'])) . '</a>';
}

/**
 * Return a themed set of links.
 *
 * @param $variables
 *   An associative array containing:
 *   - links: A keyed array of links to be themed. The key for each link is used
 *     as its css class. Each link should be itself an array, with the following
 *     keys:
 *      - title: the link text
 *      - href: the link URL. If omitted, the 'title' is shown as a plain text
 *        item in the links list.
 *      - html: (optional) set this to TRUE if 'title' is HTML so it will be
 *        escaped.
 *     Array items are passed on to the l() function's $options parameter when
 *     creating the link.
 *   - attributes: A keyed array of attributes.
 *   - heading: An optional keyed array or a string for a heading to precede the
 *     links. When using an array the following keys can be used:
 *      - text: the heading text
 *      - level: the heading level (e.g. 'h2', 'h3')
 *      - class: (optional) an array of the CSS classes for the heading
 *     When using a string it will be used as the text of the heading and the
 *     level will default to 'h2'.
 *     Headings should be used on navigation menus and any list of links that
 *     consistently appears on multiple pages. To make the heading invisible
 *     use the 'element-invisible' CSS class. Do not use 'display:none', which
 *     removes it from screen-readers and assistive technology. Headings allow
 *     screen-reader and keyboard only users to navigate to or skip the links.
 *     See http://juicystudio.com/article/screen-readers-display-none.php
 *     and http://www.w3.org/TR/WCAG-TECHS/H42.html for more information.
 *
 * @return
 *   A string containing an unordered list of links.
 */
function theme_links($variables) {
  $links = $variables['links'];
  $attributes = $variables['attributes'];
  $heading = $variables['heading'];
  global $language_url;
  $output = '';

  if (count($links) > 0) {
    $output = '';

    // Treat the heading first if it is present to prepend it to the
    // list of links.
    if (!empty($heading)) {
      if (is_string($heading)) {
        // Prepare the array that will be used when the passed heading
        // is a string.
        $heading = array(
          'text' => $heading,
          // Set the default level of the heading.
          'level' => 'h2',
        );
      }
      $output .= '<' . $heading['level'];
      if (!empty($heading['class'])) {
        $output .= drupal_attributes(array('class' => $heading['class']));
      }
      $output .= '>' . check_plain($heading['text']) . '</' . $heading['level'] . '>';
    }

    $output .= '<ul' . drupal_attributes($attributes) . '>';

    $num_links = count($links);
    $i = 1;

    foreach ($links as $key => $link) {
      $class = array($key);

      // Add first, last and active classes to the list of links to help out themers.
      if ($i == 1) {
        $class[] = 'first';
      }
      if ($i == $num_links) {
        $class[] = 'last';
      }
      if (isset($link['href']) && ($link['href'] == $_GET['q'] || ($link['href'] == '<front>' && drupal_is_front_page()))
          && (empty($link['language']) || $link['language']->language == $language_url->language)) {
        $class[] = 'active';
      }
      $output .= '<li' . drupal_attributes(array('class' => $class)) . '>';

      if (isset($link['href'])) {
        // Pass in $link as $options, they share the same keys.
        $output .= l($link['title'], $link['href'], $link);
      }
      elseif (!empty($link['title'])) {
        // Some links are actually not links, but we wrap these in <span> for adding title and class attributes.
        if (empty($link['html'])) {
          $link['title'] = check_plain($link['title']);
        }
        $span_attributes = '';
        if (isset($link['attributes'])) {
          $span_attributes = drupal_attributes($link['attributes']);
        }
        $output .= '<span' . $span_attributes . '>' . $link['title'] . '</span>';
      }

      $i++;
      $output .= "</li>\n";
    }

    $output .= '</ul>';
  }

  return $output;
}

/**
 * Return a themed image.
 *
 * @param $variables
 *   An associative array containing:
 *   - path: Either the path of the image file (relative to base_path()) or a
 *     full URL.
 *   - alt: The alternative text for text-based browsers.
 *   - title: The title text is displayed when the image is hovered in some
 *     popular browsers.
 *   - attributes: Associative array of attributes to be placed in the img tag.
 *   - getsize: If set to TRUE, the image's dimension are fetched and added as
 *     width/height attributes.
 *
 * @return
 *   A string containing the image tag.
 */
function theme_image($variables) {
  $path = $variables['path'];
  $alt = $variables['alt'];
  $title = $variables['title'];
  $attributes = $variables['attributes'];
  $getsize = $variables['getsize'];

  if (!$getsize || (is_file($path) && (list($width, $height, $type, $image_attributes) = @getimagesize($path)))) {
    $attributes = drupal_attributes($attributes);
    $url = file_create_url($path);
    return '<img src="' . check_url($url) . '" alt="' . check_plain($alt) . '" title="' . check_plain($title) . '" ' . (isset($image_attributes) ? $image_attributes : '') . $attributes . ' />';
  }
}

/**
 * Return a themed breadcrumb trail.
 *
 * @param $variables
 *   An associative array containing:
 *   - breadcrumb: An array containing the breadcrumb links.
 *
 * @return
 *   A string containing the breadcrumb output.
 */
function theme_breadcrumb($variables) {
  $breadcrumb = $variables['breadcrumb'];

  if (!empty($breadcrumb)) {
    // Provide a navigational heading to give context for breadcrumb links to
    // screen-reader users. Make the heading invisible with .element-invisible.
    $output = '<h2 class="element-invisible">' . t('You are here') . '</h2>';

    $output .= '<div class="breadcrumb">' . implode(' » ', $breadcrumb) . '</div>';
    return $output;
  }
}

/**
 * Return a themed submenu, typically displayed under the tabs.
 *
 * @param $variables
 *   An associative array containing:
 *   - links: An array of links.
 */
function theme_submenu($variables) {
  $links = $variables['links'];

  return '<div class="submenu">' . implode(' | ', $links) . '</div>';
}

/**
 * Return a themed table.
 *
 * @param $variables
 *   An associative array containing:
 *   - header: An array containing the table headers. Each element of the array
 *     can be either a localized string or an associative array with the
 *     following keys:
 *     - "data": The localized title of the table column.
 *     - "field": The database field represented in the table column (required
 *       if user is to be able to sort on this column).
 *     - "sort": A default sort order for this column ("asc" or "desc").
 *     - Any HTML attributes, such as "colspan", to apply to the column header
 *       cell.
 *   - rows: An array of table rows. Every row is an array of cells, or an
 *     associative array with the following keys:
 *     - "data": an array of cells
 *     - Any HTML attributes, such as "class", to apply to the table row.
 *     Each cell can be either a string or an associative array with the
 *     following keys:
 *     - "data": The string to display in the table cell.
 *     - "header": Indicates this cell is a header.
 *     - Any HTML attributes, such as "colspan", to apply to the table cell.
 *     Here's an example for $rows:
 *     @verbatim
 *     $rows = array(
 *       // Simple row
 *       array(
 *         'Cell 1', 'Cell 2', 'Cell 3'
 *       ),
 *       // Row with attributes on the row and some of its cells.
 *       array(
 *         'data' => array('Cell 1', array('data' => 'Cell 2', 'colspan' => 2)), 'class' => array('funky')
 *       )
 *     );
 *     @endverbatim
 *   - attributes: An array of HTML attributes to apply to the table tag.
 *   - caption: A localized string to use for the <caption> tag.
 *   - colgroups: An array of column groups. Each element of the array can be
 *     either:
 *     - An array of columns, each of which is an associative array of HTML
 *       attributes applied to the COL element.
 *     - An array of attributes applied to the COLGROUP element, which must
 *       include a "data" attribute. To add attributes to COL elements, set the
 *       "data" attribute with an array of columns, each of which is an
 *       associative array of HTML attributes.
 *     Here's an example for $colgroup:
 *     @verbatim
 *     $colgroup = array(
 *       // COLGROUP with one COL element.
 *       array(
 *         array(
 *           'class' => array('funky'), // Attribute for the COL element.
 *         ),
 *       ),
 *       // Colgroup with attributes and inner COL elements.
 *       array(
 *         'data' => array(
 *           array(
 *             'class' => array('funky'), // Attribute for the COL element.
 *           ),
 *         ),
 *         'class' => array('jazzy'), // Attribute for the COLGROUP element.
 *       ),
 *     );
 *     @endverbatim
 *     These optional tags are used to group and set properties on columns
 *     within a table. For example, one may easily group three columns and
 *     apply same background style to all.
 *   - sticky: Use a "sticky" table header.
 *
 * @return
 *   An HTML string representing the table.
 */
function theme_table($variables) {
  $header = $variables['header'];
  $rows = $variables['rows'];
  $attributes = $variables['attributes'];
  $caption = $variables['caption'];
  $colgroups = $variables['colgroups'];
  $sticky = $variables['sticky'];

  // Add sticky headers, if applicable.
  if (count($header) && $sticky) {
    drupal_add_js('misc/tableheader.js');
    // Add 'sticky-enabled' class to the table to identify it for JS.
    // This is needed to target tables constructed by this function.
    $attributes['class'][] = 'sticky-enabled';
  }

  $output = '<table' . drupal_attributes($attributes) . ">\n";

  if (isset($caption)) {
    $output .= '<caption>' . $caption . "</caption>\n";
  }

  // Format the table columns:
  if (count($colgroups)) {
    foreach ($colgroups as $number => $colgroup) {
      $attributes = array();

      // Check if we're dealing with a simple or complex column
      if (isset($colgroup['data'])) {
        foreach ($colgroup as $key => $value) {
          if ($key == 'data') {
            $cols = $value;
          }
          else {
            $attributes[$key] = $value;
          }
        }
      }
      else {
        $cols = $colgroup;
      }

      // Build colgroup
      if (is_array($cols) && count($cols)) {
        $output .= ' <colgroup' . drupal_attributes($attributes) . '>';
        $i = 0;
        foreach ($cols as $col) {
          $output .= ' <col' . drupal_attributes($col) . ' />';
        }
        $output .= " </colgroup>\n";
      }
      else {
        $output .= ' <colgroup' . drupal_attributes($attributes) . " />\n";
      }
    }
  }

  // Format the table header:
  if (count($header)) {
    $ts = tablesort_init($header);
    // HTML requires that the thead tag has tr tags in it followed by tbody
    // tags. Using ternary operator to check and see if we have any rows.
    $output .= (count($rows) ? ' <thead><tr>' : ' <tr>');
    foreach ($header as $cell) {
      $cell = tablesort_header($cell, $header, $ts);
      $output .= _theme_table_cell($cell, TRUE);
    }
    // Using ternary operator to close the tags based on whether or not there are rows
    $output .= (count($rows) ? " </tr></thead>\n" : "</tr>\n");
  }
  else {
    $ts = array();
  }

  // Format the table rows:
  if (count($rows)) {
    $output .= "<tbody>\n";
    $flip = array('even' => 'odd', 'odd' => 'even');
    $class = 'even';
    foreach ($rows as $number => $row) {
      $attributes = array();

      // Check if we're dealing with a simple or complex row
      if (isset($row['data'])) {
        foreach ($row as $key => $value) {
          if ($key == 'data') {
            $cells = $value;
          }
          else {
            $attributes[$key] = $value;
          }
        }
      }
      else {
        $cells = $row;
      }
      if (count($cells)) {
        // Add odd/even class
        $class = $flip[$class];
        $attributes['class'][] = $class;

        // Build row
        $output .= ' <tr' . drupal_attributes($attributes) . '>';
        $i = 0;
        foreach ($cells as $cell) {
          $cell = tablesort_cell($cell, $header, $ts, $i++);
          $output .= _theme_table_cell($cell);
        }
        $output .= " </tr>\n";
      }
    }
    $output .= "</tbody>\n";
  }

  $output .= "</table>\n";
  return $output;
}

/**
 * Returns a header cell for tables that have a select all functionality.
 */
function theme_table_select_header_cell() {
  drupal_add_js('misc/tableselect.js');

  return array('class' => array('select-all'));
}

/**
 * Return a themed sort icon.
 *
 * @param $variables
 *   An associative array containing:
 *   - style: Set to either asc or desc. This sets which icon to show.
 *
 * @return
 *   A themed sort icon.
 */
function theme_tablesort_indicator($variables) {
  if ($variables['style'] == "asc") {
    return theme('image', array('path' => 'misc/arrow-asc.png', 'alt' => t('sort ascending'), 'title' => t('sort ascending')));
  }
  else {
    return theme('image', array('path' => 'misc/arrow-desc.png', 'alt' => t('sort descending'), 'title' => t('sort descending')));
  }
}

/**
 * Return a themed marker, useful for marking new or updated
 * content.
 *
 * @param $variables
 *   An associative array containing:
 *   - type: Number representing the marker type to display.
 *     @see MARK_NEW, MARK_UPDATED, MARK_READ
 *
 * @return
 *   A string containing the marker.
 */
function theme_mark($variables) {
  $type = $variables['type'];
  global $user;
  if ($user->uid) {
    if ($type == MARK_NEW) {
      return ' <span class="marker">' . t('new') . '</span>';
    }
    elseif ($type == MARK_UPDATED) {
      return ' <span class="marker">' . t('updated') . '</span>';
    }
  }
}

/**
 * Return a themed list of items.
 *
 * @param $variables
 *   An associative array containing:
 *   - items: An array of items to be displayed in the list. If an item is a
 *     string, then it is used as is. If an item is an array, then the "data"
 *     element of the array is used as the contents of the list item. If an item
 *     is an array with a "children" element, those children are displayed in a
 *     nested list. All other elements are treated as attributes of the list
 *     item element.
 *   - title: The title of the list.
 *   - type: The type of list to return (e.g. "ul", "ol").
 *   - attributes: The attributes applied to the list element.
 *
 * @return
 *   A string containing the list output.
 */
function theme_item_list($variables) {
  $items = $variables['items'];
  $title = $variables['title'];
  $type = $variables['type'];
  $attributes = $variables['attributes'];

  $output = '<div class="item-list">';
  if (isset($title)) {
    $output .= '<h3>' . $title . '</h3>';
  }

  if (!empty($items)) {
    $output .= "<$type" . drupal_attributes($attributes) . '>';
    $num_items = count($items);
    foreach ($items as $i => $item) {
      $attributes = array();
      $children = array();
      if (is_array($item)) {
        foreach ($item as $key => $value) {
          if ($key == 'data') {
            $data = $value;
          }
          elseif ($key == 'children') {
            $children = $value;
          }
          else {
            $attributes[$key] = $value;
          }
        }
      }
      else {
        $data = $item;
      }
      if (count($children) > 0) {
        $data .= theme_item_list($children, NULL, $type, $attributes); // Render nested list
      }
      if ($i == 0) {
        $attributes['class'][] = 'first';
      }
      if ($i == $num_items - 1) {
        $attributes['class'][] = 'last';
      }
      $output .= '<li' . drupal_attributes($attributes) . '>' . $data . "</li>\n";
    }
    $output .= "</$type>";
  }
  $output .= '</div>';
  return $output;
}

/**
 * Returns code that emits the 'more help'-link.
 */
function theme_more_help_link($variables) {
  return '<div class="more-help-link">' . t('<a href="@link">More help</a>', array('@link' => check_url($variables['url']))) . '</div>';
}

/**
 * Return code that emits an feed icon.
 *
 * @param $variables
 *   An associative array containing:
 *   - url: The url of the feed.
 *   - title: A descriptive title of the feed.
 */
function theme_feed_icon($variables) {
  $text = t('Subscribe to @feed-title', array('@feed-title' => $variables['title']));
  if ($image = theme('image', array('path' => 'misc/feed.png', 'alt' => $text))) {
    return '<a href="' . check_url($variables['url']) . '" title="' . $text . '" class="feed-icon">' . $image . '</a>';
  }
}

/**
 * Generate the output for a generic HTML tag with attributes.
 *
 * This theme function should be used for tags appearing in the HTML HEAD of a
 * document (specified via the #tag property in the passed $element):
 *
 * @param $variables
 *   An associative array containing:
 *   - element: An associative array describing the tag:
 *     - #tag: The tag name to output.  Typical tags added to the HTML HEAD:
 *       - meta: To provide meta information, such as a page refresh.
 *       - link: To refer to stylesheets and other contextual information.
 *       - script: To load JavaScript.
 *     - #attributes: (optional) An array of HTML attributes to apply to the
 *       tag.
 *     - #value: (optional) A string containing tag content, such as inline CSS.
 *     - #value_prefix: (optional) A string to prepend to #value, e.g. a CDATA
 *       wrapper prefix.
 *     - #value_suffix: (optional) A string to append to #value, e.g. a CDATA
 *       wrapper suffix.
 *
 * @ingroup themeable
 */
function theme_html_tag($variables) {
  $element = $variables['element'];
  if (!isset($element['#value'])) {
    return '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . " />\n";
  }
  else {
    $output = '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . '>';
    if (isset($element['#value_prefix'])) {
      $output .= $element['#value_prefix'];
    }
    $output .= $element['#value'];
    if (isset($element['#value_suffix'])) {
      $output .= $element['#value_suffix'];
    }
    $output .= '</' . $element['#tag'] . ">\n";
    return $output;
  }
}

/**
 * Returns code that emits the 'more' link used on blocks.
 *
 * @param $variables
 *   An associative array containing:
 *   - url: The url of the main page
 *   - title: A descriptive verb for the link, like 'Read more'
 */
function theme_more_link($variables) {
  return '<div class="more-link">' . t('<a href="@link" title="@title">more</a>', array('@link' => check_url($variables['url']), '@title' => $variables['title'])) . '</div>';
}

/**
 * Preprocess variables for theme_username().
 *
 * Modules that make any changes to variables like 'name' or 'extra' must insure
 * that the final string is safe to include directly in the ouput by using
 * check_plain() or filter_xss().
 *
 * @see theme_username().
 */
function template_preprocess_username(&$variables) {
  $account = $variables['account'];

  $variables['extra'] = '';
  if (empty($account->uid)) {
   $variables['uid'] = 0;
   if (theme_get_setting('toggle_comment_user_verification')) {
     $variables['extra'] = ' (' . t('not verified') . ')';
   }
  }
  else {
    $variables['uid'] = (int)$account->uid;
  }

  // Set the name to a formatted name that is safe for printing and
  // that won't break tables by being too long. Keep an unshortened,
  // unsanitized version, in case other preproces functions want to implement
  // their own shortening logic or add markup. If they do so, they must ensure
  // that $variables['name'] is safe for printing.
  $name = $variables['name_raw'] = format_username($account);
  if (drupal_strlen($name) > 20) {
    $name = drupal_substr($name, 0, 15) . '...';
  }
  $variables['name'] = check_plain($name);

  $variables['profile_access'] = user_access('access user profiles');
  $variables['link_attributes'] = array();
  // Populate link path and attributes if appropriate.
  if ($variables['uid'] && $variables['profile_access']) {
    // We are linking to a local user.
    $variables['link_attributes'] = array('title' => t('View user profile.'));
    $variables['link_path'] = 'user/' . $variables['uid'];
  }
  elseif (!empty($account->homepage)) {
    // Like the 'class' attribute, the 'rel' attribute can hold a
    // space-separated set of values, so initialize it as an array to make it
    // easier for other preprocess functions to append to it.
    $variables['link_attributes'] = array('rel' => array('nofollow'));
    $variables['link_path'] = $account->homepage;
    $variables['homepage'] = $account->homepage;
  }
  // We do not want the l() function to check_plain() a second time.
  $variables['link_options']['html'] = TRUE;
  // Set a default class.
  $variables['attributes_array'] = array('class' => array('username'));
}

/**
 * Process variables for theme_username().
 *
 * @see theme_username().
 */
function template_process_username(&$variables) {
  // Finalize the link_options array for passing to the l() function.
  // This is done in the process phase so that attributes may be added by
  // modules or the theme during the preprocess phase.
  if (isset($variables['link_path'])) {
    // $variables['attributes_array'] contains attributes that should be applied
    // regardless of whether a link is being rendered or not.
    // $variables['link_attributes'] contains attributes that should only be
    // applied if a link is being rendered. Preprocess functions are encouraged
    // to use the former unless they want to add attributes on the link only.
    // If a link is being rendered, these need to be merged. Some attributes are
    // themselves arrays, so the merging needs to be recursive.
    $variables['link_options']['attributes'] = array_merge_recursive($variables['link_attributes'], $variables['attributes_array']);
  }
}

/**
 * Format a username.
 *
 * @param $variables
 *   An associative array containing:
 *   - account: The user object to format.
 *   - name: The user's name, sanitized.
 *   - extra: Additional text to append to the user's name, sanitized.
 *   - link_path: The path or URL of the user's profile page, home page, or
 *     other desired page to link to for more information about the user.
 *   - link_options: An array of options to pass to the l() function's $options
 *     parameter if linking the user's name to the user's page.
 *   - attributes_array: An array of attributes to pass to the
 *     drupal_attributes() function if not linking to the user's page.
 *
 * @return
 *   A themed HTML string containing the user's name, potentially linked to the
 *   user's page.
 *
 * @see template_preprocess_username()
 * @see template_process_username()
 */
function theme_username($variables) {
  if (isset($variables['link_path'])) {
    // We have a link path, so we should generate a link using l().
    // Additional classes may be added as array elements like
    // $variables['link_options']['attributes']['class'][] = 'myclass';
    $output = l($variables['name'] . $variables['extra'], $variables['link_path'], $variables['link_options']);
  }
  else {
    // Modules may have added important attributes so they must be included
    // in the output. Additional classes may be added as array elements like
    // $variables['attributes_array']['class'][] = 'myclass';
    $output = '<span' . drupal_attributes($variables['attributes_array']) . '>' . $variables['name'] . $variables['extra'] . '</span>';
  }
  return $output;
}

/**
 * Return a themed progress bar.
 *
 * @param $variables
 *   An associative array containing:
 *   - percent: The percentage of the progress.
 *   - message: A string containing information to be displayed.
 *
 * @return
 *   A themed HTML string representing the progress bar.
 */
function theme_progress_bar($variables) {
  $output = '<div id="progress" class="progress">';
  $output .= '<div class="bar"><div class="filled" style="width: ' . $variables['percent'] . '%"></div></div>';
  $output .= '<div class="percentage">' . $variables['percent'] . '%</div>';
  $output .= '<div class="message">' . $variables['message'] . '</div>';
  $output .= '</div>';

  return $output;
}

/**
 * Create a standard indentation div. Used for drag and drop tables.
 *
 * @param $variables
 *   An associative array containing:
 *   - size: Optional. The number of indentations to create.
 *
 * @return
 *   A string containing indentations.
 */
function theme_indentation($variables) {
  $output = '';
  for ($n = 0; $n < $variables['size']; $n++) {
    $output .= '<div class="indentation">&nbsp;</div>';
  }
  return $output;
}

/**
 * @} End of "defgroup themeable".
 */

function _theme_table_cell($cell, $header = FALSE) {
  $attributes = '';

  if (is_array($cell)) {
    $data = isset($cell['data']) ? $cell['data'] : '';
    // Cell's data property can be a string or a renderable array.
    if (is_array($data)) {
      $data = drupal_render($data);
    }
    $header |= isset($cell['header']);
    unset($cell['data']);
    unset($cell['header']);
    $attributes = drupal_attributes($cell);
  }
  else {
    $data = $cell;
  }

  if ($header) {
    $output = "<th$attributes>$data</th>";
  }
  else {
    $output = "<td$attributes>$data</td>";
  }

  return $output;
}

/**
 * Adds a default set of helper variables for variable processors and templates.
 * This comes in before any other preprocess function which makes it possible to
 * be used in default theme implementations (non-overriden theme functions).
 */
function template_preprocess(&$variables, $hook) {
  global $user;
  static $count = array();

  // Track run count for each hook to provide zebra striping.
  // See "template_preprocess_block()" which provides the same feature specific to blocks.
  $count[$hook] = isset($count[$hook]) && is_int($count[$hook]) ? $count[$hook] : 1;
  $variables['zebra'] = ($count[$hook] % 2) ? 'odd' : 'even';
  $variables['id'] = $count[$hook]++;

  // Tell all templates where they are located.
  $variables['directory'] = path_to_theme();

  // Initialize html class attribute for the current hook.
  $variables['classes_array'] = array($hook);

  // Initialize attributes for the top-level template entity and its title and
  // content.
  $variables['attributes_array'] = array();
  $variables['title_attributes_array'] = array();
  $variables['content_attributes_array'] = array();

  // Set default variables that depend on the database.
  $variables['is_admin']            = FALSE;
  $variables['is_front']            = FALSE;
  $variables['logged_in']           = FALSE;
  if ($variables['db_is_active'] = db_is_active()  && !defined('MAINTENANCE_MODE')) {
    // Check for administrators.
    if (user_access('access administration pages')) {
      $variables['is_admin'] = TRUE;
    }
    // Flag front page status.
    $variables['is_front'] = drupal_is_front_page();
    // Tell all templates by which kind of user they're viewed.
    $variables['logged_in'] = ($user->uid > 0);
    // Provide user object to all templates
    $variables['user'] = $user;
  }
}

/**
 * A default process function used to alter variables as late as possible.
 */
function template_process(&$variables, $hook) {
  // Flatten out classes.
  $variables['classes'] = implode(' ', $variables['classes_array']);

  // Flatten out attributes, title_attributes, and content_attributes.
  $variables['attributes'] = drupal_attributes($variables['attributes_array']);
  $variables['title_attributes'] = drupal_attributes($variables['title_attributes_array']);
  $variables['content_attributes'] = drupal_attributes($variables['content_attributes_array']);
}

/**
 * Preprocess variables for html.tpl.php
 *
 * @see system_elements()
 * @see html.tpl.php
 */
function template_preprocess_html(&$variables) {
  // Compile a list of classes that are going to be applied to the body element.
  // This allows advanced theming based on context (home page, node of certain type, etc.).
  // Add a class that tells us whether we're on the front page or not.
  $variables['classes_array'][] = $variables['is_front'] ? 'front' : 'not-front';
  // Add a class that tells us whether the page is viewed by an authenticated user or not.
  $variables['classes_array'][] = $variables['logged_in'] ? 'logged-in' : 'not-logged-in';

  // Add information about the number of sidebars.
  if (!empty($variables['page']['sidebar_first']) && !empty($variables['page']['sidebar_second'])) {
    $variables['classes_array'][] = 'two-sidebars';
  }
  elseif (!empty($variables['page']['sidebar_first'])) {
    $variables['classes_array'][] = 'one-sidebar sidebar-first';
  }
  elseif (!empty($variables['page']['sidebar_second'])) {
    $variables['classes_array'][] = 'one-sidebar sidebar-second';
  }
  else {
    $variables['classes_array'][] = 'no-sidebars';
  }

  // Populate the body classes.
  if ($suggestions = template_page_suggestions(arg(), 'page')) {
    foreach ($suggestions as $suggestion) {
      if ($suggestion != 'page-front') {
        // Add current suggestion to page classes to make it possible to theme
        // the page depending on the current page type (e.g. node, admin, user,
        // etc.) as well as more specific data like node-12 or node-edit.
        $variables['classes_array'][] = drupal_html_class($suggestion);
      }
    }
  }

  // If on an individual node page, add the node type to body classes.
  if ($node = menu_get_object()) {
    $variables['classes_array'][] = drupal_html_class('node-type-' . $node->type);
  }

  // RDFa allows annotation of XHTML pages with RDF data, while GRDDL provides
  // mechanisms for extraction of this RDF content via XSLT transformation
  // using an associated GRDDL profile.
  $variables['rdf_namespaces']    = drupal_get_rdf_namespaces();
  $variables['grddl_profile']     = 'http://ns.inria.fr/grddl/rdfa/';
  $variables['language']          = $GLOBALS['language'];
  $variables['language']->dir     = $GLOBALS['language']->direction ? 'rtl' : 'ltr';

  // Add favicon.
  if (theme_get_setting('toggle_favicon')) {
    $favicon = theme_get_setting('favicon');
    $type = theme_get_setting('favicon_mimetype');
    drupal_add_html_head_link(array('rel' => 'shortcut icon', 'href' => check_url($favicon), 'type' => $type));
  }

  // Construct page title.
  if (drupal_get_title()) {
    $head_title = array(strip_tags(drupal_get_title()), variable_get('site_name', 'Drupal'));
  }
  else {
    $head_title = array(variable_get('site_name', 'Drupal'));
    if (variable_get('site_slogan', '')) {
      $head_title[] = variable_get('site_slogan', '');
    }
  }
  $variables['head_title'] = implode(' | ', $head_title);

  // Populate the page template suggestions.
  if ($suggestions = template_page_suggestions(arg(), 'html')) {
    $variables['template_files'] = $suggestions;
  }
}

/**
 * Preprocess variables for page.tpl.php
 *
 * Most themes utilize their own copy of page.tpl.php. The default is located
 * inside "modules/system/page.tpl.php". Look in there for the full list of
 * variables.
 *
 * Uses the arg() function to generate a series of page template suggestions
 * based on the current path.
 *
 * Any changes to variables in this preprocessor should also be changed inside
 * template_preprocess_maintenance_page() to keep all of them consistent.
 *
 * @see drupal_render_page
 * @see template_process_page
 * @see page.tpl.php
 */
function template_preprocess_page(&$variables) {
  // Move some variables to the top level for themer convenience and template cleanliness.
  $variables['show_messages'] = $variables['page']['#show_messages'];

  foreach (system_region_list($GLOBALS['theme']) as $region_key => $region_name) {
    if (!isset($variables['page'][$region_key])) {
      $variables['page'][$region_key] = array();
    }
  }

  // Set up layout variable.
  $variables['layout'] = 'none';
  if (!empty($variables['page']['sidebar_first'])) {
    $variables['layout'] = 'first';
  }
  if (!empty($variables['page']['sidebar_second'])) {
    $variables['layout'] = ($variables['layout'] == 'first') ? 'both' : 'second';
  }

  $variables['base_path']         = base_path();
  $variables['front_page']        = url();
  $variables['breadcrumb']        = theme('breadcrumb', array('breadcrumb' => drupal_get_breadcrumb()));
  $variables['feed_icons']        = drupal_get_feeds();
  $variables['language']          = $GLOBALS['language'];
  $variables['language']->dir     = $GLOBALS['language']->direction ? 'rtl' : 'ltr';
  $variables['logo']              = theme_get_setting('logo');
  $variables['messages']          = $variables['show_messages'] ? theme('status_messages') : '';
  $variables['main_menu']         = theme_get_setting('toggle_main_menu') ? menu_main_menu() : array();
  $variables['secondary_menu']    = theme_get_setting('toggle_secondary_menu') ? menu_secondary_menu() : array();
  $variables['action_links']      = menu_local_actions();
  $variables['site_name']         = (theme_get_setting('toggle_name') ? filter_xss_admin(variable_get('site_name', 'Drupal')) : '');
  $variables['site_slogan']       = (theme_get_setting('toggle_slogan') ? filter_xss_admin(variable_get('site_slogan', '')) : '');
  $variables['tabs']              = theme('menu_local_tasks');
  $variables['title']             = drupal_get_title();

  if ($node = menu_get_object()) {
    $variables['node'] = $node;
  }

  // Populate the page template suggestions.
  if ($suggestions = template_page_suggestions(arg(), 'page')) {
    $variables['template_files'] = $suggestions;
  }
}
/**
 * Process variables for html.tpl.php
 *
 * Perform final addition and modification of variables before passing into
 * the template. To customize these variables, call drupal_render() on elements
 * in $variables['page'] during THEME_preprocess_page().
 *
 * @see template_preprocess_html()
 * @see html.tpl.php
 */
function template_process_html(&$variables) {
  // Render page_top and page_bottom into top level variables.
  $variables['page_top'] = drupal_render($variables['page']['page_top']);
  $variables['page_bottom'] = drupal_render($variables['page']['page_bottom']);
  // Place the rendered HTML for the page body into a top level variable.
  $variables['page']              = $variables['page']['#children'];
  $variables['page_bottom'] .= drupal_get_js('footer');

  $variables['head']    = drupal_get_html_head();
  $variables['css']     = drupal_add_css();
  $variables['styles']  = drupal_get_css();
  $variables['scripts'] = drupal_get_js();
}

/**
 * Generate an array of page template suggestions.
 *
 * @param $args
 *   An array of path arguments, such as from function arg().
 *
 * @return
 *   An array of suggested template files.
 */
function template_page_suggestions($args, $suggestion) {

  // Build a list of suggested template files and body classes in order of
  // specificity. One suggestion is made for every element of the current path,
  // though numeric elements are not carried to subsequent suggestions. For
  // example, http://www.example.com/node/1/edit would result in the following
  // suggestions and body classes:
  //
  // page-node-edit.tpl.php  page-node-edit
  // page-node-1.tpl.php     page-node-1
  // page-node.tpl.php       page-node
  // page.tpl.php

  $suggestions = array();
  foreach ($args as $arg) {
    // Remove slashes or null per SA-CORE-2009-003.
    $arg = str_replace(array("/", "\\", "\0"), '', $arg);
    // The percent acts as a wildcard for numeric arguments since
    // asterisks are not valid filename characters on many filesystems.
    if (is_numeric($arg)) {
      $suggestions[] = $suggestion . '-%';
    }
    $suggestions[] = $suggestion . '-' . $arg;
    if (!is_numeric($arg)) {
      $suggestion .= '-' . $arg;
    }
  }
  if (drupal_is_front_page()) {
    $suggestions[] = $suggestion . '-front';
  }

  return $suggestions;
}

/**
 * The variables generated here is a mirror of template_preprocess_page().
 * This preprocessor will run it's course when theme_maintenance_page() is
 * invoked. It is also used in theme_install_page() and theme_update_page() to
 * keep all the variables consistent.
 *
 * An alternate template file of "maintenance-page-offline.tpl.php" can be
 * used when the database is offline to hide errors and completely replace the
 * content.
 *
 * The $variables array contains the following arguments:
 * - $content
 *
 * @see maintenance-page.tpl.php
 */
function template_preprocess_maintenance_page(&$variables) {
  // Add favicon
  if (theme_get_setting('toggle_favicon')) {
    $favicon = theme_get_setting('favicon');
    $type = theme_get_setting('favicon_mimetype');
    drupal_add_html_head_link(array('rel' => 'shortcut icon', 'href' => check_url($favicon), 'type' => $type));
  }

  global $theme;
  // Retrieve the theme data to list all available regions.
  $theme_data = _system_rebuild_theme_data();
  $regions = $theme_data[$theme]->info['regions'];

  // Get all region content set with drupal_add_region_content().
  foreach (array_keys($regions) as $region) {
    // Assign region to a region variable.
    $region_content = drupal_get_region_content($region);
    isset($variables[$region]) ? $variables[$region] .= $region_content : $variables[$region] = $region_content;
  }

  // Setup layout variable.
  $variables['layout'] = 'none';
  if (!empty($variables['sidebar_first'])) {
    $variables['layout'] = 'first';
  }
  if (!empty($variables['sidebar_second'])) {
    $variables['layout'] = ($variables['layout'] == 'first') ? 'both' : 'second';
  }

  // Construct page title
  if (drupal_get_title()) {
    $head_title = array(strip_tags(drupal_get_title()), variable_get('site_name', 'Drupal'));
  }
  else {
    $head_title = array(variable_get('site_name', 'Drupal'));
    if (variable_get('site_slogan', '')) {
      $head_title[] = variable_get('site_slogan', '');
    }
  }
  $variables['head_title']        = implode(' | ', $head_title);
  $variables['base_path']         = base_path();
  $variables['front_page']        = url();
  $variables['breadcrumb']        = '';
  $variables['feed_icons']        = '';
  $variables['head']              = drupal_get_html_head();
  $variables['help']              = '';
  $variables['language']          = $GLOBALS['language'];
  $variables['language']->dir     = $GLOBALS['language']->direction ? 'rtl' : 'ltr';
  $variables['logo']              = theme_get_setting('logo');
  $variables['messages']          = $variables['show_messages'] ? theme('status_messages') : '';
  $variables['main_menu']         = array();
  $variables['secondary_menu']    = array();
  $variables['site_name']         = (theme_get_setting('toggle_name') ? variable_get('site_name', 'Drupal') : '');
  $variables['site_slogan']       = (theme_get_setting('toggle_slogan') ? variable_get('site_slogan', '') : '');
  $variables['css']               = drupal_add_css();
  $variables['styles']            = drupal_get_css();
  $variables['scripts']           = drupal_get_js();
  $variables['tabs']              = '';
  $variables['title']             = drupal_get_title();
  $variables['closure']           = '';

  // Compile a list of classes that are going to be applied to the body element.
  $variables['classes_array'][] = 'in-maintenance';
  if (isset($variables['db_is_active']) && !$variables['db_is_active']) {
    $variables['classes_array'][] = 'db-offline';
  }
  if ($variables['layout'] == 'both') {
    $variables['classes_array'][] = 'two-sidebars';
  }
  elseif ($variables['layout'] == 'none') {
    $variables['classes_array'][] = 'no-sidebars';
  }
  else {
    $variables['classes_array'][] = 'one-sidebar sidebar-' . $variables['layout'];
  }

  // Dead databases will show error messages so supplying this template will
  // allow themers to override the page and the content completely.
  if (isset($variables['db_is_active']) && !$variables['db_is_active']) {
    $variables['template_file'] = 'maintenance-page-offline';
  }
}

/**
 * Preprocess variables for region.tpl.php
 *
 * Prepare the values passed to the theme_region function to be passed into a
 * pluggable template engine. Uses the region name to generate a template file
 * suggestions. If none are found, the default region.tpl.php is used.
 *
 * @see region.tpl.php
 */
function template_preprocess_region(&$variables) {
  // Create the $content variable that templates expect.
  $variables['content'] = $variables['elements']['#children'];
  $variables['region'] = $variables['elements']['#region'];

  $region = 'region-' . str_replace('_', '-', $variables['region']);
  $variables['classes_array'][] = $region;
  $variables['template_files'][] = $region;
}