Skip navigation
Help

theme

6 theme.inc theme()
7 theme.inc theme($hook, $variables = array())

Generates themed output.

All requests for themed output must go through this function. It examines the request and routes it to the appropriate theme function or template, by checking the theme registry.

The first argument to this function is the name of the theme hook. For instance, to theme a table, the theme hook name is 'table'. By default, this theme hook could be implemented by a function called 'theme_table' or a template file called 'table.tpl.php', but hook_theme() can override the default function or template name.

If the implementation is a template file, several functions are called before the template file is invoked, to modify the $variables array. These fall into the "preprocessing" phase and the "processing" phase, and are executed (if they exist), in the following order (note that in the following list, HOOK indicates the theme hook name, MODULE indicates a module name, THEME indicates a theme name, and ENGINE indicates a theme engine name):

  • template_preprocess(&$variables, $hook): Creates a default set of variables for all theme hooks.
  • template_preprocess_HOOK(&$variables): Should be implemented by the module that registers the theme hook, to set up default variables.
  • MODULE_preprocess(&$variables, $hook): hook_preprocess() is invoked on all implementing modules.
  • MODULE_preprocess_HOOK(&$variables): hook_preprocess_HOOK() is invoked on all implementing modules, so that modules that didn't define the theme hook can alter the variables.
  • ENGINE_engine_preprocess(&$variables, $hook): Allows the theme engine to set necessary variables for all theme hooks.
  • ENGINE_engine_preprocess_HOOK(&$variables): Allows the theme engine to set necessary variables for the particular theme hook.
  • THEME_preprocess(&$variables, $hook): Allows the theme to set necessary variables for all theme hooks.
  • THEME_preprocess_HOOK(&$variables): Allows the theme to set necessary variables specific to the particular theme hook.
  • template_process(&$variables, $hook): Creates a default set of variables for all theme hooks.
  • template_process_HOOK(&$variables): This is the first processor specific to the theme hook; it should be implemented by the module that registers it.
  • MODULE_process(&$variables, $hook): hook_process() is invoked on all implementing modules.
  • MODULE_process_HOOK(&$variables): hook_process_HOOK() is invoked on on all implementing modules, so that modules that didn't define the theme hook can alter the variables.
  • ENGINE_engine_process(&$variables, $hook): Allows the theme engine to set necessary variables for all theme hooks.
  • ENGINE_engine_process_HOOK(&$variables): Allows the theme engine to set necessary variables for the particular theme hook.
  • ENGINE_process(&$variables, $hook): Allows the theme engine to process the variables.
  • ENGINE_process_HOOK(&$variables): Allows the theme engine to process the variables specific to the theme hook.
  • THEME_process(&$variables, $hook): Allows the theme to process the variables.
  • THEME_process_HOOK(&$variables): Allows the theme to process the variables specific to the theme hook.

If the implementation is a function, only the theme-hook-specific preprocess and process functions (the ones ending in _HOOK) are called from the list above. This is because theme hooks with function implementations need to be fast, and calling the non-theme-hook-specific preprocess and process functions for them would incur a noticeable performance penalty.

There are two special variables that these preprocess and process functions can set: 'theme_hook_suggestion' and 'theme_hook_suggestions'. These will be merged together to form a list of 'suggested' alternate theme hooks to use, in reverse order of priority. theme_hook_suggestion will always be a higher priority than items in theme_hook_suggestions. theme() will use the highest priority implementation that exists. If none exists, theme() will use the implementation for the theme hook it was called with. These suggestions are similar to and are used for similar reasons as calling theme() with an array as the $hook parameter (see below). The difference is whether the suggestions are determined by the code that calls theme() or by a preprocess or process function.

Parameters

$hook: The name of the theme hook to call. If the name contains a double-underscore ('__') and there isn't an implementation for the full name, the part before the '__' is checked. This allows a fallback to a more generic implementation. For example, if theme('links__node', ...) is called, but there is no implementation of that theme hook, then the 'links' implementation is used. This process is iterative, so if theme('links__contextual__node', ...) is called, theme() checks for the following implementations, and uses the first one that exists:

  • links__contextual__node
  • links__contextual
  • links

This allows themes to create specific theme implementations for named objects and contexts of otherwise generic theme hooks. The $hook parameter may also be an array, in which case the first theme hook that has an implementation is used. This allows for the code that calls theme() to explicitly specify the fallback order in a situation where using the '__' convention is not desired or is insufficient.

$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 value

An HTML string representing the themed output.

317 calls to theme()

76 string references to 'theme'

File

drupal/includes/theme.inc, line 751
The theme system, which controls the output of Drupal.

Code

function theme($hook, $variables = array()) {
  static $hooks = NULL;

  // If called before all modules are loaded, we do not necessarily have a full
  // theme registry to work with, and therefore cannot process the theme
  // request properly. See also _theme_load_registry().
  if (!module_load_all(NULL) && !defined('MAINTENANCE_MODE')) {
    throw new Exception(t('theme() may not be called until all modules are loaded.'));
  }

  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 there's no implementation, check for more generic fallbacks. If there's
  // still no implementation, log an error and return an empty string.
  if (!isset($hooks[$hook])) {
    // Iteratively strip everything after the last '__' delimiter, until an
    // implementation is found.
    while ($pos = strrpos($hook, '__')) {
      $hook = substr($hook, 0, $pos);
      if (isset($hooks[$hook])) {
        break;
      }
    }
    if (!isset($hooks[$hook])) {
      // Only log a message when not trying theme suggestions ($hook being an
      // array).
      if (!isset($candidate)) {
        watchdog('theme', 'Theme 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 hook's template/function to use. If the
  // hook is a suggestion of a base hook, invoke the variable processors of
  // the base hook, but retain the suggestion as a high priority suggestion to
  // be used unless overridden by a variable processor function.
  if (isset($info['base hook'])) {
    $base_hook = $info['base hook'];
    $base_hook_info = $hooks[$base_hook];
    if (isset($base_hook_info['preprocess functions']) || isset($base_hook_info['process functions'])) {
      $variables['theme_hook_suggestion'] = $hook;
      $hook = $base_hook;
      $info = $base_hook_info;
    }
  }
  if (isset($info['preprocess functions']) || isset($info['process functions'])) {
    $variables['theme_hook_suggestions'] = array();
    foreach (array('preprocess functions', 'process functions') as $phase) {
      if (!empty($info[$phase])) {
        foreach ($info[$phase] as $processor_function) {
          if (function_exists($processor_function)) {
            // We don't want a poorly behaved process function changing $hook.
            $hook_clone = $hook;
            $processor_function($variables, $hook_clone);
          }
        }
      }
    }
    // If the preprocess/process functions specified hook suggestions, and the
    // suggestion exists in the theme registry, use it instead of the hook that
    // theme() was called with. This allows the preprocess/process step to
    // route to a more specific theme hook. For example, a function may call
    // theme('node', ...), but a preprocess function can add 'node__article' as
    // a suggestion, enabling a theme to have an alternate template file for
    // article nodes. Suggestions are checked in the following order:
    // - The 'theme_hook_suggestion' variable is checked first. It overrides
//   all others.
    // - The 'theme_hook_suggestions' variable is checked in FILO order, so the
//   last suggestion added to the array takes precedence over suggestions
//   added earlier.
    $suggestions = array();
    if (!empty($variables['theme_hook_suggestions'])) {
      $suggestions = $variables['theme_hook_suggestions'];
    }
    if (!empty($variables['theme_hook_suggestion'])) {
      $suggestions[] = $variables['theme_hook_suggestion'];
    }
    foreach (array_reverse($suggestions) as $suggestion) {
      if (isset($hooks[$suggestion])) {
        $info = $hooks[$suggestion];
        break;
      }
    }
  }

  // Generate the output using either a function or a template.
  $output = '';
  if (isset($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';

    // The theme engine may use a different extension and a different renderer.
    global $theme_engine;
    if (isset($theme_engine)) {
      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();
        }
      }
    }

    // In some cases, a template implementation may not have had
    // template_preprocess() run (for example, if the default implementation is
    // a function, but a template overrides that default implementation). In
    // these cases, a template should still be able to expect to have access to
    // the variables provided by template_preprocess(), so we add them here if
    // they don't already exist. We don't want to run template_preprocess()
    // twice (it would be inefficient and mess up zebra striping), so we use the
    // 'directory' variable to determine if it has already run, which while not
    // completely intuitive, is reasonably safe, and allows us to save on the
    // overhead of adding some new variable to track that.
    if (!isset($variables['directory'])) {
      $default_template_variables = array();
      template_preprocess($default_template_variables, $hook);
      $variables += $default_template_variables;
    }

    // Render the output using the template file.
    $template_file = $info['template'] . $extension;
    if (isset($info['path'])) {
      $template_file = $info['path'] . '/' . $template_file;
    }
    $output = $render_function($template_file, $variables);
  }

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