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<?php
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/**
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 * @defgroup forms Form builder functions
 * @{
 * Functions that build an abstract representation of a HTML form.
 *
 * All modules should declare their form builder functions to be in this
 * group and each builder function should reference its validate and submit
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 * functions using \@see. Conversely, validate and submit functions should
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 * reference the form builder function using \@see. For examples, of this see
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 * system_modules_uninstall() or user_pass(), the latter of which has the
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 * following in its doxygen documentation:
 *
 * \@ingroup forms
 * \@see user_pass_validate().
 * \@see user_pass_submit().
 *
 * @} End of "defgroup forms".
 */

/**
 * @defgroup form_api Form generation
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 * @{
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 * Functions to enable the processing and display of HTML forms.
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 *
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 * Drupal uses these functions to achieve consistency in its form processing and
 * presentation, while simplifying code and reducing the amount of HTML that
 * must be explicitly generated by modules.
 *
 * The drupal_get_form() function handles retrieving, processing, and
 * displaying a rendered HTML form for modules automatically. For example:
 *
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 * @code
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 * // Display the user registration form.
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 * $output = drupal_get_form('user_register');
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 * @endcode
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 *
 * Forms can also be built and submitted programmatically without any user input
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 * using the drupal_execute() function.
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 *
 * For information on the format of the structured arrays used to define forms,
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 * and more detailed explanations of the Form API workflow, see the
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 * @link http://api.drupal.org/api/file/developer/topics/forms_api_reference.html/6 reference @endlink
 * and the @link http://drupal.org/node/204270 Form API guide. @endlink
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 */

/**
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 * Retrieves a form from a constructor function, or from the cache if
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 * the form was built in a previous page-load. The form is then passed
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 * on for processing, after and rendered for display if necessary.
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 *
 * @param $form_id
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 *   The unique string identifying the desired form. If a function
 *   with that name exists, it is called to build the form array.
 *   Modules that need to generate the same form (or very similar forms)
 *   using different $form_ids can implement hook_forms(), which maps
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 *   different $form_id values to the proper form constructor function. Examples
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 *   may be found in node_forms(), search_forms(), and user_forms().
 * @param ...
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 *   Any additional arguments are passed on to the functions called by
 *   drupal_get_form(), including the unique form constructor function.
 *   For example, the node_edit form requires that a node object be passed
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 *   in here when it is called. These are available to implementations of
 *   hook_form_alter() and hook_form_FORM_ID_alter() as the array
 *   $form['#parameters'].
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 * @return
 *   The rendered form.
 */
function drupal_get_form($form_id) {
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  $form_state = array('storage' => NULL, 'submitted' => FALSE);

  $args = func_get_args();
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  $cacheable = FALSE;
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  if (isset($_SESSION['batch_form_state'])) {
    // We've been redirected here after a batch processing : the form has
    // already been processed, so we grab the post-process $form_state value
    // and move on to form display. See _batch_finished() function.
    $form_state = $_SESSION['batch_form_state'];
    unset($_SESSION['batch_form_state']);
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  }
  else {
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    // If the incoming $_POST contains a form_build_id, we'll check the
    // cache for a copy of the form in question. If it's there, we don't
    // have to rebuild the form to proceed. In addition, if there is stored
    // form_state data from a previous step, we'll retrieve it so it can
    // be passed on to the form processing code.
    if (isset($_POST['form_id']) && $_POST['form_id'] == $form_id && !empty($_POST['form_build_id'])) {
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      $form = form_get_cache($_POST['form_build_id'], $form_state);
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    }

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    // If the previous bit of code didn't result in a populated $form
    // object, we're hitting the form for the first time and we need
    // to build it from scratch.
    if (!isset($form)) {
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      $form_state['post'] = $_POST;
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      // Use a copy of the function's arguments for manipulation
      $args_temp = $args;
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      $args_temp[0] = &$form_state;
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      array_unshift($args_temp, $form_id);
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      $form = call_user_func_array('drupal_retrieve_form', $args_temp);
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      $form_build_id = 'form-'. md5(uniqid(mt_rand(), TRUE));
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      $form['#build_id'] = $form_build_id;
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      drupal_prepare_form($form_id, $form, $form_state);
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      // Store a copy of the unprocessed form for caching and indicate that it
      // is cacheable if #cache will be set.
      $original_form = $form;
      $cacheable = TRUE;
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      unset($form_state['post']);
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    }
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    $form['#post'] = $_POST;
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    // Now that we know we have a form, we'll process it (validating,
    // submitting, and handling the results returned by its submission
    // handlers. Submit handlers accumulate data in the form_state by
    // altering the $form_state variable, which is passed into them by
    // reference.
    drupal_process_form($form_id, $form, $form_state);
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    if ($cacheable && !empty($form['#cache'])) {
      // Caching is done past drupal_process_form so #process callbacks can
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      // set #cache.
      form_set_cache($form_build_id, $original_form, $form_state);
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    }
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  }

  // Most simple, single-step forms will be finished by this point --
  // drupal_process_form() usually redirects to another page (or to
  // a 'fresh' copy of the form) once processing is complete. If one
  // of the form's handlers has set $form_state['redirect'] to FALSE,
  // the form will simply be re-rendered with the values still in its
  // fields.
  //
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  // If $form_state['storage'] or $form_state['rebuild'] has been set
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  // and input has been processed, we know that we're in a complex
  // multi-part process of some sort and the form's workflow is NOT
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  // complete. We need to construct a fresh copy of the form, passing
  // in the latest $form_state in addition to any other variables passed
  // into drupal_get_form().
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  if ((!empty($form_state['storage']) || !empty($form_state['rebuild'])) && !empty($form_state['process_input']) && !form_get_errors()) {
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    $form = drupal_rebuild_form($form_id, $form_state, $args);
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  }

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  // If we haven't redirected to a new location by now, we want to
  // render whatever form array is currently in hand.
  return drupal_render_form($form_id, $form);
}
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/**
 * Retrieves a form, caches it and processes it with an empty $_POST.
 *
 * This function clears $_POST and passes the empty $_POST to the form_builder.
 * To preserve some parts from $_POST, pass them in $form_state.
 *
 * If your AHAH callback simulates the pressing of a button, then your AHAH
 * callback will need to do the same as what drupal_get_form would do when the
 * button is pressed: get the form from the cache, run drupal_process_form over
 * it and then if it needs rebuild, run drupal_rebuild_form over it. Then send
 * back a part of the returned form.
 * $form_state['clicked_button']['#array_parents'] will help you to find which
 * part.
 *
 * @param $form_id
 *   The unique string identifying the desired form. If a function
 *   with that name exists, it is called to build the form array.
 *   Modules that need to generate the same form (or very similar forms)
 *   using different $form_ids can implement hook_forms(), which maps
 *   different $form_id values to the proper form constructor function. Examples
 *   may be found in node_forms(), search_forms(), and user_forms().
 * @param $form_state
 *   A keyed array containing the current state of the form. Most
 *   important is the $form_state['storage'] collection.
 * @param $args
 *   Any additional arguments are passed on to the functions called by
 *   drupal_get_form(), plus the original form_state in the beginning. If you
 *   are getting a form from the cache, use $form['#parameters'] to shift off
 *   the $form_id from its beginning then the resulting array can be used as
 *   $arg here.
 * @param $form_build_id
 *   If the AHAH callback calling this function only alters part of the form,
 *   then pass in the existing form_build_id so we can re-cache with the same
 *   csid.
 * @return
 *   The newly built form.
 */
function drupal_rebuild_form($form_id, &$form_state, $args, $form_build_id = NULL) {
  // Remove the first argument. This is $form_id.when called from
  // drupal_get_form and the original $form_state when called from some AHAH
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  // callback. Neither is needed. After that, put in the current state.
  $args[0] = &$form_state;
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  // And the form_id.
  array_unshift($args, $form_id);
  $form = call_user_func_array('drupal_retrieve_form', $args);

  if (!isset($form_build_id)) {
    // We need a new build_id for the new version of the form.
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    $form_build_id = 'form-'. md5(uniqid(mt_rand(), TRUE));
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  }
  $form['#build_id'] = $form_build_id;
  drupal_prepare_form($form_id, $form, $form_state);

  // Now, we cache the form structure so it can be retrieved later for
  // validation. If $form_state['storage'] is populated, we'll also cache
  // it so that it can be used to resume complex multi-step processes.
  form_set_cache($form_build_id, $form, $form_state);

  // Clear out all post data, as we don't want the previous step's
  // data to pollute this one and trigger validate/submit handling,
  // then process the form for rendering.
  $_POST = array();
  $form['#post'] = array();
  drupal_process_form($form_id, $form, $form_state);
  return $form;
}

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/**
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 * Store a form in the cache.
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 */
function form_set_cache($form_build_id, $form, $form_state) {
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  global $user;
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  // 6 hours cache life time for forms should be plenty.
  $expire = 21600;
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  if ($user->uid) {
    $form['#cache_token'] = drupal_get_token();
  }
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  cache_set('form_'. $form_build_id, $form, 'cache_form', time() + $expire);
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  if (!empty($form_state['storage'])) {
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    cache_set('storage_'. $form_build_id, $form_state['storage'], 'cache_form', time() + $expire);
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  }
}

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/**
 * Fetch a form from cache.
 */
function form_get_cache($form_build_id, &$form_state) {
  global $user;
  if ($cached = cache_get('form_'. $form_build_id, 'cache_form')) {
    $form = $cached->data;
    if ((isset($form['#cache_token']) && drupal_valid_token($form['#cache_token'])) || (!isset($form['#cache_token']) && !$user->uid)) {
      if ($cached = cache_get('storage_'. $form_build_id, 'cache_form')) {
        $form_state['storage'] = $cached->data;
      }
      return $form;
    }
  }
}

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/**
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 * Retrieves, populates, and processes a form.
 *
 * This function allows you to supply values for form elements and submit a
 * form for processing. Compare to drupal_get_form(), which also builds and
 * processes a form, but does not allow you to supply values.
 *
 * There is no return value, but you can check to see if there are errors by
 * calling form_get_errors().
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 *
 * @param $form_id
 *   The unique string identifying the desired form. If a function
 *   with that name exists, it is called to build the form array.
 *   Modules that need to generate the same form (or very similar forms)
 *   using different $form_ids can implement hook_forms(), which maps
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 *   different $form_id values to the proper form constructor function. Examples
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 *   may be found in node_forms(), search_forms(), and user_forms().
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 * @param $form_state
 *   A keyed array containing the current state of the form. Most
 *   important is the $form_state['values'] collection, a tree of data
 *   used to simulate the incoming $_POST information from a user's
 *   form submission.
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 * @param ...
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 *   Any additional arguments are passed on to the functions called by
 *   drupal_execute(), including the unique form constructor function.
 *   For example, the node_edit form requires that a node object be passed
 *   in here when it is called.
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 * For example:
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 * @code
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 * // register a new user
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 * $form_state = array();
 * $form_state['values']['name'] = 'robo-user';
 * $form_state['values']['mail'] = 'robouser@example.com';
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 * $form_state['values']['pass']['pass1'] = 'password';
 * $form_state['values']['pass']['pass2'] = 'password';
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 * $form_state['values']['op'] = t('Create new account');
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 * drupal_execute('user_register', $form_state);
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 *
 * // Create a new node
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 * $form_state = array();
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 * module_load_include('inc', 'node', 'node.pages');
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 * $node = array('type' => 'story');
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 * $form_state['values']['title'] = 'My node';
 * $form_state['values']['body'] = 'This is the body text!';
 * $form_state['values']['name'] = 'robo-user';
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 * $form_state['values']['op'] = t('Save');
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 * drupal_execute('story_node_form', $form_state, (object)$node);
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 * @endcode
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 */
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function drupal_execute($form_id, &$form_state) {
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  $args = func_get_args();
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  // Make sure $form_state is passed around by reference.
  $args[1] = &$form_state;
  
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  $form = call_user_func_array('drupal_retrieve_form', $args);
  $form['#post'] = $form_state['values'];
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  // Reset form validation.
  $form_state['must_validate'] = TRUE;
  form_set_error(NULL, '', TRUE);

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  drupal_prepare_form($form_id, $form, $form_state);
  drupal_process_form($form_id, $form, $form_state);
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}

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/**
 * Retrieves the structured array that defines a given form.
 *
 * @param $form_id
 *   The unique string identifying the desired form. If a function
 *   with that name exists, it is called to build the form array.
 *   Modules that need to generate the same form (or very similar forms)
 *   using different $form_ids can implement hook_forms(), which maps
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 *   different $form_id values to the proper form constructor function.
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 * @param $form_state
 *   A keyed array containing the current state of the form.
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 * @param ...
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 *   Any additional arguments needed by the unique form constructor
 *   function. Generally, these are any arguments passed into the
 *   drupal_get_form() or drupal_execute() functions after the first
 *   argument. If a module implements hook_forms(), it can examine
 *   these additional arguments and conditionally return different
 *   builder functions as well.
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 */
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function drupal_retrieve_form($form_id, &$form_state) {
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  static $forms;

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  // We save two copies of the incoming arguments: one for modules to use
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  // when mapping form ids to constructor functions, and another to pass to
  // the constructor function itself. We shift out the first argument -- the
  // $form_id itself -- from the list to pass into the constructor function,
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  // since it's already known.
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  $args = func_get_args();
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  $saved_args = $args;
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  array_shift($args);
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  if (isset($form_state)) {
    array_shift($args);
  }
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  // We first check to see if there's a function named after the $form_id.
  // If there is, we simply pass the arguments on to it to get the form.
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  if (!function_exists($form_id)) {
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    // In cases where many form_ids need to share a central constructor function,
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    // such as the node editing form, modules can implement hook_forms(). It
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    // maps one or more form_ids to the correct constructor functions.
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    //
    // We cache the results of that hook to save time, but that only works
    // for modules that know all their form_ids in advance. (A module that
    // adds a small 'rate this comment' form to each comment in a list
    // would need a unique form_id for each one, for example.)
    //
    // So, we call the hook if $forms isn't yet populated, OR if it doesn't
    // yet have an entry for the requested form_id.
    if (!isset($forms) || !isset($forms[$form_id])) {
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      $forms = module_invoke_all('forms', $form_id, $args);
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    }
    $form_definition = $forms[$form_id];
    if (isset($form_definition['callback arguments'])) {
      $args = array_merge($form_definition['callback arguments'], $args);
    }
    if (isset($form_definition['callback'])) {
      $callback = $form_definition['callback'];
    }
  }
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  array_unshift($args, NULL);
  $args[0] = &$form_state;
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  // If $callback was returned by a hook_forms() implementation, call it.
  // Otherwise, call the function named after the form id.
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  $form = call_user_func_array(isset($callback) ? $callback : $form_id, $args);

  // We store the original function arguments, rather than the final $arg
  // value, so that form_alter functions can see what was originally
  // passed to drupal_retrieve_form(). This allows the contents of #parameters
  // to be saved and passed in at a later date to recreate the form.
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  $form['#parameters'] = $saved_args;
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  return $form;
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}

/**
 * This function is the heart of form API. The form gets built, validated and in
 * appropriate cases, submitted.
 *
 * @param $form_id
 *   The unique string identifying the current form.
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 * @param $form
 *   An associative array containing the structure of the form.
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 * @param $form_state
 *   A keyed array containing the current state of the form. This
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 *   includes the current persistent storage data for the form, and
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 *   any data passed along by earlier steps when displaying a
 *   multi-step form. Additional information, like the sanitized $_POST
 *   data, is also accumulated here.
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 */
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function drupal_process_form($form_id, &$form, &$form_state) {
  $form_state['values'] = array();

  $form = form_builder($form_id, $form, $form_state);
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  // Only process the form if it is programmed or the form_id coming
  // from the POST data is set and matches the current form_id.
  if ((!empty($form['#programmed'])) || (!empty($form['#post']) && (isset($form['#post']['form_id']) && ($form['#post']['form_id'] == $form_id)))) {
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    $form_state['process_input'] = TRUE;
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    drupal_validate_form($form_id, $form, $form_state);

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    // form_clean_id() maintains a cache of element IDs it has seen,
    // so it can prevent duplicates. We want to be sure we reset that
    // cache when a form is processed, so scenerios that result in
    // the form being built behind the scenes and again for the
    // browser don't increment all the element IDs needlessly.
    form_clean_id(NULL, TRUE);

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    if ((!empty($form_state['submitted'])) && !form_get_errors() && empty($form_state['rebuild'])) {
      $form_state['redirect'] = NULL;
      form_execute_handlers('submit', $form, $form_state);

      // We'll clear out the cached copies of the form and its stored data
      // here, as we've finished with them. The in-memory copies are still
      // here, though.
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      if (variable_get('cache', CACHE_DISABLED) == CACHE_DISABLED && !empty($form_state['values']['form_build_id'])) {
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        cache_clear_all('form_'. $form_state['values']['form_build_id'], 'cache_form');
        cache_clear_all('storage_'. $form_state['values']['form_build_id'], 'cache_form');
      }

      // If batches were set in the submit handlers, we process them now,
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      // possibly ending execution. We make sure we do not react to the batch
      // that is already being processed (if a batch operation performs a
      // drupal_execute).
      if ($batch =& batch_get() && !isset($batch['current_set'])) {
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        // The batch uses its own copies of $form and $form_state for
        // late execution of submit handers and post-batch redirection.
        $batch['form'] = $form;
        $batch['form_state'] = $form_state;
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        $batch['progressive'] = !$form['#programmed'];
        batch_process();
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        // Execution continues only for programmatic forms.
        // For 'regular' forms, we get redirected to the batch processing
        // page. Form redirection will be handled in _batch_finished(),
        // after the batch is processed.
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      }
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      // If no submit handlers have populated the $form_state['storage']
      // bundle, and the $form_state['rebuild'] flag has not been set,
      // we're finished and should redirect to a new destination page
      // if one has been set (and a fresh, unpopulated copy of the form
      // if one hasn't). If the form was called by drupal_execute(),
      // however, we'll skip this and let the calling function examine
      // the resulting $form_state bundle itself.
      if (!$form['#programmed'] && empty($form_state['rebuild']) && empty($form_state['storage'])) {
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        drupal_redirect_form($form, $form_state['redirect']);
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      }
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    }
  }
}

/**
 * Prepares a structured form array by adding required elements,
 * executing any hook_form_alter functions, and optionally inserting
 * a validation token to prevent tampering.
 *
 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 * @param $form
 *   An associative array containing the structure of the form.
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 * @param $form_state
 *   A keyed array containing the current state of the form. Passed
 *   in here so that hook_form_alter() calls can use it, as well.
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 */
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function drupal_prepare_form($form_id, &$form, &$form_state) {
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  global $user;

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  $form['#type'] = 'form';
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  $form['#programmed'] = isset($form['#post']);
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  if (isset($form['#build_id'])) {
    $form['form_build_id'] = array(
      '#type' => 'hidden',
      '#value' => $form['#build_id'],
      '#id' => $form['#build_id'],
      '#name' => 'form_build_id',
    );
  }

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  // Add a token, based on either #token or form_id, to any form displayed to
  // authenticated users. This ensures that any submitted form was actually
  // requested previously by the user and protects against cross site request
  // forgeries.
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  if (isset($form['#token'])) {
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    if ($form['#token'] === FALSE || $user->uid == 0 || $form['#programmed']) {
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      unset($form['#token']);
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    }
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    else {
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      $form['form_token'] = array('#type' => 'token', '#default_value' => drupal_get_token($form['#token']));
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    }
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  }
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  else if (isset($user->uid) && $user->uid && !$form['#programmed']) {
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    $form['#token'] = $form_id;
    $form['form_token'] = array(
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      '#id' => form_clean_id('edit-'. $form_id .'-form-token'),
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      '#type' => 'token',
      '#default_value' => drupal_get_token($form['#token']),
    );
  }

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  if (isset($form_id)) {
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    $form['form_id'] = array(
      '#type' => 'hidden',
      '#value' => $form_id,
      '#id' => form_clean_id("edit-$form_id"),
    );
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  }
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  if (!isset($form['#id'])) {
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    $form['#id'] = form_clean_id($form_id);
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  }
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  $form += _element_info('form');
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  if (!isset($form['#validate'])) {
    if (function_exists($form_id .'_validate')) {
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      $form['#validate'] = array($form_id .'_validate');
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    }
  }

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  if (!isset($form['#submit'])) {
    if (function_exists($form_id .'_submit')) {
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      // We set submit here so that it can be altered.
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      $form['#submit'] = array($form_id .'_submit');
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    }
  }

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  // Normally, we would call drupal_alter($form_id, $form, $form_state).
  // However, drupal_alter() normally supports just one byref parameter. Using
  // the __drupal_alter_by_ref key, we can store any additional parameters
  // that need to be altered, and they'll be split out into additional params
  // for the hook_form_alter() implementations.
  // @todo: Remove this in Drupal 7.
  $data = &$form;
  $data['__drupal_alter_by_ref'] = array(&$form_state);
  drupal_alter('form_'. $form_id, $data);

  // __drupal_alter_by_ref is unset in the drupal_alter() function, we need
  // to repopulate it to ensure both calls get the data.
  $data['__drupal_alter_by_ref'] = array(&$form_state);
  drupal_alter('form', $data, $form_id);
557 558
}

559 560

/**
561
 * Validates user-submitted form data from the $form_state using
562 563 564 565 566 567 568
 * the validate functions defined in a structured form array.
 *
 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 * @param $form
 *   An associative array containing the structure of the form.
569 570 571 572 573 574 575 576 577 578
 * @param $form_state
 *   A keyed array containing the current state of the form. The current
 *   user-submitted data is stored in $form_state['values'], though
 *   form validation functions are passed an explicit copy of the
 *   values for the sake of simplicity. Validation handlers can also
 *   $form_state to pass information on to submit handlers. For example:
 *     $form_state['data_for_submision'] = $data;
 *   This technique is useful when validation requires file parsing,
 *   web service requests, or other expensive requests that should
 *   not be repeated in the submission step.
579
 */
580
function drupal_validate_form($form_id, $form, &$form_state) {
581 582
  static $validated_forms = array();

583
  if (isset($validated_forms[$form_id]) && empty($form_state['must_validate'])) {
584 585
    return;
  }
586

587
  // If the session token was set by drupal_prepare_form(), ensure that it
588
  // matches the current user's session.
589
  if (isset($form['#token'])) {
590
    if (!drupal_valid_token($form_state['values']['form_token'], $form['#token'])) {
591
      // Setting this error will cause the form to fail validation.
592
      form_set_error('form_token', t('Validation error, please try again. If this error persists, please contact the site administrator.'));
593 594 595
    }
  }

596
  _form_validate($form, $form_state, $form_id);
597
  $validated_forms[$form_id] = TRUE;
598 599
}

600 601 602 603 604 605 606 607 608
/**
 * Renders a structured form array into themed HTML.
 *
 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 * @param $form
 *   An associative array containing the structure of the form.
 * @return
609
 *   A string containing the themed HTML.
610
 */
611
function drupal_render_form($form_id, &$form) {
612 613
  // Don't override #theme if someone already set it.
  if (!isset($form['#theme'])) {
614 615 616
    init_theme();
    $registry = theme_get_registry();
    if (isset($registry[$form_id])) {
617 618 619 620
      $form['#theme'] = $form_id;
    }
  }

621
  $output = drupal_render($form);
622 623 624 625 626 627 628 629 630
  return $output;
}

/**
 * Redirect the user to a URL after a form has been processed.
 *
 * @param $form
 *   An associative array containing the structure of the form.
 * @param $redirect
631
 *   An optional value containing the destination path to redirect
632 633 634
 *   to if none is specified by the form.
 */
function drupal_redirect_form($form, $redirect = NULL) {
635
  $goto = NULL;
636 637 638
  if (isset($redirect)) {
    $goto = $redirect;
  }
639
  if ($goto !== FALSE && isset($form['#redirect'])) {
640 641
    $goto = $form['#redirect'];
  }
642 643 644 645 646 647 648 649 650 651 652
  if (!isset($goto) || ($goto !== FALSE)) {
    if (isset($goto)) {
      if (is_array($goto)) {
        call_user_func_array('drupal_goto', $goto);
      }
      else {
        drupal_goto($goto);
      }
    }
    drupal_goto($_GET['q']);
  }
653 654
}

655 656 657 658 659 660 661
/**
 * Performs validation on form elements. First ensures required fields are
 * completed, #maxlength is not exceeded, and selected options were in the
 * list of options given to the user. Then calls user-defined validators.
 *
 * @param $elements
 *   An associative array containing the structure of the form.
662 663 664 665 666 667 668 669 670 671
 * @param $form_state
 *   A keyed array containing the current state of the form. The current
 *   user-submitted data is stored in $form_state['values'], though
 *   form validation functions are passed an explicit copy of the
 *   values for the sake of simplicity. Validation handlers can also
 *   $form_state to pass information on to submit handlers. For example:
 *     $form_state['data_for_submision'] = $data;
 *   This technique is useful when validation requires file parsing,
 *   web service requests, or other expensive requests that should
 *   not be repeated in the submission step.
672 673 674 675
 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 */
676
function _form_validate($elements, &$form_state, $form_id = NULL) {
677 678
  static $complete_form;

679 680
  // Also used in the installer, pre-database setup.
  $t = get_t();
681

682 683 684
  // Recurse through all children.
  foreach (element_children($elements) as $key) {
    if (isset($elements[$key]) && $elements[$key]) {
685
      _form_validate($elements[$key], $form_state);
686 687
    }
  }
688
  // Validate the current input.
689
  if (!isset($elements['#validated']) || !$elements['#validated']) {
690
    if (isset($elements['#needs_validation'])) {
691 692 693 694 695
      // Make sure a value is passed when the field is required.
      // A simple call to empty() will not cut it here as some fields, like
      // checkboxes, can return a valid value of '0'. Instead, check the
      // length if it's a string, and the item count if it's an array.
      if ($elements['#required'] && (!count($elements['#value']) || (is_string($elements['#value']) && strlen(trim($elements['#value'])) == 0))) {
696
        form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
697
      }
698

699 700
      // Verify that the value is not longer than #maxlength.
      if (isset($elements['#maxlength']) && drupal_strlen($elements['#value']) > $elements['#maxlength']) {
701
        form_error($elements, $t('!name cannot be longer than %max characters but is currently %length characters long.', array('!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title'], '%max' => $elements['#maxlength'], '%length' => drupal_strlen($elements['#value']))));
702 703
      }

704
      if (isset($elements['#options']) && isset($elements['#value'])) {
705 706 707 708 709 710 711 712 713 714
        if ($elements['#type'] == 'select') {
          $options = form_options_flatten($elements['#options']);
        }
        else {
          $options = $elements['#options'];
        }
        if (is_array($elements['#value'])) {
          $value = $elements['#type'] == 'checkboxes' ? array_keys(array_filter($elements['#value'])) : $elements['#value'];
          foreach ($value as $v) {
            if (!isset($options[$v])) {
715
              form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
716
              watchdog('form', 'Illegal choice %choice in !name element.', array('%choice' => $v, '!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
717
            }
718 719
          }
        }
720
        elseif (!isset($options[$elements['#value']])) {
721
          form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
722
          watchdog('form', 'Illegal choice %choice in %name element.', array('%choice' => $elements['#value'], '%name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
723
        }
724 725 726
      }
    }

727 728 729
    // Call user-defined form level validators and store a copy of the full
    // form so that element-specific validators can examine the entire structure
    // if necessary.
730 731
    if (isset($form_id)) {
      form_execute_handlers('validate', $elements, $form_state);
732
      $complete_form = $elements;
733 734 735 736 737
    }
    // Call any element-specific validators. These must act on the element
    // #value data.
    elseif (isset($elements['#element_validate'])) {
      foreach ($elements['#element_validate'] as $function) {
738
        if (function_exists($function))  {
739
          $function($elements, $form_state, $complete_form);
740 741 742
        }
      }
    }
743
    $elements['#validated'] = TRUE;
744 745 746
  }
}

747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775
/**
 * A helper function used to execute custom validation and submission
 * handlers for a given form. Button-specific handlers are checked
 * first. If none exist, the function falls back to form-level handlers.
 *
 * @param $type
 *   The type of handler to execute. 'validate' or 'submit' are the
 *   defaults used by Form API.
 * @param $form
 *   An associative array containing the structure of the form.
 * @param $form_state
 *   A keyed array containing the current state of the form. If the user
 *   submitted the form by clicking a button with custom handler functions
 *   defined, those handlers will be stored here.
 */
function form_execute_handlers($type, &$form, &$form_state) {
  $return = FALSE;
  if (isset($form_state[$type .'_handlers'])) {
    $handlers = $form_state[$type .'_handlers'];
  }
  elseif (isset($form['#'. $type])) {
    $handlers = $form['#'. $type];
  }
  else {
    $handlers = array();
  }

  foreach ($handlers as $function) {
    if (function_exists($function))  {
776 777 778 779
      // Check to see if a previous _submit handler has set a batch, but 
      // make sure we do not react to a batch that is already being processed 
      // (for instance if a batch operation performs a drupal_execute()).
      if ($type == 'submit' && ($batch =& batch_get()) && !isset($batch['current_set'])) {
780 781 782
        // Some previous _submit handler has set a batch. We store the call
        // in a special 'control' batch set, for execution at the correct
        // time during the batch processing workflow.
783
        $batch['sets'][] = array('form_submit' => $function);
784 785
      }
      else {
786
        $function($form, $form_state);
787 788 789 790 791 792 793
      }
      $return = TRUE;
    }
  }
  return $return;
}

794
/**
795 796 797 798 799 800 801 802 803
 * File an error against a form element.
 *
 * @param $name
 *   The name of the form element. If the #parents property of your form
 *   element is array('foo', 'bar', 'baz') then you may set an error on 'foo'
 *   or 'foo][bar][baz'. Setting an error on 'foo' sets an error for every
 *   element where the #parents array starts with 'foo'.
 * @param $message
 *   The error message to present to the user.
804 805
 * @param $reset
 *   Reset the form errors static cache.
806 807 808
 * @return
 *   Never use the return value of this function, use form_get_errors and
 *   form_get_error instead.
809
 */
810
function form_set_error($name = NULL, $message = '', $reset = FALSE) {
811
  static $form = array();
812 813 814
  if ($reset) {
    $form = array();
  }
815 816
  if (isset($name) && !isset($form[$name])) {
    $form[$name] = $message;
817 818 819
    if ($message) {
      drupal_set_message($message, 'error');
    }
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848
  }
  return $form;
}

/**
 * Return an associative array of all errors.
 */
function form_get_errors() {
  $form = form_set_error();
  if (!empty($form)) {
    return $form;
  }
}

/**
 * Return the error message filed against the form with the specified name.
 */
function form_get_error($element) {
  $form = form_set_error();
  $key = $element['#parents'][0];
  if (isset($form[$key])) {
    return $form[$key];
  }
  $key = implode('][', $element['#parents']);
  if (isset($form[$key])) {
    return $form[$key];
  }
}

849 850 851
/**
 * Flag an element as having an error.
 */
852
function form_error(&$element, $message = '') {
853
  form_set_error(implode('][', $element['#parents']), $message);
854 855 856
}

/**
857 858 859
 * Walk through the structured form array, adding any required
 * properties to each element and mapping the incoming $_POST
 * data to the proper elements.
860 861
 *
 * @param $form_id
862 863
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
864 865
 * @param $form
 *   An associative array containing the structure of the form.
866 867 868 869 870
 * @param $form_state
 *   A keyed array containing the current state of the form. In this
 *   context, it is used to accumulate information about which button
 *   was clicked when the form was submitted, as well as the sanitized
 *   $_POST data.
871
 */
872
function form_builder($form_id, $form, &$form_state) {
873
  static $complete_form, $cache;
874

875 876 877
  // Initialize as unprocessed.
  $form['#processed'] = FALSE;

878
  // Use element defaults.
879
  if ((!empty($form['#type'])) && ($info = _element_info($form['#type']))) {
880
    // Overlay $info onto $form, retaining preexisting keys in $form.
881 882 883
    $form += $info;
  }

884
  if (isset($form['#type']) && $form['#type'] == 'form') {
885
    $cache = NULL;
886 887 888 889
    $complete_form = $form;
    if (!empty($form['#programmed'])) {
      $form_state['submitted'] = TRUE;
    }
890 891
  }

892
  if (isset($form['#input']) && $form['#input']) {
893
    _form_builder_handle_input_element($form_id, $form, $form_state, $complete_form);
894
  }
895
  $form['#defaults_loaded'] = TRUE;
896

897 898 899
  // We start off assuming all form elements are in the correct order.
  $form['#sorted'] = TRUE;

900
  // Recurse through all child elements.
901
  $count = 0;
902
  foreach (element_children($form) as $key) {
903 904
    $form[$key]['#post'] = $form['#post'];
    $form[$key]['#programmed'] = $form['#programmed'];
905
    // Don't squash an existing tree value.
906 907 908
    if (!isset($form[$key]['#tree'])) {
      $form[$key]['#tree'] = $form['#tree'];
    }
909

910
    // Deny access to child elements if parent is denied.
911 912 913 914
    if (isset($form['#access']) && !$form['#access']) {
      $form[$key]['#access'] = FALSE;
    }

915
    // Don't squash existing parents value.
916
    if (!isset($form[$key]['#parents'])) {
917 918
      // Check to see if a tree of child elements is present. If so,
      // continue down the tree if required.
919
      $form[$key]['#parents'] = $form[$key]['#tree'] && $form['#tree'] ? array_merge($form['#parents'], array($key)) : array($key);
920 921 922
      $array_parents = isset($form['#array_parents']) ? $form['#array_parents'] : array();
      $array_parents[] = $key;
      $form[$key]['#array_parents'] = $array_parents;
923 924
    }

925
    // Assign a decimal placeholder weight to preserve original array order.
926 927 928
    if (!isset($form[$key]['#weight'])) {
      $form[$key]['#weight'] = $count/1000;
    }
929
    else {
930 931
      // If one of the child elements has a weight then we will need to sort
      // later.
932 933
      unset($form['#sorted']);
    }
934
    $form[$key] = form_builder($form_id, $form[$key], $form_state);
935 936 937
    $count++;
  }

938 939
  // The #after_build flag allows any piece of a form to be altered
  // after normal input parsing has been completed.
940 941
  if (isset($form['#after_build']) && !isset($form['#after_build_done'])) {
    foreach ($form['#after_build'] as $function) {
942
      $form = $function($form, $form_state);
943 944 945 946 947
      $form['#after_build_done'] = TRUE;
    }
  }

  // Now that we've processed everything, we can go back to handle the funky
948
  // Internet Explorer button-click scenario.
949
  _form_builder_ie_cleanup($form, $form_state);
950

951 952 953 954 955 956 957
  // We shoud keep the buttons array until the IE clean up function
  // has recognized the submit button so the form has been marked
  // as submitted. If we already know which button was submitted,
  // we don't need the array.
  if (!empty($form_state['submitted'])) {
    unset($form_state['buttons']);
  }
958

959 960
  // If some callback set #cache, we need to flip a static flag so later it
  // can be found.
961
  if (!empty($form['#cache'])) {
962 963 964 965 966 967
    $cache = $form['#cache'];
  }
  // We are on the top form, we can copy back #cache if it's set.
  if (isset($form['#type']) && $form['#type'] == 'form' && isset($cache)) {
    $form['#cache'] = TRUE;
  }
968 969 970 971 972 973 974 975
  return $form;
}

/**
 * Populate the #value and #name properties of input elements so they
 * can be processed and rendered. Also, execute any #process handlers
 * attached to a specific element.
 */
976
function _form_builder_handle_input_element($form_id, &$form, &$form_state, $complete_form) {
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999
  if (!isset($form['#name'])) {
    $name = array_shift($form['#parents']);
    $form['#name'] = $name;
    if ($form['#type'] == 'file') {
      // To make it easier to handle $_FILES in file.inc, we place all
      // file fields in the 'files' array. Also, we do not support
      // nested file names.
      $form['#name'] = 'files['. $form['#name'] .']';
    }
    elseif (count($form['#parents'])) {
      $form['#name'] .= '['. implode('][', $form['#parents']) .']';
    }
    array_unshift($form['#parents'], $name);
  }
  if (!isset($form['#id'])) {
    $form['#id'] = form_clean_id('edit-'. implode('-', $form['#parents']));
  }

  if (!empty($form['#disabled'])) {
    $form['#attributes']['disabled'] = 'disabled';
  }

  if (!isset($form['#value']) && !array_key_exists('#value', $form)) {
1000
    $function = !empty($form['#value_callback']) ? $form['#value_callback'] : 'form_type_'. $form['#type'] .'_value';
1001 1002 1003 1004 1005 1006
    if (($form['#programmed']) || ((!isset($form['#access']) || $form['#access']) && isset($form['#post']) && (isset($form['#post']['form_id']) && $form['#post']['form_id'] == $form_id))) {
      $edit = $form['#post'];
      foreach ($form['#parents'] as $parent) {
        $edit = isset($edit[$parent]) ? $edit[$parent] : NULL;
      }
      if (!$form['#programmed'] || isset($edit)) {
1007 1008 1009
        // Call #type_value to set the form value;
        if (function_exists($function)) {
          $form['#value'] = $function($form, $edit);
1010
        }
1011 1012
        if (!isset($form['#value']) && isset($edit)) {
          $form['#value'] = $edit;
1013 1014
        }
      }
1015 1016 1017 1018
      // Mark all posted values for validation.
      if (isset($form['#value']) || (isset($form['#required']) && $form['#required'])) {
        $form['#needs_validation'] = TRUE;
      }
1019
    }
1020
    // Load defaults.
1021
    if (!isset($form['#value'])) {
1022
      // Call #type_value without a second argument to request default_value handling.
1023
      if (function_exists($function)) {
1024
        $form['#value'] = $function($form);
1025
      }
1026
      // Final catch. If we haven't set a value yet, use the explicit default value.
1027 1028 1029
      // Avoid image buttons (which come with garbage value), so we only get value
      // for the button actually clicked.
      if (!isset($form['#value']) && empty($form['#has_garbage_value'])) {
1030
        $form['#value'] = isset($form['#default_value']) ? $form['#default_value'] : '';
1031 1032
      }
    }
1033
  }
1034

1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
  // Determine which button (if any) was clicked to submit the form.
  // We compare the incoming values with the buttons defined in the form,
  // and flag the one that matches. We have to do some funky tricks to
  // deal with Internet Explorer's handling of single-button forms, though.
  if (!empty($form['#post']) && isset($form['#executes_submit_callback'])) {
    // First, accumulate a collection of buttons, divided into two bins:
    // those that execute full submit callbacks and those that only validate.
    $button_type = $form['#executes_submit_callback'] ? 'submit' : 'button';
    $form_state['buttons'][$button_type][] = $form;

1045
    if (_form_button_was_clicked($form)) {
1046 1047 1048 1049 1050 1051
      $form_state['submitted'] = $form_state['submitted'] || $form['#executes_submit_callback'];

      // In most cases, we want to use form_set_value() to manipulate
      // the global variables. In this special case, we want to make sure that
      // the value of this element is listed in $form_variables under 'op'.
      $form_state['values'][$form['#name']] = $form['#value'];
1052
      $form_state['clicked_button'] = $form;
1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066

      if (isset($form['#validate'])) {
        $form_state['validate_handlers'] = $form['#validate'];
      }
      if (isset($form['#submit'])) {
        $form_state['submit_handlers'] = $form['#submit'];
      }
    }
  }
  // Allow for elements to expand to multiple elements, e.g., radios,
  // checkboxes and files.
  if (isset($form['#process']) && !$form['#processed']) {
    foreach ($form['#process'] as $process) {
      if (function_exists($process)) {
1067
        $form = $process($form, isset($edit) ? $edit : NULL, $form_state, $complete_form);
1068 1069 1070 1071 1072 1073 1074
      }
    }
    $form['#processed'] = TRUE;
  }
  form_set_value($form, $form['#value'], $form_state);
}

1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132
/**
 * Helper function to handle the sometimes-convoluted logic of button
 * click detection.
 *
 * In Internet Explorer, if ONLY one submit button is present, AND the
 * enter key is used to submit the form, no form value is sent for it
 * and we'll never detect a match. That special case is handled by
 * _form_builder_ie_cleanup().
 */
function _form_button_was_clicked($form) {
  // First detect normal 'vanilla' button clicks. Traditionally, all
  // standard buttons on a form share the same name (usually 'op'),
  // and the specific return value is used to determine which was
  // clicked. This ONLY works as long as $form['#name'] puts the
  // value at the top level of the tree of $_POST data.
  if (isset($form['#post'][$form['#name']]) && $form['#post'][$form['#name']] == $form['#value']) {
    return TRUE;
  }
  // When image buttons are clicked, browsers do NOT pass the form element
  // value in $_POST. Instead they pass an integer representing the
  // coordinates of the click on the button image. This means that image
  // buttons MUST have unique $form['#name'] values, but the details of
  // their $_POST data should be ignored.
  elseif (!empty($form['#has_garbage_value']) && isset($form['#value']) && $form['#value'] !== '') {
    return TRUE;
  }
  return FALSE;
}

/**
 * In IE, if only one submit button is present, AND the enter key is
 * used to submit the form, no form value is sent for it and our normal
 * button detection code will never detect a match. We call this
 * function after all other button-detection is complete to check
 * for the proper conditions, and treat the single button on the form
 * as 'clicked' if they are met.
 */
function _form_builder_ie_cleanup($form, &$form_state) {
  // Quick check to make sure we're always looking at the full form
  // and not a sub-element.
  if (!empty($form['#type']) && $form['#type'] == 'form') {
    // If we haven't recognized a submission yet, and there's a single
    // submit button, we know that we've hit the right conditions. Grab
    // the first one and treat it as the clicked button.
    if (empty($form_state['submitted']) && !empty($form_state['buttons']['submit']) && empty($form_state['buttons']['button'])) {
      $button = $form_state['buttons']['submit'][0];

      // Set up all the $form_state information that would have been
      // populated had the button been recognized earlier.
      $form_state['submitted'] = TRUE;
      $form_state['submit_handlers'] = empty($button['#submit']) ? NULL : $button['#submit'];
      $form_state['validate_handlers'] = empty($button['#validate']) ? NULL : $button['#validate'];
      $form_state['values'][$button['#name']] = $button['#value'];
      $form_state['clicked_button'] = $button;
    }
  }
}

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/**
 * Helper function to determine the value for an image button form element.
 *
 * @param $form
 *   The form element whose value is being populated.
 * @param $edit
 *   The incoming POST data to populate the form element. If this is FALSE,
 *   the element's default value should be returned.
 * @return
 *   The data that will appear in the $form_state['values'] collection
 *   for this element. Return nothing to use the default.
 */
function form_type_image_button_value($form, $edit = FALSE) {
  if ($edit !== FALSE) {
    if (!empty($edit)) {
      // If we're dealing with Mozilla or Opera, we're lucky. It will
      // return a proper value, and we can get on with things.
      return $form['#return_value'];
    }
    else {
      // Unfortunately, in IE we never get back a proper value for THIS
      // form element. Instead, we get back two split values: one for the
      // X and one for the Y coordinates on which the user clicked the
      // button. We'll find this element in the #post data, and search
      // in the same spot for its name, with '_x'.
      $post = $form['#post'];
      foreach (split('\[', $form['#name']) as $element_name) {
        // chop off the ] that may exist.
        if (substr($element_name, -1) == ']') {
          $element_name = substr($element_name, 0, -1);
        }

        if (!isset($post[$element_name])) {
          if (isset($post[$element_name .'_x'])) {
            return $form['#return_value'];
          }
          return NULL;
        }
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        $post = $post[$element_name];
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      }
      return $form['#return_value'];
    }
  }
}

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/**
 * Helper function to determine the value for a checkbox form element.
 *
 * @param $form
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 *   The form element whose value is being populated.
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 * @param $edit
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 *   The incoming POST data to populate the form element. If this is FALSE,
 *   the element's default value should be returned.
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 * @return
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 *   The data that will appear in the $form_state['values'] collection
 *   for this element. Return nothing to use the default.
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 */
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function form_type_checkbox_value($form, $edit = FALSE) {
  if ($edit !== FALSE) {
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    if (empty($form['#disabled'])) {
      return !empty($edit) ? $form['#return_value'] : 0;
    }
    else {
      return $form['#default_value'];
    }
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  }
}

/**
 * Helper function to determine the value for a checkboxes form element.
 *
 * @param $form
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 *   The form element whose value is being populated.
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 * @param $edit