form.inc 104 KB
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<?php
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// $Id$

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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 reference @endlink
 * and the @link http://api.drupal.org/api/file/developer/topics/forms_api.html quickstart guide. @endlink
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 */

/**
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 * Wrapper for drupal_build_form() for use when $form_state is not needed.
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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 different $form_id values to the
 *   proper form constructor function. Examples may be found in node_forms(),
 *   search_forms(), and user_forms().
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 * @param ...
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 *   Any additional arguments are passed on to the functions called by
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 *   drupal_get_form(), including the unique form constructor function. For
 *   example, the node_edit form requires that a node object is passed in here
 *   when it is called.
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 * @return
 *   The rendered form.
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 *
 * @see drupal_build_form()
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 */
function drupal_get_form($form_id) {
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  $form_state = array();
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  $args = func_get_args();
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  // Remove $form_id from the arguments.
  array_shift($args);
  $form_state['args'] = $args;

  return drupal_build_form($form_id, $form_state);
}

/**
 * Build, render, and process a form based on a form id.
 *
 * The form may also be retrieved from the cache if the form was built in a
 * previous page-load. The form is then passed on for processing, validation
 * and submission if there is proper input, and then rendered for display
 * if necessary.
 *
 * @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
 *   An array which stores information about the form. This is passed as a
 *   reference so that the caller can use it to examine what the form changed
 *   when the form submission process is complete.
 *
 *   The following parameters may be set in $form_state to affect how the form
 *   is rendered:
 *   - args: An array of arguments to pass to the form builder.
 *   - input: An array of input that corresponds to $_POST or $_GET, depending
 *     on the 'method' chosen (see below).
 *   - method: The HTTP form method to use for finding the input for this form.
 *     May be 'post' or 'get'. Defaults to 'post'. Note that 'get' method
 *     forms do not use form ids so are always considered to be submitted, which
 *     can have unexpected effects. The 'get' method should only be used on
 *     forms that do not change data, as that is exclusively the domain of post.
 *   - rerender: May be set to FALSE to force the form to not be re-rendered
 *     after submit. Ordinarily, forms are re-rendered after a successful submit
 *     if there is no redirect. However, many forms may want to perform some
 *     other action, but not necessarily re-render the form. This is
 *     particularly true when using AHAH or AJAX where some data may be returned
 *     to the calling JavaScript. Note that a form validation error will always
 *     re-render the form.
 *   - no_redirect: If set to TRUE the form will NOT perform a drupal_goto(),
 *     even if a redirect is set.
 *   - always_process: If TRUE and the method is GET, a form_id is not
 *     necessary. This should only be used on RESTful GET forms that do NOT
 *     write data, as this could lead to security issues. It is useful so that
 *     searches do not need to have a form_id in their query arguments to
 *     trigger the search.
 *   - must_validate: Ordinarily, a form is only validated once but there are
 *     times when a form is resubmitted internally and should be validated
 *     again. Setting this to TRUE will force that to happen. This is most
 *     likely to occur during AHAH or AJAX operations.
 * @return
 *   The rendered form or NULL, depending upon the $form_state flags that were set.
 */
function drupal_build_form($form_id, &$form_state) {
  // Ensure some defaults; if already set they will not be overridden.
  $form_state += form_state_defaults();

  if (!isset($form_state['input'])) {
    $form_state['input'] = $form_state['method'] == 'get' ? $_GET : $_POST;
  }

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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 input contains a form_build_id, we'll check the
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    // 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.
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    if (isset($form_state['input']['form_id']) && $form_state['input']['form_id'] == $form_id && !empty($form_state['input']['form_build_id'])) {
      $form = form_get_cache($form_state['input']['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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      $form = drupal_retrieve_form($form_id, $form_state);
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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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      // Fix the form method, if it is 'get' in $form_state, but not in $form.
      if ($form_state['method'] == 'get' && !isset($form['#method'])) {
        $form['#method'] = 'get';
      }

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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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    }
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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, $form_state);
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    // If we were told not to redirect, but not told to re-render, return here.
    if (!empty($form_state['executed']) && empty($form_state['rerender'])) {
      return;
    }

    if ($cacheable && !empty($form['#cache']) && empty($form['#no_cache'])) {
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      // Caching is done past drupal_process_form so #process callbacks can
      // set #cache. By not sending the form state, we avoid storing
      // $form_state['storage'].
      form_set_cache($form_build_id, $original_form, NULL);
    }
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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.
  //
  // If $form_state['storage'] or $form_state['rebuild'] have been
  // set by any submit or validate handlers, however, we know that
  // we're in a complex multi-part process of some sort and the form's
  // workflow is NOT 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().

  if (!empty($form_state['rebuild']) || !empty($form_state['storage'])) {
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    $form = drupal_rebuild_form($form_id, $form_state);
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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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/**
 * Retrieve default values for the $form_state array.
 */
function form_state_defaults() {
  return array(
    'storage' => NULL,
    'submitted' => FALSE,
    'method' => 'post',
    'rerender' => TRUE,
    'programmed' => FALSE,
  );
}

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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.
 *
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 * When getting a form from the cache, the $form_id must be shifted off from
 * $form['#args'], so the resulting array can be given to $form_state['args'].
 *
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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
 *   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 $form_build_id
 *   If the AHAH callback calling this function only alters part of the form,
 *   then pass in the existing form_build_id so we can re-cache with the same
 *   csid.
 * @return
 *   The newly built form.
 */
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function drupal_rebuild_form($form_id, &$form_state, $form_build_id = NULL) {
  $form = drupal_retrieve_form($form_id, $form_state);
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  if (!isset($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(mt_rand());
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  }
  $form['#build_id'] = $form_build_id;
  drupal_prepare_form($form_id, $form, $form_state);

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  if (empty($form['#no_cache'])) {
    // We cache the form structure so it can be retrieved later for validation.
    // If $form_state['storage'] is populated, we also cache it so that it can
    // be used to resume complex multi-step processes.
    form_set_cache($form_build_id, $form, $form_state);
  }
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  // 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.
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  $form_state['input'] = array();

  // Do not call drupal_process_form(), since it would prevent the rebuilt form
  // to submit.
  $form = form_builder($form_id, $form, $form_state);
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  return $form;
}

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/**
 * Fetch a form from cache.
 */
function form_get_cache($form_build_id, &$form_state) {
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  if ($cached = cache_get('form_' . $form_build_id, 'cache_form')) {
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    $form = $cached->data;
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    global $user;
    if ((isset($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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    }
  }
}

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

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/**
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 * Retrieves a form using a form_id, populates it with $form_state['values'],
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 * processes it, and returns any validation errors encountered. This
 * function is the programmatic counterpart to drupal_get_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. 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:
 *
 * // register a new user
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 * $form_state = array();
 * $form_state['values']['name'] = 'robo-user';
 * $form_state['values']['mail'] = 'robouser@example.com';
 * $form_state['values']['pass'] = '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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 */
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function drupal_execute($form_id, &$form_state) {
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  if (!isset($form_state['args'])) {
    $args = func_get_args();
    array_shift($args);
    array_shift($args);
    $form_state['args'] = $args;
  }
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  $form = drupal_retrieve_form($form_id, $form_state);
  $form_state['input'] = $form_state['values'];
  $form_state['programmed'] = TRUE;
  // Merge in default values.
  $form_state += form_state_defaults();
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  drupal_prepare_form($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
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  // the constructor function itself.
  $args = $form_state['args'];
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  // We first check to see if there's a function named after the $form_id.
  // If there is, we simply pass the arguments on to it to get the form.
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  if (!drupal_function_exists($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 = $form_definition['callback'];
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      drupal_function_exists($callback);
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    }
  }
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  $args = array_merge(array(&$form_state), $args);
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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);
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  $form['#form_id'] = $form_id;
  $form['#args'] = $form_state['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();

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  // With $_GET, these forms are always submitted if requested.
  if ($form_state['method'] == 'get' && !empty($form_state['always_process'])) {
    if (!isset($form_state['input']['form_build_id'])) {
      $form_state['input']['form_build_id'] = $form['#build_id'];
    }
    if (!isset($form_state['input']['form_id'])) {
      $form_state['input']['form_id'] = $form_id;
    }
    if (!isset($form_state['input']['form_token']) && isset($form['#token'])) {
      $form_state['input']['form_token'] = drupal_get_token($form['#token']);
    }
  }

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  $form = form_builder($form_id, $form, $form_state);
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  // Only process the form if it is programmed or the form_id coming
  // from the POST data is set and matches the current form_id.
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  if ((!empty($form_state['programmed'])) || (!empty($form_state['input']) && (isset($form_state['input']['form_id']) && ($form_state['input']['form_id'] == $form_id)))) {
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    drupal_validate_form($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
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    // cache when a form is processed, so scenarios that result in
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    // 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');
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      }

      // 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
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        // late execution of submit handlers and post-batch redirection.
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        $batch['form'] = $form;
        $batch['form_state'] = $form_state;
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        $batch['progressive'] = !$form_state['programmed'];
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        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 $form_state bundle itself.
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      if (!$form_state['programmed'] && empty($form_state['rebuild']) && empty($form_state['storage'])) {
        if (!empty($form_state['no_redirect'])) {
          $form_state['executed'] = TRUE;
        }
        else {
          drupal_redirect_form($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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  $form_state['programmed'] = isset($form_state['programmed']) ? $form_state['programmed'] : FALSE;
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  if (isset($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 || $form_state['programmed']) {
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      unset($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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  elseif (isset($user->uid) && $user->uid && !$form_state['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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  $form += array('#tree' => FALSE, '#parents' => array());
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  if (!isset($form['#validate'])) {
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    if (drupal_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($form['#submit'])) {
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    if (drupal_function_exists($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);
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  drupal_alter('form_' . $form_id, $data);
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  // __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);
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}

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/**
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 * Validates user-submitted form data from the $form_state using
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 * 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.
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 * @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'] = $data;
 *   This technique is useful when validation requires file parsing,
 *   web service requests, or other expensive requests that should
 *   not be repeated in the submission step.
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 */
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function drupal_validate_form($form_id, $form, &$form_state) {
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  static $validated_forms = array();

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  if (isset($validated_forms[$form_id]) && empty($form_state['must_validate'])) {
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    return;
  }
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  // If the session token was set by drupal_prepare_form(), ensure that it
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  // matches the current user's session.
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  if (isset($form['#token'])) {
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    if (!drupal_valid_token($form_state['values']['form_token'], $form['#token'])) {
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      // Setting this error will cause the form to fail validation.
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      form_set_error('form_token', t('Validation error, please try again. If this error persists, please contact the site administrator.'));
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    }
  }

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  _form_validate($form, $form_state, $form_id);
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  $validated_forms[$form_id] = TRUE;
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}

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/**
 * 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 $form
 *   An associative array containing the structure of the form.
 * @return
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 *   A string containing the themed HTML.
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 */
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function drupal_render_form($form_id, &$form) {
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  // Don't override #theme if someone already set it.
  if (!isset($form['#theme'])) {
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    init_theme();
    $registry = theme_get_registry();
    if (isset($registry[$form_id])) {
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      $form['#theme'] = $form_id;
    }
  }

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  $output = drupal_render($form);
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  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 $redirect
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 *   An optional value containing the destination path to redirect
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 *   to if none is specified by the form.
 */
function drupal_redirect_form($form, $redirect = NULL) {
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  $goto = NULL;
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  if (isset($redirect)) {
    $goto = $redirect;
  }
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  if ($goto !== FALSE && isset($form['#redirect'])) {
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    $goto = $form['#redirect'];
  }
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  if (!isset($goto) || ($goto !== FALSE)) {
    if (isset($goto)) {
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      // Remove any fake destination set by drupal_not_found() or
      // drupal_access_denied() so that we can properly redirect from those
      // pages.
      if (isset($_REQUEST['destination']) && $_REQUEST['destination'] == $_GET['q']) {
        unset($_REQUEST['destination']);
      }
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      if (is_array($goto)) {
        call_user_func_array('drupal_goto', $goto);
      }
      else {
        drupal_goto($goto);
      }
    }
    drupal_goto($_GET['q']);
  }
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}

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/**
 * 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.
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 * @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.
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 * @param $form_id
 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
 */
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function _form_validate($elements, &$form_state, $form_id = NULL) {
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  static $complete_form;

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  // Also used in the installer, pre-database setup.
  $t = get_t();
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  // Recurse through all children.
  foreach (element_children($elements) as $key) {
    if (isset($elements[$key]) && $elements[$key]) {
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      _form_validate($elements[$key], $form_state);
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    }
  }
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  // Validate the current input.
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  if (!isset($elements['#validated']) || !$elements['#validated']) {
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    if (isset($elements['#needs_validation'])) {
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      // 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))) {
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        form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
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      }
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782 783
      // Verify that the value is not longer than #maxlength.
      if (isset($elements['#maxlength']) && drupal_strlen($elements['#value']) > $elements['#maxlength']) {
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        form_error($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']))));
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      }

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      if (isset($elements['#options']) && isset($elements['#value'])) {
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        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[$v])) {
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              form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
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              watchdog('form', 'Illegal choice %choice in !name element.', array('%choice' => $v, '!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
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            }
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          }
        }
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        elseif (!isset($options[$elements['#value']])) {
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          form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
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          watchdog('form', 'Illegal choice %choice in %name element.', array('%choice' => $elements['#value'], '%name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
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        }
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      }
    }

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    // 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.
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    if (isset($form_id)) {
      form_execute_handlers('validate', $elements, $form_state);
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      $complete_form = $elements;
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    }
    // Call any element-specific validators. These must act on the element
    // #value data.
    elseif (isset($elements['#element_validate'])) {
      foreach ($elements['#element_validate'] as $function) {
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        if (drupal_function_exists($function))  {
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          $function($elements, $form_state, $complete_form);
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        }
      }
    }
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    $elements['#validated'] = TRUE;
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  }
}

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/**
 * 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) {
  $return = FALSE;
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  if (isset($form_state[$type . '_handlers'])) {
    $handlers = $form_state[$type . '_handlers'];
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  }
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  elseif (isset($form['#' . $type])) {
    $handlers = $form['#' . $type];
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  }
  else {
    $handlers = array();
  }

  foreach ($handlers as $function) {
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    if (drupal_function_exists($function))  {
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      // 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'])) {
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        // 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.
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        $batch['sets'][] = array('form_submit' => $function);
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      }
      else {
869
        $function($form, $form_state);
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      }
      $return = TRUE;
    }
  }
  return $return;
}

877
/**
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 * 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.
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 * @param $reset
 *   Reset the form errors static cache.
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 * @return
 *   Never use the return value of this function, use form_get_errors and
 *   form_get_error instead.
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 */
893
function form_set_error($name = NULL, $message = '', $reset = FALSE) {
894
  static $form = array();
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  if ($reset) {
    $form = array();
  }
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  if (isset($name) && !isset($form[$name])) {
    $form[$name] = $message;
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    if ($message) {
      drupal_set_message($message, 'error');
    }
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  }
  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];
  }
}

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/**
 * Flag an element as having an error.
 */
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function form_error(&$element, $message = '') {
936
  form_set_error(implode('][', $element['#parents']), $message);
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}

/**
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 * Walk through the structured form array, adding any required
 * properties to each element and mapping the incoming $_POST
 * data to the proper elements.
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 *
 * @param $form_id
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 *   A unique string identifying the form for validation, submission,
 *   theming, and hook_form_alter functions.
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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. In this
 *   context, it is used to accumulate information about which button
 *   was clicked when the form was submitted, as well as the sanitized
 *   $_POST data.
954
 */
955
function form_builder($form_id, $form, &$form_state) {
956
  static $complete_form, $cache, $file;
957

958 959 960
  // Initialize as unprocessed.
  $form['#processed'] = FALSE;

961
  // Use element defaults.
962
  if ((!empty($form['#type'])) && ($info = element_info($form['#type']))) {
963
    // Overlay $info onto $form, retaining preexisting keys in $form.
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    $form += $info;
  }

967
  if (isset($form['#type']) && $form['#type'] == 'form') {
968
    $cache = NULL;
969
    $complete_form = $form;
970
    if (!empty($form_state['programmed'])) {
971 972
      $form_state['submitted'] = TRUE;
    }
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  }

975
  if (isset($form['#input']) && $form['#input']) {
976
    _form_builder_handle_input_element($form_id, $form, $form_state, $complete_form);
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  }
978
  $form['#defaults_loaded'] = TRUE;
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  // We start off assuming all form elements are in the correct order.
  $form['#sorted'] = TRUE;

983
  // Recurse through all child elements.
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  $count = 0;
985
  foreach (element_children($form) as $key) {
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    // Don't squash an existing tree value.
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    if (!isset($form[$key]['#tree'])) {
      $form[$key]['#tree'] = $form['#tree'];
    }
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    // Deny access to child elements if parent is denied.
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    if (isset($form['#access']) && !$form['#access']) {
      $form[$key]['#access'] = FALSE;
    }

996
    // Don't squash existing parents value.
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    if (!isset($form[$key]['#parents'])) {
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      // Check to see if a tree of child elements is present. If so,
      // continue down the tree if required.
1000
      $form[$key]['#parents'] = $form[$key]['#tree'] && $form['#tree'] ? array_merge($form['#parents'], array($key)) : array($key);
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      $array_parents = isset($form['#array_parents']) ? $form['#array_parents'] : array();
      $array_parents[] = $key;
      $form[$key]['#array_parents'] = $array_parents;
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    }

1006
    // Assign a decimal placeholder weight to preserve original array order.
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    if (!isset($form[$key]['#weight'])) {
      $form[$key]['#weight'] = $count/1000;
    }
1010
    else {
1011 1012
      // If one of the child elements has a weight then we will need to sort
      // later.
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      unset($form['#sorted']);
    }
1015
    $form[$key] = form_builder($form_id, $form[$key], $form_state);
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    $count++;
  }

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  // The #after_build flag allows any piece of a form to be altered
  // after normal input parsing has been completed.
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  if (isset($form['#after_build']) && !isset($form['#after_build_done'])) {
    foreach ($form['#after_build'] as $function) {
1023
      $form = $function($form, $form_state);
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      $form['#after_build_done'] = TRUE;
    }
  }

  // Now that we've processed everything, we can go back to handle the funky
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  // Internet Explorer button-click scenario.
1030
  _form_builder_ie_cleanup($form, $form_state);
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  // We should keep the buttons array until the IE clean up function
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  // has recognized the submit button so the form has been marked
  // as submitted. If we already know which button was submitted,
  // we don't need the array.
  if (!empty($form_state['submitted'])) {
    unset($form_state['buttons']);
  }
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1040 1041
  // If some callback set #cache, we need to flip a static flag so later it
  // can be found.
1042
  if (!empty($form['#cache'])) {
1043 1044
    $cache = $form['#cache'];
  }
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  // If there is a file element, we need to flip a static flag so later the
  // form encoding can be set.
1047
  if (isset($form['#type']) && $form['#type'] == 'file') {
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    $file = TRUE;
  }
  if (isset($form['#type']) && $form['#type'] == 'form') {
    // We are on the top form, we can copy back #cache if it's set.
    if (isset($cache)) {
      $form['#cache'] = TRUE;
    }
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    // If there is a file element, we set the form encoding.
    if (isset($file)) {
      $form['#attributes']['enctype'] = 'multipart/form-data';
    }
1059
  }
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  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.
 */
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function _form_builder_handle_input_element($form_id, &$form, &$form_state, $complete_form) {
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  if (!isset($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.
1076
      $form['#name'] = 'files[' . $form['#name'] . ']';
1077 1078
    }
    elseif (count($form['#parents'])) {
1079
      $form['#name'] .= '[' . implode('][', $form['#parents']) . ']';
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    }
    array_unshift($form['#parents'], $name);
  }
  if (!isset($form['#id'])) {
1084
    $form['#id'] = form_clean_id('edit-' . implode('-', $form['#parents']));
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  }

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

  if (!isset($form['#value']) && !array_key_exists('#value', $form)) {
1092
    $function = !empty($form['#value_callback']) ? $form['#value_callback'] : 'form_type_' . $form['#type'] . '_value';
1093 1094
    if (($form_state['programmed']) || ((!isset($form['#access']) || $form['#access']) && isset($form_state['input']) && (isset($form_state['input']['form_id']) && $form_state['input']['form_id'] == $form_id))) {
      $edit = $form_state['input'];
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      foreach ($form['#parents'] as $parent) {
        $edit = isset($edit[$parent]) ? $edit[$parent] : NULL;
      }
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      if (!$form_state['programmed'] || isset($edit)) {
1099 1100
        // Call #type_value to set the form value;
        if (function_exists($function)) {
1101
          $form['#value'] = $function($form, $edit, $form_state);
1102
        }
1103 1104
        if (!isset($form['#value']) && isset($edit)) {
          $form['#value'] = $edit;
1105 1106
        }
      }
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      // Mark all posted values for validation.
      if (isset($form['#value']) || (isset($form['#required']) && $form['#required'])) {
        $form['#needs_validation'] = TRUE;
      }
1111
    }
1112
    // Load defaults.
1113
    if (!isset($form['#value'])) {
1114
      // Call #type_value without a second argument to request default_value handling.
1115
      if (function_exists($function)) {
1116
        $form['#value'] = $function($form);
1117
      }
1118
      // Final catch. If we haven't set a value yet, use the explicit default value.
1119 1120 1121
      // 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'])) {
1122
        $form['#value'] = isset($form['#default_value']) ? $form['#default_value'] : '';
1123 1124
      }
    }
1125
  }
1126

1127 1128 1129 1130
  // 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.
1131
  if (!empty($form_state['input']) && isset($form['#executes_submit_callback'])) {
1132 1133 1134 1135 1136
    // 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;

1137
    if (_form_button_was_clicked($form, $form_state)) {
1138 1139 1140 1141 1142 1143
      $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'];
1144
      $form_state['clicked_button'] = $form;
1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157

      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 $process) {
1158
      if (drupal_function_exists($process)) {
1159
        $form = $process($form, isset($edit) ? $edit : NULL, $form_state, $complete_form);
1160 1161 1162 1163 1164 1165 1166
      }
    }
    $form['#processed'] = TRUE;
  }
  form_set_value($form, $form['#value'], $form_state);
}

1167 1168 1169 1170 1171 1172 1173 1174 1175
/**
 * 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().
 */
1176
function _form_button_was_clicked($form, &$form_state) {
1177 1178 1179 1180 1181
  // 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 $_POST data.
1182
  if (isset($form_state['input'][$form['#name']]) && $form_state['input'][$form['#name']] == $form['#value']) {
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224
    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') {