comparison includes/form.inc @ 0:ff03f76ab3fe

initial version

+<?php
+ /**
+ * @file
+ * Functions for form and batch generation and processing.
+ */
+
+/**
+ * @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
+ * functions using \@see. Conversely, validate and submit functions should
+ * reference the form builder function using \@see. For examples, of this see
+ * system_modules_uninstall() or user_pass(), the latter of which has the
+ * following in its doxygen documentation:
+ *
+ * \@ingroup forms
+ * \@see user_pass_validate().
+ * \@see user_pass_submit().
+ *
+ * @}
+ */
+
+/**
+ * @defgroup form_api Form generation
+ * @{
+ * Functions to enable the processing and display of HTML forms.
+ *
+ * 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 primary function used with forms is drupal_get_form(), which is
+ * used for forms presented interactively to a user. Forms can also be built and
+ * submitted programmatically without any user input using the
+ * drupal_form_submit() function.
+ *
+ * drupal_get_form() handles retrieving, processing, and displaying a rendered
+ * HTML form for modules automatically.
+ *
+ * Here is an example of how to use drupal_get_form() and a form builder
+ * function:
+ * @code
+ * $form = drupal_get_form('my_module_example_form');
+ * ...
+ * function my_module_example_form($form, &$form_state) {
+ *   $form['submit'] = array(
+ *     '#type' => 'submit',
+ *     '#value' => t('Submit'),
+ *   );
+ *   return $form;
+ * }
+ * function my_module_example_form_validate($form, &$form_state) {
+ *   // Validation logic.
+ * }
+ * function my_module_example_form_submit($form, &$form_state) {
+ *   // Submission logic.
+ * }
+ * @endcode
+ *
+ * Or with any number of additional arguments:
+ * @code
+ * $extra = "extra";
+ * $form = drupal_get_form('my_module_example_form', $extra);
+ * ...
+ * function my_module_example_form($form, &$form_state, $extra) {
+ *   $form['submit'] = array(
+ *     '#type' => 'submit',
+ *     '#value' => $extra,
+ *   );
+ *   return $form;
+ * }
+ * @endcode
+ *
+ * The $form argument to form-related functions is a structured array containing
+ * the elements and properties of the form. For information on the array
+ * components and format, and more detailed explanations of the Form API
+ * workflow, see the
+ * @link forms_api_reference.html Form API reference @endlink
+ * and the
+ * @link http://drupal.org/node/37775 Form API documentation section. @endlink
+ * In addition, there is a set of Form API tutorials in
+ * @link form_example_tutorial.inc the Form Example Tutorial @endlink which
+ * provide basics all the way up through multistep forms.
+ *
+ * In the form builder, validation, submission, and other form functions,
+ * $form_state is the primary influence on the processing of the form and is
+ * passed by reference to most functions, so they use it to communicate with
+ * the form system and each other.
+ *
+ * See drupal_build_form() for documentation of $form_state keys.
+ */
+
+/**
+ * Returns a renderable form array for a given form ID.
+ *
+ * This function should be used instead of drupal_build_form() when $form_state
+ * is not needed (i.e., when initially rendering the form) and is often
+ * used as a menu callback.
+ *
+ * @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(),
+ *   and search_forms().
+ * @param ...
+ *   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 is passed in here
+ *   when it is called. These are available to implementations of
+ *   hook_form_alter() and hook_form_FORM_ID_alter() as the array
+ *   $form_state['build_info']['args'].
+ *
+ * @return
+ *   The form array.
+ *
+ * @see drupal_build_form()
+ */
+function drupal_get_form($form_id) {
+  $form_state = array();
+
+  $args = func_get_args();
+  // Remove $form_id from the arguments.
+  array_shift($args);
+  $form_state['build_info']['args'] = $args;
+
+  return drupal_build_form($form_id, $form_state);
+}
+
+/**
+ * Builds 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.
+ *
+ * @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(),
+ *   and search_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 in the form changed
+ *   when the form submission process is complete. Furthermore, it may be used
+ *   to store information related to the processed data in the form, which will
+ *   persist across page requests when the 'cache' or 'rebuild' flag is set.
+ *   The following parameters may be set in $form_state to affect how the form
+ *   is rendered:
+ *   - build_info: Internal. An associative array of information stored by Form
+ *     API that is necessary to build and rebuild the form from cache when the
+ *     original context may no longer be available:
+ *     - args: A list of arguments to pass to the form constructor.
+ *     - files: An optional array defining include files that need to be loaded
+ *       for building the form. Each array entry may be the path to a file or
+ *       another array containing values for the parameters 'type', 'module' and
+ *       'name' as needed by module_load_include(). The files listed here are
+ *       automatically loaded by form_get_cache(). By default the current menu
+ *       router item's 'file' definition is added, if any. Use
+ *       form_load_include() to add include files from a form constructor.
+ *     - form_id: Identification of the primary form being constructed and
+ *       processed.
+ *     - base_form_id: Identification for a base form, as declared in a
+ *       hook_forms() implementation.
+ *   - rebuild_info: Internal. Similar to 'build_info', but pertaining to
+ *     drupal_rebuild_form().
+ *   - rebuild: Normally, after the entire form processing is completed and
+ *     submit handlers have run, a form is considered to be done and
+ *     drupal_redirect_form() will redirect the user to a new page using a GET
+ *     request (so a browser refresh does not re-submit the form). However, if
+ *     'rebuild' has been set to TRUE, then a new copy of the form is
+ *     immediately built and sent to the browser, instead of a redirect. This is
+ *     used for multi-step forms, such as wizards and confirmation forms.
+ *     Normally, $form_state['rebuild'] is set by a submit handler, since it is
+ *     usually logic within a submit handler that determines whether a form is
+ *     done or requires another step. However, a validation handler may already
+ *     set $form_state['rebuild'] to cause the form processing to bypass submit
+ *     handlers and rebuild the form instead, even if there are no validation
+ *     errors.
+ *   - redirect: Used to redirect the form on submission. It may either be a
+ *     string containing the destination URL, or an array of arguments
+ *     compatible with drupal_goto(). See drupal_redirect_form() for complete
+ *     information.
+ *   - no_redirect: If set to TRUE the form will NOT perform a drupal_goto(),
+ *     even if 'redirect' is set.
+ *   - 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.'
+ *   - cache: If set to TRUE the original, unprocessed form structure will be
+ *     cached, which allows the entire form to be rebuilt from cache. A typical
+ *     form workflow involves two page requests; first, a form is built and
+ *     rendered for the user to fill in. Then, the user fills the form in and
+ *     submits it, triggering a second page request in which the form must be
+ *     built and processed. By default, $form and $form_state are built from
+ *     scratch during each of these page requests. Often, it is necessary or
+ *     desired to persist the $form and $form_state variables from the initial
+ *     page request to the one that processes the submission. 'cache' can be set
+ *     to TRUE to do this. A prominent example is an Ajax-enabled form, in which
+ *     ajax_process_form() enables form caching for all forms that include an
+ *     element with the #ajax property. (The Ajax handler has no way to build
+ *     the form itself, so must rely on the cached version.) Note that the
+ *     persistence of $form and $form_state happens automatically for
+ *     (multi-step) forms having the 'rebuild' flag set, regardless of the value
+ *     for 'cache'.
+ *   - no_cache: If set to TRUE the form will NOT be cached, even if 'cache' is
+ *     set.
+ *   - values: An associative array of values submitted to the form. The
+ *     validation functions and submit functions use this array for nearly all
+ *     their decision making. (Note that #tree determines whether the values are
+ *     a flat array or an array whose structure parallels the $form array. See
+ *     @link forms_api_reference.html Form API reference @endlink for more
+ *     information.) These are raw and unvalidated, so should not be used
+ *     without a thorough understanding of security implications. In almost all
+ *     cases, code should use the data in the 'values' array exclusively. The
+ *     most common use of this key is for multi-step forms that need to clear
+ *     some of the user input when setting 'rebuild'. The values correspond to
+ *     $_POST or $_GET, depending on the 'method' chosen.
+ *   - 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 Ajax operations.
+ *   - programmed: If TRUE, the form was submitted programmatically, usually
+ *     invoked via drupal_form_submit(). Defaults to FALSE.
+ *   - process_input: Boolean flag. TRUE signifies correct form submission.
+ *     This is always TRUE for programmed forms coming from drupal_form_submit()
+ *     (see 'programmed' key), or if the form_id coming from the $_POST data is
+ *     set and matches the current form_id.
+ *   - submitted: If TRUE, the form has been submitted. Defaults to FALSE.
+ *   - executed: If TRUE, the form was submitted and has been processed and
+ *     executed. Defaults to FALSE.
+ *   - triggering_element: (read-only) The form element that triggered
+ *     submission. This is the same as the deprecated
+ *     $form_state['clicked_button']. It is the element that caused submission,
+ *     which may or may not be a button (in the case of Ajax forms). This key is
+ *     often used to distinguish between various buttons in a submit handler,
+ *     and is also used in Ajax handlers.
+ *   - clicked_button: Deprecated. Use triggering_element instead.
+ *   - has_file_element: Internal. If TRUE, there is a file element and Form API
+ *     will set the appropriate 'enctype' HTML attribute on the form.
+ *   - groups: Internal. An array containing references to fieldsets to render
+ *     them within vertical tabs.
+ *   - storage: $form_state['storage'] is not a special key, and no specific
+ *     support is provided for it in the Form API. By tradition it was
+ *     the location where application-specific data was stored for communication
+ *     between the submit, validation, and form builder functions, especially
+ *     in a multi-step-style form. Form implementations may use any key(s)
+ *     within $form_state (other than the keys listed here and other reserved
+ *     ones used by Form API internals) for this kind of storage. The
+ *     recommended way to ensure that the chosen key doesn't conflict with ones
+ *     used by the Form API or other modules is to use the module name as the
+ *     key name or a prefix for the key name. For example, the Node module uses
+ *     $form_state['node'] in node editing forms to store information about the
+ *     node being edited, and this information stays available across successive
+ *     clicks of the "Preview" button as well as when the "Save" button is
+ *     finally clicked.
+ *   - buttons: A list containing copies of all submit and button elements in
+ *     the form.
+ *   - complete form: A reference to the $form variable containing the complete
+ *     form structure. #process, #after_build, #element_validate, and other
+ *     handlers being invoked on a form element may use this reference to access
+ *     other information in the form the element is contained in.
+ *   - temporary: An array holding temporary data accessible during the current
+ *     page request only. All $form_state properties that are not reserved keys
+ *     (see form_state_keys_no_cache()) persist throughout a multistep form
+ *     sequence. Form API provides this key for modules to communicate
+ *     information across form-related functions during a single page request.
+ *     It may be used to temporarily save data that does not need to or should
+ *     not be cached during the whole form workflow; e.g., data that needs to be
+ *     accessed during the current form build process only. There is no use-case
+ *     for this functionality in Drupal core.
+ *   - wrapper_callback: Modules that wish to pre-populate certain forms with
+ *     common elements, such as back/next/save buttons in multi-step form
+ *     wizards, may define a form builder function name that returns a form
+ *     structure, which is passed on to the actual form builder function.
+ *     Such implementations may either define the 'wrapper_callback' via
+ *     hook_forms() or have to invoke drupal_build_form() (instead of
+ *     drupal_get_form()) on their own in a custom menu callback to prepare
+ *     $form_state accordingly.
+ *   Information on how certain $form_state properties control redirection
+ *   behavior after form submission may be found in drupal_redirect_form().
+ *
+ * @return
+ *   The rendered form. This function may also perform a redirect and hence may
+ *   not return at all, depending upon the $form_state flags that were set.
+ *
+ * @see drupal_redirect_form()
+ */
+function drupal_build_form($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 : $_POST;
+  }
+
+  if (isset($_SESSION['batch_form_state'])) {
+    // We've been redirected here after a batch processing. The form has
+    // already been processed, but needs to be rebuilt. See _batch_finished().
+    $form_state = $_SESSION['batch_form_state'];
+    unset($_SESSION['batch_form_state']);
+    return drupal_rebuild_form($form_id, $form_state);
+  }
+
+  // If the incoming input 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.
+  $check_cache = isset($form_state['input']['form_id']) && $form_state['input']['form_id'] == $form_id && !empty($form_state['input']['form_build_id']);
+  if ($check_cache) {
+    $form = form_get_cache($form_state['input']['form_build_id'], $form_state);
+  }
+
+  // If the previous bit of code didn't result in a populated $form object, we
+  // are hitting the form for the first time and we need to build it from
+  // scratch.
+  if (!isset($form)) {
+    // If we attempted to serve the form from cache, uncacheable $form_state
+    // keys need to be removed after retrieving and preparing the form, except
+    // any that were already set prior to retrieving the form.
+    if ($check_cache) {
+      $form_state_before_retrieval = $form_state;
+    }
+
+    $form = drupal_retrieve_form($form_id, $form_state);
+    drupal_prepare_form($form_id, $form, $form_state);
+
+    // form_set_cache() removes uncacheable $form_state keys defined in
+    // form_state_keys_no_cache() in order for multi-step forms to work
+    // properly. This means that form processing logic for single-step forms
+    // using $form_state['cache'] may depend on data stored in those keys
+    // during drupal_retrieve_form()/drupal_prepare_form(), but form
+    // processing should not depend on whether the form is cached or not, so
+    // $form_state is adjusted to match what it would be after a
+    // form_set_cache()/form_get_cache() sequence. These exceptions are
+    // allowed to survive here:
+    // - always_process: Does not make sense in conjunction with form caching
+    //   in the first place, since passing form_build_id as a GET parameter is
+    //   not desired.
+    // - temporary: Any assigned data is expected to survives within the same
+    //   page request.
+    if ($check_cache) {
+      $uncacheable_keys = array_flip(array_diff(form_state_keys_no_cache(), array('always_process', 'temporary')));
+      $form_state = array_diff_key($form_state, $uncacheable_keys);
+      $form_state += $form_state_before_retrieval;
+    }
+  }
+
+  // Now that we have a constructed form, process it. This is where:
+  // - Element #process functions get called to further refine $form.
+  // - User input, if any, gets incorporated in the #value property of the
+  //   corresponding elements and into $form_state['values'].
+  // - Validation and submission handlers are called.
+  // - If this submission is part of a multistep workflow, the form is rebuilt
+  //   to contain the information of the next step.
+  // - If necessary, the form and form state are cached or re-cached, so that
+  //   appropriate information persists to the next page request.
+  // All of the handlers in the pipeline receive $form_state by reference and
+  // can use it to know or update information about the state of the form.
+  drupal_process_form($form_id, $form, $form_state);
+
+  // If this was a successful submission of a single-step form or the last step
+  // of a multi-step form, then drupal_process_form() issued a redirect to
+  // another page, or back to this page, but as a new request. Therefore, if
+  // we're here, it means that this is either a form being viewed initially
+  // before any user input, or there was a validation error requiring the form
+  // to be re-displayed, or we're in a multi-step workflow and need to display
+  // the form's next step. In any case, we have what we need in $form, and can
+  // return it for rendering.
+  return $form;
+}
+
+/**
+ * Retrieves default values for the $form_state array.
+ */
+function form_state_defaults() {
+  return array(
+    'rebuild' => FALSE,
+    'rebuild_info' => array(),
+    'redirect' => NULL,
+    // @todo 'args' is usually set, so no other default 'build_info' keys are
+    //   appended via += form_state_defaults().
+    'build_info' => array(
+      'args' => array(),
+      'files' => array(),
+    ),
+    'temporary' => array(),
+    'submitted' => FALSE,
+    'executed' => FALSE,
+    'programmed' => FALSE,
+    'cache'=> FALSE,
+    'method' => 'post',
+    'groups' => array(),
+    'buttons' => array(),
+  );
+}
+
+/**
+ * Constructs a new $form from the information in $form_state.
+ *
+ * This is the key function for making multi-step forms advance from step to
+ * step. It is called by drupal_process_form() when all user input processing,
+ * including calling validation and submission handlers, for the request is
+ * finished. If a validate or submit handler set $form_state['rebuild'] to TRUE,
+ * and if other conditions don't preempt a rebuild from happening, then this
+ * function is called to generate a new $form, the next step in the form
+ * workflow, to be returned for rendering.
+ *
+ * Ajax form submissions are almost always multi-step workflows, so that is one
+ * common use-case during which form rebuilding occurs. See ajax_form_callback()
+ * for more information about creating Ajax-enabled forms.
+ *
+ * @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() and search_forms().
+ * @param $form_state
+ *   A keyed array containing the current state of the form.
+ * @param $old_form
+ *   (optional) A previously built $form. Used to retain the #build_id and
+ *   #action properties in Ajax callbacks and similar partial form rebuilds. The
+ *   only properties copied from $old_form are the ones which both exist in
+ *   $old_form and for which $form_state['rebuild_info']['copy'][PROPERTY] is
+ *   TRUE. If $old_form is not passed, the entire $form is rebuilt freshly.
+ *   'rebuild_info' needs to be a separate top-level property next to
+ *   'build_info', since the contained data must not be cached.
+ *
+ * @return
+ *   The newly built form.
+ *
+ * @see drupal_process_form()
+ * @see ajax_form_callback()
+ */
+function drupal_rebuild_form($form_id, &$form_state, $old_form = NULL) {
+  $form = drupal_retrieve_form($form_id, $form_state);
+
+  // If only parts of the form will be returned to the browser (e.g., Ajax or
+  // RIA clients), re-use the old #build_id to not require client-side code to
+  // manually update the hidden 'build_id' input element.
+  // Otherwise, a new #build_id is generated, to not clobber the previous
+  // build's data in the form cache; also allowing the user to go back to an
+  // earlier build, make changes, and re-submit.
+  // @see drupal_prepare_form()
+  if (isset($old_form['#build_id']) && !empty($form_state['rebuild_info']['copy']['#build_id'])) {
+    $form['#build_id'] = $old_form['#build_id'];
+  }
+  else {
+    $form['#build_id'] = 'form-' . drupal_hash_base64(uniqid(mt_rand(), TRUE) . mt_rand());
+  }
+
+  // #action defaults to request_uri(), but in case of Ajax and other partial
+  // rebuilds, the form is submitted to an alternate URL, and the original
+  // #action needs to be retained.
+  if (isset($old_form['#action']) && !empty($form_state['rebuild_info']['copy']['#action'])) {
+    $form['#action'] = $old_form['#action'];
+  }
+
+  drupal_prepare_form($form_id, $form, $form_state);
+
+  // Caching is normally done in drupal_process_form(), but what needs to be
+  // cached is the $form structure before it passes through form_builder(),
+  // so we need to do it here.
+  // @todo For Drupal 8, find a way to avoid this code duplication.
+  if (empty($form_state['no_cache'])) {
+    form_set_cache($form['#build_id'], $form, $form_state);
+  }
+
+  // Clear out all group associations as these might be different when
+  // re-rendering the form.
+  $form_state['groups'] = array();
+
+  // Return a fully built form that is ready for rendering.
+  return form_builder($form_id, $form, $form_state);
+}
+
+/**
+ * Fetches a form from cache.
+ */
+function form_get_cache($form_build_id, &$form_state) {
+  if ($cached = cache_get('form_' . $form_build_id, 'cache_form')) {
+    $form = $cached->data;
+
+    global $user;
+    if ((isset($form['#cache_token']) && drupal_valid_token($form['#cache_token'])) || (!isset($form['#cache_token']) && !$user->uid)) {
+      if ($cached = cache_get('form_state_' . $form_build_id, 'cache_form')) {
+        // Re-populate $form_state for subsequent rebuilds.
+        $form_state = $cached->data + $form_state;
+
+        // If the original form is contained in include files, load the files.
+        // @see form_load_include()
+        $form_state['build_info'] += array('files' => array());
+        foreach ($form_state['build_info']['files'] as $file) {
+          if (is_array($file)) {
+            $file += array('type' => 'inc', 'name' => $file['module']);
+            module_load_include($file['type'], $file['module'], $file['name']);
+          }
+          elseif (file_exists($file)) {
+            require_once DRUPAL_ROOT . '/' . $file;
+          }
+        }
+      }
+      return $form;
+    }
+  }
+}
+
+/**
+ * Stores a form in the cache.
+ */
+function form_set_cache($form_build_id, $form, $form_state) {
+  // 6 hours cache life time for forms should be plenty.
+  $expire = 21600;
+
+  // Cache form structure.
+  if (isset($form)) {
+    if ($GLOBALS['user']->uid) {
+      $form['#cache_token'] = drupal_get_token();
+    }
+    cache_set('form_' . $form_build_id, $form, 'cache_form', REQUEST_TIME + $expire);
+  }
+
+  // Cache form state.
+  if ($data = array_diff_key($form_state, array_flip(form_state_keys_no_cache()))) {
+    cache_set('form_state_' . $form_build_id, $data, 'cache_form', REQUEST_TIME + $expire);
+  }
+}
+
+/**
+ * Returns an array of $form_state keys that shouldn't be cached.
+ */
+function form_state_keys_no_cache() {
+  return array(
+    // Public properties defined by form constructors and form handlers.
+    'always_process',
+    'must_validate',
+    'rebuild',
+    'rebuild_info',
+    'redirect',
+    'no_redirect',
+    'temporary',
+    // Internal properties defined by form processing.
+    'buttons',
+    'triggering_element',
+    'clicked_button',
+    'complete form',
+    'groups',
+    'input',
+    'method',
+    'submit_handlers',
+    'submitted',
+    'executed',
+    'validate_handlers',
+    'values',
+  );
+}
+
+/**
+ * Ensures an include file is loaded whenever the form is processed.
+ *
+ * Example:
+ * @code
+ *   // Load node.admin.inc from Node module.
+ *   form_load_include($form_state, 'inc', 'node', 'node.admin');
+ * @endcode
+ *
+ * Use this function instead of module_load_include() from inside a form
+ * constructor or any form processing logic as it ensures that the include file
+ * is loaded whenever the form is processed. In contrast to using
+ * module_load_include() directly, form_load_include() makes sure the include
+ * file is correctly loaded also if the form is cached.
+ *
+ * @param $form_state
+ *   The current state of the form.
+ * @param $type
+ *   The include file's type (file extension).
+ * @param $module
+ *   The module to which the include file belongs.
+ * @param $name
+ *   (optional) The base file name (without the $type extension). If omitted,
+ *   $module is used; i.e., resulting in "$module.$type" by default.
+ *
+ * @return
+ *   The filepath of the loaded include file, or FALSE if the include file was
+ *   not found or has been loaded already.
+ *
+ * @see module_load_include()
+ */
+function form_load_include(&$form_state, $type, $module, $name = NULL) {
+  if (!isset($name)) {
+    $name = $module;
+  }
+  if (!isset($form_state['build_info']['files']["$module:$name.$type"])) {
+    // Only add successfully included files to the form state.
+    if ($result = module_load_include($type, $module, $name)) {
+      $form_state['build_info']['files']["$module:$name.$type"] = array(
+        'type' => $type,
+        'module' => $module,
+        'name' => $name,
+      );
+      return $result;
+    }
+  }
+  return FALSE;
+}
+
+/**
+ * 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().
+ *
+ * @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() and search_forms().
+ * @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. If a key is not
+ *   filled in $form_state['values'], then the default value of the respective
+ *   element is used. To submit an unchecked checkbox or other control that
+ *   browsers submit by not having a $_POST entry, include the key, but set the
+ *   value to NULL.
+ * @param ...
+ *   Any additional arguments are passed on to the functions called by
+ *   drupal_form_submit(), 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. Arguments that need to be passed by reference
+ *   should not be included here, but rather placed directly in the $form_state
+ *   build info array so that the reference can be preserved. For example, a
+ *   form builder function with the following signature:
+ *   @code
+ *   function mymodule_form($form, &$form_state, &$object) {
+ *   }
+ *   @endcode
+ *   would be called via drupal_form_submit() as follows:
+ *   @code
+ *   $form_state['values'] = $my_form_values;
+ *   $form_state['build_info']['args'] = array(&$object);
+ *   drupal_form_submit('mymodule_form', $form_state);
+ *   @endcode
+ * For example:
+ * @code
+ * // register a new user
+ * $form_state = array();
+ * $form_state['values']['name'] = 'robo-user';
+ * $form_state['values']['mail'] = '[e-mail]';
+ * $form_state['values']['pass']['pass1'] = 'password';
+ * $form_state['values']['pass']['pass2'] = 'password';
+ * $form_state['values']['op'] = t('Create new account');
+ * drupal_form_submit('user_register_form', $form_state);
+ * @endcode
+ */
+function drupal_form_submit($form_id, &$form_state) {
+  if (!isset($form_state['build_info']['args'])) {
+    $args = func_get_args();
+    array_shift($args);
+    array_shift($args);
+    $form_state['build_info']['args'] = $args;
+  }
+  // Merge in default values.
+  $form_state += form_state_defaults();
+
+  // Populate $form_state['input'] with the submitted values before retrieving
+  // the form, to be consistent with what drupal_build_form() does for
+  // non-programmatic submissions (form builder functions may expect it to be
+  // there).
+  $form_state['input'] = $form_state['values'];
+
+  $form_state['programmed'] = TRUE;
+  $form = drupal_retrieve_form($form_id, $form_state);
+  // Programmed forms are always submitted.
+  $form_state['submitted'] = TRUE;
+
+  // Reset form validation.
+  $form_state['must_validate'] = TRUE;
+  form_clear_error();
+
+  drupal_prepare_form($form_id, $form, $form_state);
+  drupal_process_form($form_id, $form, $form_state);
+}
+
+/**
+ * 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
+ *   different $form_id values to the proper form constructor function.
+ * @param $form_state
+ *   A keyed array containing the current state of the form, including the
+ *   additional arguments to drupal_get_form() or drupal_form_submit() in the
+ *   'args' component of the array.
+ */
+function drupal_retrieve_form($form_id, &$form_state) {
+  $forms = &drupal_static(__FUNCTION__);
+
+  // Record the $form_id.
+  $form_state['build_info']['form_id'] = $form_id;
+
+  // Record the filepath of the include file containing the original form, so
+  // the form builder callbacks can be loaded when the form is being rebuilt
+  // from cache on a different path (such as 'system/ajax'). See
+  // form_get_cache(). Don't do this in maintenance mode as Drupal may not be
+  // fully bootstrapped (i.e. during installation) in which case
+  // menu_get_item() is not available.
+  if (!isset($form_state['build_info']['files']['menu']) && !defined('MAINTENANCE_MODE')) {
+    $item = menu_get_item();
+    if (!empty($item['include_file'])) {
+      // Do not use form_load_include() here, as the file is already loaded.
+      // Anyway, form_get_cache() is able to handle filepaths too.
+      $form_state['build_info']['files']['menu'] = $item['include_file'];
+    }
+  }
+
+  // We save two copies of the incoming arguments: one for modules to use
+  // when mapping form ids to constructor functions, and another to pass to
+  // the constructor function itself.
+  $args = $form_state['build_info']['args'];
+
+  // We first check to see if there's a function named after the $form_id.
+  // If there is, we simply pass the arguments on to it to get the form.
+  if (!function_exists($form_id)) {
+    // In cases where many form_ids need to share a central constructor function,
+    // such as the node editing form, modules can implement hook_forms(). It
+    // maps one or more form_ids to the correct constructor functions.
+    //
+    // 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])) {
+      $forms = module_invoke_all('forms', $form_id, $args);
+    }
+    $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'];
+      $form_state['build_info']['base_form_id'] = $callback;
+    }
+    // In case $form_state['wrapper_callback'] is not defined already, we also
+    // allow hook_forms() to define one.
+    if (!isset($form_state['wrapper_callback']) && isset($form_definition['wrapper_callback'])) {
+      $form_state['wrapper_callback'] = $form_definition['wrapper_callback'];
+    }
+  }
+
+  $form = array();
+  // We need to pass $form_state by reference in order for forms to modify it,
+  // since call_user_func_array() requires that referenced variables are passed
+  // explicitly.
+  $args = array_merge(array($form, &$form_state), $args);
+
+  // When the passed $form_state (not using drupal_get_form()) defines a
+  // 'wrapper_callback', then it requests to invoke a separate (wrapping) form
+  // builder function to pre-populate the $form array with form elements, which
+  // the actual form builder function ($callback) expects. This allows for
+  // pre-populating a form with common elements for certain forms, such as
+  // back/next/save buttons in multi-step form wizards. See drupal_build_form().
+  if (isset($form_state['wrapper_callback']) && function_exists($form_state['wrapper_callback'])) {
+    $form = call_user_func_array($form_state['wrapper_callback'], $args);
+    // Put the prepopulated $form into $args.
+    $args[0] = $form;
+  }
+
+  // If $callback was returned by a hook_forms() implementation, call it.
+  // Otherwise, call the function named after the form id.
+  $form = call_user_func_array(isset($callback) ? $callback : $form_id, $args);
+  $form['#form_id'] = $form_id;
+
+  return $form;
+}
+
+/**
+ * Processes a form submission.
+ *
+ * This function is the heart of form API. The form gets built, validated and in
+ * appropriate cases, submitted and rebuilt.
+ *
+ * @param $form_id
+ *   The unique string identifying the current form.
+ * @param $form
+ *   An associative array containing the structure of the form.
+ * @param $form_state
+ *   A keyed array containing the current state of the form. This
+ *   includes the current persistent storage data for the form, and
+ *   any data passed along by earlier steps when displaying a
+ *   multi-step form. Additional information, like the sanitized $_POST
+ *   data, is also accumulated here.
+ */
+function drupal_process_form($form_id, &$form, &$form_state) {
+  $form_state['values'] = array();
+
+  // 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']);
+    }
+  }
+
+  // form_builder() finishes building the form by calling element #process
+  // functions and mapping user input, if any, to #value properties, and also
+  // storing the values in $form_state['values']. We need to retain the
+  // unprocessed $form in case it needs to be cached.
+  $unprocessed_form = $form;
+  $form = form_builder($form_id, $form, $form_state);
+
+  // Only process the input if we have a correct form submission.
+  if ($form_state['process_input']) {
+    drupal_validate_form($form_id, $form, $form_state);
+
+    // drupal_html_id() maintains a cache of element IDs it has seen,
+    // so it can prevent duplicates. We want to be sure we reset that
+    // cache when a form is processed, so scenarios that result in
+    // the form being built behind the scenes and again for the
+    // browser don't increment all the element IDs needlessly.
+    if (!form_get_errors()) {
+      // In case of errors, do not break HTML IDs of other forms.
+      drupal_static_reset('drupal_html_id');
+    }
+
+    if ($form_state['submitted'] && !form_get_errors() && !$form_state['rebuild']) {
+      // Execute form submit handlers.
+      form_execute_handlers('submit', $form, $form_state);
+
+      // We'll clear out the cached copies of the form and its stored data
+      // here, as we've finished with them. The in-memory copies are still
+      // here, though.
+      if (!variable_get('cache', 0) && !empty($form_state['values']['form_build_id'])) {
+        cache_clear_all('form_' . $form_state['values']['form_build_id'], 'cache_form');
+        cache_clear_all('form_state_' . $form_state['values']['form_build_id'], 'cache_form');
+      }
+
+      // If batches were set in the submit handlers, we process them now,
+      // possibly ending execution. We make sure we do not react to the batch
+      // that is already being processed (if a batch operation performs a
+      // drupal_form_submit).
+      if ($batch =& batch_get() && !isset($batch['current_set'])) {
+        // Store $form_state information in the batch definition.
+        // We need the full $form_state when either:
+        // - Some submit handlers were saved to be called during batch
+        //   processing. See form_execute_handlers().
+        // - The form is multistep.
+        // In other cases, we only need the information expected by
+        // drupal_redirect_form().
+        if ($batch['has_form_submits'] || !empty($form_state['rebuild'])) {
+          $batch['form_state'] = $form_state;
+        }
+        else {
+          $batch['form_state'] = array_intersect_key($form_state, array_flip(array('programmed', 'rebuild', 'storage', 'no_redirect', 'redirect')));
+        }
+
+        $batch['progressive'] = !$form_state['programmed'];
+        batch_process();
+
+        // 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.
+      }
+
+      // Set a flag to indicate the the form has been processed and executed.
+      $form_state['executed'] = TRUE;
+
+      // Redirect the form based on values in $form_state.
+      drupal_redirect_form($form_state);
+    }
+
+    // Don't rebuild or cache form submissions invoked via drupal_form_submit().
+    if (!empty($form_state['programmed'])) {
+      return;
+    }
+
+    // If $form_state['rebuild'] has been set and input has been processed
+    // without validation errors, we are in a multi-step workflow that is not
+    // yet complete. A new $form needs to be constructed based on the changes
+    // made to $form_state during this request. Normally, a submit handler sets
+    // $form_state['rebuild'] if a fully executed form requires another step.
+    // However, for forms that have not been fully executed (e.g., Ajax
+    // submissions triggered by non-buttons), there is no submit handler to set
+    // $form_state['rebuild']. It would not make sense to redisplay the
+    // identical form without an error for the user to correct, so we also
+    // rebuild error-free non-executed forms, regardless of
+    // $form_state['rebuild'].
+    // @todo D8: Simplify this logic; considering Ajax and non-HTML front-ends,
+    //   along with element-level #submit properties, it makes no sense to have
+    //   divergent form execution based on whether the triggering element has
+    //   #executes_submit_callback set to TRUE.
+    if (($form_state['rebuild'] || !$form_state['executed']) && !form_get_errors()) {
+      // Form building functions (e.g., _form_builder_handle_input_element())
+      // may use $form_state['rebuild'] to determine if they are running in the
+      // context of a rebuild, so ensure it is set.
+      $form_state['rebuild'] = TRUE;
+      $form = drupal_rebuild_form($form_id, $form_state, $form);
+    }
+  }
+
+  // After processing the form, the form builder or a #process callback may
+  // have set $form_state['cache'] to indicate that the form and form state
+  // shall be cached. But the form may only be cached if the 'no_cache' property
+  // is not set to TRUE. Only cache $form as it was prior to form_builder(),
+  // because form_builder() must run for each request to accommodate new user
+  // input. Rebuilt forms are not cached here, because drupal_rebuild_form()
+  // already takes care of that.
+  if (!$form_state['rebuild'] && $form_state['cache'] && empty($form_state['no_cache'])) {
+    form_set_cache($form['#build_id'], $unprocessed_form, $form_state);
+  }
+}
+
+/**
+ * Prepares a structured form array.
+ *
+ * Adds required elements, executes any hook_form_alter functions, and
+ * optionally inserts 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.
+ * @param $form_state
+ *   A keyed array containing the current state of the form. Passed
+ *   in here so that hook_form_alter() calls can use it, as well.
+ */
+function drupal_prepare_form($form_id, &$form, &$form_state) {
+  global $user;
+
+  $form['#type'] = 'form';
+  $form_state['programmed'] = isset($form_state['programmed']) ? $form_state['programmed'] : FALSE;
+
+  // Fix the form method, if it is 'get' in $form_state, but not in $form.
+  if ($form_state['method'] == 'get' && !isset($form['#method'])) {
+    $form['#method'] = 'get';
+  }
+
+  // Generate a new #build_id for this form, if none has been set already. The
+  // form_build_id is used as key to cache a particular build of the form. For
+  // multi-step forms, this allows the user to go back to an earlier build, make
+  // changes, and re-submit.
+  // @see drupal_build_form()
+  // @see drupal_rebuild_form()
+  if (!isset($form['#build_id'])) {
+    $form['#build_id'] = 'form-' . drupal_hash_base64(uniqid(mt_rand(), TRUE) . mt_rand());
+  }
+  $form['form_build_id'] = array(
+    '#type' => 'hidden',
+    '#value' => $form['#build_id'],
+    '#id' => $form['#build_id'],
+    '#name' => 'form_build_id',
+    // Form processing and validation requires this value, so ensure the
+    // submitted form value appears literally, regardless of custom #tree
+    // and #parents being set elsewhere.
+    '#parents' => array('form_build_id'),
+  );
+
+  // 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.
+  // This does not apply to programmatically submitted forms. Furthermore, since
+  // tokens are session-bound and forms displayed to anonymous users are very
+  // likely cached, we cannot assign a token for them.
+  // During installation, there is no $user yet.
+  if (!empty($user->uid) && !$form_state['programmed']) {
+    // Form constructors may explicitly set #token to FALSE when cross site
+    // request forgery is irrelevant to the form, such as search forms.
+    if (isset($form['#token']) && $form['#token'] === FALSE) {
+      unset($form['#token']);
+    }
+    // Otherwise, generate a public token based on the form id.
+    else {
+      $form['#token'] = $form_id;
+      $form['form_token'] = array(
+        '#id' => drupal_html_id('edit-' . $form_id . '-form-token'),
+        '#type' => 'token',
+        '#default_value' => drupal_get_token($form['#token']),
+        // Form processing and validation requires this value, so ensure the
+        // submitted form value appears literally, regardless of custom #tree
+        // and #parents being set elsewhere.
+        '#parents' => array('form_token'),
+      );
+    }
+  }
+
+  if (isset($form_id)) {
+    $form['form_id'] = array(
+      '#type' => 'hidden',
+      '#value' => $form_id,
+      '#id' => drupal_html_id("edit-$form_id"),
+      // Form processing and validation requires this value, so ensure the
+      // submitted form value appears literally, regardless of custom #tree
+      // and #parents being set elsewhere.
+      '#parents' => array('form_id'),
+    );
+  }
+  if (!isset($form['#id'])) {
+    $form['#id'] = drupal_html_id($form_id);
+  }
+
+  $form += element_info('form');
+  $form += array('#tree' => FALSE, '#parents' => array());
+
+  if (!isset($form['#validate'])) {
+    // Ensure that modules can rely on #validate being set.
+    $form['#validate'] = array();
+    // Check for a handler specific to $form_id.
+    if (function_exists($form_id . '_validate')) {
+      $form['#validate'][] = $form_id . '_validate';
+    }
+    // Otherwise check whether this is a shared form and whether there is a
+    // handler for the shared $form_id.
+    elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_validate')) {
+      $form['#validate'][] = $form_state['build_info']['base_form_id'] . '_validate';
+    }
+  }
+
+  if (!isset($form['#submit'])) {
+    // Ensure that modules can rely on #submit being set.
+    $form['#submit'] = array();
+    // Check for a handler specific to $form_id.
+    if (function_exists($form_id . '_submit')) {
+      $form['#submit'][] = $form_id . '_submit';
+    }
+    // Otherwise check whether this is a shared form and whether there is a
+    // handler for the shared $form_id.
+    elseif (isset($form_state['build_info']['base_form_id']) && function_exists($form_state['build_info']['base_form_id'] . '_submit')) {
+      $form['#submit'][] = $form_state['build_info']['base_form_id'] . '_submit';
+    }
+  }
+
+  // If no #theme has been set, automatically apply theme suggestions.
+  // theme_form() itself is in #theme_wrappers and not #theme. Therefore, the
+  // #theme function only has to care for rendering the inner form elements,
+  // not the form itself.
+  if (!isset($form['#theme'])) {
+    $form['#theme'] = array($form_id);
+    if (isset($form_state['build_info']['base_form_id'])) {
+      $form['#theme'][] = $form_state['build_info']['base_form_id'];
+    }
+  }
+
+  // Invoke hook_form_alter(), hook_form_BASE_FORM_ID_alter(), and
+  // hook_form_FORM_ID_alter() implementations.
+  $hooks = array('form');
+  if (isset($form_state['build_info']['base_form_id'])) {
+    $hooks[] = 'form_' . $form_state['build_info']['base_form_id'];
+  }
+  $hooks[] = 'form_' . $form_id;
+  drupal_alter($hooks, $form, $form_state, $form_id);
+}
+
+
+/**
+ * Validates user-submitted form data in the $form_state 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, which is passed
+ *   by reference. Form validation handlers are able to alter the form structure
+ *   (like #process and #after_build callbacks during form building) in case of
+ *   a validation error. If a validation handler alters the form structure, it
+ *   is responsible for validating the values of changed form elements in
+ *   $form_state['values'] to prevent form submit handlers from receiving
+ *   unvalidated values.
+ * @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 use
+ *   $form_state to pass information on to submit handlers. For example:
+ *     $form_state['data_for_submission'] = $data;
+ *   This technique is useful when validation requires file parsing,
+ *   web service requests, or other expensive requests that should
+ *   not be repeated in the submission step.
+ */
+function drupal_validate_form($form_id, &$form, &$form_state) {
+  $validated_forms = &drupal_static(__FUNCTION__, array());
+
+  if (isset($validated_forms[$form_id]) && empty($form_state['must_validate'])) {
+    return;
+  }
+
+  // If the session token was set by drupal_prepare_form(), ensure that it
+  // matches the current user's session.
+  if (isset($form['#token'])) {
+    if (!drupal_valid_token($form_state['values']['form_token'], $form['#token'])) {
+      $path = current_path();
+      $query = drupal_get_query_parameters();
+      $url = url($path, array('query' => $query));
+
+      // Setting this error will cause the form to fail validation.
+      form_set_error('form_token', t('The form has become outdated. Copy any unsaved work in the form below and then <a href="@link">reload this page</a>.', array('@link' => $url)));
+    }
+  }
+
+  _form_validate($form, $form_state, $form_id);
+  $validated_forms[$form_id] = TRUE;
+
+  // If validation errors are limited then remove any non validated form values,
+  // so that only values that passed validation are left for submit callbacks.
+  if (isset($form_state['triggering_element']['#limit_validation_errors']) && $form_state['triggering_element']['#limit_validation_errors'] !== FALSE) {
+    $values = array();
+    foreach ($form_state['triggering_element']['#limit_validation_errors'] as $section) {
+      // If the section exists within $form_state['values'], even if the value
+      // is NULL, copy it to $values.
+      $section_exists = NULL;
+      $value = drupal_array_get_nested_value($form_state['values'], $section, $section_exists);
+      if ($section_exists) {
+        drupal_array_set_nested_value($values, $section, $value);
+      }
+    }
+    // A button's #value does not require validation, so for convenience we
+    // allow the value of the clicked button to be retained in its normal
+    // $form_state['values'] locations, even if these locations are not included
+    // in #limit_validation_errors.
+    if (isset($form_state['triggering_element']['#button_type'])) {
+      $button_value = $form_state['triggering_element']['#value'];
+
+      // Like all input controls, the button value may be in the location
+      // dictated by #parents. If it is, copy it to $values, but do not override
+      // what may already be in $values.
+      $parents = $form_state['triggering_element']['#parents'];
+      if (!drupal_array_nested_key_exists($values, $parents) && drupal_array_get_nested_value($form_state['values'], $parents) === $button_value) {
+        drupal_array_set_nested_value($values, $parents, $button_value);
+      }
+
+      // Additionally, form_builder() places the button value in
+      // $form_state['values'][BUTTON_NAME]. If it's still there, after
+      // validation handlers have run, copy it to $values, but do not override
+      // what may already be in $values.
+      $name = $form_state['triggering_element']['#name'];
+      if (!isset($values[$name]) && isset($form_state['values'][$name]) && $form_state['values'][$name] === $button_value) {
+        $values[$name] = $button_value;
+      }
+    }
+    $form_state['values'] = $values;
+  }
+}
+
+/**
+ * Redirects the user to a URL after a form has been processed.
+ *
+ * After a form is submitted and processed, normally the user should be
+ * redirected to a new destination page. This function figures out what that
+ * destination should be, based on the $form_state array and the 'destination'
+ * query string in the request URL, and redirects the user there.
+ *
+ * Usually (for exceptions, see below) $form_state['redirect'] determines where
+ * to redirect the user. This can be set either to a string (the path to
+ * redirect to), or an array of arguments for drupal_goto(). If
+ * $form_state['redirect'] is missing, the user is usually (again, see below for
+ * exceptions) redirected back to the page they came from, where they should see
+ * a fresh, unpopulated copy of the form.
+ *
+ * Here is an example of how to set up a form to redirect to the path 'node':
+ * @code
+ * $form_state['redirect'] = 'node';
+ * @endcode
+ * And here is an example of how to redirect to 'node/123?foo=bar#baz':
+ * @code
+ * $form_state['redirect'] = array(
+ *   'node/123',
+ *   array(
+ *     'query' => array(
+ *       'foo' => 'bar',
+ *     ),
+ *     'fragment' => 'baz',
+ *   ),
+ * );
+ * @endcode
+ *
+ * There are several exceptions to the "usual" behavior described above:
+ * - If $form_state['programmed'] is TRUE, the form submission was usually
+ *   invoked via drupal_form_submit(), so any redirection would break the script
+ *   that invoked drupal_form_submit() and no redirection is done.
+ * - If $form_state['rebuild'] is TRUE, the form is being rebuilt, and no
+ *   redirection is done.
+ * - If $form_state['no_redirect'] is TRUE, redirection is disabled. This is
+ *   set, for instance, by ajax_get_form() to prevent redirection in Ajax
+ *   callbacks. $form_state['no_redirect'] should never be set or altered by
+ *   form builder functions or form validation/submit handlers.
+ * - If $form_state['redirect'] is set to FALSE, redirection is disabled.
+ * - If none of the above conditions has prevented redirection, then the
+ *   redirect is accomplished by calling drupal_goto(), passing in the value of
+ *   $form_state['redirect'] if it is set, or the current path if it is
+ *   not. drupal_goto() preferentially uses the value of $_GET['destination']
+ *   (the 'destination' URL query string) if it is present, so this will
+ *   override any values set by $form_state['redirect']. Note that during
+ *   installation, install_goto() is called in place of drupal_goto().
+ *
+ * @param $form_state
+ *   An associative array containing the current state of the form.
+ *
+ * @see drupal_process_form()
+ * @see drupal_build_form()
+ */
+function drupal_redirect_form($form_state) {
+  // Skip redirection for form submissions invoked via drupal_form_submit().
+  if (!empty($form_state['programmed'])) {
+    return;
+  }
+  // Skip redirection if rebuild is activated.
+  if (!empty($form_state['rebuild'])) {
+    return;
+  }
+  // Skip redirection if it was explicitly disallowed.
+  if (!empty($form_state['no_redirect'])) {
+    return;
+  }
+  // Only invoke drupal_goto() if redirect value was not set to FALSE.
+  if (!isset($form_state['redirect']) || $form_state['redirect'] !== FALSE) {
+    if (isset($form_state['redirect'])) {
+      if (is_array($form_state['redirect'])) {
+        call_user_func_array('drupal_goto', $form_state['redirect']);
+      }
+      else {
+        // This function can be called from the installer, which guarantees
+        // that $redirect will always be a string, so catch that case here
+        // and use the appropriate redirect function.
+        $function = drupal_installation_attempted() ? 'install_goto' : 'drupal_goto';
+        $function($form_state['redirect']);
+      }
+    }
+    drupal_goto(current_path(), array('query' => drupal_get_query_parameters()));
+  }
+}
+
+/**
+ * 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.
+ * @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_submission'] = $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.
+ * @param $form_id
+ *   A unique string identifying the form for validation, submission,
+ *   theming, and hook_form_alter functions.
+ */
+function _form_validate(&$elements, &$form_state, $form_id = NULL) {
+  // Also used in the installer, pre-database setup.
+  $t = get_t();
+
+  // Recurse through all children.
+  foreach (element_children($elements) as $key) {
+    if (isset($elements[$key]) && $elements[$key]) {
+      _form_validate($elements[$key], $form_state);
+    }
+  }
+
+  // Validate the current input.
+  if (!isset($elements['#validated']) || !$elements['#validated']) {
+    // The following errors are always shown.
+    if (isset($elements['#needs_validation'])) {
+      // Verify that the value is not longer than #maxlength.
+      if (isset($elements['#maxlength']) && drupal_strlen($elements['#value']) > $elements['#maxlength']) {
+        form_error($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']))));
+      }
+
+      if (isset($elements['#options']) && isset($elements['#value'])) {
+        if ($elements['#type'] == 'select') {
+          $options = form_options_flatten($elements['#options']);
+        }
+        else {
+          $options = $elements['#options'];
+        }
+        if (is_array($elements['#value'])) {
+          $value = in_array($elements['#type'], array('checkboxes', 'tableselect')) ? array_keys($elements['#value']) : $elements['#value'];
+          foreach ($value as $v) {
+            if (!isset($options[$v])) {
+              form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
+              watchdog('form', 'Illegal choice %choice in !name element.', array('%choice' => $v, '!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
+            }
+          }
+        }
+        // Non-multiple select fields always have a value in HTML. If the user
+        // does not change the form, it will be the value of the first option.
+        // Because of this, form validation for the field will almost always
+        // pass, even if the user did not select anything. To work around this
+        // browser behavior, required select fields without a #default_value get
+        // an additional, first empty option. In case the submitted value is
+        // identical to the empty option's value, we reset the element's value
+        // to NULL to trigger the regular #required handling below.
+        // @see form_process_select()
+        elseif ($elements['#type'] == 'select' && !$elements['#multiple'] && $elements['#required'] && !isset($elements['#default_value']) && $elements['#value'] === $elements['#empty_value']) {
+          $elements['#value'] = NULL;
+          form_set_value($elements, NULL, $form_state);
+        }
+        elseif (!isset($options[$elements['#value']])) {
+          form_error($elements, $t('An illegal choice has been detected. Please contact the site administrator.'));
+          watchdog('form', 'Illegal choice %choice in %name element.', array('%choice' => $elements['#value'], '%name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
+        }
+      }
+    }
+
+    // While this element is being validated, it may be desired that some calls
+    // to form_set_error() be suppressed and not result in a form error, so
+    // that a button that implements low-risk functionality (such as "Previous"
+    // or "Add more") that doesn't require all user input to be valid can still
+    // have its submit handlers triggered. The triggering element's
+    // #limit_validation_errors property contains the information for which
+    // errors are needed, and all other errors are to be suppressed. The
+    // #limit_validation_errors property is ignored if submit handlers will run,
+    // but the element doesn't have a #submit property, because it's too large a
+    // security risk to have any invalid user input when executing form-level
+    // submit handlers.
+    if (isset($form_state['triggering_element']['#limit_validation_errors']) && ($form_state['triggering_element']['#limit_validation_errors'] !== FALSE) && !($form_state['submitted'] && !isset($form_state['triggering_element']['#submit']))) {
+      form_set_error(NULL, '', $form_state['triggering_element']['#limit_validation_errors']);
+    }
+    // If submit handlers won't run (due to the submission having been triggered
+    // by an element whose #executes_submit_callback property isn't TRUE), then
+    // it's safe to suppress all validation errors, and we do so by default,
+    // which is particularly useful during an Ajax submission triggered by a
+    // non-button. An element can override this default by setting the
+    // #limit_validation_errors property. For button element types,
+    // #limit_validation_errors defaults to FALSE (via system_element_info()),
+    // so that full validation is their default behavior.
+    elseif (isset($form_state['triggering_element']) && !isset($form_state['triggering_element']['#limit_validation_errors']) && !$form_state['submitted']) {
+      form_set_error(NULL, '', array());
+    }
+    // As an extra security measure, explicitly turn off error suppression if
+    // one of the above conditions wasn't met. Since this is also done at the
+    // end of this function, doing it here is only to handle the rare edge case
+    // where a validate handler invokes form processing of another form.
+    else {
+      drupal_static_reset('form_set_error:limit_validation_errors');
+    }
+
+    // Make sure a value is passed when the field is required.
+    if (isset($elements['#needs_validation']) && $elements['#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.
+      // An unchecked checkbox has a #value of integer 0, different than string
+      // '0', which could be a valid value.
+      $is_empty_multiple = (!count($elements['#value']));
+      $is_empty_string = (is_string($elements['#value']) && drupal_strlen(trim($elements['#value'])) == 0);
+      $is_empty_value = ($elements['#value'] === 0);
+      if ($is_empty_multiple || $is_empty_string || $is_empty_value) {
+        // Although discouraged, a #title is not mandatory for form elements. In
+        // case there is no #title, we cannot set a form error message.
+        // Instead of setting no #title, form constructors are encouraged to set
+        // #title_display to 'invisible' to improve accessibility.
+        if (isset($elements['#title'])) {
+          form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
+        }
+        else {
+          form_error($elements);
+        }
+      }
+    }
+
+    // Call user-defined form level validators.
+    if (isset($form_id)) {
+      form_execute_handlers('validate', $elements, $form_state);
+    }
+    // Call any element-specific validators. These must act on the element
+    // #value data.
+    elseif (isset($elements['#element_validate'])) {
+      foreach ($elements['#element_validate'] as $function) {
+        $function($elements, $form_state, $form_state['complete form']);
+      }
+    }
+    $elements['#validated'] = TRUE;
+  }
+
+  // Done validating this element, so turn off error suppression.
+  // _form_validate() turns it on again when starting on the next element, if
+  // it's still appropriate to do so.
+  drupal_static_reset('form_set_error:limit_validation_errors');
+}
+
+/**
+ * Executes 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) {
+  $return = FALSE;
+  // If there was a button pressed, use its handlers.
+  if (isset($form_state[$type . '_handlers'])) {
+    $handlers = $form_state[$type . '_handlers'];
+  }
+  // Otherwise, check for a form-level handler.
+  elseif (isset($form['#' . $type])) {
+    $handlers = $form['#' . $type];
+  }
+  else {
+    $handlers = array();
+  }
+
+  foreach ($handlers as $function) {
+    // Check if a previous _submit handler has set a batch, but make sure we
+    // do not react to a batch that is already being processed (for instance
+    // if a batch operation performs a drupal_form_submit()).
+    if ($type == 'submit' && ($batch =& batch_get()) && !isset($batch['id'])) {
+      // Some previous submit handler has set a batch. To ensure correct
+      // execution order, store the call in a special 'control' batch set.
+      // See _batch_next_set().
+      $batch['sets'][] = array('form_submit' => $function);
+      $batch['has_form_submits'] = TRUE;
+    }
+    else {
+      $function($form, $form_state);
+    }
+    $return = TRUE;
+  }
+  return $return;
+}
+
+/**
+ * Files an error against a form element.
+ *
+ * When a validation error is detected, the validator calls form_set_error() to
+ * indicate which element needs to be changed and provide an error message. This
+ * causes the Form API to not execute the form submit handlers, and instead to
+ * re-display the form to the user with the corresponding elements rendered with
+ * an 'error' CSS class (shown as red by default).
+ *
+ * The standard form_set_error() behavior can be changed if a button provides
+ * the #limit_validation_errors property. Multistep forms not wanting to
+ * validate the whole form can set #limit_validation_errors on buttons to
+ * limit validation errors to only certain elements. For example, pressing the
+ * "Previous" button in a multistep form should not fire validation errors just
+ * because the current step has invalid values. If #limit_validation_errors is
+ * set on a clicked button, the button must also define a #submit property
+ * (may be set to an empty array). Any #submit handlers will be executed even if
+ * there is invalid input, so extreme care should be taken with respect to any
+ * actions taken by them. This is typically not a problem with buttons like
+ * "Previous" or "Add more" that do not invoke persistent storage of the
+ * submitted form values. Do not use the #limit_validation_errors property on
+ * buttons that trigger saving of form values to the database.
+ *
+ * The #limit_validation_errors property is a list of "sections" within
+ * $form_state['values'] that must contain valid values. Each "section" is an
+ * array with the ordered set of keys needed to reach that part of
+ * $form_state['values'] (i.e., the #parents property of the element).
+ *
+ * Example 1: Allow the "Previous" button to function, regardless of whether any
+ * user input is valid.
+ *
+ * @code
+ *   $form['actions']['previous'] = array(
+ *     '#type' => 'submit',
+ *     '#value' => t('Previous'),
+ *     '#limit_validation_errors' => array(),       // No validation.
+ *     '#submit' => array('some_submit_function'),  // #submit required.
+ *   );
+ * @endcode
+ *
+ * Example 2: Require some, but not all, user input to be valid to process the
+ * submission of a "Previous" button.
+ *
+ * @code
+ *   $form['actions']['previous'] = array(
+ *     '#type' => 'submit',
+ *     '#value' => t('Previous'),
+ *     '#limit_validation_errors' => array(
+ *       array('step1'),       // Validate $form_state['values']['step1'].
+ *       array('foo', 'bar'),  // Validate $form_state['values']['foo']['bar'].
+ *     ),
+ *     '#submit' => array('some_submit_function'), // #submit required.
+ *   );
+ * @endcode
+ *
+ * This will require $form_state['values']['step1'] and everything within it
+ * (for example, $form_state['values']['step1']['choice']) to be valid, so
+ * calls to form_set_error('step1', $message) or
+ * form_set_error('step1][choice', $message) will prevent the submit handlers
+ * from running, and result in the error message being displayed to the user.
+ * However, calls to form_set_error('step2', $message) and
+ * form_set_error('step2][groupX][choiceY', $message) will be suppressed,
+ * resulting in the message not being displayed to the user, and the submit
+ * handlers will run despite $form_state['values']['step2'] and
+ * $form_state['values']['step2']['groupX']['choiceY'] containing invalid
+ * values. Errors for an invalid $form_state['values']['foo'] will be
+ * suppressed, but errors flagging invalid values for
+ * $form_state['values']['foo']['bar'] and everything within it will be
+ * flagged and submission prevented.
+ *
+ * Partial form validation is implemented by suppressing errors rather than by
+ * skipping the input processing and validation steps entirely, because some
+ * forms have button-level submit handlers that call Drupal API functions that
+ * assume that certain data exists within $form_state['values'], and while not
+ * doing anything with that data that requires it to be valid, PHP errors
+ * would be triggered if the input processing and validation steps were fully
+ * skipped.
+ *
+ * @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.
+ * @param $limit_validation_errors
+ *   Internal use only. The #limit_validation_errors property of the clicked
+ *   button, if it exists.
+ *
+ * @return
+ *   Return value is for internal use only. To get a list of errors, use
+ *   form_get_errors() or form_get_error().
+ *
+ * @see http://drupal.org/node/370537
+ * @see http://drupal.org/node/763376
+ */
+function form_set_error($name = NULL, $message = '', $limit_validation_errors = NULL) {
+  $form = &drupal_static(__FUNCTION__, array());
+  $sections = &drupal_static(__FUNCTION__ . ':limit_validation_errors');
+  if (isset($limit_validation_errors)) {
+    $sections = $limit_validation_errors;
+  }
+
+  if (isset($name) && !isset($form[$name])) {
+    $record = TRUE;
+    if (isset($sections)) {
+      // #limit_validation_errors is an array of "sections" within which user
+      // input must be valid. If the element is within one of these sections,
+      // the error must be recorded. Otherwise, it can be suppressed.
+      // #limit_validation_errors can be an empty array, in which case all
+      // errors are suppressed. For example, a "Previous" button might want its
+      // submit action to be triggered even if none of the submitted values are
+      // valid.
+      $record = FALSE;
+      foreach ($sections as $section) {
+        // Exploding by '][' reconstructs the element's #parents. If the
+        // reconstructed #parents begin with the same keys as the specified
+        // section, then the element's values are within the part of
+        // $form_state['values'] that the clicked button requires to be valid,
+        // so errors for this element must be recorded. As the exploded array
+        // will all be strings, we need to cast every value of the section
+        // array to string.
+        if (array_slice(explode('][', $name), 0, count($section)) === array_map('strval', $section)) {
+          $record = TRUE;
+          break;
+        }
+      }
+    }
+    if ($record) {
+      $form[$name] = $message;
+      if ($message) {
+        drupal_set_message($message, 'error');
+      }
+    }
+  }
+
+  return $form;
+}
+
+/**
+ * Clears all errors against all form elements made by form_set_error().
+ */
+function form_clear_error() {
+  drupal_static_reset('form_set_error');
+}
+
+/**
+ * Returns an associative array of all errors.
+ */
+function form_get_errors() {
+  $form = form_set_error();
+  if (!empty($form)) {
+    return $form;
+  }
+}
+
+/**
+ * Returns the error message filed against the given form element.
+ *
+ * Form errors higher up in the form structure override deeper errors as well as
+ * errors on the element itself.
+ */
+function form_get_error($element) {
+  $form = form_set_error();
+  $parents = array();
+  foreach ($element['#parents'] as $parent) {
+    $parents[] = $parent;
+    $key = implode('][', $parents);
+    if (isset($form[$key])) {
+      return $form[$key];
+    }
+  }
+}
+
+/**
+ * Flags an element as having an error.
+ */
+function form_error(&$element, $message = '') {
+  form_set_error(implode('][', $element['#parents']), $message);
+}
+
+/**
+ * Builds and processes all elements in the structured form array.
+ *
+ * Adds any required properties to each element, maps the incoming input data
+ * to the proper elements, and executes any #process handlers attached to a
+ * specific element.
+ *
+ * This is one of the three primary functions that recursively iterates a form
+ * array. This one does it for completing the form building process. The other
+ * two are _form_validate() (invoked via drupal_validate_form() and used to
+ * invoke validation logic for each element) and drupal_render() (for rendering
+ * each element). Each of these three pipelines provides ample opportunity for
+ * modules to customize what happens. For example, during this function's life
+ * cycle, the following functions get called for each element:
+ * - $element['#value_callback']: A function that implements how user input is
+ *   mapped to an element's #value property. This defaults to a function named
+ *   'form_type_TYPE_value' where TYPE is $element['#type'].
+ * - $element['#process']: An array of functions called after user input has
+ *   been mapped to the element's #value property. These functions can be used
+ *   to dynamically add child elements: for example, for the 'date' element
+ *   type, one of the functions in this array is form_process_date(), which adds
+ *   the individual 'year', 'month', 'day', etc. child elements. These functions
+ *   can also be used to set additional properties or implement special logic
+ *   other than adding child elements: for example, for the 'fieldset' element
+ *   type, one of the functions in this array is form_process_fieldset(), which
+ *   adds the attributes and JavaScript needed to make the fieldset collapsible
+ *   if the #collapsible property is set. The #process functions are called in
+ *   preorder traversal, meaning they are called for the parent element first,
+ *   then for the child elements.
+ * - $element['#after_build']: An array of functions called after form_builder()
+ *   is done with its processing of the element. These are called in postorder
+ *   traversal, meaning they are called for the child elements first, then for
+ *   the parent element.
+ * There are similar properties containing callback functions invoked by
+ * _form_validate() and drupal_render(), appropriate for those operations.
+ *
+ * Developers are strongly encouraged to integrate the functionality needed by
+ * their form or module within one of these three pipelines, using the
+ * appropriate callback property, rather than implementing their own recursive
+ * traversal of a form array. This facilitates proper integration between
+ * multiple modules. For example, module developers are familiar with the
+ * relative order in which hook_form_alter() implementations and #process
+ * functions run. A custom traversal function that affects the building of a
+ * form is likely to not integrate with hook_form_alter() and #process in the
+ * expected way. Also, deep recursion within PHP is both slow and memory
+ * intensive, so it is best to minimize how often it's done.
+ *
+ * As stated above, each element's #process functions are executed after its
+ * #value has been set. This enables those functions to execute conditional
+ * logic based on the current value. However, all of form_builder() runs before
+ * drupal_validate_form() is called, so during #process function execution, the
+ * element's #value has not yet been validated, so any code that requires
+ * validated values must reside within a submit handler.
+ *
+ * As a security measure, user input is used for an element's #value only if the
+ * element exists within $form, is not disabled (as per the #disabled property),
+ * and can be accessed (as per the #access property, except that forms submitted
+ * using drupal_form_submit() bypass #access restrictions). When user input is
+ * ignored due to #disabled and #access restrictions, the element's default
+ * value is used.
+ *
+ * Because of the preorder traversal, where #process functions of an element run
+ * before user input for its child elements is processed, and because of the
+ * Form API security of user input processing with respect to #access and
+ * #disabled described above, this generally means that #process functions
+ * should not use an element's (unvalidated) #value to affect the #disabled or
+ * #access of child elements. Use-cases where a developer may be tempted to
+ * implement such conditional logic usually fall into one of two categories:
+ * - Where user input from the current submission must affect the structure of a
+ *   form, including properties like #access and #disabled that affect how the
+ *   next submission needs to be processed, a multi-step workflow is needed.
+ *   This is most commonly implemented with a submit handler setting persistent
+ *   data within $form_state based on *validated* values in
+ *   $form_state['values'] and setting $form_state['rebuild']. The form building
+ *   functions must then be implemented to use the $form_state data to rebuild
+ *   the form with the structure appropriate for the new state.
+ * - Where user input must affect the rendering of the form without affecting
+ *   its structure, the necessary conditional rendering logic should reside
+ *   within functions that run during the rendering phase (#pre_render, #theme,
+ *   #theme_wrappers, and #post_render).
+ *
+ * @param $form_id
+ *   A unique string identifying the form for validation, submission,
+ *   theming, and hook_form_alter functions.
+ * @param $element
+ *   An associative array containing the structure of the current element.
+ * @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
+ *   $_POST data.
+ */
+function form_builder($form_id, &$element, &$form_state) {
+  // Initialize as unprocessed.
+  $element['#processed'] = FALSE;
+
+  // Use element defaults.
+  if (isset($element['#type']) && empty($element['#defaults_loaded']) && ($info = element_info($element['#type']))) {
+    // Overlay $info onto $element, retaining preexisting keys in $element.
+    $element += $info;
+    $element['#defaults_loaded'] = TRUE;
+  }
+  // Assign basic defaults common for all form elements.
+  $element += array(
+    '#required' => FALSE,
+    '#attributes' => array(),
+    '#title_display' => 'before',
+  );
+
+  // Special handling if we're on the top level form element.
+  if (isset($element['#type']) && $element['#type'] == 'form') {
+    if (!empty($element['#https']) && variable_get('https', FALSE) &&
+        !url_is_external($element['#action'])) {
+      global $base_root;
+
+      // Not an external URL so ensure that it is secure.
+      $element['#action'] = str_replace('http://', 'https://', $base_root) . $element['#action'];
+    }
+
+    // Store a reference to the complete form in $form_state prior to building
+    // the form. This allows advanced #process and #after_build callbacks to
+    // perform changes elsewhere in the form.
+    $form_state['complete form'] = &$element;
+
+    // Set a flag if we have a correct form submission. This is always TRUE for
+    // programmed forms coming from drupal_form_submit(), or if the form_id coming
+    // from the POST data is set and matches the current form_id.
+    if ($form_state['programmed'] || (!empty($form_state['input']) && (isset($form_state['input']['form_id']) && ($form_state['input']['form_id'] == $form_id)))) {
+      $form_state['process_input'] = TRUE;
+    }
+    else {
+      $form_state['process_input'] = FALSE;
+    }
+
+    // All form elements should have an #array_parents property.
+    $element['#array_parents'] = array();
+  }
+
+  if (!isset($element['#id'])) {
+    $element['#id'] = drupal_html_id('edit-' . implode('-', $element['#parents']));
+  }
+  // Handle input elements.
+  if (!empty($element['#input'])) {
+    _form_builder_handle_input_element($form_id, $element, $form_state);
+  }
+  // Allow for elements to expand to multiple elements, e.g., radios,
+  // checkboxes and files.
+  if (isset($element['#process']) && !$element['#processed']) {
+    foreach ($element['#process'] as $process) {
+      $element = $process($element, $form_state, $form_state['complete form']);
+    }
+    $element['#processed'] = TRUE;
+  }
+
+  // We start off assuming all form elements are in the correct order.
+  $element['#sorted'] = TRUE;
+
+  // Recurse through all child elements.
+  $count = 0;
+  foreach (element_children($element) as $key) {
+    // Prior to checking properties of child elements, their default properties
+    // need to be loaded.
+    if (isset($element[$key]['#type']) && empty($element[$key]['#defaults_loaded']) && ($info = element_info($element[$key]['#type']))) {
+      $element[$key] += $info;
+      $element[$key]['#defaults_loaded'] = TRUE;
+    }
+
+    // Don't squash an existing tree value.
+    if (!isset($element[$key]['#tree'])) {
+      $element[$key]['#tree'] = $element['#tree'];
+    }
+
+    // Deny access to child elements if parent is denied.
+    if (isset($element['#access']) && !$element['#access']) {
+      $element[$key]['#access'] = FALSE;
+    }
+
+    // Make child elements inherit their parent's #disabled and #allow_focus
+    // values unless they specify their own.
+    foreach (array('#disabled', '#allow_focus') as $property) {
+      if (isset($element[$property]) && !isset($element[$key][$property])) {
+        $element[$key][$property] = $element[$property];
+      }
+    }
+
+    // Don't squash existing parents value.
+    if (!isset($element[$key]['#parents'])) {
+      // Check to see if a tree of child elements is present. If so,
+      // continue down the tree if required.
+      $element[$key]['#parents'] = $element[$key]['#tree'] && $element['#tree'] ? array_merge($element['#parents'], array($key)) : array($key);
+    }
+    // Ensure #array_parents follows the actual form structure.
+    $array_parents = $element['#array_parents'];
+    $array_parents[] = $key;
+    $element[$key]['#array_parents'] = $array_parents;
+
+    // Assign a decimal placeholder weight to preserve original array order.
+    if (!isset($element[$key]['#weight'])) {
+      $element[$key]['#weight'] = $count/1000;
+    }
+    else {
+      // If one of the child elements has a weight then we will need to sort
+      // later.
+      unset($element['#sorted']);
+    }
+    $element[$key] = form_builder($form_id, $element[$key], $form_state);
+    $count++;
+  }
+
+  // The #after_build flag allows any piece of a form to be altered
+  // after normal input parsing has been completed.
+  if (isset($element['#after_build']) && !isset($element['#after_build_done'])) {
+    foreach ($element['#after_build'] as $function) {
+      $element = $function($element, $form_state);
+    }
+    $element['#after_build_done'] = TRUE;
+  }
+
+  // If there is a file element, we need to flip a flag so later the
+  // form encoding can be set.
+  if (isset($element['#type']) && $element['#type'] == 'file') {
+    $form_state['has_file_element'] = TRUE;
+  }
+
+  // Final tasks for the form element after form_builder() has run for all other
+  // elements.
+  if (isset($element['#type']) && $element['#type'] == 'form') {
+    // If there is a file element, we set the form encoding.
+    if (isset($form_state['has_file_element'])) {
+      $element['#attributes']['enctype'] = 'multipart/form-data';
+    }
+
+    // If a form contains a single textfield, and the ENTER key is pressed
+    // within it, Internet Explorer submits the form with no POST data
+    // identifying any submit button. Other browsers submit POST data as though
+    // the user clicked the first button. Therefore, to be as consistent as we
+    // can be across browsers, if no 'triggering_element' has been identified
+    // yet, default it to the first button.
+    if (!$form_state['programmed'] && !isset($form_state['triggering_element']) && !empty($form_state['buttons'])) {
+      $form_state['triggering_element'] = $form_state['buttons'][0];
+    }
+
+    // If the triggering element specifies "button-level" validation and submit
+    // handlers to run instead of the default form-level ones, then add those to
+    // the form state.
+    foreach (array('validate', 'submit') as $type) {
+      if (isset($form_state['triggering_element']['#' . $type])) {
+        $form_state[$type . '_handlers'] = $form_state['triggering_element']['#' . $type];
+      }
+    }
+
+    // If the triggering element executes submit handlers, then set the form
+    // state key that's needed for those handlers to run.
+    if (!empty($form_state['triggering_element']['#executes_submit_callback'])) {
+      $form_state['submitted'] = TRUE;
+    }
+
+    // Special processing if the triggering element is a button.
+    if (isset($form_state['triggering_element']['#button_type'])) {
+      // Because there are several ways in which the triggering element could
+      // have been determined (including from input variables set by JavaScript
+      // or fallback behavior implemented for IE), and because buttons often
+      // have their #name property not derived from their #parents property, we
+      // can't assume that input processing that's happened up until here has
+      // resulted in $form_state['values'][BUTTON_NAME] being set. But it's
+      // common for forms to have several buttons named 'op' and switch on
+      // $form_state['values']['op'] during submit handler execution.
+      $form_state['values'][$form_state['triggering_element']['#name']] = $form_state['triggering_element']['#value'];
+
+      // @todo Legacy support. Remove in Drupal 8.
+      $form_state['clicked_button'] = $form_state['triggering_element'];
+    }
+  }
+  return $element;
+}
+
+/**
+ * Adds the #name and #value properties of an input element before rendering.
+ */
+function _form_builder_handle_input_element($form_id, &$element, &$form_state) {
+  if (!isset($element['#name'])) {
+    $name = array_shift($element['#parents']);
+    $element['#name'] = $name;
+    if ($element['#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.
+      $element['#name'] = 'files[' . $element['#name'] . ']';
+    }
+    elseif (count($element['#parents'])) {
+      $element['#name'] .= '[' . implode('][', $element['#parents']) . ']';
+    }
+    array_unshift($element['#parents'], $name);
+  }
+
+  // Setting #disabled to TRUE results in user input being ignored, regardless
+  // of how the element is themed or whether JavaScript is used to change the
+  // control's attributes. However, it's good UI to let the user know that input
+  // is not wanted for the control. HTML supports two attributes for this:
+  // http://www.w3.org/TR/html401/interact/forms.html#h-17.12. If a form wants
+  // to start a control off with one of these attributes for UI purposes only,
+  // but still allow input to be processed if it's sumitted, it can set the
+  // desired attribute in #attributes directly rather than using #disabled.
+  // However, developers should think carefully about the accessibility
+  // implications of doing so: if the form expects input to be enterable under
+  // some condition triggered by JavaScript, how would someone who has
+  // JavaScript disabled trigger that condition? Instead, developers should
+  // consider whether a multi-step form would be more appropriate (#disabled can
+  // be changed from step to step). If one still decides to use JavaScript to
+  // affect when a control is enabled, then it is best for accessibility for the
+  // control to be enabled in the HTML, and disabled by JavaScript on document
+  // ready.
+  if (!empty($element['#disabled'])) {
+    if (!empty($element['#allow_focus'])) {
+      $element['#attributes']['readonly'] = 'readonly';
+    }
+    else {
+      $element['#attributes']['disabled'] = 'disabled';
+    }
+  }
+
+  // With JavaScript or other easy hacking, input can be submitted even for
+  // elements with #access=FALSE or #disabled=TRUE. For security, these must
+  // not be processed. Forms that set #disabled=TRUE on an element do not
+  // expect input for the element, and even forms submitted with
+  // drupal_form_submit() must not be able to get around this. Forms that set
+  // #access=FALSE on an element usually allow access for some users, so forms
+  // submitted with drupal_form_submit() may bypass access restriction and be
+  // treated as high-privilege users instead.
+  $process_input = empty($element['#disabled']) && ($form_state['programmed'] || ($form_state['process_input'] && (!isset($element['#access']) || $element['#access'])));
+
+  // Set the element's #value property.
+  if (!isset($element['#value']) && !array_key_exists('#value', $element)) {
+    $value_callback = !empty($element['#value_callback']) ? $element['#value_callback'] : 'form_type_' . $element['#type'] . '_value';
+    if ($process_input) {
+      // Get the input for the current element. NULL values in the input need to
+      // be explicitly distinguished from missing input. (see below)
+      $input_exists = NULL;
+      $input = drupal_array_get_nested_value($form_state['input'], $element['#parents'], $input_exists);
+      // For browser-submitted forms, the submitted values do not contain values
+      // for certain elements (empty multiple select, unchecked checkbox).
+      // During initial form processing, we add explicit NULL values for such
+      // elements in $form_state['input']. When rebuilding the form, we can
+      // distinguish elements having NULL input from elements that were not part
+      // of the initially submitted form and can therefore use default values
+      // for the latter, if required. Programmatically submitted forms can
+      // submit explicit NULL values when calling drupal_form_submit(), so we do
+      // not modify $form_state['input'] for them.
+      if (!$input_exists && !$form_state['rebuild'] && !$form_state['programmed']) {
+        // Add the necessary parent keys to $form_state['input'] and sets the
+        // element's input value to NULL.
+        drupal_array_set_nested_value($form_state['input'], $element['#parents'], NULL);
+        $input_exists = TRUE;
+      }
+      // If we have input for the current element, assign it to the #value
+      // property, optionally filtered through $value_callback.
+      if ($input_exists) {
+        if (function_exists($value_callback)) {
+          $element['#value'] = $value_callback($element, $input, $form_state);
+        }
+        if (!isset($element['#value']) && isset($input)) {
+          $element['#value'] = $input;
+        }
+      }
+      // Mark all posted values for validation.
+      if (isset($element['#value']) || (!empty($element['#required']))) {
+        $element['#needs_validation'] = TRUE;
+      }
+    }
+    // Load defaults.
+    if (!isset($element['#value'])) {
+      // Call #type_value without a second argument to request default_value handling.
+      if (function_exists($value_callback)) {
+        $element['#value'] = $value_callback($element, FALSE, $form_state);
+      }
+      // Final catch. If we haven't set a value yet, use the explicit default value.
+      // Avoid image buttons (which come with garbage value), so we only get value
+      // for the button actually clicked.
+      if (!isset($element['#value']) && empty($element['#has_garbage_value'])) {
+        $element['#value'] = isset($element['#default_value']) ? $element['#default_value'] : '';
+      }
+    }
+  }
+
+  // Determine which element (if any) triggered the submission of the form and
+  // keep track of all the clickable buttons in the form for
+  // form_state_values_clean(). Enforce the same input processing restrictions
+  // as above.
+  if ($process_input) {
+    // Detect if the element triggered the submission via Ajax.
+    if (_form_element_triggered_scripted_submission($element, $form_state)) {
+      $form_state['triggering_element'] = $element;
+    }
+
+    // If the form was submitted by the browser rather than via Ajax, then it
+    // can only have been triggered by a button, and we need to determine which
+    // button within the constraints of how browsers provide this information.
+    if (isset($element['#button_type'])) {
+      // All buttons in the form need to be tracked for
+      // form_state_values_clean() and for the form_builder() code that handles
+      // a form submission containing no button information in $_POST.
+      $form_state['buttons'][] = $element;
+      if (_form_button_was_clicked($element, $form_state)) {
+        $form_state['triggering_element'] = $element;
+      }
+    }
+  }
+
+  // Set the element's value in $form_state['values'], but only, if its key
+  // does not exist yet (a #value_callback may have already populated it).
+  if (!drupal_array_nested_key_exists($form_state['values'], $element['#parents'])) {
+    form_set_value($element, $element['#value'], $form_state);
+  }
+}
+
+/**
+ * Detects if an element triggered the form submission via Ajax.
+ *
+ * This detects button or non-button controls that trigger a form submission via
+ * Ajax or some other scriptable environment. These environments can set the
+ * special input key '_triggering_element_name' to identify the triggering
+ * element. If the name alone doesn't identify the element uniquely, the input
+ * key '_triggering_element_value' may also be set to require a match on element
+ * value. An example where this is needed is if there are several buttons all
+ * named 'op', and only differing in their value.
+ */
+function _form_element_triggered_scripted_submission($element, &$form_state) {
+  if (!empty($form_state['input']['_triggering_element_name']) && $element['#name'] == $form_state['input']['_triggering_element_name']) {
+    if (empty($form_state['input']['_triggering_element_value']) || $form_state['input']['_triggering_element_value'] == $element['#value']) {
+      return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+/**
+ * Determines if a given button triggered the form submission.
+ *
+ * This detects button controls that trigger a form submission by being clicked
+ * and having the click processed by the browser rather than being captured by
+ * JavaScript. Essentially, it detects if the button's name and value are part
+ * of the POST data, but with extra code to deal with the convoluted way in
+ * which browsers submit data for image button clicks.
+ *
+ * This does not detect button clicks processed by Ajax (that is done in
+ * _form_element_triggered_scripted_submission()) and it does not detect form
+ * submissions from Internet Explorer in response to an ENTER key pressed in a
+ * textfield (form_builder() has extra code for that).
+ *
+ * Because this function contains only part of the logic needed to determine
+ * $form_state['triggering_element'], it should not be called from anywhere
+ * other than within the Form API. Form validation and submit handlers needing
+ * to know which button was clicked should get that information from
+ * $form_state['triggering_element'].
+ */
+function _form_button_was_clicked($element, &$form_state) {
+  // 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_state['input'][$element['#name']]) && $form_state['input'][$element['#name']] == $element['#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 $_POST data should be ignored.
+  elseif (!empty($element['#has_garbage_value']) && isset($element['#value']) && $element['#value'] !== '') {
+    return TRUE;
+  }
+  return FALSE;
+}
+
+/**
+ * Removes internal Form API elements and buttons from submitted form values.
+ *
+ * This function can be used when a module wants to store all submitted form
+ * values, for example, by serializing them into a single database column. In
+ * such cases, all internal Form API values and all form button elements should
+ * not be contained, and this function allows to remove them before the module
+ * proceeds to storage. Next to button elements, the following internal values
+ * are removed:
+ * - form_id
+ * - form_token
+ * - form_build_id
+ * - op
+ *
+ * @param $form_state
+ *   A keyed array containing the current state of the form, including
+ *   submitted form values; altered by reference.
+ */
+function form_state_values_clean(&$form_state) {
+  // Remove internal Form API values.
+  unset($form_state['values']['form_id'], $form_state['values']['form_token'], $form_state['values']['form_build_id'], $form_state['values']['op']);
+
+  // Remove button values.
+  // form_builder() collects all button elements in a form. We remove the button
+  // value separately for each button element.
+  foreach ($form_state['buttons'] as $button) {
+    // Remove this button's value from the submitted form values by finding
+    // the value corresponding to this button.
+    // We iterate over the #parents of this button and move a reference to
+    // each parent in $form_state['values']. For example, if #parents is:
+    //   array('foo', 'bar', 'baz')
+    // then the corresponding $form_state['values'] part will look like this:
+    // array(
+    //   'foo' => array(
+    //     'bar' => array(
+    //       'baz' => 'button_value',
+    //     ),
+    //   ),
+    // )
+    // We start by (re)moving 'baz' to $last_parent, so we are able unset it
+    // at the end of the iteration. Initially, $values will contain a
+    // reference to $form_state['values'], but in the iteration we move the
+    // reference to $form_state['values']['foo'], and finally to
+    // $form_state['values']['foo']['bar'], which is the level where we can
+    // unset 'baz' (that is stored in $last_parent).
+    $parents = $button['#parents'];
+    $last_parent = array_pop($parents);
+    $key_exists = NULL;
+    $values = &drupal_array_get_nested_value($form_state['values'], $parents, $key_exists);
+    if ($key_exists && is_array($values)) {
+      unset($values[$last_parent]);
+    }
+  }
+}
+
+/**
+ * Determines the value for an image button form element.
+ *
+ * @param $form
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input to populate the form element. If this is FALSE,
+ *   the element's default value should be returned.
+ * @param $form_state
+ *   A keyed array containing the current state of the form.
+ *
+ * @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, $input, $form_state) {
+  if ($input !== FALSE) {
+    if (!empty($input)) {
+      // 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'.
+      $input = $form_state['input'];
+      foreach (explode('[', $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($input[$element_name])) {
+          if (isset($input[$element_name . '_x'])) {
+            return $form['#return_value'];
+          }
+          return NULL;
+        }
+        $input = $input[$element_name];
+      }
+      return $form['#return_value'];
+    }
+  }
+}
+
+/**
+ * Determines the value for a checkbox form element.
+ *
+ * @param $form
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_checkbox_value($element, $input = FALSE) {
+  if ($input === FALSE) {
+    // Use #default_value as the default value of a checkbox, except change
+    // NULL to 0, because _form_builder_handle_input_element() would otherwise
+    // replace NULL with empty string, but an empty string is a potentially
+    // valid value for a checked checkbox.
+    return isset($element['#default_value']) ? $element['#default_value'] : 0;
+  }
+  else {
+    // Checked checkboxes are submitted with a value (possibly '0' or ''):
+    // http://www.w3.org/TR/html401/interact/forms.html#successful-controls.
+    // For checked checkboxes, browsers submit the string version of
+    // #return_value, but we return the original #return_value. For unchecked
+    // checkboxes, browsers submit nothing at all, but
+    // _form_builder_handle_input_element() detects this, and calls this
+    // function with $input=NULL. Returning NULL from a value callback means to
+    // use the default value, which is not what is wanted when an unchecked
+    // checkbox is submitted, so we use integer 0 as the value indicating an
+    // unchecked checkbox. Therefore, modules must not use integer 0 as a
+    // #return_value, as doing so results in the checkbox always being treated
+    // as unchecked. The string '0' is allowed for #return_value. The most
+    // common use-case for setting #return_value to either 0 or '0' is for the
+    // first option within a 0-indexed array of checkboxes, and for this,
+    // form_process_checkboxes() uses the string rather than the integer.
+    return isset($input) ? $element['#return_value'] : 0;
+  }
+}
+
+/**
+ * Determines the value for a checkboxes form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_checkboxes_value($element, $input = FALSE) {
+  if ($input === FALSE) {
+    $value = array();
+    $element += array('#default_value' => array());
+    foreach ($element['#default_value'] as $key) {
+      $value[$key] = $key;
+    }
+    return $value;
+  }
+  elseif (is_array($input)) {
+    // Programmatic form submissions use NULL to indicate that a checkbox
+    // should be unchecked; see drupal_form_submit(). We therefore remove all
+    // NULL elements from the array before constructing the return value, to
+    // simulate the behavior of web browsers (which do not send unchecked
+    // checkboxes to the server at all). This will not affect non-programmatic
+    // form submissions, since all values in $_POST are strings.
+    foreach ($input as $key => $value) {
+      if (!isset($value)) {
+        unset($input[$key]);
+      }
+    }
+    return drupal_map_assoc($input);
+  }
+  else {
+    return array();
+  }
+}
+
+/**
+ * Determines the value for a tableselect form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_tableselect_value($element, $input = FALSE) {
+  // If $element['#multiple'] == FALSE, then radio buttons are displayed and
+  // the default value handling is used.
+  if (isset($element['#multiple']) && $element['#multiple']) {
+    // Checkboxes are being displayed with the default value coming from the
+    // keys of the #default_value property. This differs from the checkboxes
+    // element which uses the array values.
+    if ($input === FALSE) {
+      $value = array();
+      $element += array('#default_value' => array());
+      foreach ($element['#default_value'] as $key => $flag) {
+        if ($flag) {
+          $value[$key] = $key;
+        }
+      }
+      return $value;
+    }
+    else {
+      return is_array($input) ? drupal_map_assoc($input) : array();
+    }
+  }
+}
+
+/**
+ * Form value callback: Determines the value for a #type radios form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   (optional) The incoming input to populate the form element. If FALSE, the
+ *   element's default value is returned. Defaults to FALSE.
+ *
+ * @return
+ *   The data that will appear in the $element_state['values'] collection for
+ *   this element.
+ */
+function form_type_radios_value(&$element, $input = FALSE) {
+  if ($input !== FALSE) {
+    // When there's user input (including NULL), return it as the value.
+    // However, if NULL is submitted, _form_builder_handle_input_element() will
+    // apply the default value, and we want that validated against #options
+    // unless it's empty. (An empty #default_value, such as NULL or FALSE, can
+    // be used to indicate that no radio button is selected by default.)
+    if (!isset($input) && !empty($element['#default_value'])) {
+      $element['#needs_validation'] = TRUE;
+    }
+    return $input;
+  }
+  else {
+    // For default value handling, simply return #default_value. Additionally,
+    // for a NULL default value, set #has_garbage_value to prevent
+    // _form_builder_handle_input_element() converting the NULL to an empty
+    // string, so that code can distinguish between nothing selected and the
+    // selection of a radio button whose value is an empty string.
+    $value = isset($element['#default_value']) ? $element['#default_value'] : NULL;
+    if (!isset($value)) {
+      $element['#has_garbage_value'] = TRUE;
+    }
+    return $value;
+  }
+}
+
+/**
+ * Determines the value for a password_confirm form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_password_confirm_value($element, $input = FALSE) {
+  if ($input === FALSE) {
+    $element += array('#default_value' => array());
+    return $element['#default_value'] + array('pass1' => '', 'pass2' => '');
+  }
+}
+
+/**
+ * Determines the value for a select form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_select_value($element, $input = FALSE) {
+  if ($input !== FALSE) {
+    if (isset($element['#multiple']) && $element['#multiple']) {
+      // If an enabled multi-select submits NULL, it means all items are
+      // unselected. A disabled multi-select always submits NULL, and the
+      // default value should be used.
+      if (empty($element['#disabled'])) {
+        return (is_array($input)) ? drupal_map_assoc($input) : array();
+      }
+      else {
+        return (isset($element['#default_value']) && is_array($element['#default_value'])) ? $element['#default_value'] : array();
+      }
+    }
+    // Non-multiple select elements may have an empty option preprended to them
+    // (see form_process_select()). When this occurs, usually #empty_value is
+    // an empty string, but some forms set #empty_value to integer 0 or some
+    // other non-string constant. PHP receives all submitted form input as
+    // strings, but if the empty option is selected, set the value to match the
+    // empty value exactly.
+    elseif (isset($element['#empty_value']) && $input === (string) $element['#empty_value']) {
+      return $element['#empty_value'];
+    }
+    else {
+      return $input;
+    }
+  }
+}
+
+/**
+ * Determines the value for a textfield form element.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_textfield_value($element, $input = FALSE) {
+  if ($input !== FALSE && $input !== NULL) {
+    // Equate $input to the form value to ensure it's marked for
+    // validation.
+    return str_replace(array("\r", "\n"), '', $input);
+  }
+}
+
+/**
+ * Determines the value for form's token value.
+ *
+ * @param $element
+ *   The form element whose value is being populated.
+ * @param $input
+ *   The incoming input 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 $element_state['values'] collection
+ *   for this element. Return nothing to use the default.
+ */
+function form_type_token_value($element, $input = FALSE) {
+  if ($input !== FALSE) {
+    return (string) $input;
+  }
+}
+
+/**
+ * Changes submitted form values during form validation.
+ *
+ * Use this function to change the submitted value of a form element in a form
+ * validation function, so that the changed value persists in $form_state
+ * through the remaining validation and submission handlers. It does not change
+ * the value in $element['#value'], only in $form_state['values'], which is
+ * where submitted values are always stored.
+ *
+ * Note that form validation functions are specified in the '#validate'
+ * component of the form array (the value of $form['#validate'] is an array of
+ * validation function names). If the form does not originate in your module,
+ * you can implement hook_form_FORM_ID_alter() to add a validation function
+ * to $form['#validate'].
+ *
+ * @param $element
+ *   The form element that should have its value updated; in most cases you can
+ *   just pass in the element from the $form array, although the only component
+ *   that is actually used is '#parents'. If constructing yourself, set
+ *   $element['#parents'] to be an array giving the path through the form
+ *   array's keys to the element whose value you want to update. For instance,
+ *   if you want to update the value of $form['elem1']['elem2'], which should be
+ *   stored in $form_state['values']['elem1']['elem2'], you would set
+ *   $element['#parents'] = array('elem1','elem2').
+ * @param $value
+ *   The new value for the form element.
+ * @param $form_state
+ *   Form state array where the value change should be recorded.
+ */
+function form_set_value($element, $value, &$form_state) {
+  drupal_array_set_nested_value($form_state['values'], $element['#parents'], $value, TRUE);
+}
+
+/**
+ * Allows PHP array processing of multiple select options with the same value.
+ *
+ * Used for form select elements which need to validate HTML option groups
+ * and multiple options which may return the same value. Associative PHP arrays
+ * cannot handle these structures, since they share a common key.
+ *
+ * @param $array
+ *   The form options array to process.
+ *
+ * @return
+ *   An array with all hierarchical elements flattened to a single array.
+ */
+function form_options_flatten($array) {
+  // Always reset static var when first entering the recursion.
+  drupal_static_reset('_form_options_flatten');
+  return _form_options_flatten($array);
+}
+
+/**
+ * Iterates over an array and returns a flat array with duplicate keys removed.
+ *
+ * This function also handles cases where objects are passed as array values.
+ */
+function _form_options_flatten($array) {
+  $return = &drupal_static(__FUNCTION__);
+
+  foreach ($array as $key => $value) {
+    if (is_object($value)) {
+      _form_options_flatten($value->option);
+    }
+    elseif (is_array($value)) {
+      _form_options_flatten($value);
+    }
+    else {
+      $return[$key] = 1;
+    }
+  }
+
+  return $return;
+}
+
+/**
+ * Processes a select list form element.
+ *
+ * This process callback is mandatory for select fields, since all user agents
+ * automatically preselect the first available option of single (non-multiple)
+ * select lists.
+ *
+ * @param $element
+ *   The form element to process. Properties used:
+ *   - #multiple: (optional) Indicates whether one or more options can be
+ *     selected. Defaults to FALSE.
+ *   - #default_value: Must be NULL or not set in case there is no value for the
+ *     element yet, in which case a first default option is inserted by default.
+ *     Whether this first option is a valid option depends on whether the field
+ *     is #required or not.
+ *   - #required: (optional) Whether the user needs to select an option (TRUE)
+ *     or not (FALSE). Defaults to FALSE.
+ *   - #empty_option: (optional) The label to show for the first default option.
+ *     By default, the label is automatically set to "- Please select -" for a
+ *     required field and "- None -" for an optional field.
+ *   - #empty_value: (optional) The value for the first default option, which is
+ *     used to determine whether the user submitted a value or not.
+ *     - If #required is TRUE, this defaults to '' (an empty string).
+ *     - If #required is not TRUE and this value isn't set, then no extra option
+ *       is added to the select control, leaving the control in a slightly
+ *       illogical state, because there's no way for the user to select nothing,
+ *       since all user agents automatically preselect the first available
+ *       option. But people are used to this being the behavior of select
+ *       controls.
+ *       @todo Address the above issue in Drupal 8.
+ *     - If #required is not TRUE and this value is set (most commonly to an
+ *       empty string), then an extra option (see #empty_option above)
+ *       representing a "non-selection" is added with this as its value.
+ *
+ * @see _form_validate()
+ */
+function form_process_select($element) {
+  // #multiple select fields need a special #name.
+  if ($element['#multiple']) {
+    $element['#attributes']['multiple'] = 'multiple';
+    $element['#attributes']['name'] = $element['#name'] . '[]';
+  }
+  // A non-#multiple select needs special handling to prevent user agents from
+  // preselecting the first option without intention. #multiple select lists do
+  // not get an empty option, as it would not make sense, user interface-wise.
+  else {
+    $required = $element['#required'];
+    // If the element is required and there is no #default_value, then add an
+    // empty option that will fail validation, so that the user is required to
+    // make a choice. Also, if there's a value for #empty_value or
+    // #empty_option, then add an option that represents emptiness.
+    if (($required && !isset($element['#default_value'])) || isset($element['#empty_value']) || isset($element['#empty_option'])) {
+      $element += array(
+        '#empty_value' => '',
+        '#empty_option' => $required ? t('- Select -') : t('- None -'),
+      );
+      // The empty option is prepended to #options and purposively not merged
+      // to prevent another option in #options mistakenly using the same value
+      // as #empty_value.
+      $empty_option = array($element['#empty_value'] => $element['#empty_option']);
+      $element['#options'] = $empty_option + $element['#options'];
+    }
+  }
+  return $element;
+}
+
+/**
+ * Returns HTML for a select form element.
+ *
+ * It is possible to group options together; to do this, change the format of
+ * $options to an associative array in which the keys are group labels, and the
+ * values are associative arrays in the normal $options format.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #options, #description, #extra,
+ *     #multiple, #required, #name, #attributes, #size.
+ *
+ * @ingroup themeable
+ */
+function theme_select($variables) {
+  $element = $variables['element'];
+  element_set_attributes($element, array('id', 'name', 'size'));
+  _form_set_class($element, array('form-select'));
+
+  return '<select' . drupal_attributes($element['#attributes']) . '>' . form_select_options($element) . '</select>';
+}
+
+/**
+ * Converts a select form element's options array into HTML.
+ *
+ * @param $element
+ *   An associative array containing the properties of the element.
+ * @param $choices
+ *   Mixed: Either an associative array of items to list as choices, or an
+ *   object with an 'option' member that is an associative array. This
+ *   parameter is only used internally and should not be passed.
+ *
+ * @return
+ *   An HTML string of options for the select form element.
+ */
+function form_select_options($element, $choices = NULL) {
+  if (!isset($choices)) {
+    $choices = $element['#options'];
+  }
+  // array_key_exists() accommodates the rare event where $element['#value'] is NULL.
+  // isset() fails in this situation.
+  $value_valid = isset($element['#value']) || array_key_exists('#value', $element);
+  $value_is_array = $value_valid && is_array($element['#value']);
+  $options = '';
+  foreach ($choices as $key => $choice) {
+    if (is_array($choice)) {
+      $options .= '<optgroup label="' . $key . '">';
+      $options .= form_select_options($element, $choice);
+      $options .= '</optgroup>';
+    }
+    elseif (is_object($choice)) {
+      $options .= form_select_options($element, $choice->option);
+    }
+    else {
+      $key = (string) $key;
+      if ($value_valid && (!$value_is_array && (string) $element['#value'] === $key || ($value_is_array && in_array($key, $element['#value'])))) {
+        $selected = ' selected="selected"';
+      }
+      else {
+        $selected = '';
+      }
+      $options .= '<option value="' . check_plain($key) . '"' . $selected . '>' . check_plain($choice) . '</option>';
+    }
+  }
+  return $options;
+}
+
+/**
+ * Returns the indexes of a select element's options matching a given key.
+ *
+ * This function is useful if you need to modify the options that are
+ * already in a form element; for example, to remove choices which are
+ * not valid because of additional filters imposed by another module.
+ * One example might be altering the choices in a taxonomy selector.
+ * To correctly handle the case of a multiple hierarchy taxonomy,
+ * #options arrays can now hold an array of objects, instead of a
+ * direct mapping of keys to labels, so that multiple choices in the
+ * selector can have the same key (and label). This makes it difficult
+ * to manipulate directly, which is why this helper function exists.
+ *
+ * This function does not support optgroups (when the elements of the
+ * #options array are themselves arrays), and will return FALSE if
+ * arrays are found. The caller must either flatten/restore or
+ * manually do their manipulations in this case, since returning the
+ * index is not sufficient, and supporting this would make the
+ * "helper" too complicated and cumbersome to be of any help.
+ *
+ * As usual with functions that can return array() or FALSE, do not
+ * forget to use === and !== if needed.
+ *
+ * @param $element
+ *   The select element to search.
+ * @param $key
+ *   The key to look for.
+ *
+ * @return
+ *   An array of indexes that match the given $key. Array will be
+ *   empty if no elements were found. FALSE if optgroups were found.
+ */
+function form_get_options($element, $key) {
+  $keys = array();
+  foreach ($element['#options'] as $index => $choice) {
+    if (is_array($choice)) {
+      return FALSE;
+    }
+    elseif (is_object($choice)) {
+      if (isset($choice->option[$key])) {
+        $keys[] = $index;
+      }
+    }
+    elseif ($index == $key) {
+      $keys[] = $index;
+    }
+  }
+  return $keys;
+}
+
+/**
+ * Returns HTML for a fieldset form element and its children.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes, #children, #collapsed, #collapsible,
+ *     #description, #id, #title, #value.
+ *
+ * @ingroup themeable
+ */
+function theme_fieldset($variables) {
+  $element = $variables['element'];
+  element_set_attributes($element, array('id'));
+  _form_set_class($element, array('form-wrapper'));
+
+  $output = '<fieldset' . drupal_attributes($element['#attributes']) . '>';
+  if (!empty($element['#title'])) {
+    // Always wrap fieldset legends in a SPAN for CSS positioning.
+    $output .= '<legend><span class="fieldset-legend">' . $element['#title'] . '</span></legend>';
+  }
+  $output .= '<div class="fieldset-wrapper">';
+  if (!empty($element['#description'])) {
+    $output .= '<div class="fieldset-description">' . $element['#description'] . '</div>';
+  }
+  $output .= $element['#children'];
+  if (isset($element['#value'])) {
+    $output .= $element['#value'];
+  }
+  $output .= '</div>';
+  $output .= "</fieldset>\n";
+  return $output;
+}
+
+/**
+ * Returns HTML for a radio button form element.
+ *
+ * Note: The input "name" attribute needs to be sanitized before output, which
+ *       is currently done by passing all attributes to drupal_attributes().
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #required, #return_value, #value, #attributes, #title,
+ *     #description
+ *
+ * @ingroup themeable
+ */
+function theme_radio($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'radio';
+  element_set_attributes($element, array('id', 'name', '#return_value' => 'value'));
+
+  if (isset($element['#return_value']) && $element['#value'] !== FALSE && $element['#value'] == $element['#return_value']) {
+    $element['#attributes']['checked'] = 'checked';
+  }
+  _form_set_class($element, array('form-radio'));
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Returns HTML for a set of radio button form elements.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #options, #description, #required,
+ *     #attributes, #children.
+ *
+ * @ingroup themeable
+ */
+function theme_radios($variables) {
+  $element = $variables['element'];
+  $attributes = array();
+  if (isset($element['#id'])) {
+    $attributes['id'] = $element['#id'];
+  }
+  $attributes['class'] = 'form-radios';
+  if (!empty($element['#attributes']['class'])) {
+    $attributes['class'] .= ' ' . implode(' ', $element['#attributes']['class']);
+  }
+  if (isset($element['#attributes']['title'])) {
+    $attributes['title'] = $element['#attributes']['title'];
+  }
+  return '<div' . drupal_attributes($attributes) . '>' . (!empty($element['#children']) ? $element['#children'] : '') . '</div>';
+}
+
+/**
+ * Expand a password_confirm field into two text boxes.
+ */
+function form_process_password_confirm($element) {
+  $element['pass1'] =  array(
+    '#type' => 'password',
+    '#title' => t('Password'),
+    '#value' => empty($element['#value']) ? NULL : $element['#value']['pass1'],
+    '#required' => $element['#required'],
+    '#attributes' => array('class' => array('password-field')),
+  );
+  $element['pass2'] =  array(
+    '#type' => 'password',
+    '#title' => t('Confirm password'),
+    '#value' => empty($element['#value']) ? NULL : $element['#value']['pass2'],
+    '#required' => $element['#required'],
+    '#attributes' => array('class' => array('password-confirm')),
+  );
+  $element['#element_validate'] = array('password_confirm_validate');
+  $element['#tree'] = TRUE;
+
+  if (isset($element['#size'])) {
+    $element['pass1']['#size'] = $element['pass2']['#size'] = $element['#size'];
+  }
+
+  return $element;
+}
+
+/**
+ * Validates a password_confirm element.
+ */
+function password_confirm_validate($element, &$element_state) {
+  $pass1 = trim($element['pass1']['#value']);
+  $pass2 = trim($element['pass2']['#value']);
+  if (!empty($pass1) || !empty($pass2)) {
+    if (strcmp($pass1, $pass2)) {
+      form_error($element, t('The specified passwords do not match.'));
+    }
+  }
+  elseif ($element['#required'] && !empty($element_state['input'])) {
+    form_error($element, t('Password field is required.'));
+  }
+
+  // Password field must be converted from a two-element array into a single
+  // string regardless of validation results.
+  form_set_value($element['pass1'], NULL, $element_state);
+  form_set_value($element['pass2'], NULL, $element_state);
+  form_set_value($element, $pass1, $element_state);
+
+  return $element;
+
+}
+
+/**
+ * Returns HTML for a date selection form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #options, #description, #required,
+ *     #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_date($variables) {
+  $element = $variables['element'];
+
+  $attributes = array();
+  if (isset($element['#id'])) {
+    $attributes['id'] = $element['#id'];
+  }
+  if (!empty($element['#attributes']['class'])) {
+    $attributes['class'] = (array) $element['#attributes']['class'];
+  }
+  $attributes['class'][] = 'container-inline';
+
+  return '<div' . drupal_attributes($attributes) . '>' . drupal_render_children($element) . '</div>';
+}
+
+/**
+ * Expands a date element into year, month, and day select elements.
+ */
+function form_process_date($element) {
+  // Default to current date
+  if (empty($element['#value'])) {
+    $element['#value'] = array(
+      'day' => format_date(REQUEST_TIME, 'custom', 'j'),
+      'month' => format_date(REQUEST_TIME, 'custom', 'n'),
+      'year' => format_date(REQUEST_TIME, 'custom', 'Y'),
+    );
+  }
+
+  $element['#tree'] = TRUE;
+
+  // Determine the order of day, month, year in the site's chosen date format.
+  $format = variable_get('date_format_short', 'm/d/Y - H:i');
+  $sort = array();
+  $sort['day'] = max(strpos($format, 'd'), strpos($format, 'j'));
+  $sort['month'] = max(strpos($format, 'm'), strpos($format, 'M'));
+  $sort['year'] = strpos($format, 'Y');
+  asort($sort);
+  $order = array_keys($sort);
+
+  // Output multi-selector for date.
+  foreach ($order as $type) {
+    switch ($type) {
+      case 'day':
+        $options = drupal_map_assoc(range(1, 31));
+        $title = t('Day');
+        break;
+
+      case 'month':
+        $options = drupal_map_assoc(range(1, 12), 'map_month');
+        $title = t('Month');
+        break;
+
+      case 'year':
+        $options = drupal_map_assoc(range(1900, 2050));
+        $title = t('Year');
+        break;
+    }
+
+    $element[$type] = array(
+      '#type' => 'select',
+      '#title' => $title,
+      '#title_display' => 'invisible',
+      '#value' => $element['#value'][$type],
+      '#attributes' => $element['#attributes'],
+      '#options' => $options,
+    );
+  }
+
+  return $element;
+}
+
+/**
+ * Validates the date type to prevent invalid dates (e.g., February 30, 2006).
+ */
+function date_validate($element) {
+  if (!checkdate($element['#value']['month'], $element['#value']['day'], $element['#value']['year'])) {
+    form_error($element, t('The specified date is invalid.'));
+  }
+}
+
+/**
+ * Helper function for usage with drupal_map_assoc to display month names.
+ */
+function map_month($month) {
+  $months = &drupal_static(__FUNCTION__, array(
+    1 => 'Jan',
+    2 => 'Feb',
+    3 => 'Mar',
+    4 => 'Apr',
+    5 => 'May',
+    6 => 'Jun',
+    7 => 'Jul',
+    8 => 'Aug',
+    9 => 'Sep',
+    10 => 'Oct',
+    11 => 'Nov',
+    12 => 'Dec',
+  ));
+  return t($months[$month]);
+}
+
+/**
+ * Sets the value for a weight element, with zero as a default.
+ */
+function weight_value(&$form) {
+  if (isset($form['#default_value'])) {
+    $form['#value'] = $form['#default_value'];
+  }
+  else {
+    $form['#value'] = 0;
+  }
+}
+
+/**
+ * Expands a radios element into individual radio elements.
+ */
+function form_process_radios($element) {
+  if (count($element['#options']) > 0) {
+    $weight = 0;
+    foreach ($element['#options'] as $key => $choice) {
+      // Maintain order of options as defined in #options, in case the element
+      // defines custom option sub-elements, but does not define all option
+      // sub-elements.
+      $weight += 0.001;
+
+      $element += array($key => array());
+      // Generate the parents as the autogenerator does, so we will have a
+      // unique id for each radio button.
+      $parents_for_id = array_merge($element['#parents'], array($key));
+      $element[$key] += array(
+        '#type' => 'radio',
+        '#title' => $choice,
+        // The key is sanitized in drupal_attributes() during output from the
+        // theme function.
+        '#return_value' => $key,
+        // Use default or FALSE. A value of FALSE means that the radio button is
+        // not 'checked'.
+        '#default_value' => isset($element['#default_value']) ? $element['#default_value'] : FALSE,
+        '#attributes' => $element['#attributes'],
+        '#parents' => $element['#parents'],
+        '#id' => drupal_html_id('edit-' . implode('-', $parents_for_id)),
+        '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
+        '#weight' => $weight,
+      );
+    }
+  }
+  return $element;
+}
+
+/**
+ * Returns HTML for a checkbox form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #return_value, #description, #required,
+ *     #attributes, #checked.
+ *
+ * @ingroup themeable
+ */
+function theme_checkbox($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'checkbox';
+  element_set_attributes($element, array('id', 'name', '#return_value' => 'value'));
+
+  // Unchecked checkbox has #value of integer 0.
+  if (!empty($element['#checked'])) {
+    $element['#attributes']['checked'] = 'checked';
+  }
+  _form_set_class($element, array('form-checkbox'));
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Returns HTML for a set of checkbox form elements.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #children, #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_checkboxes($variables) {
+  $element = $variables['element'];
+  $attributes = array();
+  if (isset($element['#id'])) {
+    $attributes['id'] = $element['#id'];
+  }
+  $attributes['class'][] = 'form-checkboxes';
+  if (!empty($element['#attributes']['class'])) {
+    $attributes['class'] = array_merge($attributes['class'], $element['#attributes']['class']);
+  }
+  if (isset($element['#attributes']['title'])) {
+    $attributes['title'] = $element['#attributes']['title'];
+  }
+  return '<div' . drupal_attributes($attributes) . '>' . (!empty($element['#children']) ? $element['#children'] : '') . '</div>';
+}
+
+/**
+ * Adds form element theming to an element if its title or description is set.
+ *
+ * This is used as a pre render function for checkboxes and radios.
+ */
+function form_pre_render_conditional_form_element($element) {
+  $t = get_t();
+  // Set the element's title attribute to show #title as a tooltip, if needed.
+  if (isset($element['#title']) && $element['#title_display'] == 'attribute') {
+    $element['#attributes']['title'] = $element['#title'];
+    if (!empty($element['#required'])) {
+      // Append an indication that this field is required.
+      $element['#attributes']['title'] .= ' (' . $t('Required') . ')';
+    }
+  }
+
+  if (isset($element['#title']) || isset($element['#description'])) {
+    $element['#theme_wrappers'][] = 'form_element';
+  }
+  return $element;
+}
+
+/**
+ * Sets the #checked property of a checkbox element.
+ */
+function form_process_checkbox($element, $form_state) {
+  $value = $element['#value'];
+  $return_value = $element['#return_value'];
+  // On form submission, the #value of an available and enabled checked
+  // checkbox is #return_value, and the #value of an available and enabled
+  // unchecked checkbox is integer 0. On not submitted forms, and for
+  // checkboxes with #access=FALSE or #disabled=TRUE, the #value is
+  // #default_value (integer 0 if #default_value is NULL). Most of the time,
+  // a string comparison of #value and #return_value is sufficient for
+  // determining the "checked" state, but a value of TRUE always means checked
+  // (even if #return_value is 'foo'), and a value of FALSE or integer 0 always
+  // means unchecked (even if #return_value is '' or '0').
+  if ($value === TRUE || $value === FALSE || $value === 0) {
+    $element['#checked'] = (bool) $value;
+  }
+  else {
+    // Compare as strings, so that 15 is not considered equal to '15foo', but 1
+    // is considered equal to '1'. This cast does not imply that either #value
+    // or #return_value is expected to be a string.
+    $element['#checked'] = ((string) $value === (string) $return_value);
+  }
+  return $element;
+}
+
+/**
+ * Processes a checkboxes form element.
+ */
+function form_process_checkboxes($element) {
+  $value = is_array($element['#value']) ? $element['#value'] : array();
+  $element['#tree'] = TRUE;
+  if (count($element['#options']) > 0) {
+    if (!isset($element['#default_value']) || $element['#default_value'] == 0) {
+      $element['#default_value'] = array();
+    }
+    $weight = 0;
+    foreach ($element['#options'] as $key => $choice) {
+      // Integer 0 is not a valid #return_value, so use '0' instead.
+      // @see form_type_checkbox_value().
+      // @todo For Drupal 8, cast all integer keys to strings for consistency
+      //   with form_process_radios().
+      if ($key === 0) {
+        $key = '0';
+      }
+      // Maintain order of options as defined in #options, in case the element
+      // defines custom option sub-elements, but does not define all option
+      // sub-elements.
+      $weight += 0.001;
+
+      $element += array($key => array());
+      $element[$key] += array(
+        '#type' => 'checkbox',
+        '#title' => $choice,
+        '#return_value' => $key,
+        '#default_value' => isset($value[$key]) ? $key : NULL,
+        '#attributes' => $element['#attributes'],
+        '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
+        '#weight' => $weight,
+      );
+    }
+  }
+  return $element;
+}
+
+/**
+ * Processes a form actions container element.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   form actions container.
+ * @param $form_state
+ *   The $form_state array for the form this element belongs to.
+ *
+ * @return
+ *   The processed element.
+ */
+function form_process_actions($element, &$form_state) {
+  $element['#attributes']['class'][] = 'form-actions';
+  return $element;
+}
+
+/**
+ * Processes a container element.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   container.
+ * @param $form_state
+ *   The $form_state array for the form this element belongs to.
+ *
+ * @return
+ *   The processed element.
+ */
+function form_process_container($element, &$form_state) {
+  // Generate the ID of the element if it's not explicitly given.
+  if (!isset($element['#id'])) {
+    $element['#id'] = drupal_html_id(implode('-', $element['#parents']) . '-wrapper');
+  }
+  return $element;
+}
+
+/**
+ * Returns HTML to wrap child elements in a container.
+ *
+ * Used for grouped form items. Can also be used as a #theme_wrapper for any
+ * renderable element, to surround it with a <div> and add attributes such as
+ * classes or an HTML id.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #id, #attributes, #children.
+ *
+ * @ingroup themeable
+ */
+function theme_container($variables) {
+  $element = $variables['element'];
+
+  // Special handling for form elements.
+  if (isset($element['#array_parents'])) {
+    // Assign an html ID.
+    if (!isset($element['#attributes']['id'])) {
+      $element['#attributes']['id'] = $element['#id'];
+    }
+    // Add the 'form-wrapper' class.
+    $element['#attributes']['class'][] = 'form-wrapper';
+  }
+
+  return '<div' . drupal_attributes($element['#attributes']) . '>' . $element['#children'] . '</div>';
+}
+
+/**
+ * Returns HTML for a table with radio buttons or checkboxes.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties and children of
+ *     the tableselect element. Properties used: #header, #options, #empty,
+ *     and #js_select. The #options property is an array of selection options;
+ *     each array element of #options is an array of properties. These
+ *     properties can include #attributes, which is added to the
+ *     table row's HTML attributes; see theme_table(). An example of per-row
+ *     options:
+ *     @code
+ *     $options = array(
+ *       array(
+ *         'title' => 'How to Learn Drupal',
+ *         'content_type' => 'Article',
+ *         'status' => 'published',
+ *         '#attributes' => array('class' => array('article-row')),
+ *       ),
+ *       array(
+ *         'title' => 'Privacy Policy',
+ *         'content_type' => 'Page',
+ *         'status' => 'published',
+ *         '#attributes' => array('class' => array('page-row')),
+ *       ),
+ *     );
+ *     $header = array(
+ *       'title' => t('Title'),
+ *       'content_type' => t('Content type'),
+ *       'status' => t('Status'),
+ *     );
+ *     $form['table'] = array(
+ *       '#type' => 'tableselect',
+ *       '#header' => $header,
+ *       '#options' => $options,
+ *       '#empty' => t('No content available.'),
+ *     );
+ *     @endcode
+ *
+ * @ingroup themeable
+ */
+function theme_tableselect($variables) {
+  $element = $variables['element'];
+  $rows = array();
+  $header = $element['#header'];
+  if (!empty($element['#options'])) {
+    // Generate a table row for each selectable item in #options.
+    foreach (element_children($element) as $key) {
+      $row = array();
+
+      $row['data'] = array();
+      if (isset($element['#options'][$key]['#attributes'])) {
+        $row += $element['#options'][$key]['#attributes'];
+      }
+      // Render the checkbox / radio element.
+      $row['data'][] = drupal_render($element[$key]);
+
+      // As theme_table only maps header and row columns by order, create the
+      // correct order by iterating over the header fields.
+      foreach ($element['#header'] as $fieldname => $title) {
+        $row['data'][] = $element['#options'][$key][$fieldname];
+      }
+      $rows[] = $row;
+    }
+    // Add an empty header or a "Select all" checkbox to provide room for the
+    // checkboxes/radios in the first table column.
+    if ($element['#js_select']) {
+      // Add a "Select all" checkbox.
+      drupal_add_js('misc/tableselect.js');
+      array_unshift($header, array('class' => array('select-all')));
+    }
+    else {
+      // Add an empty header when radio buttons are displayed or a "Select all"
+      // checkbox is not desired.
+      array_unshift($header, '');
+    }
+  }
+  return theme('table', array('header' => $header, 'rows' => $rows, 'empty' => $element['#empty'], 'attributes' => $element['#attributes']));
+}
+
+/**
+ * Creates checkbox or radio elements to populate a tableselect table.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   tableselect element.
+ *
+ * @return
+ *   The processed element.
+ */
+function form_process_tableselect($element) {
+
+  if ($element['#multiple']) {
+    $value = is_array($element['#value']) ? $element['#value'] : array();
+  }
+  else {
+    // Advanced selection behavior makes no sense for radios.
+    $element['#js_select'] = FALSE;
+  }
+
+  $element['#tree'] = TRUE;
+
+  if (count($element['#options']) > 0) {
+    if (!isset($element['#default_value']) || $element['#default_value'] === 0) {
+      $element['#default_value'] = array();
+    }
+
+    // Create a checkbox or radio for each item in #options in such a way that
+    // the value of the tableselect element behaves as if it had been of type
+    // checkboxes or radios.
+    foreach ($element['#options'] as $key => $choice) {
+      // Do not overwrite manually created children.
+      if (!isset($element[$key])) {
+        if ($element['#multiple']) {
+          $title = '';
+          if (!empty($element['#options'][$key]['title']['data']['#title'])) {
+            $title = t('Update @title', array(
+              '@title' => $element['#options'][$key]['title']['data']['#title'],
+            ));
+          }
+          $element[$key] = array(
+            '#type' => 'checkbox',
+            '#title' => $title,
+            '#title_display' => 'invisible',
+            '#return_value' => $key,
+            '#default_value' => isset($value[$key]) ? $key : NULL,
+            '#attributes' => $element['#attributes'],
+          );
+        }
+        else {
+          // Generate the parents as the autogenerator does, so we will have a
+          // unique id for each radio button.
+          $parents_for_id = array_merge($element['#parents'], array($key));
+          $element[$key] = array(
+            '#type' => 'radio',
+            '#title' => '',
+            '#return_value' => $key,
+            '#default_value' => ($element['#default_value'] == $key) ? $key : NULL,
+            '#attributes' => $element['#attributes'],
+            '#parents' => $element['#parents'],
+            '#id' => drupal_html_id('edit-' . implode('-', $parents_for_id)),
+            '#ajax' => isset($element['#ajax']) ? $element['#ajax'] : NULL,
+          );
+        }
+        if (isset($element['#options'][$key]['#weight'])) {
+          $element[$key]['#weight'] = $element['#options'][$key]['#weight'];
+        }
+      }
+    }
+  }
+  else {
+    $element['#value'] = array();
+  }
+  return $element;
+}
+
+/**
+ * Processes a machine-readable name form element.
+ *
+ * @param $element
+ *   The form element to process. Properties used:
+ *   - #machine_name: An associative array containing:
+ *     - exists: A function name to invoke for checking whether a submitted
+ *       machine name value already exists. The submitted value is passed as
+ *       argument. In most cases, an existing API or menu argument loader
+ *       function can be re-used. The callback is only invoked, if the submitted
+ *       value differs from the element's #default_value.
+ *     - source: (optional) The #array_parents of the form element containing
+ *       the human-readable name (i.e., as contained in the $form structure) to
+ *       use as source for the machine name. Defaults to array('name').
+ *     - label: (optional) A text to display as label for the machine name value
+ *       after the human-readable name form element. Defaults to "Machine name".
+ *     - replace_pattern: (optional) A regular expression (without delimiters)
+ *       matching disallowed characters in the machine name. Defaults to
+ *       '[^a-z0-9_]+'.
+ *     - replace: (optional) A character to replace disallowed characters in the
+ *       machine name via JavaScript. Defaults to '_' (underscore). When using a
+ *       different character, 'replace_pattern' needs to be set accordingly.
+ *     - error: (optional) A custom form error message string to show, if the
+ *       machine name contains disallowed characters.
+ *     - standalone: (optional) Whether the live preview should stay in its own
+ *       form element rather than in the suffix of the source element. Defaults
+ *       to FALSE.
+ *   - #maxlength: (optional) Should be set to the maximum allowed length of the
+ *     machine name. Defaults to 64.
+ *   - #disabled: (optional) Should be set to TRUE in case an existing machine
+ *     name must not be changed after initial creation.
+ */
+function form_process_machine_name($element, &$form_state) {
+  // Apply default form element properties.
+  $element += array(
+    '#title' => t('Machine-readable name'),
+    '#description' => t('A unique machine-readable name. Can only contain lowercase letters, numbers, and underscores.'),
+    '#machine_name' => array(),
+    '#field_prefix' => '',
+    '#field_suffix' => '',
+    '#suffix' => '',
+  );
+  // A form element that only wants to set one #machine_name property (usually
+  // 'source' only) would leave all other properties undefined, if the defaults
+  // were defined in hook_element_info(). Therefore, we apply the defaults here.
+  $element['#machine_name'] += array(
+    'source' => array('name'),
+    'target' => '#' . $element['#id'],
+    'label' => t('Machine name'),
+    'replace_pattern' => '[^a-z0-9_]+',
+    'replace' => '_',
+    'standalone' => FALSE,
+    'field_prefix' => $element['#field_prefix'],
+    'field_suffix' => $element['#field_suffix'],
+  );
+
+  // By default, machine names are restricted to Latin alphanumeric characters.
+  // So, default to LTR directionality.
+  if (!isset($element['#attributes'])) {
+    $element['#attributes'] = array();
+  }
+  $element['#attributes'] += array('dir' => 'ltr');
+
+  // The source element defaults to array('name'), but may have been overidden.
+  if (empty($element['#machine_name']['source'])) {
+    return $element;
+  }
+
+  // Retrieve the form element containing the human-readable name from the
+  // complete form in $form_state. By reference, because we may need to append
+  // a #field_suffix that will hold the live preview.
+  $key_exists = NULL;
+  $source = drupal_array_get_nested_value($form_state['complete form'], $element['#machine_name']['source'], $key_exists);
+  if (!$key_exists) {
+    return $element;
+  }
+
+  $suffix_id = $source['#id'] . '-machine-name-suffix';
+  $element['#machine_name']['suffix'] = '#' . $suffix_id;
+
+  if ($element['#machine_name']['standalone']) {
+    $element['#suffix'] .= ' <small id="' . $suffix_id . '">&nbsp;</small>';
+  }
+  else {
+    // Append a field suffix to the source form element, which will contain
+    // the live preview of the machine name.
+    $source += array('#field_suffix' => '');
+    $source['#field_suffix'] .= ' <small id="' . $suffix_id . '">&nbsp;</small>';
+
+    $parents = array_merge($element['#machine_name']['source'], array('#field_suffix'));
+    drupal_array_set_nested_value($form_state['complete form'], $parents, $source['#field_suffix']);
+  }
+
+  $js_settings = array(
+    'type' => 'setting',
+    'data' => array(
+      'machineName' => array(
+        '#' . $source['#id'] => $element['#machine_name'],
+      ),
+    ),
+  );
+  $element['#attached']['js'][] = 'misc/machine-name.js';
+  $element['#attached']['js'][] = $js_settings;
+
+  return $element;
+}
+
+/**
+ * Form element validation handler for machine_name elements.
+ *
+ * Note that #maxlength is validated by _form_validate() already.
+ */
+function form_validate_machine_name(&$element, &$form_state) {
+  // Verify that the machine name not only consists of replacement tokens.
+  if (preg_match('@^' . $element['#machine_name']['replace'] . '+$@', $element['#value'])) {
+    form_error($element, t('The machine-readable name must contain unique characters.'));
+  }
+
+  // Verify that the machine name contains no disallowed characters.
+  if (preg_match('@' . $element['#machine_name']['replace_pattern'] . '@', $element['#value'])) {
+    if (!isset($element['#machine_name']['error'])) {
+      // Since a hyphen is the most common alternative replacement character,
+      // a corresponding validation error message is supported here.
+      if ($element['#machine_name']['replace'] == '-') {
+        form_error($element, t('The machine-readable name must contain only lowercase letters, numbers, and hyphens.'));
+      }
+      // Otherwise, we assume the default (underscore).
+      else {
+        form_error($element, t('The machine-readable name must contain only lowercase letters, numbers, and underscores.'));
+      }
+    }
+    else {
+      form_error($element, $element['#machine_name']['error']);
+    }
+  }
+
+  // Verify that the machine name is unique.
+  if ($element['#default_value'] !== $element['#value']) {
+    $function = $element['#machine_name']['exists'];
+    if ($function($element['#value'], $element, $form_state)) {
+      form_error($element, t('The machine-readable name is already in use. It must be unique.'));
+    }
+  }
+}
+
+/**
+ * Arranges fieldsets into groups.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   fieldset. Note that $element must be taken by reference here, so processed
+ *   child elements are taken over into $form_state.
+ * @param $form_state
+ *   The $form_state array for the form this fieldset belongs to.
+ *
+ * @return
+ *   The processed element.
+ */
+function form_process_fieldset(&$element, &$form_state) {
+  $parents = implode('][', $element['#parents']);
+
+  // Each fieldset forms a new group. The #type 'vertical_tabs' basically only
+  // injects a new fieldset.
+  $form_state['groups'][$parents]['#group_exists'] = TRUE;
+  $element['#groups'] = &$form_state['groups'];
+
+  // Process vertical tabs group member fieldsets.
+  if (isset($element['#group'])) {
+    // Add this fieldset to the defined group (by reference).
+    $group = $element['#group'];
+    $form_state['groups'][$group][] = &$element;
+  }
+
+  // Contains form element summary functionalities.
+  $element['#attached']['library'][] = array('system', 'drupal.form');
+
+  // The .form-wrapper class is required for #states to treat fieldsets like
+  // containers.
+  if (!isset($element['#attributes']['class'])) {
+    $element['#attributes']['class'] = array();
+  }
+
+  // Collapsible fieldsets
+  if (!empty($element['#collapsible'])) {
+    $element['#attached']['library'][] = array('system', 'drupal.collapse');
+    $element['#attributes']['class'][] = 'collapsible';
+    if (!empty($element['#collapsed'])) {
+      $element['#attributes']['class'][] = 'collapsed';
+    }
+  }
+
+  return $element;
+}
+
+/**
+ * Adds members of this group as actual elements for rendering.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   fieldset.
+ *
+ * @return
+ *   The modified element with all group members.
+ */
+function form_pre_render_fieldset($element) {
+  // Fieldsets may be rendered outside of a Form API context.
+  if (!isset($element['#parents']) || !isset($element['#groups'])) {
+    return $element;
+  }
+  // Inject group member elements belonging to this group.
+  $parents = implode('][', $element['#parents']);
+  $children = element_children($element['#groups'][$parents]);
+  if (!empty($children)) {
+    foreach ($children as $key) {
+      // Break references and indicate that the element should be rendered as
+      // group member.
+      $child = (array) $element['#groups'][$parents][$key];
+      $child['#group_fieldset'] = TRUE;
+      // Inject the element as new child element.
+      $element[] = $child;
+
+      $sort = TRUE;
+    }
+    // Re-sort the element's children if we injected group member elements.
+    if (isset($sort)) {
+      $element['#sorted'] = FALSE;
+    }
+  }
+
+  if (isset($element['#group'])) {
+    $group = $element['#group'];
+    // If this element belongs to a group, but the group-holding element does
+    // not exist, we need to render it (at its original location).
+    if (!isset($element['#groups'][$group]['#group_exists'])) {
+      // Intentionally empty to clarify the flow; we simply return $element.
+    }
+    // If we injected this element into the group, then we want to render it.
+    elseif (!empty($element['#group_fieldset'])) {
+      // Intentionally empty to clarify the flow; we simply return $element.
+    }
+    // Otherwise, this element belongs to a group and the group exists, so we do
+    // not render it.
+    elseif (element_children($element['#groups'][$group])) {
+      $element['#printed'] = TRUE;
+    }
+  }
+
+  return $element;
+}
+
+/**
+ * Creates a group formatted as vertical tabs.
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   fieldset.
+ * @param $form_state
+ *   The $form_state array for the form this vertical tab widget belongs to.
+ *
+ * @return
+ *   The processed element.
+ */
+function form_process_vertical_tabs($element, &$form_state) {
+  // Inject a new fieldset as child, so that form_process_fieldset() processes
+  // this fieldset like any other fieldset.
+  $element['group'] = array(
+    '#type' => 'fieldset',
+    '#theme_wrappers' => array(),
+    '#parents' => $element['#parents'],
+  );
+
+  // The JavaScript stores the currently selected tab in this hidden
+  // field so that the active tab can be restored the next time the
+  // form is rendered, e.g. on preview pages or when form validation
+  // fails.
+  $name = implode('__', $element['#parents']);
+  if (isset($form_state['values'][$name . '__active_tab'])) {
+    $element['#default_tab'] = $form_state['values'][$name . '__active_tab'];
+  }
+  $element[$name . '__active_tab'] = array(
+    '#type' => 'hidden',
+    '#default_value' => $element['#default_tab'],
+    '#attributes' => array('class' => array('vertical-tabs-active-tab')),
+  );
+
+  return $element;
+}
+
+/**
+ * Returns HTML for an element's children fieldsets as vertical tabs.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties and children of
+ *     the fieldset. Properties used: #children.
+ *
+ * @ingroup themeable
+ */
+function theme_vertical_tabs($variables) {
+  $element = $variables['element'];
+  // Add required JavaScript and Stylesheet.
+  drupal_add_library('system', 'drupal.vertical-tabs');
+
+  $output = '<h2 class="element-invisible">' . t('Vertical Tabs') . '</h2>';
+  $output .= '<div class="vertical-tabs-panes">' . $element['#children'] . '</div>';
+  return $output;
+}
+
+/**
+ * Returns HTML for a submit button form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes, #button_type, #name, #value.
+ *
+ * @ingroup themeable
+ */
+function theme_submit($variables) {
+  return theme('button', $variables['element']);
+}
+
+/**
+ * Returns HTML for a button form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes, #button_type, #name, #value.
+ *
+ * @ingroup themeable
+ */
+function theme_button($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'submit';
+  element_set_attributes($element, array('id', 'name', 'value'));
+
+  $element['#attributes']['class'][] = 'form-' . $element['#button_type'];
+  if (!empty($element['#attributes']['disabled'])) {
+    $element['#attributes']['class'][] = 'form-button-disabled';
+  }
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Returns HTML for an image button form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes, #button_type, #name, #value, #title, #src.
+ *
+ * @ingroup themeable
+ */
+function theme_image_button($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'image';
+  element_set_attributes($element, array('id', 'name', 'value'));
+
+  $element['#attributes']['src'] = file_create_url($element['#src']);
+  if (!empty($element['#title'])) {
+    $element['#attributes']['alt'] = $element['#title'];
+    $element['#attributes']['title'] = $element['#title'];
+  }
+
+  $element['#attributes']['class'][] = 'form-' . $element['#button_type'];
+  if (!empty($element['#attributes']['disabled'])) {
+    $element['#attributes']['class'][] = 'form-button-disabled';
+  }
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Returns HTML for a hidden form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #name, #value, #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_hidden($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'hidden';
+  element_set_attributes($element, array('name', 'value'));
+  return '<input' . drupal_attributes($element['#attributes']) . " />\n";
+}
+
+/**
+ * Returns HTML for a textfield form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #description, #size, #maxlength,
+ *     #required, #attributes, #autocomplete_path.
+ *
+ * @ingroup themeable
+ */
+function theme_textfield($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'text';
+  element_set_attributes($element, array('id', 'name', 'value', 'size', 'maxlength'));
+  _form_set_class($element, array('form-text'));
+
+  $extra = '';
+  if ($element['#autocomplete_path'] && drupal_valid_path($element['#autocomplete_path'])) {
+    drupal_add_library('system', 'drupal.autocomplete');
+    $element['#attributes']['class'][] = 'form-autocomplete';
+
+    $attributes = array();
+    $attributes['type'] = 'hidden';
+    $attributes['id'] = $element['#attributes']['id'] . '-autocomplete';
+    $attributes['value'] = url($element['#autocomplete_path'], array('absolute' => TRUE));
+    $attributes['disabled'] = 'disabled';
+    $attributes['class'][] = 'autocomplete';
+    $extra = '<input' . drupal_attributes($attributes) . ' />';
+  }
+
+  $output = '<input' . drupal_attributes($element['#attributes']) . ' />';
+
+  return $output . $extra;
+}
+
+/**
+ * Returns HTML for a form.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #action, #method, #attributes, #children
+ *
+ * @ingroup themeable
+ */
+function theme_form($variables) {
+  $element = $variables['element'];
+  if (isset($element['#action'])) {
+    $element['#attributes']['action'] = drupal_strip_dangerous_protocols($element['#action']);
+  }
+  element_set_attributes($element, array('method', 'id'));
+  if (empty($element['#attributes']['accept-charset'])) {
+    $element['#attributes']['accept-charset'] = "UTF-8";
+  }
+  // Anonymous DIV to satisfy XHTML compliance.
+  return '<form' . drupal_attributes($element['#attributes']) . '><div>' . $element['#children'] . '</div></form>';
+}
+
+/**
+ * Returns HTML for a textarea form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #description, #rows, #cols, #required,
+ *     #attributes
+ *
+ * @ingroup themeable
+ */
+function theme_textarea($variables) {
+  $element = $variables['element'];
+  element_set_attributes($element, array('id', 'name', 'cols', 'rows'));
+  _form_set_class($element, array('form-textarea'));
+
+  $wrapper_attributes = array(
+    'class' => array('form-textarea-wrapper'),
+  );
+
+  // Add resizable behavior.
+  if (!empty($element['#resizable'])) {
+    drupal_add_library('system', 'drupal.textarea');
+    $wrapper_attributes['class'][] = 'resizable';
+  }
+
+  $output = '<div' . drupal_attributes($wrapper_attributes) . '>';
+  $output .= '<textarea' . drupal_attributes($element['#attributes']) . '>' . check_plain($element['#value']) . '</textarea>';
+  $output .= '</div>';
+  return $output;
+}
+
+/**
+ * Returns HTML for a password form element.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #value, #description, #size, #maxlength,
+ *     #required, #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_password($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'password';
+  element_set_attributes($element, array('id', 'name', 'size', 'maxlength'));
+  _form_set_class($element, array('form-text'));
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Expands a weight element into a select element.
+ */
+function form_process_weight($element) {
+  $element['#is_weight'] = TRUE;
+
+  // If the number of options is small enough, use a select field.
+  $max_elements = variable_get('drupal_weight_select_max', DRUPAL_WEIGHT_SELECT_MAX);
+  if ($element['#delta'] <= $max_elements) {
+    $element['#type'] = 'select';
+    for ($n = (-1 * $element['#delta']); $n <= $element['#delta']; $n++) {
+      $weights[$n] = $n;
+    }
+    $element['#options'] = $weights;
+    $element += element_info('select');
+  }
+  // Otherwise, use a text field.
+  else {
+    $element['#type'] = 'textfield';
+    // Use a field big enough to fit most weights.
+    $element['#size'] = 10;
+    $element['#element_validate'] = array('element_validate_integer');
+    $element += element_info('textfield');
+  }
+
+  return $element;
+}
+
+/**
+ * Returns HTML for a file upload form element.
+ *
+ * For assistance with handling the uploaded file correctly, see the API
+ * provided by file.inc.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #name, #size, #description, #required,
+ *     #attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_file($variables) {
+  $element = $variables['element'];
+  $element['#attributes']['type'] = 'file';
+  element_set_attributes($element, array('id', 'name', 'size'));
+  _form_set_class($element, array('form-file'));
+
+  return '<input' . drupal_attributes($element['#attributes']) . ' />';
+}
+
+/**
+ * Returns HTML for a form element.
+ *
+ * Each form element is wrapped in a DIV container having the following CSS
+ * classes:
+ * - form-item: Generic for all form elements.
+ * - form-type-#type: The internal element #type.
+ * - form-item-#name: The internal form element #name (usually derived from the
+ *   $form structure and set via form_builder()).
+ * - form-disabled: Only set if the form element is #disabled.
+ *
+ * In addition to the element itself, the DIV contains a label for the element
+ * based on the optional #title_display property, and an optional #description.
+ *
+ * The optional #title_display property can have these values:
+ * - before: The label is output before the element. This is the default.
+ *   The label includes the #title and the required marker, if #required.
+ * - after: The label is output after the element. For example, this is used
+ *   for radio and checkbox #type elements as set in system_element_info().
+ *   If the #title is empty but the field is #required, the label will
+ *   contain only the required marker.
+ * - invisible: Labels are critical for screen readers to enable them to
+ *   properly navigate through forms but can be visually distracting. This
+ *   property hides the label for everyone except screen readers.
+ * - attribute: Set the title attribute on the element to create a tooltip
+ *   but output no label element. This is supported only for checkboxes
+ *   and radios in form_pre_render_conditional_form_element(). It is used
+ *   where a visual label is not needed, such as a table of checkboxes where
+ *   the row and column provide the context. The tooltip will include the
+ *   title and required marker.
+ *
+ * If the #title property is not set, then the label and any required marker
+ * will not be output, regardless of the #title_display or #required values.
+ * This can be useful in cases such as the password_confirm element, which
+ * creates children elements that have their own labels and required markers,
+ * but the parent element should have neither. Use this carefully because a
+ * field without an associated label can cause accessibility challenges.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #title, #title_display, #description, #id, #required,
+ *     #children, #type, #name.
+ *
+ * @ingroup themeable
+ */
+function theme_form_element($variables) {
+  $element = &$variables['element'];
+
+  // This function is invoked as theme wrapper, but the rendered form element
+  // may not necessarily have been processed by form_builder().
+  $element += array(
+    '#title_display' => 'before',
+  );
+
+  // Add element #id for #type 'item'.
+  if (isset($element['#markup']) && !empty($element['#id'])) {
+    $attributes['id'] = $element['#id'];
+  }
+  // Add element's #type and #name as class to aid with JS/CSS selectors.
+  $attributes['class'] = array('form-item');
+  if (!empty($element['#type'])) {
+    $attributes['class'][] = 'form-type-' . strtr($element['#type'], '_', '-');
+  }
+  if (!empty($element['#name'])) {
+    $attributes['class'][] = 'form-item-' . strtr($element['#name'], array(' ' => '-', '_' => '-', '[' => '-', ']' => ''));
+  }
+  // Add a class for disabled elements to facilitate cross-browser styling.
+  if (!empty($element['#attributes']['disabled'])) {
+    $attributes['class'][] = 'form-disabled';
+  }
+  $output = '<div' . drupal_attributes($attributes) . '>' . "\n";
+
+  // If #title is not set, we don't display any label or required marker.
+  if (!isset($element['#title'])) {
+    $element['#title_display'] = 'none';
+  }
+  $prefix = isset($element['#field_prefix']) ? '<span class="field-prefix">' . $element['#field_prefix'] . '</span> ' : '';
+  $suffix = isset($element['#field_suffix']) ? ' <span class="field-suffix">' . $element['#field_suffix'] . '</span>' : '';
+
+  switch ($element['#title_display']) {
+    case 'before':
+    case 'invisible':
+      $output .= ' ' . theme('form_element_label', $variables);
+      $output .= ' ' . $prefix . $element['#children'] . $suffix . "\n";
+      break;
+
+    case 'after':
+      $output .= ' ' . $prefix . $element['#children'] . $suffix;
+      $output .= ' ' . theme('form_element_label', $variables) . "\n";
+      break;
+
+    case 'none':
+    case 'attribute':
+      // Output no label and no required marker, only the children.
+      $output .= ' ' . $prefix . $element['#children'] . $suffix . "\n";
+      break;
+  }
+
+  if (!empty($element['#description'])) {
+    $output .= '<div class="description">' . $element['#description'] . "</div>\n";
+  }
+
+  $output .= "</div>\n";
+
+  return $output;
+}
+
+/**
+ * Returns HTML for a marker for required form elements.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *
+ * @ingroup themeable
+ */
+function theme_form_required_marker($variables) {
+  // This is also used in the installer, pre-database setup.
+  $t = get_t();
+  $attributes = array(
+    'class' => 'form-required',
+    'title' => $t('This field is required.'),
+  );
+  return '<span' . drupal_attributes($attributes) . '>*</span>';
+}
+
+/**
+ * Returns HTML for a form element label and required marker.
+ *
+ * Form element labels include the #title and a #required marker. The label is
+ * associated with the element itself by the element #id. Labels may appear
+ * before or after elements, depending on theme_form_element() and
+ * #title_display.
+ *
+ * This function will not be called for elements with no labels, depending on
+ * #title_display. For elements that have an empty #title and are not required,
+ * this function will output no label (''). For required elements that have an
+ * empty #title, this will output the required marker alone within the label.
+ * The label will use the #id to associate the marker with the field that is
+ * required. That is especially important for screenreader users to know
+ * which field is required.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #required, #title, #id, #value, #description.
+ *
+ * @ingroup themeable
+ */
+function theme_form_element_label($variables) {
+  $element = $variables['element'];
+  // This is also used in the installer, pre-database setup.
+  $t = get_t();
+
+  // If title and required marker are both empty, output no label.
+  if ((!isset($element['#title']) || $element['#title'] === '') && empty($element['#required'])) {
+    return '';
+  }
+
+  // If the element is required, a required marker is appended to the label.
+  $required = !empty($element['#required']) ? theme('form_required_marker', array('element' => $element)) : '';
+
+  $title = filter_xss_admin($element['#title']);
+
+  $attributes = array();
+  // Style the label as class option to display inline with the element.
+  if ($element['#title_display'] == 'after') {
+    $attributes['class'] = 'option';
+  }
+  // Show label only to screen readers to avoid disruption in visual flows.
+  elseif ($element['#title_display'] == 'invisible') {
+    $attributes['class'] = 'element-invisible';
+  }
+
+  if (!empty($element['#id'])) {
+    $attributes['for'] = $element['#id'];
+  }
+
+  // The leading whitespace helps visually separate fields from inline labels.
+  return ' <label' . drupal_attributes($attributes) . '>' . $t('!title !required', array('!title' => $title, '!required' => $required)) . "</label>\n";
+}
+
+/**
+ * Sets a form element's class attribute.
+ *
+ * Adds 'required' and 'error' classes as needed.
+ *
+ * @param $element
+ *   The form element.
+ * @param $name
+ *   Array of new class names to be added.
+ */
+function _form_set_class(&$element, $class = array()) {
+  if (!empty($class)) {
+    if (!isset($element['#attributes']['class'])) {
+      $element['#attributes']['class'] = array();
+    }
+    $element['#attributes']['class'] = array_merge($element['#attributes']['class'], $class);
+  }
+  // This function is invoked from form element theme functions, but the
+  // rendered form element may not necessarily have been processed by
+  // form_builder().
+  if (!empty($element['#required'])) {
+    $element['#attributes']['class'][] = 'required';
+  }
+  if (isset($element['#parents']) && form_get_error($element) !== NULL && !empty($element['#validated'])) {
+    $element['#attributes']['class'][] = 'error';
+  }
+}
+
+/**
+ * Form element validation handler for integer elements.
+ */
+function element_validate_integer($element, &$form_state) {
+  $value = $element['#value'];
+  if ($value !== '' && (!is_numeric($value) || intval($value) != $value)) {
+    form_error($element, t('%name must be an integer.', array('%name' => $element['#title'])));
+  }
+}
+
+/**
+ * Form element validation handler for integer elements that must be positive.
+ */
+function element_validate_integer_positive($element, &$form_state) {
+  $value = $element['#value'];
+  if ($value !== '' && (!is_numeric($value) || intval($value) != $value || $value <= 0)) {
+    form_error($element, t('%name must be a positive integer.', array('%name' => $element['#title'])));
+  }
+}
+
+/**
+ * Form element validation handler for number elements.
+ */
+function element_validate_number($element, &$form_state) {
+  $value = $element['#value'];
+  if ($value != '' && !is_numeric($value)) {
+    form_error($element, t('%name must be a number.', array('%name' => $element['#title'])));
+  }
+}
+
+/**
+ * @} End of "defgroup form_api".
+ */
+
+/**
+ * @defgroup batch Batch operations
+ * @{
+ * Creates and processes batch operations.
+ *
+ * Functions allowing forms processing to be spread out over several page
+ * requests, thus ensuring that the processing does not get interrupted
+ * because of a PHP timeout, while allowing the user to receive feedback
+ * on the progress of the ongoing operations.
+ *
+ * The API is primarily designed to integrate nicely with the Form API
+ * workflow, but can also be used by non-Form API scripts (like update.php)
+ * or even simple page callbacks (which should probably be used sparingly).
+ *
+ * Example:
+ * @code
+ * $batch = array(
+ *   'title' => t('Exporting'),
+ *   'operations' => array(
+ *     array('my_function_1', array($account->uid, 'story')),
+ *     array('my_function_2', array()),
+ *   ),
+ *   'finished' => 'my_finished_callback',
+ *   'file' => 'path_to_file_containing_myfunctions',
+ * );
+ * batch_set($batch);
+ * // Only needed if not inside a form _submit handler.
+ * // Setting redirect in batch_process.
+ * batch_process('node/1');
+ * @endcode
+ *
+ * Note: if the batch 'title', 'init_message', 'progress_message', or
+ * 'error_message' could contain any user input, it is the responsibility of
+ * the code calling batch_set() to sanitize them first with a function like
+ * check_plain() or filter_xss(). Furthermore, if the batch operation
+ * returns any user input in the 'results' or 'message' keys of $context,
+ * it must also sanitize them first.
+ *
+ * Sample batch operations:
+ * @code
+ * // Simple and artificial: load a node of a given type for a given user
+ * function my_function_1($uid, $type, &$context) {
+ *   // The $context array gathers batch context information about the execution (read),
+ *   // as well as 'return values' for the current operation (write)
+ *   // The following keys are provided :
+ *   // 'results' (read / write): The array of results gathered so far by
+ *   //   the batch processing, for the current operation to append its own.
+ *   // 'message' (write): A text message displayed in the progress page.
+ *   // The following keys allow for multi-step operations :
+ *   // 'sandbox' (read / write): An array that can be freely used to
+ *   //   store persistent data between iterations. It is recommended to
+ *   //   use this instead of $_SESSION, which is unsafe if the user
+ *   //   continues browsing in a separate window while the batch is processing.
+ *   // 'finished' (write): A float number between 0 and 1 informing
+ *   //   the processing engine of the completion level for the operation.
+ *   //   1 (or no value explicitly set) means the operation is finished
+ *   //   and the batch processing can continue to the next operation.
+ *
+ *   $node = node_load(array('uid' => $uid, 'type' => $type));
+ *   $context['results'][] = $node->nid . ' : ' . check_plain($node->title);
+ *   $context['message'] = check_plain($node->title);
+ * }
+ *
+ * // More advanced example: multi-step operation - load all nodes, five by five
+ * function my_function_2(&$context) {
+ *   if (empty($context['sandbox'])) {
+ *     $context['sandbox']['progress'] = 0;
+ *     $context['sandbox']['current_node'] = 0;
+ *     $context['sandbox']['max'] = db_query('SELECT COUNT(DISTINCT nid) FROM {node}')->fetchField();
+ *   }
+ *   $limit = 5;
+ *   $result = db_select('node')
+ *     ->fields('node', array('nid'))
+ *     ->condition('nid', $context['sandbox']['current_node'], '>')
+ *     ->orderBy('nid')
+ *     ->range(0, $limit)
+ *     ->execute();
+ *   foreach ($result as $row) {
+ *     $node = node_load($row->nid, NULL, TRUE);
+ *     $context['results'][] = $node->nid . ' : ' . check_plain($node->title);
+ *     $context['sandbox']['progress']++;
+ *     $context['sandbox']['current_node'] = $node->nid;
+ *     $context['message'] = check_plain($node->title);
+ *   }
+ *   if ($context['sandbox']['progress'] != $context['sandbox']['max']) {
+ *     $context['finished'] = $context['sandbox']['progress'] / $context['sandbox']['max'];
+ *   }
+ * }
+ * @endcode
+ *
+ * Sample 'finished' callback:
+ * @code
+ * function batch_test_finished($success, $results, $operations) {
+ *   // The 'success' parameter means no fatal PHP errors were detected. All
+ *   // other error management should be handled using 'results'.
+ *   if ($success) {
+ *     $message = format_plural(count($results), 'One post processed.', '@count posts processed.');
+ *   }
+ *   else {
+ *     $message = t('Finished with an error.');
+ *   }
+ *   drupal_set_message($message);
+ *   // Providing data for the redirected page is done through $_SESSION.
+ *   foreach ($results as $result) {
+ *     $items[] = t('Loaded node %title.', array('%title' => $result));
+ *   }
+ *   $_SESSION['my_batch_results'] = $items;
+ * }
+ * @endcode
+ */
+
+/**
+ * Adds a new batch.
+ *
+ * Batch operations are added as new batch sets. Batch sets are used to spread
+ * processing (primarily, but not exclusively, forms processing) over several
+ * page requests. This helps to ensure that the processing is not interrupted
+ * due to PHP timeouts, while users are still able to receive feedback on the
+ * progress of the ongoing operations. Combining related operations into
+ * distinct batch sets provides clean code independence for each batch set,
+ * ensuring that two or more batches, submitted independently, can be processed
+ * without mutual interference. Each batch set may specify its own set of
+ * operations and results, produce its own UI messages, and trigger its own
+ * 'finished' callback. Batch sets are processed sequentially, with the progress
+ * bar starting afresh for each new set.
+ *
+ * @param $batch_definition
+ *   An associative array defining the batch, with the following elements (all
+ *   are optional except as noted):
+ *   - operations: (required) Array of function calls to be performed.
+ *     Example:
+ *     @code
+ *     array(
+ *       array('my_function_1', array($arg1)),
+ *       array('my_function_2', array($arg2_1, $arg2_2)),
+ *     )
+ *     @endcode
+ *   - title: A safe, translated string to use as the title for the progress
+ *     page. Defaults to t('Processing').
+ *   - init_message: Message displayed while the processing is initialized.
+ *     Defaults to t('Initializing.').
+ *   - progress_message: Message displayed while processing the batch. Available
+ *     placeholders are @current, @remaining, @total, @percentage, @estimate and
+ *     @elapsed. Defaults to t('Completed @current of @total.').
+ *   - error_message: Message displayed if an error occurred while processing
+ *     the batch. Defaults to t('An error has occurred.').
+ *   - finished: Name of a function to be executed after the batch has
+ *     completed. This should be used to perform any result massaging that may
+ *     be needed, and possibly save data in $_SESSION for display after final
+ *     page redirection.
+ *   - file: Path to the file containing the definitions of the 'operations' and
+ *     'finished' functions, for instance if they don't reside in the main
+ *     .module file. The path should be relative to base_path(), and thus should
+ *     be built using drupal_get_path().
+ *   - css: Array of paths to CSS files to be used on the progress page.
+ *   - url_options: options passed to url() when constructing redirect URLs for
+ *     the batch.
+ */
+function batch_set($batch_definition) {
+  if ($batch_definition) {
+    $batch =& batch_get();
+
+    // Initialize the batch if needed.
+    if (empty($batch)) {
+      $batch = array(
+        'sets' => array(),
+        'has_form_submits' => FALSE,
+      );
+    }
+
+    // Base and default properties for the batch set.
+    // Use get_t() to allow batches during installation.
+    $t = get_t();
+    $init = array(
+      'sandbox' => array(),
+      'results' => array(),
+      'success' => FALSE,
+      'start' => 0,
+      'elapsed' => 0,
+    );
+    $defaults = array(
+      'title' => $t('Processing'),
+      'init_message' => $t('Initializing.'),
+      'progress_message' => $t('Completed @current of @total.'),
+      'error_message' => $t('An error has occurred.'),
+      'css' => array(),
+    );
+    $batch_set = $init + $batch_definition + $defaults;
+
+    // Tweak init_message to avoid the bottom of the page flickering down after
+    // init phase.
+    $batch_set['init_message'] .= '<br/>&nbsp;';
+
+    // The non-concurrent workflow of batch execution allows us to save
+    // numberOfItems() queries by handling our own counter.
+    $batch_set['total'] = count($batch_set['operations']);
+    $batch_set['count'] = $batch_set['total'];
+
+    // Add the set to the batch.
+    if (empty($batch['id'])) {
+      // The batch is not running yet. Simply add the new set.
+      $batch['sets'][] = $batch_set;
+    }
+    else {
+      // The set is being added while the batch is running. Insert the new set
+      // right after the current one to ensure execution order, and store its
+      // operations in a queue.
+      $index = $batch['current_set'] + 1;
+      $slice1 = array_slice($batch['sets'], 0, $index);
+      $slice2 = array_slice($batch['sets'], $index);
+      $batch['sets'] = array_merge($slice1, array($batch_set), $slice2);
+      _batch_populate_queue($batch, $index);
+    }
+  }
+}
+
+/**
+ * Processes the batch.
+ *
+ * Unless the batch has been marked with 'progressive' = FALSE, the function
+ * issues a drupal_goto and thus ends page execution.
+ *
+ * This function is generally not needed in form submit handlers;
+ * Form API takes care of batches that were set during form submission.
+ *
+ * @param $redirect
+ *   (optional) Path to redirect to when the batch has finished processing.
+ * @param $url
+ *   (optional - should only be used for separate scripts like update.php)
+ *   URL of the batch processing page.
+ * @param $redirect_callback
+ *   (optional) Specify a function to be called to redirect to the progressive
+ *   processing page. By default drupal_goto() will be used to redirect to a
+ *   page which will do the progressive page. Specifying another function will
+ *   allow the progressive processing to be processed differently.
+ */
+function batch_process($redirect = NULL, $url = 'batch', $redirect_callback = 'drupal_goto') {
+  $batch =& batch_get();
+
+  drupal_theme_initialize();
+
+  if (isset($batch)) {
+    // Add process information
+    $process_info = array(
+      'current_set' => 0,
+      'progressive' => TRUE,
+      'url' => $url,
+      'url_options' => array(),
+      'source_url' => $_GET['q'],
+      'redirect' => $redirect,
+      'theme' => $GLOBALS['theme_key'],
+      'redirect_callback' => $redirect_callback,
+    );
+    $batch += $process_info;
+
+    // The batch is now completely built. Allow other modules to make changes
+    // to the batch so that it is easier to reuse batch processes in other
+    // environments.
+    drupal_alter('batch', $batch);
+
+    // Assign an arbitrary id: don't rely on a serial column in the 'batch'
+    // table, since non-progressive batches skip database storage completely.
+    $batch['id'] = db_next_id();
+
+    // Move operations to a job queue. Non-progressive batches will use a
+    // memory-based queue.
+    foreach ($batch['sets'] as $key => $batch_set) {
+      _batch_populate_queue($batch, $key);
+    }
+
+    // Initiate processing.
+    if ($batch['progressive']) {
+      // Now that we have a batch id, we can generate the redirection link in
+      // the generic error message.
+      $t = get_t();
+      $batch['error_message'] = $t('Please continue to <a href="@error_url">the error page</a>', array('@error_url' => url($url, array('query' => array('id' => $batch['id'], 'op' => 'finished')))));
+
+      // Clear the way for the drupal_goto() redirection to the batch processing
+      // page, by saving and unsetting the 'destination', if there is any.
+      if (isset($_GET['destination'])) {
+        $batch['destination'] = $_GET['destination'];
+        unset($_GET['destination']);
+      }
+
+      // Store the batch.
+      db_insert('batch')
+        ->fields(array(
+          'bid' => $batch['id'],
+          'timestamp' => REQUEST_TIME,
+          'token' => drupal_get_token($batch['id']),
+          'batch' => serialize($batch),
+        ))
+        ->execute();
+
+      // Set the batch number in the session to guarantee that it will stay alive.
+      $_SESSION['batches'][$batch['id']] = TRUE;
+
+      // Redirect for processing.
+      $function = $batch['redirect_callback'];
+      if (function_exists($function)) {
+        $function($batch['url'], array('query' => array('op' => 'start', 'id' => $batch['id'])));
+      }
+    }
+    else {
+      // Non-progressive execution: bypass the whole progressbar workflow
+      // and execute the batch in one pass.
+      require_once DRUPAL_ROOT . '/includes/batch.inc';
+      _batch_process();
+    }
+  }
+}
+
+/**
+ * Retrieves the current batch.
+ */
+function &batch_get() {
+  // Not drupal_static(), because Batch API operates at a lower level than most
+  // use-cases for resetting static variables, and we specifically do not want a
+  // global drupal_static_reset() resetting the batch information. Functions
+  // that are part of the Batch API and need to reset the batch information may
+  // call batch_get() and manipulate the result by reference. Functions that are
+  // not part of the Batch API can also do this, but shouldn't.
+  static $batch = array();
+  return $batch;
+}
+
+/**
+ * Populates a job queue with the operations of a batch set.
+ *
+ * Depending on whether the batch is progressive or not, the BatchQueue or
+ * BatchMemoryQueue handler classes will be used.
+ *
+ * @param $batch
+ *   The batch array.
+ * @param $set_id
+ *   The id of the set to process.
+ *
+ * @return
+ *   The name and class of the queue are added by reference to the batch set.
+ */
+function _batch_populate_queue(&$batch, $set_id) {
+  $batch_set = &$batch['sets'][$set_id];
+
+  if (isset($batch_set['operations'])) {
+    $batch_set += array(
+      'queue' => array(
+        'name' => 'drupal_batch:' . $batch['id'] . ':' . $set_id,
+        'class' => $batch['progressive'] ? 'BatchQueue' : 'BatchMemoryQueue',
+      ),
+    );
+
+    $queue = _batch_queue($batch_set);
+    $queue->createQueue();
+    foreach ($batch_set['operations'] as $operation) {
+      $queue->createItem($operation);
+    }
+
+    unset($batch_set['operations']);
+  }
+}
+
+/**
+ * Returns a queue object for a batch set.
+ *
+ * @param $batch_set
+ *   The batch set.
+ *
+ * @return
+ *   The queue object.
+ */
+function _batch_queue($batch_set) {
+  static $queues;
+
+  // The class autoloader is not available when running update.php, so make
+  // sure the files are manually included.
+  if (!isset($queues)) {
+    $queues = array();
+    require_once DRUPAL_ROOT . '/modules/system/system.queue.inc';
+    require_once DRUPAL_ROOT . '/includes/batch.queue.inc';
+  }
+
+  if (isset($batch_set['queue'])) {
+    $name = $batch_set['queue']['name'];
+    $class = $batch_set['queue']['class'];
+
+    if (!isset($queues[$class][$name])) {
+      $queues[$class][$name] = new $class($name);
+    }
+    return $queues[$class][$name];
+  }
+}
+
+/**
+ * @} End of "defgroup batch".
+ */