form.inc

<?php
/**
 * @defgroup form Form generation
 * @{
 * Functions to enable output of HTML forms and form elements.
 *
 * Drupal uses these functions to achieve consistency in its form presentation,
 * while at the same time simplifying code and reducing the amount of HTML that
 * must be explicitly generated by modules.
 */

/**
 * Check if the key is a property.
 */
function element_property($key) {
  return $key{0} == '#';
}

function element_properties($element) {
  return array_filter(array_keys((array) $element), 'element_property');
}

/**
 * Check if the key is a child.
 */
function element_child($key) {
  return $key{0} != '#';
}

function element_children($element) {
  return array_filter(array_keys((array) $element), 'element_child');
}

/**
 * Processes a form array, and produces the HTML output of a form.
 * If there is input in the $_POST['edit'] variable, this function
 * will attempt to validate it, using <code>drupal_validate_form</code>,
 * and then execute the form using <code>drupal_execute_form</code>.
 *
 * @param $form_id
 *   A unique string identifying the form. Allows each form to be themed.
 * @param $form
 *   An associative array containing the structure of the form.
 * @param $callback
 *   An optional callback that will be used in addition to the form_id.
 *
 */
function drupal_get_form($form_id, &$form, $callback = NULL) {
  global $form_values, $form_execute;
  $form_values = array();
  $form_execute = FALSE;

  $form['#type'] = 'form';
  if (isset($form['#token'])) {
    $form['form_token'] = array('#type' => 'hidden', '#value' => md5($_SERVER['REMOTE_ADDR'] . $form['#token'] . variable_get('drupal_private_key',
'')));
  }
  $form['form_id'] = array('#type' => 'hidden', '#default_value' => $form_id);

  $form = array_merge(_element_info('form'), $form);

  foreach (module_implements('form_alter') as $module) {
    $function = $module .'_form_alter';
    $function($form);
  }

  $function = $form_id . '_form_alter';
  if (function_exists($function)) {
    $function($form);
  }

  $form = _form_builder($form);

  if (!empty($_POST['edit']) && (($form_values['form_id'] == $form_id) || ($form_values['form_id'] == $callback))) {
    drupal_validate_form($form_id, $form, $callback);
    if ($form_execute && !form_get_errors()) {
      drupal_execute_form($form_id, $form, $callback);
    }
  }

  if (function_exists('theme_' . $form_id)) {
    $form['#theme'] = $form_id;
  }
  elseif (function_exists('theme_' . $callback)) {
    $form['#theme'] = $callback;
  }
  return form_render($form);
}

function drupal_validate_form($form_id, &$form, $callback = NULL) {
  global $form_values;

  if (isset($form['#token'])) {
    if ($form_values['form_token'] != md5($_SERVER['REMOTE_ADDR'] . $form['#token'] . variable_get('drupal_private_key', ''))) {
      // setting this error will cause the form to fail validation
      form_set_error('form_token', t('Validation error, please try again.  If this error persists, please contact the site administrator.'));
    }
  }

  foreach (module_implements('form_validate_alter') as $module) {
    $function = $module .'_form_validate_alter';
    $function($form_id, $form_values);
  }

  _form_validate($form);

  if (function_exists($form_id . '_validate')) {
    call_user_func($form_id . '_validate', $form_id, $form_values);
  }
  if (function_exists($callback . '_validate')) {
    call_user_func($callback . '_validate', $form_id, $form_values);
  }
}

function drupal_execute_form($form_id, $form, $callback = NULL) {
  global $form_values;
  foreach (module_implements('form_execute_alter') as $module) {
    $function = $module .'_form_execute_alter';
    $function($form_id, $form_values);
  }

  if (function_exists($form_id . '_execute')) {
    call_user_func($form_id . '_execute', $form_id, $form_values);
  }
  elseif (function_exists($callback . '_execute')) {
    call_user_func($callback . '_execute', $form_id, $form_values);
  }
}

function _form_validate($elements) {

  // Recurse through all children.
  foreach (element_children($elements) as $key) {
    if (isset($elements[$key]) && $elements[$key]) {
      _form_validate($elements[$key]);
    }
  }

  /* Validate the current input */
  if (!$elements['#validated'] && $elements['#input']) {
    if ($elements['#required'] && !isset($elements['#value'])) {
        form_error($elements, t('%name field is required', array('%name' => $elements['#title'])));
    }
    if ($elements['#valid']) {
      if (is_array($elements['#valid'])) {
        foreach ($elements['#valid'] as $key => $valid) {
          $args = is_array($elements['#validation_arguments'][$key]) ? $elements['#validation_arguments'][$key] : array();
          if (function_exists($valid . '_valid'))  {
            call_user_func_array($valid . '_valid', array_merge(array($elements), $args));
          }
        }
      }
      else {
        $args = is_array($elements['#validation_arguments']) ? $elements['#validation_arguments'] : array();
        if (function_exists($elements['#valid'] . '_valid'))  {
          call_user_func_array($elements['#valid'] . '_valid', array_merge(array($elements), $args));
        }
      }
    }
    $elements['#validated'] = TRUE;
  }
}

/**
 * File an error against a form element. If the name of the element is
 * edit[foo][bar] then you may pass either foo or foo][bar as $name
 * foo will set an error for all its children.
 */
function form_set_error($name = NULL, $message = NULL) {
  static $form = array();
  if (isset($name) && !isset($form[$name])) {
    $form[$name] = $message;
    drupal_set_message($message, 'error');
  }
  return $form;
}

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

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

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

/**
 * Adds some required properties to each form element, which are used internally in the form api.
 * This function also automatically assigns the value property from the $edit array, provided the
 * element doesn't already have an assigned value.
 */
function _form_builder($form) {
  global $form_values;
  global $form_execute;
  /* Use element defaults */
  if ((!empty($form['#type'])) && ($info = _element_info($form['#type']))) {
    $form += $info;
  }

  if ($form['#input']) {
    $form['#name'] = ($form['#name']) ? $form['#name'] : 'edit[' . implode('][', $form['#parents']) . ']';
    $form['#id'] =  ($form['#id']) ? $form['#id'] : 'edit-' . implode('-', $form['#parents']);

    $posted = isset($_POST['edit']);
    $edit = $posted ? $_POST['edit'] : array();
    $ref =& $form_values;
    foreach ($form['#parents'] as $parent) {
      $edit = isset($edit[$parent]) ? $edit[$parent] : NULL;
      $ref =& $ref[$parent];
    }
    if (!isset($form['#value'])) {
      $form['#value'] = ($posted && isset($edit)) ? $edit : $form['#default_value'];
    }
    if (isset($form['#execute'])) {
      if ($_POST[$form['#name']] == $form['#value']) {
        $form_execute = $form_execute || $form['#execute'];
      }
    }

    $ref = $form['#value'];
  }

  // Allow for elements to expand to multiple elements. Radios, checkboxes and files for instance.
  if (function_exists($form['#process']) && !$form['#processed']) {
    $form = call_user_func($form['#process'], $form);
    $form['#processed'] = TRUE;
  }

  // Recurse through all child elements.
  $count  = 0;
  foreach (element_children($form) as $key) {
    // don't squash an existing tree value
    $form[$key]['#tree'] = (isset($form[$key]['#tree'])) ? $form[$key]['#tree'] : $form['#tree'];

    if ($form[$key]['#tree']) {
      if (!$form['#tree']) {
        // begin tree
        $parents = array($key);
      }
      else {
        //continue tree
        $parents = (array) $form['#parents'];
        array_push($parents, $key);
      }
    }
    else {
      // no tree
      $parents = array($key);
    }

    // don't squash existing parents value
    $form[$key]['#parents'] = (isset($form[$key]['#parents'])) ? $form[$key]['#parents'] : $parents;

    # Assign a decimal placeholder weight, to preserve original array order
    $form[$key]['#weight'] = $form[$key]['#weight'] ? $form[$key]['#weight'] : $count/1000;
    $form[$key] = _form_builder($form[$key]);
    $count++;
  }

  if (function_exists($form['#post_process']) && !$form['#post_processed']) {
    $form = call_user_func($form['#post_process'], $form_id, $form, $form_values, $form['#parents']);
    $form['#post_processed'] = TRUE;
  }

  return $form;
}

/**
 * Renders a HTML form given an form tree.  Recursively iterates over each of
 * each of the form elements generating HTML code.  This function is usually
 * called from within a theme.  To render a form from within a module, use
 * <code>drupal_get_form()</code>.
 *
 * @param $elements
 *   The form tree describing the form.
 * @return
 *   The rendered HTML form.
 */
function form_render(&$elements) {
  $content = '';
  if (is_array($elements)) {
    uasort($elements, "_form_sort");
  }

  if (!$elements['#children']) {
    /* render all the children using a theme function */
    if ($elements['#theme'] && !$elements['#theme_used']) {
      $elements['#theme_used'] = TRUE;
      $previous_type = $elements['#type'];
      $elements['#type'] = 'markup';
      $content = theme($elements['#theme'], $elements);
      $elements['#type'] = $previous_type;
    }
    /* render each of the children using form_render and concatenate them */
    if (!$content) {
      foreach (element_children($elements) as $key) {
        $content .= form_render($elements[$key]);
      }
    }
  }
  if ($content) {
    $elements['#children'] = $content;
  }

  /* Call the form element renderer */
  if (!$elements['#printed']) {
    $content = theme(($elements['#type']) ? $elements['#type']: 'markup', $elements);
    $elements['#printed'] = TRUE;
  }

  if ($content) {
    return $elements['#prefix'] . $content . $elements['#suffix'];
  }
}

/**
 * Function used by uasort in form render to sort form via weight.
 */
function _form_sort($a, $b) {
  if ($a['#weight'] == $b['#weight']) {
    return 0;
  }
  return ($a['#weight'] < $b['#weight']) ? -1 : 1;
}

/**
 * Retrieve the default properties for the defined element type.
 */
function _element_info($type, $refresh = null) {
  static $cache;

  $parents = array();
  $basic_defaults = array(
    '#description' => NULL,
    '#attributes' => array(),
    '#required' => FALSE,
    '#tree' => FALSE,
    '#parents' => $parents
  );
  if ($refresh || !is_array($cache)) {
    $cache = array();
    foreach (module_implements('elements') as $module) {
      $elements = module_invoke($module, 'elements');
      if (is_array($elements)) {
        $cache = array_merge($cache, $elements);
      }
    }
    if (sizeof($cache)) {
      foreach ($cache as $element_type => $info) {
        $cache[$element_type] = array_merge($basic_defaults, $info);
      }
    }
  }

  return $cache[$type];
}

/**
 * Format a dropdown menu or scrolling selection box.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : title, value, options, description, extra, multiple, required
 * @return
 *   A themed HTML string representing the 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 $options format.
 */
function theme_select($element) {
  $select = '';
  foreach ($element['#options'] as $key => $choice) {
    if (is_array($choice)) {
      $select .= '<optgroup label="'. $key .'">';
      foreach ($choice as $key => $choice) {
        $select .= '<option value="'. $key .'"'. (is_array($element['#value']) ? (in_array($key, $element['#value']) ? ' selected="selected"' : '') : ($element['#value'] == $key ? ' selected="selected"' : '')) .'>'. check_plain($choice) .'</option>';
      }
      $select .= '</optgroup>';
    }
    else {
      $select .= '<option value="'. $key .'"'. (is_array($element['#value']) ? (in_array($key, $element['#value']) ? ' selected="selected"' : '') : ($element['#value'] == $key ? ' selected="selected"' : '')) .'>'. check_plain($choice) .'</option>';
    }
  }
  return theme('form_element', $element['#title'], '<select name="'. $element['#name'] .''. ($element['#multiple'] ? '[]' : '') .'"'. ($element['#multiple'] ? ' multiple="multiple" ' : '') . drupal_attributes($element['#attributes']) .' id="' . $element['#id'] .'">'. $select .'</select>', $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
}

/**
 * Format a group of form items.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : attributes, title, description, children, collapsible, collapsed
 * @return
 *   A themed HTML string representing the form item group.
 */
function theme_fieldset($element) {
  if ($element['#collapsible']) {
    drupal_add_js('misc/collapse.js');

    $element['#attributes']['class'] .= ' collapsible';
    if ($element['#collapsed']) {
     $element['#attributes']['class'] .= ' collapsed';
    }
  }

  return '<fieldset' . drupal_attributes($element['#attributes']) .'>' . ($element['#title'] ? '<legend>'. $element['#title'] .'</legend>' : '') . $element['#children'] . $element['#value'] . ($element['#description'] ? '<div class="description">'. $element['#description'] .'</div>' : '') . "</fieldset>\n";

}


/**
 * Format a radio button.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : required, return_value, value, attributes, title, description
 * @return
 *   A themed HTML string representing the form item group.
 */
function theme_radio($element) {
  $output = '<input type="radio" ';
  $output .= 'class="'. _form_get_class('form-radio', $element['#required'], form_get_error($element)) .'" ';
  $output .= 'name="' . $element['#name'] .'" ';
  $output .= 'value="'. $element['#return_value'] .'" ';
  $output .= ($element['#value'] == $element['#return_value']) ? ' checked="checked" ' : ' ';
  $output .= drupal_attributes($element['#attributes']) .' />';
  if (!is_null($element['#title'])) {
    $output = '<label class="option">'. $output .' '. $element['#title'] .'</label>';
  }
  return theme('form_element', NULL, $output, $element['#description'], $element['#name'], $element['#required'], form_get_error($element));
}

/**
 * Format a set of radio buttons.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : title, value, options, description, required and attributes.
 * @return
 *   A themed HTML string representing the radio button set.
 */
function theme_radios($element) {
  if ($element['#title'] || $element['#description']) {
    return theme('form_element', $element['#title'], $element['#children'], $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
  }
  else {
    return $element['#children'];
  }
}

/**
 * Format a set of radio buttons.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : title, value, options, description, required and attributes.
 * @return
 *   A themed HTML string representing the radio button set.
 */
function theme_date($element) {
  $output = '<div class="container-inline">' . $element['#children'] . '</div>';
  return theme('form_element', $element['#title'], $output, $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
}

/**
 * Roll out a single checkbox element to a list of checkboxes, using the options array as index.
 */
function expand_date($element) {
  // Default to current date
  if (!isset($element['#value'])) {
    $element['#value'] = array('day' => format_date(time(), 'custom', 'j'),
                            'month' => format_date(time(), 'custom', 'n'),
                            'year' => format_date(time(), 'custom', 'Y'));
  }

  // Determine the order of day, month, year in the site's chosen date format.
  $format = variable_get('date_format_short', 'm/d/Y');
  $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));
        break;
      case 'month':
        $options = drupal_map_assoc(range(1, 12), '_profile_map_month');
        break;
      case 'year':
        $options = drupal_map_assoc(range(1900, 2050));
        break;
    }
    $element[$type] = array('#type' => 'select', '#value' => $element['#value'][$type], '#attributes' => $element['#attributes'], '#parents' => $element['#parents'], '#options' => $options,  '#tree' => TRUE);
  }

  return $element;
}


/**
 * Roll out a single adios element
 * to a list of radios, using the options array as index.
 */
function expand_radios($element) {
  if (count($element['#options']) > 0) {
    foreach ($element['#options'] as $key => $choice) {
      if (!$element[$key]) {
        $element[$key] = array('#type' => 'radio', '#title' => $choice, '#return_value' => $key, '#default_value' => $element['#default_value'], '#attributes' => $element['#attributes'], '#parents' => $element['#parents'], '#spawned' => TRUE);
      }
    }
  }
  return $element;
}


/**
 * Format a form item.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used :  title, value, description, required, error
 * @return
 *   A themed HTML string representing the form item.
 */
function theme_item($element) {
  return theme('form_element', $element['#title'], $element['#value'] . $element['#children'], $element['#description'], $element['#id'], $element['#required'], $element['#error']);
}


/**
 * Format a checkbox.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used :  title, value, return_value, description, required
 * @return
 *   A themed HTML string representing the checkbox.
 */
function theme_checkbox($element) {
  $checkbox = '<input ';
  $checkbox .= 'type="checkbox" ';
  $checkbox .= 'class="'. _form_get_class('form-checkbox', $element['#required'], form_get_error($element)) . '" ';
  $checkbox .= 'name="'. $element['#name'] .'" ';
  $checkbox .= 'id="'. $element['#id'].'" ' ;
  $checkbox .= 'value="'. $element['#return_value'] .'" ';
  $checkbox .= ($element['#value'] == $element['#return_value']) ? ' checked="checked" ' : ' ';
  $checkbox .= drupal_attributes($element['#attributes']) . ' />';

  if (!is_null($element['#title'])) {
    $checkbox = '<label class="option">'. $checkbox .' '. $element['#title'] .'</label>';
  }

  return theme('form_element', NULL, $checkbox, $element['#description'], $element['#name'], $element['#required'], form_get_error($element));
}

/**
 * Format a set of checkboxes.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 * @return
 *   A themed HTML string representing the checkbox set.
 */
function theme_checkboxes($element) {
  if ($element['#title'] || $element['#description']) {
    return theme('form_element', $element['#title'], $element['#children'], $element['#description'], 'edit-'. $element['#name'], $element['#required'], form_get_error($element));
  }
  else {
    return $element['#children'];
  }
}

function expand_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) {
      $element['#default_value'] = array();
    }
    foreach ($element['#options'] as $key => $choice) {
      if (!isset($element[$key])) {
        $element[$key] = array('#type' => 'checkbox', '#processed' => TRUE, '#title' => $choice, '#default_value' => in_array($key, $value), '#attributes' => $element['#attributes']);
      }
    }
  }
  return $element;
}


function theme_submit($element) {
  return theme('button', $element);
}

function theme_button($element) {
  return '<input type="submit" class="form-'. $element['#button_type'] .'" name="'. $element['#name'] .'" value="'. check_plain($element['#value']) .'" '. drupal_attributes($element['#attributes']) ." />\n";
}

/**
 * Format a hidden form field.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used :  value, edit
 * @return
 *   A themed HTML string representing the hidden form field.
 */
function theme_hidden($element) {
  return '<input type="hidden" name="'. $element['#name'] . '" id="' . $element['#id'] . '" value="'. check_plain($element['#value']) ."\" " . drupal_attributes($element['#attributes']) ." />\n";
}

/**
 * Format a textfield.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used :  title, value, description, size, maxlength, required, attributes autocomplete_path
 * @return
 *   A themed HTML string representing the textfield.
 */
function theme_textfield($element) {
  $size = $element['#size'] ? ' size="' . $element['#size'] . '"' : '';
  if ($element['#autocomplete_path']) {
    drupal_add_js('misc/autocomplete.js');
    $class = ' form-autocomplete';
    $extra =  '<input class="autocomplete" type="hidden" id="'. $element['#id'] .'-autocomplete" value="'. check_url(url($element['#autocomplete_path'], NULL, NULL, TRUE)) .'" disabled="disabled" />';
  }

  $output = '<input type="text" maxlength="'. $element['#maxlength'] .'" class="'. _form_get_class("form-text$class", $element['#required'], form_get_error($element)) .'" name="'. $element['#name'] .'" id="'. $element['#id'] .'" '. $size .' value="'. check_plain($element['#value']) .'"'. drupal_attributes($element['#attributes']) .' />';
  return theme('form_element', $element['#title'], $output, $element['#description'], $element['#id'], $element['#required'], form_get_error($element)). $extra;
}

/**
 * Format a form.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : action, method, attributes, children
 * @return
 *   A themed HTML string representing the form.
 */
function theme_form($element) {
  // Anonymous div to satisfy XHTML compliancy.
  $action = $element['#action'] ? 'action="' . check_url($element['#action']) . '" ' : '';
  return '<form '. $action . ' method="'. $element['#method'] .'" '. drupal_attributes($element['#attributes']) .">\n<div>". $element['#children'] ."\n</div></form>\n";
}


/**
 * Format a textarea.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : title, value, description, rows, cols, required, attributes
 * @return
 *   A themed HTML string representing the textarea.
 */
function theme_textarea($element) {
  $cols = $element['#cols'] ? ' cols="'. $element['#cols'] .'"' : '';

  return theme('form_element', $element['#title'], '<textarea'. $cols .' rows="'. $element['#rows'] .'" name="'. $element['#name'] .'" id="' . $element['#id'] .'" class="'. _form_get_class('textarea', $element['#required'], form_get_error($element)) .'"'. drupal_attributes($element['#attributes']) .'>'. check_plain($element['#value']) .'</textarea>', $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
}

/**
 * Format HTML markup for use in forms.
 *
 * This is used in more advanced forms, such as theme selection and filter format.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used : prefix, value, children and suffix.
 * @return
 *   A themed HTML string representing the HTML markup.
 */

function theme_markup($element) {
  return $element['#value'] . $element['#children'];
}



/**
* Format a password field.
*
* @param $element
*   An associative array containing the properties of the element.
*   Properties used :  title, value, description, size, maxlength, required, attributes
* @return
*   A themed HTML string representing the form.
*/
function theme_password($element) {
  $size = $element['#size'] ? ' size="'. $element['#size'] .'" ' : '';

  $output = '<input type="password" maxlength="'. $element['#maxlength'] .'" class="'. _form_get_class("form-text $class", $element['#required'], form_get_error($element)) .'" name="'. $element['#name'] .'" id="'. $element['#id'] .'" '. $size . drupal_attributes($element['#attributes']) .' />';

  return theme('form_element', $element['#title'], $output, $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
}

/**
 * Format a weight selection menu.
 *
 * @param $element
 *   An associative array containing the properties of the element.
 *   Properties used :  title, delta, description
 * @return
 *   A themed HTML string representing the form.
 */
function theme_weight($element) {
  for ($n = (-1 * $element['#delta']); $n <= $element['#delta']; $n++) {
    $weights[$n] = $n;
  }
  $element['#options'] = $weights;
  $element['#type'] = 'select';

  return form_render($element);
}

/**
 * Format a file upload field.
 *
 * @param $title
 *   The label for the file upload field.
 * @param $name
 *   The internal name used to refer to the field.
 * @param $size
 *   A measure of the visible size of the field (passed directly to HTML).
 * @param $description
 *   Explanatory text to display after the form item.
 * @param $required
 *   Whether the user must upload a file to the field.
 * @return
 *   A themed HTML string representing the field.
 *
 * For assistance with handling the uploaded file correctly, see the API
 * provided by file.inc.
 */
function theme_file($element) {
  return theme('form_element', $element['#title'], '<input type="file" class="'. _form_get_class('form-file', $element['#required'], form_get_error($element)) .'" name="'. $element['#name'] .'" id="'. form_clean_id($element['#id']) .'" size="'. $element['#size'] ."\" />\n", $element['#description'], $element['#id'], $element['#required'], form_get_error($element));
}
function _form_get_class($name, $required, $error) {
  return $name. ($required ? ' required' : '') . ($error ? ' error' : '');
}

/**
 * Remove invalid characters from an HTML ID attribute string
 *
 * @param $id
 *   The ID to clean
 * @return
 *   The cleaned ID
 */
function form_clean_id($id = NULL) {
  $id = str_replace('][', '-', $id);
  return $id;
}

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