handlers.inc

<?php
// $Id$
/**
 * @file handlers.inc
 * Defines the various handler objects to help build and display views.
 */

/**
 * Instantiate and construct a new handler
 */
function _views_create_handler($definition, $type = 'handler') {
//  vpr('Instantiating handler ' . $definition['handler']);
  if (empty($definition['handler'])) {
    return;
  }

  if (!class_exists($definition['handler']) && !views_include_handler($definition, $type)) {
    return;
  }

  $handler = new $definition['handler'];
  $handler->set_definition($definition);
  // let the handler have something like a constructor.
  $handler->construct();

  return $handler;
}

/**
 * Attempt to find the include file for a given handler from its definition.
 *
 * This will also attempt to include all parents, though we're maxing the
 * parent chain to 10 to prevent infinite loops.
 */
function views_include_handler($definition, $type, $count = 0) {
  // Do not proceed if the class already exists.
  if (isset($definition['handler']) && class_exists($definition['handler'])) {
    return TRUE;
  }

  // simple infinite loop prevention.
  if ($count > 10) {
    vpr(t('Handler @handler include tried to loop infinitely!', array('@handler' => $definition['handler'])));
    return FALSE;
  }

  if (!isset($definition['path'])) {
    if ($type == 'handler') {
      $definition += views_fetch_handler_data($definition['handler']);
    }
    else {
      $definition += views_fetch_plugin_data($type, $definition['handler']);
    }
  }

  if (!empty($definition['parent'])) {
    if ($type == 'handler') {
      $parent = views_fetch_handler_data($definition['parent']);
    }
    else {
      $parent = views_fetch_plugin_data($type, $definition['parent']);
    }

    if ($parent) {
      $rc = views_include_handler($parent, $type, $count + 1);
      // If the parent chain cannot be included, don't try; this will
      // help alleviate problems with modules with cross dependencies.
      if (!$rc) {
        return FALSE;
      }
    }
  }

  if (isset($definition['path']) && $definition['file']) {
    $filename = './' . $definition['path'] . '/' . $definition['file'];
    if (file_exists($filename)) {
      require_once $filename;
    }
  }

  return class_exists($definition['handler']);
}

/**
 * Prepare a handler's data by checking defaults and such.
 */
function _views_prepare_handler($definition, $data, $field) {
  foreach (array('group', 'title', 'title short', 'help', 'real field') as $key) {
    if (!isset($definition[$key])) {
      // First check the field level
      if (!empty($data[$field][$key])) {
        $definition[$key] = $data[$field][$key];
      }
      // Then if that doesn't work, check the table level
      else if (!empty($data['table'][$key])) {
        $definition[$key] = $data['table'][$key];
      }
    }
  }

  return _views_create_handler($definition);
}

/**
 * Fetch the handler data from cache.
 */
function views_fetch_handler_data($handler = NULL) {
  static $cache = NULL;
  if (!isset($cache)) {
    $start = views_microtime();

    $cache = views_discover_handlers();

    vpr('Views handlers build time: ' . (views_microtime() - $start) * 1000 . ' ms');
  }

  if (!$handler) {
    return $cache;
  }
  else if (isset($cache[$handler])) {
    return $cache[$handler];
  }

  // Return an empty array if there is no match.
  return array();
}

/**
 * Builds and return a list of all handlers available in the system.
 *
 * @return Nested array of handlers
 */
function views_discover_handlers() {
  $cache = array();
  // Get handlers from all modules.
  foreach (module_implements('views_handlers') as $module) {
    $function = $module . '_views_handlers';
    $result = $function();
    if (!is_array($result)) {
      continue;
    }

    $module_dir = isset($result['info']['module']) ? $result['info']['module'] : $module;
    $path = isset($result['info']['path']) ? $result['info']['path'] : drupal_get_path('module', $module_dir);

    foreach ($result['handlers'] as $handler => $def) {
      if (!isset($def['module'])) {
        $def['module'] = $module_dir;
      }
      if (!isset($def['path'])) {
        $def['path'] = $path;
      }
      if (!isset($def['file'])) {
        $def['file'] = "$handler.inc";
      }
      if (!isset($def['handler'])) {
        $def['handler'] = $handler;
      }
      // merge the new data in
      $cache[$handler] = $def;
    }
  }
  return $cache;
}

/**
 * Fetch a handler to join one table to a primary table from the data cache
 */
function views_get_table_join($table, $base_table) {
  $data = views_fetch_data($table);
  if (isset($data['table']['join'][$base_table])) {
    $h = $data['table']['join'][$base_table];
    if (!empty($h['handler']) && class_exists($h['handler'])) {
      $handler = new $h['handler'];
    }
    else {
      $handler = new views_join();
    }

    // Fill in some easy defaults
    $handler->definition = $h;
    if (empty($handler->definition['table'])) {
      $handler->definition['table'] = $table;
    }
    // If this is empty, it's a direct link.
    if (empty($handler->definition['left_table'])) {
      $handler->definition['left_table'] = $base_table;
    }

    if (isset($h['arguments'])) {
      call_user_func_array(array(&$handler, 'construct'), $h['arguments']);
    }
    else {
      $handler->construct();
    }

    return $handler;
  }
  // DEBUG -- identify missing handlers
  vpr("Missing join: $table $base_table");
}

/**
 * Base handler, from which all the other handlers are derived.
 * It creates a common interface to create consistency amongst
 * handlers and data.
 *
 * This class would be abstract in PHP5, but PHP4 doesn't understand that.
 *
 * Definition terms:
 * - table: The actual table this uses; only specify if different from
 *          the table this is attached to.
 * - real field: The actual field this uses; only specify if different from
 *               the field this item is attached to.
 * - group: A text string representing the 'group' this item is attached to,
 *          for display in the UI. Examples: "Node", "Taxonomy", "Comment",
 *          "User", etc. This may be inherited from the parent definition or
 *          the 'table' definition.
 * - title: The title for this handler in the UI. This may be inherited from
 *          the parent definition or the 'table' definition.
 * - help: A more informative string to give to the user to explain what this
 *         field/handler is or does.
 * - access callback: If this field should have access control, this could
 *                    be a function to use. 'user_access' is a common
 *                    function to use here. If not specified, no access
 *                    control is provided.
 * - access arguments: An array of arguments for the access callback.
 */
class views_handler extends views_object {
  /**
   * init the handler with necessary data.
   * @param $view
   *   The $view object this handler is attached to.
   * @param $options
   *   The item from the database; the actual contents of this will vary
   *   based upon the type of handler.
   */
  function init(&$view, $options) {
    $this->view = &$view;
    $this->unpack_options($this->options, $options);

    // This exist on most handlers, but not all. So they are still optional.
    if (isset($options['table'])) {
      $this->table = $options['table'];
    }

    if (isset($this->definition['real field'])) {
      $this->real_field = $this->definition['real field'];
    }

    if (isset($this->definition['field'])) {
      $this->real_field = $this->definition['field'];
    }

    if (isset($options['field'])) {
      $this->field = $options['field'];
      if (!isset($this->real_field)) {
        $this->real_field = $options['field'];
      }
    }

    $this->query = &$view->query;
  }

  /**
   * Return a string representing this handler's name in the UI.
   */
  function ui_name($short = FALSE) {
    $title = ($short && isset($this->definition['title short'])) ? $this->definition['title short'] : $this->definition['title'];
    return t('!group: !title', array('!group' => $this->definition['group'], '!title' => $title));
  }

  /**
   * Provide a form for setting options.
   */
  function options_form(&$form, &$form_state) { }

  /**
   * Validate the options form.
   */
  function options_validate($form, &$form_state) { }

  /**
   * Perform any necessary changes to the form values prior to storage.
   * There is no need for this function to actually store the data.
   */
  function options_submit($form, &$form_state) { }

  /**
   * If a handler has 'extra options' it will get a little settings widget and
   * another form called extra_options.
   */
  function has_extra_options() { return FALSE; }

  /**
   * Provide defaults for the handler.
   */
  function extra_options(&$option) { }

  /**
   * Provide a form for setting options.
   */
  function extra_options_form(&$form, &$form_state) { }

  /**
   * Validate the options form.
   */
  function extra_options_validate($form, &$form_state) { }

  /**
   * Perform any necessary changes to the form values prior to storage.
   * There is no need for this function to actually store the data.
   */
  function extra_options_submit($form, &$form_state) { }
  
  /**
   * Determine if a handler can be exposed.
   */
  function can_expose() { return FALSE; }
  
  /**
   * Set new exposed option defaults when exposed setting is flipped
   * on.
   */
  function expose_options() { }
  
  /**
   * Get information about the exposed form for the form renderer.
   */
  function exposed_info() { }
  
  /**
   * Render our chunk of the exposed handler form when selecting
   */
  function exposed_form(&$form, &$form_state) { }

  /**
   * Validate the exposed handler form
   */
  function exposed_validate(&$form, &$form_state) { }

  /**
   * Submit the exposed handler form
   */
  function exposed_submit(&$form, &$form_state) { }

  /**
   * Overridable form for exposed handler options.
   *
   * If overridden, it is best to call the parent or re-implement
   * the stuff here.
   *
   * Many handlers will need to override this in order to provide options
   * that are nicely tailored to the given filter.
   */
  function expose_form(&$form, &$form_state) {
    $form['expose']['start_left'] = array(
      '#value' => '<div class="views-left-50">',
    );

    $this->expose_form_left($form, $form_state);

    $form['expose']['end_left'] = array(
      '#value' => '</div>',
    );

    $form['expose']['start_checkboxes'] = array(
      '#value' => '<div class="form-checkboxes views-left-40 clear-block">',
    );

    $this->expose_form_right($form, $form_state);

    $form['expose']['end_checkboxes'] = array(
      '#value' => '</div>',
    );
  }

  function expose_form_left(&$form, &$form_state) { }
  
  function expose_form_right(&$form, &$form_state){ }

  /**
   * Validate the options form.
   */
  function expose_validate($form, &$form_state) { }

  /**
   * Perform any necessary changes to the form exposes prior to storage.
   * There is no need for this function to actually store the data.
   */
  function expose_submit($form, &$form_state) { }
 
    /**
   * Shortcut to display the expose/hide button.
   */
  function show_expose_button(&$form, &$form_state) {
    $form['expose_button'] = array(
      '#prefix' => '<div class="views-expose clear-block">',
      '#suffix' => '</div>',
    );
    if (empty($this->options['exposed'])) {
      $form['expose_button']['button'] = array(
        '#type' => 'submit',
        '#value' => t('Expose'),
        '#submit' => array('views_ui_config_item_form_expose'),
      );
      $form['expose_button']['markup'] = array(
        '#prefix' => '<div class="description">',
        '#value' => t('This item is currently not exposed. If you <strong>expose</strong> it, users will be able to change the filter as they view it.'),
        '#suffix' => '</div>',
      );
    }
    else {
      $form['expose_button']['button'] = array(
        '#type' => 'submit',
        '#value' => t('Hide'),
        '#submit' => array('views_ui_config_item_form_expose'),
      );
      $form['expose_button']['markup'] = array(
        '#prefix' => '<div class="description">',
        '#value' => t('This item is currently exposed. If you <strong>hide</strong> it, users will not be able to change the filter as they view it.'),
        '#suffix' => '</div>',
      );
    }
  }
    
  /**
   * Shortcut to display the exposed options form.
   */
  function show_expose_form(&$form, &$form_state) {
    if (empty($this->options['exposed'])) {
      return;
    }

    $form['expose'] = array(
      '#prefix' => '<div class="views-expose-options clear-block">',
      '#suffix' => '</div>',
    );
    $this->expose_form($form, $form_state);

    // When we click the expose button, we add new gadgets to the form but they
    // have no data in $_POST so their defaults get wiped out. This prevents
    // these defaults from getting wiped out. This setting will only be TRUE
    // during a 2nd pass rerender.
    if (!empty($form_state['force_expose_options'])) {
      foreach (element_children($form['expose']) as $id) {
        if (isset($form['expose'][$id]['#default_value']) && !isset($form['expose'][$id]['#value'])) {
          $form['expose'][$id]['#value'] = $form['expose'][$id]['#default_value'];
        }
      }
    }
  }
  
 /**
  * Check whether current user has access to this handler.
  *
  * @return boolean
  */
  function access() {
    if (isset($this->definition['access callback']) && function_exists($this->definition['access callback'])) {
      if (isset($this->definition['access arguments']) && is_array($this->definition['access arguments'])) {
        return call_user_func_array($this->definition['access callback'], $this->definition['access arguments']);
      }
      return $this->definition['access callback']();
    }

    return TRUE;
  }

  /**
   * Run before the view is built.
   *
   * This gives all the handlers some time to set up before any handler has
   * been fully run.
   */
  function pre_query() { }

  /**
   * Called just prior to query(), this lets a handler set up any relationship
   * it needs.
   */
  function set_relationship() {
    // Ensure this gets set to something.
    $this->relationship = NULL;

    // Don't process non-existant relationships.
    if (empty($this->options['relationship']) || $this->options['relationship'] == 'none') {
      return;
    }

    $relationship = $this->options['relationship'];

    // Ignore missing/broken relationships.
    if (empty($this->view->relationship[$relationship])) {
      return;
    }

    // Check to see if the relationship has already processed. If not, then we
    // cannot process it.
    if (empty($this->view->relationship[$relationship]->alias)) {
      return;
    }

    // Finally!
    $this->relationship = $this->view->relationship[$relationship]->alias;
  }

  /**
   * Add this handler into the query.
   *
   * If we were using PHP5, this would be abstract.
   */
  function query() { }

  /**
   * Ensure the main table for this handler is in the query. This is used
   * a lot.
   */
  function ensure_my_table() {
    if (!isset($this->table_alias)) {
      if (!method_exists($this->query, 'ensure_table')) { vpr_trace(); exit; }
      $this->table_alias = $this->query->ensure_table($this->table, $this->relationship);
    }
    return $this->table_alias;
  }

  /**
   * Provide text for the administrative summary
   */
  function admin_summary() { }

  /**
   * Determine if the argument needs a style plugin.
   *
   * @return TRUE/FALSE
   */
  function needs_style_plugin() { return FALSE; }

  /**
   * Determine if this item is 'exposed', meaning it provides form elements
   * to let users modify the view.
   *
   * @return TRUE/FALSE
   */
  function is_exposed() {
    return !empty($this->options['exposed']);
  }

  /**
   * Take input from exposed handlers and assign to this handler, if necessary.
   */
  function accept_exposed_input($input) { return TRUE; }

  /**
   * If set to remember exposed input in the session, store it there.
   */
  function store_exposed_input($input, $status) { return TRUE; }

  /**
   * Get the join object that should be used for this handler.
   *
   * This method isn't used a great deal, but it's very handy for easily
   * getting the join if it is necessary to make some changes to it, such
   * as adding an 'extra'.
   */
  function get_join() {
    // get the join from this table that links back to the base table.
    // Determine the primary table to seek
    if (empty($this->query->relationships[$this->relationship])) {
      $base_table = $this->query->base_table;
    }
    else {
      $base_table = $this->query->relationships[$this->relationship]['base'];
    }

    $join = views_get_table_join($this->table, $base_table);
    if ($join) {
      return drupal_clone($join);
    }
  }

  /**
   * Validates the handler against the complete View.
   *
   * This is called when the complete View is being validated. For validating
   * the handler options form use options_validate().
   *
   * @see views_handler::options_validate()
   *
   * @return
   *   Empty array if the handler is valid; an array of error strings if it is not.
   */
  function validate() { return array(); }

  /**
   * Determine if the handler is considered 'broken', meaning it's a
   * a placeholder used when a handler can't be found.
   */
  function broken() { }
}

/**
 * This many to one helper object is used on both arguments and filters.
 *
 * @todo This requires extensive documentation on how this class is to
 * be used. For now, look at the arguments and filters that use it. Lots
 * of stuff is just pass-through but there are definitely some interesting
 * areas where they interact.
 *
 * Any handler that uses this can have the following possibly additional
 * definition terms:
 * - numeric: If true, treat this field as numeric, using %d instead of %s in
 *            queries.
 *
 */
class views_many_to_one_helper {
  function views_many_to_one_helper(&$handler) {
    $this->handler = &$handler;
  }

  function option_definition(&$options) {
    $options['reduce_duplicates'] = array('default' => FALSE);
  }

  function options_form(&$form, &$form_state) {
    $form['reduce_duplicates'] = array(
      '#type' => 'checkbox',
      '#title' => t('Reduce duplicates'),
      '#description' => t('This filter can cause items that have more than one of the selected options to appear as duplicate results. If this filter causes duplicate results to occur, this checkbox can reduce those duplicates; however, the more terms it has to search for, the less performant the query will be, so use this with caution.'),
      '#default_value' => !empty($this->handler->options['reduce_duplicates']),
    );
  }

  /**
   * Sometimes the handler might want us to use some kind of formula, so give
   * it that option. If it wants us to do this, it must set $helper->formula = TRUE
   * and implement handler->get_formula();
   */
  function get_field() {
    if (!empty($this->formula)) {
      return $this->handler->get_formula();
    }
    else {
      return $this->handler->table_alias . '.' . $this->handler->real_field;
    }
  }

  /**
   * Add a table to the query.
   *
   * This is an advanced concept; not only does it add a new instance of the table,
   * but it follows the relationship path all the way down to the relationship
   * link point and adds *that* as a new relationship and then adds the table to
   * the relationship, if necessary.
   */
  function add_table($join = NULL, $alias = NULL) {
    // This is used for lookups in the many_to_one table.
    $field = $this->handler->table . '.' . $this->handler->field;

    if (empty($join)) {
      $join = $this->get_join();
    }

    // See if there's a chain between us and the base relationship. If so, we need
    // to create a new relationship to use.
    $relationship = $this->handler->relationship;

    // Determine the primary table to seek
    if (empty($this->handler->query->relationships[$relationship])) {
      $base_table = $this->handler->query->base_table;
    }
    else {
      $base_table = $this->handler->query->relationships[$relationship]['base'];
    }

    // Cycle through the joins. This isn't as error-safe as the normal
    // ensure_path logic. Perhaps it should be.
    $r_join = drupal_clone($join);
    while ($r_join->left_table != $base_table) {
      $r_join = views_get_table_join($r_join->left_table, $base_table);
    }

    // If we found that there are tables in between, add the relationship.
    if ($r_join->table != $join->table) {
      $relationship = $this->handler->query->add_relationship($this->handler->table, $r_join, $r_join->table, $this->handler->relationship);
    }

    // And now add our table, using the new relationship if one was used.
    $alias = $this->handler->query->add_table($this->handler->table, $relationship, $join, $alias);

    // Store what values are used by this table chain so that other chains can
    // automatically discard those values.
    if (empty($this->handler->view->many_to_one_tables[$field])) {
      $this->handler->view->many_to_one_tables[$field] = $this->handler->value;
    }
    else {
      $this->handler->view->many_to_one_tables[$field] = array_merge($this->handler->view->many_to_one_tables[$field], $this->handler->value);
    }

    return $alias;
  }

  function get_join() {
    return $this->handler->get_join();
  }

  /**
   * Provide the proper join for summary queries. This is important in part because
   * it will cooperate with other arguments if possible.
   */
  function summary_join() {
    $field = $this->handler->table . '.' . $this->handler->field;
    $join = $this->get_join();

    // shortcuts
    $options = $this->handler->options;
    $view = &$this->handler->view;
    $query = &$this->handler->query;

    if (!empty($options['require_value'])) {
      $join->type = 'INNER';
    }

    if (empty($options['add_table']) || empty($view->many_to_one_tables[$field])) {
      return $query->ensure_table($this->handler->table, $this->handler->relationship, $join);
    }
    else {
      if (!empty($view->many_to_one_tables[$field])) {
        foreach ($view->many_to_one_tables[$field] as $value) {
          $join->extra = array(
            array(
              'field' => $this->handler->real_field,
              'operator' => '!=',
              'value' => $value,
              'numeric' => !empty($this->definition['numeric']),
            ),
          );
        }
      }
      return $this->add_table($join);
    }
  }

  /**
   * Override ensure_my_table so we can control how this joins in.
   * The operator actually has influence over joining.
   */
  function ensure_my_table() {
    if (!isset($this->handler->table_alias)) {
      // For 'or' if we're not reducing duplicates, we get the absolute simplest:
      $field = $this->handler->table . '.' . $this->handler->field;
      if ($this->handler->operator == 'or' && empty($this->handler->options['reduce_duplicates'])) {
        if (empty($this->handler->options['add_table']) && empty($this->handler->view->many_to_one_tables[$field])) {
          // query optimization, INNER joins are slightly faster, so use them
          // when we know we can.
          $join = $this->get_join();
          $join->type = 'INNER';
          $this->handler->table_alias = $this->handler->query->ensure_table($this->handler->table, $this->handler->relationship, $join);
          $this->handler->view->many_to_one_tables[$field] = $this->handler->value;
        }
        else {
          $join = $this->get_join();
          $join->type = 'LEFT';
          if (!empty($this->handler->view->many_to_one_tables[$field])) {
            foreach ($this->handler->view->many_to_one_tables[$field] as $value) {
              $join->extra = array(
                array(
                  'field' => $this->handler->real_field,
                  'operator' => '!=',
                  'value' => $value,
                  'numeric' => !empty($this->handler->definition['numeric']),
                ),
              );
            }
          }

          $this->handler->table_alias = $this->add_table($join);
        }

        return $this->handler->table_alias;
      }

      if ($this->handler->operator != 'not') {
        // If it's an and or an or, we do one join per selected value.
        // Clone the join for each table:
        $this->handler->table_aliases = array();
        foreach ($this->handler->value as $value) {
          $join = $this->get_join();
          if ($this->handler->operator == 'and') {
            $join->type = 'INNER';
          }
          $join->extra = array(
            array(
              'field' => $this->handler->real_field,
              'value' => $value,
              'numeric' => !empty($this->handler->definition['numeric']),
            ),
          );

          // The table alias needs to be unique to this value across the
          // multiple times the filter or argument is called by the view.
          if (!isset($this->handler->view->many_to_one_aliases[$field][$value])) {
            if (!isset($this->handler->view->many_to_one_count[$this->handler->table])) {
              $this->handler->view->many_to_one_count[$this->handler->table] = 0;
            }
            $this->handler->view->many_to_one_aliases[$field][$value] = $this->handler->table . '_value_' . ($this->handler->view->many_to_one_count[$this->handler->table]++);
          }
          $alias = $this->handler->table_aliases[$value] = $this->add_table($join, $this->handler->view->many_to_one_aliases[$field][$value]);

          // and set table_alias to the first of these.
          if (empty($this->handler->table_alias)) {
            $this->handler->table_alias = $alias;
          }
        }
      }
      else {
        // For not, we just do one join. We'll add a where clause during
        // the query phase to ensure that $table.$field IS NULL.
        $join = $this->get_join();
        $join->type = 'LEFT';
        $join->extra = array();
        $join->extra_type = 'OR';
        foreach ($this->handler->value as $value) {
          $join->extra[] = array(
            'field' => $this->handler->real_field,
            'value' => $value,
            'numeric' => !empty($this->handler->definition['numeric']),
          );
        }

        $this->handler->table_alias = $this->add_table($join);
      }
    }
    return $this->handler->table_alias;
  }

  function add_filter() {
    if (empty($this->handler->value)) {
      return;
    }
    $this->handler->ensure_my_table();

    // Shorten some variables:
    $field = $this->get_field();
    $options = $this->handler->options;
    $operator = $this->handler->operator;
    if (empty($options['group'])) {
      $options['group'] = 0;
    }

    $placeholder = !empty($this->handler->definition['numeric']) ? '%d' : "'%s'";

    if ($operator == 'not') {
      $this->handler->query->add_where($options['group'], "$field IS NULL");
    }
    else if ($operator == 'or' && empty($options['reduce_duplicates'])) {
      if (count($this->handler->value) > 1) {
        $replace = array_fill(0, sizeof($this->handler->value), $placeholder);
        $in = '(' . implode(", ", $replace) . ')';
        $this->handler->query->add_where($options['group'], "$field IN $in", $this->handler->value);
      }
      else {
        $this->handler->query->add_where($options['group'], "$field = $placeholder", $this->handler->value);
      }
    }
    else {
      $field = $this->handler->real_field;
      $clauses = array();
      foreach ($this->handler->table_aliases as $value => $alias) {
        $clauses[] = "$alias.$field = $placeholder";
      }

      $group = empty($options['group']) ? 0 : $options['group'];

      // implode on either AND or OR.
      $this->handler->query->add_where($group, implode(' ' . strtoupper($operator) . ' ', $clauses), $this->handler->value);
    }
  }
}

/*
 * Break x,y,z and x+y+z into an array. Numeric only.
 *
 * @param $str
 *   The string to parse.
 * @param $filter
 *   The filter object to use as a base. If not specified one will
 *   be created.
 *
 * @return $filter
 *   The new filter object.
 */
function views_break_phrase($str, $filter = NULL) {
  if (!$filter) {
    $filter = new stdClass();
  }
  if (preg_match('/^([0-9]+[+ ])+[0-9]+$/', $str)) {
    // The '+' character in a query string may be parsed as ' '.
    $filter->operator = 'or';
    $filter->value = preg_split('/[+ ]/', $str);
  }
  else if (preg_match('/^([0-9]+,)*[0-9]+$/', $str)) {
    $filter->operator = 'and';
    $filter->value = explode(',', $str);
  }

  // Keep an 'error' value if invalid strings were given.
  if (!empty($str) && (empty($filter->value) || !is_array($filter->value))) {
    $filter->value = array(-1);
    return $filter;
  }

  // Doubly ensure that all values are numeric only.
  foreach ($filter->value as $id => $value) {
    $filter->value[$id] = intval($value);
  }

  return $filter;
}

// --------------------------------------------------------------------------
// Date helper functions

/**
 * Figure out what timezone we're in; needed for some date manipulations.
 */
function views_get_timezone() {
  global $user;
  if (variable_get('configurable_timezones', 1) && $user->uid && strlen($user->timezone)) {
    $timezone = $user->timezone;
  }
  else {
    $timezone = variable_get('date_default_timezone', 0);
  }

  // set up the database timezone
  if (in_array($GLOBALS['db_type'], array('mysql', 'mysqli'))) {
    static $already_set = false;
    if (!$already_set) {
      if ($GLOBALS['db_type'] == 'mysqli' || version_compare(mysql_get_server_info(), '4.1.3', '>=')) {
        db_query("SET @@session.time_zone = '+00:00'");
      }
      $already_set = true;
    }
  }

  return $timezone;
}

/**
 * Helper function to create cross-database SQL dates.
 *
 * @param $field
 *   The real table and field name, like 'tablename.fieldname'.
 * @param $field_type
 *   The type of date field, 'int' or 'datetime'.
 * @param $set_offset
 *   The name of a field that holds the timezone offset or a fixed timezone
 *   offset value. If not provided, the normal Drupal timezone handling
 *   will be used, i.e. $set_offset = 0 will make no timezone adjustment.
 * @return
 *   An appropriate SQL string for the db type and field type.
 */
function views_date_sql_field($field, $field_type = 'int', $set_offset = NULL) {
  $db_type = $GLOBALS['db_type'];
  $offset = $set_offset !== NULL ? $set_offset : views_get_timezone();
  switch ($db_type) {
    case 'mysql':
    case 'mysqli':
      switch ($field_type) {
        case 'int':
          $field = "FROM_UNIXTIME($field)";
          break;
        case 'datetime':
          break;
      }
      if (!empty($offset)) {
        $field = "($field + INTERVAL $offset SECOND)";
      }
      return $field;
    case 'pgsql':
      switch ($field_type) {
        case 'int':
          $field = "$field::ABSTIME";
          break;
        case 'datetime':
          break;
      }
      if (!empty($offset)) {
        $field = "($field + INTERVAL '$offset SECONDS')";
      }
      return $field;
  }
}

/**
 * Helper function to create cross-database SQL date formatting.
 *
 * @param $format
 *   A format string for the result, like 'Y-m-d H:i:s'.