materio-base-d7/sites/all/modules/contrib/fields/hierarchical_select/modules/hs_flatlist.module

<?php

/**
 * @file
 * Implementation of the Hierarchical Select API that allows one to use
 * Hierarchical Select's dropbox for selecting multiple items of a flat list.
 */


//----------------------------------------------------------------------------
// Hierarchical Select hooks.

/**
 * Implements hook_hierarchical_select_params().
 */
function hs_flatlist_hierarchical_select_params() {
  $params = array(
    'options',
  );
  return $params;
}

/**
 * Implements hook_hierarchical_select_root_level().
 */
function hs_flatlist_hierarchical_select_root_level($params) {
  return $params['options'];
}

/**
 * Implements hook_hierarchical_select_children().
 */
function hs_flatlist_hierarchical_select_children($parent, $params) {
  return array(); // A flat list doesn't have any children, ever.
}

/**
 * Implements hook_hierarchical_select_lineage().
 */
function hs_flatlist_hierarchical_select_lineage($item, $params) {
  return array($item); // No hierarchies exist in flat lists.
}

/**
 * Implements hook_hierarchical_select_valid_item().
 */
function hs_flatlist_hierarchical_select_valid_item($item, $params) {
  return (in_array($item, array_keys($params['options'])));
}

/**
 * Implements hook_hierarchical_select_item_get_label().
 */
function hs_flatlist_hierarchical_select_item_get_label($item, $params) {
  return $params['options'][$item];
}

/**
 * Implements hook_hierarchical_select_implementation_info().
 */
function hs_flatlist_hierarchical_select_implementation_info() {
  return array(
    'hierarchy type' => t('None: flat list'),
    'entity type'    => t('N/A'),
  );
}