materio-base-d7/sites/all/modules/contrib/admin/workflow/workflow_search_api/workflow_search_api.module

<?php
/**
 * @file
 * Adds workflow state information to Search API index.
 */

/**
 * Implements hook_entity_property_info_alter().
 */
function workflow_search_api_entity_property_info_alter(&$info) {
  $info['node']['properties']['workflow_state_name'] = array(
    'type' => 'text',
    'label' => t('Workflow state name'),
    'sanitized' => TRUE,
    'getter callback' => 'workflow_search_api_property_workflow_state_getter_callback',
    );
}

/**
 * Getter callback for workflow state defined in workflow_search_api_entity_property_info_alter.
 */
function workflow_search_api_property_workflow_state_getter_callback($item) {
  if ($item->workflow) {
    // Get text value of workflow state.
    $state = workflow_get_workflow_states_by_sid($item->workflow);
    $state_name = $state->state;
  }
  else {
    $state_name = '';
  }

  return $state_name;
}