feeds.module

 *   feeds_library_exists() will look for libraries with this name managed by
 *   libraries module.
 */
function feeds_library_exists($file, $library) {

  if (module_exists('libraries') && file_exists(libraries_get_path($library) . "/$file")) {
    return TRUE;
  }

  elseif (file_exists(DRUPAL_ROOT . '/' . drupal_get_path('module', 'feeds') . "/libraries/$file")) {
    return TRUE;
  }

  elseif ($library_dir = variable_get('feeds_library_dir', FALSE)) {
    if (file_exists("$library_dir/$library/$file")) {
      return TRUE;
    }
  }

  return FALSE;
}

 /**
 * Checks whether simplepie exists.
 */
function feeds_simplepie_exists() {
  return (feeds_library_exists('simplepie.compiled.php', 'simplepie') ||
    feeds_library_exists('simplepie.mini.php', 'simplepie') ||
    feeds_library_exists('simplepie.inc', 'simplepie')
  );
}

/**
 * Includes the simplepie library.
 */
function feeds_include_simplepie() {
  $files = array('simplepie.mini.php', 'simplepie.compiled.php', 'simplepie.inc');

  foreach ($files as $file) {
    if (feeds_include_library($file, 'simplepie')) {
      return TRUE;
    }
  }
  return FALSE;
}

/**
 * @}
 */

/**
 * Copy of valid_url() that supports the webcal scheme.
 *
 * @see valid_url().
 *
 * @todo Replace with valid_url() when http://drupal.org/node/295021 is fixed.
 */
function feeds_valid_url($url, $absolute = FALSE) {
  if ($absolute) {
    return (bool) preg_match("
      /^                                                      # Start at the beginning of the text
      (?:ftp|https?|feed|webcal):\/\/                         # Look for ftp, http, https, feed or webcal schemes
      (?:                                                     # Userinfo (optional) which is typically
        (?:(?:[\w\.\-\+!$&'\(\)*\+,;=]|%[0-9a-f]{2})+:)*      # a username or a username and password
        (?:[\w\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})+@          # combination
      )?
      (?:
        (?:[a-z0-9\-\.]|%[0-9a-f]{2})+                        # A domain name or a IPv4 address
        |(?:\[(?:[0-9a-f]{0,4}:)*(?:[0-9a-f]{0,4})\])         # or a well formed IPv6 address
      )
      (?::[0-9]+)?                                            # Server port number (optional)
      (?:[\/|\?]
        (?:[|\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})   # The path and query (optional)
      *)?
    $/xi", $url);
  }
  else {
    return (bool) preg_match("/^(?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})+$/i", $url);
  }
}

/**
 * Registers a feed subscription job for execution on feeds_exit().
 *
 * @param array $job
 *   Information about a new job to queue; or if set to NULL (default), leaves
 *   the current queued jobs unchanged.
 *
 * @return
 *   An array of subscribe jobs to process.
 *
 * @see feeds_exit()
 * @see feeds_get_subscription_jobs()
 */
function feeds_set_subscription_job(array $job = NULL) {
  $jobs = &drupal_static(__FUNCTION__, array());
  if (isset($job)) {
    $jobs[] = $job;
  }
  return $jobs;
}

/**
 * Returns the list of queued jobs to be run.
 *
 * @return
 *   An array of subscribe jobs to process.
 *
 * @see feeds_set_subscription_job()
 */
function feeds_get_subscription_jobs() {
  return feeds_set_subscription_job();
}

/**
 * Implements hook_entity_property_info_alter().
 */
function feeds_entity_property_info_alter(&$info) {
  // Gather entities supported by Feeds processors.
  $processors = FeedsPlugin::byType('processor');
  $supported_entities = array();
  foreach ($processors as $processor) {
    $instance = feeds_plugin($processor['handler']['class'], '__none__');
    if (method_exists($instance, 'entityType')) {
      $supported_entities[] = $instance->entityType();
    }
  }
  // Feeds processors can fake the entity info. Only set the property for
  // defined entities.
  $supported_entities = array_intersect(array_keys($info), $supported_entities);

  foreach ($supported_entities as $entity_type) {
    $info[$entity_type]['properties']['feed_nid'] = array(
      'label' => 'Feed NID',
      'type' => 'integer',
      'description' => t('Nid of the Feed Node that imported this entity.'),
      'getter callback' => 'feeds_get_feed_nid_entity_callback',
    );
  }
}

/**
 * Gets the feed_nid for an entity for use in entity metadata.
 */
function feeds_get_feed_nid_entity_callback($entity, array $options, $name, $entity_type) {
  list($entity_id, , ) = entity_extract_ids($entity_type, $entity);

  $feed_nid = feeds_get_feed_nid($entity_id, $entity_type);

  if ($feed_nid === FALSE) {
    return NULL;
  }
  return $feed_nid;
}