MemberPress: Exclude Protected Posts from Search Results

function maybe_exclude_protected_posts($query) {

  if(!$query->is_admin && $query->is_search && $query->is_main_query()) {

    $posts_to_exclude = array();

    $posts = get_posts(array(

      'post_type' => get_post_types(),

      'numberposts' => -1

    ));

    foreach($posts as $post) {

      if(MeprRule::is_locked($post)) {

        $posts_to_exclude[] = $post->ID;

      }

    }

    if(!empty($posts_to_exclude)) {

      $query->set('post__not_in', $posts_to_exclude);

    }

  }

}

add_action('pre_get_posts', 'maybe_exclude_protected_posts');