+/**
+ * Build SimplePie object based on RSS or Atom feed from URL.
+ *
+ * @since 2.8.0
+ *
+ * @param mixed $url URL of feed to retrieve. If an array of URLs, the feeds are merged
+ * using SimplePie's multifeed feature.
+ * See also {@link ​http://simplepie.org/wiki/faq/typical_multifeed_gotchas}
+ *
+ * @return WP_Error|SimplePie WP_Error object on failure or SimplePie object on success
+ */
+function fetch_feed( $url ) {
+ if ( ! class_exists( 'SimplePie', false ) ) {
+ require_once( ABSPATH . WPINC . '/class-simplepie.php' );
+ }
+
+ require_once( ABSPATH . WPINC . '/class-wp-feed-cache.php' );
+ require_once( ABSPATH . WPINC . '/class-wp-feed-cache-transient.php' );
+ require_once( ABSPATH . WPINC . '/class-wp-simplepie-file.php' );
+ require_once( ABSPATH . WPINC . '/class-wp-simplepie-sanitize-kses.php' );
+
+ $feed = new SimplePie();
+
+ $feed->set_sanitize_class( 'WP_SimplePie_Sanitize_KSES' );
+ // We must manually overwrite $feed->sanitize because SimplePie's
+ // constructor sets it before we have a chance to set the sanitization class
+ $feed->sanitize = new WP_SimplePie_Sanitize_KSES();
+
+ $feed->set_cache_class( 'WP_Feed_Cache' );
+ $feed->set_file_class( 'WP_SimplePie_File' );
+
+ $feed->set_feed_url( $url );
+ /** This filter is documented in wp-includes/class-wp-feed-cache-transient.php */
+ $feed->set_cache_duration( apply_filters( 'wp_feed_cache_transient_lifetime', 12 * HOUR_IN_SECONDS, $url ) );
+ /**
+ * Fires just before processing the SimplePie feed object.
+ *
+ * @since 3.0.0
+ *
+ * @param object &$feed SimplePie feed object, passed by reference.
+ * @param mixed $url URL of feed to retrieve. If an array of URLs, the feeds are merged.
+ */
+ do_action_ref_array( 'wp_feed_options', array( &$feed, $url ) );
+ $feed->init();
+ $feed->set_output_encoding( get_option( 'blog_charset' ) );
+
+ if ( $feed->error() )
+ return new WP_Error( 'simplepie-error', $feed->error() );
+
+ return $feed;
+}