Automattic / jetpack

		// ----------------------------------- MENTIONS ------------------------------

		if ( self::MENTIONS & $what_to_extract ) {

			if ( preg_match_all( '/(^|\s)@(\w+)/u', $stripped_content, $matches ) ) {

				$mentions             = array_values( array_unique( $matches[2] ) ); // array_unique() retains the keys!

				$mentions             = array_map( 'strtolower', $mentions );

				$extracted['mention'] = array( 'name' => $mentions );

				if ( ! isset( $extracted['has'] ) ) {

					$extracted['has'] = array();

				}

				$extracted['has']['mention'] = count( $mentions );

			}

		}

		// ----------------------------------- HASHTAGS ------------------------------

			// This regex does not exactly match Twitter's

			// if there are problems/complaints we should implement this:

			// https://github.com/twitter/twitter-text/blob/master/java/src/com/twitter/Regex.java .

			if ( preg_match_all( '/(?:^|\s)#(\w*\p{L}+\w*)/u', $stripped_content, $matches ) ) {

				$hashtags             = array_values( array_unique( $matches[1] ) ); // array_unique() retains the keys!

				$hashtags             = array_map( 'strtolower', $hashtags );

				$extracted['hashtag'] = array( 'name' => $hashtags );

				if ( ! isset( $extracted['has'] ) ) {

					$extracted['has'] = array();

				}

				$extracted['has']['hashtag'] = count( $hashtags );

			}

		}