bbp_convert_mentions( string $data )

function bbp_convert_mentions( $data ) {

	// Search mentions in the content.
	$usernames = bp_find_mentions_by_at_sign( array(), $data );

	// We have mentions!
	if ( ! empty( $usernames ) ) {
		foreach ( (array) $usernames as $user_id => $username ) {
			$data = preg_replace( '/(@' . $username . '\b)/', "<a class='bp-suggestions-mention' href='" . bbp_get_user_profile_url( $user_id ) . "' rel='nofollow'>@$username</a>", $data );
		}

		// Temporary variable to avoid having to run bp_find_mentions_by_at_sign() again.
		buddypress()->forums->mentioned_users = $usernames;
	}

	return $data;
}