bp_activity_filter_mentions_scope( array $retval = array(), array $filter = array() )

function bp_activity_filter_mentions_scope( $retval = array(), $filter = array() ) {

	// Are mentions disabled?
	if ( ! bp_activity_do_mentions() ) {
		return $retval;
	}

	// Determine the user_id.
	if ( ! empty( $filter['user_id'] ) ) {
		$user_id = $filter['user_id'];
	} else {
		$user_id = bp_displayed_user_id()
			? bp_displayed_user_id()
			: bp_loggedin_user_id();
	}

	// Should we show all items regardless of sitewide visibility?
	$show_hidden = array();
	if ( ! empty( $user_id ) && $user_id !== bp_loggedin_user_id() ) {
		$show_hidden = array(
			'column' => 'hide_sitewide',
			'value'  => 0
		);
	}

	$retval = array(
		'relation' => 'AND',
		array(
			'column'  => 'content',
			'compare' => 'LIKE',

			// Start search at @ symbol and stop search at closing tag delimiter.
			'value'   => '@' . bp_activity_get_user_mentionname( $user_id ) . '<'
		),
		$show_hidden,

		// Overrides.
		'override' => array(
			'display_comments' => bp_show_streamed_activity_comment()? 'stream' : 'threaded',
			'filter'           => array( 'user_id' => 0 ),
			'show_hidden'      => true
		),
	);

	return $retval;
}