bp_core_get_post_slug_by_index( $dir_index_file )

function bp_core_get_post_slug_by_index( $dir_index_file ) {
	$dir_file_array = explode( '/', $dir_index_file );
	$index_file     = db_core_remove_file_extension_from_slug( end( $dir_file_array ) );

	return db_core_remove_file_number_from_slug( $index_file );
}