查找后this answer, 我选择了：

$template_tree = mytheme_get_template_tree();
$total = count($template_tree); //count the elements in the array
end($template_tree); //set the pointer to the end of the array
$immediate_parent = basename(prev($template_tree)); //get the filename of the penultimate element

function mytheme_get_template_tree()
{
    $included_files = get_included_files();
    $stylesheet_dir = str_replace( \'\\\\\', \'/\', get_stylesheet_directory() );
    $template_dir   = str_replace( \'\\\\\', \'/\', get_template_directory() );

    foreach ( $included_files as $key => $path ) {

        $path = str_replace( \'\\\\\', \'/\', $path );

        if ( FALSE === strpos( $path, $stylesheet_dir ) && FALSE === strpos( $path, $template_dir ) ) {
            unset( $included_files[ $key ] );
        }
    }

    return $included_files;

}