我找到了这个代码：

function completionTree(&$elem, &$parent=NULL) {
// Handle arrays that are used only as a container... if we have children but no uuid, simply descend.
    if (is_array($elem) && !isset($elem['uuid'])) {
        foreach($elem AS &$child) {
            completionTree($child, $elem);
        }
    }

    if (!empty($elem['children'])) {
        foreach ($elem['children'] AS &$child) {
            completionTree($child, $elem);
        }
    }
    if (@$parent['completed'] !== NULL) {
        $parent['completed'] = $parent['completed'] + $elem['completed'];
    }
}
// Launch recursive calculations
completionTree($tree);

它可以工作，但它是在过程中，有谁知道如何使这在oop类功能的工作？
谢谢...

有了给定的结构，

function rcount(&$array) {
    $count = 0;
    foreach ($array as $foldername => &$entry) {
        if (isset($entry['items'])) {
            $entry['new'] += rcount($entry['items']);
        }
        $count += $entry['new'];
    }
    return $count;
}

它将对直接子节点上的“new”条目求和，但在此之前，它将递归到每个子节点，并让它计算其“new”总和（并将其加到当前的new数目）。通过这种方式，内部数字被向上传输。
使用给定的（bugfixed）结构的代码的结果将给出以下输出，但请随意使用更大/更深的结构。

Array
(
    [FOLDER_1] => Array
        (
            [name] => FOLDER 1
            [new] => 2
            [items] => Array
                (
                    [SUB_FOLDER_1_1] => Array
                        (
                            [name] => SUB FOLDER 1 1
                            [new] => 1
                            [items] => Array
                                (
                                    [SUB_FILE_1_1_1] => Array
                                        (
                                            [name] => SUB FILE 1 1 1
                                            [new] => 0
                                        )

                                    [SUB_FILE_1_1_2] => Array
                                        (
                                            [name] => SUB FILE 1 1 2
                                            [new] => 1
                                        )

                                )

                        )

                    [SUB_FILE_1_1] => Array
                        (
                            [name] => SUB FILE 1 1
                            [new] => 1
                        )

                )

        )

    [FOLDER_2] => Array
        (
            [name] => FOLDER 1
            [new] => 0
            [items] => Array
                (
                )

        )

)