RecursiveParentChildIterator —— 就像 RecursiveDirectoryIterator

发布于 2024-08-30 09:08:57 字数 762 浏览 7 评论 0原文

有大量使用 RecursiveIterator 来展平树结构的示例。但是使用它来分解树结构怎么样？

有没有一种优雅的方法来使用这个，或者其他一些 SPL 库来递归地构建一棵树（阅读：将平面数组转换为任意深度的数组）给定这样的表：

SELECT id, parent_id, name FROM my_tree

编辑： 您知道如何使用目录来做到这一点吗？

$it = new RecursiveDirectoryIterator("/var/www/images");
foreach(new RecursiveIteratorIterator($it) as $file) {
    echo $file . PHP_EOL;
}

..如果你可以做这样的事情会怎样：

$it = new RecursiveParentChildIterator($result_array);
foreach(new RecursiveIteratorIterator($it) as $group) {
    echo $group->name . PHP_EOL;
    // this would contain all of the children of this group, recursively
    $children = $group->getChildren();
}

:END EDIT

原文

There are tons of examples of using the RecursiveIterator to flatten a tree structure.. but what about using it to explode a tree structure?

Is there an elegant way to use this, or some other SPL library to recursively build a tree (read: turn a flat array into array of arbitrary depth) given a table like this:

SELECT id, parent_id, name FROM my_tree

EDIT:
You know how you can do this with Directories?

$it = new RecursiveDirectoryIterator("/var/www/images");
foreach(new RecursiveIteratorIterator($it) as $file) {
    echo $file . PHP_EOL;
}

.. What if you could do something like this:

$it = new RecursiveParentChildIterator($result_array);
foreach(new RecursiveIteratorIterator($it) as $group) {
    echo $group->name . PHP_EOL;
    // this would contain all of the children of this group, recursively
    $children = $group->getChildren();
}

:END EDIT

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傲鸠 2024-09-06 09:08:57

虽然不是 SPL，但您可以使用引用 (&) 与原生 PHP 构建树：

// untested
$nodeList = array();
$tree     = array();
foreach ($result as $row) {
    $nodeList[$row['id']] = array_merge($row, array('children' => array()));
}
foreach ($nodeList as $nodeId => &$node) {
    if (!$node['parent_id'] || !array_key_exists($node['parent_id'], $nodeList)) {
        $tree[] = &$node;
    } else {
        $nodeList[$node['parent_id']]['children'][] = &$node;
    }
}
unset($node);
unset($nodeList);

Though not SPL, but you can use references (&) build up a tree with native PHP:

// untested
$nodeList = array();
$tree     = array();
foreach ($result as $row) {
    $nodeList[$row['id']] = array_merge($row, array('children' => array()));
}
foreach ($nodeList as $nodeId => &$node) {
    if (!$node['parent_id'] || !array_key_exists($node['parent_id'], $nodeList)) {
        $tree[] = &$node;
    } else {
        $nodeList[$node['parent_id']]['children'][] = &$node;
    }
}
unset($node);
unset($nodeList);

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