具有完整父项的平面数组(PHP、Symfony 3)

$array = [
    ['id' => 1, 'name' => 'A', 'parent' => null],
    ['id' => 2, 'name' => 'B', 'parent' => 1],
    ['id' => 3, 'name' => 'C', 'parent' => 1],
    ['id' => 4, 'name' => 'D', 'parent' => 2],
    // ...
];

function buildTree($array, $parentId = null) {
    $tree = [];
    foreach ($array as $element) {
        if ($element['parent'] == $parentId) {
            $children = buildTree($array, $element['id']);
            if ($children) {
                $element['children'] = $children;
            }
            $tree[] = $element;
        }
    }
    return $tree;
}

$tree = buildTree($array);