makeTree

maketree.php

<?php
function makeTree($list, $parent)
{
    $tree = [];
    foreach ($list as $item) {
        if ($item['parent'] == $parent) {
            $tree[$item['id']] = makeTree($list, $item['id']);
        } else {
            continue;
        }
    }

    return $tree;
}

// Usage:
$data = [
    0 => ['id' => 1, 'parent' => 0],
    1 => ['id' => 2, 'parent' => 1],
    2 => ['id' => 3, 'parent' => 2]
];
print_r(makeTree($data, 0));

// Output: 
/*
Array
(
    [0] => Array
        (
            [1] => Array
                (
                    [2] => Array()
                )
        )
)
*/