How to sort an array with dependencies?

Question

PHP

There is an array inside which elements can depend on each other. For example, like this:

$items = [
  'item_a' => ['require' => ['item_b']], // этот элемент зависит от 'item_b'
  'item_b' => ['require' => []], // этот элемент не зависит от других
  'item_c' => ['require' => ['item_a']],
  'item_d' => ['require' => ['item_a', 'item_e']], // этот элемент зависит сразу от двух других - 'item_a' и 'item_b'
  'item_e' => ['require' => ['item_a']],
];

And you need to sort it so that the dependent elements always go after the elements on which they depend. In my example, the order of keys as a result of sorting will be:
'item_b', 'item_a', 'item_c', 'item_e', 'item_d'
Actually, the question is: how to perform such sorting? Ideally, if there are some ready-made libraries for such sorting.
PS. Ash stump, that there may be cyclic dependencies and this must also be taken into account somehow.

Answer 1

How do you propose to sort this?

$items = [
    'item_a' => ['require' => ['item_b']],
    'item_b' => ['require' => ['item_с']],
    'item_c' => ['require' => ['item_a']],
];

If there are no cycles and interdependencies, then like this:

foreach (array_keys($items) as $key) {
    $items[$key]['name'] = $key;
}

uasort($items, function($a, $b) {
    return (in_array($b['name'], $a['require']) || empty($b['require']));
});

https://ideone.com/ClHFqW
To search for cyclic dependencies, I got the following function:

/**
 * @param array $items
 * @return bool
 */
function search_cycle($items)
{
    $search = function(array $path) use ($items, &$search)
    {
        $count = count($path);
        $first = $path[0];
        $last  = $path[$count - 1];
        if ($count > 1 && in_array($last, array_slice($path, 0, $count - 1))) {
            return true;
        }
        
        foreach ($items[$last]['require'] as $key) {
            if ($search(array_merge($path, [$key]))) {
                return true;
            }
        }
        
        return false;
    };
    
    foreach ($items as $key => $data) {
        if ($search([$key])) {
            return true;
        }
    }
    
    return false;
}