sort-by-spec.php

<?php

class Sorter
{
    private $callback;

    public function __construct(array $orderBy)
    {
        $functions = [];

        foreach ($orderBy as $field => $order) {
            $multiplier = strtolower($order) === 'desc' ? -1 : 1;

            $functions[] = function (array $a, array $b) use ($field, $multiplier) : int {
                if (! isset($a[$field], $b[$field])) {
                    return 0;
                }

                return (
                    !isset($a[$field]) <=> !isset($b[$field]) ?: $a[$field] <=> $b[$field]
                ) * $multiplier;
            };
        }

        $this->callback = function (array $a, array $b) use ($functions) : int {
            foreach ($functions as $function) {
                $result = $function($a, $b);

                if ($result !== 0) {
                    return $result;
                }
            }

            return 0;
        };
    }

    public function __invoke(array $a, array $b) : int
    {
        return ($this->callback)($a, $b);
    }
}

$sorter = new Sorter(['a' => 'asc']);

$data = [
    ['a' => 'y'],
    ['a' => 'x'],
];
usort($data, $sorter);

var_dump($data);