Permutation PHP Class

permutation.class.php

<?php

$permutation = new Permutation();
// $permutation = new Permutation(array_rand(range(0, 100), 4));

class Permutation
{
    private $data = [];
    private $permutations = [];

    public function __construct($data = ['a', 'b', 'c', 'd'])
    {
        $this->data = $data;
        $this->calculatePermutations();
        $this->listPermutations();
    }

    public static function permutations(array $elements)
    {
        if (count($elements) <= 1) {
            yield $elements;
        } else {
            foreach (self::permutations(array_slice($elements, 1)) as $permutation) {
                foreach (range(0, count($elements) - 1) as $i) {
                    yield array_merge(
                        array_slice($permutation, 0, $i),
                        [$elements[0]],
                        array_slice($permutation, $i)
                    );
                }
            }
        }
    }

    public function setData($data)
    {
        $this->data = $data;
    }

    public function calculatePermutations()
    {
        $this->permutations = [];
        foreach (self::permutations($this->data) as $permutation) {
            $this->permutations[] = $permutation;
        }
    }

    public function listPermutations()
    {
        var_dump($this->permutations);
    }
}