gnu-social/src/Util/Functional.php

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<?php
declare(strict_types = 1);
// {{{ License
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social. If not, see <http://www.gnu.org/licenses/>.
// }}}
/**
* String formatting utilities
*
* @package GNUsocial
* @category Util
*
* @author Hugo Sales <hugo@hsal.es>
* @copyright 2020-2021 Free Software Foundation, Inc http://www.fsf.org
* @license https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
*/
namespace App\Util;
use Stringable;
abstract class Functional
{
/**
* TODO replace with \Functional\cartesian_product when it gets merged upstream
*
* @param array<array<string|Stringable>> $collections
*/
public static function cartesianProduct(array $collections, string|array $separator = ''): array
{
$aggregation = [];
$left = array_shift($collections);
while (true) {
$right = array_shift($collections);
foreach ($left as $l) {
foreach ($right as $r) {
if (\is_string($separator)) {
$aggregation[] = "{$l}{$separator}{$r}";
} elseif (\is_array($separator)) {
foreach ($separator as $sep) {
$aggregation[] = "{$l}{$sep}{$r}";
}
}
}
}
if (empty($collections)) {
break;
} else {
$left = $aggregation;
$aggregation = [];
}
}
return $aggregation;
}
}