 
 
 
 
 
 , (*1)
, (*1)
FlattenIterator
Flattens arrays and / or traversables. Accepts any iterable composed of iterables., (*2)
PHP 7.1+, (*3)
Usage
use BenTools\FlattenIterator\FlattenIterator;
require_once __DIR__ . '/vendor/autoload.php';
$cities = [
    [
        'london' => 'London',
        'paris' => 'Paris',
    ],
    new \ArrayIterator([
        'berlin' => 'Berlin',
        'bruxelles' => 'Bruxelles',
    ]),
    (function () {
        yield 'budapest' => 'Budapest';
        yield 'prague' => 'Prague';
    })(),
];
foreach (new FlattenIterator($cities) as $city) {
    var_dump($city);
}
Output:, (*4)
string(6) "London"
string(5) "Paris"
string(6) "Berlin"
string(9) "Bruxelles"
string(8) "Budapest"
string(6) "Prague"
Array output and fluent interface
You can use the built-in function to generate your flattened data, and export them as an array:, (*5)
use function BenTools\FlattenIterator\flatten;
print_r(flatten($cities)->asArray());
Output:, (*6)
array(6) {
  [0]=>
  string(6) "London"
  [1]=>
  string(5) "Paris"
  [2]=>
  string(6) "Berlin"
  [3]=>
  string(9) "Bruxelles"
  [4]=>
  string(8) "Budapest"
  [5]=>
  string(6) "Prague"
}
Preserve Keys
Set $preserveKeys to true to preserve keys in your flattened data:, (*7)
var_dump(flatten($cities, $preserveKeys = true)->asArray());
Output:, (*8)
array(6) {
  ["london"]=>
  string(6) "London"
  ["paris"]=>
  string(5) "Paris"
  ["berlin"]=>
  string(6) "Berlin"
  ["bruxelles"]=>
  string(9) "Bruxelles"
  ["budapest"]=>
  string(8) "Budapest"
  ["prague"]=>
  string(6) "Prague"
}
Installation
composer require bentools/flatten-iterator
Unit tests
./vendor/bin/phpunit
See also
bentools/cartesian-product, (*9)
bentools/string-combinations, (*10)
bentools/iterable-functions, (*11)