<?php

$i = new ArrayIterator(array(1,7,9,null,40,'dude',3));

$filtered = new RegexIterator($i, '/\d+/');

foreach($filtered as $value) {
    echo $value . PHP_EOL;
}

1
7
9
40
3

• Get a list of all possible transliterations
• PHP's own queue class: SplQueue
• Create a queue with value-priorities

PHP 8.3, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8