<?php

define('REWIND', 'doing rewind' . PHP_EOL);
define('NEXT', 'doing next' . PHP_EOL);
define('CURRENT', 'show current: ');
define('VALID', 'is valid: ');

$func = function() {
    echo '+ start' . PHP_EOL;
    $array = range(0, 2);
    
    foreach($array as $int) {
        echo '+ before yield' . PHP_EOL;
        yield $int;
        echo '+ after yield' . PHP_EOL;
    }
    echo '+ end' . PHP_EOL;
};

$generator = $func();

// processing like in a loop
echo REWIND;
$generator->rewind();
echo VALID;
echo '"' . $generator->valid() . '"' . PHP_EOL;
echo CURRENT;
echo '"' . $generator->current() . '"' . PHP_EOL;
echo NEXT;
$generator->next();
echo VALID;
echo '"' . $generator->valid() . '"' . PHP_EOL;
echo CURRENT;
echo '"' . $generator->current() . '"' . PHP_EOL;
echo NEXT;
$generator->next();
echo VALID;
echo '"' . $generator->valid() . '"' . PHP_EOL;
echo CURRENT;
echo '"' . $generator->current() . '"' . PHP_EOL;
echo NEXT;
$generator->next();
echo VALID;
echo '"' . $generator->valid() . '"' . PHP_EOL;

doing rewind
+ start
+ before yield
is valid: "1"
show current: "0"
doing next
+ after yield
+ before yield
is valid: "1"
show current: "1"
doing next
+ after yield
+ before yield
is valid: "1"
show current: "2"
doing next
+ after yield
+ end
is valid: ""

• Sort your data for each country individually
• Using SplHeap to order objects
• Introduced in PHP 7: call-method of closures

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