gistfile1.php

<?php

function iterator_chunk($iterable, $size, $preserve_keys = false)
{
    $chunk = [];

    foreach ($iterable as $key => $value) {
        if ($preserve_keys) {
            $chunk[$key] = $value;
        } else {
            $chunk[] = $value;
        }

        if (\count($chunk) === $size) {
            yield $chunk;
            $chunk = [];
        }
    }
}

function iterator_column($iterable, $column_key, $index_key = null)
{
    if ($index_key === null) {
        foreach ($iterable as $value) {
            yield $value[$column_key];
        }
    } else {
        foreach ($iterable as $value) {
            yield $value[$index_key] => $value[$column_key];
        }
    }
}

function iterator_combine($keys, $values)
{
    foreach ($values as $value) {
        yield $keys->current() => $value;
        $keys->next();
    }
}

function iterator_count_values($iterable)
{
    $values = [];

    foreach ($iterable as $value) {
        if (empty($values[$value])) {
            $values[$value] = 0;
        }
        $values[$value]++;
    }

    return $values;
}

function iterator_flip($iterable)
{
    foreach ($iterable as $key => $value) {
        yield $value => $key;
    }
}

function count($iterable)
{
    $count = 0;
    
    foreach ($iterable as $_) {
        $count++;
    }
    
    return $count;
}