iterator-vs-generator.php

<?php
 
// iterator impl:
 
class MapIterator extends IteratorIterator {
    private $f;
 
    public function __construct($f, $inner) {
        parent::__construct($inner);
        $this->f = $f;
    }
 
    function current() {
        return call_user_func($this->f, parent::current());
    }
}
 
function iter_map($f, $iter) {
    return new MapIterator($f, $iter);
}
 
// generator impl:
 
function gen_map($f, $iter) {
    foreach ($iter as $k => $v) {
        yield $k => $f($v);
    }
}
 
// example:
 
function times_two($x) {
    return $x * 2;
}
 
$source = new ArrayIterator([0, 1, 2, 3, 4, 5, 6]);
 
var_dump(iterator_to_array(iter_map('times_two', $source)));
var_dump(iterator_to_array(gen_map('times_two', $source)));