Generators & Iterators

Generators

function rangeGenerator(int \$start, int \$end): Generator {
    for (\$i = \$start; \$i <= \$end; \$i++) {
        yield \$i;
    }
}

foreach (rangeGenerator(1, 5) as \$num) {
    echo \$num; // 1 2 3 4 5
}

Key-Value Yield

function mapGenerator(array \$items): Generator {
    foreach (\$items as \$key => \$value) {
        yield \$key => strtoupper(\$value);
    }
}

Generator Delegation

function gen1(): Generator {
    yield 1;
    yield 2;
    yield from [3, 4, 5]; // delegate
    yield from gen2();    // delegate to another generator
}

IteratorAggregate

class MyCollection implements IteratorAggregate {
    public function __construct(private array \$items) {}
    public function getIterator(): Traversable {
        return new ArrayIterator(\$this->items);
    }
}