Guzzle iterators

Guzzle provides several SPL iterators that can be used with other SPL iterators, including Guzzle resource iterators. Guzzle's guzzle/iterator component can also be used independently of the rest of Guzzle through Packagist and Composer: https://packagist.org/packages/guzzle/iterator

ChunkedIterator

Pulls out multiple values from an inner iterator and yields and array of values for each outer iteration -- essentially pulling out chunks of values from the inner iterator.

use Guzzle\Iterator\ChunkedIterator;

$inner = new ArrayIterator(range(0, 8));
$chunkedIterator = new ChunkedIterator($inner, 2);

foreach ($chunkedIterator as $chunk) {
    echo implode(', ', $chunk) . "\n";
}

// >>> 0, 1
// >>> 2, 3
// >>> 4, 5
// >>> 6, 7
// >>> 8

FilterIterator

This iterator is used to filter values out of the inner iterator. This iterator can be used when PHP 5.4's CallbackFilterIterator is not available.

use Guzzle\Iterator\FilterIterator;

$inner = new ArrayIterator(range(1, 10));
$filterIterator = new FilterIterator($inner, function ($value) {
    return $value % 2;
});

foreach ($filterIterator as $value) {
    echo $value . "\n";
}

// >>> 2
// >>> 4
// >>> 6
// >>> 8
// >>> 10

MapIterator

This iterator modifies the values of the inner iterator before yielding.

use Guzzle\Iterator\MapIterator;

$inner = new ArrayIterator(range(0, 3));

$mapIterator = new MapIterator($inner, function ($value) {
    return $value * 10;
});

foreach ($mapIterator as $value) {
    echo $value . "\n";
}

// >>> 0
// >>> 10
// >>> 20
// >>> 30

MethodProxyIterator

This decorator is useful when you need to expose a specific method from an inner iterator that might be wrapper by one or more iterator decorators. This decorator proxies missing method calls to each inner iterator until one of the inner iterators can fulfill the call.

use Guzzle\Iterator\MethodProxyIterator;

$inner = new \ArrayIterator();
$proxy = new MethodProxyIterator($inner);

// Proxy method calls to the ArrayIterator
$proxy->append('a');
$proxy->append('b');