/**
* Applies callback to payload type if type is a collection
* The callback is applied before the collection calls its own logic
* on the current item. This allows you to prepare an item (change structure f.e.)
* so that the collection can translate the item to its type representation
*
* @param Payload $payload
* @param $callback
* @return \Prooph\Processing\Message\Payload
*/
public static function premap(Payload $payload, $callback)
{
$type = $payload->toType();
if ($type instanceof \OuterIterator) {
$payload->replaceType($type::fromNativeValue(new MapIterator($type->getInnerIterator(), $callback)));
}
return $payload;
}
