/**
* Helper method to perform actual mapping
* @param array|\Traversable $inner
* @param array|\Traversable $outer
* @param callable $callable
*/
private function mapOn($inner, $outer, callable $callable)
{
$this->innerGroup = [];
foreach ($outer as $k => $o) {
$group = new qinq\Collection();
foreach ($inner as $i) {
$check = $callable($o, $i);
if ($check === true) {
$group->add($i);
}
}
$this->innerGroup[$k] = $group;
}
}
