Online PHP editor | refs for sbaou

<?php function powerSet(Iterator $iterator){ if(!$iterator->valid()){ return yield new EmptyIterator(); } $one = $iterator->current(); $rest = new NoRewindIterator($iterator); $rest->next(); foreach(powerSet($rest) as $set){ $set = iterator_to_array($set); yield new ArrayIterator($set); yield (function($set, $one){ yield from $set; yield $one; })($set, $one); } } function baz(){ yield 1; yield 2; yield 3; yield 4; } $sets = powerSet(baz()); foreach($sets as $i => $set){ echo $i+1 . " {"; $arr = iterator_to_array($set); echo implode(", ", $arr); echo "}\n"; }