Re: [PHP-DEV] Feature request and RFC

[Rowan Collins]

On 08/03/2015 15:45, Grégory Planchat wrote:
class BarSortable implements Sorter
{
    public function sort(Sortable $collection)
    {
        $previousKey = null;
        $previousElement = null;
        foreach ($collection as $key => $element) {
            if ($previousKey === null) {
                $previousKey = $key;
                $previousElement = $element;
                continue;
            }
            if ($previousElement < element) {
                $collection->swap($previousKey, $key);
            }

            $previousKey = $key;
            $previousElement = $element;
        }
    }
}

Unfortunately, this won't actually sort the array - it only makes one 
check of each value, so [4, 1, 2, 3, 5] would come out as [4, 2, 3, 1, 
5], when it should be [5, 4, 3, 2, 1] (your < sign means you're sorting 
largest value first). It's *almost* like a bubble sort, though (you keep 
swapping things until you know that there's no more swaps to be made), 
which is the simplest but also least efficient way of sorting a list.

I think insertion sort, which is simple and efficient for small lists, 
could be done with iteration plus a single callback of 
"insertElementAt". For larger lists, though, you're going to want a 
quicksort, and I can't quite picture what callbacks that would need to 
run on the collection as it went; it ultimately requires some way of 
partitioning the list into multiple pieces.

Regards,

--
Rowan Collins
[IMSoP]


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