[5.8] Arr::collapse better performance

[awais-vteams]

For large array to collapse() get better performance.

Ubuntu 14.04 Core™ i3-4130 CPU @ 3.40GHz × 4, 8GB

$arr = [];
for ($i = 0; $i < 20000; $i++) {
    $arr[] = [1, 2, 3];
}
Arr::collapse($arr);

Before: 6.88 s
After: 0.03 ms

[taylorotwell]

I don't get it... what is the purpose of merging two empty arrays at the end.

[awais-vteams]

I don't get it... what is the purpose of merging two empty arrays at the end.

without empty array, PHP 7.3 gives notice to array_merge() expect one parameter to be an array

[taylorotwell]

Is this actually the exact same behavior as the earlier array_merge logic?

[awais-vteams]

I don't get it But I believe this really time breaking performance in Arr::collapse function You can test run it.

[awais-vteams]

Actually, array_merge calling in loop previously having O(n) complexity but it now its O(1) 6x faster

[staudenmeir]

Do we need two empty arrays? array_merge([], ...$results) works for me.

[tantana5]

awesome, exactly i need