PHP Manual: Updates all values by applying a callback function to each value

public void Ds\Deque::apply(callable $callback)

Updates all values by applying a callback function to each value in the deque.

callback

mixed callback(mixed $value)

A callable to apply to each value in the deque.

The callback should return what the value should be replaced by.

No value is returned.

Example #1 Ds\Deque::apply example

<?php
$deque = new \Ds\Deque([1, 2, 3]);
$deque->apply(function($value) { return $value * 2; });

print_r($deque);
?>

The above example will output something similar to:

Ds\Deque Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)