Ds\Deque::map

(PECL ds >= 1.0.0)

Ds\Deque::map — Returns the result of applying a callback to each value

public Ds\Deque::map(callable $callback): Ds\Deque

Returns the result of applying a callback function to each value in the deque.

callback

callback(mixed $value): mixed

A callable to apply to each value in the deque.

The callable should return what the new value will be in the new deque.

The result of applying a callback to each value in the deque.

注意:
The values of the current instance won't be affected.

示例 #1 Ds\Deque::map() example

<?php
$deque = new \Ds\Deque([1, 2, 3]);

print_r($deque->map(function($value) { return $value * 2; }));
print_r($deque);
?>

以上示例的输出类似于：

Ds\Deque Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)
Ds\Deque Object
(
    [0] => 1
    [1] => 2
    [2] => 3
)