# Ds\Deque::map

(PECL ds >= 1.0.0)

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

### Description

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

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

### Parameters

`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.

### Return Values

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

> Note:

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

### Examples

Example #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);
?>`

The above example will output something similar to:

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