Returns the result of applying a callback to each value

说明

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

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

参数

callback

mixed callback ( mixed $key , mixed $value )

A callable to apply to each value in the map.

The callable should return what the key will be mapped to in the resulting map.

返回值

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

Note:
The keys and values of the current instance won't be affected.

范例

Example #1 Ds\Map::map() example


<?php
$map = new \Ds\Map(["a" => 1, "b" => 2, "c" => 3]);

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

以上例程的输出类似于：

(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 2
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 4
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 6
        )

)
Ds\Map Object
(
    [0] => Ds\Pair Object
        (
            [key] => a
            [value] => 1
        )

    [1] => Ds\Pair Object
        (
            [key] => b
            [value] => 2
        )

    [2] => Ds\Pair Object
        (
            [key] => c
            [value] => 3
        )

)