(PECL ds >= 1.2.7)
Ds\Set::map — Returns the result of applying a callback to each value
Returns the result of applying a callback function to
each value in the set.
callbackThe callback to apply to each value in the set must have the following signature:
Returns a new Ds\Set instance where each value
is the result of applying the callback to each value
of the set.
示例 #1 Ds\Set::map() example
<?php
$set = new \Ds\Set([1, 2, 3]);
var_dump($set->map(function($value) { return $value * 2; }));
var_dump($set);
?>以上示例的输出类似于：
object(Ds\Set)#3 (3) {
[0]=>
int(2)
[1]=>
int(4)
[2]=>
int(6)
}
object(Ds\Set)#1 (3) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
int(3)
}