(PECL ds >= 1.0.0)
Ds\Map::filter — Creates a new map using a callable to determine which pairs to include
Creates a new map using a callable to determine which pairs to include.
callback
Optional callable which returns true if the pair should be included, false otherwise.
If a callback is not provided, only values which are true
(see converting to boolean)
will be included.
A new map containing all the pairs for which
either the callback returned true, or all values that
convert to true if a callback was not provided.
Example #1 Ds\Map::filter() example using callback function
<?php
$map = new \Ds\Map(["a", "b", "c", "d", "e"]);
var_dump($map->filter(function($key, $value) {
return $key % 2 == 0;
}));
?>
以上例程的输出类似于：
object(Ds\Map)#3 (3) {
[0]=>
object(Ds\Pair)#2 (2) {
["key"]=>
int(0)
["value"]=>
string(1) "a"
}
[1]=>
object(Ds\Pair)#4 (2) {
["key"]=>
int(2)
["value"]=>
string(1) "c"
}
[2]=>
object(Ds\Pair)#5 (2) {
["key"]=>
int(4)
["value"]=>
string(1) "e"
}
}
Example #2 Ds\Map::filter() example without a callback function
<?php
$map = new \Ds\Map(["a" => 0, "b" => 1, "c" => true, "d" => false]);
var_dump($map->filter());
?>
以上例程的输出类似于：
object(Ds\Map)#2 (3) {
[0]=>
int(1)
[1]=>
string(1) "a"
[2]=>
bool(true)
}