Ds\Map::filter
(PECL ds >= 1.0.0)
Ds\Map::filter — Creates a new map using a callable to determine which pairs to include
Description
public Ds\Map::filter(callable $callback = ?): Ds\Map
Creates a new map using a callable to determine which pairs to include.
Parameters
-
callback
-
callback(mixed $key, mixed $value): bool
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.
Return Values
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.
Examples
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; })); ?>
The above example will output something similar to:
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()); ?>
The above example will output something similar to:
object(Ds\Map)#2 (3) { [0]=> int(1) [1]=> string(1) "a" [2]=> bool(true) }
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https://www.php.net/manual/en/ds-map.filter.php