Ds\Sequence::filter

(PECL ds >= 1.0.0)

Ds\Sequence::filter — Creates a new sequence using a callable to determine which values to include

Description

abstract public function Ds\Sequence::filter(callable $callback = ?): Ds\Sequence

Creates a new sequence using a callable to determine which values to include.

Parameters

callback

function callback(mixed $value): bool

Optional callable which returns true if the value 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 sequence containing all the values for which either the callback returned true, or all values that convert to true if a callback was not provided.

Examples

Example #1 Ds\Sequence::filter() example using callback function

<?php
$sequence = new \Ds\Vector([1, 2, 3, 4, 5]);

var_dump($sequence->filter(function($value) {
    return $value % 2 == 0;
}));
?>

The above example will output something similar to:

object(Ds\Vector)#3 (2) {
  [0]=>
  int(2)
  [1]=>
  int(4)
}

Example #2 Ds\Sequence::filter() example without a callback function

<?php
$sequence = new \Ds\Vector([0, 1, 'a', true, false]);

var_dump($sequence->filter());
?>

The above example will output something similar to:

object(Ds\Vector)#2 (3) {
  [0]=>
  int(1)
  [1]=>
  string(1) "a"
  [2]=>
  bool(true)
}