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

Description

abstract public Ds\Sequence Ds\Sequence::filter ([ callable $callback ] )

Parameters

callback

bool callback ( mixed $value )

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)
}