Creates a new deque using a callable to determine which values to include

# Ds\Deque::filter

(PECL ds >= 1.0.0)

Ds\Deque::filter — Creates a new deque using a callable to determine which values to include

### 説明

public Ds\Deque::filter ([ callable `$callback` ] ) : Ds\Deque

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

### パラメータ

`callback`

  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.

### 返り値

A new deque containing all the values for which either the `callback` returned `TRUE`, or all values that convert to `TRUE` if a `callback` was not provided.

### 例

例1 Ds\Deque::filter() example using callback function

`<?php
$deque = new \Ds\Deque([1, 2, 3, 4, 5]);
var_dump($deque->filter(function($value) {
return $value % 2 == 0;
}));
?>`

上の例の出力は、 たとえば以下のようになります。

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

例2 Ds\Deque::filter() example without a callback function

`<?php
$deque = new \Ds\Deque([0, 1, 'a', true, false]);
var_dump($deque->filter());
?>`

上の例の出力は、 たとえば以下のようになります。

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