How to use bitsets

Bitsets are used to handle boolean flags efficiently.

The class \TYPO3\CMS\Core\Type\BitSet provides a TYPO3 implementation of a bitset. It can be used standalone and accessed from the outside, but we recommend creating specific bitset classes that extend the TYPO3 BitSet class.

The functionality is best described by an example:

<?php

declare(strict_types=1);

use TYPO3\CMS\Core\Type\BitSet;

define('PERMISSIONS_NONE', 0b0); // 0
define('PERMISSIONS_PAGE_SHOW', 0b1); // 1
define('PERMISSIONS_PAGE_EDIT', 0b10); // 2
define('PERMISSIONS_PAGE_DELETE', 0b100); // 4
define('PERMISSIONS_PAGE_NEW', 0b1000); // 8
define('PERMISSIONS_CONTENT_EDIT', 0b10000); // 16
define('PERMISSIONS_ALL', 0b11111); // 31

$bitSet = new BitSet(PERMISSIONS_PAGE_SHOW | PERMISSIONS_PAGE_NEW);
$bitSet->get(PERMISSIONS_PAGE_SHOW); // true
$bitSet->get(PERMISSIONS_CONTENT_EDIT); // false
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The example above uses global constants. Implementing that via an extended bitset class makes it clearer and easier to use:

EXT:my_extension/Classes/Bitmask/Permissions.php 
<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Bitmask;

use TYPO3\CMS\Core\Type\BitSet;

final class Permissions extends BitSet
{
    public const NONE = 0b0; // 0
    public const PAGE_SHOW = 0b1; // 1
    public const PAGE_EDIT = 0b10; // 2
    public const PAGE_DELETE = 0b100; // 4
    public const PAGE_NEW = 0b1000; // 8
    public const CONTENT_EDIT = 0b10000; // 16
    public const ALL = 0b11111; // 31

    public function hasPermission(int $permission): bool
    {
        return $this->get($permission);
    }

    public function hasAllPermissions(): bool
    {
        return $this->get(self::ALL);
    }

    public function allow(int $permission): void
    {
        $this->set($permission);
    }
}
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Then use your custom bitset class:

<?php

declare(strict_types=1);

use MyVendor\MyExtension\Bitmask\Permissions;

$permissions = new Permissions(Permissions::PAGE_SHOW | Permissions::PAGE_NEW);
$permissions->hasPermission(Permissions::PAGE_SHOW); // true
$permissions->hasPermission(Permissions::CONTENT_EDIT); // false
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