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<?php
/**
* This file is part of the ramsey/uuid library
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*
* @copyright Copyright (c) Ben Ramsey <ben@benramsey.com>
* @license http://opensource.org/licenses/MIT MIT
*/
declare(strict_types=1);
namespace Ramsey\Uuid\Rfc4122;
use Ramsey\Uuid\Exception\InvalidBytesException;
use Ramsey\Uuid\Uuid;
use function decbin;
use function str_pad;
use function str_starts_with;
use function strlen;
use function substr;
use function unpack;
use const STR_PAD_LEFT;
/**
* Provides common functionality for handling the variant, as defined by RFC 9562 (formerly RFC 4122)
*
* @immutable
*/
trait VariantTrait
{
/**
* Returns the bytes that comprise the fields
*/
abstract public function getBytes(): string;
/**
* Returns the variant
*
* The variant number describes the layout of the UUID. The variant number has the following meaning:
*
* - 0 - Reserved for NCS backward compatibility
* - 2 - The RFC 9562 (formerly RFC 4122) variant
* - 6 - Reserved, Microsoft Corporation backward compatibility
* - 7 - Reserved for future definition
*
* For RFC 9562 (formerly RFC 4122) variant UUIDs, this value should always be the integer `2`.
*
* @link https://www.rfc-editor.org/rfc/rfc9562#section-4.1 RFC 9562, 4.1. Variant Field
*/
public function getVariant(): int
{
if (strlen($this->getBytes()) !== 16) {
throw new InvalidBytesException('Invalid number of bytes');
}
// According to RFC 9562, sections {@link https://www.rfc-editor.org/rfc/rfc9562#section-4.1 4.1} and
// {@link https://www.rfc-editor.org/rfc/rfc9562#section-5.10 5.10}, the Max UUID falls within the range
// of the future variant.
if ($this->isMax()) {
return Uuid::RESERVED_FUTURE;
}
// According to RFC 9562, sections {@link https://www.rfc-editor.org/rfc/rfc9562#section-4.1 4.1} and
// {@link https://www.rfc-editor.org/rfc/rfc9562#section-5.9 5.9}, the Nil UUID falls within the range
// of the Apollo NCS variant.
if ($this->isNil()) {
return Uuid::RESERVED_NCS;
}
/** @var int[] $parts */
$parts = unpack('n*', $this->getBytes());
// $parts[5] is a 16-bit, unsigned integer containing the variant bits of the UUID. We convert this integer into
// a string containing a binary representation, padded to 16 characters. We analyze the first three characters
// (three most-significant bits) to determine the variant.
$msb = substr(str_pad(decbin($parts[5]), 16, '0', STR_PAD_LEFT), 0, 3);
if ($msb === '111') {
return Uuid::RESERVED_FUTURE;
} elseif ($msb === '110') {
return Uuid::RESERVED_MICROSOFT;
} elseif (str_starts_with($msb, '10')) {
return Uuid::RFC_4122;
}
return Uuid::RESERVED_NCS;
}
}
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