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- <?php
- namespace Drupal\Component\Uuid;
- use Drupal\Component\Utility\Crypt;
- /**
- * Generates a UUID v4 (RFC 4122 section 4.4) using PHP code.
- *
- * @see http://www.rfc-editor.org/rfc/rfc4122.txt
- * @see http://www.rfc-editor.org/errata_search.php?rfc=4122&eid=3546
- */
- class Php implements UuidInterface {
- /**
- * {@inheritdoc}
- */
- public function generate() {
- // Obtain a random string of 32 hex characters.
- $hex = bin2hex(Crypt::randomBytes(16));
- // The variable names $time_low, $time_mid, $time_hi_and_version,
- // $clock_seq_hi_and_reserved, $clock_seq_low, and $node correlate to
- // the fields defined in RFC 4122 section 4.1.2.
- //
- // Use characters 0-11 to generate 32-bit $time_low and 16-bit $time_mid.
- $time_low = substr($hex, 0, 8);
- $time_mid = substr($hex, 8, 4);
- // Use characters 12-15 to generate 16-bit $time_hi_and_version.
- // The 4 most significant bits are the version number (0100 == 0x4).
- // We simply skip character 12 from $hex, and concatenate the strings.
- $time_hi_and_version = '4' . substr($hex, 13, 3);
- // Use characters 16-17 to generate 8-bit $clock_seq_hi_and_reserved.
- // The 2 most significant bits are set to one and zero respectively.
- $clock_seq_hi_and_reserved = base_convert(substr($hex, 16, 2), 16, 10);
- $clock_seq_hi_and_reserved &= 0b00111111;
- $clock_seq_hi_and_reserved |= 0b10000000;
- // Use characters 18-19 to generate 8-bit $clock_seq_low.
- $clock_seq_low = substr($hex, 18, 2);
- // Use characters 20-31 to generate 48-bit $node.
- $node = substr($hex, 20);
- // Re-combine as a UUID. $clock_seq_hi_and_reserved is still an integer.
- $uuid = sprintf('%s-%s-%s-%02x%s-%s',
- $time_low, $time_mid, $time_hi_and_version,
- $clock_seq_hi_and_reserved, $clock_seq_low,
- $node
- );
- return $uuid;
- }
- }
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