Viewing file:  CursorBasedIterator.php (4.57 KB) -rw-r--r--
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<?php
/*
* This file is part of the Predis package.
*
* (c) 2009-2020 Daniele Alessandri
* (c) 2021-2025 Till Krüss
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Predis\Collection\Iterator;
use Iterator;
use Predis\ClientInterface;
use Predis\NotSupportedException;
use ReturnTypeWillChange;
/**
* Provides the base implementation for a fully-rewindable PHP iterator that can
* incrementally iterate over cursor-based collections stored on Redis using the
* commands in the `SCAN` family.
*
* Given their incremental nature with multiple fetches, these kind of iterators
* offer limited guarantees about the returned elements because the collection
* can change several times during the iteration process.
*
* @see http://redis.io/commands/scan
*/
abstract class CursorBasedIterator implements Iterator
{
protected $client;
protected $match;
protected $count;
protected $valid;
protected $fetchmore;
protected $elements;
protected $cursor;
protected $position;
protected $current;
/**
* @param ClientInterface $client Client connected to Redis.
* @param string $match Pattern to match during the server-side iteration.
* @param int $count Hint used by Redis to compute the number of results per iteration.
*/
public function __construct(ClientInterface $client, $match = null, $count = null)
{
$this->client = $client;
$this->match = $match;
$this->count = $count;
$this->reset();
}
/**
* Ensures that the client supports the specified Redis command required to
* fetch elements from the server to perform the iteration.
*
* @param ClientInterface $client Client connected to Redis.
* @param string $commandID Command ID.
*
* @throws NotSupportedException
*/
protected function requiredCommand(ClientInterface $client, $commandID)
{
if (!$client->getCommandFactory()->supports($commandID)) {
throw new NotSupportedException("'$commandID' is not supported by the current command factory.");
}
}
/**
* Resets the inner state of the iterator.
*/
protected function reset()
{
$this->valid = true;
$this->fetchmore = true;
$this->elements = [];
$this->cursor = 0;
$this->position = -1;
$this->current = null;
}
/**
* Returns an array of options for the `SCAN` command.
*
* @return array
*/
protected function getScanOptions()
{
$options = [];
if (strlen(strval($this->match)) > 0) {
$options['MATCH'] = $this->match;
}
if ($this->count > 0) {
$options['COUNT'] = $this->count;
}
return $options;
}
/**
* Fetches a new set of elements from the remote collection, effectively
* advancing the iteration process.
*
* @return array
*/
abstract protected function executeCommand();
/**
* Populates the local buffer of elements fetched from the server during
* the iteration.
*/
protected function fetch()
{
[$cursor, $elements] = $this->executeCommand();
if (!$cursor) {
$this->fetchmore = false;
}
$this->cursor = $cursor;
$this->elements = $elements;
}
/**
* Extracts next values for key() and current().
*/
protected function extractNext()
{
++$this->position;
$this->current = array_shift($this->elements);
}
/**
* @return void
*/
#[ReturnTypeWillChange]
public function rewind()
{
$this->reset();
$this->next();
}
/**
* @return mixed
*/
#[ReturnTypeWillChange]
public function current()
{
return $this->current;
}
/**
* @return int|null
*/
#[ReturnTypeWillChange]
public function key()
{
return $this->position;
}
/**
* @return void
*/
#[ReturnTypeWillChange]
public function next()
{
tryFetch:
if (!$this->elements && $this->fetchmore) {
$this->fetch();
}
if ($this->elements) {
$this->extractNext();
} elseif ($this->cursor) {
goto tryFetch;
} else {
$this->valid = false;
}
}
/**
* @return bool
*/
#[ReturnTypeWillChange]
public function valid()
{
return $this->valid;
}
}
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