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<?php |
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namespace RayRutjes\GetEventStore\Client\Http\Feed; |
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use RayRutjes\GetEventStore\Client\Http\HttpClient; |
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use RayRutjes\GetEventStore\Client\Http\ReadEventStreamFeedRequestFactory; |
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use RayRutjes\GetEventStore\Client\Http\ReadEventStreamFeedResponseInspector; |
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use RayRutjes\GetEventStore\ReadDirection; |
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use RayRutjes\GetEventStore\StreamId; |
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class EventStreamFeedIterator implements \Iterator |
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{ |
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/** |
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* @var StreamId |
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*/ |
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private $streamId; |
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/** |
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* @var HttpClient |
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*/ |
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private $client; |
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/** |
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* @var EventStreamFeed |
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*/ |
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private $currentFeed; |
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/** |
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* @var string |
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*/ |
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private $headUri; |
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/** |
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* @var string |
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*/ |
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private $startUri; |
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/** |
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* @var ReadDirection |
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*/ |
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private $readDirection; |
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/** |
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* @var bool |
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*/ |
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private $initialized = false; |
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/** |
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* @var int |
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*/ |
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private $currentKey = 0; |
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/** |
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* You can either iterate reading from the start of the stream, beginning at the first event registered and move forward, |
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* or you can iterate from the end, meaning that the first iteration will correspond to the latest event registered, |
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* and move backward to the beginning of the stream. |
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* |
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* @param StreamId $streamId |
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* @param HttpClient $client |
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* @param bool $readFromStart |
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*/ |
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public function __construct(StreamId $streamId, HttpClient $client, $readFromStart = true) |
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{ |
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$this->streamId = $streamId; |
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$this->client = $client; |
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$this->headUri = sprintf('streams/%s', $streamId->toString()); |
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$direction = $readFromStart ? ReadDirection::FORWARD : ReadDirection::BACKWARD; |
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$this->readDirection = new ReadDirection($direction); |
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} |
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/** |
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* @param string $uri |
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* |
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* @return EventStreamFeed |
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*/ |
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private function readEventStreamFeed(string $uri): EventStreamFeed |
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{ |
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$factory = new ReadEventStreamFeedRequestFactory($uri); |
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$inspector = new ReadEventStreamFeedResponseInspector(); |
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$this->client->send($factory->buildRequest(), $inspector); |
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return $inspector->getFeed(); |
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} |
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/** |
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* @return EventStreamFeed |
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*/ |
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public function current(): EventStreamFeed |
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{ |
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if (null === $this->currentFeed) { |
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if (true === $this->initialized) { |
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throw new \OutOfBoundsException('Stream overflow.'); |
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} else { |
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$this->rewind(); |
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} |
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} |
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return $this->currentFeed; |
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} |
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public function next() |
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{ |
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$this->currentKey++; |
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if ($this->readDirection->isForward()) { |
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return $this->readForward(); |
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} |
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$this->readBackward(); |
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} |
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private function readForward() |
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{ |
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if ($this->currentFeed->hasPreviousLink() && !$this->currentFeed->isHeadOfStream()) { |
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$this->currentFeed = $this->readEventStreamFeed($this->currentFeed->getPreviousLink()->getUri()); |
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return; |
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} |
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$this->currentFeed = null; |
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} |
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private function readBackward() |
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{ |
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if ($this->currentFeed->hasNextLink()) { |
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$this->currentFeed = $this->readEventStreamFeed($this->currentFeed->getNextLink()->getUri()); |
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return; |
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} |
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$this->currentFeed = null; |
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} |
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/** |
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* @return int |
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*/ |
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public function key(): int |
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{ |
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return $this->currentKey; |
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} |
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/** |
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* @return bool |
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*/ |
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public function valid(): bool |
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{ |
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return null !== $this->currentFeed; |
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} |
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public function rewind() |
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{ |
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$this->currentKey = 0; |
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if ($this->readDirection->isForward()) { |
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$this->startUri = $this->getStartUri(); |
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$this->currentFeed = $this->readEventStreamFeed($this->startUri); |
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} else { |
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$this->currentFeed = $this->readEventStreamFeed($this->headUri); |
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} |
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$this->initialized = true; |
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// Todo: not sure how we should handle errors here. |
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// Todo: for now, let it bubble. |
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} |
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/** |
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* @return string |
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*/ |
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private function getStartUri(): string |
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{ |
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if (null !== $this->startUri) { |
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return $this->startUri; |
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} |
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// It is recommended to not guess the uris for backward compatibility. |
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// So we have to make an intermediary request to get the start uri. |
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$feed = $this->readEventStreamFeed($this->headUri); |
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if ($feed->hasLastLink()) { |
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return $feed->getLastLink()->getUri(); |
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} |
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// If we came so far it means we are dealing with a feed of exactly one page. |
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// So head = start. |
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return $this->headUri; |
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} |
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/** |
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* @return ReadDirection |
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*/ |
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public function getReadDirection() |
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{ |
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return $this->readDirection; |
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} |
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} |
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