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<?php |
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declare( strict_types = 1 ); |
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namespace BatchingIterator; |
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use InvalidArgumentException; |
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/** |
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* Iterator that batches calls for additional values. |
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* |
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* This is useful as a foundation for iterators over data that is |
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* in an expensive to access location, such as a database or a web API. |
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* |
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* @since 1.0 |
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* |
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* @licence GNU GPL v2+ |
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* @author Jeroen De Dauw < [email protected] > |
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*/ |
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class BatchingIterator implements \Iterator { |
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/** |
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* @var BatchingFetcher |
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*/ |
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private $fetcher; |
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/** |
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* @var int |
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*/ |
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private $maxBatchSize = 10; |
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/** |
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* @var mixed|null |
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*/ |
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private $current = null; |
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/** |
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* @var mixed[] |
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*/ |
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private $currentBatch = []; |
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/** |
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* @var int |
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*/ |
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private $key; |
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public function __construct( BatchingFetcher $fetcher ) { |
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$this->fetcher = $fetcher; |
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} |
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/** |
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* @param int $maxBatchSize |
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* |
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* @throws InvalidArgumentException |
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*/ |
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public function setMaxBatchSize( int $maxBatchSize ) { |
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if ( $maxBatchSize < 1 ) { |
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throw new InvalidArgumentException( '$maxBatchSize should be an int bigger than 0.' ); |
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} |
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$this->maxBatchSize = $maxBatchSize; |
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} |
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/** |
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* Returns a value of the type returned by the BatchingFetcher, |
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* or null if there are no further values. |
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* |
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* @return mixed|null |
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*/ |
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public function current() { |
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return $this->current; |
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} |
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public function next() { |
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$value = array_shift( $this->currentBatch ); |
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if ( $value === null ) { |
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$this->nextValueFromNewBatch(); |
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} |
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else { |
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$this->current = $value; |
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$this->key++; |
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} |
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} |
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private function nextValueFromNewBatch() { |
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$this->currentBatch = $this->fetcher->fetchNext( $this->maxBatchSize ); |
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if ( empty( $this->currentBatch ) ) { |
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$this->current = null; |
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} |
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else { |
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$this->next(); |
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} |
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} |
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public function key(): int { |
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return $this->key; |
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} |
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public function valid(): bool { |
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return $this->current !== null; |
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} |
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public function rewind() { |
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$this->fetcher->rewind(); |
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$this->key = -1; |
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$this->next(); |
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} |
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} |
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JeroenDeDauw /
BatchingIterator
