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<?php |
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declare(strict_types=1); |
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namespace Doctrine\ODM\MongoDB\Iterator; |
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use Generator; |
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use RuntimeException; |
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use Traversable; |
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use function current; |
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use function key; |
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use function next; |
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use function reset; |
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/** |
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* Iterator for wrapping a Traversable and caching its results. |
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* |
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* By caching results, this iterators allows a Traversable to be counted and |
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* rewound multiple times, even if the wrapped object does not natively support |
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* those operations (e.g. MongoDB\Driver\Cursor). |
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* |
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* @internal |
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*/ |
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final class CachingIterator implements Iterator |
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{ |
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/** @var array */ |
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private $items = []; |
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/** @var Generator|null */ |
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private $iterator; |
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/** @var bool */ |
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private $iteratorAdvanced = false; |
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/** @var bool */ |
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private $iteratorExhausted = false; |
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/** |
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* Initialize the iterator and stores the first item in the cache. This |
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* effectively rewinds the Traversable and the wrapping Generator, which |
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* will execute up to its first yield statement. Additionally, this mimics |
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* behavior of the SPL iterators and allows users to omit an explicit call |
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* to rewind() before using the other methods. |
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*/ |
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public function __construct(Traversable $iterator) |
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{ |
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$this->iterator = $this->wrapTraversable($iterator); |
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$this->storeCurrentItem(); |
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} |
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public function __destruct() |
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{ |
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$this->iterator = null; |
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} |
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public function toArray() : array |
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{ |
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$this->exhaustIterator(); |
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return $this->items; |
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} |
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/** |
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* @see http://php.net/iterator.current |
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* |
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* @return mixed |
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*/ |
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public function current() |
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{ |
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return current($this->items); |
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} |
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/** |
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* @see http://php.net/iterator.mixed |
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* |
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* @return mixed |
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*/ |
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public function key() |
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{ |
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return key($this->items); |
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} |
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/** |
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* @see http://php.net/iterator.next |
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*/ |
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public function next() : void |
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{ |
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if (! $this->iteratorExhausted) { |
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$this->getIterator()->next(); |
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$this->storeCurrentItem(); |
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} |
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next($this->items); |
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} |
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/** |
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* @see http://php.net/iterator.rewind |
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*/ |
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public function rewind() : void |
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{ |
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/* If the iterator has advanced, exhaust it now so that future iteration |
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* can rely on the cache. |
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*/ |
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if ($this->iteratorAdvanced) { |
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$this->exhaustIterator(); |
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} |
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reset($this->items); |
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} |
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/** |
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* @see http://php.net/iterator.valid |
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*/ |
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public function valid() : bool |
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{ |
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return $this->key() !== null; |
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} |
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/** |
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* Ensures that the inner iterator is fully consumed and cached. |
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*/ |
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private function exhaustIterator() : void |
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{ |
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while (! $this->iteratorExhausted) { |
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$this->next(); |
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} |
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$this->iterator = null; |
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} |
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private function getIterator() : Generator |
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{ |
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if ($this->iterator === null) { |
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throw new RuntimeException('Iterator has already been destroyed'); |
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} |
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return $this->iterator; |
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} |
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/** |
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* Stores the current item in the cache. |
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*/ |
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private function storeCurrentItem() : void |
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{ |
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$key = $this->getIterator()->key(); |
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if ($key === null) { |
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return; |
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} |
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$this->items[$key] = $this->getIterator()->current(); |
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} |
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private function wrapTraversable(Traversable $traversable) : Generator |
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{ |
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foreach ($traversable as $key => $value) { |
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yield $key => $value; |
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$this->iteratorAdvanced = true; |
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} |
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$this->iteratorExhausted = true; |
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} |
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} |
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