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<?php |
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declare(strict_types=1); |
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namespace drupol\phpermutations\Iterators; |
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use drupol\phpermutations\Iterators; |
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use function array_slice; |
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use function count; |
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class Shift extends Iterators |
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{ |
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/** |
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* Shift constructor. |
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* |
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* @param array<int, mixed> $dataset |
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* The dataset |
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* @param int $length |
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* The shift length |
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*/ |
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public function __construct(array $dataset = [], $length = 1) |
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{ |
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parent::__construct($dataset, $length); |
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$this->current = $this->getDataset(); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function count(): int |
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{ |
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return count($this->getDataset()); |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* @return void |
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*/ |
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public function next(): void |
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{ |
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$this->doShift(1); |
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} |
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/** |
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* {@inheritdoc} |
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*/ |
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public function rewind(): void |
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{ |
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$this->doShift(-1); |
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} |
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/** |
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* {@inheritdoc} |
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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 true; |
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} |
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/** |
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* Internal function to do the shift. |
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* |
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* @param int $length |
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* |
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* @return void |
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*/ |
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protected function doShift($length = 1): void |
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{ |
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$parameters = []; |
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if (0 > $length) { |
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$parameters[] = ['start' => abs($length), 'end' => null]; |
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$parameters[] = ['start' => 0, 'end' => abs($length)]; |
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} else { |
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$parameters[] = ['start' => -1 * $length, 'end' => null]; |
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$parameters[] = ['start' => 0, 'end' => $this->datasetCount + $length * -1]; |
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} |
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$this->current = array_merge( |
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array_slice($this->current, $parameters[0]['start'], $parameters[0]['end']), |
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array_slice($this->current, $parameters[1]['start'], $parameters[1]['end']) |
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); |
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} |
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} |
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drupol /
phpermutations
