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<?php |
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/** |
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* Box packing (3D bin packing, knapsack problem). |
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* |
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* @author Doug Wright |
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*/ |
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declare(strict_types=1); |
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namespace DVDoug\BoxPacker; |
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use DVDoug\BoxPacker\Exception\NoBoxesAvailableException; |
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use Psr\Log\LoggerAwareInterface; |
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use Psr\Log\LoggerInterface; |
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use Psr\Log\LogLevel; |
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use Psr\Log\NullLogger; |
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use WeakMap; |
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use function array_pop; |
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use function count; |
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use function usort; |
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use const PHP_INT_MAX; |
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/** |
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* Actual packer. |
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*/ |
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class Packer implements LoggerAwareInterface |
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{ |
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private LoggerInterface $logger; |
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protected int $maxBoxesToBalanceWeight = 12; |
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protected ItemList $items; |
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protected BoxList $boxes; |
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/** |
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* @var WeakMap<Box, int> |
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*/ |
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protected WeakMap $boxQuantitiesAvailable; |
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protected PackedBoxSorter $packedBoxSorter; |
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protected bool $throwOnUnpackableItem = true; |
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private bool $beStrictAboutItemOrdering = false; |
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protected ?TimeoutChecker $timeoutChecker = null; |
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public function __construct() |
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{ |
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$this->items = new ItemList(); |
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$this->boxes = new BoxList(); |
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$this->packedBoxSorter = new DefaultPackedBoxSorter(); |
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$this->boxQuantitiesAvailable = new WeakMap(); |
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$this->logger = new NullLogger(); |
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} |
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public function setLogger(LoggerInterface $logger): void |
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{ |
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$this->logger = $logger; |
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} |
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/** |
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* Add item to be packed. |
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*/ |
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public function addItem(Item $item, int $qty = 1): void |
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{ |
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$this->items->insert($item, $qty); |
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$this->logger->log(LogLevel::INFO, "added {$qty} x {$item->getDescription()}", ['item' => $item]); |
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} |
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/** |
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* Set a list of items all at once. |
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* @param iterable<Item>|ItemList $items |
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*/ |
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public function setItems(iterable|ItemList $items): void |
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{ |
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if ($items instanceof ItemList) { |
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$this->items = clone $items; |
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} else { |
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$this->items = new ItemList(); |
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foreach ($items as $item) { |
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$this->items->insert($item); |
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} |
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} |
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} |
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/** |
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* Add box size. |
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*/ |
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public function addBox(Box $box): void |
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{ |
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$this->boxes->insert($box); |
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$this->setBoxQuantity($box, $box instanceof LimitedSupplyBox ? $box->getQuantityAvailable() : PHP_INT_MAX); |
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$this->logger->log(LogLevel::INFO, "added box {$box->getReference()}", ['box' => $box]); |
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} |
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/** |
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* Add a pre-prepared set of boxes all at once. |
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*/ |
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public function setBoxes(BoxList $boxList): void |
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{ |
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$this->boxes = $boxList; |
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foreach ($this->boxes as $box) { |
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$this->setBoxQuantity($box, $box instanceof LimitedSupplyBox ? $box->getQuantityAvailable() : PHP_INT_MAX); |
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} |
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} |
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/** |
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* Set the quantity of this box type available. |
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*/ |
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public function setBoxQuantity(Box $box, int $qty): void |
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{ |
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$this->boxQuantitiesAvailable[$box] = $qty; |
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} |
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/** |
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* Number of boxes at which balancing weight is deemed not worth the extra computation time. |
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*/ |
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public function getMaxBoxesToBalanceWeight(): int |
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{ |
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return $this->maxBoxesToBalanceWeight; |
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} |
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/** |
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* Number of boxes at which balancing weight is deemed not worth the extra computation time. |
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*/ |
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public function setMaxBoxesToBalanceWeight(int $maxBoxesToBalanceWeight): void |
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{ |
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$this->maxBoxesToBalanceWeight = $maxBoxesToBalanceWeight; |
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} |
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public function setPackedBoxSorter(PackedBoxSorter $packedBoxSorter): void |
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{ |
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$this->packedBoxSorter = $packedBoxSorter; |
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} |
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public function setTimeoutChecker(TimeoutChecker $timeoutChecker): void |
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{ |
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$this->timeoutChecker = $timeoutChecker; |
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} |
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public function throwOnUnpackableItem(bool $throwOnUnpackableItem): void |
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{ |
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$this->throwOnUnpackableItem = $throwOnUnpackableItem; |
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} |
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public function beStrictAboutItemOrdering(bool $beStrict): void |
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{ |
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$this->beStrictAboutItemOrdering = $beStrict; |
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} |
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/** |
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* Return the items that haven't been packed. |
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*/ |
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public function getUnpackedItems(): ItemList |
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{ |
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return $this->items; |
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} |
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/** |
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* Pack items into boxes using built-in heuristics for the best solution. |
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*/ |
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public function pack(): PackedBoxList |
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{ |
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$this->logger->log(LogLevel::INFO, '[PACKING STARTED]'); |
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$this->timeoutChecker?->start(); |
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$packedBoxes = $this->doBasicPacking(); |
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// If we have multiple boxes, try and optimise/even-out weight distribution |
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if (!$this->beStrictAboutItemOrdering && $packedBoxes->count() > 1 && $packedBoxes->count() <= $this->maxBoxesToBalanceWeight) { |
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$redistributor = new WeightRedistributor($this->boxes, $this->packedBoxSorter, $this->boxQuantitiesAvailable, $this->timeoutChecker); |
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$redistributor->setLogger($this->logger); |
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$packedBoxes = $redistributor->redistributeWeight($packedBoxes); |
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} |
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$this->logger->log(LogLevel::INFO, "[PACKING COMPLETED], {$packedBoxes->count()} boxes"); |
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return $packedBoxes; |
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} |
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/** |
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* @internal |
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*/ |
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public function doBasicPacking(bool $enforceSingleBox = false): PackedBoxList |
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{ |
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$packedBoxes = new PackedBoxList($this->packedBoxSorter); |
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// Keep going until everything packed |
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while ($this->items->count()) { |
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$packedBoxesIteration = []; |
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// Loop through boxes starting with smallest, see what happens |
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foreach ($this->getBoxList($enforceSingleBox) as $box) { |
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$this->timeoutChecker?->throwOnTimeout(); |
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$volumePacker = new VolumePacker($box, $this->items); |
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$volumePacker->setLogger($this->logger); |
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$volumePacker->beStrictAboutItemOrdering($this->beStrictAboutItemOrdering); |
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$packedBox = $volumePacker->pack(); |
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if ($packedBox->items->count()) { |
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$packedBoxesIteration[] = $packedBox; |
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// Have we found a single box that contains everything? |
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if ($packedBox->items->count() === $this->items->count()) { |
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$this->logger->log(LogLevel::DEBUG, "Single box found for remaining {$this->items->count()} items"); |
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break; |
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} |
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} |
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} |
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if (count($packedBoxesIteration) > 0) { |
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// Find best box of iteration, and remove packed items from unpacked list |
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usort($packedBoxesIteration, $this->packedBoxSorter->compare(...)); |
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$bestBox = $packedBoxesIteration[0]; |
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$this->items->removePackedItems($bestBox->items); |
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$packedBoxes->insert($bestBox); |
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--$this->boxQuantitiesAvailable[$bestBox->box]; |
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} elseif ($this->throwOnUnpackableItem) { |
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throw new NoBoxesAvailableException("No boxes could be found for item '{$this->items->top()->getDescription()}'", $this->items); |
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} else { |
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$this->logger->log(LogLevel::INFO, "{$this->items->count()} unpackable items found"); |
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break; |
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} |
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} |
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return $packedBoxes; |
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} |
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/** |
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* Pack items into boxes returning "all" possible box combination permutations. |
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* Use with caution (will be slow) with a large number of box types! |
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* |
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* @return PackedBoxList[] |
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*/ |
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public function packAllPermutations(): array |
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{ |
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$this->logger->log(LogLevel::INFO, '[PACKING STARTED (all permutations)]'); |
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$this->timeoutChecker?->start(); |
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$boxQuantitiesAvailable = clone $this->boxQuantitiesAvailable; |
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$wipPermutations = [['permutation' => new PackedBoxList($this->packedBoxSorter), 'itemsLeft' => $this->items]]; |
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$completedPermutations = []; |
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// Keep going until everything packed |
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while ($wipPermutations) { |
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$wipPermutation = array_pop($wipPermutations); |
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$remainingBoxQuantities = clone $boxQuantitiesAvailable; |
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foreach ($wipPermutation['permutation'] as $packedBox) { |
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--$remainingBoxQuantities[$packedBox->box]; |
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} |
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if ($wipPermutation['itemsLeft']->count() === 0) { |
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$completedPermutations[] = $wipPermutation['permutation']; |
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continue; |
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} |
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$additionalPermutationsForThisPermutation = []; |
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foreach ($this->boxes as $box) { |
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$this->timeoutChecker?->throwOnTimeout(); |
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if ($remainingBoxQuantities[$box] > 0) { |
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$volumePacker = new VolumePacker($box, $wipPermutation['itemsLeft']); |
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$volumePacker->setLogger($this->logger); |
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$packedBox = $volumePacker->pack(); |
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if ($packedBox->items->count()) { |
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$additionalPermutationsForThisPermutation[] = $packedBox; |
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} |
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} |
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} |
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if (count($additionalPermutationsForThisPermutation) > 0) { |
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foreach ($additionalPermutationsForThisPermutation as $additionalPermutationForThisPermutation) { |
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$newPermutation = clone $wipPermutation['permutation']; |
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$newPermutation->insert($additionalPermutationForThisPermutation); |
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$itemsRemainingOnPermutation = clone $wipPermutation['itemsLeft']; |
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$itemsRemainingOnPermutation->removePackedItems($additionalPermutationForThisPermutation->items); |
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$wipPermutations[] = ['permutation' => $newPermutation, 'itemsLeft' => $itemsRemainingOnPermutation]; |
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} |
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} elseif ($this->throwOnUnpackableItem) { |
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throw new NoBoxesAvailableException("No boxes could be found for item '{$wipPermutation['itemsLeft']->top()->getDescription()}'", $wipPermutation['itemsLeft']); |
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} else { |
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$this->logger->log(LogLevel::INFO, "{$this->items->count()} unpackable items found"); |
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if ($wipPermutation['permutation']->count() > 0) { // don't treat initial empty permutation as completed |
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$completedPermutations[] = $wipPermutation['permutation']; |
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} |
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} |
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} |
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$this->logger->log(LogLevel::INFO, '[PACKING COMPLETED], ' . count($completedPermutations) . ' permutations'); |
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foreach ($completedPermutations as $completedPermutation) { |
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foreach ($completedPermutation as $packedBox) { |
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$this->items->removePackedItems($packedBox->items); |
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} |
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} |
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return $completedPermutations; |
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} |
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/** |
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* Get a "smart" ordering of the boxes to try packing items into. The initial BoxList is already sorted in order |
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* so that the smallest boxes are evaluated first, but this means that time is spent on boxes that cannot possibly |
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* hold the entire set of items due to volume limitations. These should be evaluated first. |
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* |
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* @return iterable<Box> |
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*/ |
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protected function getBoxList(bool $enforceSingleBox = false): iterable |
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{ |
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$this->logger->log(LogLevel::INFO, 'Determining box search pattern', ['enforceSingleBox' => $enforceSingleBox]); |
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$itemVolume = 0; |
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foreach ($this->items as $item) { |
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$itemVolume += $item->getWidth() * $item->getLength() * $item->getDepth(); |
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} |
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$this->logger->log(LogLevel::DEBUG, 'Item volume', ['itemVolume' => $itemVolume]); |
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$preferredBoxes = []; |
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$otherBoxes = []; |
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foreach ($this->boxes as $box) { |
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if ($this->boxQuantitiesAvailable[$box] > 0) { |
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if ($box->getInnerWidth() * $box->getInnerLength() * $box->getInnerDepth() >= $itemVolume) { |
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$preferredBoxes[] = $box; |
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} elseif (!$enforceSingleBox) { |
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$otherBoxes[] = $box; |
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} |
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} |
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} |
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$this->logger->log(LogLevel::INFO, 'Box search pattern complete', ['preferredBoxCount' => count($preferredBoxes), 'otherBoxCount' => count($otherBoxes)]); |
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return [...$preferredBoxes, ...$otherBoxes]; |
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} |
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} |
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