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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 function count; |
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use function max; |
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use function min; |
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use Psr\Log\LoggerAwareInterface; |
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use Psr\Log\LoggerInterface; |
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use Psr\Log\NullLogger; |
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/** |
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* Actual packer. |
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* |
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* @author Doug Wright |
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*/ |
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class VolumePacker implements LoggerAwareInterface |
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{ |
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/** |
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* The logger instance. |
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* |
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* @var LoggerInterface |
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*/ |
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protected $logger; |
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/** |
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* Box to pack items into. |
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* |
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* @var Box |
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*/ |
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protected $box; |
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/** |
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* @var int |
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*/ |
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protected $boxWidth; |
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/** |
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* @var int |
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*/ |
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protected $boxLength; |
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/** |
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* List of items to be packed. |
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* |
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* @var ItemList |
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*/ |
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protected $items; |
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/** |
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* List of items temporarily skipped to be packed. |
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* |
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* @var array |
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*/ |
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protected $skippedItems = []; |
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/** |
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* Whether the box was rotated for packing. |
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* |
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* @var bool |
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*/ |
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protected $boxRotated = false; |
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/** |
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* @var PackedLayer[] |
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*/ |
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protected $layers = []; |
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/** |
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* Whether the packer is in look-ahead mode (i.e. working ahead of the main packing). |
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* |
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* @var bool |
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*/ |
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protected $lookAheadMode = false; |
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/** |
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* @var OrientatedItemFactory |
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*/ |
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private $orientatedItemFactory; |
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/** |
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* Constructor. |
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*/ |
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public function __construct(Box $box, ItemList $items) |
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{ |
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$this->box = $box; |
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$this->items = clone $items; |
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$this->boxWidth = max($this->box->getInnerWidth(), $this->box->getInnerLength()); |
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$this->boxLength = min($this->box->getInnerWidth(), $this->box->getInnerLength()); |
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$this->logger = new NullLogger(); |
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// we may have just rotated the box for packing purposes, record if we did |
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if ($this->box->getInnerWidth() !== $this->boxWidth || $this->box->getInnerLength() !== $this->boxLength) { |
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$this->boxRotated = true; |
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} |
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$this->orientatedItemFactory = new OrientatedItemFactory($this->box); |
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$this->orientatedItemFactory->setLogger($this->logger); |
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} |
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/** |
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* Sets a logger. |
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*/ |
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public function setLogger(LoggerInterface $logger): void |
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{ |
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$this->logger = $logger; |
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$this->orientatedItemFactory->setLogger($logger); |
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} |
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/** |
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* @internal |
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*/ |
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public function setLookAheadMode(bool $lookAhead): void |
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{ |
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$this->lookAheadMode = $lookAhead; |
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} |
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/** |
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* Pack as many items as possible into specific given box. |
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* |
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* @return PackedBox packed box |
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*/ |
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public function pack(): PackedBox |
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{ |
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$this->logger->debug("[EVALUATING BOX] {$this->box->getReference()}", ['box' => $this->box]); |
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while ($this->items->count() > 0) { |
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$layerStartDepth = $this->getCurrentPackedDepth(); |
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$this->packLayer($layerStartDepth, $this->boxWidth, $this->boxLength, $this->box->getInnerDepth() - $layerStartDepth); |
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} |
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if ($this->boxRotated) { |
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$this->rotateLayersNinetyDegrees(); |
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} |
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if (!$this->lookAheadMode) { |
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$this->stabiliseLayers(); |
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} |
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$this->logger->debug('done with this box ' . $this->box->getReference()); |
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return new PackedBox($this->box, $this->getPackedItemList()); |
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} |
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/** |
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* Pack items into an individual vertical layer. |
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*/ |
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protected function packLayer(int $startDepth, int $layerWidth, int $lengthLeft, int $depthLeft): void |
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{ |
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$this->layers[] = $layer = new PackedLayer(); |
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$prevItem = null; |
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$x = $y = $rowLength = 0; |
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while ($this->items->count() > 0) { |
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$itemToPack = $this->items->extract(); |
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//skip items that are simply too heavy or too large |
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if (!$this->checkNonDimensionalConstraints($itemToPack)) { |
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continue; |
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} |
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$orientatedItem = $this->getOrientationForItem($itemToPack, $prevItem, $this->items, !$this->hasItemsLeftToPack(), $layerWidth - $x, $lengthLeft, $depthLeft, $rowLength, $x, $y, $startDepth); |
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if ($orientatedItem instanceof OrientatedItem) { |
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$packedItem = PackedItem::fromOrientatedItem($orientatedItem, $x, $y, $startDepth); |
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$layer->insert($packedItem); |
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$rowLength = max($rowLength, $orientatedItem->getLength()); |
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//Figure out if we can stack the next item vertically on top of this rather than side by side |
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//e.g. when we've packed a tall item, and have just put a shorter one next to it. |
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$stackableDepth = $layer->getDepth() - $orientatedItem->getDepth(); |
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$stackedZ = $startDepth + $orientatedItem->getDepth(); |
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while ($this->items->count() > 0 && $this->checkNonDimensionalConstraints($this->items->top())) { |
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$stackedItem = $this->getOrientationForItem($this->items->top(), $prevItem, $this->items, $this->items->count() === 1, $orientatedItem->getWidth(), $orientatedItem->getLength(), $stackableDepth, $rowLength, $x, $y, $stackedZ); |
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if ($stackedItem) { |
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$layer->insert(PackedItem::fromOrientatedItem($stackedItem, $x, $y, $stackedZ)); |
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$this->items->extract(); |
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$stackableDepth -= $stackedItem->getDepth(); |
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$stackedZ += $stackedItem->getDepth(); |
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} else { |
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break; |
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} |
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} |
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$x += $orientatedItem->getWidth(); |
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$prevItem = $packedItem; |
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if ($this->items->count() === 0) { |
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$this->rebuildItemList(); |
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} |
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} elseif (count($layer->getItems()) === 0) { // zero items on layer |
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$this->logger->debug("doesn't fit on layer even when empty, skipping for good"); |
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continue; |
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} elseif ($this->items->count() > 0) { // skip for now, move on to the next item |
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$this->logger->debug("doesn't fit, skipping for now"); |
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$this->skippedItems[] = $itemToPack; |
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// abandon here if next item is the same, no point trying to keep going. Last time is not skipped, need that to trigger appropriate reset logic |
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while ($this->items->count() > 2 && static::isSameDimensions($itemToPack, $this->items->top())) { |
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$this->skippedItems[] = $this->items->extract(); |
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} |
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} elseif ($x > 0) { |
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$this->logger->debug('No more fit in width wise, resetting for new row'); |
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$lengthLeft -= $rowLength; |
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$y += $rowLength; |
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$x = $rowLength = 0; |
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$this->skippedItems[] = $itemToPack; |
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$this->rebuildItemList(); |
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$prevItem = null; |
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continue; |
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} else { |
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$this->logger->debug('no items fit, so starting next vertical layer'); |
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$this->skippedItems[] = $itemToPack; |
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$this->rebuildItemList(); |
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return; |
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} |
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} |
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} |
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/** |
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* During packing, it is quite possible that layers have been created that aren't physically stable |
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* i.e. they overhang the ones below. |
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* |
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* This function reorders them so that the ones with the greatest surface area are placed at the bottom |
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*/ |
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public function stabiliseLayers(): void |
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{ |
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$stabiliser = new LayerStabiliser(); |
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$stabiliser->setLogger($this->logger); |
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$this->layers = $stabiliser->stabilise($this->layers); |
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} |
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protected function getOrientationForItem( |
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Item $itemToPack, |
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?PackedItem $prevItem, |
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ItemList $nextItems, |
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bool $isLastItem, |
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int $maxWidth, |
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int $maxLength, |
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int $maxDepth, |
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int $rowLength, |
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int $x, |
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int $y, |
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int $z |
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): ?OrientatedItem { |
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$this->logger->debug( |
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"evaluating item {$itemToPack->getDescription()} for fit", |
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[ |
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'item' => $itemToPack, |
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'space' => [ |
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'maxWidth' => $maxWidth, |
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'maxLength' => $maxLength, |
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'maxDepth' => $maxDepth, |
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], |
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] |
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); |
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$prevOrientatedItem = $prevItem ? $prevItem->toOrientatedItem() : null; |
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$prevPackedItemList = $itemToPack instanceof ConstrainedPlacementItem ? $this->getPackedItemList() : new PackedItemList(); // don't calculate it if not going to be used |
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return $this->orientatedItemFactory->getBestOrientation($itemToPack, $prevOrientatedItem, $nextItems, $isLastItem, $maxWidth, $maxLength, $maxDepth, $rowLength, $x, $y, $z, $prevPackedItemList); |
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} |
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/** |
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* As well as purely dimensional constraints, there are other constraints that need to be met |
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* e.g. weight limits or item-specific restrictions (e.g. max <x> batteries per box). |
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*/ |
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protected function checkNonDimensionalConstraints(Item $itemToPack): bool |
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{ |
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$customConstraintsOK = true; |
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if ($itemToPack instanceof ConstrainedItem) { |
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$customConstraintsOK = $itemToPack->canBePackedInBox($this->getPackedItemList(), $this->box); |
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} |
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return $customConstraintsOK && $itemToPack->getWeight() <= $this->getRemainingWeightAllowed(); |
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} |
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/** |
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* Reintegrate skipped items into main list. |
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*/ |
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protected function rebuildItemList(): void |
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{ |
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$this->items = ItemList::fromArray(array_merge($this->skippedItems, iterator_to_array($this->items)), true); |
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$this->skippedItems = []; |
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} |
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/** |
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* Swap back width/length of the packed items to match orientation of the box if needed. |
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*/ |
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protected function rotateLayersNinetyDegrees(): void |
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{ |
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foreach ($this->layers as $i => $originalLayer) { |
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$newLayer = new PackedLayer(); |
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foreach ($originalLayer->getItems() as $item) { |
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$packedItem = new PackedItem($item->getItem(), $item->getY(), $item->getX(), $item->getZ(), $item->getLength(), $item->getWidth(), $item->getDepth()); |
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$newLayer->insert($packedItem); |
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} |
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$this->layers[$i] = $newLayer; |
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} |
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} |
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/** |
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* Are there items left to pack? |
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*/ |
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protected function hasItemsLeftToPack(): bool |
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{ |
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return count($this->skippedItems) + $this->items->count() > 0; |
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} |
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/** |
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* Generate a single list of items packed. |
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*/ |
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protected function getPackedItemList(): PackedItemList |
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{ |
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$packedItemList = new PackedItemList(); |
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foreach ($this->layers as $layer) { |
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foreach ($layer->getItems() as $packedItem) { |
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$packedItemList->insert($packedItem); |
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} |
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} |
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return $packedItemList; |
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} |
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/** |
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* Return the current packed depth. |
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*/ |
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protected function getCurrentPackedDepth(): int |
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{ |
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$depth = 0; |
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foreach ($this->layers as $layer) { |
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$depth += $layer->getDepth(); |
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} |
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return $depth; |
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} |
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private function getRemainingWeightAllowed(): int |
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{ |
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$remainingWeightAllowed = $this->box->getMaxWeight() - $this->box->getEmptyWeight(); |
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foreach ($this->layers as $layer) { |
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$remainingWeightAllowed -= $layer->getWeight(); |
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} |
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return $remainingWeightAllowed; |
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} |
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/** |
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* Compare two items to see if they have same dimensions. |
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*/ |
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protected static function isSameDimensions(Item $itemA, Item $itemB): bool |
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{ |
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if ($itemA === $itemB) { |
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return true; |
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|
|
|
} |
363
|
7 |
|
$itemADimensions = [$itemA->getWidth(), $itemA->getLength(), $itemA->getDepth()]; |
364
|
7 |
|
$itemBDimensions = [$itemB->getWidth(), $itemB->getLength(), $itemB->getDepth()]; |
365
|
7 |
|
sort($itemADimensions); |
366
|
7 |
|
sort($itemBDimensions); |
367
|
|
|
|
368
|
7 |
|
return $itemADimensions === $itemBDimensions; |
369
|
|
|
} |
370
|
|
|
} |
371
|
|
|
|