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<?php |
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/** |
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* Box packing (3D bin packing, knapsack problem) |
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* @package BoxPacker |
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* @author Doug Wright |
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*/ |
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namespace DVDoug\BoxPacker; |
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use Psr\Log\LoggerAwareInterface; |
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use Psr\Log\LoggerAwareTrait; |
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use Psr\Log\NullLogger; |
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/** |
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* Actual packer |
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* @author Doug Wright |
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* @package BoxPacker |
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*/ |
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class VolumePacker implements LoggerAwareInterface |
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{ |
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use LoggerAwareTrait; |
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/** |
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* Box to pack items into |
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* @var Box |
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*/ |
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protected $box; |
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/** |
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* List of items to be packed |
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* @var ItemList |
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*/ |
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protected $items; |
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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 = $items; |
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$this->logger = new NullLogger(); |
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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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* @return PackedBox packed box |
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*/ |
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public function pack() |
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{ |
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$this->logger->debug("[EVALUATING BOX] {$this->box->getReference()}"); |
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$packedItems = new ItemList; |
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$depthLeft = $this->box->getInnerDepth(); |
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$remainingWeight = $this->box->getMaxWeight() - $this->box->getEmptyWeight(); |
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$widthLeft = $this->box->getInnerWidth(); |
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$lengthLeft = $this->box->getInnerLength(); |
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$layerWidth = $layerLength = $layerDepth = 0; |
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$prevItem = null; |
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while (!$this->items->isEmpty()) { |
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$itemToPack = $this->items->extract(); |
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//skip items that are simply too heavy |
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if ($itemToPack->getWeight() > $remainingWeight) { |
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continue; |
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} |
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$this->logger->debug("evaluating item {$itemToPack->getDescription()}"); |
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$this->logger->debug("remaining width: {$widthLeft}, length: {$lengthLeft}, depth: {$depthLeft}"); |
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$this->logger->debug("layerWidth: {$layerWidth}, layerLength: {$layerLength}, layerDepth: {$layerDepth}"); |
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$nextItem = !$this->items->isEmpty() ? $this->items->top() : null; |
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$orientatedItem = $this->findBestOrientation($itemToPack, $prevItem, $nextItem, $widthLeft, $lengthLeft, $depthLeft); |
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if ($orientatedItem) { |
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$packedItems->insert($orientatedItem->getItem()); |
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$remainingWeight -= $itemToPack->getWeight(); |
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$lengthLeft -= $orientatedItem->getLength(); |
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$layerLength += $orientatedItem->getLength(); |
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$layerWidth = max($orientatedItem->getWidth(), $layerWidth); |
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$layerDepth = max($layerDepth, $orientatedItem->getDepth()); //greater than 0, items will always be less deep |
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//allow items to be stacked in place within the same footprint up to current layerdepth |
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$maxStackDepth = $layerDepth - $orientatedItem->getDepth(); |
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while (!$this->items->isEmpty() && $this->canStackItemInLayer($itemToPack, $this->items->top(), $maxStackDepth, $remainingWeight)) { |
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$remainingWeight -= $this->items->top()->getWeight(); |
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$maxStackDepth -= $this->items->top()->getDepth(); // XXX no attempt at best fit |
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$packedItems->insert($this->items->extract()); |
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} |
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$prevItem = $orientatedItem; |
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} else { |
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$prevItem = null; |
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if ($widthLeft >= min($itemToPack->getWidth(), $itemToPack->getLength()) && $this->isLayerStarted($layerWidth, $layerLength, $layerDepth)) { |
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$this->logger->debug("No more fit in lengthwise, resetting for new row"); |
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$lengthLeft += $layerLength; |
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$widthLeft -= $layerWidth; |
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$layerWidth = $layerLength = 0; |
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$this->items->insert($itemToPack); |
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continue; |
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} elseif ($lengthLeft < min($itemToPack->getWidth(), $itemToPack->getLength()) || $layerDepth == 0) { |
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$this->logger->debug("doesn't fit on layer even when empty"); |
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continue; |
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} |
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$widthLeft = $layerWidth ? min(floor($layerWidth * 1.1), $this->box->getInnerWidth()) : $this->box->getInnerWidth(); |
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$lengthLeft = $layerLength ? min(floor($layerLength * 1.1), $this->box->getInnerLength()) : $this->box->getInnerLength(); |
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$depthLeft -= $layerDepth; |
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$layerWidth = $layerLength = $layerDepth = 0; |
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$this->logger->debug("doesn't fit, so starting next vertical layer"); |
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$this->items->insert($itemToPack); |
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} |
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} |
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$this->logger->debug("done with this box"); |
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return new PackedBox($this->box, $packedItems, $widthLeft, $lengthLeft, $depthLeft, $remainingWeight); |
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} |
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/** |
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* Get the best orientation for an item |
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* @param Item $item |
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* @param OrientatedItem|null $prevItem |
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* @param Item|null $nextItem |
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* @param int $widthLeft |
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* @param int $lengthLeft |
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* @param int $depthLeft |
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* @return OrientatedItem|false |
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*/ |
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protected function findBestOrientation(Item $item, OrientatedItem $prevItem = null, Item $nextItem = null, $widthLeft, $lengthLeft, $depthLeft) { |
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$orientations = $this->findPossibleOrientations($item, $prevItem, $widthLeft, $lengthLeft, $depthLeft); |
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if (empty($orientations)) { |
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return false; |
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} |
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// special casing based on next item |
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if (isset($orientations[0]) && $nextItem == $item && $lengthLeft >= 2 * $item->getLength()) { |
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$this->logger->debug("not rotating based on next item"); |
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return $orientations[0]; // XXX this is tied to the ordering from ->findPossibleOrientations() |
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} |
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$orientationFits = []; |
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/** @var OrientatedItem $orientation */ |
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foreach ($orientations as $o => $orientation) { |
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$orientationFit = min($widthLeft - $orientation->getWidth(), $lengthLeft - $orientation->getLength()); |
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$orientationFits[$o] = $orientationFit; |
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} |
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if ($orientationFits) { |
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asort($orientationFits); |
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reset($orientationFits); |
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$bestFit = key($orientationFits); |
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$this->logger->debug("Using orientation #{$bestFit}"); |
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return $orientations[$bestFit]; |
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} else { |
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return false; |
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} |
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} |
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/** |
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* Find all possible orientations for an item |
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* @param Item $item |
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* @param OrientatedItem|null $prevItem |
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* @param int $widthLeft |
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* @param int $lengthLeft |
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* @param int $depthLeft |
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* @return OrientatedItem[] |
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*/ |
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protected function findPossibleOrientations(Item $item, OrientatedItem $prevItem = null, $widthLeft, $lengthLeft, $depthLeft) { |
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$orientations = []; |
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//Special case items that are the same as what we just packed - keep orientation |
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if ($prevItem && $prevItem->getItem() == $item) { |
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$orientations[] = new OrientatedItem($item, $prevItem->getWidth(), $prevItem->getLength(), $prevItem->getDepth()); |
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} else { |
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//simple 2D rotation |
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$orientations[] = new OrientatedItem($item, $item->getWidth(), $item->getLength(), $item->getDepth()); |
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$orientations[] = new OrientatedItem($item, $item->getLength(), $item->getWidth(), $item->getDepth()); |
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//add 3D rotation if we're allowed |
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if (!$item->getKeepFlat()) { |
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$orientations[] = new OrientatedItem($item, $item->getWidth(), $item->getDepth(), $item->getLength()); |
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$orientations[] = new OrientatedItem($item, $item->getLength(), $item->getDepth(), $item->getWidth()); |
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$orientations[] = new OrientatedItem($item, $item->getDepth(), $item->getWidth(), $item->getLength()); |
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$orientations[] = new OrientatedItem($item, $item->getDepth(), $item->getLength(), $item->getWidth()); |
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} |
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} |
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//remove any that simply don't fit |
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return array_filter($orientations, function (OrientatedItem $i) use ($widthLeft, $lengthLeft, $depthLeft) { |
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return $i->getWidth() <= $widthLeft && $i->getLength() <= $lengthLeft && $i->getDepth() <= $depthLeft; |
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}); |
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} |
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/** |
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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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* Used when we've packed a tall item, and have just put a shorter one next to it |
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* @param Item $item |
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* @param Item $nextItem |
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* @param $maxStackDepth |
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* @param $remainingWeight |
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* @return bool |
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*/ |
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protected function canStackItemInLayer(Item $item, Item $nextItem, $maxStackDepth, $remainingWeight) |
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{ |
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return $nextItem->getDepth() <= $maxStackDepth && |
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$nextItem->getWeight() <= $remainingWeight && |
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$nextItem->getWidth() <= $item->getWidth() && |
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$nextItem->getLength() <= $item->getLength(); |
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} |
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/** |
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* @param int $layerWidth |
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* @param int $layerLength |
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* @param int $layerDepth |
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* @return bool |
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*/ |
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protected function isLayerStarted($layerWidth, $layerLength, $layerDepth) { |
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return $layerWidth > 0 && $layerLength > 0 && $layerDepth > 0; |
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} |
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} |
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This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.