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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 array_map; |
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use ArrayIterator; |
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use function count; |
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use Countable; |
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use IteratorAggregate; |
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use Traversable; |
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use function usort; |
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/** |
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* List of packed items, ordered by volume. |
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* |
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* @author Doug Wright |
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*/ |
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class PackedItemList implements Countable, IteratorAggregate |
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{ |
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/** |
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* List containing items. |
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* |
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* @var PackedItem[] |
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*/ |
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private $list = []; |
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private $weight = 0; |
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/** |
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* Has this list already been sorted? |
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* |
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* @var bool |
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*/ |
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private $isSorted = false; |
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public function insert(PackedItem $item): void |
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{ |
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$this->list[] = $item; |
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$this->weight += $item->getItem()->getWeight(); |
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} |
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/** |
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* @return Traversable|PackedItem[] |
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*/ |
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public function getIterator(): Traversable |
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{ |
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if (!$this->isSorted) { |
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usort($this->list, [$this, 'compare']); |
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$this->isSorted = true; |
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} |
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return new ArrayIterator($this->list); |
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} |
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/** |
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* Number of items in list. |
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*/ |
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public function count(): int |
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{ |
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return count($this->list); |
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} |
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/** |
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* Get copy of this list as a standard PHP array. |
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* |
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* @internal |
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* |
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* @return Item[] |
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*/ |
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public function asItemArray(): array |
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{ |
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return array_map(function (PackedItem $packedItem) { |
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return $packedItem->getItem(); |
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}, $this->list); |
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} |
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/** |
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* Get total volume of these items. |
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*/ |
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public function getVolume(): int |
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{ |
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$volume = 0; |
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foreach ($this->list as $item) { |
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$volume += $item->getVolume(); |
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} |
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return $volume; |
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} |
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/** |
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* Get total weight of these items. |
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*/ |
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public function getWeight(): int |
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{ |
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return $this->weight; |
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} |
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private function compare(PackedItem $itemA, PackedItem $itemB): int |
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{ |
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$itemAVolume = $itemA->getItem()->getWidth() * $itemA->getItem()->getLength() * $itemA->getItem()->getDepth(); |
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$itemBVolume = $itemB->getItem()->getWidth() * $itemB->getItem()->getLength() * $itemB->getItem()->getDepth(); |
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return ($itemBVolume <=> $itemAVolume) ?: ($itemB->getItem()->getWeight() <=> $itemA->getItem()->getWeight()); |
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} |
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} |
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