Passed
Push — 2.x-dev ( 794087...7794d8 )
by Doug
01:28
created

VolumePacker::pack()   A

Complexity

Conditions 3
Paths 4

Size

Total Lines 18
Code Lines 9

Duplication

Lines 0
Ratio 0 %

Code Coverage

Tests 10
CRAP Score 3

Importance

Changes 0
Metric Value
cc 3
eloc 9
nc 4
nop 0
dl 0
loc 18
ccs 10
cts 10
cp 1
crap 3
rs 9.9666
c 0
b 0
f 0
1
<?php
2
/**
3
 * Box packing (3D bin packing, knapsack problem).
4
 *
5
 * @author Doug Wright
6
 */
7
8
namespace DVDoug\BoxPacker;
9
10
use Psr\Log\LoggerAwareInterface;
11
use Psr\Log\LoggerAwareTrait;
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use Psr\Log\NullLogger;
13
14
/**
15
 * Actual packer.
16
 *
17
 * @author Doug Wright
18
 */
19
class VolumePacker implements LoggerAwareInterface
20
{
21
    use LoggerAwareTrait;
22
23
    /**
24
     * Box to pack items into.
25
     *
26
     * @var Box
27
     */
28
    protected $box;
29
30
    /**
31
     * @var int
32
     */
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    protected $boxWidth;
34
35
    /**
36
     * @var int
37
     */
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    protected $boxLength;
39
40
    /**
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     * List of items to be packed.
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     *
43
     * @var ItemList
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     */
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    protected $items;
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47
    /**
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     * List of items temporarily skipped to be packed.
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     *
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     * @var ItemList
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     */
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    protected $skippedItems;
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54
    /**
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     * Remaining weight capacity of the box.
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     *
57
     * @var int
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     */
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    protected $remainingWeight;
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61
    /**
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     * Whether the box was rotated for packing.
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     *
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     * @var bool
65
     */
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    protected $boxRotated = false;
67
68
    /**
69
     * @var PackedLayer[]
70
     */
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    protected $layers = [];
72
73
    /**
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     * Constructor.
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     *
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     * @param Box      $box
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     * @param ItemList $items
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     */
79 30
    public function __construct(Box $box, ItemList $items)
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    {
81 30
        $this->box = $box;
82 30
        $this->items = $items;
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84 30
        $this->boxWidth = max($this->box->getInnerWidth(), $this->box->getInnerLength());
85 30
        $this->boxLength = min($this->box->getInnerWidth(), $this->box->getInnerLength());
86 30
        $this->remainingWeight = $this->box->getMaxWeight() - $this->box->getEmptyWeight();
87 30
        $this->skippedItems = new ItemList();
88 30
        $this->logger = new NullLogger();
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90
        // we may have just rotated the box for packing purposes, record if we did
91 30
        if ($this->box->getInnerWidth() !== $this->boxWidth || $this->box->getInnerLength() !== $this->boxLength) {
92 9
            $this->boxRotated = true;
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        }
94 30
    }
95
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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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     */
101 30
    public function pack()
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    {
103 30
        $this->logger->debug("[EVALUATING BOX] {$this->box->getReference()}");
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105 30
        while (count($this->items) > 0) {
106 30
            $layerStartDepth = $this->getCurrentPackedDepth();
107 30
            $this->packLayer($layerStartDepth, $this->boxWidth, $this->boxLength, $this->box->getInnerDepth() - $layerStartDepth);
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        }
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110 30
        if ($this->boxRotated) {
111 9
            $this->rotateLayersNinetyDegrees();
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        }
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114 30
        $this->stabiliseLayers();
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116 30
        $this->logger->debug('done with this box');
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118 30
        return PackedBox::fromPackedItemList($this->box, $this->getPackedItemList());
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    }
120
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    /**
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     * Pack items into an individual vertical layer.
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     *
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     * @param int $startDepth
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     * @param int $widthLeft
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     * @param int $lengthLeft
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     * @param int $depthLeft
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     */
129 30
    protected function packLayer($startDepth, $widthLeft, $lengthLeft, $depthLeft)
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    {
131 30
        $this->layers[] = $layer = new PackedLayer();
132 30
        $prevItem = null;
133 30
        $x = $y = $rowWidth = $rowLength = $layerDepth = 0;
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135 30
        while (count($this->items) > 0) {
136 30
            $itemToPack = $this->items->extract();
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            //skip items that are simply too heavy or too large
139 30
            if (!$this->checkConstraints($itemToPack)) {
140 6
                $this->rebuildItemList();
141 6
                continue;
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            }
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144 30
            $orientatedItem = $this->getOrientationForItem($itemToPack, $prevItem, $this->items, $this->hasItemsLeftToPack(), $widthLeft, $lengthLeft, $depthLeft);
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146 30
            if ($orientatedItem instanceof OrientatedItem) {
147 30
                $packedItem = PackedItem::fromOrientatedItem($orientatedItem, $x, $y, $startDepth);
148 30
                $layer->insert($packedItem);
149 30
                $this->remainingWeight -= $orientatedItem->getItem()->getWeight();
150 30
                $widthLeft -= $orientatedItem->getWidth();
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152 30
                $rowWidth += $orientatedItem->getWidth();
153 30
                $rowLength = max($rowLength, $orientatedItem->getLength());
154 30
                $layerDepth = max($layerDepth, $orientatedItem->getDepth());
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                //allow items to be stacked in place within the same footprint up to current layer depth
157 30
                $stackableDepth = $layerDepth - $orientatedItem->getDepth();
158 30
                $this->tryAndStackItemsIntoSpace($layer, $prevItem, $this->items, $orientatedItem->getWidth(), $orientatedItem->getLength(), $stackableDepth, $x, $y, $startDepth + $orientatedItem->getDepth());
159 30
                $x += $orientatedItem->getWidth();
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161 30
                $prevItem = $packedItem;
162 30
                $this->rebuildItemList();
163 21
            } elseif (count($layer->getItems()) === 0) { // zero items on layer
164 1
                $this->logger->debug("doesn't fit on layer even when empty, skipping for good");
165 1
                continue;
166 21
            } elseif ($widthLeft > 0 && count($this->items) > 0) { // skip for now, move on to the next item
167 16
                $this->logger->debug("doesn't fit, skipping for now");
168 16
                $this->skippedItems->insert($itemToPack);
169 21
            } elseif ($x > 0 && $lengthLeft >= min($itemToPack->getWidth(), $itemToPack->getLength(), $itemToPack->getDepth())) {
170 21
                $this->logger->debug('No more fit in width wise, resetting for new row');
171 21
                $widthLeft += $rowWidth;
172 21
                $lengthLeft -= $rowLength;
173 21
                $y += $rowLength;
174 21
                $x = $rowWidth = $rowLength = 0;
175 21
                $this->rebuildItemList($itemToPack);
176 21
                $prevItem = null;
177 21
                continue;
178
            } else {
179 13
                $this->logger->debug('no items fit, so starting next vertical layer');
180 13
                $this->rebuildItemList($itemToPack);
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182 13
                return;
183
            }
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        }
185 30
    }
186
187
    /**
188
     * During packing, it is quite possible that layers have been created that aren't physically stable
189
     * i.e. they overhang the ones below.
190
     *
191
     * This function reorders them so that the ones with the greatest surface area are placed at the bottom
192
     */
193 30
    public function stabiliseLayers()
194
    {
195 30
        $stabiliser = new LayerStabiliser();
196 30
        $this->layers = $stabiliser->stabilise($this->layers);
197 30
    }
198
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    /**
200
     * @param Item            $itemToPack
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     * @param PackedItem|null $prevItem
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     * @param ItemList        $nextItems
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     * @param bool            $isLastItem
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     * @param int             $maxWidth
205
     * @param int             $maxLength
206
     * @param int             $maxDepth
207
     *
208
     * @return OrientatedItem|null
209
     */
210 30
    protected function getOrientationForItem(
211
        Item $itemToPack,
212
        PackedItem $prevItem = null,
213
        ItemList $nextItems,
214
        $isLastItem,
215
        $maxWidth,
216
        $maxLength,
217
        $maxDepth
218
    ) {
219 30
        $this->logger->debug(
220 30
            "evaluating item {$itemToPack->getDescription()} for fit",
221
            [
222 30
                'item' => $itemToPack,
223
                'space' => [
224 30
                    'maxWidth' => $maxWidth,
225 30
                    'maxLength' => $maxLength,
226 30
                    'maxDepth' => $maxDepth,
227
                ],
228
            ]
229
        );
230
231 30
        $prevOrientatedItem = $prevItem ? $prevItem->toOrientatedItem() : null;
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233 30
        $orientatedItemFactory = new OrientatedItemFactory($this->box);
234 30
        $orientatedItemFactory->setLogger($this->logger);
235 30
        $orientatedItemDecision = $orientatedItemFactory->getBestOrientation($itemToPack, $prevOrientatedItem, $nextItems, $isLastItem, $maxWidth, $maxLength, $maxDepth);
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237 30
        return $orientatedItemDecision;
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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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     *
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     * @param PackedLayer     $layer
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     * @param PackedItem|null $prevItem
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     * @param ItemList        $nextItems
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     * @param int             $maxWidth
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     * @param int             $maxLength
249
     * @param int             $maxDepth
250
     * @param int             $x
251
     * @param int             $y
252
     * @param int             $z
253
     */
254 30
    protected function tryAndStackItemsIntoSpace(
255
        PackedLayer $layer,
256
        PackedItem $prevItem = null,
257
        ItemList $nextItems,
258
        $maxWidth,
259
        $maxLength,
260
        $maxDepth,
261
        $x,
262
        $y,
263
        $z
264
    ) {
265 30
        while (count($this->items) > 0 && $this->checkNonDimensionalConstraints($this->items->top())) {
266 29
            $stackedItem = $this->getOrientationForItem(
267 29
                $this->items->top(),
268 29
                $prevItem,
269 29
                $nextItems,
270 29
                $this->items->count() === 1,
271 29
                $maxWidth,
272 29
                $maxLength,
273 29
                $maxDepth
274
            );
275 29
            if ($stackedItem) {
276 2
                $this->remainingWeight -= $this->items->top()->getWeight();
277 2
                $layer->insert(PackedItem::fromOrientatedItem($stackedItem, $x, $y, $z));
278 2
                $this->items->extract();
279 2
                $maxDepth -= $stackedItem->getDepth();
280 2
                $z += $stackedItem->getDepth();
281
            } else {
282 29
                break;
283
            }
284
        }
285 30
    }
286
287
    /**
288
     * Check item generally fits into box.
289
     *
290
     * @param Item $itemToPack
291
     *
292
     * @return bool
293
     */
294 30
    protected function checkConstraints(
295
        Item $itemToPack
296
    ) {
297 30
        return $this->checkNonDimensionalConstraints($itemToPack) &&
298 30
               $this->checkDimensionalConstraints($itemToPack);
299
    }
300
301
    /**
302
     * As well as purely dimensional constraints, there are other constraints that need to be met
303
     * e.g. weight limits or item-specific restrictions (e.g. max <x> batteries per box).
304
     *
305
     * @param Item $itemToPack
306
     *
307
     * @return bool
308
     */
309 30
    protected function checkNonDimensionalConstraints(Item $itemToPack)
310
    {
311 30
        $weightOK = $itemToPack->getWeight() <= $this->remainingWeight;
312
313 30
        if ($itemToPack instanceof ConstrainedItem) {
314 1
            return $weightOK && $itemToPack->canBePackedInBox($this->getPackedItemList()->asItemList(), $this->box);
315
        }
316
317 30
        return $weightOK;
318
    }
319
320
    /**
321
     * Check the item physically fits in the box (at all).
322
     *
323
     * @param Item $itemToPack
324
     *
325
     * @return bool
326
     */
327 30
    protected function checkDimensionalConstraints(Item $itemToPack)
328
    {
329 30
        $orientatedItemFactory = new OrientatedItemFactory($this->box);
330 30
        $orientatedItemFactory->setLogger($this->logger);
331
332 30
        return (bool) $orientatedItemFactory->getPossibleOrientationsInEmptyBox($itemToPack);
333
    }
334
335
    /**
336
     * Reintegrate skipped items into main list.
337
     *
338
     * @param Item|null $currentItem item from current iteration
339
     */
340 30
    protected function rebuildItemList(Item $currentItem = null)
341
    {
342 30
        if (count($this->items) === 0) {
343 30
            $this->items = $this->skippedItems;
344 30
            $this->skippedItems = new ItemList();
345
        }
346
347 30
        if ($currentItem instanceof Item) {
348 21
            $this->items->insert($currentItem);
349
        }
350 30
    }
351
352
    /**
353
     * Swap back width/length of the packed items to match orientation of the box if needed.
354
     */
355 9
    protected function rotateLayersNinetyDegrees()
356
    {
357 9
        foreach ($this->layers as $i => $originalLayer) {
358 9
            $newLayer = new PackedLayer();
359 9
            foreach ($originalLayer->getItems() as $item) {
360 9
                $packedItem = new PackedItem($item->getItem(), $item->getY(), $item->getX(), $item->getZ(), $item->getLength(), $item->getWidth(), $item->getDepth());
361 9
                $newLayer->insert($packedItem);
362
            }
363 9
            $this->layers[$i] = $newLayer;
364
        }
365 9
    }
366
367
    /**
368
     * Are there items left to pack?
369
     *
370
     * @return bool
371
     */
372 30
    protected function hasItemsLeftToPack()
373
    {
374 30
        return count($this->skippedItems) + count($this->items) === 0;
375
    }
376
377
    /**
378
     * Generate a single list of items packed.
379
     *
380
     * @return PackedItemList
381
     */
382 30
    protected function getPackedItemList()
383
    {
384 30
        $packedItemList = new PackedItemList();
385 30
        foreach ($this->layers as $layer) {
386 30
            foreach ($layer->getItems() as $packedItem) {
387 30
                $packedItemList->insert($packedItem);
388
            }
389
        }
390
391 30
        return $packedItemList;
392
    }
393
394
    /**
395
     * Return the current packed depth.
396
     *
397
     * @return int
398
     */
399 30
    protected function getCurrentPackedDepth()
400
    {
401 30
        $depth = 0;
402 30
        foreach ($this->layers as $layer) {
403 13
            $depth += $layer->getDepth();
404
        }
405
406 30
        return $depth;
407
    }
408
}
409