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<?php |
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namespace Letournel\PathFinder\Algorithms\ShortestDistance; |
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use Letournel\PathFinder\AlgorithmShortestDistance; |
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use Letournel\PathFinder\Core\Node; |
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use Letournel\PathFinder\Core\NodeGraph; |
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use Letournel\PathFinder\Core\NodeGrid; |
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use Letournel\PathFinder\Core\NodePriorityQueueMin; |
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use Letournel\PathFinder\Distance; |
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class Dijkstra implements AlgorithmShortestDistance |
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{ |
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/* |
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* For more info see |
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* http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm |
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*/ |
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private |
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$distance, |
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$distanceGraph, |
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$grid; |
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public function __construct(Distance $distance) |
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{ |
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$this->distance = $distance; |
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} |
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public function setGrid(NodeGrid $grid) |
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{ |
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$this->grid = $grid; |
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$this->distanceGraph = new NodeGraph($grid->buildWalkableNodesList()); |
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$this->distanceGraph->setSymetricMode(false); |
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} |
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View Code Duplication |
public function computeLength(Node $source, Node $target) |
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{ |
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if(! $this->grid instanceof NodeGrid) |
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{ |
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throw new \RuntimeException('Invalid Grid'); |
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} |
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if(! $this->distanceGraph instanceof NodeGraph) |
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{ |
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throw new \RuntimeException('Invalid Graph'); |
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} |
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$edges = $this->distanceGraph->getEdgesFrom($source); |
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if(empty($edges)) |
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{ |
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$this->computeDistanceGraph(array($source)); |
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} |
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return $this->distanceGraph->getEdgeBetween($source, $target); |
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} |
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private function computeDistanceGraph(array $nodesList) |
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{ |
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foreach($nodesList as $source) |
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{ |
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$priorityQueue = new NodePriorityQueueMin(); |
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$priorityQueue->insert($source, 0); |
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while(! $priorityQueue->isEmpty()) |
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{ |
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$node = $priorityQueue->extract(); |
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$neighbors = $this->grid->getWalkableNeighbors($node); |
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foreach($neighbors as $neighbor) |
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{ |
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$alternativeDistance = $this->distanceGraph->getEdgeBetween($source, $node) + $this->distance->compute($node, $neighbor); |
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if(! $this->distanceGraph->existsEdgeBetween($source, $neighbor) || $alternativeDistance < $this->distanceGraph->getEdgeBetween($source, $neighbor)) |
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{ |
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$priorityQueue->insert($neighbor, $alternativeDistance); |
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$this->distanceGraph->createEdgeBetween($source, $neighbor, $alternativeDistance); |
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} |
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} |
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} |
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} |
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} |
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} |
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letournel /
path-finder
Loading history...
Only declaring a single property per statement allows you to later on add doc comments more easily.
It is also recommended by PSR2, so it is a common style that many people expect.