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<?php |
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declare(strict_types=1); |
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/* |
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* Copyright (C) 2019 Sebastian Böttger <[email protected]> |
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* You may use, distribute and modify this code under the |
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* terms of the MIT license. |
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* |
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* You should have received a copy of the MIT license with |
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* this file. If not, please visit: https://opensource.org/licenses/mit-license.php |
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*/ |
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namespace Seboettg\Forest\Visitor; |
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use Seboettg\Collection\ArrayList; |
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use Seboettg\Collection\ArrayList\ArrayListInterface; |
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use Seboettg\Collection\Queue; |
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use Seboettg\Forest\General\TreeNodeInterface; |
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/** |
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* Class LevelOrderVisitor |
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* Implements the tree traversal strategy Level-order. |
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* In this traversal strategy, the root node is visited first, than all nodes of the next level and so on. |
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* |
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* @package Seboettg\Forest\Visitor |
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*/ |
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class LevelOrderVisitor implements VisitorInterface |
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{ |
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public function visit(TreeNodeInterface $node): ArrayListInterface |
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{ |
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$result = new ArrayList(); |
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$queue = new Queue(); |
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$queue->enqueue($node); |
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return $this->traverseLevelOrder($result, $queue); |
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} |
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/** |
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* @param ArrayListInterface $target |
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* @param Queue $queue |
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* @return ArrayListInterface |
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*/ |
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private function traverseLevelOrder(ArrayListInterface $target, Queue $queue): ArrayListInterface |
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{ |
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while ($queue->count() > 0) { |
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/** @var TreeNodeInterface $node */ |
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$node = $queue->dequeue(); |
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//enqueue all children to the queue for traversing the next level |
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foreach ($node->getChildren() as $child) { |
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$queue->enqueue($child); |
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} |
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$target->append($node->getItem()); |
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} |
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return $target; |
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} |
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} |
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seboettg /
Forest
