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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 InvalidArgumentException; |
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use Seboettg\Collection\ArrayList; |
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use Seboettg\Collection\ArrayList\ArrayListInterface; |
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use Seboettg\Forest\BinaryTree\BinaryNodeInterface; |
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use Seboettg\Forest\General\TreeNodeInterface; |
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/** |
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* Class InOrderVisitor |
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* Implements the tree traversal strategy In-order. |
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* In this traversal strategy, the left subtree is visited first, then the root and later the right sub-tree. |
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* If a binary tree is traversed in-order, the output will produce sorted key values in an ascending order. |
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* |
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* @package Seboettg\Forest\Visitor |
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*/ |
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class InOrderVisitor implements VisitorInterface |
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{ |
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public function visit(TreeNodeInterface $node): ArrayListInterface |
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{ |
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if (!$node instanceof BinaryNodeInterface) { |
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throw new InvalidArgumentException(BinaryNodeInterface::class . " expected, got " . get_class($node) . "."); |
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} |
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$resultList = new ArrayList(); |
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if ($node !== null) { |
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$left = $node->getLeft(); |
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$right = $node->getRight(); |
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if ($left !== null) { |
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$resultList->merge($left->accept($this)); |
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} |
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$resultList->append($node->getItem()); |
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if ($right !== null) { |
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$resultList->merge($right->accept($this)); |
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} |
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} |
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return $resultList; |
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} |
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} |
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seboettg /
Forest
