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run code in 200+ php & hhvm versions
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<?php class CategoryTree { protected $roots = []; public function addCategory($category, $parent) { if ($this->categoryExists($this->roots, $category)) { throw new InvalidArgumentException(); } if ($parent === null) { $this->tree[$category] = []; return; } $node = $findNode($parent, $this->root); if(!isset($node)) { throw new InvalidArgumentException(); } $node[$category] = []; } public function getChildren($parent) { $node = $findNode($parent, $this->root); if(!isset($node)) { throw new InvalidArgumentException(); } return array_keys($node); } public function findNode($node, &$root) { if (in_array($node, array_keys($root))) { return $root[$node]; } foreach ($root as $n) { return $this->findNode($node, $n); } } public function categoryExists($nodes, $category) { $exists = false; foreach($nodes as $node) { if (in_array($category, $this->getChildren($node))) { return true; } $exists = $this->categoryExists($node, $category); } return $exists; } } // For testing purposes (do not submit uncommented): $c = new CategoryTree; $c->addCategory('A', null); $c->addCategory('B', 'A'); $c->addCategory('C', 'A'); //echo implode(',', $c->getChildren('A'));
based on kQpk6
Output for 7.0.0 - 7.2.0
Notice: Undefined variable: findNode in /in/A95Ug on line 18 Fatal error: Uncaught Error: Function name must be a string in /in/A95Ug:18 Stack trace: #0 /in/A95Ug(58): CategoryTree->addCategory('B', 'A') #1 {main} thrown in /in/A95Ug on line 18
Process exited with code 255.
Output for 5.4.10 - 5.6.28
Notice: Undefined variable: findNode in /in/A95Ug on line 18 Fatal error: Function name must be a string in /in/A95Ug on line 18
Process exited with code 255.
Output for 5.3.20 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/A95Ug on line 4
Process exited with code 255.