Complex classes like Tree often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Tree, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 14 | class Tree |
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| 15 | { |
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| 16 | /** |
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| 17 | * Set the build mode simple and add a depth field for branches |
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| 18 | * @const int |
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| 19 | */ |
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| 20 | const BUILD_MODE_DEPTH = 0; |
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| 21 | |||
| 22 | /** |
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| 23 | * Builds simple mode and add left->right fields |
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| 24 | * @const int |
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| 25 | */ |
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| 26 | const BUILD_MODE_LEFT_RIGHT = 1; |
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| 27 | |||
| 28 | /** |
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| 29 | * Builds the full type off tree, containing all off the above |
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| 30 | * @const int |
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| 31 | */ |
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| 32 | const BUILD_MODE_COMPLETE = 2; |
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| 33 | |||
| 34 | /** |
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| 35 | * Default parent id from where to start referencing |
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| 36 | * @const int |
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| 37 | */ |
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| 38 | const ROOT_PARENT_ID = 0; |
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| 39 | |||
| 40 | /** |
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| 41 | * Wheather to log debug details |
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| 42 | * @var boolean |
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| 43 | */ |
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| 44 | private $debug = false; |
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| 45 | |||
| 46 | /** |
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| 47 | * Collected debug data if enabled |
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| 48 | * @var string |
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| 49 | */ |
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| 50 | private $debugData; |
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| 51 | |||
| 52 | /** |
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| 53 | * "Dirty" flag - weather to build the tree if it wasn't compiled allready |
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| 54 | * @var boolean |
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| 55 | */ |
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| 56 | private $compiled = false; |
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| 57 | |||
| 58 | /** |
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| 59 | * Store all tree items |
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| 60 | * @var array - array([ID] => TreeBuilder\Branch, [ID] => TreeBuilder\Branch) |
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| 61 | */ |
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| 62 | private $branches = array(); |
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| 63 | |||
| 64 | /** |
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| 65 | * Stores the compiled tree |
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| 66 | * @var array |
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| 67 | */ |
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| 68 | private $compiledTree = array(); |
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| 69 | |||
| 70 | /** |
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| 71 | * A delagated adapter for the output |
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| 72 | * @var Adapter |
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| 73 | */ |
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| 74 | private $delegatedAdapter; |
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| 75 | |||
| 76 | /** |
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| 77 | * Defines the build mode off the tree |
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| 78 | * @var int |
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| 79 | */ |
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| 80 | private $buildMode; |
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| 81 | |||
| 82 | /** |
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| 83 | * Enables debug mode |
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| 84 | */ |
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| 85 | public function enableDebug() |
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| 89 | |||
| 90 | /** |
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| 91 | * Show debug state |
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| 92 | * @return boolean |
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| 93 | */ |
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| 94 | public function isDebugEnabled() |
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| 98 | |||
| 99 | /** |
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| 100 | * Get debug data |
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| 101 | * @return string |
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| 102 | * @throws \Exception |
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| 103 | */ |
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| 104 | public function getDebugData() |
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| 111 | |||
| 112 | /** |
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| 113 | * Delegate an adapter for the wanted output |
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| 114 | * @param Adapter $adapter |
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| 115 | * @return \TreeBuilder\Tree |
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| 116 | */ |
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| 117 | public function registerAdapter(Adapter $adapter) |
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| 122 | |||
| 123 | /** |
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| 124 | * Set the build mode identified by local constants |
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| 125 | * @param int $value |
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| 126 | * @return \TreeBuilder\Tree |
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| 127 | */ |
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| 128 | public function setBuildMode($value) |
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| 133 | |||
| 134 | /** |
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| 135 | * Add a new TreeItem |
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| 136 | * @param Branch $item |
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| 137 | */ |
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| 138 | public function addBranch(Branch $item) |
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| 143 | |||
| 144 | /** |
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| 145 | * Returns the builded tree |
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| 146 | * @return array |
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| 147 | */ |
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| 148 | public function getTree() |
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| 160 | |||
| 161 | /** |
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| 162 | * Return a branch by it's id |
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| 163 | * @param int $branchId |
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| 164 | * @return \TreeBuilder\Base\Branch |
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| 165 | * @throws \Exception |
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| 166 | */ |
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| 167 | public function getBranchById($branchId) |
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| 180 | |||
| 181 | /** |
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| 182 | * Return all leaf branches |
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| 183 | * @return array |
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| 184 | */ |
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| 185 | public function getLeafs() |
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| 195 | |||
| 196 | /** |
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| 197 | * Build the tree |
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| 198 | */ |
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| 199 | public function buildTree() |
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| 237 | |||
| 238 | /** |
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| 239 | * Build the tree parent->child references |
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| 240 | * @param int $branchId |
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| 241 | * @param Branch $item |
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| 242 | */ |
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| 243 | private function buildBranchReference($branchId, Branch $item) |
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| 259 | |||
| 260 | /** |
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| 261 | * Set the depth filed for items |
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| 262 | * @param array $items |
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| 263 | * @param int $depth |
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| 264 | */ |
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| 265 | private function addDepth(array $items, $depth = 0) |
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| 274 | |||
| 275 | /** |
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| 276 | * Add left->right fields to tree |
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| 277 | * @param array $items |
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| 278 | * @param int $left |
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| 279 | * @return int |
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| 280 | */ |
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| 281 | private function addLeftRight(array $items, $left = 1) |
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| 297 | |||
| 298 | /** |
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| 299 | * Mark leaf branches |
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| 300 | * @param array $items |
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| 301 | */ |
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| 302 | private function markLeafs($items) |
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| 312 | |||
| 313 | /** |
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| 314 | * Add to debug data |
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| 315 | * @param string $string |
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| 316 | */ |
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| 317 | private function logDebug($string) |
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| 321 | } |
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| 322 |
If you define a variable conditionally, it can happen that it is not defined for all execution paths.
Let’s take a look at an example:
In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
Define a default value for the variable:
Add a value for the missing path: