Complex classes like PathIterator 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 PathIterator, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 9 | class PathIterator implements Iterator |
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| 10 | { |
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| 11 | const IS_MATCH = 'IS_MATCH'; |
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| 12 | const DESCENDANTS_COULD_MATCH = 'DESCENDANTS_COULD_MATCH'; |
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| 13 | const DESCENDANTS_CANT_MATCH = 'DESCENDANTS_CANT_MATCH'; |
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| 14 | |||
| 15 | /* |
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| 16 | * The list of return codes for filtering callback function |
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| 17 | */ |
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| 18 | /* |
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| 19 | * Valid elem, no filtering. |
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| 20 | */ |
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| 21 | const ELEMENT_IS_VALID = 1; // elem |
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| 22 | /* |
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| 23 | * Invalid elem and its descendants, so have to be filtered out. |
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| 24 | */ |
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| 25 | const ELEMENT_IS_INVALID = 2; |
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| 26 | /* |
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| 27 | * The same as `ELEMENT_IS_INVALID`. Additionaly after it sibling elems(and its descendants) have to be filtered out too. |
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| 28 | */ |
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| 29 | const SIBLINGS_ARE_INVALID = 3; |
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| 30 | |||
| 31 | protected $reader; |
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| 32 | protected $searchPath; |
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| 33 | protected $searchCrumbs; |
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| 34 | protected $crumbs; |
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| 35 | protected $currentDomExpansion; |
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| 36 | protected $rewindCount; |
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| 37 | protected $isValid; |
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| 38 | protected $returnType; |
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| 39 | |||
| 40 | /* |
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| 41 | * Filtering callback function |
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| 42 | */ |
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| 43 | protected $callback; |
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| 44 | |||
| 45 | public function __construct(ExceptionThrowingXMLReader $reader, $path, $returnType, $callback = null) |
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| 57 | |||
| 58 | public function current() |
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| 62 | |||
| 63 | public function key() |
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| 67 | |||
| 68 | public function next() |
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| 77 | |||
| 78 | public function rewind() |
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| 86 | |||
| 87 | public function valid() |
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| 91 | |||
| 92 | protected function getXMLObject() |
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| 116 | |||
| 117 | protected function pathIsMatching() |
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| 134 | |||
| 135 | protected function searchForOpenTag(XMLReader $r) |
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| 143 | |||
| 144 | public function tryGotoNextIterationElement() |
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| 205 | } |
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| 206 |
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: