Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like ApiCollection 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 ApiCollection, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 14 | class ApiCollection extends AbstractLazyCollection implements Selectable  | 
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| 15 | { | 
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| 16 | /** @var ApiEntityManager */  | 
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| 17 | private $manager;  | 
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| 18 | /** @var ApiMetadata */  | 
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| 19 | private $metadata;  | 
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| 20 | /** @var object */  | 
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| 21 | private $owner;  | 
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| 22 | /** @var array */  | 
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| 23 | private $association;  | 
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| 24 | /** @var bool */  | 
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| 25 | private $isDirty = false;  | 
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| 26 | /** @var array */  | 
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| 27 | private $snapshot = [];  | 
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| 28 | /** @var string */  | 
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| 29 | private $backRefFieldName;  | 
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| 30 | |||
| 31 | /**  | 
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| 32 | * ApiCollection constructor.  | 
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| 33 | *  | 
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| 34 | * @param ApiEntityManager $manager  | 
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| 35 | * @param ApiMetadata $class  | 
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| 36 | * @param Collection $collection  | 
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| 37 | */  | 
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| 38 | 11 | public function __construct(  | 
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| 48 | |||
| 49 | /**  | 
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| 50 | * @return boolean  | 
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| 51 | */  | 
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| 52 | 2 | public function isDirty()  | 
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| 56 | |||
| 57 | 2 | public function unwrap()  | 
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| 61 | |||
| 62 | /**  | 
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| 63 | * INTERNAL:  | 
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| 64 | * Tells this collection to take a snapshot of its current state.  | 
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| 65 | *  | 
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| 66 | * @return void  | 
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| 67 | */  | 
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| 68 | 4 | public function takeSnapshot()  | 
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| 73 | |||
| 74 | 2 | public function getMapping()  | 
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| 78 | |||
| 79 | /**  | 
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| 80 | * @return object  | 
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| 81 | */  | 
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| 82 | 3 | public function getOwner()  | 
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| 86 | |||
| 87 | /**  | 
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| 88 | * @param object $owner  | 
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| 89 | * @param array $assoc  | 
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| 90 | */  | 
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| 91 | 11 | public function setOwner($owner, array $assoc)  | 
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| 97 | |||
| 98 | /**  | 
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| 99 | * @param bool $dirty  | 
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| 100 | */  | 
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| 101 | 2 | public function setDirty($dirty)  | 
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| 105 | |||
| 106 | /**  | 
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| 107 | * Initializes the collection by loading its contents from the database  | 
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| 108 | * if the collection is not yet initialized.  | 
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| 109 | *  | 
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| 110 | * @return void  | 
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| 111 | */  | 
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| 112 | 4 | public function initialize()  | 
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| 120 | |||
| 121 | /**  | 
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| 122 | * @return ApiMetadata  | 
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| 123 | */  | 
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| 124 | public function getMetadata()  | 
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| 128 | |||
| 129 | /**  | 
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| 130 | * INTERNAL:  | 
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| 131 | * Adds an element to a collection during hydration. This will automatically  | 
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| 132 | * complete bidirectional associations in the case of a one-to-many association.  | 
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| 133 | *  | 
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| 134 | * @param mixed $element The element to add.  | 
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| 135 | *  | 
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| 136 | * @return void  | 
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| 137 | */  | 
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| 138 | public function hydrateAdd($element)  | 
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| 156 | |||
| 157 | /**  | 
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| 158 | * INTERNAL:  | 
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| 159 | * Sets a keyed element in the collection during hydration.  | 
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| 160 | *  | 
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| 161 | * @param mixed $key The key to set.  | 
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| 162 | * @param mixed $element The element to set.  | 
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| 163 | *  | 
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| 164 | * @return void  | 
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| 165 | */  | 
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| 166 | public function hydrateSet($key, $element)  | 
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| 179 | |||
| 180 | /**  | 
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| 181 | * INTERNAL:  | 
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| 182 | * Returns the last snapshot of the elements in the collection.  | 
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| 183 | *  | 
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| 184 | * @return array The last snapshot of the elements.  | 
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| 185 | */  | 
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| 186 | public function getSnapshot()  | 
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| 190 | |||
| 191 | 9 | public function setInitialized($state)  | 
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| 195 | |||
| 196 | /**  | 
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| 197 | * INTERNAL:  | 
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| 198 | * getDeleteDiff  | 
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| 199 | *  | 
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| 200 | * @return array  | 
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| 201 | */  | 
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| 202 | View Code Duplication | public function getDeleteDiff()  | 
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| 212 | |||
| 213 | /**  | 
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| 214 | * INTERNAL:  | 
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| 215 | * getInsertDiff  | 
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| 216 | *  | 
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| 217 | * @return array  | 
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| 218 | */  | 
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| 219 | View Code Duplication | public function getInsertDiff()  | 
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| 229 | |||
| 230 | /**  | 
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| 231 |      * {@inheritdoc} | 
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| 232 | */  | 
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| 233 | View Code Duplication | public function remove($key)  | 
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| 250 | |||
| 251 | /**  | 
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| 252 |      * {@inheritdoc} | 
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| 253 | */  | 
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| 254 | 1 | public function removeElement($element)  | 
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| 282 | |||
| 283 | /**  | 
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| 284 |      * {@inheritdoc} | 
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| 285 | */  | 
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| 286 | View Code Duplication | public function containsKey($key)  | 
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| 298 | |||
| 299 | /**  | 
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| 300 |      * {@inheritdoc} | 
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| 301 | */  | 
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| 302 | 1 | View Code Duplication | public function contains($element)  | 
            
| 312 | |||
| 313 | /**  | 
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| 314 |      * {@inheritdoc} | 
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| 315 | */  | 
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| 316 | public function get($key)  | 
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| 333 | |||
| 334 | /**  | 
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| 335 |      * {@inheritdoc} | 
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| 336 | */  | 
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| 337 | 1 | public function count()  | 
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| 347 | |||
| 348 | /**  | 
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| 349 |      * {@inheritdoc} | 
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| 350 | */  | 
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| 351 | View Code Duplication | public function set($key, $value)  | 
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| 359 | |||
| 360 | /**  | 
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| 361 |      * {@inheritdoc} | 
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| 362 | */  | 
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| 363 | 2 | View Code Duplication | public function add($value)  | 
            
| 373 | |||
| 374 | /**  | 
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| 375 |      * {@inheritdoc} | 
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| 376 | */  | 
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| 377 | public function offsetExists($offset)  | 
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| 381 | |||
| 382 | /**  | 
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| 383 |      * {@inheritdoc} | 
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| 384 | */  | 
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| 385 | public function offsetGet($offset)  | 
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| 389 | /* ArrayAccess implementation */  | 
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| 390 | |||
| 391 | /**  | 
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| 392 |      * {@inheritdoc} | 
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| 393 | */  | 
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| 394 | public function offsetSet($offset, $value)  | 
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| 402 | |||
| 403 | /**  | 
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| 404 |      * {@inheritdoc} | 
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| 405 | */  | 
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| 406 | public function offsetUnset($offset)  | 
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| 410 | |||
| 411 | /**  | 
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| 412 |      * {@inheritdoc} | 
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| 413 | */  | 
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| 414 | 2 | public function isEmpty()  | 
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| 418 | |||
| 419 | /**  | 
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| 420 |      * {@inheritdoc} | 
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| 421 | */  | 
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| 422 | public function clear()  | 
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| 447 | |||
| 448 | /**  | 
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| 449 | * Called by PHP when this collection is serialized. Ensures that only the  | 
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| 450 | * elements are properly serialized.  | 
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| 451 | *  | 
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| 452 | * Internal note: Tried to implement Serializable first but that did not work well  | 
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| 453 | * with circular references. This solution seems simpler and works well.  | 
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| 454 | *  | 
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| 455 | * @return array  | 
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| 456 | */  | 
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| 457 | public function __sleep()  | 
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| 461 | |||
| 462 | /**  | 
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| 463 | * Extracts a slice of $length elements starting at position $offset from the Collection.  | 
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| 464 | *  | 
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| 465 | * If $length is null it returns all elements from $offset to the end of the Collection.  | 
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| 466 | * Keys have to be preserved by this method. Calling this method will only return the  | 
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| 467 | * selected slice and NOT change the elements contained in the collection slice is called on.  | 
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| 468 | *  | 
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| 469 | * @param int $offset  | 
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| 470 | * @param int|null $length  | 
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| 471 | *  | 
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| 472 | * @return array  | 
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| 473 | */  | 
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| 474 | View Code Duplication | public function slice($offset, $length = null)  | 
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| 484 | |||
| 485 | /**  | 
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| 486 | * Cleans up internal state of cloned persistent collection.  | 
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| 487 | *  | 
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| 488 | * The following problems have to be prevented:  | 
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| 489 | * 1. Added entities are added to old PC  | 
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| 490 | * 2. New collection is not dirty, if reused on other entity nothing  | 
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| 491 | * changes.  | 
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| 492 | * 3. Snapshot leads to invalid diffs being generated.  | 
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| 493 | * 4. Lazy loading grabs entities from old owner object.  | 
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| 494 | * 5. New collection is connected to old owner and leads to duplicate keys.  | 
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| 495 | *  | 
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| 496 | * @return void  | 
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| 497 | */  | 
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| 498 | public function __clone()  | 
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| 508 | |||
| 509 | /**  | 
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| 510 | * Selects all elements from a selectable that match the expression and  | 
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| 511 | * return a new collection containing these elements.  | 
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| 512 | *  | 
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| 513 | * @param \Doctrine\Common\Collections\Criteria $criteria  | 
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| 514 | *  | 
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| 515 | * @return Collection  | 
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| 516 | *  | 
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| 517 | * @throws \RuntimeException  | 
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| 518 | */  | 
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| 519 | public function matching(Criteria $criteria)  | 
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| 538 | |||
| 539 | /**  | 
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| 540 | * Do the initialization logic  | 
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| 541 | *  | 
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| 542 | * @return void  | 
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| 543 | * @throws RpcExceptionInterface  | 
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| 544 | */  | 
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| 545 | 2 | protected function doInitialize()  | 
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| 563 | |||
| 564 | /**  | 
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| 565 | * Marks this collection as changed/dirty.  | 
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| 566 | *  | 
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| 567 | * @return void  | 
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| 568 | */  | 
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| 569 | 3 | private function changed()  | 
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| 573 | }  | 
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| 574 | 
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.