Complex classes like Diff 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 Diff, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 25 | class Diff extends ArrayObject implements DiffOp { |
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| 26 | |||
| 27 | /** |
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| 28 | * @var bool|null |
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| 29 | */ |
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| 30 | private $isAssociative = null; |
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| 31 | |||
| 32 | /** |
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| 33 | * Pointers to the operations of certain types for quick lookup. |
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| 34 | * |
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| 35 | * @var array[] |
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| 36 | */ |
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| 37 | private $typePointers = array( |
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| 38 | 'add' => array(), |
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| 39 | 'remove' => array(), |
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| 40 | 'change' => array(), |
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| 41 | 'list' => array(), |
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| 42 | 'map' => array(), |
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| 43 | 'diff' => array(), |
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| 44 | ); |
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| 45 | |||
| 46 | /** |
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| 47 | * @var int |
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| 48 | */ |
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| 49 | private $indexOffset = 0; |
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| 50 | |||
| 51 | /** |
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| 52 | * @since 0.1 |
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| 53 | * |
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| 54 | * @param DiffOp[] $operations |
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| 55 | * @param bool|null $isAssociative |
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| 56 | * |
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| 57 | * @throws InvalidArgumentException |
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| 58 | */ |
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| 59 | 105 | public function __construct( array $operations = array(), $isAssociative = null ) { |
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| 76 | |||
| 77 | /** |
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| 78 | * @since 0.1 |
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| 79 | * |
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| 80 | * @return DiffOp[] |
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| 81 | */ |
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| 82 | 122 | public function getOperations(): array { |
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| 85 | |||
| 86 | /** |
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| 87 | * @since 0.1 |
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| 88 | * |
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| 89 | * @param string $type |
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| 90 | * |
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| 91 | * @return DiffOp[] |
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| 92 | */ |
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| 93 | 21 | public function getTypeOperations( string $type ): array { |
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| 99 | |||
| 100 | /** |
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| 101 | * @since 0.1 |
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| 102 | * |
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| 103 | * @param DiffOp[] $operations |
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| 104 | */ |
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| 105 | 7 | public function addOperations( array $operations ) { |
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| 110 | |||
| 111 | /** |
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| 112 | * Gets called before a new element is added to the ArrayObject. |
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| 113 | * |
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| 114 | * At this point the index is always set (ie not null) and the |
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| 115 | * value is always of the type returned by @see getObjectType. |
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| 116 | * |
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| 117 | * Should return a boolean. When false is returned the element |
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| 118 | * does not get added to the ArrayObject. |
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| 119 | * |
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| 120 | * @param int|string $index |
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| 121 | * @param DiffOp $value |
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| 122 | * |
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| 123 | * @return bool |
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| 124 | * @throws InvalidArgumentException |
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| 125 | */ |
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| 126 | 84 | private function preSetElement( $index, DiffOp $value ): bool { |
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| 140 | |||
| 141 | /** |
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| 142 | * @see Serializable::unserialize |
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| 143 | * |
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| 144 | * @since 0.1 |
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| 145 | * |
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| 146 | * @param string $serialization |
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| 147 | */ |
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| 148 | 43 | public function unserialize( $serialization ) { |
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| 165 | |||
| 166 | /** |
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| 167 | * @since 0.1 |
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| 168 | * |
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| 169 | * @return DiffOpAdd[] |
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| 170 | */ |
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| 171 | 7 | public function getAdditions(): array { |
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| 174 | |||
| 175 | /** |
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| 176 | * @since 0.1 |
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| 177 | * |
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| 178 | * @return DiffOpRemove[] |
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| 179 | */ |
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| 180 | 7 | public function getRemovals(): array { |
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| 183 | |||
| 184 | /** |
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| 185 | * @since 0.1 |
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| 186 | * |
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| 187 | * @return DiffOpChange[] |
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| 188 | */ |
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| 189 | public function getChanges(): array { |
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| 192 | |||
| 193 | /** |
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| 194 | * @since 0.1 |
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| 195 | * |
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| 196 | * @return array of mixed |
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| 197 | */ |
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| 198 | 1 | public function getAddedValues(): array { |
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| 199 | 1 | return array_map( |
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| 200 | 1 | function( DiffOpAdd $addition ) { |
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| 201 | 1 | return $addition->getNewValue(); |
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| 202 | 1 | }, |
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| 203 | 1 | $this->getTypeOperations( 'add' ) |
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| 204 | ); |
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| 205 | } |
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| 206 | |||
| 207 | /** |
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| 208 | * @since 0.1 |
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| 209 | * |
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| 210 | * @return array of mixed |
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| 211 | */ |
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| 212 | 1 | public function getRemovedValues(): array { |
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| 220 | |||
| 221 | /** |
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| 222 | * @see DiffOp::isAtomic |
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| 223 | * |
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| 224 | * @since 0.1 |
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| 225 | * |
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| 226 | * @return bool |
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| 227 | */ |
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| 228 | 72 | public function isAtomic(): bool { |
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| 231 | |||
| 232 | /** |
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| 233 | * @see DiffOp::getType |
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| 234 | * |
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| 235 | * @since 0.1 |
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| 236 | * |
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| 237 | * @return string |
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| 238 | */ |
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| 239 | 152 | public function getType(): string { |
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| 242 | |||
| 243 | /** |
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| 244 | * Counts the number of atomic operations in the diff. |
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| 245 | * This means the size of a diff with as elements only empty diffs will be 0. |
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| 246 | * Or that the size of a diff with one atomic operation and one diff that itself |
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| 247 | * holds two atomic operations will be 3. |
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| 248 | * |
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| 249 | * @see Countable::count |
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| 250 | * |
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| 251 | * @since 0.1 |
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| 252 | * |
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| 253 | * @return int |
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| 254 | */ |
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| 255 | 74 | public function count(): int { |
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| 267 | |||
| 268 | /** |
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| 269 | * @since 0.3 |
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| 270 | */ |
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| 271 | 1 | public function removeEmptyOperations() { |
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| 278 | |||
| 279 | /** |
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| 280 | * Returns the value of the isAssociative flag. |
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| 281 | * |
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| 282 | * @since 0.4 |
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| 283 | * |
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| 284 | * @return bool|null |
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| 285 | */ |
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| 286 | 9 | public function isAssociative() { |
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| 289 | |||
| 290 | /** |
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| 291 | * Returns if the diff looks associative or not. |
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| 292 | * This first checks the isAssociative flag and in case its null checks |
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| 293 | * if there are any non-add-non-remove operations. |
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| 294 | * |
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| 295 | * @since 0.4 |
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| 296 | * |
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| 297 | * @return bool |
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| 298 | */ |
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| 299 | 9 | public function looksAssociative(): bool { |
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| 302 | |||
| 303 | /** |
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| 304 | * Returns if the diff can be non-associative. |
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| 305 | * This means it does not contain any non-add-non-remove operations. |
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| 306 | * |
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| 307 | * @since 0.4 |
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| 308 | * |
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| 309 | * @return bool |
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| 310 | */ |
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| 311 | 16 | public function hasAssociativeOperations(): bool { |
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| 317 | |||
| 318 | /** |
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| 319 | * Returns the Diff in array form where nested DiffOps are also turned into their array form. |
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| 320 | * |
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| 321 | * @see DiffOp::toArray |
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| 322 | * |
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| 323 | * @since 0.5 |
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| 324 | * |
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| 325 | * @param callable|null $valueConverter optional callback used to convert any |
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| 326 | * complex values to arrays. |
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| 327 | * |
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| 328 | * @return array |
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| 329 | */ |
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| 330 | 108 | public function toArray( callable $valueConverter = null ): array { |
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| 343 | |||
| 344 | /** |
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| 345 | * @since 2.0 |
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| 346 | * |
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| 347 | * @param mixed $target |
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| 348 | * |
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| 349 | * @return bool |
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| 350 | */ |
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| 351 | 12 | public function equals( $target ) { |
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| 363 | |||
| 364 | /** |
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| 365 | * Finds a new offset for when appending an element. |
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| 366 | * The base class does this, so it would be better to integrate, |
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| 367 | * but there does not appear to be any way to do this... |
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| 368 | * |
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| 369 | * @return int |
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| 370 | */ |
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| 371 | 23 | private function getNewOffset(): int { |
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| 378 | |||
| 379 | /** |
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| 380 | * @see ArrayObject::append |
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| 381 | * |
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| 382 | * @since 0.1 |
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| 383 | * |
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| 384 | * @param mixed $value |
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| 385 | */ |
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| 386 | 19 | public function append( $value ) { |
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| 389 | |||
| 390 | /** |
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| 391 | * @see ArrayObject::offsetSet() |
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| 392 | * |
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| 393 | * @since 0.1 |
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| 394 | * |
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| 395 | * @param int|string $index |
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| 396 | * @param mixed $value |
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| 397 | */ |
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| 398 | 72 | public function offsetSet( $index, $value ) { |
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| 401 | |||
| 402 | /** |
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| 403 | * Method that actually sets the element and holds |
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| 404 | * all common code needed for set operations, including |
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| 405 | * type checking and offset resolving. |
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| 406 | * |
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| 407 | * If you want to do additional indexing or have code that |
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| 408 | * otherwise needs to be executed whenever an element is added, |
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| 409 | * you can overload @see preSetElement. |
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| 410 | * |
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| 411 | * @param int|string|null $index |
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| 412 | * @param mixed $value |
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| 413 | * |
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| 414 | * @throws InvalidArgumentException |
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| 415 | */ |
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| 416 | 86 | private function setElement( $index, $value ) { |
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| 431 | |||
| 432 | /** |
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| 433 | * @see Serializable::serialize |
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| 434 | * |
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| 435 | * @since 0.1 |
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| 436 | * |
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| 437 | * @return string |
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| 438 | */ |
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| 439 | 43 | public function serialize() { |
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| 451 | |||
| 452 | /** |
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| 453 | * @since 0.1 |
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| 454 | * |
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| 455 | * @return bool |
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| 456 | */ |
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| 457 | 15 | public function isEmpty(): bool { |
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| 467 | |||
| 468 | } |
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| 469 |
This check looks for a call to a parent method whose name is different than the method from which it is called.
Consider the following code:
The
getFirstName()method in theSoncalls the wrong method in the parent class.