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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23 | class Diff extends ArrayObject implements DiffOp { |
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24 | |||
25 | /** |
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26 | * @var bool|null |
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27 | */ |
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28 | private $isAssociative = null; |
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29 | |||
30 | /** |
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31 | * Pointers to the operations of certain types for quick lookup. |
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32 | * |
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33 | * @var array[] |
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34 | */ |
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35 | private $typePointers = array( |
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36 | 'add' => array(), |
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37 | 'remove' => array(), |
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38 | 'change' => array(), |
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39 | 'list' => array(), |
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40 | 'map' => array(), |
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41 | 'diff' => array(), |
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42 | ); |
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43 | |||
44 | /** |
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45 | * @var int |
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46 | */ |
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47 | private $indexOffset = 0; |
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48 | |||
49 | /** |
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50 | * @since 0.1 |
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51 | * |
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52 | * @param DiffOp[] $operations |
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53 | * @param bool|null $isAssociative |
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54 | * |
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55 | * @throws InvalidArgumentException |
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56 | */ |
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57 | 105 | public function __construct( array $operations = array(), $isAssociative = null ) { |
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74 | |||
75 | /** |
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76 | * @since 0.1 |
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77 | * |
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78 | * @return DiffOp[] |
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79 | */ |
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80 | 122 | public function getOperations(): array { |
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83 | |||
84 | /** |
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85 | * @since 0.1 |
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86 | * |
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87 | * @param string $type |
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88 | * |
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89 | * @return DiffOp[] |
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90 | */ |
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91 | 21 | public function getTypeOperations( string $type ): array { |
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97 | |||
98 | /** |
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99 | * @since 0.1 |
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100 | * |
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101 | * @param DiffOp[] $operations |
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102 | */ |
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103 | 7 | public function addOperations( array $operations ) { |
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108 | |||
109 | /** |
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110 | * Gets called before a new element is added to the ArrayObject. |
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111 | * |
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112 | * At this point the index is always set (ie not null) and the |
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113 | * value is always of the type returned by @see getObjectType. |
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114 | * |
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115 | * Should return a boolean. When false is returned the element |
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116 | * does not get added to the ArrayObject. |
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117 | * |
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118 | * @param int|string $index |
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119 | * @param DiffOp $value |
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120 | * |
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121 | * @return bool |
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122 | * @throws InvalidArgumentException |
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123 | */ |
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124 | 84 | private function preSetElement( $index, DiffOp $value ): bool { |
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138 | |||
139 | /** |
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140 | * @see Serializable::unserialize |
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141 | * |
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142 | * @since 0.1 |
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143 | * |
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144 | * @param string $serialization |
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145 | */ |
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146 | 43 | public function unserialize( $serialization ) { |
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163 | |||
164 | /** |
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165 | * @since 0.1 |
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166 | * |
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167 | * @return DiffOpAdd[] |
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168 | */ |
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169 | 7 | public function getAdditions(): array { |
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172 | |||
173 | /** |
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174 | * @since 0.1 |
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175 | * |
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176 | * @return DiffOpRemove[] |
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177 | */ |
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178 | 7 | public function getRemovals(): array { |
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181 | |||
182 | /** |
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183 | * @since 0.1 |
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184 | * |
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185 | * @return DiffOpChange[] |
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186 | */ |
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187 | public function getChanges(): array { |
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190 | |||
191 | /** |
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192 | * Returns the added values. |
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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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206 | |||
207 | /** |
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208 | * Returns the removed values. |
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209 | * |
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210 | * @since 0.1 |
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211 | * |
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212 | * @return array of mixed |
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213 | */ |
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214 | 1 | public function getRemovedValues(): array { |
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222 | |||
223 | /** |
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224 | * @see DiffOp::isAtomic |
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225 | * |
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226 | * @since 0.1 |
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227 | * |
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228 | * @return bool |
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229 | */ |
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230 | 72 | public function isAtomic(): bool { |
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233 | |||
234 | /** |
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235 | * @see DiffOp::getType |
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236 | * |
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237 | * @since 0.1 |
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238 | * |
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239 | * @return string |
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240 | */ |
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241 | 152 | public function getType(): string { |
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244 | |||
245 | /** |
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246 | * Counts the number of atomic operations in the diff. |
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247 | * This means the size of a diff with as elements only empty diffs will be 0. |
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248 | * Or that the size of a diff with one atomic operation and one diff that itself |
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249 | * holds two atomic operations will be 3. |
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250 | * |
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251 | * @see Countable::count |
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252 | * |
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253 | * @since 0.1 |
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254 | * |
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255 | * @return int |
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256 | */ |
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257 | 84 | public function count(): int { |
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269 | |||
270 | /** |
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271 | * @since 0.3 |
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272 | */ |
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273 | 1 | public function removeEmptyOperations() { |
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280 | |||
281 | /** |
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282 | * Returns the value of the isAssociative flag. |
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283 | * |
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284 | * @since 0.4 |
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285 | * |
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286 | * @return bool|null |
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287 | */ |
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288 | 9 | public function isAssociative() { |
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291 | |||
292 | /** |
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293 | * Returns if the diff looks associative or not. |
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294 | * This first checks the isAssociative flag and in case its null checks |
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295 | * if there are any non-add-non-remove operations. |
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296 | * |
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297 | * @since 0.4 |
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298 | * |
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299 | * @return bool |
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300 | */ |
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301 | 9 | public function looksAssociative(): bool { |
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304 | |||
305 | /** |
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306 | * Returns if the diff can be non-associative. |
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307 | * This means it does not contain any non-add-non-remove operations. |
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308 | * |
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309 | * @since 0.4 |
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310 | * |
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311 | * @return bool |
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312 | */ |
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313 | 16 | public function hasAssociativeOperations(): bool { |
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319 | |||
320 | /** |
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321 | * Returns the Diff in array form where nested DiffOps are also turned into their array form. |
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322 | * |
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323 | * @see DiffOp::toArray |
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324 | * |
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325 | * @since 0.5 |
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326 | * |
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327 | * @param callable|null $valueConverter optional callback used to convert any |
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328 | * complex values to arrays. |
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329 | * |
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330 | * @return array |
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331 | */ |
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332 | 108 | public function toArray( callable $valueConverter = null ): array { |
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345 | |||
346 | /** |
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347 | * @since 2.0 |
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348 | * |
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349 | * @param mixed $target |
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350 | * |
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351 | * @return bool |
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352 | */ |
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353 | 12 | public function equals( $target ) { |
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365 | |||
366 | /** |
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367 | * Finds a new offset for when appending an element. |
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368 | * The base class does this, so it would be better to integrate, |
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369 | * but there does not appear to be any way to do this... |
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370 | * |
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371 | * @return int |
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372 | */ |
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373 | 23 | private function getNewOffset(): int { |
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380 | |||
381 | /** |
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382 | * @see ArrayObject::append |
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383 | * |
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384 | * @since 0.1 |
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385 | * |
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386 | * @param mixed $value |
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387 | */ |
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388 | 19 | public function append( $value ) { |
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391 | |||
392 | /** |
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393 | * @see ArrayObject::offsetSet() |
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394 | * |
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395 | * @since 0.1 |
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396 | * |
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397 | * @param int|string $index |
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398 | * @param mixed $value |
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399 | */ |
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400 | 72 | public function offsetSet( $index, $value ) { |
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403 | |||
404 | /** |
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405 | * Method that actually sets the element and holds |
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406 | * all common code needed for set operations, including |
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407 | * type checking and offset resolving. |
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408 | * |
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409 | * If you want to do additional indexing or have code that |
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410 | * otherwise needs to be executed whenever an element is added, |
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411 | * you can overload @see preSetElement. |
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412 | * |
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413 | * @param int|string|null $index |
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414 | * @param mixed $value |
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415 | * |
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416 | * @throws InvalidArgumentException |
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417 | */ |
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418 | 86 | private function setElement( $index, $value ) { |
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433 | |||
434 | /** |
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435 | * @see Serializable::serialize |
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436 | * |
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437 | * @since 0.1 |
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438 | * |
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439 | * @return string |
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440 | */ |
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441 | 43 | public function serialize() { |
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453 | |||
454 | /** |
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455 | * Returns if the ArrayObject has no elements. |
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456 | * |
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457 | * @since 0.1 |
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458 | * |
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459 | * @return bool |
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460 | */ |
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461 | 15 | public function isEmpty(): bool { |
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464 | |||
465 | } |
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466 |
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 theSon
calls the wrong method in the parent class.