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 Map 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 Map, and based on these observations, apply Extract Interface, too.
1 | <?php |
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14 | final class Map implements \IteratorAggregate, \ArrayAccess, Collection |
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15 | { |
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16 | use Traits\Collection; |
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17 | use Traits\SquaredCapacity; |
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18 | |||
19 | const MIN_CAPACITY = 8; |
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20 | |||
21 | /** |
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22 | * @var Pair[] |
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23 | */ |
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24 | private $internal = []; |
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25 | |||
26 | /** |
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27 | * Creates an instance using the values of an array or Traversable object. |
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28 | * |
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29 | * @param array|\Traversable|null $values |
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30 | */ |
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31 | public function __construct($values = null) |
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37 | |||
38 | /** |
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39 | * Updates all values by applying a callback function to each value. |
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40 | * |
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41 | * @param callable $callback Accepts two arguments: key and value, should |
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42 | * return what the updated value will be. |
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43 | */ |
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44 | public function apply(callable $callback) |
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50 | |||
51 | /** |
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52 | * @inheritDoc |
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53 | */ |
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54 | public function clear() |
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59 | |||
60 | /** |
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61 | * Return the first Pair from the Map |
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62 | * |
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63 | * @return Pair |
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64 | * |
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65 | * @throws UnderflowException |
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66 | */ |
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67 | public function first(): Pair |
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75 | |||
76 | /** |
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77 | * Return the last Pair from the Map |
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78 | * |
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79 | * @return Pair |
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80 | * |
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81 | * @throws UnderflowException |
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82 | */ |
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83 | public function last(): Pair |
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91 | |||
92 | /** |
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93 | * Return the pair at a specified position in the Map |
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94 | * |
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95 | * @param int $position |
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96 | * |
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97 | * @return Pair |
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98 | * |
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99 | * @throws OutOfRangeException |
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100 | */ |
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101 | public function skip(int $position): Pair |
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109 | |||
110 | /** |
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111 | * Merge an array of values with the current Map |
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112 | * |
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113 | * @param array|\Traversable $values |
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114 | * |
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115 | * @return Map |
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116 | */ |
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117 | public function merge($values): Map |
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124 | |||
125 | /** |
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126 | * Intersect |
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127 | * |
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128 | * @param Map $map |
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129 | * |
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130 | * @return Map |
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131 | */ |
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132 | public function intersect(Map $map): Map |
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138 | |||
139 | /** |
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140 | * Diff |
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141 | * |
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142 | * @param Map $map |
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143 | * |
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144 | * @return Map |
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145 | */ |
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146 | public function diff(Map $map): Map |
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152 | |||
153 | /** |
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154 | * Identical |
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155 | * |
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156 | * @param mixed $a |
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157 | * @param mixed $b |
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158 | * |
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159 | * @return bool |
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160 | */ |
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161 | private function keysAreEqual($a, $b): bool |
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169 | |||
170 | /** |
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171 | * @param $key |
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172 | * |
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173 | * @return Pair|null |
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174 | */ |
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175 | private function lookupKey($key) |
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183 | |||
184 | /** |
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185 | * @param $value |
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186 | * |
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187 | * @return Pair|null |
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188 | */ |
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189 | private function lookupValue($value) |
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197 | |||
198 | /** |
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199 | * Returns whether an association a given key exists. |
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200 | * |
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201 | * @param mixed $key |
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202 | * |
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203 | * @return bool |
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204 | */ |
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205 | public function hasKey($key): bool |
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209 | |||
210 | /** |
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211 | * Returns whether an association for a given value exists. |
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212 | * |
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213 | * @param mixed $value |
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214 | * |
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215 | * @return bool |
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216 | */ |
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217 | public function hasValue($value): bool |
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221 | |||
222 | /** |
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223 | * @inheritDoc |
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224 | */ |
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225 | public function count(): int |
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229 | |||
230 | /** |
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231 | * Returns a new map containing only the values for which a predicate |
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232 | * returns true. A boolean test will be used if a predicate is not provided. |
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233 | * |
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234 | * @param callable|null $callback Accepts a key and a value, and returns: |
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235 | * true : include the value, |
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236 | * false: skip the value. |
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237 | * |
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238 | * @return Map |
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239 | */ |
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240 | public function filter(callable $callback = null): Map |
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252 | |||
253 | /** |
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254 | * Returns the value associated with a key, or an optional default if the |
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255 | * key is not associated with a value. |
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256 | * |
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257 | * @param mixed $key |
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258 | * @param mixed $default |
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259 | * |
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260 | * @return mixed The associated value or fallback default if provided. |
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261 | * |
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262 | * @throws OutOfBoundsException if no default was provided and the key is |
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263 | * not associated with a value. |
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264 | */ |
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265 | public function get($key, $default = null) |
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277 | |||
278 | /** |
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279 | * Returns a set of all the keys in the map. |
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280 | * |
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281 | * @return Set |
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282 | */ |
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283 | public function keys(): Set |
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293 | |||
294 | /** |
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295 | * Returns a new map using the results of applying a callback to each value. |
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296 | * |
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297 | * The keys will be equal in both maps. |
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298 | * |
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299 | * @param callable $callback Accepts two arguments: key and value, should |
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300 | * return what the updated value will be. |
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301 | * |
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302 | * @return Map |
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303 | */ |
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304 | public function map(callable $callback): Map |
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314 | |||
315 | /** |
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316 | * Returns a sequence of pairs representing all associations. |
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317 | * |
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318 | * @return Sequence |
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319 | */ |
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320 | public function pairs(): Sequence |
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330 | |||
331 | /** |
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332 | * Associates a key with a value, replacing a previous association if there |
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333 | * was one. |
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334 | * |
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335 | * @param mixed $key |
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336 | * @param mixed $value |
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337 | */ |
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338 | public function put($key, $value) |
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350 | |||
351 | /** |
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352 | * Creates associations for all keys and corresponding values of either an |
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353 | * array or iterable object. |
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354 | * |
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355 | * @param \Traversable|array $values |
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356 | */ |
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357 | public function putAll($values) |
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363 | |||
364 | /** |
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365 | * Iteratively reduces the map to a single value using a callback. |
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366 | * |
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367 | * @param callable $callback Accepts the carry, key, and value, and |
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368 | * returns an updated carry value. |
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369 | * |
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370 | * @param mixed|null $initial Optional initial carry value. |
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371 | * |
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372 | * @return mixed The carry value of the final iteration, or the initial |
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373 | * value if the map was empty. |
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374 | */ |
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375 | public function reduce(callable $callback, $initial = null) |
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385 | |||
386 | /** |
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387 | * |
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388 | */ |
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389 | private function delete(int $position) |
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399 | |||
400 | /** |
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401 | * Removes a key's association from the map and returns the associated value |
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402 | * or a provided default if provided. |
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403 | * |
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404 | * @param mixed $key |
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405 | * @param mixed $default |
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406 | * |
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407 | * @return mixed The associated value or fallback default if provided. |
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408 | * |
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409 | * @throws \OutOfBoundsException if no default was provided and the key is |
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410 | * not associated with a value. |
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411 | */ |
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412 | public function remove($key, $default = null) |
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427 | |||
428 | /** |
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429 | * Returns a reversed copy of the map. |
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430 | */ |
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431 | public function reverse() |
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435 | |||
436 | /** |
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437 | * Returns a reversed copy of the map. |
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438 | */ |
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439 | public function reversed(): Map |
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446 | |||
447 | /** |
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448 | * Returns a sub-sequence of a given length starting at a specified offset. |
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449 | * |
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450 | * @param int $offset If the offset is non-negative, the map will |
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451 | * start at that offset in the map. If offset is |
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452 | * negative, the map will start that far from the |
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453 | * end. |
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454 | * |
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455 | * @param int|null $length If a length is given and is positive, the |
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456 | * resulting set will have up to that many pairs in |
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457 | * it. If the requested length results in an |
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458 | * overflow, only pairs up to the end of the map |
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459 | * will be included. |
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460 | * |
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461 | * If a length is given and is negative, the map |
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462 | * will stop that many pairs from the end. |
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463 | * |
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464 | * If a length is not provided, the resulting map |
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465 | * will contains all pairs between the offset and |
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466 | * the end of the map. |
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467 | * |
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468 | * @return Map |
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469 | */ |
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470 | public function slice(int $offset, int $length = null): Map |
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486 | |||
487 | /** |
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488 | * Sorts the map in-place, based on an optional callable comparator. |
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489 | * |
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490 | * The map will be sorted by value. |
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491 | * |
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492 | * @param callable|null $comparator Accepts two values to be compared. |
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493 | */ |
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494 | View Code Duplication | public function sort(callable $comparator = null) |
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507 | |||
508 | /** |
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509 | * Returns a sorted copy of the map, based on an optional callable |
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510 | * comparator. The map will be sorted by value. |
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511 | * |
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512 | * @param callable|null $comparator Accepts two values to be compared. |
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513 | * |
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514 | * @return Map |
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515 | */ |
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516 | View Code Duplication | public function sorted(callable $comparator = null): Map |
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533 | |||
534 | /** |
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535 | * Sorts the map in-place, based on an optional callable comparator. |
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536 | * |
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537 | * The map will be sorted by key. |
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538 | * |
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539 | * @param callable|null $comparator Accepts two keys to be compared. |
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540 | */ |
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541 | View Code Duplication | public function ksort(callable $comparator = null) |
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554 | |||
555 | /** |
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556 | * Returns a sorted copy of the map, based on an optional callable |
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557 | * comparator. The map will be sorted by key. |
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558 | * |
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559 | * @param callable|null $comparator Accepts two keys to be compared. |
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560 | * |
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561 | * @return Map |
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562 | */ |
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563 | View Code Duplication | public function ksorted(callable $comparator = null): Map |
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580 | |||
581 | /** |
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582 | * Returns the sum of all values in the map. |
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583 | * |
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584 | * @return int|float The sum of all the values in the map. |
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585 | */ |
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586 | public function sum() |
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590 | |||
591 | /** |
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592 | * @inheritDoc |
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593 | */ |
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594 | public function toArray(): array |
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604 | |||
605 | /** |
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606 | * Returns a sequence of all the associated values in the Map. |
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607 | * |
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608 | * @return Sequence |
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609 | */ |
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610 | public function values(): Sequence |
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620 | |||
621 | /** |
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622 | * |
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623 | * |
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624 | * @return \Ds\Map |
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625 | */ |
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626 | public function union(Map $map): Map |
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630 | |||
631 | /** |
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632 | * XOR |
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633 | * |
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634 | * @param Map $map |
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635 | * |
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636 | * @return Map |
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637 | */ |
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638 | public function xor(Map $map): Map |
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644 | |||
645 | /** |
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646 | * Get iterator |
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647 | */ |
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648 | public function getIterator() |
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654 | |||
655 | /** |
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656 | * Debug Info |
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657 | */ |
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658 | public function __debugInfo() |
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662 | |||
663 | /** |
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664 | * @inheritdoc |
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665 | */ |
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666 | public function offsetSet($offset, $value) |
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670 | |||
671 | /** |
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672 | * @inheritdoc |
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673 | * |
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674 | * @throws OutOfBoundsException |
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675 | */ |
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676 | public function &offsetGet($offset) |
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686 | |||
687 | /** |
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688 | * @inheritdoc |
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689 | */ |
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690 | public function offsetUnset($offset) |
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694 | |||
695 | /** |
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696 | * @inheritdoc |
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697 | */ |
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698 | public function offsetExists($offset) |
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702 | } |
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703 |
This check looks for multiple assignments in successive lines of code. It will report an issue if the operators are not in a straight line.
To visualize
will produce issues in the first and second line, while this second example
will produce no issues.