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 BitArray 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 BitArray, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 27 | class BitArray implements \ArrayAccess, \Countable, \IteratorAggregate, \JsonSerializable |
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| 28 | { |
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| 29 | /** |
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| 30 | * @var BitArray Empty bit array |
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| 31 | */ |
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| 32 | private static $empty; |
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| 33 | |||
| 34 | /** |
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| 35 | * @var integer[] Number of bits for each value between 0 and 255 |
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| 36 | */ |
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| 37 | private static $count = array( |
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| 38 | 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, |
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| 39 | 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
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| 40 | 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
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| 41 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 42 | 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
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| 43 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 44 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 45 | 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
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| 46 | 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
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| 47 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 48 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 49 | 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
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| 50 | 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
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| 51 | 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
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| 52 | 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
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| 53 | 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 |
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| 54 | ); |
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| 55 | |||
| 56 | /** |
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| 57 | * @var integer[] Mask for restricting complements |
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| 58 | */ |
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| 59 | private static $restrict = array(255, 1, 3, 7, 15, 31, 63, 127); |
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| 60 | |||
| 61 | /** |
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| 62 | * @var string Underlying data |
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| 63 | * |
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| 64 | * @since 1.0.0 |
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| 65 | */ |
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| 66 | private $data; |
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| 67 | |||
| 68 | /** |
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| 69 | * @var integer Size of the bit array |
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| 70 | * |
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| 71 | * @since 1.0.0 |
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| 72 | */ |
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| 73 | private $size; |
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| 74 | |||
| 75 | /** |
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| 76 | * Create a new bit array of the given size |
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| 77 | * |
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| 78 | * @param integer $size The BitArray size |
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| 79 | * @param boolean $default The default value for bits |
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| 80 | * |
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| 81 | * @since 1.0.0 |
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| 82 | */ |
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| 83 | protected function __construct($size = 0, $default = false) |
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| 97 | |||
| 98 | /** |
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| 99 | * Remove useless bits for simplifying count operation. |
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| 100 | * |
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| 101 | * @return BitArray $this for chaining |
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| 102 | * |
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| 103 | * @since 1.2.0 |
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| 104 | */ |
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| 105 | protected function restrict() |
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| 116 | |||
| 117 | /** |
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| 118 | * Clone a BitArray |
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| 119 | * |
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| 120 | * @return void |
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| 121 | * |
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| 122 | * @since 1.0.0 |
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| 123 | */ |
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| 124 | public function __clone() |
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| 128 | |||
| 129 | /** |
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| 130 | * Convert the object to a string |
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| 131 | * |
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| 132 | * @return string String representation of this object |
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| 133 | * |
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| 134 | * @since 1.0.0 |
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| 135 | */ |
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| 136 | public function __toString() |
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| 150 | |||
| 151 | /** |
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| 152 | * Magic get method |
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| 153 | * |
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| 154 | * @param string $property The property |
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| 155 | * |
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| 156 | * @throws \RuntimeException If the property does not exist |
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| 157 | * |
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| 158 | * @return mixed The value associated to the property |
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| 159 | * |
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| 160 | * @since 1.0.0 |
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| 161 | */ |
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| 162 | public function __get($property) |
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| 174 | |||
| 175 | /** |
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| 176 | * Test the existence of an index |
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| 177 | * |
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| 178 | * @param integer $offset The offset |
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| 179 | * |
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| 180 | * @return boolean The truth value |
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| 181 | * |
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| 182 | * @since 1.0.0 |
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| 183 | */ |
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| 184 | public function offsetExists($offset) |
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| 188 | |||
| 189 | /** |
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| 190 | * Get the truth value for an index |
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| 191 | * |
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| 192 | * @param integer $offset The offset |
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| 193 | * |
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| 194 | * @return boolean The truth value |
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| 195 | * |
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| 196 | * @throw \OutOfRangeException Argument index must be an positive integer lesser than the size |
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| 197 | * |
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| 198 | * @since 1.0.0 |
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| 199 | */ |
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| 200 | public function offsetGet($offset) |
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| 211 | |||
| 212 | /** |
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| 213 | * Set the truth value for an index |
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| 214 | * |
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| 215 | * @param integer $offset The offset |
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| 216 | * @param boolean $value The truth value |
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| 217 | * |
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| 218 | * @return void |
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| 219 | * |
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| 220 | * @throw \OutOfRangeException Argument index must be an positive integer lesser than the size |
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| 221 | * |
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| 222 | * @since 1.0.0 |
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| 223 | */ |
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| 224 | public function offsetSet($offset, $value) |
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| 244 | |||
| 245 | /** |
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| 246 | * Unset the existence of an index |
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| 247 | * |
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| 248 | * @param integer $offset The index |
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| 249 | * |
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| 250 | * @return void |
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| 251 | * |
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| 252 | * @throw \RuntimeException Values cannot be unset |
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| 253 | * |
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| 254 | * @since 1.0.0 |
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| 255 | */ |
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| 256 | public function offsetUnset($offset) |
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| 260 | |||
| 261 | /** |
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| 262 | * Return the number of true bits |
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| 263 | * |
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| 264 | * @return integer The number of true bits |
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| 265 | * |
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| 266 | * @since 1.0.0 |
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| 267 | */ |
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| 268 | public function count() |
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| 279 | |||
| 280 | /** |
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| 281 | * Transform the object to an array |
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| 282 | * |
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| 283 | * @return array Array of values |
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| 284 | * |
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| 285 | * @since 1.1.0 |
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| 286 | */ |
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| 287 | public function toArray() |
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| 298 | |||
| 299 | /** |
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| 300 | * Serialize the object |
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| 301 | * |
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| 302 | * @return array Array of values |
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| 303 | * |
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| 304 | * @since 1.0.0 |
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| 305 | */ |
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| 306 | public function jsonSerialize() |
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| 310 | |||
| 311 | /** |
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| 312 | * Get an iterator |
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| 313 | * |
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| 314 | * @return Iterator Iterator |
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| 315 | * |
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| 316 | * @since 1.0.0 |
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| 317 | */ |
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| 318 | public function getIterator() |
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| 322 | |||
| 323 | /** |
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| 324 | * Return the size |
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| 325 | * |
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| 326 | * @return integer The size |
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| 327 | * |
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| 328 | * @since 1.0.0 |
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| 329 | */ |
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| 330 | public function size() |
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| 334 | |||
| 335 | /** |
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| 336 | * Copy bits directly from a BitArray |
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| 337 | * |
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| 338 | * @param BitArray $bits A BitArray to copy |
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| 339 | * @param int $index Starting index for destination |
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| 340 | * @param int $offset Starting index for copying |
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| 341 | * @param int $size Copy size |
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| 342 | * |
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| 343 | * @return BitArray This object for chaining |
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| 344 | * |
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| 345 | * @throw \OutOfRangeException Argument index must be an positive integer lesser than the size |
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| 346 | * |
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| 347 | * @since 1.1.0 |
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| 348 | */ |
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| 349 | public function directCopy(BitArray $bits, $index = 0, $offset = 0, $size = 0) |
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| 368 | |||
| 369 | /** |
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| 370 | * Copy bits from a BitArray |
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| 371 | * |
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| 372 | * @param BitArray $bits A BitArray to copy |
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| 373 | * @param int $index Starting index for destination. |
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| 374 | * If index is non-negative, the index parameter is used as it is, keeping its real value between 0 and size-1. |
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| 375 | * If index is negative, the index parameter starts from the end, keeping its real value between 0 and size-1. |
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| 376 | * @param int $offset Starting index for copying. |
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| 377 | * If offset is non-negative, the offset parameter is used as it is, keeping its positive value between 0 and size-1. |
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| 378 | * If offset is negative, the offset parameter starts from the end, keeping its real value between 0 and size-1. |
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| 379 | * @param mixed $size Copy size. |
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| 380 | * If size is given and is positive, then the copy will copy size elements. |
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| 381 | * If the bits argument is shorter than the size, then only the available elements will be copied. |
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| 382 | * If size is given and is negative then the copy starts from the end. |
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| 383 | * If it is omitted, then the copy will have everything from offset up until the end of the bits argument. |
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| 384 | * |
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| 385 | * @return BitArray This object for chaining |
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| 386 | * |
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| 387 | * @since 1.1.0 |
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| 388 | */ |
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| 389 | public function copy(BitArray $bits, $index = 0, $offset = 0, $size = null) |
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| 402 | |||
| 403 | /** |
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| 404 | * Get the real offset using a positive or negative offset |
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| 405 | * |
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| 406 | * @param int $offset If offset is non-negative, the offset parameter is used as it is, keeping its real value between 0 and size-1. |
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| 407 | * If offset is negative, the offset parameter starts from the end, keeping its real value between 0 and size-1. |
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| 408 | * |
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| 409 | * @return integer The real offset |
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| 410 | * |
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| 411 | * @since 1.1.0 |
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| 412 | */ |
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| 413 | protected function getRealOffset($offset) |
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| 434 | |||
| 435 | /** |
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| 436 | * Get the real offset using a positive or negative offset |
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| 437 | * |
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| 438 | * @param int $offset The real offset. |
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| 439 | * @param mixed $size If size is given and is positive, then the real size will be between 0 and the current size-1. |
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| 440 | * If size is given and is negative then the real size starts from the end. |
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| 441 | * If it is omitted, then the size goes until the end of the BitArray. |
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| 442 | * |
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| 443 | * @return integer The real size |
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| 444 | * |
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| 445 | * @since 1.1.0 |
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| 446 | */ |
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| 447 | protected function getRealSize($offset, $size) |
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| 474 | |||
| 475 | /** |
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| 476 | * Create a new BitArray from an integer |
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| 477 | * |
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| 478 | * @param integer $size Size of the BitArray |
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| 479 | * @param boolean $default The default value for bits |
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| 480 | * |
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| 481 | * @return BitArray A new BitArray |
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| 482 | * |
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| 483 | * @since 1.0.0 |
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| 484 | */ |
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| 485 | public static function fromInteger($size, $default = false) |
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| 489 | |||
| 490 | /** |
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| 491 | * Create a new BitArray from a sequence of bits. |
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| 492 | * |
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| 493 | * @param integer $size Size of the BitArray |
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| 494 | * @param integer $values The values for the bits |
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| 495 | * |
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| 496 | * @return BitArray A new BitArray |
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| 497 | * |
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| 498 | * @since 1.2.0 |
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| 499 | */ |
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| 500 | public static function fromDecimal($size, $values = 0) |
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| 514 | |||
| 515 | /** |
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| 516 | * Create a new BitArray from a traversable |
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| 517 | * |
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| 518 | * @param \Traversable $traversable A traversable and countable |
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| 519 | * |
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| 520 | * @return BitArray A new BitArray |
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| 521 | * |
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| 522 | * @since 1.0.0 |
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| 523 | */ |
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| 524 | View Code Duplication | public static function fromTraversable($traversable) |
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| 553 | |||
| 554 | /** |
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| 555 | * Create a new BitArray from a bit string |
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| 556 | * |
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| 557 | * @param string $string A bit string |
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| 558 | * |
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| 559 | * @return BitArray A new BitArray |
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| 560 | * |
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| 561 | * @since 1.0.0 |
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| 562 | */ |
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| 563 | View Code Duplication | public static function fromString($string) |
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| 589 | |||
| 590 | /** |
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| 591 | * Create a new BitArray from json |
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| 592 | * |
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| 593 | * @param string $json A json encoded value |
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| 594 | * |
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| 595 | * @return BitArray A new BitArray |
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| 596 | * |
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| 597 | * @since 1.0.0 |
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| 598 | */ |
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| 599 | public static function fromJson($json) |
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| 603 | |||
| 604 | /** |
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| 605 | * Create a new BitArray using a slice |
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| 606 | * |
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| 607 | * @param BitArray $bits A BitArray to get the slice |
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| 608 | * @param int $offset If offset is non-negative, the slice will start at that offset in the bits argument. |
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| 609 | * If offset is negative, the slice will start from the end of the bits argument. |
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| 610 | * @param mixed $size If size is given and is positive, then the slice will have up to that many elements in it. |
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| 611 | * If the bits argument is shorter than the size, then only the available elements will be present. |
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| 612 | * If size is given and is negative then the slice will stop that many elements from the end of the bits argument. |
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| 613 | * If it is omitted, then the slice will have everything from offset up until the end of the bits argument. |
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| 614 | * |
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| 615 | * @return BitArray A new BitArray |
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| 616 | * |
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| 617 | * @since 1.1.0 |
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| 618 | */ |
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| 619 | public static function fromSlice(BitArray $bits, $offset = 0, $size = null) |
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| 627 | |||
| 628 | /** |
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| 629 | * Create a new BitArray using the concat operation |
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| 630 | * |
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| 631 | * @param BitArray $bits1 A BitArray |
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| 632 | * @param BitArray $bits2 A BitArray |
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| 633 | * |
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| 634 | * @return BitArray A new BitArray |
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| 635 | * |
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| 636 | * @since 1.1.0 |
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| 637 | */ |
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| 638 | public static function fromConcat(BitArray $bits1, BitArray $bits2) |
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| 647 | |||
| 648 | /** |
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| 649 | * Complement the bit array |
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| 650 | * |
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| 651 | * @return BitArray This object for chaining |
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| 652 | * |
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| 653 | * @since 1.0.0 |
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| 654 | */ |
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| 655 | public function applyComplement() |
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| 666 | |||
| 667 | /** |
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| 668 | * Or with an another bit array |
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| 669 | * |
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| 670 | * @param BitArray $bits A bit array |
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| 671 | * |
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| 672 | * @return BitArray This object for chaining |
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| 673 | * |
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| 674 | * @throw \InvalidArgumentException Argument must be of equal size |
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| 675 | * |
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| 676 | * @since 1.0.0 |
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| 677 | */ |
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| 678 | View Code Duplication | public function applyOr(BitArray $bits) |
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| 696 | |||
| 697 | /** |
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| 698 | * And with an another bit array |
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| 699 | * |
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| 700 | * @param BitArray $bits A bit array |
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| 701 | * |
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| 702 | * @return BitArray This object for chaining |
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| 703 | * |
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| 704 | * @throw \InvalidArgumentException Argument must be of equal size |
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| 705 | * |
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| 706 | * @since 1.0.0 |
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| 707 | */ |
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| 708 | View Code Duplication | public function applyAnd(BitArray $bits) |
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| 726 | |||
| 727 | /** |
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| 728 | * Xor with an another bit array |
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| 729 | * |
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| 730 | * @param BitArray $bits A bit array |
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| 731 | * |
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| 732 | * @return BitArray This object for chaining |
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| 733 | * |
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| 734 | * @throw \InvalidArgumentException Argument must be of equal size |
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| 735 | * |
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| 736 | * @since 1.0.0 |
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| 737 | */ |
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| 738 | View Code Duplication | public function applyXor(BitArray $bits) |
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| 756 | |||
| 757 | /** |
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| 758 | * Shift a bit array. |
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| 759 | * |
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| 760 | * @param int $size Size to shift. |
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| 761 | * Negative value means the shifting is done right to left while |
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| 762 | * positive value means the shifting is done left to right. |
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| 763 | * @param boolean $value Value to shift |
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| 764 | * |
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| 765 | * @return BitArray $this for chaining |
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| 766 | * |
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| 767 | * @since 1.2.0 |
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| 768 | */ |
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| 769 | public function shift($size = 1, $value = false) |
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| 804 | } |
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| 805 |
This check marks private properties in classes that are never used. Those properties can be removed.