Complex classes like Language 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 Language, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 37 | class Language implements JsonSerializable { | 
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| 38 | use  | 
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| 39 | Singleton;  | 
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| 40 | const INIT_STATE_METHOD = 'init';  | 
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| 41 | /**  | 
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| 42 | * Callable for time processing  | 
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| 43 | *  | 
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| 44 | * @var callable  | 
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| 45 | */  | 
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| 46 | public $time;  | 
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| 47 | /**  | 
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| 48 | * @var string  | 
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| 49 | */  | 
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| 50 | protected $current_language;  | 
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| 51 | /**  | 
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| 52 | * Local cache of translations  | 
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| 53 | *  | 
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| 54 | * @var array  | 
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| 55 | */  | 
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| 56 | protected $translation = [];  | 
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| 57 | /**  | 
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| 58 | * Cache to optimize frequent calls  | 
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| 59 | *  | 
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| 60 | * @var array  | 
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| 61 | */  | 
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| 62 | protected $localized_url = [];  | 
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| 63 | 62 | 	protected function init () { | 
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| 113 | /**  | 
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| 114 | * Returns instance for simplified work with translations, when using common prefix  | 
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| 115 | *  | 
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| 116 | * @param string $prefix  | 
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| 117 | *  | 
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| 118 | * @return Prefix  | 
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| 119 | */  | 
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| 120 | 22 | 	public static function prefix ($prefix) { | 
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| 123 | /**  | 
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| 124 | * Does URL have language prefix  | 
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| 125 | *  | 
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| 126 | * @param false|string $url Relative url, `Request::instance()->path` by default  | 
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| 127 | *  | 
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| 128 | * @return false|string If there is language prefix - language will be returned, `false` otherwise  | 
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| 129 | */  | 
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| 130 | 36 | 	public function url_language ($url = false) { | 
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| 149 | /**  | 
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| 150 | * Checking Accept-Language header for languages that exists in configuration  | 
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| 151 | *  | 
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| 152 | * @param array $active_languages  | 
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| 153 | *  | 
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| 154 | * @return false|string  | 
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| 155 | */  | 
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| 156 | 6 | 	protected function check_accept_header ($active_languages) { | 
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| 174 | /**  | 
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| 175 | * Check `*-Locale` header (for instance, `X-Facebook-Locale`) that exists in configuration  | 
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| 176 | *  | 
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| 177 | * @param string[] $active_languages  | 
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| 178 | *  | 
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| 179 | * @return false|string  | 
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| 180 | */  | 
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| 181 | 10 | 	protected function check_locale_header ($active_languages) { | 
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| 197 | /**  | 
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| 198 | * Get languages aliases  | 
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| 199 | *  | 
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| 200 | * @return array|false  | 
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| 201 | */  | 
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| 202 | 36 | 	protected function get_aliases () { | 
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| 218 | /**  | 
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| 219 | * Get translation  | 
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| 220 | *  | 
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| 221 | * @param bool|string $item  | 
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| 222 | * @param false|string $language If specified - translation for specified language will be returned, otherwise for current  | 
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| 223 | * @param string $prefix Used by `\cs\Language\Prefix`, usually no need to use it directly  | 
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| 224 | *  | 
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| 225 | * @return string  | 
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| 226 | */  | 
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| 227 | 54 | 	public function get ($item, $language = false, $prefix = '') { | 
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| 250 | /**  | 
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| 251 | * Set translation  | 
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| 252 | *  | 
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| 253 | * @param array|string $item Item string, or key-value array  | 
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| 254 | * @param null|string $value  | 
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| 255 | *  | 
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| 256 | * @return void  | 
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| 257 | */  | 
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| 258 | 	public function set ($item, $value = null) { | 
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| 266 | /**  | 
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| 267 | * Get translation  | 
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| 268 | *  | 
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| 269 | * @param string $item  | 
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| 270 | *  | 
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| 271 | * @return string  | 
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| 272 | */  | 
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| 273 | 54 | 	public function __get ($item) { | 
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| 276 | /**  | 
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| 277 | * Set translation  | 
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| 278 | *  | 
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| 279 | * @param array|string $item  | 
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| 280 | * @param null|string $value  | 
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| 281 | *  | 
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| 282 | * @return string  | 
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| 283 | */  | 
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| 284 | 	public function __set ($item, $value = null) { | 
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| 287 | /**  | 
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| 288 | * Change language  | 
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| 289 | *  | 
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| 290 | * @param string $language  | 
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| 291 | *  | 
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| 292 | * @return bool  | 
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| 293 | */  | 
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| 294 | 54 | 	public function change ($language) { | 
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| 325 | /**  | 
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| 326 | * Check whether it is allowed to change to specified language according to configuration  | 
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| 327 | *  | 
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| 328 | * @param Config $Config  | 
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| 329 | * @param string $language  | 
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| 330 | *  | 
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| 331 | * @return bool  | 
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| 332 | */  | 
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| 333 | 54 | 	protected function can_be_changed_to ($Config, $language) { | 
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| 356 | /**  | 
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| 357 | * Load translation from all over the system, set `$this->translation[$language]` and return it  | 
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| 358 | *  | 
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| 359 | * @param $language  | 
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| 360 | *  | 
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| 361 | * @return string[]  | 
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| 362 | */  | 
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| 363 | 10 | 	protected function get_translation_internal ($language) { | 
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| 403 | /**  | 
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| 404 | * @param string $filename  | 
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| 405 | *  | 
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| 406 | * @return string[]  | 
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| 407 | */  | 
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| 408 | 10 | 	protected function get_translation_from_json ($filename) { | 
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| 413 | /**  | 
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| 414 | * @param string[]|string[][] $translation  | 
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| 415 | *  | 
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| 416 | * @return string[]  | 
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| 417 | */  | 
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| 418 | 10 | 	protected function get_translation_from_json_internal ($translation) { | 
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| 431 | /**  | 
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| 432 | * Some required keys might be missing in translation, this functions tries to guess and fill them automatically  | 
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| 433 | *  | 
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| 434 | * @param string[] $translation  | 
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| 435 | * @param string $language  | 
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| 436 | *  | 
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| 437 | * @return string[]  | 
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| 438 | */  | 
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| 439 | 10 | 	protected function fill_required_translation_keys ($translation, $language) { | 
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| 451 | /**  | 
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| 452 | * Time formatting according to the current language (adding correct endings)  | 
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| 453 | *  | 
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| 454 | * @param int $in time (number)  | 
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| 455 | * @param string $type Type of formatting<br>  | 
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| 456 | * s - seconds<br>m - minutes<br>h - hours<br>d - days<br>M - months<br>y - years  | 
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| 457 | *  | 
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| 458 | * @return string  | 
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| 459 | */  | 
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| 460 | 4 | 	public function time ($in, $type) { | 
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| 482 | /**  | 
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| 483 | * Allows to use formatted strings in translations  | 
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| 484 | *  | 
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| 485 | * @see format()  | 
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| 486 | *  | 
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| 487 | * @param string $item  | 
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| 488 | * @param array $arguments  | 
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| 489 | *  | 
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| 490 | * @return string  | 
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| 491 | */  | 
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| 492 | 2 | 	public function __call ($item, $arguments) { | 
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| 495 | /**  | 
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| 496 | * Allows to use formatted strings in translations  | 
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| 497 | *  | 
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| 498 | * @param string $item  | 
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| 499 | * @param string[] $arguments  | 
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| 500 | * @param false|string $language If specified - translation for specified language will be returned, otherwise for current  | 
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| 501 | * @param string $prefix Used by `\cs\Language\Prefix`, usually no need to use it directly  | 
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| 502 | *  | 
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| 503 | * @return string  | 
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| 504 | */  | 
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| 505 | 6 | 	public function format ($item, $arguments, $language = false, $prefix = '') { | 
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| 508 | /**  | 
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| 509 | * Formatting date according to language locale (translating months names, days of week, etc.)  | 
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| 510 | *  | 
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| 511 | * @param string|string[] $data  | 
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| 512 | * @param bool $short_may When in date() or similar functions "M" format option is used, third month "May" have the same short textual  | 
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| 513 | * representation as full, so, this option allows to specify, which exactly form of representation do you want  | 
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| 514 | *  | 
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| 515 | * @return string|string[]  | 
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| 516 | */  | 
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| 517 | 2 | 	public function to_locale ($data, $short_may = false) { | 
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| 572 | /**  | 
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| 573 | * Implementation of JsonSerializable interface  | 
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| 574 | *  | 
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| 575 | * @return string[]  | 
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| 576 | */  | 
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| 577 | 4 | 	public function jsonSerialize () { | 
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| 580 | }  | 
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| 581 |