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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| 33 | class Language implements JsonSerializable { | 
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| 34 | use Singleton;  | 
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| 35 | /**  | 
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| 36 | * Callable for time processing  | 
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| 37 | *  | 
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| 38 | * @var callable  | 
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| 39 | */  | 
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| 40 | public $time;  | 
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| 41 | /**  | 
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| 42 | * @var string  | 
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| 43 | */  | 
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| 44 | protected $current_language;  | 
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| 45 | /**  | 
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| 46 | * For single initialization  | 
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| 47 | *  | 
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| 48 | * @var bool  | 
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| 49 | */  | 
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| 50 | protected $init = false;  | 
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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 | /**  | 
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| 64 | * Set basic language  | 
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| 65 | */  | 
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| 66 | 	protected function construct () { | 
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| 95 | /**  | 
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| 96 | * Initialization: set default language based on system configuration and request-specific parameters  | 
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| 97 | */  | 
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| 98 | 	protected function init () { | 
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| 120 | /**  | 
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| 121 | * Returns instance for simplified work with translations, when using common prefix  | 
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| 122 | *  | 
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| 123 | * @param string $prefix  | 
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| 124 | *  | 
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| 125 | * @return Prefix  | 
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| 126 | */  | 
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| 127 | 	static function prefix ($prefix) { | 
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| 130 | /**  | 
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| 131 | * Does URL have language prefix  | 
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| 132 | *  | 
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| 133 | * @param false|string $url Relative url, `Request::instance()->path` by default  | 
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| 134 | *  | 
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| 135 | * @return false|string If there is language prefix - language will be returned, `false` otherwise  | 
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| 136 | */  | 
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| 137 | 32 | 	function url_language ($url = false) { | 
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| 156 | /**  | 
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| 157 | * Checking Accept-Language header for languages that exists in configuration  | 
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| 158 | *  | 
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| 159 | * @param array $active_languages  | 
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| 160 | *  | 
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| 161 | * @return false|string  | 
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| 162 | */  | 
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| 163 | 	protected function check_accept_header ($active_languages) { | 
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| 181 | /**  | 
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| 182 | * Check `*-Locale` header (for instance, `X-Facebook-Locale`) that exists in configuration  | 
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| 183 | *  | 
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| 184 | * @param string[] $active_languages  | 
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| 185 | *  | 
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| 186 | * @return false|string  | 
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| 187 | */  | 
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| 188 | 	protected function check_locale_header ($active_languages) { | 
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| 204 | /**  | 
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| 205 | * Get languages aliases  | 
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| 206 | *  | 
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| 207 | * @return array|false  | 
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| 208 | */  | 
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| 209 | 	protected function get_aliases () { | 
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| 222 | /**  | 
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| 223 | * Get translation  | 
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| 224 | *  | 
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| 225 | * @param bool|string $item  | 
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| 226 | * @param false|string $language If specified - translation for specified language will be returned, otherwise for current  | 
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| 227 | * @param string $prefix Used by `\cs\Language\Prefix`, usually no need to use it directly  | 
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| 228 | *  | 
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| 229 | * @return string  | 
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| 230 | */  | 
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| 231 | 	function get ($item, $language = false, $prefix = '') { | 
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| 248 | /**  | 
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| 249 | * Set translation  | 
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| 250 | *  | 
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| 251 | * @param array|string $item Item string, or key-value array  | 
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| 252 | * @param null|string $value  | 
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| 253 | *  | 
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| 254 | * @return void  | 
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| 255 | */  | 
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| 256 | 	function set ($item, $value = null) { | 
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| 264 | /**  | 
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| 265 | * Get translation  | 
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| 266 | *  | 
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| 267 | * @param string $item  | 
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| 268 | *  | 
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| 269 | * @return string  | 
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| 270 | */  | 
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| 271 | 	function __get ($item) { | 
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| 274 | /**  | 
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| 275 | * Set translation  | 
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| 276 | *  | 
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| 277 | * @param array|string $item  | 
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| 278 | * @param null|string $value  | 
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| 279 | *  | 
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| 280 | * @return string  | 
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| 281 | */  | 
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| 282 | 	function __set ($item, $value = null) { | 
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| 285 | /**  | 
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| 286 | * Will set language, but not actually change to it until requested for the first time  | 
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| 287 | *  | 
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| 288 | * @param string $language  | 
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| 289 | */  | 
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| 290 | 	protected function set_language ($language) { | 
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| 293 | /**  | 
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| 294 | * Change language  | 
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| 295 | *  | 
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| 296 | * @param string $language  | 
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| 297 | *  | 
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| 298 | * @return bool  | 
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| 299 | */  | 
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| 300 | 	function change ($language) { | 
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| 338 | /**  | 
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| 339 | * Check whether it is allowed to change to specified language according to configuration  | 
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| 340 | *  | 
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| 341 | * @param Config $Config  | 
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| 342 | * @param string $language  | 
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| 343 | *  | 
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| 344 | * @return bool  | 
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| 345 | */  | 
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| 346 | 	protected function can_be_changed_to ($Config, $language) { | 
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| 358 | /**  | 
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| 359 | * Load translation from all over the system, set `$this->translation[$language]` and return it  | 
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| 360 | *  | 
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| 361 | * @param $language  | 
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| 362 | *  | 
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| 363 | * @return string[]  | 
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| 364 | */  | 
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| 365 | 	protected function get_translation ($language) { | 
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| 396 | /**  | 
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| 397 | * @param string $filename  | 
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| 398 | *  | 
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| 399 | * @return string[]  | 
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| 400 | */  | 
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| 401 | 	protected function get_translation_from_json ($filename) { | 
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| 405 | /**  | 
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| 406 | * @param string[]|string[][] $translation  | 
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| 407 | *  | 
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| 408 | * @return string[]  | 
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| 409 | */  | 
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| 410 | 	protected function get_translation_from_json_internal ($translation) { | 
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| 423 | /**  | 
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| 424 | * Some required keys might be missing in translation, this functions tries to guess and fill them automatically  | 
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| 425 | *  | 
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| 426 | * @param string[] $translation  | 
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| 427 | * @param string $language  | 
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| 428 | *  | 
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| 429 | * @return string[]  | 
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| 430 | */  | 
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| 431 | 	protected function fill_required_translation_keys ($translation, $language) { | 
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| 443 | /**  | 
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| 444 | * Time formatting according to the current language (adding correct endings)  | 
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| 445 | *  | 
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| 446 | * @param int $in time (number)  | 
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| 447 | * @param string $type Type of formatting<br>  | 
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| 448 | * s - seconds<br>m - minutes<br>h - hours<br>d - days<br>M - months<br>y - years  | 
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| 449 | *  | 
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| 450 | * @return string  | 
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| 451 | */  | 
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| 452 | 	function time ($in, $type) { | 
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| 474 | /**  | 
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| 475 | * Allows to use formatted strings in translations  | 
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| 476 | *  | 
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| 477 | * @see format()  | 
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| 478 | *  | 
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| 479 | * @param string $item  | 
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| 480 | * @param array $arguments  | 
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| 481 | *  | 
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| 482 | * @return string  | 
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| 483 | */  | 
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| 484 | 	function __call ($item, $arguments) { | 
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| 487 | /**  | 
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| 488 | * Allows to use formatted strings in translations  | 
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| 489 | *  | 
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| 490 | * @param string $item  | 
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| 491 | * @param string[] $arguments  | 
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| 492 | * @param false|string $language If specified - translation for specified language will be returned, otherwise for current  | 
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| 493 | * @param string $prefix Used by `\cs\Language\Prefix`, usually no need to use it directly  | 
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| 494 | *  | 
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| 495 | * @return string  | 
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| 496 | */  | 
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| 497 | 	function format ($item, $arguments, $language = false, $prefix = '') { | 
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| 500 | /**  | 
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| 501 | * Formatting date according to language locale (translating months names, days of week, etc.)  | 
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| 502 | *  | 
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| 503 | * @param string|string[] $data  | 
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| 504 | * @param bool $short_may When in date() or similar functions "M" format option is used, third month "May" have the same short textual  | 
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| 505 | * representation as full, so, this option allows to specify, which exactly form of representation do you want  | 
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| 506 | *  | 
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| 507 | * @return string|string[]  | 
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| 508 | */  | 
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| 509 | 	function to_locale ($data, $short_may = false) { | 
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| 564 | /**  | 
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| 565 | * Implementation of JsonSerializable interface  | 
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| 566 | *  | 
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| 567 | * @return string[]  | 
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| 568 | */  | 
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| 569 | 	function jsonSerialize () { | 
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| 572 | }  | 
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| 573 | 
This check compares the return type specified in the
@returnannotation of a function or method doc comment with the types returned by the function and raises an issue if they mismatch.