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   1  <?php
   2  /**
   3   * Database row sorting.
   4   *
   5   * This program is free software; you can redistribute it and/or modify
   6   * it under the terms of the GNU General Public License as published by
   7   * the Free Software Foundation; either version 2 of the License, or
   8   * (at your option) any later version.
   9   *
  10   * This program is distributed in the hope that it will be useful,
  11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13   * GNU General Public License for more details.
  14   *
  15   * You should have received a copy of the GNU General Public License along
  16   * with this program; if not, write to the Free Software Foundation, Inc.,
  17   * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18   * http://www.gnu.org/copyleft/gpl.html
  19   *
  20   * @file
  21   */
  22  
  23  abstract class Collation {
  24      private static $instance;
  25  
  26      /**
  27       * @return Collation
  28       */
  29  	static function singleton() {
  30          if ( !self::$instance ) {
  31              global $wgCategoryCollation;
  32              self::$instance = self::factory( $wgCategoryCollation );
  33          }
  34          return self::$instance;
  35      }
  36  
  37      /**
  38       * @throws MWException
  39       * @param string $collationName
  40       * @return Collation
  41       */
  42  	static function factory( $collationName ) {
  43          switch ( $collationName ) {
  44              case 'uppercase':
  45                  return new UppercaseCollation;
  46              case 'identity':
  47                  return new IdentityCollation;
  48              case 'uca-default':
  49                  return new IcuCollation( 'root' );
  50              case 'xx-uca-ckb':
  51                  return new CollationCkb;
  52              case 'xx-uca-et':
  53                  return new CollationEt;
  54              default:
  55                  $match = array();
  56                  if ( preg_match( '/^uca-([a-z@=-]+)$/', $collationName, $match ) ) {
  57                      return new IcuCollation( $match[1] );
  58                  }
  59  
  60                  # Provide a mechanism for extensions to hook in.
  61                  $collationObject = null;
  62                  wfRunHooks( 'Collation::factory', array( $collationName, &$collationObject ) );
  63  
  64                  if ( $collationObject instanceof Collation ) {
  65                      return $collationObject;
  66                  }
  67  
  68                  // If all else fails...
  69                  throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
  70          }
  71      }
  72  
  73      /**
  74       * Given a string, convert it to a (hopefully short) key that can be used
  75       * for efficient sorting.  A binary sort according to the sortkeys
  76       * corresponds to a logical sort of the corresponding strings.  Current
  77       * code expects that a line feed character should sort before all others, but
  78       * has no other particular expectations (and that one can be changed if
  79       * necessary).
  80       *
  81       * @param string $string UTF-8 string
  82       * @return string Binary sortkey
  83       */
  84      abstract function getSortKey( $string );
  85  
  86      /**
  87       * Given a string, return the logical "first letter" to be used for
  88       * grouping on category pages and so on.  This has to be coordinated
  89       * carefully with convertToSortkey(), or else the sorted list might jump
  90       * back and forth between the same "initial letters" or other pathological
  91       * behavior.  For instance, if you just return the first character, but "a"
  92       * sorts the same as "A" based on getSortKey(), then you might get a
  93       * list like
  94       *
  95       * == A ==
  96       * * [[Aardvark]]
  97       *
  98       * == a ==
  99       * * [[antelope]]
 100       *
 101       * == A ==
 102       * * [[Ape]]
 103       *
 104       * etc., assuming for the sake of argument that $wgCapitalLinks is false.
 105       *
 106       * @param string $string UTF-8 string
 107       * @return string UTF-8 string corresponding to the first letter of input
 108       */
 109      abstract function getFirstLetter( $string );
 110  }
 111  
 112  class UppercaseCollation extends Collation {
 113      private $lang;
 114  
 115  	function __construct() {
 116          // Get a language object so that we can use the generic UTF-8 uppercase
 117          // function there
 118          $this->lang = Language::factory( 'en' );
 119      }
 120  
 121  	function getSortKey( $string ) {
 122          return $this->lang->uc( $string );
 123      }
 124  
 125  	function getFirstLetter( $string ) {
 126          if ( $string[0] == "\0" ) {
 127              $string = substr( $string, 1 );
 128          }
 129          return $this->lang->ucfirst( $this->lang->firstChar( $string ) );
 130      }
 131  }
 132  
 133  /**
 134   * Collation class that's essentially a no-op.
 135   *
 136   * Does sorting based on binary value of the string.
 137   * Like how things were pre 1.17.
 138   */
 139  class IdentityCollation extends Collation {
 140  
 141  	function getSortKey( $string ) {
 142          return $string;
 143      }
 144  
 145  	function getFirstLetter( $string ) {
 146          global $wgContLang;
 147          // Copied from UppercaseCollation.
 148          // I'm kind of unclear on when this could happen...
 149          if ( $string[0] == "\0" ) {
 150              $string = substr( $string, 1 );
 151          }
 152          return $wgContLang->firstChar( $string );
 153      }
 154  }
 155  
 156  class IcuCollation extends Collation {
 157      const FIRST_LETTER_VERSION = 2;
 158  
 159      /** @var Collator */
 160      private $primaryCollator;
 161  
 162      /** @var Collator */
 163      private $mainCollator;
 164  
 165      /** @var string */
 166      private $locale;
 167  
 168      /** @var Language */
 169      protected $digitTransformLanguage;
 170  
 171      /** @var array */
 172      private $firstLetterData;
 173  
 174      /**
 175       * Unified CJK blocks.
 176       *
 177       * The same definition of a CJK block must be used for both Collation and
 178       * generateCollationData.php. These blocks are omitted from the first
 179       * letter data, as an optimisation measure and because the default UCA table
 180       * is pretty useless for sorting Chinese text anyway. Japanese and Korean
 181       * blocks are not included here, because they are smaller and more useful.
 182       */
 183      private static $cjkBlocks = array(
 184          array( 0x2E80, 0x2EFF ), // CJK Radicals Supplement
 185          array( 0x2F00, 0x2FDF ), // Kangxi Radicals
 186          array( 0x2FF0, 0x2FFF ), // Ideographic Description Characters
 187          array( 0x3000, 0x303F ), // CJK Symbols and Punctuation
 188          array( 0x31C0, 0x31EF ), // CJK Strokes
 189          array( 0x3200, 0x32FF ), // Enclosed CJK Letters and Months
 190          array( 0x3300, 0x33FF ), // CJK Compatibility
 191          array( 0x3400, 0x4DBF ), // CJK Unified Ideographs Extension A
 192          array( 0x4E00, 0x9FFF ), // CJK Unified Ideographs
 193          array( 0xF900, 0xFAFF ), // CJK Compatibility Ideographs
 194          array( 0xFE30, 0xFE4F ), // CJK Compatibility Forms
 195          array( 0x20000, 0x2A6DF ), // CJK Unified Ideographs Extension B
 196          array( 0x2A700, 0x2B73F ), // CJK Unified Ideographs Extension C
 197          array( 0x2B740, 0x2B81F ), // CJK Unified Ideographs Extension D
 198          array( 0x2F800, 0x2FA1F ), // CJK Compatibility Ideographs Supplement
 199      );
 200  
 201      /**
 202       * Additional characters (or character groups) to be considered separate
 203       * letters for given languages, or to be removed from the list of such
 204       * letters (denoted by keys starting with '-').
 205       *
 206       * These are additions to (or subtractions from) the data stored in the
 207       * first-letters-root.ser file (which among others includes full basic latin,
 208       * cyrillic and greek alphabets).
 209       *
 210       * "Separate letter" is a letter that would have a separate heading/section
 211       * for it in a dictionary or a phone book in this language. This data isn't
 212       * used for sorting (the ICU library handles that), only for deciding which
 213       * characters (or character groups) to use as headings.
 214       *
 215       * Initially generated based on the primary level of Unicode collation
 216       * tailorings available at http://developer.mimer.com/charts/tailorings.htm ,
 217       * later modified.
 218       *
 219       * Empty arrays are intended; this signifies that the data for the language is
 220       * available and that there are, in fact, no additional letters to consider.
 221       */
 222      private static $tailoringFirstLetters = array(
 223          // Verified by native speakers
 224          'be' => array( "Ё" ),
 225          'be-tarask' => array( "Ё" ),
 226          'cy' => array( "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ),
 227          'en' => array(),
 228          'fa' => array( "آ", "ء", "ه" ),
 229          'fi' => array( "Å", "Ä", "Ö" ),
 230          'fr' => array(),
 231          'hu' => array( "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ),
 232          'is' => array( "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ),
 233          'it' => array(),
 234          'lv' => array( "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ),
 235          'pl' => array( "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ),
 236          'pt' => array(),
 237          'ru' => array(),
 238          'sv' => array( "Å", "Ä", "Ö" ),
 239          'sv@collation=standard' => array( "Å", "Ä", "Ö" ),
 240          'uk' => array( "Ґ", "Ь" ),
 241          'vi' => array( "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ),
 242          // Not verified, but likely correct
 243          'af' => array(),
 244          'ast' => array( "Ch", "Ll", "Ñ" ),
 245          'az' => array( "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ),
 246          'bg' => array(),
 247          'br' => array( "Ch", "C'h" ),
 248          'bs' => array( "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ),
 249          'ca' => array(),
 250          'co' => array(),
 251          'cs' => array( "Č", "Ch", "Ř", "Š", "Ž" ),
 252          'da' => array( "Æ", "Ø", "Å" ),
 253          'de' => array(),
 254          'dsb' => array( "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ),
 255          'el' => array(),
 256          'eo' => array( "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ),
 257          'es' => array( "Ñ" ),
 258          'et' => array( "Š", "Ž", "Õ", "Ä", "Ö", "Ü", "W" ), // added W for CollationEt (xx-uca-et)
 259          'eu' => array( "Ñ" ),
 260          'fo' => array( "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ),
 261          'fur' => array( "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ),
 262          'fy' => array(),
 263          'ga' => array(),
 264          'gd' => array(),
 265          'gl' => array( "Ch", "Ll", "Ñ" ),
 266          'hr' => array( "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ),
 267          'hsb' => array( "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ),
 268          'kk' => array( "Ү", "І" ),
 269          'kl' => array( "Æ", "Ø", "Å" ),
 270          'ku' => array( "Ç", "Ê", "Î", "Ş", "Û" ),
 271          'ky' => array( "Ё" ),
 272          'la' => array(),
 273          'lb' => array(),
 274          'lt' => array( "Č", "Š", "Ž" ),
 275          'mk' => array(),
 276          'mo' => array( "Ă", "Â", "Î", "Ş", "Ţ" ),
 277          'mt' => array( "Ċ", "Ġ", "Għ", "Ħ", "Ż" ),
 278          'nl' => array(),
 279          'no' => array( "Æ", "Ø", "Å" ),
 280          'oc' => array(),
 281          'rm' => array(),
 282          'ro' => array( "Ă", "Â", "Î", "Ş", "Ţ" ),
 283          'rup' => array( "Ă", "Â", "Î", "Ľ", "Ń", "Ş", "Ţ" ),
 284          'sco' => array(),
 285          'sk' => array( "Ä", "Č", "Ch", "Ô", "Š", "Ž" ),
 286          'sl' => array( "Č", "Š", "Ž" ),
 287          'smn' => array( "Á", "Č", "Đ", "Ŋ", "Š", "Ŧ", "Ž", "Æ", "Ø", "Å", "Ä", "Ö" ),
 288          'sq' => array( "Ç", "Dh", "Ë", "Gj", "Ll", "Nj", "Rr", "Sh", "Th", "Xh", "Zh" ),
 289          'sr' => array(),
 290          'tk' => array( "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ),
 291          'tl' => array( "Ñ", "Ng" ),
 292          'tr' => array( "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ),
 293          'tt' => array( "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ),
 294          'uz' => array( "Ch", "G'", "Ng", "O'", "Sh" ),
 295      );
 296  
 297      const RECORD_LENGTH = 14;
 298  
 299  	function __construct( $locale ) {
 300          if ( !extension_loaded( 'intl' ) ) {
 301              throw new MWException( 'An ICU collation was requested, ' .
 302                  'but the intl extension is not available.' );
 303          }
 304  
 305          $this->locale = $locale;
 306          // Drop everything after the '@' in locale's name
 307          $localeParts = explode( '@', $locale );
 308          $this->digitTransformLanguage = Language::factory( $locale === 'root' ? 'en' : $localeParts[0] );
 309  
 310          $this->mainCollator = Collator::create( $locale );
 311          if ( !$this->mainCollator ) {
 312              throw new MWException( "Invalid ICU locale specified for collation: $locale" );
 313          }
 314  
 315          $this->primaryCollator = Collator::create( $locale );
 316          $this->primaryCollator->setStrength( Collator::PRIMARY );
 317      }
 318  
 319  	function getSortKey( $string ) {
 320          // intl extension produces non null-terminated
 321          // strings. Appending '' fixes it so that it doesn't generate
 322          // a warning on each access in debug php.
 323          wfSuppressWarnings();
 324          $key = $this->mainCollator->getSortKey( $string ) . '';
 325          wfRestoreWarnings();
 326          return $key;
 327      }
 328  
 329  	function getPrimarySortKey( $string ) {
 330          wfSuppressWarnings();
 331          $key = $this->primaryCollator->getSortKey( $string ) . '';
 332          wfRestoreWarnings();
 333          return $key;
 334      }
 335  
 336  	function getFirstLetter( $string ) {
 337          $string = strval( $string );
 338          if ( $string === '' ) {
 339              return '';
 340          }
 341  
 342          // Check for CJK
 343          $firstChar = mb_substr( $string, 0, 1, 'UTF-8' );
 344          if ( ord( $firstChar ) > 0x7f && self::isCjk( utf8ToCodepoint( $firstChar ) ) ) {
 345              return $firstChar;
 346          }
 347  
 348          $sortKey = $this->getPrimarySortKey( $string );
 349  
 350          // Do a binary search to find the correct letter to sort under
 351          $min = ArrayUtils::findLowerBound(
 352              array( $this, 'getSortKeyByLetterIndex' ),
 353              $this->getFirstLetterCount(),
 354              'strcmp',
 355              $sortKey );
 356  
 357          if ( $min === false ) {
 358              // Before the first letter
 359              return '';
 360          }
 361          return $this->getLetterByIndex( $min );
 362      }
 363  
 364  	function getFirstLetterData() {
 365          if ( $this->firstLetterData !== null ) {
 366              return $this->firstLetterData;
 367          }
 368  
 369          $cache = wfGetCache( CACHE_ANYTHING );
 370          $cacheKey = wfMemcKey(
 371              'first-letters',
 372              $this->locale,
 373              $this->digitTransformLanguage->getCode(),
 374              self::getICUVersion()
 375          );
 376          $cacheEntry = $cache->get( $cacheKey );
 377  
 378          if ( $cacheEntry && isset( $cacheEntry['version'] )
 379              && $cacheEntry['version'] == self::FIRST_LETTER_VERSION
 380          ) {
 381              $this->firstLetterData = $cacheEntry;
 382              return $this->firstLetterData;
 383          }
 384  
 385          // Generate data from serialized data file
 386  
 387          if ( isset( self::$tailoringFirstLetters[$this->locale] ) ) {
 388              $letters = wfGetPrecompiledData( "first-letters-root.ser" );
 389              // Append additional characters
 390              $letters = array_merge( $letters, self::$tailoringFirstLetters[$this->locale] );
 391              // Remove unnecessary ones, if any
 392              if ( isset( self::$tailoringFirstLetters['-' . $this->locale] ) ) {
 393                  $letters = array_diff( $letters, self::$tailoringFirstLetters['-' . $this->locale] );
 394              }
 395              // Apply digit transforms
 396              $digits = array( '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' );
 397              $letters = array_diff( $letters, $digits );
 398              foreach ( $digits as $digit ) {
 399                  $letters[] = $this->digitTransformLanguage->formatNum( $digit, true );
 400              }
 401          } else {
 402              $letters = wfGetPrecompiledData( "first-letters-{$this->locale}.ser" );
 403              if ( $letters === false ) {
 404                  throw new MWException( "MediaWiki does not support ICU locale " .
 405                      "\"{$this->locale}\"" );
 406              }
 407          }
 408  
 409          // Sort the letters.
 410          //
 411          // It's impossible to have the precompiled data file properly sorted,
 412          // because the sort order changes depending on ICU version. If the
 413          // array is not properly sorted, the binary search will return random
 414          // results.
 415          //
 416          // We also take this opportunity to remove primary collisions.
 417          $letterMap = array();
 418          foreach ( $letters as $letter ) {
 419              $key = $this->getPrimarySortKey( $letter );
 420              if ( isset( $letterMap[$key] ) ) {
 421                  // Primary collision
 422                  // Keep whichever one sorts first in the main collator
 423                  if ( $this->mainCollator->compare( $letter, $letterMap[$key] ) < 0 ) {
 424                      $letterMap[$key] = $letter;
 425                  }
 426              } else {
 427                  $letterMap[$key] = $letter;
 428              }
 429          }
 430          ksort( $letterMap, SORT_STRING );
 431          // Remove duplicate prefixes. Basically if something has a sortkey
 432          // which is a prefix of some other sortkey, then it is an
 433          // expansion and probably should not be considered a section
 434          // header.
 435          //
 436          // For example 'þ' is sometimes sorted as if it is the letters
 437          // 'th'. Other times it is its own primary element. Another
 438          // example is '₨'. Sometimes its a currency symbol. Sometimes it
 439          // is an 'R' followed by an 's'.
 440          //
 441          // Additionally an expanded element should always sort directly
 442          // after its first element due to they way sortkeys work.
 443          //
 444          // UCA sortkey elements are of variable length but no collation
 445          // element should be a prefix of some other element, so I think
 446          // this is safe. See:
 447          // * https://ssl.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm
 448          // * http://site.icu-project.org/design/collation/uca-weight-allocation
 449          //
 450          // Additionally, there is something called primary compression to
 451          // worry about. Basically, if you have two primary elements that
 452          // are more than one byte and both start with the same byte then
 453          // the first byte is dropped on the second primary. Additionally
 454          // either \x03 or \xFF may be added to mean that the next primary
 455          // does not start with the first byte of the first primary.
 456          //
 457          // This shouldn't matter much, as the first primary is not
 458          // changed, and that is what we are comparing against.
 459          //
 460          // tl;dr: This makes some assumptions about how icu implements
 461          // collations. It seems incredibly unlikely these assumptions
 462          // will change, but nonetheless they are assumptions.
 463  
 464          $prev = false;
 465          $duplicatePrefixes = array();
 466          foreach ( $letterMap as $key => $value ) {
 467              // Remove terminator byte. Otherwise the prefix
 468              // comparison will get hung up on that.
 469              $trimmedKey = rtrim( $key, "\0" );
 470              if ( $prev === false || $prev === '' ) {
 471                  $prev = $trimmedKey;
 472                  // We don't yet have a collation element
 473                  // to compare against, so continue.
 474                  continue;
 475              }
 476  
 477              // Due to the fact the array is sorted, we only have
 478              // to compare with the element directly previous
 479              // to the current element (skipping expansions).
 480              // An element "X" will always sort directly
 481              // before "XZ" (Unless we have "XY", but we
 482              // do not update $prev in that case).
 483              if ( substr( $trimmedKey, 0, strlen( $prev ) ) === $prev ) {
 484                  $duplicatePrefixes[] = $key;
 485                  // If this is an expansion, we don't want to
 486                  // compare the next element to this element,
 487                  // but to what is currently $prev
 488                  continue;
 489              }
 490              $prev = $trimmedKey;
 491          }
 492          foreach ( $duplicatePrefixes as $badKey ) {
 493              wfDebug( "Removing '{$letterMap[$badKey]}' from first letters.\n" );
 494              unset( $letterMap[$badKey] );
 495              // This code assumes that unsetting does not change sort order.
 496          }
 497          $data = array(
 498              'chars' => array_values( $letterMap ),
 499              'keys' => array_keys( $letterMap ),
 500              'version' => self::FIRST_LETTER_VERSION,
 501          );
 502  
 503          // Reduce memory usage before caching
 504          unset( $letterMap );
 505  
 506          // Save to cache
 507          $this->firstLetterData = $data;
 508          $cache->set( $cacheKey, $data, 86400 * 7 /* 1 week */ );
 509          return $data;
 510      }
 511  
 512  	function getLetterByIndex( $index ) {
 513          if ( $this->firstLetterData === null ) {
 514              $this->getFirstLetterData();
 515          }
 516          return $this->firstLetterData['chars'][$index];
 517      }
 518  
 519  	function getSortKeyByLetterIndex( $index ) {
 520          if ( $this->firstLetterData === null ) {
 521              $this->getFirstLetterData();
 522          }
 523          return $this->firstLetterData['keys'][$index];
 524      }
 525  
 526  	function getFirstLetterCount() {
 527          if ( $this->firstLetterData === null ) {
 528              $this->getFirstLetterData();
 529          }
 530          return count( $this->firstLetterData['chars'] );
 531      }
 532  
 533  	static function isCjk( $codepoint ) {
 534          foreach ( self::$cjkBlocks as $block ) {
 535              if ( $codepoint >= $block[0] && $codepoint <= $block[1] ) {
 536                  return true;
 537              }
 538          }
 539          return false;
 540      }
 541  
 542      /**
 543       * Return the version of ICU library used by PHP's intl extension,
 544       * or false when the extension is not installed of the version
 545       * can't be determined.
 546       *
 547       * The constant INTL_ICU_VERSION this function refers to isn't really
 548       * documented. It is available since PHP 5.3.7 (see PHP bug 54561).
 549       * This function will return false on older PHPs.
 550       *
 551       * @since 1.21
 552       * @return string|bool
 553       */
 554  	static function getICUVersion() {
 555          return defined( 'INTL_ICU_VERSION' ) ? INTL_ICU_VERSION : false;
 556      }
 557  
 558      /**
 559       * Return the version of Unicode appropriate for the version of ICU library
 560       * currently in use, or false when it can't be determined.
 561       *
 562       * @since 1.21
 563       * @return string|bool
 564       */
 565  	static function getUnicodeVersionForICU() {
 566          $icuVersion = IcuCollation::getICUVersion();
 567          if ( !$icuVersion ) {
 568              return false;
 569          }
 570  
 571          $versionPrefix = substr( $icuVersion, 0, 3 );
 572          // Source: http://site.icu-project.org/download
 573          $map = array(
 574              '50.' => '6.2',
 575              '49.' => '6.1',
 576              '4.8' => '6.0',
 577              '4.6' => '6.0',
 578              '4.4' => '5.2',
 579              '4.2' => '5.1',
 580              '4.0' => '5.1',
 581              '3.8' => '5.0',
 582              '3.6' => '5.0',
 583              '3.4' => '4.1',
 584          );
 585  
 586          if ( isset( $map[$versionPrefix] ) ) {
 587              return $map[$versionPrefix];
 588          } else {
 589              return false;
 590          }
 591      }
 592  }
 593  
 594  /**
 595   * Workaround for the lack of support of Sorani Kurdish / Central Kurdish language ('ckb') in ICU.
 596   *
 597   * Uses the same collation rules as Persian / Farsi ('fa'), but different characters for digits.
 598   */
 599  class CollationCkb extends IcuCollation {
 600  	function __construct() {
 601          // This will set $locale and collators, which affect the actual sorting order
 602          parent::__construct( 'fa' );
 603          // Override the 'fa' language set by parent constructor, which affects #getFirstLetterData()
 604          $this->digitTransformLanguage = Language::factory( 'ckb' );
 605      }
 606  }
 607  
 608  /**
 609   * Workaround for incorrect collation of Estonian language ('et') in ICU (bug 54168).
 610   *
 611   * 'W' and 'V' should not be considered the same letter for the purposes of collation in modern
 612   * Estonian. We work around this by replacing 'W' and 'w' with 'ᴡ' U+1D21 'LATIN LETTER SMALL
 613   * CAPITAL W' for sortkey generation, which is collated like 'W' and is not tailored to have the
 614   * same primary weight as 'V' in Estonian.
 615   */
 616  class CollationEt extends IcuCollation {
 617  	function __construct() {
 618          parent::__construct( 'et' );
 619      }
 620  
 621  	private static function mangle( $string ) {
 622          return str_replace(
 623              array( 'w', 'W' ),
 624              'ᴡ', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
 625              $string
 626          );
 627      }
 628  
 629  	private static function unmangle( $string ) {
 630          // Casing data is lost…
 631          return str_replace(
 632              'ᴡ', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
 633              'W',
 634              $string
 635          );
 636      }
 637  
 638  	function getSortKey( $string ) {
 639          return parent::getSortKey( self::mangle( $string ) );
 640      }
 641  
 642  	function getFirstLetter( $string ) {
 643          return self::unmangle( parent::getFirstLetter( self::mangle( $string ) ) );
 644      }
 645  }