IcuCollation.php

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<?php
class IcuCollation extends Collation {
    const FIRST_LETTER_VERSION = 4;

    private $primaryCollator;

    private $mainCollator;

    private $locale;

    protected $digitTransformLanguage;

    private $useNumericCollation = false;

    private $firstLetterData;

    private static $cjkBlocks = [
        [ 0x2E80, 0x2EFF ], // CJK Radicals Supplement
        [ 0x2F00, 0x2FDF ], // Kangxi Radicals
        [ 0x2FF0, 0x2FFF ], // Ideographic Description Characters
        [ 0x3000, 0x303F ], // CJK Symbols and Punctuation
        [ 0x31C0, 0x31EF ], // CJK Strokes
        [ 0x3200, 0x32FF ], // Enclosed CJK Letters and Months
        [ 0x3300, 0x33FF ], // CJK Compatibility
        [ 0x3400, 0x4DBF ], // CJK Unified Ideographs Extension A
        [ 0x4E00, 0x9FFF ], // CJK Unified Ideographs
        [ 0xF900, 0xFAFF ], // CJK Compatibility Ideographs
        [ 0xFE30, 0xFE4F ], // CJK Compatibility Forms
        [ 0x20000, 0x2A6DF ], // CJK Unified Ideographs Extension B
        [ 0x2A700, 0x2B73F ], // CJK Unified Ideographs Extension C
        [ 0x2B740, 0x2B81F ], // CJK Unified Ideographs Extension D
        [ 0x2F800, 0x2FA1F ], // CJK Compatibility Ideographs Supplement
    ];

    private static $tailoringFirstLetters = [
        'af' => [],
        'am' => [],
        'ar' => [],
        'as' => [ "\u{0982}", "\u{0981}", "\u{0983}", "\u{09CE}", "ক্ষ " ],
        'ast' => [ "Ch", "Ll", "Ñ" ], // not in libicu
        'az' => [ "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ],
        'be' => [ "Ё" ],
        'be-tarask' => [ "Ё" ],
        'bg' => [],
        'bn' => [ 'ং', 'ঃ', 'ঁ' ],
        'bn@collation=traditional' => [
            'ং', 'ঃ', 'ঁ', 'ক্', 'খ্', 'গ্', 'ঘ্', 'ঙ্', 'চ্', 'ছ্', 'জ্', 'ঝ্',
            'ঞ্', 'ট্', 'ঠ্', 'ড্', 'ঢ্', 'ণ্', 'ৎ', 'থ্', 'দ্', 'ধ্', 'ন্', 'প্',
            'ফ্', 'ব্', 'ভ্', 'ম্', 'য্', 'র্', 'ৰ্', 'ল্', 'ৱ্', 'শ্', 'ষ্', 'স্', 'হ্'
        ],
        'bo' => [],
        'br' => [ "Ch", "C'h" ],
        'bs' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
        'bs-Cyrl' => [],
        'ca' => [],
        'chr' => [],
        'co' => [], // not in libicu
        'cs' => [ "Č", "Ch", "Ř", "Š", "Ž" ],
        'cy' => [ "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ],
        'da' => [ "Æ", "Ø", "Å" ],
        'de' => [],
        'de-AT@collation=phonebook' => [ 'ä', 'ö', 'ü', 'ß' ],
        'dsb' => [ "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ],
        'ee' => [ "Dz", "Ɖ", "Ɛ", "Ƒ", "Gb", "Ɣ", "Kp", "Ny", "Ŋ", "Ɔ", "Ts", "Ʋ" ],
        'el' => [],
        'en' => [],
        'eo' => [ "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ],
        'es' => [ "Ñ" ],
        'et' => [ "Š", "Ž", "Õ", "Ä", "Ö", "Ü" ],
        'eu' => [ "Ñ" ], // not in libicu
        'fa' => [
            // RTL, let's put each letter on a new line
            "آ",
            "ء",
            "ه",
            "ا",
            "و"
        ],
        'fi' => [ "Å", "Ä", "Ö" ],
        'fil' => [ "Ñ", "Ng" ],
        'fo' => [ "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ],
        'fr' => [],
        'fr-CA' => [], // fr-CA sorts accents slightly different from fr.
        'fur' => [ "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ], // not in libicu
        'fy' => [], // not in libicu
        'ga' => [],
        'gd' => [], // not in libicu
        'gl' => [ "Ch", "Ll", "Ñ" ],
        'gu' => [ "\u{0A82}", "\u{0A83}", "\u{0A81}", "\u{0AB3}" ],
        'ha' => [ 'Ɓ', 'Ɗ', 'Ƙ', 'Sh', 'Ts', 'Ƴ' ],
        'haw' => [ 'ʻ' ],
        'he' => [],
        'hi' => [ "\u{0902}", "\u{0903}" ],
        'hr' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
        'hsb' => [ "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ],
        'hu' => [ "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ],
        'hy' => [ "և" ],
        'id' => [],
        'ig' => [ "Ch", "Gb", "Gh", "Gw", "Ị", "Kp", "Kw", "Ṅ", "Nw", "Ny", "Ọ", "Sh", "Ụ" ],
        'is' => [ "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ],
        'it' => [],
        'ka' => [],
        'kk' => [ "Ү", "І" ],
        'kl' => [ "Æ", "Ø", "Å" ],
        'km' => [
            "រ", "ឫ", "ឬ", "ល", "ឭ", "ឮ", "\u{17BB}\u{17C6}",
            "\u{17C6}", "\u{17B6}\u{17C6}", "\u{17C7}",
            "\u{17B7}\u{17C7}", "\u{17BB}\u{17C7}",
            "\u{17C1}\u{17C7}", "\u{17C4}\u{17C7}",
        ],
        'kn' => [ "\u{0C81}", "\u{0C83}", "\u{0CF1}", "\u{0CF2}" ],
        'kok' => [ "\u{0902}", "\u{0903}", "ळ", "क्ष" ],
        'ku' => [ "Ç", "Ê", "Î", "Ş", "Û" ], // not in libicu
        'ky' => [ "Ё" ],
        'la' => [], // not in libicu
        'lb' => [],
        'lkt' => [ 'Č', 'Ǧ', 'Ȟ', 'Š', 'Ž' ],
        'ln' => [ 'Ɛ' ],
        'lo' => [],
        'lt' => [ "Č", "Š", "Ž" ],
        'lv' => [ "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ],
        'mk' => [ "Ѓ", "Ќ" ],
        'ml' => [],
        'mn' => [],
        'mo' => [ "Ă", "Â", "Î", "Ș", "Ț" ], // not in libicu
        'mr' => [ "\u{0902}", "\u{0903}", "ळ", "क्ष", "ज्ञ" ],
        'ms' => [],
        'mt' => [ "Ċ", "Ġ", "Għ", "Ħ", "Ż" ],
        'nb' => [ "Æ", "Ø", "Å" ],
        'ne' => [],
        'nl' => [],
        'nn' => [ "Æ", "Ø", "Å" ],
        'no' => [ "Æ", "Ø", "Å" ], // not in libicu. You should probably use nb or nn instead.
        'oc' => [], // not in libicu
        'om' => [ 'Ch', 'Dh', 'Kh', 'Ny', 'Ph', 'Sh' ],
        'or' => [ "\u{0B01}", "\u{0B02}", "\u{0B03}", "କ୍ଷ" ],
        'pa' => [ "\u{0A4D}" ],
        'pl' => [ "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ],
        'pt' => [],
        'rm' => [], // not in libicu
        'ro' => [ "Ă", "Â", "Î", "Ș", "Ț" ],
        'ru' => [],
        'rup' => [ "Ă", "Â", "Î", "Ľ", "Ń", "Ș", "Ț" ], // not in libicu
        'sco' => [],
        'se' => [
            'Á', 'Č', 'Ʒ', 'Ǯ', 'Đ', 'Ǧ', 'Ǥ', 'Ǩ', 'Ŋ',
            'Š', 'Ŧ', 'Ž', 'Ø', 'Æ', 'Ȧ', 'Ä', 'Ö'
        ],
        'si' => [ "\u{0D82}", "\u{0D83}", "\u{0DA4}" ],
        'sk' => [ "Ä", "Č", "Ch", "Ô", "Š", "Ž" ],
        'sl' => [ "Č", "Š", "Ž" ],
        'smn' => [ "Á", "Č", "Đ", "Ŋ", "Š", "Ŧ", "Ž", "Æ", "Ø", "Å", "Ä", "Ö" ],
        'sq' => [ "Ç", "Dh", "Ë", "Gj", "Ll", "Nj", "Rr", "Sh", "Th", "Xh", "Zh" ],
        'sr' => [],
        'sr-Latn' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
        'sv' => [ "Å", "Ä", "Ö" ],
        'sv@collation=standard' => [ "Å", "Ä", "Ö" ],
        'sw' => [],
        'ta' => [
            "\u{0B82}", "ஃ", "க்ஷ", "க்", "ங்", "ச்", "ஞ்", "ட்", "ண்", "த்", "ந்",
            "ப்", "ம்", "ய்", "ர்", "ல்", "வ்", "ழ்", "ள்", "ற்", "ன்", "ஜ்", "ஶ்", "ஷ்",
            "ஸ்", "ஹ்", "க்ஷ்"
        ],
        'te' => [ "\u{0C01}", "\u{0C02}", "\u{0C03}" ],
        'th' => [ "ฯ", "\u{0E46}", "\u{0E4D}", "\u{0E3A}" ],
        'tk' => [ "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ],
        'tl' => [ "Ñ", "Ng" ], // not in libicu
        'to' => [ "Ng", "ʻ" ],
        'tr' => [ "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ],
        '-tr' => [ "ı" ],
        'tt' => [ "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ], // not in libicu
        'uk' => [ "Ґ", "Ь" ],
        'uz' => [ "Ch", "G'", "Ng", "O'", "Sh" ], // not in libicu
        'vi' => [ "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ],
        'vo' => [ "Ä", "Ö", "Ü" ],
        'yi' => [
            "\u{05D1}\u{05BF}", "\u{05DB}\u{05BC}", "\u{05E4}\u{05BC}",
            "\u{05E9}\u{05C2}", "\u{05EA}\u{05BC}"
        ],
        'yo' => [ "Ẹ", "Gb", "Ọ", "Ṣ" ],
        'zu' => [],
    ];

    const RECORD_LENGTH = 14;

    public function __construct( $locale ) {
        if ( !extension_loaded( 'intl' ) ) {
            throw new MWException( 'An ICU collation was requested, ' .
                'but the intl extension is not available.' );
        }

        $this->locale = $locale;
        // Drop everything after the '@' in locale's name
        $localeParts = explode( '@', $locale );
        $this->digitTransformLanguage = Language::factory( $locale === 'root' ? 'en' : $localeParts[0] );

        $this->mainCollator = Collator::create( $locale );
        if ( !$this->mainCollator ) {
            throw new MWException( "Invalid ICU locale specified for collation: $locale" );
        }

        $this->primaryCollator = Collator::create( $locale );
        $this->primaryCollator->setStrength( Collator::PRIMARY );

        // If the special suffix for numeric collation is present, turn on numeric collation.
        if ( substr( $locale, -5, 5 ) === '-u-kn' ) {
            $this->useNumericCollation = true;
            // Strip off the special suffix so it doesn't trip up fetchFirstLetterData().
            $this->locale = substr( $this->locale, 0, -5 );
            $this->mainCollator->setAttribute( Collator::NUMERIC_COLLATION, Collator::ON );
            $this->primaryCollator->setAttribute( Collator::NUMERIC_COLLATION, Collator::ON );
        }
    }

    public function getSortKey( $string ) {
        return $this->mainCollator->getSortKey( $string );
    }

    public function getPrimarySortKey( $string ) {
        return $this->primaryCollator->getSortKey( $string );
    }

    public function getFirstLetter( $string ) {
        $string = strval( $string );
        if ( $string === '' ) {
            return '';
        }

        $firstChar = mb_substr( $string, 0, 1, 'UTF-8' );

        // If the first character is a CJK character, just return that character.
        if ( ord( $firstChar ) > 0x7f && self::isCjk( UtfNormal\Utils::utf8ToCodepoint( $firstChar ) ) ) {
            return $firstChar;
        }

        $sortKey = $this->getPrimarySortKey( $string );

        // Do a binary search to find the correct letter to sort under
        $min = ArrayUtils::findLowerBound(
            [ $this, 'getSortKeyByLetterIndex' ],
            $this->getFirstLetterCount(),
            'strcmp',
            $sortKey );

        if ( $min === false ) {
            // Before the first letter
            return '';
        }

        $sortLetter = $this->getLetterByIndex( $min );

        if ( $this->useNumericCollation ) {
            // If the sort letter is a number, return '0–9' (or localized equivalent).
            // ASCII value of 0 is 48. ASCII value of 9 is 57.
            // Note that this also applies to non-Arabic numerals since they are
            // mapped to Arabic numeral sort letters. For example, ২ sorts as 2.
            if ( ord( $sortLetter ) >= 48 && ord( $sortLetter ) <= 57 ) {
                $sortLetter = wfMessage( 'category-header-numerals' )->numParams( 0, 9 )->text();
            }
        }
        return $sortLetter;
    }

    public function getFirstLetterData() {
        if ( $this->firstLetterData === null ) {
            $cache = ObjectCache::getLocalServerInstance( CACHE_ANYTHING );
            $cacheKey = $cache->makeKey(
                'first-letters',
                static::class,
                $this->locale,
                $this->digitTransformLanguage->getCode(),
                INTL_ICU_VERSION,
                self::FIRST_LETTER_VERSION
            );
            $this->firstLetterData = $cache->getWithSetCallback( $cacheKey, $cache::TTL_WEEK, function () {
                return $this->fetchFirstLetterData();
            } );
        }
        return $this->firstLetterData;
    }

    private function fetchFirstLetterData() {
        global $IP;
        // Generate data from serialized data file
        if ( isset( self::$tailoringFirstLetters[$this->locale] ) ) {
            $letters = require "$IP/includes/collation/data/first-letters-root.php";
            // Append additional characters
            $letters = array_merge( $letters, self::$tailoringFirstLetters[$this->locale] );
            // Remove unnecessary ones, if any
            if ( isset( self::$tailoringFirstLetters['-' . $this->locale] ) ) {
                $letters = array_diff( $letters, self::$tailoringFirstLetters['-' . $this->locale] );
            }
            // Apply digit transforms
            $digits = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' ];
            $letters = array_diff( $letters, $digits );
            foreach ( $digits as $digit ) {
                $letters[] = $this->digitTransformLanguage->formatNum( $digit, true );
            }
        } elseif ( $this->locale === 'root' ) {
            $letters = require "$IP/includes/collation/data/first-letters-root.php";
        } else {
            // FIXME: Is this still used?
            $letters = wfGetPrecompiledData( "first-letters-{$this->locale}.ser" );
            if ( $letters === false ) {
                throw new MWException( "MediaWiki does not support ICU locale " .
                    "\"{$this->locale}\"" );
            }
        }

        /* Sort the letters.
         *
         * It's impossible to have the precompiled data file properly sorted,
         * because the sort order changes depending on ICU version. If the
         * array is not properly sorted, the binary search will return random
         * results.
         *
         * We also take this opportunity to remove primary collisions.
         */
        $letterMap = [];
        foreach ( $letters as $letter ) {
            $key = $this->getPrimarySortKey( $letter );
            if ( isset( $letterMap[$key] ) ) {
                // Primary collision (two characters with the same sort position).
                // Keep whichever one sorts first in the main collator.
                $comp = $this->mainCollator->compare( $letter, $letterMap[$key] );
                wfDebug( "Primary collision '$letter' '{$letterMap[$key]}' (comparison: $comp)\n" );
                // If that also has a collision, use codepoint as a tiebreaker.
                if ( $comp === 0 ) {
                    $comp = UtfNormal\Utils::utf8ToCodepoint( $letter ) <=>
                        UtfNormal\Utils::utf8ToCodepoint( $letterMap[$key] );
                }
                if ( $comp < 0 ) {
                    $letterMap[$key] = $letter;
                }
            } else {
                $letterMap[$key] = $letter;
            }
        }
        ksort( $letterMap, SORT_STRING );

        /* Remove duplicate prefixes. Basically if something has a sortkey
         * which is a prefix of some other sortkey, then it is an
         * expansion and probably should not be considered a section
         * header.
         *
         * For example 'þ' is sometimes sorted as if it is the letters
         * 'th'. Other times it is its own primary element. Another
         * example is '₨'. Sometimes its a currency symbol. Sometimes it
         * is an 'R' followed by an 's'.
         *
         * Additionally an expanded element should always sort directly
         * after its first element due to they way sortkeys work.
         *
         * UCA sortkey elements are of variable length but no collation
         * element should be a prefix of some other element, so I think
         * this is safe. See:
         * - https://ssl.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm
         * - http://site.icu-project.org/design/collation/uca-weight-allocation
         *
         * Additionally, there is something called primary compression to
         * worry about. Basically, if you have two primary elements that
         * are more than one byte and both start with the same byte then
         * the first byte is dropped on the second primary. Additionally
         * either \x03 or \xFF may be added to mean that the next primary
         * does not start with the first byte of the first primary.
         *
         * This shouldn't matter much, as the first primary is not
         * changed, and that is what we are comparing against.
         *
         * tl;dr: This makes some assumptions about how icu implements
         * collations. It seems incredibly unlikely these assumptions
         * will change, but nonetheless they are assumptions.
         */

        $prev = false;
        $duplicatePrefixes = [];
        foreach ( $letterMap as $key => $value ) {
            // Remove terminator byte. Otherwise the prefix
            // comparison will get hung up on that.
            $trimmedKey = rtrim( $key, "\0" );
            if ( $prev === false || $prev === '' ) {
                $prev = $trimmedKey;
                // We don't yet have a collation element
                // to compare against, so continue.
                continue;
            }

            // Due to the fact the array is sorted, we only have
            // to compare with the element directly previous
            // to the current element (skipping expansions).
            // An element "X" will always sort directly
            // before "XZ" (Unless we have "XY", but we
            // do not update $prev in that case).
            if ( substr( $trimmedKey, 0, strlen( $prev ) ) === $prev ) {
                $duplicatePrefixes[] = $key;
                // If this is an expansion, we don't want to
                // compare the next element to this element,
                // but to what is currently $prev
                continue;
            }
            $prev = $trimmedKey;
        }
        foreach ( $duplicatePrefixes as $badKey ) {
            wfDebug( "Removing '{$letterMap[$badKey]}' from first letters.\n" );
            unset( $letterMap[$badKey] );
            // This code assumes that unsetting does not change sort order.
        }
        $data = [
            'chars' => array_values( $letterMap ),
            'keys' => array_keys( $letterMap ),
        ];

        // Reduce memory usage before caching
        unset( $letterMap );

        return $data;
    }

    public function getLetterByIndex( $index ) {
        return $this->getFirstLetterData()['chars'][$index];
    }

    public function getSortKeyByLetterIndex( $index ) {
        return $this->getFirstLetterData()['keys'][$index];
    }

    public function getFirstLetterCount() {
        return count( $this->getFirstLetterData()['chars'] );
    }

    public static function isCjk( $codepoint ) {
        foreach ( self::$cjkBlocks as $block ) {
            if ( $codepoint >= $block[0] && $codepoint <= $block[1] ) {
                return true;
            }
        }
        return false;
    }

    static function getUnicodeVersionForICU() {
        $icuVersion = INTL_ICU_VERSION;
        if ( !$icuVersion ) {
            return false;
        }

        $versionPrefix = substr( $icuVersion, 0, 3 );
        // Source: http://site.icu-project.org/download
        $map = [
            '63.' => '11.0',
            '62.' => '11.0',
            '61.' => '10.0',
            '60.' => '10.0',
            '59.' => '9.0',
            '58.' => '9.0',
            '57.' => '8.0',
            '56.' => '8.0',
            '55.' => '7.0',
            '54.' => '7.0',
            '53.' => '6.3',
            '52.' => '6.3',
            '51.' => '6.2',
            '50.' => '6.2',
            '49.' => '6.1',
            '4.8' => '6.0',
            '4.6' => '6.0',
            '4.4' => '5.2',
            '4.2' => '5.1',
            '4.0' => '5.1',
            '3.8' => '5.0',
            '3.6' => '5.0',
            '3.4' => '4.1',
        ];

        return $map[$versionPrefix] ?? false;
    }
}