Collation.php

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<?php
abstract class Collation {
    static $instance;

    static function singleton() {
        if ( !self::$instance ) {
            global $wgCategoryCollation;
            self::$instance = self::factory( $wgCategoryCollation );
        }
        return self::$instance;
    }

    static function factory( $collationName ) {
        switch ( $collationName ) {
            case 'uppercase':
                return new UppercaseCollation;
            case 'identity':
                return new IdentityCollation;
            case 'uca-default':
                return new IcuCollation( 'root' );
            default:
                $match = array();
                if ( preg_match( '/^uca-([a-z@=-]+)$/', $collationName, $match ) ) {
                    return new IcuCollation( $match[1] );
                }

                # Provide a mechanism for extensions to hook in.
                $collationObject = null;
                wfRunHooks( 'Collation::factory', array( $collationName, &$collationObject ) );

                if ( $collationObject instanceof Collation ) {
                    return $collationObject;
                }

                // If all else fails...
                throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
        }
    }

    abstract function getSortKey( $string );

    abstract function getFirstLetter( $string );
}

class UppercaseCollation extends Collation {
    var $lang;
    function __construct() {
        // Get a language object so that we can use the generic UTF-8 uppercase
        // function there
        $this->lang = Language::factory( 'en' );
    }

    function getSortKey( $string ) {
        return $this->lang->uc( $string );
    }

    function getFirstLetter( $string ) {
        if ( $string[0] == "\0" ) {
            $string = substr( $string, 1 );
        }
        return $this->lang->ucfirst( $this->lang->firstChar( $string ) );
    }
}

class IdentityCollation extends Collation {

    function getSortKey( $string ) {
        return $string;
    }

    function getFirstLetter( $string ) {
        global $wgContLang;
        // Copied from UppercaseCollation.
        // I'm kind of unclear on when this could happen...
        if ( $string[0] == "\0" ) {
            $string = substr( $string, 1 );
        }
        return $wgContLang->firstChar( $string );
    }
}

class IcuCollation extends Collation {
    const FIRST_LETTER_VERSION = 1;

    var $primaryCollator, $mainCollator, $locale;
    var $firstLetterData;

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

    static $tailoringFirstLetters = array(
        // Verified by native speakers
        'be' => array( "Ё" ),
        'be-tarask' => array( "Ё" ),
        'en' => array(),
        'fi' => array( "Å", "Ä", "Ö" ),
        'hu' => array( "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ),
        'it' => array(),
        'pl' => array( "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ),
        'pt' => array(),
        'ru' => array(),
        'sv' => array( "Å", "Ä", "Ö" ),
        'sv@collation=standard' => array( "Å", "Ä", "Ö" ),
        'uk' => array( "Ґ", "Ь" ),
        'vi' => array( "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ),
        // Not verified, but likely correct
        'af' => array(),
        'ast' => array( "Ch", "Ll", "Ñ" ),
        'az' => array( "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ),
        'bg' => array(),
        'br' => array( "Ch", "C'h" ),
        'bs' => array( "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ),
        'ca' => array(),
        'co' => array(),
        'cs' => array( "Č", "Ch", "Ř", "Š", "Ž" ),
        'cy' => array( "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ),
        'da' => array( "Æ", "Ø", "Å" ),
        'de' => array(),
        'dsb' => array( "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ),
        'el' => array(),
        'eo' => array( "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ),
        'es' => array( "Ñ" ),
        'et' => array( "Š", "Ž", "Õ", "Ä", "Ö", "Ü" ),
        'eu' => array( "Ñ" ),
        'fa' => array( "آ", "ء", "ه" ),
        'fo' => array( "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ),
        'fr' => array(),
        'fur' => array( "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ),
        'fy' => array(),
        'ga' => array(),
        'gd' => array(),
        'gl' => array( "Ch", "Ll", "Ñ" ),
        'hr' => array( "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ),
        'hsb' => array( "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ),
        'is' => array( "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ),
        'kk' => array( "Ү", "І" ),
        'kl' => array( "Æ", "Ø", "Å" ),
        'ku' => array( "Ç", "Ê", "Î", "Ş", "Û" ),
        'ky' => array( "Ё" ),
        'la' => array(),
        'lb' => array(),
        'lt' => array( "Č", "Š", "Ž" ),
        'lv' => array( "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ),
        'mk' => array(),
        'mo' => array( "Ă", "Â", "Î", "Ş", "Ţ" ),
        'mt' => array( "Ċ", "Ġ", "Għ", "Ħ", "Ż" ),
        'nl' => array(),
        'no' => array( "Æ", "Ø", "Å" ),
        'oc' => array(),
        'rm' => array(),
        'ro' => array( "Ă", "Â", "Î", "Ş", "Ţ" ),
        'rup' => array( "Ă", "Â", "Î", "Ľ", "Ń", "Ş", "Ţ" ),
        'sco' => array(),
        'sk' => array( "Ä", "Č", "Ch", "Ô", "Š", "Ž" ),
        'sl' => array( "Č", "Š", "Ž" ),
        'smn' => array( "Á", "Č", "Đ", "Ŋ", "Š", "Ŧ", "Ž", "Æ", "Ø", "Å", "Ä", "Ö" ),
        'sq' => array( "Ç", "Dh", "Ë", "Gj", "Ll", "Nj", "Rr", "Sh", "Th", "Xh", "Zh" ),
        'sr' => array(),
        'tk' => array( "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ),
        'tl' => array( "Ñ", "Ng" ),
        'tr' => array( "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ),
        'tt' => array( "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ),
        'uz' => array( "Ch", "G'", "Ng", "O'", "Sh" ),
    );

    const RECORD_LENGTH = 14;

    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;
        $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 );
    }

    function getSortKey( $string ) {
        // intl extension produces non null-terminated
        // strings. Appending '' fixes it so that it doesn't generate
        // a warning on each access in debug php.
        wfSuppressWarnings();
        $key = $this->mainCollator->getSortKey( $string ) . '';
        wfRestoreWarnings();
        return $key;
    }

    function getPrimarySortKey( $string ) {
        wfSuppressWarnings();
        $key = $this->primaryCollator->getSortKey( $string ) . '';
        wfRestoreWarnings();
        return $key;
    }

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

        // Check for CJK
        $firstChar = mb_substr( $string, 0, 1, 'UTF-8' );
        if ( ord( $firstChar ) > 0x7f
            && self::isCjk( utf8ToCodepoint( $firstChar ) ) )
        {
            return $firstChar;
        }

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

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

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

    function getFirstLetterData() {
        if ( $this->firstLetterData !== null ) {
            return $this->firstLetterData;
        }

        $cache = wfGetCache( CACHE_ANYTHING );
        $cacheKey = wfMemcKey( 'first-letters', $this->locale );
        $cacheEntry = $cache->get( $cacheKey );

        if ( $cacheEntry && isset( $cacheEntry['version'] )
            && $cacheEntry['version'] == self::FIRST_LETTER_VERSION
        ) {
            $this->firstLetterData = $cacheEntry;
            return $this->firstLetterData;
        }

        // Generate data from serialized data file

        if ( isset( self::$tailoringFirstLetters[$this->locale] ) ) {
            $letters = wfGetPrecompiledData( "first-letters-root.ser" );
            // 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] );
            }
        } else {
            $letters = wfGetPrecompiledData( "first-letters-{$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 = array();
        foreach ( $letters as $letter ) {
            $key = $this->getPrimarySortKey( $letter );
            if ( isset( $letterMap[$key] ) ) {
                // Primary collision
                // Keep whichever one sorts first in the main collator
                if ( $this->mainCollator->compare( $letter, $letterMap[$key] ) < 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 = array();
        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." );
            unset( $letterMap[$badKey] );
            // This code assumes that unsetting does not change sort order.
        }
        $data = array(
            'chars' => array_values( $letterMap ),
            'keys' => array_keys( $letterMap ),
            'version' => self::FIRST_LETTER_VERSION,
        );

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

        // Save to cache
        $this->firstLetterData = $data;
        $cache->set( $cacheKey, $data, 86400 * 7 /* 1 week */ );
        return $data;
    }

    function getLetterByIndex( $index ) {
        if ( $this->firstLetterData === null ) {
            $this->getFirstLetterData();
        }
        return $this->firstLetterData['chars'][$index];
    }

    function getSortKeyByLetterIndex( $index ) {
        if ( $this->firstLetterData === null ) {
            $this->getFirstLetterData();
        }
        return $this->firstLetterData['keys'][$index];
    }

    function getFirstLetterCount() {
        if ( $this->firstLetterData === null ) {
            $this->getFirstLetterData();
        }
        return count( $this->firstLetterData['chars'] );
    }

    function findLowerBound( $valueCallback, $valueCount, $comparisonCallback, $target ) {
        if ( $valueCount === 0 ) {
            return false;
        }

        $min = 0;
        $max = $valueCount;
        do {
            $mid = $min + ( ( $max - $min ) >> 1 );
            $item = call_user_func( $valueCallback, $mid );
            $comparison = call_user_func( $comparisonCallback, $target, $item );
            if ( $comparison > 0 ) {
                $min = $mid;
            } elseif ( $comparison == 0 ) {
                $min = $mid;
                break;
            } else {
                $max = $mid;
            }
        } while ( $min < $max - 1 );

        if ( $min == 0 ) {
            $item = call_user_func( $valueCallback, $min );
            $comparison = call_user_func( $comparisonCallback, $target, $item );
            if ( $comparison < 0 ) {
                // Before the first item
                return false;
            }
        }
        return $min;
    }

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

    static function getICUVersion() {
        return defined( 'INTL_ICU_VERSION' ) ? INTL_ICU_VERSION : false;
    }

    static function getUnicodeVersionForICU() {
        $icuVersion = IcuCollation::getICUVersion();
        if ( !$icuVersion ) {
            return false;
        }

        $versionPrefix = substr( $icuVersion, 0, 3 );
        // Source: http://site.icu-project.org/download
        $map = array(
            '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',
        );

        if ( isset( $map[$versionPrefix] ) ) {
            return $map[$versionPrefix];
        } else {
            return false;
        }
    }
}