Expose $wgMaxArticleSize in siteinfo query api

[mediawiki.git] / includes / collation / IcuCollation.php

<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * @since 1.16.3
 */
class IcuCollation extends Collation {
        const FIRST_LETTER_VERSION = 2;

        /** @var Collator */
        private $primaryCollator;

        /** @var Collator */
        private $mainCollator;

        /** @var string */
        private $locale;

        /** @var Language */
        protected $digitTransformLanguage;

        /** @var array */
        private $firstLetterData;

        /**
         * Unified CJK blocks.
         *
         * The same definition of a CJK block must be used for both Collation and
         * generateCollationData.php. These blocks are omitted from the first
         * letter data, as an optimisation measure and because the default UCA table
         * is pretty useless for sorting Chinese text anyway. Japanese and Korean
         * blocks are not included here, because they are smaller and more useful.
         */
        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
        ];

        /**
         * Additional characters (or character groups) to be considered separate
         * letters for given languages, or to be removed from the list of such
         * letters (denoted by keys starting with '-').
         *
         * These are additions to (or subtractions from) the data stored in the
         * first-letters-root.ser file (which among others includes full basic latin,
         * cyrillic and greek alphabets).
         *
         * "Separate letter" is a letter that would have a separate heading/section
         * for it in a dictionary or a phone book in this language. This data isn't
         * used for sorting (the ICU library handles that), only for deciding which
         * characters (or character groups) to use as headings.
         *
         * Initially generated based on the primary level of Unicode collation
         * tailorings available at http://developer.mimer.com/charts/tailorings.htm ,
         * later modified.
         *
         * Empty arrays are intended; this signifies that the data for the language is
         * available and that there are, in fact, no additional letters to consider.
         */
        private static $tailoringFirstLetters = [
                // Verified by native speakers
                'be' => [ "Ё" ],
                'be-tarask' => [ "Ё" ],
                'cy' => [ "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ],
                'en' => [],
                'fa' => [ "آ", "ء", "ه" ],
                'fi' => [ "Å", "Ä", "Ö" ],
                'fr' => [],
                'hu' => [ "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ],
                'is' => [ "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ],
                'it' => [],
                'lv' => [ "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ],
                'pl' => [ "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ],
                'pt' => [],
                'ru' => [],
                'sv' => [ "Å", "Ä", "Ö" ],
                'sv@collation=standard' => [ "Å", "Ä", "Ö" ],
                'uk' => [ "Ґ", "Ь" ],
                'vi' => [ "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ],
                // Not verified, but likely correct
                'af' => [],
                'ast' => [ "Ch", "Ll", "Ñ" ],
                'az' => [ "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ],
                'bg' => [],
                'br' => [ "Ch", "C'h" ],
                'bs' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
                'ca' => [],
                'co' => [],
                'cs' => [ "Č", "Ch", "Ř", "Š", "Ž" ],
                'da' => [ "Æ", "Ø", "Å" ],
                'de' => [],
                'dsb' => [ "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ],
                'el' => [],
                'eo' => [ "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ],
                'es' => [ "Ñ" ],
                'et' => [ "Š", "Ž", "Õ", "Ä", "Ö", "Ü", "W" ], // added W for CollationEt (xx-uca-et)
                'eu' => [ "Ñ" ],
                'fo' => [ "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ],
                'fur' => [ "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ],
                'fy' => [],
                'ga' => [],
                'gd' => [],
                'gl' => [ "Ch", "Ll", "Ñ" ],
                'hr' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
                'hsb' => [ "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ],
                'kk' => [ "Ү", "І" ],
                'kl' => [ "Æ", "Ø", "Å" ],
                'ku' => [ "Ç", "Ê", "Î", "Ş", "Û" ],
                'ky' => [ "Ё" ],
                'la' => [],
                'lb' => [],
                'lt' => [ "Č", "Š", "Ž" ],
                'mk' => [],
                'mo' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
                'mt' => [ "Ċ", "Ġ", "Għ", "Ħ", "Ż" ],
                'nl' => [],
                'no' => [ "Æ", "Ø", "Å" ],
                'oc' => [],
                'rm' => [],
                'ro' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
                'rup' => [ "Ă", "Â", "Î", "Ľ", "Ń", "Ş", "Ţ" ],
                'sco' => [],
                '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' => [],
                'ta' => [
                        "\xE0\xAE\x82", "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"
                ],
                'tk' => [ "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ],
                'tl' => [ "Ñ", "Ng" ],
                'tr' => [ "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ],
                'tt' => [ "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ],
                'uz' => [ "Ch", "G'", "Ng", "O'", "Sh" ],
        ];

        /**
         * @since 1.16.3
         */
        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 );
        }

        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 '';
                }

                // Check for CJK
                $firstChar = mb_substr( $string, 0, 1, 'UTF-8' );
                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 '';
                }
                return $this->getLetterByIndex( $min );
        }

        /**
         * @since 1.16.3
         * @return array
         */
        public function getFirstLetterData() {
                if ( $this->firstLetterData === null ) {
                        $cache = ObjectCache::getLocalServerInstance( CACHE_ANYTHING );
                        $cacheKey = $cache->makeKey(
                                'first-letters',
                                $this->locale,
                                $this->digitTransformLanguage->getCode(),
                                self::getICUVersion(),
                                self::FIRST_LETTER_VERSION
                        );
                        $this->firstLetterData = $cache->getWithSetCallback( $cacheKey, $cache::TTL_WEEK, function () {
                                return $this->fetchFirstLetterData();
                        } );
                }
                return $this->firstLetterData;
        }

        /**
         * @return array
         * @throws MWException
         */
        private function fetchFirstLetterData() {
                // 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] );
                        }
                        // 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 );
                        }
                } 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 = [];
                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 = [];
                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;
        }

        /**
         * @since 1.16.3
         */
        public function getLetterByIndex( $index ) {
                return $this->getFirstLetterData()['chars'][$index];
        }

        /**
         * @since 1.16.3
         */
        public function getSortKeyByLetterIndex( $index ) {
                return $this->getFirstLetterData()['keys'][$index];
        }

        /**
         * @since 1.16.3
         */
        public function getFirstLetterCount() {
                return count( $this->getFirstLetterData()['chars'] );
        }

        /**
         * @since 1.16.3
         */
        public static function isCjk( $codepoint ) {
                foreach ( self::$cjkBlocks as $block ) {
                        if ( $codepoint >= $block[0] && $codepoint <= $block[1] ) {
                                return true;
                        }
                }
                return false;
        }

        /**
         * Return the version of ICU library used by PHP's intl extension,
         * or false when the extension is not installed of the version
         * can't be determined.
         *
         * The constant INTL_ICU_VERSION this function refers to isn't really
         * documented. It is available since PHP 5.3.7 (see PHP bug 54561).
         * This function will return false on older PHPs.
         *
         * @since 1.21
         * @return string|bool
         */
        static function getICUVersion() {
                return defined( 'INTL_ICU_VERSION' ) ? INTL_ICU_VERSION : false;
        }

        /**
         * Return the version of Unicode appropriate for the version of ICU library
         * currently in use, or false when it can't be determined.
         *
         * @since 1.21
         * @return string|bool
         */
        static function getUnicodeVersionForICU() {
                $icuVersion = IcuCollation::getICUVersion();
                if ( !$icuVersion ) {
                        return false;
                }

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