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<?php
/**
* Cross-Language Language name search
*
* Copyright (C) 2012 Alolita Sharma, Amir Aharoni, Arun Ganesh, Brandon Harris,
* Niklas Laxström, Pau Giner, Santhosh Thottingal, Siebrand Mazeland and other
* contributors. See CREDITS for a list.
*
* UniversalLanguageSelector is dual licensed GPLv2 or later and MIT. You don't
* have to do anything special to choose one license or the other and you don't
* have to notify anyone which license you are using. You are free to use
* UniversalLanguageSelector in commercial projects as long as the copyright
* header is left intact. See files GPL-LICENSE and MIT-LICENSE for details.
*
* @file
* @ingroup Extensions
* @license GPL-2.0-or-later
* @license MIT
*/
class LanguageNameSearch {
/**
* Find languages with fuzzy matching.
* The order of results is following:
* 1: exact language code match
* 2: exact language name match in any language
* 3: prefix language name match in any language
* 4: infix language name match in any language
*
* The returned language name for autocompletion is the first one that
* matches in this list:
* 1: exact match in [user, autonym, any other language]
* 2: prefix match in [user, autonum, any other language]
* 3: inline match in [user, autonym, any other language]
*
* @param string $searchKey
* @param int $typos
* @param string|null $userLanguage Language tag.
* @return array
*/
public static function search( $searchKey, $typos = 0, $userLanguage = null ) {
$results = [];
$searchKey = mb_strtolower( $searchKey );
// Always prefer exact language code match
if ( Language::isKnownLanguageTag( $searchKey ) ) {
$name = mb_strtolower( Language::fetchLanguageName( $searchKey, $userLanguage ) );
// Check if language code is a prefix of the name
if ( strpos( $name, $searchKey ) === 0 ) {
$results[$searchKey] = $name;
} else {
$results[$searchKey] = "$searchKey – $name";
}
}
$index = self::getIndex( $searchKey );
$bucketsForIndex = [];
if ( isset( LanguageNameSearchData::$buckets[$index] ) ) {
$bucketsForIndex = LanguageNameSearchData::$buckets[$index];
}
// types are 'prefix', 'infix' (in this order!)
foreach ( $bucketsForIndex as $bucketType => $bucket ) {
foreach ( $bucket as $name => $code ) {
// We can skip checking languages we already have in the list
if ( isset( $results[ $code ] ) ) {
continue;
}
// Apply fuzzy search
if ( !self::matchNames( $name, $searchKey, $typos ) ) {
continue;
}
// Once we find a match, figure out the best name to display to the user
// If $userLanguage is not provided (null), it is the same as autonym
$candidates = [
mb_strtolower( Language::fetchLanguageName( $code, $userLanguage ) ),
mb_strtolower( Language::fetchLanguageName( $code, null ) ),
$name
];
foreach ( $candidates as $candidate ) {
if ( $searchKey === $candidate ) {
$results[$code] = $candidate;
continue 2;
}
}
foreach ( $candidates as $candidate ) {
if ( self::matchNames( $candidate, $searchKey, $typos ) ) {
$results[$code] = $candidate;
continue 2;
}
}
}
}
return $results;
}
public static function matchNames( $name, $searchKey, $typos ) {
return strrpos( $name, $searchKey, -strlen( $name ) ) !== false
|| ( $typos > 0 && self::levenshteinDistance( $name, $searchKey ) <= $typos );
}
public static function getIndex( $name ) {
$codepoint = self::getCodepoint( $name );
if ( $codepoint < 4000 ) {
// For latin etc. we need smaller buckets for speed
return $codepoint;
} else {
// Try to group names of same script together
return $codepoint - ( $codepoint % 1000 );
}
}
/**
* Get the code point of first letter of string
*
* @param string $str
* @return int Code point of first letter of string
*/
public static function getCodepoint( $str ) {
$values = [];
$lookingFor = 1;
$strLen = strlen( $str );
$number = 0;
for ( $i = 0; $i < $strLen; $i++ ) {
$thisValue = ord( $str[$i] );
if ( $thisValue < 128 ) {
$number = $thisValue;
break;
} else {
// Codepoints larger than 127 are represented by multi-byte sequences
if ( $values === [] ) {
// 224 is the lowest non-overlong-encoded codepoint.
$lookingFor = ( $thisValue < 224 ) ? 2 : 3;
}
$values[] = $thisValue;
if ( count( $values ) === $lookingFor ) {
// Refer http://en.wikipedia.org/wiki/UTF-8#Description
if ( $lookingFor === 3 ) {
$number = ( $values[0] % 16 ) * 4096;
$number += ( $values[1] % 64 ) * 64;
$number += $values[2] % 64;
} else {
$number = ( $values[0] % 32 ) * 64;
$number += $values[1] % 64;
}
break;
}
}
}
return $number;
}
/**
* Calculate the Levenshtein distance between two strings
* @param string $str1
* @param string $str2
* @return int
*/
public static function levenshteinDistance( $str1, $str2 ) {
if ( $str1 === $str2 ) {
return 0;
}
$length1 = mb_strlen( $str1, 'UTF-8' );
$length2 = mb_strlen( $str2, 'UTF-8' );
if ( $length1 === 0 ) {
return $length2;
}
if ( $length1 < $length2 ) {
return self::levenshteinDistance( $str2, $str1 );
}
$prevRow = range( 0, $length2 );
for ( $i = 0; $i < $length1; $i++ ) {
$currentRow = [];
$currentRow[0] = $i + 1;
$c1 = mb_substr( $str1, $i, 1, 'UTF-8' );
for ( $j = 0; $j < $length2; $j++ ) {
$c2 = mb_substr( $str2, $j, 1, 'UTF-8' );
$insertions = $prevRow[$j + 1] + 1;
$deletions = $currentRow[$j] + 1;
$substitutions = $prevRow[$j] + ( ( $c1 !== $c2 ) ? 1 : 0 );
$currentRow[] = min( $insertions, $deletions, $substitutions );
}
$prevRow = $currentRow;
}
return $prevRow[$length2];
}
}
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