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<?php
/**
* Database row sorting.
*
* 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
* @author Tim Starling
*/
abstract class Collation {
private static $instance;
/**
* @since 1.16.3
* @return Collation
*/
public static function singleton() {
if ( !self::$instance ) {
global $wgCategoryCollation;
self::$instance = self::factory( $wgCategoryCollation );
}
return self::$instance;
}
/**
* @since 1.16.3
* @throws MWException
* @param string $collationName
* @return Collation
*/
public static function factory( $collationName ) {
switch ( $collationName ) {
case 'uppercase':
return new UppercaseCollation;
case 'identity':
return new IdentityCollation;
case 'uca-default':
return new IcuCollation( 'root' );
case 'xx-uca-ckb':
return new CollationCkb;
case 'xx-uca-et':
return new CollationEt;
default:
$match = [];
if ( preg_match( '/^uca-([a-z@=-]+)$/', $collationName, $match ) ) {
return new IcuCollation( $match[1] );
}
# Provide a mechanism for extensions to hook in.
$collationObject = null;
Hooks::run( 'Collation::factory', [ $collationName, &$collationObject ] );
if ( $collationObject instanceof Collation ) {
return $collationObject;
}
// If all else fails...
throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
}
}
/**
* Given a string, convert it to a (hopefully short) key that can be used
* for efficient sorting. A binary sort according to the sortkeys
* corresponds to a logical sort of the corresponding strings. Current
* code expects that a line feed character should sort before all others, but
* has no other particular expectations (and that one can be changed if
* necessary).
*
* @since 1.16.3
*
* @param string $string UTF-8 string
* @return string Binary sortkey
*/
abstract function getSortKey( $string );
/**
* Given a string, return the logical "first letter" to be used for
* grouping on category pages and so on. This has to be coordinated
* carefully with convertToSortkey(), or else the sorted list might jump
* back and forth between the same "initial letters" or other pathological
* behavior. For instance, if you just return the first character, but "a"
* sorts the same as "A" based on getSortKey(), then you might get a
* list like
*
* == A ==
* * [[Aardvark]]
*
* == a ==
* * [[antelope]]
*
* == A ==
* * [[Ape]]
*
* etc., assuming for the sake of argument that $wgCapitalLinks is false.
*
* @since 1.16.3
*
* @param string $string UTF-8 string
* @return string UTF-8 string corresponding to the first letter of input
*/
abstract function getFirstLetter( $string );
}
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