3 * Database row sorting.
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
25 * @author Tim Starling
27 abstract class Collation
{
28 private static $instance;
34 public static function singleton() {
35 if ( !self
::$instance ) {
36 global $wgCategoryCollation;
37 self
::$instance = self
::factory( $wgCategoryCollation );
39 return self
::$instance;
45 * @param string $collationName
48 public static function factory( $collationName ) {
51 switch ( $collationName ) {
53 return new UppercaseCollation
;
55 return new NumericUppercaseCollation( $wgContLang );
57 return new IdentityCollation
;
59 return new IcuCollation( 'root' );
60 case 'uca-default-u-kn':
61 return new IcuCollation( 'root-u-kn' );
63 return new CollationCkb
;
65 return new CollationEt
;
67 return new CollationFa
;
69 return new AbkhazUppercaseCollation
;
71 return new BashkirUppercaseCollation
;
73 return new NorthernSamiUppercaseCollation
;
76 if ( preg_match( '/^uca-([A-Za-z@=-]+)$/', $collationName, $match ) ) {
77 return new IcuCollation( $match[1] );
80 # Provide a mechanism for extensions to hook in.
81 $collationObject = null;
82 Hooks
::run( 'Collation::factory', [ $collationName, &$collationObject ] );
84 if ( $collationObject instanceof Collation
) {
85 return $collationObject;
88 // If all else fails...
89 throw new MWException( __METHOD__
. ": unknown collation type \"$collationName\"" );
94 * Given a string, convert it to a (hopefully short) key that can be used
95 * for efficient sorting. A binary sort according to the sortkeys
96 * corresponds to a logical sort of the corresponding strings. Current
97 * code expects that a line feed character should sort before all others, but
98 * has no other particular expectations (and that one can be changed if
103 * @param string $string UTF-8 string
104 * @return string Binary sortkey
106 abstract function getSortKey( $string );
109 * Given a string, return the logical "first letter" to be used for
110 * grouping on category pages and so on. This has to be coordinated
111 * carefully with convertToSortkey(), or else the sorted list might jump
112 * back and forth between the same "initial letters" or other pathological
113 * behavior. For instance, if you just return the first character, but "a"
114 * sorts the same as "A" based on getSortKey(), then you might get a
126 * etc., assuming for the sake of argument that $wgCapitalLinks is false.
130 * @param string $string UTF-8 string
131 * @return string UTF-8 string corresponding to the first letter of input
133 abstract function getFirstLetter( $string );